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Showing papers by "Yonsei University published in 1995"


Journal ArticleDOI
TL;DR: The Twenty Statements Test (TST) was administered in Seoul and New York, to 454 students from 2 cultures that emphasize collectivism and individualism, respectively as discussed by the authors. And responses, coded into 33 categories, were classified as either abstract or specific and as either autonomous or social.
Abstract: The Twenty Statements Test (TST) was administered in Seoul and New York, to 454 students from 2 cultures that emphasize collectivism and individualism, respectively. Responses, coded into 33 categories, were classified as either abstract or specific and as either autonomous or social. These 2 dichotomies were more independent in Seoul than in New York. The New York sample included Asian American whose spontaneous social identities differed. They either never listed ethnicity-nationality on the TST, or listed it once or twice. Unidentified Asian Americans' self-concepts resembled Euro-Americans' self-concepts, and twice identified Asian Americans' self-concepts resembled Koreans' self-concepts, in both abstractness-specificity and autonomy-sociality. Differential acculturation did not account for these results. Implications for social identity, self-categorization, and acculturation theory are discussed.

315 citations


Journal ArticleDOI
TL;DR: In this paper, a global information services function (ISF) quality framework is proposed to outline the importance of both behavioral and procedural dimensions in planning, implementing and evaluating global IS quality.
Abstract: Maintaining consistently high quality information services (IS) is a powerful means of increasing the overall efficiency and effectiveness of a global enterprise. This study introduces a global Information Services Function (ISF) Quality Framework that outlines the importance of both behavioral and procedural dimensions in planning, implementing and evaluating global IS quality. Based on this framework, the study investigates the cross-national psychometric properties of a behavioral measure of service quality in the IS context. Using a cross-national survey of IS customers from Korea, Hong Kong, the United States and the Netherlands, perceived ISF service quality was measured using a service quality measure (SERVQUAL) to determine cultural affects. Based on confirmatory factor analysis, support was found for four of the original five SERVQUAL quality dimensions in the U.S.A. and the Netherlands. However, the same four-dimensional measurement model did not fit the Hong Kong and Korean samples. Further factor analysis showed that the Hong Kong and Korean samples shared a somewhat similar factor structure that differs from the shared U.S.A. and Netherlands structure. These findings support previous research that has found an “Asian factor'’with differing definitions of IS Service quality. These findings suggest that the feasibility of standardized global ISF measurement depends heavily on the relative magnitude of cultural effects. Rather than merely applying the U.S.A. ISF/SERVQUAL measure, a localized version of the instrument may need to be developed that captures the unique nature of ISF service perceptions in internationally based subsidiaries or companies.

255 citations


Journal ArticleDOI
Kyu-Taik Sung1
TL;DR: Factor analysis and cross-validation of measures of affection, repayment, family harmony, respect, obligation, and sacrifice revealed two important factors--behaviorally oriented and emotionally oriented filial piety.
Abstract: Using survey data on 1,227 adult and pre-adult children in Korea, we identified some specific measures and dimensions of filial piety, a traditional East Asian value to respect and care for parents. Factor analysis and cross-validation of measures of affection, repayment, family harmony, respect, obligation, and sacrifice revealed two important factors--behaviorally oriented and emotionally oriented filial piety. These findings suggest that filial piety is two-dimensional, and that multiple indicators should be used to separately assess the behavioral and emotional components of modern-day filial piety.

226 citations


Journal ArticleDOI
Hyoung S. Baik1
TL;DR: The cephalometric radiographs of all subjects were analyzed before and after correction of anterior crossbite and the following results were obtained: after maxillary protraction, the maxilla and maxillary dentitions move forward and downward, and the mandible and mandibular dentitions moved backward and downward.

205 citations


Journal ArticleDOI
TL;DR: Dose dependent reduction of allodynia was observed after I.P. and ICV morphine, but not after IT morphine, IT or ICV c[D-pen2 D-pen5]enkephalin (DPDPE) (delta agonist), or IT orICV U50488H (kappa agonist).

185 citations


Journal Article
TL;DR: When evaluating the ear position with respect to the seventh cervical vertebra, the head was positioned more forward in the group with temporomandibular disorders than in the control group (P < .05).
Abstract: This study investigated the relationship between forward head posture and temporomandibular disorder symptoms. Thirty-three temporomandibular disorder patients with predominant complaints of masticatory muscle pain were compared with an age- and gender-matched control group. Head position was measured from photographs taken with a plumb line drawn from the ceiling to the lateral malleolus of the ankle and with a horizontal plane that was perpendicular to the plumb line and that passed through the spinous process of the seventh cervical vertebra. The distances from the plumb line to the ear, to the seventh vertebra, and to the shoulder were measured. Two angles were also measured: (1) ear-seventh cervical vertebra-horizontal plane and (2) eye-ear-seventh cervical vertebra. The only measurement that revealed a statistically significant difference was angle ear-seventh cervical vertebra-horizontal plane. This angle was smaller in the patients with temporomandibular disorders than in the control subjects. In other words, when evaluating the ear position with respect to the seventh cervical vertebra, the head was positioned more forward in the group with temporomandibular disorders than in the control group (P < .05).

151 citations


Journal ArticleDOI
TL;DR: Although epidermal grafting in combination with PUVA has some limitations, it is an easy, safe, inexpensive, and effective treatment for various types of stable refractory vitiligo.
Abstract: Background: Previous reports have shown the benefits of epidermal grafting for vitiligo. Objective: Our purpose was to evaluate the effectiveness and complications of epidermal grafting in combination with PUVA on stable vitiligo refractory to conventional treatments. Methods: In 100 patients with stable refractory vitiligo we performed epidermal grafting with suction blisters followed by PUVA treatment. The grafted sites were examined for repigmentation for up to 5 years. Results: Excellent repigmentation was observed at all grafted sites, especially on the face except for the lip and the alae nasae. PUVA treatment resulted in spreading of the pigmentation. Poor results were observed on the neck, axillae, and overlying bony prominences. Hyperpigmentation of the recipient and donor sites was frequently observed. Only six patients had recurrence and/or adjacent new lesions. Depigmentation developed at the donor site in only one patient with generalized vitiligo. Long-term observation in these patients indicates that repigmentation obtained by this method is permanent. Conclusion: Although epidermal grafting in combination with PUVA has some limitations, it is an easy, safe, inexpensive, and effective treatment for various types of stable refractory vitiligo.

143 citations


Journal ArticleDOI
TL;DR: The results of this study suggest that capsaicin and diallyl sulfide suppress VC- and NDMA-induced mutagenesis or tumorigenesis in part through inhibition of the cytochrome P-450 IIE1 isoform responsible for activation of these carcinogens.
Abstract: Capsaicin (trans-8-methyl-N-vanillyl-6-nonenamide) is a major pungent and irritating ingredient of hot chilli peppers, which are frequently consumed as spices. This dietary phytochemical has been found to interact with microsomal xenobiotic metabolizing enzymes in rodents. Capsaicin and its saturated analog dihydrocapsaicin (trans8-methyl-N-vanillyl-6-nonanamide) have been proposed to inactivate cytochrome P-450 IIE1 by irreversibly binding to the active sites of the enzyme. Besides cytochrome P-450 IIE1, other isoforms of the P-450 superfamily were also reported to be inhibited by capsaicin. The inhibition by capsaicin of microsomal monooxygenases involved in carcinogen activation implies its chemopreventive potential. As part of a program to investigate chemoprotective properties of capsaicin we initially determined the effect of capsaicin on vinyl carbamate (VC)- and N-nitrosodimethylamine (NDMA)-induced mutagenesis in Salmonella typhimurium TA100. Capsaicin (0.42 mM) attenuated the bacterial mutagenicity of VC and NDMA by 50% and 42% respectively. Diallyl sulfide, a thioether found in garlic with selective P-450 IIE1 inhibitory activity, also lessened the mutagenicity of the above carcinogens in a concentration-dependent manner. The suppression of VC- and NDMA-induced mutagenesis by capsaicin and diallyl sulfide correlated with their inhibition of P-450 IIE1-mediated p-nitrophenol hydroxylation and NDMA N-demethylation. Pretreatment of female ICR mice with a topical dose of capsaicin lowered the average number of VC-induced skin tumors by 62% at 22 weeks after promotion. A similar degree of protection was attained with oral administration of diallyl sulfide before carcinogen treatment. The results of this study suggest that capsaicin and diallyl sulfide suppress VC- and NDMA-induced mutagenesis or tumorigenesis in part through inhibition of the cytochrome P-450 IIE1 isoform responsible for activation of these carcinogens.

141 citations


Journal Article
TL;DR: The Lachman test was most sensitive in diagnosing chronic injuries of the anterior cruciate ligament and the pivot shift test was also sensitive but was influenced by many factors.
Abstract: In 147 patients with arthroscopically proved chronic injuries of the anterior cruciate ligament, the anterior drawer test, the Lachman test, and the pivot shift test were done before operation under general or spinal anesthesia. Results of the anterior drawer test were positive in 79.6% of the patients, in 98.6% patients having the Lachman test, and in 89.8% of patients having the pivot shift test. In 19 cases (12.9%), arthroscopic examination showed reattachment of the proximally torn end of the anterior cruciate ligament to the posterior cruciate ligament. In these cases, results of the anterior drawer test were positive in 13 patients (68.4%), in 17 (89.5%) patients having the Lachman test, and in 12 patients (63.2%) having the pivot shift test. In 15 cases with a false negative pivot shift test, arthroscopy showed blockage of anterior subluxation of the lateral tibial condyle by a partially functioning portion of the anterior cruciate ligament, which was reattached to the posterior cruciate ligament in 7 cases. In 2 cases with a false negative Lachman test, there was firm reattachment of the torn end of the anterior cruciate ligament to the proximal portion of the posterior cruciate ligament combined with a bucket handle tear of the medial meniscus. The Lachman test was most sensitive in diagnosing chronic injuries of the anterior cruciate ligament. The pivot shift test was also sensitive but was influenced by many factors.

129 citations


Journal Article
TL;DR: Possible breakthrough in treatment of erectile dysfunction could be arisen from active saponin extracted from red ginseng, bringing hopes to many sufferers of erectiles dysfunction.
Abstract: To investigate the efficacy in treating erectile dysfunction and to develop a natural drug without complications, the results of ginseng treatments are compared to placebo and other drug. A total of 90 patients with 30 patients in each group were closely followed. Changes in symptoms such as frequency of intercourse, premature ejaculation, and morning erections after treatment were not changed in all three groups (p > 0.05). However in the group receiving ginseng, changes in early detumescence and erectile parameters such as penile rigidity and girth, libido and patient satisfactions were significantly higher than that of other groups (p < 0.05). The overall therapeutic efficacies on erectile dysfunction were 60% for ginseng group and 30% for placebo and trazodone treated groups, statistically confirming the effect of ginseng (p < 0.05). No complete remission of erectile dysfunction was noted, but partial responses were reported. No cases of aggravation of symptoms were reported. AVS-penogram, which is a recording of penile hemodynamic changes during the natural erection after audiovisual erotic stimulation, is not changed after administration of ginseng. However if administered for a prolonged period of time, the cummulative effect on vascular flow might be seen. The administration of Korean red ginseng has shown to have superior effects compared to the placebo or trazodone. Definitely more researches are required to elucidate the mechanism of ginseng. The effects of saponin, extracted from ginseng, on smooth muscle of erectile tissues, can be evaluated using organ chamber or nitric oxide titration, thereby pinpointing the exact action mechanism of saponin. As more informations are available, possible breakthrough in treatment of erectile dysfunction could be arisen from active saponin extracted from red ginseng, bringing hopes to many sufferers of erectile dysfunction.

117 citations


Journal ArticleDOI
TL;DR: In this article, a constitutive model with a single yield surface was developed for the behavior of frictional materials such as clay, sand, concrete, and rock, based on concepts of elasticity and plasticity theories.

Journal ArticleDOI
TL;DR: Patients with limitation of motion of the elbow joint caused by the intraarticular pathologies were treated with the following arthroscopic procedures: removal of loose bodies, excision of osteophytes, anterior capsular release, abrasion arthroplasty, and partial excison of the radial head.
Abstract: Twenty-five patients with limitation of motion of the elbow joint caused by the intraarticular pathologies were treated with the following arthroscopic procedures: removal of loose bodies, excision of osteophytes, anterior capsular release, abrasion arthroplasty, and partial excision of the radial head. The extension of the elbow improved by 7 degrees, from a preoperative average of 21 degrees to a postoperative average of 14 degrees. The flexion of the elbow improved by 17 degrees, from a preoperative average of 113 degrees to a postoperative average of 130 degrees. The total range of motion improved by 24 degrees, from a preoperative average of 92 degrees to a postoperative average of 116 degrees. The average score of the Elbow Rating Scale of Morrey improved from a preoperative value of 2.8 to a postoperative value of 4.6. Twenty-three patients (92%) were satisfied with their results. Arthroscopy of the elbow is an effective diagnostic and therapeutic procedure for the limitation of motion caused by the intraarticular problems with minimal morbidity and rapid functional recovery.

Journal ArticleDOI
10 Sep 1995-Virology
TL;DR: Sequence analyses show that LRV2-1 differs significantly from members of the LRV1 genus which infect New World parasites, and support a view that transmission of LRV is strictly vertical and suggest thatLRV predate the divergence of Old and New World parasite.


Journal ArticleDOI
TL;DR: It is suggested that restriction fragment length polymorphism analysis of the VDR gene with a Bsm1 restriction enzyme in Koreans is not helpful for early detection of patients at risk of developing osteoporosis, even in patients with a high rate of bone turnover.
Abstract: To evaluate whether common allelic variants in the gene encoding the vitamin D receptor (VDR) were useful in predicting differences in bone mineral density (BMD) and bone turnover rate in Koreans, we analyzed the restriction pattern of the polymerase chain reaction product of the VDR gene with the Bsm1 enzyme and serum osteocalcin in patients with osteoporosis. The prevalence of the BB genotype in the controls was extremely low when compared with that in other reports: the BB, Bb, and bb genotypes accounted for 1.4%, 12.9%, and 85.7%, respectively. Only 2.8% of those patients with osteoporosis had the BB genotype. In contrast, 12.5% had the Bb genotype, and 84.7% had the bb genotype. The prevalence of the BB genotype in patients with severe osteoporosis was also extremely low: the BB, Bb, and bb genotypes accounted for 0%, 12.4%, and 87.6%, respectively. Compared with the mean serum osteocalcin level of the pre- and post-menopausal controls, the level in patients with severe osteoporosis was higher, and this was statistically significant. As expected, a negative correlation was observed between the serum osteocalcin levels and the age-matched Z scores for spinal BMD. However, no correlation was found in the femoral neck BMD. These results suggest that restriction fragment length polymorphism analysis of the VDR gene with a Bsm1 restriction enzyme in Koreans is not helpful for early detection of patients at risk of developing osteoporosis. This is true even in patients with a high rate of bone turnover. Our data suggest extreme ethnic differences in the pattern of prevalence of the VDR allele.

Journal ArticleDOI
Sung-Bae Cho1
TL;DR: The key point of this paper is to formalize modular neural networks as information sources, and show the feasibility of the fuzzy integral extended by OWA operators in the problem of combining neural outputs, especially in the case that the networks differ substantially from each other in accuracy.

Journal ArticleDOI
TL;DR: The stability of the two miniplate fixation technique was tested in a three-dimensional in vitro model and showed that in cases of angle fractures this fixation technique provides stable fixation under functional loading.
Abstract: In the case of mandibular angle fractures, a two miniplate fixation technique in which one plate is applied ventral to the oblique line and a second plate at the inferior border of the buccal cortex was used to stabilize the fracture. In this paper, the stability of the two miniplate fixation technique was tested in a three-dimensional in vitro model. The results of this study showed that in cases of angle fractures this fixation technique provides stable fixation under functional loading.

Journal ArticleDOI
TL;DR: Using the secondary school science achievement scores obtained by the International Association for the Evaluation of Educational Achievement, the authors provides more direct tests than others on the effect of human capital on economic growth, bearing important implications for theory and olicy.

Journal ArticleDOI
TL;DR: The results imply that the transcutaneous electrical stimulation used here produces an antinociceptive effect via a depressive action on the enhanced mechanical responsiveness of the spinal neurons in this rat model of peripheral neuropathy.

Journal ArticleDOI
01 Mar 1995-Geology
TL;DR: In this paper, the authors carried out a Sm-Nd isotopic reconnaissance study of South Korea and found that more than half of them exceed 2.5 Ga, indicating that South Korea has a long history of crustal evolution.
Abstract: We carried out a Sm-Nd isotopic reconnaissance study of South Korea. Eight river sediments gave crustal residence ages (T DM ) between 1.7 and 2.7 Ga, implying that, on average, the crust of South Korea was formed in Early to Middle Proterozoic time. Twenty-six Precambrian basement rocks yielded T DM between 1.4 and 3.8 Ga. More than half of them exceed 2.5 Ga, indicating that South Korea has a long history of crustal evolution. Four of the samples have T DM from 3.2 to 3.8 Ga suggesting the possibility that there may be ancient continental crust in Korea having ages comparable to those of the oldest cratons in the world. However, these samples also have preferentially higher Sm/Nd, so their old ages could be artifacts, thus requiring confirmation. The large variation in T DM of South Korea is reminiscent of that for the South China block. However, the existence of Early Archean ages better matches that of the North China block, because the basement of south China was thought to be mostly Proterozoic in age. The recent discovery of rare Archean basement rocks in the South China block may favor models that attempt to correlate South Korea with south China.

Journal ArticleDOI
TL;DR: It is concluded that the two-miniplate-fixation technique is indicated in cases of mandibular angle fracture to achieve stability of the fracture site and early mobility of the jaw.
Abstract: More stable fixation and greater resistance against infection are achieved in mandibular angle fractures if the two-miniplate-fixation technique is used One plate is applied at the superior border and a second plate is applied at the inferior border of the buccal cortex Strong support for this argument was demonstrated in these in vitro and pilot clinical studies It is concluded that the two-miniplate-fixation technique is indicated in cases of mandibular angle fracture to achieve stability of the fracture site and early mobility of the jaw

Journal ArticleDOI
Sangun Park1
TL;DR: The decomposition of the entropy of order statistics is considered, and some recurrence relations in the first r order statistics are derived, which yields a dual relation from a given relation in the entropyof order statistics.
Abstract: Calculation of the entropy of a set of consecutive order statistics is relatively more complicated than that of the entropy of the individual order statistic, which has been studied by Wong and Chan (1990). We provide some fundamental relations occurring in the entropy of consecutive-order statistics, which are very useful for computations. We first consider the decomposition of the entropy of order statistics, and derive some recurrence relations in the first r order statistics. We also establish a dual principle for the entropy of order statistics, which yields a dual relation from a given relation in the entropy of order statistics.

Journal ArticleDOI
TL;DR: The authors concluded that this anatomic variant of the medialMeniscus was not related to the patients' symptoms, but that reshaping the discoid lateral meniscus did relieve their symptoms.
Abstract: Discoid lateral meniscus in the knee joint is common. From July 1990 through September 1992, the authors performed arthroscopy on 534 symptomatic knee joints. Seventy-seven knees of 72 patients had discoid lateral meniscus. Of the 77 knees treated, 4 (5.5%) had discoid lateral meniscus associated with anomalous insertion of the anterior horn of the medial meniscus into the anterior cruciate ligament. The discoid lateral meniscus was reshaped in the 4 knees, and followup was done from 12 to 24 months (average, 20 months) after surgery. The results were satisfactory, except for 1 patient who damaged his knee in a traffic accident. The authors concluded that this anatomic variant of the medial meniscus was not related to the patients' symptoms, but that reshaping the discoid lateral meniscus did relieve their symptoms.

Journal ArticleDOI
01 Aug 1995-Spine
TL;DR: The mid-sagittal diameter of the lumbar spinal canal is narrowest in the Far Eastern Asian population, the radiologic criteria of spinal stenosis should be reconsidered for these people.
Abstract: STUDY DESIGN The anatomic dimensions of the vertebral body and spinal canal of the lumbar spine were analyzed in Koreans. OBJECTIVES To determine the normal dimension of the lumbar spinal canal in Koreans, to determine whether there are any racial differences in the morphometry of the lumbar spinal canal, and to provide criteria for diagnosing spinal stenosis in the Far Eastern Asian. SUMMARY OF BACKGROUND DATA Some radiologic and anatomic studies have been conducted regarding the size of the lumbar spinal canal of whites and blacks in western and African countries. METHODS One-thousand-eight-hundred measurements were performed on the transverse and sagittal diameters of vertebral bodies and spinal canals using complete sets of 90 lumbar vertebrae. RESULTS The mean mid-sagittal diameter of the lumbar spinal canal in the Korean population was less than that measured in white and African populations, but there was no significant differences between the Korean, white, and African populations regarding the transverse diameter of the lumbar spinal canal. CONCLUSION The mid-sagittal diameter of the lumbar spinal canal is narrowest in the Far Eastern Asian population; the radiologic criteria of spinal stenosis should be reconsidered for these people.

Journal ArticleDOI
TL;DR: In this paper, the authors document the change of the identities of Republicans and Democrats on trade policy and demonstrate in pooled cross-sectional analyses that presidents of both parties now exert a free-trade influence on House votes.
Abstract: We document the change of the identities of Republicans and Democrats on trade policy. This change involves a reversal of positions in the House of Representatives but a convergence on the presidential level. We also demonstrate in pooled cross-sectional analyses that presidents of both parties now exert a free-trade influence on House votes.

Journal ArticleDOI
TL;DR: A cross-sectional study was performed to find out if any specific correlations exist among height, leg length and arm span in growing Korean children, and it was found that the ratios were bigger in taller children in the same age group than the shorter ones in both sexes.
Abstract: A cross-sectional study was performed to find out if any specific correlations exist among height, leg length and arm span in growing Korean children. Height, leg length and arm span were measured ...

Journal ArticleDOI
TL;DR: In this paper, the authors consider quantum unbounded spin systems (lattice boson systems) in ν-dimensional lattice space Zν and prove that in a region of high temperatures the Gibbs state is unique, is translationally invariant, and has clustering properties.
Abstract: We consider quantum unbounded spin systems (lattice boson systems) in ν-dimensional lattice space Zν. Under appropriate conditions on the interactions we prove that in a region of high temperatures the Gibbs state is unique, is translationally invariant, and has clustering properties. The main methods we use are the Wiener integral representation, the cluster expansions for zero boundary conditions and for general Gibbs state, and explicitly β-dependent probability estimates. For one-dimensional systems we show the uniqueness of Gibbs states for any value of temperature by using the method of perturbed states. We also consider classical unbounded spin systems. We derive necessary estimates so that all of the results for the quantum systems hold for the classical systems by straightforward applications of the methods used in the quantum case.

Journal ArticleDOI
TL;DR: Mass shift of vector mesons in the nuclear medium is studied in two different approaches: the in-medium QCD sum-rule approach and the scattering-length approach, which is shown to be inapplicable to extract the hadron masses in the medium.
Abstract: Mass shift of vector mesons in the nuclear medium is studied in two different approaches: the in-medium QCD sum-rule approach and the scattering-length approach. The latter is shown to be inapplicable to extract the hadron masses in the medium. Further elaboration of the in-medium QCD sum rules is also discussed.

Journal ArticleDOI
TL;DR: It is demonstrated that anisakiasis is recognized as a public health problem in Korea and confirmed if larvae invading the gastric wall were observed by gastrofiberscopy.
Abstract: Human anisakiasis may occur after ingestion of raw marine fish infected with nematode larvae of Anisakidae. Anisakiasis caused by the migration of the larva into the wall of stomach, small intestine and other portion has been reported in Korea. This prospective study was made of all cases referred to parasitological laboratory in Cheju-do between June 1989 and June 1992. Gastric anisakiasis was confirmed if larvae invading the gastric wall were observed by gastrofiberscopy. One hundred and seven cases were diagnosed, most of which were in 30-49 years old. Most of the patients complained acute epigastric pain with history of eating raw marine fish. This symptom usually occurred about 12 hours to 1 day after ingestion of infected marine fish. Edema, erosion or ulcer of the mucosa and hemorrhage from the gastric wall were observed in the involved areas. Ninety larvae removed from the stomach were identified; the larva of Anisakis simplex was the most prevalent species, and the larva of Pseudoterranova decipiens was also detected. The important species of marine fish from which the patients became infected was demonstrated as yellow corvina, sea eel, ling, cuttle fish, yellowtail and others. Five species of marine fish as a possible source of infection were examined, and Anisakis simplex larvae and Pseudoterranova decipiens larvae were collected from the mackerel and rock cod. This study demonstrates that anisakiasis is recognized as a public health problem in Korea.

Journal ArticleDOI
TL;DR: In this article, the correlation between microstructural factors and mechanical properties of ultrafine steels processed by thermomechanical controlled treatments was clarified, and the formation of equiaxed grains in the steels might be explained by a possible strain-induced dynamic transformation mechanism associated with the austenite → ferrite transformation caused by heavy deformation in the Austenite range.
Abstract: The purpose of this study is to clarify the correlation between microstructural factors and mechanical properties of ultrafine steels processed by thermomechanical controlled treatments. Three steels deformed at high strain rates in a pilot plant rolling mill showed very fine ferritic microstructure, whose grains became more equiaxed and finer with increasing fraction of alloying elements, and had good tensile and fracture properties, although they contained only about 0.01 pct carbon. Especially in the Ni-added steel, tensile properties were greatly improved because of the high dislocation density and the fineness of the ferritic substructure, readily satisfying the requirements for commercial-grade high-strength, high-toughness steels. The formation of ultrafine equiaxed grains in the steels might be explained by a possible strain-induced dynamic transformation mechanism associated with the austenite → ferrite transformation caused by heavy deformation in the austenite range.