• Journal of Korean Biological Nursing Science
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• 제7권1호
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• pp.47-56
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• 2005

nm23-H1 gene expression has been inversely correlated with tumor metastatic potential in certain tumors including melanomas, breast carcinomas, and hepatocellular carcinomas. However, its role with respect to the invasive behavior of central nervous system tumors has scarcely been addressed Because cell motility and invasion plays an essential role in metastatic dissemination, we have studied whether motile human glioma cell(U87MG) transfected with nm23-H1 complementary DNA have any alterations in their ability to migrate and invade. There was no significant changes in the shape and size of the cells following nm23-H1 transfection. The role of nm23-H1 in glioma migration and invasion have been evaluated by in vitro simple scratch technique and brain slice invasion model Basal migration ability of nm23-H1 transfectants cell(U87MG-pEGFP-nm23) were lesser than U87MG. Accordingly, U87MG-pEGFP-nm23 didn't migrate away apparently from the tumors implanted site comparing U87MG in brain slice invasion model. These results suggest that nm23-H1 may play an important role in suppressing the human glioma migration and invasion.

• 산업공학
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• 제12권1호
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• pp.10-18
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• 1999

Job shop manufacturing environments are using the concept of cellular manufacturing systems(CMS) which has several advantages in reducing production lead times, setup times, work-in-process, etc. Utilizing the similarities between cell-machine, part-machine, and the shape/size of parts, CMS can group machines and parts resulting in improved efficiency of this system. However, when grouping machines and parts in machine cells, there inevitably occurs exceptional elements(EEs), which can not operate in the same machine cell. Minimizing these EEs in CMS is a critical point that improving production efficiency. Constraints in machine duplication cost, machining process technology, machining capability, and factory space limitations are main problems that prevent achiving the goal of maintaining an ideal CMS environment. This paper presents an algorithm that minimizes EEs under the constraints of machine duplication cost and factory space limitation. Developing exceptional operation similarity(EOS) by cell-machine incidence matrix and part-machine incidence matrix, it brings the machine cells that operate the parts or not. A mathematical model to minimize machine duplication is developed by EOS, followed by a heuristic algorithm in order to reflect dynamic situation resulting from minimizing exceptional elements process and the mathematical model. A numerical example is provided to illustrate the algorithm.

• 한국표면공학회지
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• 제28권3호
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• pp.164-173
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• 1995

Based on the potential-theory model for secondary current distribution, we could predict the thickness distributions of electroplating on patterned substrates with the different size of the auxiliary electrode. The substrates contain lithographic patterns at each sample geometry. Each sample geometry had different current distribution at the same condition except the size of the auxiliary electrodes. The size effect of the auxiliary electrode on thickness distribution of electrodeposition on patterned electrode was investigated in a series of experiments. Copper was galvanostatically deposited from an acid-sulfate solution in a reciprocating paddle cell. The thickness distributions of the workpiece scale measured by profilometry across the specimen were in good agreement with the current distribution predicted by boundary element method.

• 신재생에너지
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• 제19권3호
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• pp.1-12
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• 2023

This study aims to evaluate the optimal size of the hydrogen facility to be installed in a zero-energy district in terms of load matching and facility efficiency. A mismatch between energy generation and consumption is a common occurrence in zero-energy districts. This mismatch adversely effects the energy grid. However, using an energy carrier such as hydrogen can solve this problem. To determine the optimal size of hydrogen fuel cells to be used on-site, simulation of hydrogen installation is required at both district-and building- levels. Each case had four operating schedules. Therefore, we evaluated eight scenarios in terms of load matching, heat loss, and facility operational efficiency. The results indicate that district-level installation of hydrogen facilities enables more efficient energy use. Additionally, based on the proposed model, we can calculate the optimal size of the hydrogen facility.

• Wind and Structures
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• 제15권4호
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• pp.313-329
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• 2012

There have existed for a number of years good practice guidelines for the use of Computational Fluid Dynamics (CFD) in the field of wind engineering. As part of those guidelines, details are given for the size of flow domain that should be used around a building of height, H. For low-rise buildings, the domain sizes produced by following the guidelines are reasonable and produce results that are largely free from blockage effects. However, when high-rise or tall buildings are considered, the domain size based solely on the building height produces very large domains. A large domain, in most cases, leads to a large cell count, with many of the cells in the grid being used up in regions far from the building/wake region. This paper challenges this domain size guidance by looking at the effects of changing the domain size around a tall building. The RNG ${\kappa}-{\varepsilon}$ turbulence model is used in a series of steady-state solutions where the only parameter varied is the domain size, with the mesh resolution in the building/wake region left unchanged. Comparisons between the velocity fields in the near-field of the building and pressure coefficients on the building are used to inform the assessment. The findings of the work for this case suggest that a domain of approximately 10% the volume of that suggested by the existing guidelines could be used with a loss in accuracy of less than 10%.

• Maxillofacial Plastic and Reconstructive Surgery
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• 제19권3호
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• pp.300-310
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• 1997

편평상피세포암종은 악성종양 중 가장 중요한 비중을 차지하고 있는 암종이다. 하지만 편평상피세포암종의 세포주는 다른 악성종양에 비하여 아직까지 많이 개발되어지지 않았다. 또한 동물실험모델을 만들기 위한 이종이식에 있어서 편평상피세포암종은 매우 낮은 생착율을 보이고 있다. 구강암 중에서도 편평상피세포암종은 가장 많은 부분을 차지하나, 개발된 세포주는 그리 많지 않으며, 더 더욱이 동물실험 모델의 제작은 쉽지 않아, 새로운 치료 약제의 개발이나 치료 방법 개발 등에 많은 제약이 있어왔다. 본 실험에서는 수종의 구강 편평상피세포암종의 세포주를 배양하였고, 특별히 고안된 사육시설을 이용하여 BALB/C nude mice를 사육하였다. 여러 농도의 구강암 세포주를 nude mice의 등에 피하로 이식하였다. 어떤 세포주는 계속적인 성장을 보였으나 어떤 세포주는 완전히 흡수되기도 하였다. 5주 이상을 관찰하였으며, 이식된 종양의 크기를 측정하고, 부피를 계산하였다. 또한 또 다른 동물모델의 제작 방법으로서 특별히 고안된 cap을 nude mice의 등에 이식하고, 그 안에 구강암 세포주를 배지와 함께 이식하였으며, 1주 후에 cap을 제거하였고, 4주 이상을 관찰하였으며, 성장하는 종양의 모습과 크기를 관찰하였다. 본 연구는 구강암 연구에 적절한 동물실험모델을 개발하여 다른 악성종양에 비해 동물실험적으로 연구할 기회가 적었던 구강암 영역의 연구를 활발히 하며, 향후 한국인의 구강암연구에 가장 적절한 동물실험모델을 개발하여, 보다 진보된 구강암 치료방법의 개발 및 신약 등의 개발에 이용하기 위함이다.

• 한국ITS학회 논문지
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• 제12권6호
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• pp.22-28
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• 2013

본 연구에서는 대전광역시를 대상으로 향후 카쉐어링 서비스를 제공할 경우를 가정하고 위치 선정방안을 제시하는 것을 목적으로 한다. 이를 위해 GIS Arc/Info 10 소프트웨어를 활용하여 대전광역시 전역을 $500m{\times}500m$ 크기의 셀로 구분하고 카쉐어링 서비스에 영향을 미칠 것으로 예상되는 요인들을 선정하고 각 요인들의 값을 표준화하는 과정을 거쳤다. AHP 기법을 도입하여 각 요인별 가중치를 전문가 설문을 통해 결정하고 모든 셀($500m{\times}500m$ 크기)별로 적합도 지수를 산정하였으며, 네트워크 분석(Network Analysis)모듈에 내장되어있는 입지배분모델(Location-allocation Model)을 이용하여 서비스 시설의 위치를 30개의 권역으로 선정하는 방안을 제시하였다. 본 연구에서 제안한 카쉐어링 서비스 위치선정을 위한 방안은 향후 카쉐어링 서비스가 도입될 때 기초 자료로 활용할 수 있을 것으로 기대되며, 향후 적정한 수요의 추정과 경제성 검토 등에 대한 추가연구가 필요할 것으로 판단된다.

• 한국수산과학회지
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• 제51권1호
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• pp.31-41
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• 2018

Seaweeds are composed of a variety of bioactive substances, including polysaccharides, pigments, minerals, peptides, and polyphenols. Among these substances, the arsenic content of seaweeds has been a significant cause for concern. The present study evaluated the toxicity of arsenic from three species of seaweed using a zebrafish Danio rerio model. The arsenic-rich extracts were obtained from Ecklonia cava (ECAE), Undaria pinnatifida (UPAE) and Hizikia fusiformis (HFAE) using a solvent of 50% methanol and 1% $HNO_3$. We investigated the toxicity of the arsenic-rich extracts in zebrafish embryos through survival rate, heart rate, yolk sac edema size, cell death, reactive oxygen species (ROS) production and real-time polymerase chain reaction (PCR). The hepatotoxicity of arsenic-rich extracts was assessed in the liver of adult zebrafish through real-time PCR and histopathology. The survival rates of embryos and adult zebrafish showed no significant changes at any concentration. At 100 ppm, embryos did not exhibit significant differences in heart rate, yolk sac edema size, cell death or ROS production. In addition, apoptosis-related genes in larvae and liver tissue were unaffected by treatment with arsenic-rich extracts. These data will help clarify that developmental changes, hepatic oxidative stress, and apoptosis are not associated with toxicity from arsenic-rich seaweed extracts in a zebrafish model.

• 한국식품영양과학회지
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• 제36권4호
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• pp.400-404
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• 2007

흰쥐 우측요부에 RK3E-ras cell주입으로 7일 이내에 종양이 발달하는 것을 관찰하고, 단삼 추출물을 제조하여 항종양 효과를 관찰하고자 1주 후부터 2주 동안 육종 부위에 투여 후 종양의 크기와 무게를 측정하고 조직학적인 관찰을 통하여 암세포의 발달과 암전이 유무를 살펴보았다. 암종의 크기는 대조군에 비하여 단삼 추출물을 투여한 실험군에서 현저히 감소(p<0.01)하였으며, 암종의 중량 또한 실험군에서 현저히 감소(p<0.01)하였다. 조직학적 관찰 결과 종양을 둘러싸고 있는 섬유막은 대조군에 비하여 실험군에서 발달 해 있었으며, 암세포의 밀도는 실험군에 비하여 대조군에서 높았다. 간조직을 관찰한 결과 대조군의 간문맥 주변에서 전이된 것으로 보이는 암세포들이 다수 관찰되었다. 이와 같은 결과를 토대로 단삼 추출물이 항종양효과가 있다고 사료된다.

• 한국수소및신에너지학회논문집
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• 제18권4호
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• pp.422-431
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• 2007

Polymer electrolyte membrane fuel cell(PEMFC) is very interesting power source due to high power density, simple construction and operation at low temperature. But it has problems such as high cost, improvement of performance and effect of temperature. These problems can be approached to be solved by using mathematical models which are useful tools for analysis and optimization of fuel cell performance and for heat and water management. In this paper, the present work is to develop an electrochemical model to examine the electrochemical process inside PEM fuel cell. A complete set of considerations of mass, momentum, species and charge is developed and solved numerically with proper account of electrochemical kinetics. When depth of gas channel becomes thinner, diffusion of reactant makes well into gas diffusion layer(GDL) and the performance increases. Although at low current region there is little voltage difference between experimental data of PEM fuel cell and numerical data. When the porosity size of gas diffusion layer for PEM fuel cell is bigger, oxygen diffusion occurs well and oxygen mass fraction appears high in catalyst layer.