Showing papers by "Seoul National University published in 1993"

Pulmonary tuberculosis: CT findings - Early active disease and sequential change with antituberculous therapy

Abstract: To evaluate findings of active pulmonary tuberculosis on computed tomographic (CT) scans and their sequential changes before and after antituberculous chemotherapy, 29 patients with newly diagnosed pulmonary tuberculosis and 12 patients with recent reactivation were studied prospectively. The diagnosis of active pulmonary tuberculosis was based on positive acid-fast bacilli in sputum (n = 29) and changes on serial radiographs obtained during treatment (n = 12). Twenty-six patients were followed up with CT during treatment for 1-20 months. Lungs from the cadavers of nine other patients, who died of pulmonary tuberculosis, were studied to provide a pathologic basis for diagnosis. At examination with CT, centrilobular lesions (nodules or branching linear structures 2-4 mm in diameter) were most commonly seen (n = 39 [95%]); in the 26 patients with follow-up, most of these lesions disappeared within 5 months after the start of treatment. In 11 of 12 patients with recent reactivation, CT clearly differentiated...

Maximum torque control of an induction machine in the field weakening region

Abstract: In this paper, a new approach to the induction machine control that ensures the production of maximum torque per ampere over the entire field weakening region is presented. Considering the limitations of voltage and current, the optimal current condition for yielding the maximum torque is obtained. Also, since the onset of the field weakening operation is automatically adjusted according to the flux level, the current limit and the voltage limit, smooth and precise transition can be obtained. The proposed scheme is verified through simulation and experiment with a 5-hp laboratory induction motor drive system. >

Preoperative staging of uterine cervical carcinoma: comparison of CT and MRI in 99 patients.

Abstract: OBJECTIVE The aim of this study was to compare CT and MRI at 0.5 T in the preoperative staging of uterine cervical cancer in a large series of patients. MATERIALS AND METHODS Ninety-nine patients with uterine cervical carcinoma underwent CT, MRI, and surgical exploration. RESULTS Both CT and MR findings were compared using surgical-pathologic findings as gold standards. Magnetic resonance imaging was superior to CT in tumor detection (sensitivity 75 vs. 51%, p < 0.005), in parametrial evaluation (accuracy 87 vs. 80%, p < 0.005), in overall tumor staging (accuracy 77 vs. 69%, p < 0.025), and in pelvic lymph node evaluation (accuracy 88 vs. 83%, p < 0.01). Magnetic resonance imaging had an accuracy of 76% in assessment of the thickness of cervical stromal invasion. CONCLUSION Magnetic resonance imaging was superior to CT in preoperative staging of uterine cervical carcinoma and MRI should be used instead of CT for preoperative staging of this disease.

Pharmacokinetics and pharmacodynamics of furosemide in protein-calorie malnutrition.

Abstract: The influence of dietary protein deficiency on pharmacokinetics and pharmacodynamics of furosemide was investigated after iv bolus (1 mg/100 g) and oral (2 mg/100 g) administration of furosemide to male Sprague-Dawley rats fed on a 23% (control) or a 5% (protein-calorie malnutrition: PCM) protein diet ad lib.for 4 weeks. After iv administration, the mean values of CL R , V ss, and the percentages of dose excreted in 8-hr urine as furosemide were increased 81, 31, and 61%, respectively, in PCM rats when compared with those in control rats, however, CL NR was 54% decreased in PCM rats. The decreased CLNR in PCM rats suggested the significantly decreased nonrenal metabolism of furosemide. The urine volume per g kidney after iv administration was not significantly different between the two groups of rats although the amount of furosemide excreted in 8-hr urine per g kidney increased significantly in PCM rats. The diuretic, natriuretic, kaluretic, and chloruretic efficiencies reduced significantly in PCM rats after iv administration. After oral administration, the extent of bioavailability increased considerably from 27.6% in control rats to 47.0% in PCM rats, probably as a result of decreased gastrointestinal and hepatic first-pass metabolism. This was supported by a tissue homogenate study; the amount of furosemide remaining per g tissue after 30-min incubation of 50 μg of furosemide with the 9000 × gsupernatant fraction of stomach (42.4 vs. 47.9 μg) and liver (41.4 vs. 45.9 μg) homogenates increased significantly in PCM rats. No significant differences in CLR and t1/2 were found between the control and the PCM rats after oral administration. The 24-hr urine volume and the amount of sodium excreted in 24-hr urine per g kidney increased significantly in PCM rats, and this might be due to a significantly increased amount of furosemide reaching the kidney excreted in urine per g kidney.

New control scheme for AC-DC-AC converter without DC link electrolytic capacitor

Abstract: A novel concept for a static three-phase to three-phase power converter for an AC motor drive with unity power factor and reduced harmonics on the utility line is presented. The power circuit consists of two back-to-back connected six-pulse bridges having only a 5-/spl mu/F ceramic capacitor in the DC link. By controlling the active power balance between two bridges, the DC link voltage can be maintained within a 20-V deviation from the nominal value with the small ceramic capacitor regardless of the load variation. >

Amniotic Fluid Interleukin-6 Determinations Are of Diagnostic and Prognostic Value in Preterm Labor

Abstract: PROBLEM: The purpose of this study was to determine if amniotic fluid concentrations of the interleukin-6 (IL-6) are of value in diagnosis of microbial invasion of the amniotic cavity and in the prediction of failure of tocolysis, preterm delivery and perinatal morbidity and mortality. METHOD: Amniotic fluid was obtained by transabdominal amniocentesis from 146 consecutive patients admitted with the diagnosis of preterm labor and intact membranes. Fluid was cultured for aerobic and anaerobic bacteria as well as for mycoplasmas. Amniotic fluid IL-6 levels were measured using a monoclonal antibody-based enzyme-linked immunosorbent assay with a sensitivity of 0.03 ng/ml. Logistic regression and Cox's proportional hazards model were used to examine the effect of several variables on dichotomous outcomes or interval to delivery. RESULTS: Patients with a positive amniotic fluid culture had a significantly higher amniotic fluid IL-6 concentrations than patients with a negative culture (median 91.2 ng/ml, range 0.9 to 437 ng/ml versus median 0.4 ng/ml, range <0.3 to 195 ng/ml, respectively; P<.0001). An amniotic fluid IL-6 concentration of greater than or equal to 11.3 ng/ml had a sensitivity of 93.3% (14 of 15) and a specificity of 91.6% (120 of 131). All patients with an amniotic fluid IL-6 concentration above 11.3 ng/ml and a negative amniotic fluid culture (N = 11) delivered preterm and all placenta available for examination (N = 7) had histologic evidence of chorioamnionitis. Amniotic fluid concentrations of IL-6 were an independent predictor of preterm delivery, amniocentesis-to-delivery interval and neonatal morbidity and mortality. Moreover, IL-6 concentrations added significant information to the prediction of these outcomes to that provided only by clinical information such as cervical dilatation, gestational age at admission or at delivery. CONCLUSION: IL-6 is a sensitive and rapid test for the detection of microbial invasion of the amniotic cavity and for identifying women at risk for spontaneous preterm delivery and neonates at risk for morbidity and mortality.

On the adaptive lattice notch filter for the detection of sinusoids

Abstract: A lattice notch filter for the detection and enchancement of sinusoids in noise is presented, and the convergence properties of the algorithm are investigated using ODE (ordinary differential equation) analysis. It is shown that the frequency estimate of the algorithm for a single sinusoid is unbiased, regardless of the pole-zero contraction factor and the noise variance. An expression for the MSE (mean square error) of the frequency estimate and the output SNR of the algorithm is derived. Simulation results are presented to verify the theoretical analysis. Based on cascading the proposed second-order adaptive notch filter, three different approaches for the detection of multiple sinusoids are presented. The first approach uses a linear cascade structure, and the second and third approaches use a triangular cascade structure. The performance of the algorithms for multiple sinusoids is investigated, and computer simulation results are presented and discussed. >

Pulmonary oil embolism after transcatheter oily chemoembolization of hepatocellular carcinoma.

Abstract: The medical records of 336 patients with hepatocellular carcinoma who underwent transcatheter oily chemoembolization (TOCE) performed via the hepatic artery were retrospectively reviewed to ascertain the occurrence of symptomatic pulmonary oil embolism. In 14 patients, more than 20 mL of iodized oil was administered. In six of these 14 patients, respiratory symptoms of cough, hemoptysis, and dyspnea developed 2-5 days after TOCE, and their chest radiographs showed diffuse bilateral pulmonary parenchymal infiltrate. Their arterial partial pressure of oxygen while they breathed room air ranged from 39 to 60 mm Hg during maximum hypoxemia. The symptoms, arterial hypoxemia, and chest radiographic abnormalities completely cleared 10-28 days after TOCE in the five patients who survived. One patient died 10 days after TOCE because of respiratory arrest with a progression of pulmonary infiltrate. Although histopathologic proof is lacking, it is concluded that massive pulmonary embolization of iodized oil was the primary cause of the clinical and radiographic manifestations in these six patients.

Multiposition alignment of strapdown inertial navigation system

Abstract: The authors demonstrate that the stationary alignment of strapdown inertial navigation system (SDINS) can be improved by employing the multiposition/technique. Using an observability analysis, it is shown that an optimal two-position alignment not only satisfies complete observability conditions but also minimizes alignment errors. This is done by analytic rank testing of the stripped observability matrix and numerical calculation of the error covariance. It is also shown that an optimal three-position alignment accelerates the convergence of the alignment error compared with two-position alignment. >

Natural occurrence of Fusarium mycotoxins (trichothecenes and zearalenone) in barley and corn in Korea.

Abstract: Barley is produced in four provinces, Chonbuk, Chonnam, Kyungbuk, and Kyungnam, and corn is mainly produced in the Kangwon province in Korea. The natural occurrence of Fusarium mycotoxins was surveyed in 39 barley and 46 corn samples from different areas. Five 8-ketotrichothecenes, namely deoxynivalenol (DON), nivalenol (NIV), 4-acetylnivalenol (4-ANIV), 3-acetyldeoxynivalenol (3-ADON), and 4,15-diacetylnivalenol (4,15-DANIV), and zearalenone (ZEA) were detected in barley. DON, NIV, and ZEA were the major contaminants in barley, with mean levels of 170, 1,011, and 287 ng/g, respectively. On the other hand, DON, 15-acetyldeoxynivalenol (15-ADON), NIV, 4-ANIV, 4,15-DANIV, and ZEA were detected in corn samples. DON and 15-ADON were the major contaminants in corn, with mean levels of 310 and 297 ng/g, respectively. The survey indicated that the natural occurrence of monoacetyl-DON and the ratios of NIV to DON in two cereals were different. In addition, this is the first report of the natural occurrence of 4,15-DANIV in cereals.

Stressed C60 layers on Au(001).

Abstract: The geometric and electronic structure of a ${\mathrm{C}}_{60}$ molecular layer on the Au(001) surfaces was studied by scanning tunneling microscopy and spectroscopy. The interaction between the substrate and overlayer is strong enough that the ${\mathrm{C}}_{60}$ monolayer is commensurate and uniaxially stressed along the 〈110〉 direction. As a result of stress the charge density around the ${\mathrm{C}}_{60}$ molecule appears to be deformed. Charge transfer was observed in ultraviolte photoemission spectroscopy and scanning tunneling spectroscopy, revealing the adsorption mechanism of the ${\mathrm{C}}_{60}$ molecule on this substrate.

An Alternative Approach to the Objective Measurement of Fabrics

Abstract: Objective measurements of fabric mechanical properties have great potential for quality control of clothing materials. However, access to the requisite instruments still remains a problem for many potential users due to their high cost. Therefore, a scheme for measuring all the relevant property parameters on an Instron is proposed in this article. Also, in view of the lengthy measurement process typically required by the Kawabata KES-FB system, this work provides a theoretical approach for selecting the pertinent parameters from those of the KES-FB system, so that measurement time and complexity of further data analysis can be reduced. As to the overall evaluation of fabric performance or utilization of acquired results, a graphical technique using circular diagrams is proposed to "fingerprint" or characterize fabrics. Data obtained on selected fabrics of different fiber types, weave construction, and fabric thickness are presented to illustrate this method and its applications.

Gelatinization and Retrogradation Characteristics of Hydroxypropylated and Cross-linked Rices

Abstract: Chemically modified rices were prepared by treating with propylene oxide and epichlorohydrin. Gelatinization and retrogradation characteristics of these modified rices were investigated by using DSC and amylograph. Hydroxypropylation of rice caused an extreme decrease in gelatinization temperature from 62 degrees C to 50 degrees C and reduced the retrogradation rate of cooked rice. In rice treated by both hydroxypropylation and cross-linking the retrogradation was reduced more than for hydroxypropylated rice.

Electron-spectroscopy study of rare-earth trihalides.

Abstract: We have studied the electronic structures of rare-earth trihalides ${\mathrm{LaF}}_{3}$, ${\mathrm{LaCl}}_{3}$, ${\mathrm{CeF}}_{3}$, ${\mathrm{CeCl}}_{3}$, and ${\mathrm{GdF}}_{3}$ by x-ray photoemission spectroscopy (XPS), bremsstrahlung isochromat spectroscopy (BIS), and electron-energy-loss spectroscopy (EELS). The double peak structures of the rare-earth 3d core-level XPS can be understood within the Anderson impurity model as being due to the charge transfer from the ligand 2p level to the rare-earth unfilled 4f level. The parameters obtained from fitting these core-level spectra using the Gunnarsson-Sch\"onhammer-model approach are consistent with the valence-band XPS and the conduction-band BIS spectra. In the higher binding-energy side (10--40 eV) of 3d XPS, several more satellites are observed. Through comparing with other core-level XPS and EELS, we find that they are mainly loss structures arising from the interband transition, the rare-earth 5p excitation, and the charge-transfer transition, but there are some contributions from the ``intrinsic'' plasmon excitations as well.

The Udo tuff cone, Cheju island, South Korea: transformation of pyroclastic fall into debris fall and grain flow on a steep volcanic cone slope

Abstract: The Udo tuff cone of Cheju Island, South Korea, is a middle Pleistocene basalt tuff cone that has formed by early Surtseyan-type eruptions and later drier hydroclastic eruptions. The tuff cone comprises steep (20–30°) and planar beds of lapillistone, lapilli tuff and tuff that can be grouped into seven sedimentary facies (A-G). Facies A and B comprise continuous to lenticular layers of grain-supported and openwork lapillistone that are inversely graded and coarsen downslope. They suggest emplacement by grain flows that are maintained by gravity-induced stress and grain collisions. Facies C includes poorly sorted, crudely bedded and locally inversely graded lapilli tuff, also suggestive of rapid deposition from highly concentrated grain flows. Facies D includes thinly stratified and mantle-bedded tuff that was probably deposited by fallout of wind-borne ash. Other facies include massive lapilli tuff (Facies E), chaotic lapilli tuff (Facies F) and cross-bedded tuffaceous sandstone (Facies G) that were deposited by resedimentation processes such as debris flow, slide/slump and stream flow, respectively. The grain flows that produced Facies A, B and C are interpreted to have originated from falling pyroclasts, which initially generated highly dispersed, saltating avalanches, in which momentum was transferred by the particles themselves. This transport mechanism is similar to that of debris fall. As the slope gradient was too low to maintain a highly dispersed flow, the debris fall decelerated and contracted due to a decrease in dispersive pressure. The mode of momentum transfer changed to one of collision because contraction of the debris fall resulted in an increase in particle concentration. This transport mechanism is similar to that of common grain flows. Grain segregation occurred in several ways. Initial segregation of ash from lapilli occurred due to their differing terminal fall velocities, and their contrasting degrees of sliding friction with the bed. Percolation of ash into interstices of lapilli during flow (kinematic sieving) augmented further segregation of ash from lapilli. The latter process, along with a dispersive pressure effect, gave rise to vertical inverse size grading. Downdip inverse grading was produced by particle overpassing.

Gymnophalloides seoi n. sp. (Digenea: Gymnophallidae), the first report of human infection by a gymnophallid.

Abstract: Gymnophalloides seoi n. sp. (Digenea: Gymnophallidae) is described from worms expelled from a naturally infected women in Korea. The patient, a 66-yr-old housewife, experienced severe epigastric discomfort, and fecal examination revealed numerous parasite eggs of 0.019-0.021 x 0.014-0.016 mm. After anthelmintic treatment and purgation, 952 digeneans consisting of 910 adult gymnophallids and 42 heterophyids (2 species) were recovered. The gymnophallid flukes closely resemble Gymnophalloides tokiensis Fujita, 1925 (known only as metacercariae from oysters), type and only previously known species of the genus, except for a difference in the position and orientation of the seminal vesicle. Without experimental proof of identity, the adult gymnophallids have been described as a new species, G. seoi, the only gymnophallid known to infect humans.

Antiinflammatory activity of naturally occurring flavone and flavonol glycosides

Abstract: Our previous report demonstrated that certain flavonoid aglycones such as apigenin (flavone), quercetin, morin (flavonols), and biochanin A (isoflavone) showedin vivo antiinflammatory activityvia topical and oral routes of administration. As a continual study, the various flavonoid glycosides have been evaluated in mouse ear edema assay using archidonic acid or crotonoil as a inflammagen. Flavonoids were orally administered (2 mg/mouse) and ear edema inhibition was measured. Significant antiinflammatory activities were found especially in flavone and flavonol glycosides (15–19% inhibition) although the flavonoid derivatives tested showed less antiinflammatory activity than hydrocortisone or indomethacin. Chalcone and flavanone derivatives were not significantly active. And in general, flavonol glycosides of kaempferol-type were found to have a higher oral antiinflammatory activity than that of flavonol glycosides of quercetin-type in mice.

Hepatic capillariasis: first case report in the Republic of Korea.

Abstract: We report a case of massive hepatic infection by Capillaria hepatica in a 14-month-old girl who presented with the symptom triad of persistent fever, hepatomegaly, and leukocytosis with eosinophilia. Twenty-five cases of human infection with this parasite, mostly in children, have been reported in the literature. This is the first case of hepatic capillariasis reported in the Republic of Korea. The diagnosis was made by needle biopsy of the liver. Scanning electron microscopic examination of the biopsy specimen was also performed. Thiabendazole therapy was initiated and the patient developed liver disease-related IgA nephropathy during the therapy. The literature dealing with proven cases of infection with C. hepatica is briefly reviewed.