• Journal of the Korean Crystal Growth and Crystal Technology
• /
• v.9 no.4
• /
• pp.381-383
• /
• 1999

First topic of this paper aims to clarify how oxygen and heat transfer in silicon melt under cusp-shaped magnetic fields. We obtained asymmetric temperature distribution by using time dependent and three-dimensional calculation. Second topic is study on molecular dynamics simulation, which was carried out to estimate diffusion constants of oxygen in silicon melt.

• Proceedings of the Optical Society of Korea Conference
• /
• 2005.07a
• /
• pp.274-275
• /
• 2005

• Proceedings of the Zoological Society Korea Conference
• /
• 1996.10a
• /
• pp.92.1-92
• /
• 1996

No Abstract, See Full Text

• Proceedings of the Zoological Society Korea Conference
• /
• 2000.10a
• /
• pp.139.1-139
• /
• 2000

No Abstract, See Full Text

• Journal of the Korean Chemical Society
• /
• v.19 no.5
• /
• pp.386-393
• /
• 1975

Polystyrene and polystyrene blended with SBR were subjected to the mechanical degradation by roll mastication. The results obtained are as follows. 1. For the polystyrene which is blended with SBR, the overall shape of the molecular weight distribution curve moves from the higher molecular weight portion to the lower molecular weight portion, becomes narrower in breadth, and its peak becomes higher as the degradation proceeds. The final molecular weight distribution exhibits a relative uniformity. This is due to the fact that only the polymer molecules with the high molecular weight consisted in original polystyrene are degraded mechanically and produced the polymer molecules with the low molecular weight. 2. The scission number of polystyrene chains increases with mastication time, and the number of degraded polymer chains produced when the polymer is masticated for 100 minutes at 140, 150 and $160^{\circ}C$ are $2.36{\times}10^{20},\;1.76{\times}10^{20}\;and\;1.52{\times}10^{20}$, respectively. 3. The rate of the degradation of polystyrene decreases with the mastication temperature. The activation energy is found to have the negative value, -8.7 kcal/mole. Therefore it is indicated that the mechanical degradation is a chemical process of which the activation energy is supplied mechanically.

• Journal of Genetic Medicine
• /
• v.9 no.2
• /
• pp.73-77
• /
• 2012

Purpose: Fragile X carrier detection before or at early pregnancy through a wide screening program may not only confer a risk of having offspring with Fragile X syndrome (FXS), but may also confer a risk for Fragile X-associated primary ovarian insufficiency and Fragile X-associated tremor/ataxia syndrome. However, prior to the implementation of such a program, the carrier prevalence in a population and the availability of effective screening test should be evaluated. The aim of our study was to determine the prevalence of premutation carriers and to evaluate the feasibility of screening test. Materials and Methods: The blood samples were obtained from 8,641 pregnant women with no family history of mental retardation. We performed a three-primer CGG repeat primed (RP) PCR using the AmplideX$^{TM}$ FMR1 PCR kit (Asuragen, Inc. Austin, TX, USA). Samples showing full mutation alleles were reflexed to Southern blot analysis for methylation status and sizing. Results: Among the 8,641 women, we found 8 premutation carriers (1:1,090, 0.09%) and 46 women with an intermediate allele (1:190, 0.53%). No woman was found to carry the fully mutated allele. All the detected alleles were within the CGG repeat range of 8-117. Among the 8,641 samples, 29 and 30 CGG repeats represent 66.6% of all cases. The CGG RP PCR method provides robust detection of expanded alleles and resolves allele zygosity, thus minimizing the number of samples that require Southern blot analysis. Conclusion: This is the first study that has focused on the prevalence of FXS premutation carriers and FMR1 allele distribution in normal pregnant women. These data have important implications for population-based fragile X carrier screening in Korea.

• Journal of Photoscience
• /
• v.12 no.2
• /
• pp.87-93
• /
• 2005

A new assay technique to distinguish between pure compounds and the isomeric mixtures has been suggested using single molecule (SM) fluorescence detection technique. Since the number of emission spots in a fluorophorespread film prepared from a genuine dye solution was determined by experimental condition, the deviation of spot numbers from the expected values could be considered to be an indication of lower purity of the sample solution. The lower limit of sample concentration for this assay was determined to be $5{\times}10^{-10}$ M to show uniform number of expected spots within 10% uncertainties in our experimental condition. An individual fluorescence intensity distribution for a mixture of isomers having doubly different emissivities was simulated by adding distributions obtained from Cy3 and nile red (NR) independently. The result indicated that the mixture could be identified from the pure compounds through the difference in the number of Gaussian functions to fit the distribution. This new assay technique can be applied to the purity test for synthetic biofluorophores which are usually prepared in small quantities not enough for classical ensemble assays.

• The Korean Journal of Physiology and Pharmacology
• /
• v.3 no.4
• /
• pp.427-432
• /
• 1999

Although importance of intrapancreatic neurons containing gastrin-releasing peptide (GRP) in control of exocrine secretion has been raised, the nature of GRP in the pancreas is unclear. Thus, the present study was undertaken to see distribution, content and molecular heterogeneity of immunoreactive GRP in the rat pancreas. Content of immunoreactive GRP in the rat pancreas was $2.99\;{\pm}\;0.66$ ng/g wet tissues determined by radioimmunoassay. Immunoreactive GRP was most abundantly expressed in the duodenal part among 3 parts of the pancreas; duodenal, body and splenic part. Vagotomy failed to change the content of immunoreactive GRP in the pancreas. Three distinct forms of immunoreactive GRP, very identical to GRP-27, bombesin-24 and neuromedin C, were observed in the rat pancreas by using reversed phase $C_{18}$ HPLC and Sephadex G-50 superfine column chromatography. Cell bodies of neurons containing immunoreactive GRP were scattered in pancreatic connective tissues and their nerve fibers innervated pancreatic acini and large ducts as determined by immunohistochemistry. The present results suggest that three distinct forms of GRP exist in intrapancreatic GRPergic neurons, which exert a stimulatory role in pancreatic exocrine secretion in rats.

• Proceedings of the KIEE Conference
• /
• 2001.07c
• /
• pp.1337-1339
• /
• 2001

We have investigated the relation between the molecular weight distribution (MWD) of diffusible species and the recovery rate of hydrophobicity of room-temperature vulcanizing (RTV) silicone rubber (SIR) using solvent extraction at various temperatures. It was observed that the extract had a MWD ranging from a few hundreds g/mol to hundreds of thousands g/mol. By measuring the migration of siloxane to the extracted SIR surface through a thin carbon coating, the aspect of migration of diffusible species was observed as a real time plot, and the time constant of the migration was also calculated. According to the time dependence of IR-absorbance, the time constant was increased with the increase of MW of the extracts.

• 유체기계공업학회:학술대회논문집
• /
• 2006.08a
• /
• pp.383-386
• /
• 2006

In this study, we propose a new fast algorithm for calculating short range forces in molecular dynamics, This algorithm uses a new hierarchical tree data structure which has a high adaptiveness to the particle distribution. It can divide a parent cell into k daughter cells and the tree structure is independent of the coordinate system and particle distribution. We investigated the characteristics and the performance of the tree structure according to k. For parallel computation, we used orthogonal recursive bisection method for domain decomposition to distribute particles to each processor, and the numerical experiments were performed on a 32-node Linux cluster. We compared the performance of the oct-tree and developed new algorithm according to the particle distributions, problem sizes and the number of processors. The comparison was performed sing tree-independent method and the results are independent of computing platform, parallelization, or programming language. It was found that the new algorithm can reduce computing cost for a large problem which has a short search range compared to the computational domain. But there are only small differences in wall-clock time because the proposed algorithm requires much time to construct tree structure than the oct-tree and he performance gain is small compared to the time for single time step calculation.