• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2002년도 춘계학술대회 논문집
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• pp.890-893
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• 2002

This study is focused to predict the behavior of Al foam with closed-cell structure during the 3 point bending test and the upsetting test according to aspect ratio. We calculated characters of aluminum foams with closed-cell structure and took the simulation. The effects on the aspect ratio of the cell was investigated parametrically. The analysis was carried out on two models, First, the bending test in elasticity of the rectangular beam, and Second, the upsetting test in plasticity of the circular cylinder. In the analysis, the deformation of the beam and the cylinder was influenced by the aspect ratio of the cell. Further, We assumed that the geometry of feared aluminum cell change the stress and strain in the test.

• Journal of Information Processing Systems
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• 제16권1호
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• pp.113-119
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• 2020

This study proposed the structure of the cluster's cell counting algorithm for cell analysis. The image required for cell count is taken under a microscope. At present, the cell counting algorithm is reported to have a problem of low accuracy of results due to uneven shape and size clusters. To solve these problems, the proposed algorithm has a feature of calculating the number of cells in a cluster by applying a radius change analysis to the existing distance conversion and watershed algorithm. Later, cell counting algorithms are expected to yield reliable results if applied to the required field.

• Applied Microscopy
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• 제36권spc1호
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• pp.47-56
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• 2006

Improvements are made to existing primitive cell volume measurement method to provide a real-time analysis capability for the phase analysis of nanocrystalline materials. Simplification is introduced in the primitive cell volume calculation leading to fast and reliable method for nano-phase identification and is applied to the phase analysis of Mo-Si-N nanocoating layer. In addition, comparison is made between real-time and film measurements for their accuracy of calculated primitive cell volume values and factors governing the accuracy of the method are determined. About 5% accuracy in primitive cell determination is obtained from camera length calibration and this technique is used to investigate the cell volume variation in WC-TiC core-shell microstructure. In addition to chemical compositional variation in core-shell type structure, primitive cell volume variation reveals additional information on lattice coherency strain across the interface.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2005년도 제36회 하계학술대회 논문집 B
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• pp.1722-1724
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• 2005

The focus of this paper is to develop a mathematical model for investigating the dynamic performance of a polymer electrolyte membrane fuel cell. The model in this work is based on physical laws having clear significance in replicating the fuel cell system and can easily be used to set up different operational strategies. Simulation results display the transient behavior of the voltage within each single cell, and also within a number of such single cells combined into a fuel cell stack system. A linear as well as a nonlinear analysis of the polymer electrolyte membrane fuel cell system(PEMFC) has been discussed in order to present a complete and comprehensive view of this kind of modeling. Also, a comparison of the two kinds of analysis has been performed. Finally, the various characteristics of the fuel cell system are plotted in order to help us understand its dynamic behavior. Results indicate that there is a considerable amount of error in the modeling process if we use a linear model of the fuel cell. Thus, the nonlinearities present in the fuel cell system should be taken into account in order to obtain a better understanding of the dynamic behavior of the fuel cell system.

• 한국전자파학회논문지
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• 제19권7호
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• pp.791-799
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• 2008

본 논문에서는 $DC{\sim}18\;GHz$에서 동작하는 GTEM 셀 설계를 위한 전자파 모델링과 회로망 해석 기법을 제시하였다. GTEM 셀의 동축선 입력 급전부의 모드 변환기, 전송선 길이가 5미터인 확장형 사각 동축선 그리고 전송부 동축선의 전류와 입력단으로부터 입사되는 전자파를 정합시킬 수 있는 종단 부하로 구성되는 3차인 전자파 수치 해석 모델을 제시하였다. GTEM cell의 급전부, 전송선부, 종단 부하부에 대한 등가 회로망 모델을 제시하였으며, 이를 이용하여 전자파 수치 해석 모델에서 구해진 산란 계수로부터 GTEM cell의 성능 평가 지수인 입력 반사 계수를 계산할 수 있도록 하였다. $DC{\sim}18\;GHz$에서 동작하는 $5.0{\times}2.5{\times}1.7\;m$ 크기의 GTEM cell을 설계, 제작, 성능 평가하여 제안한 기법의 효용성을 입증하였다.

• Parasites, Hosts and Diseases
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• 제57권2호
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• pp.185-189
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• 2019

To identify the component(s) involved in cell cycle control in the protozoan Giardia lamblia, cells arrested at the G1/S- or G2-phase by treatment with nocodazole and aphidicolin were prepared from the synchronized cell cultures. RNA-sequencing analysis of the 2 stages of Giardia cell cycle identified several cell cycle genes that were up-regulated at the G2-phase. Transcriptome analysis of cells in 2 distinct cell cycle stages of G. lamblia confirmed previously reported components of cell cycle (PcnA, cyclin B, and CDK) and identified additional cell cycle components (NEKs, Mad2, spindle pole protein, and CDC14A). This result indicates that the cell cycle machinery operates in this protozoan, one of the earliest diverging eukaryotic lineages.

• 한국산학기술학회논문지
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• 제19권6호
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• pp.600-613
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• 2018

본 연구에서는 "플렉시블 태양 전지(Flexible Solar Cell)"에 대한 학술 문헌(논문) 데이터 베이스를 대상으로 네트워크 분석을 진행하고 이를 바탕으로 "플렉시블 태양 전지(Flexible Solar Cell)"의 최근 연구 동향을 분석하였다. 네트워크 분석에 사용된 데이터는 2013년부터 2017년까지의 최근 5년 간의 학술 논문을 대상으로 하였으며, 주요 분석 기법으로는 키워드 빈도 수 출현 기반 분석 및 중심성 분석 (연결 정도 중심성, 근접 중심성, 매개 중심성)을 적용하였다. 네트워크 분석 결과, "전지(cell)"은 중심성 척도가 0.8 이상으로, 전체 키워드 중 80% 이상과 연결되어 있어, 플렉시블 태양 전지 (Flexible Solar Cell) 분야의 연구 중심으로 식별이 되었다. "페로브스카이트(Perovskite)"와 "CIGS(CuInGaSe2)"는 "전지(cell)"의 하위 그룹의 중심으로 식별되었다. 이러한 분석 결과는 최신 기술인 "CIGS/페로브스카이트 탠덤 태양 전지"를 의미하고 있음을 확인 할 수 있었다. 향후 분석 기법을 보다 최적화/정교화하게 된다면 현재의 기술 동향 예측을 통해서 관련 연구 분야의 기술기획 및 연구 방향성 제시에 큰 도구로 활용 될 것이라 기대한다.

• Reproductive and Developmental Biology
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• 제34권3호
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• pp.143-151
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• 2010

Pluripotency of human embryonic stem cell (hESC) is one of the most valuable ability of hESCs for applying cell therapy field, but also showing side effect, for example teratoma formation. When transplant multipotent stem cell, such as mesnchymal stem cell (MSC) which retains similar differentiation ability, they do not form teratoma in vivo, but there exist limitation of cellular source supply. Accordingly, differentiation of hESC into MSC will be promising cellular source with strong points of both hESC and MSC line. In this study, we described the derivation of MSC like cell population from feeder free cultured hESC (hESC-MSC) using direct differentiation system. Cells population, hESC-MSC and bone marrow derived MSC (BM-MSC) retained similar characteristics in vitro, such as morphology, MSC specific marker expression and differentiation capacity. At the point of differentiation of both cell populations, differentiation rate was slower in hESC-MSC than BM-MSC. As these reason, to verify differentially expressed molecular condition of both cell population which bring out different differentiation rate, we compare the molecular condition of hESC-MSC and BM-MSC using 2-D proteomic analysis tool. In the proteomic analysis, we identified 49 differentially expressed proteins in hESC-MSC and BM-MSC, and they involved in different biological process such as positive regulation of molecular function, biological process, cellular metabolic process, nitrogen compound metabolic process, macromolecule metabolic process, metabolic process, molecular function, and positive regulation of molecular function and regulation of ubiquitin protein ligase activity during mitotic cell cycle, cellular response to stress, and RNA localization. As the related function of differentially expressed proteins, we sought to these proteins were key regulators which contribute to their differentiation rate, developmental process and cell proliferation. Our results suggest that the expressions of these proteins between the hESC-MSC and BM-MSC, could give to us further evidence for hESC differentiation into the mesenchymal stem cell is associated with a differentiation factor. As the initial step to understand fundamental difference of hESC-MSC and BM-MSC, we sought to investigate different protein expression profile. And the grafting of hESC differentiation into MSC and their comparative proteomic analysis will be positively contribute to cell therapy without cellular source limitation, also with exact background of their molecular condition.

• 대한한방내과학회지
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• 제26권1호
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• pp.48-59
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• 2005

Objectives : The aim of the study was to evaluate the effect of WS on HepG2 cell cycle and expression of related genes. Methods : The MTT assay, Cell counting analysis, $[^3H]-Thymidine$ Incorporation Assay, Flow cytometric analysis, Quantitative RT-PCR were studied. Results : WS inhibited HepG2 cell proliferation in low concentration$(1-10\;{\mu]g/ml)$ which did not cause direct cytotoxicity, with dose-dependant manner. WS in-hibited DNA synthesis as well. Flow cytometric analysis on the HepG2 cell showed G2/M phase arrest. Conclusion : These results suggest that WS inhibits HepG2 cell proliferation not by the gene regulation but by G2/M phase arrest in the cell cycle. Thus further studies on the effect of WS in G2/M phase regulation are thought to be needed.

• 대한물리치료과학회지
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• 제10권1호
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• pp.198-205
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• 2003

We evaluated the effect of low power GaAsAl laser on re-epithelization in full-thickness excisional wound of rat skin. Two full-thickness excisions were made on the back of the experimental animals. Low power laser applications with 10mW intensity were treated experimental animals twice a day for 7 days. On the seventh postoperative day the quantitative analysis of re-epithelization was performed using immunohistochemical staining for proliferating cell nuclear antigen (PCNA). The majority of PCNA immunoreactive cells was observed at epithelial cells in the margin of full thickness excisional wound. The low power laser treatments significantly increased the number of PCNA immunoreactive cell as compared to that of non treated animal group (p<0.01). The shape of PCNA immunoreactive cell appeared as small dark, round to ovoid structures. Most PCNA immunoreactive cells exhibited a high intensity of staining that contrasted sharply with the surrounding background. In conclusion, these findings suggest that GaAlAs laser treatments effectively enhance the epithelial wound healing by the stimulating cell proliferation. Furthermore, the majority of cell proliferation occurred in the margin of full thickness excisional wound.