Showing papers by "Kyungpook National University published in 1996"

Expression patterns of bone-related proteins during osteoblastic differentiation in MC3T3-E1 cells.

Abstract: Bone formation involves several tightly regulated gene expression patterns of bone-related proteins. To determine the expression patterns of bone-related proteins during the MC3T3-E1 osteoblast-like cell differentiation, we used Northern blotting, enzymatic assay, and histochemistry. We found that the expression patterns of bone-related proteins were regulated in a temporal manner during the successive developmental stages including proliferation (days 4-10), bone matrix formation/maturation (days 10-16), and mineralization stages (days 16-30). During the proliferation period (days 4-10), the expression of cell-cycle related genes such as histone H3 and H4, and ribosomal protein S6 was high. During the bone matrix formation/maturation period (days 10-16), type I collagen expression and biosynthesis, fibronectin, TGF-beta 1 and osteonectin expressions were high and maximal around day 16. During this maturation period, we found that the expression patterns of bone matrix proteins were two types: one is the expression pattern of type I collagen and TGF-beta 1, which was higher in the maturation period than that in both the proliferation and mineralization periods. The other is the expression pattern of fibronectin and osteonectin, which was higher in the maturation and mineralization periods than in the proliferation period. Alkaline phosphatase activity was high during the early matrix formation/maturation period (day 10) and was followed by a decrease to a level still significantly above the baseline level seen at day 4. During the mineralization period (days 16-30), the number of nodules and the expression of osteocalcin were high. Osteocalcin gene expression was increased up to 28 days. Our results show that the expression patterns of bone-related proteins are temporally regulated during the MC3T3-E1 cell differentiation and their regulations are unique compared with other systems. Thus, this cell line provides a useful in vitro system to study the developmental regulation of bone-related proteins in relation to the different stages during the osteoblast differentiation.

Strategy, Environment and Performance in Two Technological Contexts: Contingency Theory in Korea:

Abstract: This paper examines the range of application of strategic contingency theory. Its thesis is that as technologies and economies become more open to market forces, the tenets of contingency theory become increasingly relevant. The Korean economy seemed an ideal venue for testing this notion as it is very heterogeneous in the effectiveness of its technological regulation. Many Korean companies employing traditional technologies are able to benefit from government intervention, whereas most of those using emergent technolo gies — even in the same industry — are forced to compete internationally and are very much more subject to competitive market forces. We found that Korean companies using emergent technologies were more likely to do well if they heeded contingency prescriptions in making strategy: specifically, if they employed innovative and marketing differentiation strategies in uncertain environments and cost leadership strategies in stable contexts. On the other hand, companies that used traditional te...

Cosmological perturbations in generalized gravity theories.

Abstract: We analyze the cosmological perturbations valid in a broad class of generalized gravity theories in a unified manner. A complete set of perturbation equations is derived in gauge-ready forms. We present general asymptotic solutions for several different choices of the gauge conditions in unified forms. As in the case of Einstein's gravity, the uniform-curvature gauge is particularly simple for treating the scalar-type perturbations in generalized gravity theories involving the scalar field and the scalar curvature. Remarkably, considering the growing mode in the uniform-curvature gauge, the same solutions derived in Einstein's gravity remain valid in a broad class of generalized gravity theories.

A recognition of vehicle license plate using a genetic algorithm based segmentation

Abstract: Extracting a license plate is an important stage in automatic vehicle identification. It is very difficult because vehicle images are usually degraded and processing the images is computationally intensive. We propose a new method to extract the plate region using a distributed genetic algorithm. The algorithm offers robustness in dealing with deformation of vehicle images and inherent parallelism to improve the processing time. A test with seventy images shows an extraction rate of 92.8%, working well within real world situations. This results suggest that the proposed method is pertinent to be put into practical use.

Effects of heat treatment on Ta2O5 sensing membrane for low drift and high sensitivity pH-ISFET

Abstract: This paper presents a new approach for reducing the drift and improving the sensitivity of a pH-ISFET by varying the heat treatment condition of the Ta 2 O 5 sensing membrane. A Ta 2 O 5 pH-ISFET which was heat-treated at various temperatures, showed very different sensing characteristics such as sensitivity, long-term drift, etc. When heat-treated in O 2 ambient at 400°C for I h, Ta 2 O 5 pH-ISFET showed low drift, which is maybe related to a densification effect of the film in an amorphous state with a low leakage current. Furthermore, the Ta 2 O 5 pH-ISFET which was heat-treated in O 2 , showed good sensitivity, which is maybe associated with an increase of O-sites at the surface. The Ta 2 O 5 pH-ISFET fabricated by the above method showed good linearity, high sensitivity (58-59 mV) over a wide pH range (pH 2-12) and low long-term drift (0.03-0.05 pH/day).

Estimation of Median Income of Four-Person Families: A Bayesian Time Series Approach

Abstract: This article develops a general methodology for small domain estimation based on data from repeated surveys. The results are directly applied to the estimation of median income of four-person families for the 50 states and the District of Columbia. These estimates are needed by the U.S. Department of Health and Human Services (HHS) to formulate its energy assistance program for low income families. The U.S. Bureau of the Census, by an informal agreement, has provided such estimates to HHS through a linear regression methodology since the latter part of the 1970s. The current method is an empirical Bayes method (EB) that uses the Current Population Survey (CPS) estimates as well as the most recent decennial census estimates updated by the per capita income estimates of the Bureau of Economic Analysis. However, with the existing methodology, standard errors associated with these estimates are not easy to obtain. The EB estimates, when used naively, can lead to underestimation of standard errors. Mo...

Automatic Tuning of PID Controller Using Second-Order Plus Time Delay Model

Abstract: A new identification method using the second order plus time delay model for the automatic tuning of the PID controller and a simple and explicit tuning method are proposed. We present a relay feedback test combined with a P controller to identify the process using the second order plus time delay model. Thus, the difficulty to determine the initial proportional gain is overcome. Since the proposed identification method uses the second order plus time delay model to identify the prodess, it can incorporate more various processes such as underdamped and high order processes than the identification method using the first order plus time delay model. In addition, a simple and explicit tuning relation for the second order plus time delay model is proposed in this paper. This tuning relation shows almost the same performance as the optimal tuning parameters. The proposed method needs no numerical technique and shows good performances in both simulation and experimental study.

Microencapsulation of recombinant Saccharomyces cerevisiae cells with invertase activity in liquid-core alginate capsules.

Abstract: As a means of integrating cell growth and immobilization, recombinant Saccharomyces cerevisiae cells with invertase activity were immobilized in liquid-core alginate capsules and cultured to a high density. S. cerevisiae cells of SEY 2102 (MAT α ura3–52 leu2–3, 112 his4–519) harboring plasmid pRB58 with the SUC2 gene coding for invertase were grown to 83 g/L of liquid-core volume inside the capsule on a dry weight basis. The cloned invertase was expressed well in the immobilized cells with slightly higher activity than the free cells in a batch culture. Invertase in the immobilized cells showed slightly more improved thermal stability than in the free cells. Storage in a Na-acetate buffer at 4°C and 10°C for 1 month resulted in 7% and 8% loss in activity, respectively. The sucrose hydrolysis reaction was stably maintained for 25 repeated batches for 7 days at 30°C. Continuous hydrolysis of 0.3 M sucrose was carried out in a packed bed reactor with a conversion of more than 90% at a maximum productivity of 55.5 g glucose/L per hour for 7 days. In a continuous stirred tank reactor, the maximum productivity of 80.8 g glucose/L per hour was achieved at a conversion of 59.1% using 1.0 M sucrose solution, and 0.5 M sucrose solution was hydrolyzed for 1 week with a 95% conversion at a productivity of 48.8 g/L per hour. © 1996 John Wiley & Sons, Inc.

Low-power micro gas sensor

Abstract: The stable and low-power heating characteristics of a microheater are very important for the micro gas sensor. Membrane-type gas sensors have been fabricated by silicon IC technology. Steady-state thermal analysis by the finite-element method is performed to optimize the thermal properties of the gas sensor. From the analysis, the desirable size of the microheater for low power consumption is determined. The heating properties of fabricated poly-Si and Pt microheaters have been tested. The sensing characteristics of the packaged microsensor are also examined.

Mechanical and Dyeing Properties of Wool and Cotton Fabrics Treated with Low Temperature Plasma and Enzymes

Abstract: Cotton and wool fabrics were treated with low temperature oxygen plasma or en zymes or both and examined for their mechanical and dyeing properties. Plasma- treated cotton showed reduced strength, while the rate of weight loss in subsequent cellulase treatments decreased compared with untreated cotton. Equilibrium uptake of a direct dye remained unchanged regardless of plasma or cellulase treatment. The rate of dyeing increased, however, although the difference was slight, in the order of plasma treatment < untreated < cellulase treatment = plasma/cellulase treatment. Plasma pretreatment of wool caused an increase in strength and a higher rate of weight loss in the subsequent protease treatment. When wool was dyed with a leveling acid dye, equilibrium dye uptake did not change with plasma or protease pretreatment, but the dyeing rate increased with the plasma pretreatment With a milling acid dye, both increased greatly in the order of untreated < protease treatment < plasma treat ment < plasma/protease tr...

A novel flocculant biopolymer produced by Pestalotiopsis sp. KCTC 8637P

Abstract: A white rot fungus was isolated from rotted leaves and identified as Pestalotiopsis sp. KCTC 8637P. It produced a flocculant biopolymer. A flocculant was partially purified from the culture broth by series of precipitations with 95% ethanol and named as Pestan. The components of Pestan were consisted of glucose : glucosamine : glucuronic acid : rhamnose with a approximately molar ratio of 100:3.5:1.6:1.3.

A new pH-ISFET based dissolved oxygen sensor by employing electrolysis of oxygen

Abstract: A new dissolved oxygen sensor based on a pH-ISFET is discussed. A working electrode surrounding a pH-sensing gate of the pH-ISFET electrolyzes dissolved oxygen, resulting in a corresponding pH change near the pH-sensing gate. The pH-ISFET is expected to determine dissolved oxygen concentration by detecting this pH change. The results suggest that the proposed sensor operated by a combined mechanism of an amperometric sensor (Clark type sensor) and a potentiometric sensor (pH-ISFET) is feasible to determine the content of dissolved oxygen. The dependence of sensor output on several factors, such as buffering capacity, bulk pH and stirring of the solution, is investigated and a comparison between the Clark type sensor and proposed sensor is also discussed.

Vehicle Occupants’ Exposure to Aromatic Volatile Organic Compounds While Commuting on an Urban-Suburban Route in Korea

Abstract: This study identified in-auto and in-bus exposures to six selected aromatic volatile organic compounds (VOCs) for commutes on an urban-suburban route in Korea. A bus-service route was selected to include three segments of Taegu and one suburban segment (Hayang) to satisfy the criteria specified for this study. This study indicates that motor vehicle exhaust and evaporative emissions are major sources of both auto and bus occupants' exposures to aromatic VOCs in both Taegu and Hayang. A nonparametric statistical test (Wilcoxon test) showed that in-auto benzene levels were significantly different from in-bus benzene levels for both urban-segment and suburban-segment commutes. The test also showed that the benzene-level difference between urban-segment and suburban-segment commutes was significant for both autos and buses. An F-test showed the same statistical results for the comparison of the summed in-vehicle concentration of the six target VOCs (benzene, toluene, ethylbenzene, and o,m,p-xylenes) as those for the comparison of the in-vehicle benzene concentration. On the other hand, the in-vehicle benzene level only and the sum were not significantly different among the three urban-segment commutes and between the morning and evening commutes. The in-auto VOC concentrations were intermediate between the results for the Los Angeles and Boston. The in-bus VOC concentrations were about one-tenth of the Taipei, Taiwan results.

PCR and RFLP variation of conserved region of small subunit ribosomal DNA among Acanthamoeba isolates assigned to either A. castellanii or A. polyphaga

Abstract: Twelve isolates of Acanthamoeba spp. assigned to either A. castellanii or A. polyphaga, and type strains of A. culbertsoni, A. healyi, A. palestinensis, and A. astronyxis were examined by restriction fragment length polymorphism (RFLP) of a conserved region of small subunit ribosomal RNA gene (ssu rDNA) amplified by polymerase chain reaction (PCR). The PCR products of the isolates measured approximately 910-930 bp, except for that of A. astronyxis which was extraordinarily long, approximately 1,170 bp. Average of estimated sequence divergence of the amplified DNA among the isolates assigned to A. castellaii was 9.8% whereas that among the isolates assigned to A. polyphaga 9.6%. The maximum intraspecific sequence divergence among the isolates assigned to A. castellanii was observed between the Chang and Ma strains (17.3%) while that among the isolates assigned to A. polyphaga was observed between KA/S3 and KA/S7 strains (16.1%). The both maximum sequence divergences were much greater than the minimum interspecific sequence divergence between A. castellanii and A. polyphaga (2.6%) which appeared between the Castellani (or CCAP 1501/2 g) and KA/S3 strains. The PCR-RFLP patterns of A. culbertsoni, A. healyi, A. palestinensis, and A. astronyxis were quite diverse from one another and from those of isolates assigned to either A. castellanii or A. polyphaga. It is suggested that taxonomic validity of the isolates assigned to either A. castellanii or A. polyphaga should be reevaluated.

Electron microscopic observation of synaptic connections of jaw-muscle spindle and periodontal afferent terminals in the trigeminal motor and supratrigeminal nuclei in the cat.

Abstract: Previous studies indicate that the trigeminal motor nucleus (Vmo) and supratrigeminal nucleus (Vsup) receive direct projections from muscle spindle (MS) and periodontal ligament (PL) afferents. The aim of the present study is to examine the ultrastructural characteristics of the two kinds of afferent in both nuclei using the intracellular horseradish peroxidase (HRP) injection technique in the cat. Our observations are based on complete or near-complete reconstructions of 288 MS (six fibers) and 69 PL (eight fibers) afferent boutons in Vmo, and of 93 MS (four fibers) and 188 PL (four fibers) afferent boutons in Vsup. All the labeled boutons contained spherical synaptic vesicles and were presynaptic to neuronal elements, and some were postsynaptic to axon terminals containing pleomorphic, synaptic vesicles (P-endings). In Vmo neuropil, MS afferent boutons were distributed widely from soma to distal dendrites, but PL afferent boutons predominated on distal dendrites. Most MS afferent boutons (87%) formed synaptic specialization(s) with one postsynaptic target while some (13%) contacting two or three dendritic profiles; PL afferents had a higher number of boutons (43%) contacting two or more dendritic profiles. A small but significant number of MS afferent boutons (12%) received contacts from P-endings, but PL afferent boutons (36%) received three times as many contacts from P-endings as MS afferents. In Vsup neuropil, most MS (72%) and PL (87%) afferent boutons formed two contacts presynaptic to one dendrite and postsynaptic to one P-ending, and their participation in synaptic triads was much more frequent than in Vmo neuropil. The present study indicates that MS and PL afferent terminals have a distinct characteristic in synaptic arrangements in Vmo and Vsup and provides evidence that the synaptic organization of primary afferents differs between the neuropils containing motoneurons and their interneurons. © 1996 Wiley-Liss, Inc.

Synthesis and photocrosslinking of maleimide‐type polymers

Abstract: Self-sensitizable photocrosslinking maleimide-type polymers were synthesized by using (N-cinnamoyloxymethyl)maleimide (1) as a maleimide having a photodimerizable group, nitrophenyl acrylate as a sensitizer monomer, and styrene or methyl acrylate. The fluorescence spectra of these polymers exhibit an excimer band around 455 nm. The excimer intensity of the polymers decreased mainly during the early irradiation time. This decreasing tendency was similar to the increasing tendency of the insoluble fractions of the polymers with irradiation time. These results suggest that the photocrosslinking reaction of the polymers occurs via an excimer formation of the cinnamoyl groups and can be traced by fluorescence spectroscopy.

Wear and Wear Transition in Silicon Carbide Ceramics during Sliding

Abstract: Wear and wear transition in silicon carbide ceramics during sliding have been investigated. Three different microstructures, i.e., solid-state-sintered silicon carbide, liquid-phase-sintered silicon carbide, and a liquid-phase-sintered SiC-TiB{sub 2} composite, were produced by hot pressing. Wear data and examinations of worn surfaces showed that the wear behavior of these silicon carbide ceramics was significantly different. In the solid-state-sintered silicon carbide, the wear occurred by a grooving process. In the liquid-phase-sintered silicon carbide and composite, on the other hand, an abrupt transition in the wear mechanism from an initial grooving process to a grain pullout process occurred during the test. The transition occurred significantly earlier in the composite than in the carbide. The different wear behavior in these silicon carbide ceramics is discussed in relation to the grain or interphase boundary strength.

Substrate temperature dependence of ZnO films prepared by ultrasonic spray pyrolysis

Abstract: Strongly c-axis oriented zinc oxide (ZnO) films were deposited on silicon wafers coated with SiO2 or 7059 corning glass substrates from a solution containing zinc acetate. The films were deposited in a hot wall reactor by the pyrolysis of an aerosol produced by an ultrasonic generator. The crystallinity, surface morphology and composition of the films were studied using X-ray diffraction analysis (XRD), scanning electron microscopy (SEM) and Rutherford back-scattering spectrometry (RBS), respectively. The influences of the concentration of zinc acetate in the solution and the substrate temperature on the crystallinity of the films were studied. The films grown at a substrate temperature of 350–450° C from a 0.03 M/ l solution exhibited strong (002) orientation with a very smooth surface. The resistivity of the films was around 10 Ω cm. Oxidation resulted in a 10,000-fold increase in the resistivity.

Removal of Direct Red from Aqueous Solution by Foam Separation Techniques of Ion and Adsorbing Colloid Flotation

Abstract: Experimental investigations on the removal of Direct Red from an aqueous solution were carried out through two foam separation techniques: ion flotation and adsorbing colloid flotation with Fe(III). The residual concentration of Direct Red can be lowered to below 0.5 ppm in 3 minutes by ion flotation and below 0.1 ppm in 2 minutes by adsorbing colloid flotation. The optimum pH for the removal of Direct Red was found to be 4 for ion flotation and 3–5 for adsorbing colloid flotation. The effects of surfactant, foreign ions, and Al(III) addition on the removal of Direct Red are discussed.