• Transactions of the Korean Society of Mechanical Engineers
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• v.18 no.11
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• pp.2999-3007
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• 1994

The unsteady numerical simulations have been presented for the laminar natural convection in a partially open compartment. Computations were performed within the domain of the compartment in order to show the thermal radiation and the partially opening effects on the flow fields and heat transfer characteristics. The results were shown for different Planck numbers(0.05~5) and opening ratios(0.25~0.75) being fixed with Ra=$10^5$ and Pr=0.71. Considering the flow which is buoyancy driven from the heated wall, and the buoyancy is not much affected by the further outside region from the opening, the numerical computations have been performed without an outer region by the particular boundary treatments on the flow velocity and temperature at the different partial openings. The confined numerical domain reduced the CPU time and the memory of computer. P-1 approximation of radiative transfer equation was employed with Marshak type boundary conditions along with the pseudo-black body approximation at the partial openings. The numerical results clearly show that the natural convective flow and heat transfer are much affected by increase of thermal radiation particularly from the initial state. When thermal radiation is not much affecting the flow ($PL{\le}1$), it was found that thermal radiation effects are almost negligible.

• Korean Journal of Pharmacognosy
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• v.48 no.3
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• pp.213-218
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• 2017

In order to search for anticancer agent as therapy of oral squamous cell carcinoma (OSCC) and malignant pleural mesothelioma (MPM) from Korean traditional prescriptions, we selected 58 traditional prescriptions based on a review of the Korean traditional medicine books. Among the selected traditional prescriptions, only water extracts of paedoksan (敗毒散) showed relatively good cytotoxicity at the concentration of $50{\mu}g/ml$. Additionally, we evaluated cytotoxicity for various paedoksans and each herbal ingredient in paedoksans. The root of Anthriscus sylvestris exhibited more cytotoxic effect than any other ingredients in paedoksans. Bioactivity-guided fractionation of the MC layer of Anthriscus sylvestris led to the isolation of deoxypodophyllotoxin (DPT). DPT exhibited dose-dependently significant cytotoxicity against OSCC and MPM cell with nM range. Therefore, DPT from A. sylvestris might be a potential candidate as an effective anticancer therapeutic agent for OSCC and MPM.

• Journal of Life Science
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• v.9 no.1
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• pp.54-57
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• 1999

We have got several clones from Serratia marcescens which stimulated the cells to use maltose as a carbon source in E. coli TP2139 (${\Delta}$lac, ${\Delta}$crp). One of the cloned genes, pCKB13, was further analyzed. In order to find whether the increased expression of the gene under the direction of maltose metabolism, we constructed several recombinant subclones. We have confirmed that the clone, pCKB13 codes Coenzyme A transferase gene by partial nucleotide sequencing in the terminal region. The enzyme activity of Coenzyme A transferase increased after introduction of the multicopy of the cloned gene in E. coli. The recombinant proteins expressed by multicopy and induction with IPTG, two polypeptide of 26-and 28-kDa, were confirmed by SDS-PAGE. Southern hybridization analysis confirmed that the cloned DNA fragment was originated from S. marcescens chromosomal DNA.

• Environmental Analysis Health and Toxicology
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• v.15 no.4
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• pp.147-155
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• 2000

In order to evaluate anti -oxidant activities and protective effect against oxidatve damage, DPPH radical scavenging activity and lipid peroxidation inhibitory activity were measured among methanol extracts prepared from natural medicinal plants. Fourteen natural medicinal plants which were reported to have anti -oxidative or anti-inflammatory effects were selected based on our previous report. In addition to the total methanol extracts, n-hexane, dichloromethane, ethylacetate, n-butanol and water fractions were prepared from each total extract. DPPH radical scavenging assay was performed against 14 total extracts and all samples showed dose-dependent activities in various extent. Among those, 6 samples, methanol extracts of Euryale ferox, paeonia suffruticosa, Areca catechu var. dulcissima, Cinnamomun cassia, Alpinia katsumadai and Betula platyphlla var. japonica showed IC$\sub$50/ value lower than 6.0 $\mu\textrm{g}$/ml. The highest DPPH radical scavenging activity was found in ethylacetate fraction of paeonia suffruticosa with IC$\sub$50/ value of 1.1 $\mu\textrm{g}$/ml. Analysis of lipid peroxidation inhibitory activity on hydrogen peroxide-induced oxidative damage in Chinese hamster lung fibroblast (V79-4) cells revealed that the highest inhibitory effect was observed in methanol extract of Betula platyhpylla var. japonica. Lipid peroxidation inhibitory activity was observed as a dose-dependent manner in all samples used in this study. Among fraction samples, ethylacetate fraction of Alpinia katsumadai had the strongest inhibitory activity with IC$\sub$50/ value of 0.9 $\mu\textrm{g}$/ml.

• Journal of Environmental Impact Assessment
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• v.16 no.1
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• pp.89-98
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• 2007

In order to conduct the environmental assessment of long range transboundary air pollutants over East Asia, the moving pathways of air pollutants are of great importance, which are depending upon the meteorological weather patterns. Therefore regional scale modeling study requires the identified geopotential height distribution patterns to deal with behaviors of long range transport air pollutants for the effective long term atmospheric environmental assessment. In this study the synoptic meteorological classification using cluster analysis technique over Northeast Asia, and its previous applications of the regional scale air pollutant modeling studies were reviewed and summarized in detail. Other synoptic meteorological characteristics over Korean peninsula are also discussed.

• Journal of the Korean Society of Safety
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• v.17 no.2
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• pp.8-15
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• 2002

In order to investigate the vibration characteristics of fluid-structure interaction problem, we modeled two identical rectangular plates coupled with fluid. A commercial computer code, ANSYS was used to perform finite element analysis and FEM solutions were compared with the experimental results to verify the finite element model. As a result, comparison of FEM and experiment showed good agreement, and the transverse vibration modes, in-phase and out-of-Phase, were observed alternately in the fluid-coupled system. The effect of fluid gap size on the fluid-coupled natural frequency were investigated. It was shown that the mode numbers increased, the normalized natural frequencies monotonically increased. And it was also found that an increase of the fluid gap reduced the coupled natural frequencies for the in-phase modes but increased the coupled natural frequencies for the out-of phase modes, and eventually converged to the results of an infinite fluid gap.

• Clinical and Experimental Reproductive Medicine
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• v.16 no.1
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• pp.35-40
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• 1989

In order to study the follicular atretic mechanism in mammalian ovary, the relationship between pyknotic index (PI) of granulosa cells and the steroid concentrations in the follicular fluid of atretic follicle was investigated. Follicles were isolated from porcine ovary according to their sizes and the reproductive phases. Steroid concentrations were quantified by high-performance liquid chromatography. As PI increased, the concentration of progesterone was significantly increased(p<0.05), whereas testosterone and estradiol showed no significant changes in their concentration. As follicular size was increased, PI of follicular GC in the luteal phase was increased significantly(p<0.05) and the molar ratio of progesterone to testosterone was increased in the follicles of follicular phase. It can be concluded that progesterone accumulated in the follicular fluid as atresia of the follicles was progressed, and that PI of granulosa cells could be used as one of convenient and pratical criteria for the identification of follicular atresia.

• Clinical and Experimental Reproductive Medicine
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• v.18 no.2
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• pp.123-131
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• 1991

In order to study the growth and maturation of ovarian follicle, the localization and activity of alkaline phosphatase(ALPase) and adenosine triphosphatase(ATPase) of the granulosa cells and theca layer were examined according to the follicle size, the follicle state and the ovarian cyclic phase in pig. Theca interna of the small follicles was more heavyly localized with reaction product by the activites of ALPase and ATPase than that of the large follicles. It is assumed that, as the follicles proceed to growth and maturation, antrum formation is the result of the follicular fluid accumulation by means of active transport by the activities of ALPase and ATPase in theca interna. The activities of ALPase and ATPase in atretic follicles were higher than those of normal follicles. These results imply that the mechanisms of follicle maturation and atresia are different according to the phase of ovarian cycle.

• International Journal of High-Rise Buildings
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• v.3 no.1
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• pp.49-64
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• 2014

Natural vibration period is an important parameter for high-rise building, Based on 414 high-rise buildings completed or passed over-limit approval in China, the distribution law of natural vibration periods is analyzied. In order to satisfy the design requirements, such as global stability, story drift limit and minimum shear-gravity ratio, the reference ranges of fundamental periods $T_1$ are $0.3{\sqrt{H}}{\sim}0.4{\sqrt{H}}$ when the structural heights $H{\geq}250m$, when 150 m ${\leq}$ H < 250m, $T_1=0.25{\sqrt{H}}{\sim}0.4{\sqrt{H}}$, when 100 m ${\leq}$ H < 150 m, $T_1=0.2{\sqrt{H}}{\sim}0.35{\sqrt{H}}$, when 50 m $ {\leq}$ H < 100m, $T_1=0.15{\sqrt{H}}{\sim}0.3{\sqrt{H}}$. These can provide reference data for controlling mass and rigidity of high-rise buildings.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.18 no.6
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• pp.674-680
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• 2008

A new meshless method for obtaining natural frequencies of arbitrarily shaped plates with the free boundary condition is introduced in the paper. In order to improve the characteristics of convergence and accuracy of the method, a special local polar coordinates system is devised and located for each of nodes distributed along the boundary of the plate of interest. In addition, a new way of decreasing the size of the system matrix that gives natural frequencies of the plate is employed to reduce the amount of numerical calculations, which is needed for computing the determinant of the system matrix. Finally the excellence of the characteristics of convergence and accuracy of the method is shown in several case studies, which indicate that natural frequencies by the proposed method are very accurate and converged swiftly to exact values as the number of boundary nodes increases.