• 한국미생물·생명공학회지
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• 제22권3호
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• pp.240-245
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• 1994

Relation the phage defense mechanism of phage resistant Lactococcus lactis subsp. cremoris ATCC 11602-A1 to its cell wall components was investigated. To determine whether teichoic acid which is known to be one of the phage receptor site present on the cell wall, phage adsorption was examined after treatment 5% TCA(60%$\CIRC $C) and concanavalin A to the cell wall of A1 and parent strain. However, the adsorption rate of two strains did not change. Total amount of phosphate after TCA treatment did not change in both strains, but a difference between the two strains was observed. Ribitol and glycerol, components of teichoic acid, could not be detected in the cell walls of two strains by GC analysis. These results suggest that although teichoic acid was not present in the cell walls of both strains, the composition of cell wall of two strains was not identical. Measurement of amount of protein and SDS-polyacryamide gel electrophoresis were carried out to examine the involvement of cell wall protein in phage resistance, showing that protein is nothing to do with phage adsorption of parent strain, but phage resistance of A1 is related to protein. Cell wall carbohydrates of A1 contained rhamnose, glucose, and galactose. Total amount of carbohydrate of 1% SDS-treated A1 cell wall was reduced to the level of parent strain. The results suggest that phage resistance of A1 was due to the presence of a higher level of carbohydrates then parent strain, and to interaction of carbohydrate and protein.

• Genomics & Informatics
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• 제10권1호
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• pp.23-32
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• 2012

There are lots of studies attempting to identify the expression changes in oral squamous cell carcinoma. Most studies include insufficient samples to apply statistical methods for detecting significant gene sets. This study combined two small microarray datasets from a public database and identified significant genes associated with the progress of oral squamous cell carcinoma. There were different expression scales between the two datasets, even though these datasets were generated under the same platforms - Affymetrix U133A gene chips. We discretized gene expressions of the two datasets by adjusting the differences between the datasets for detecting the more reliable information. From the combination of the two datasets, we detected 51 significant genes that were upregulated in oral squamous cell carcinoma. Most of them were published in previous studies as cancer-related genes. From these selected genes, significant genetic pathways associated with expression changes were identified. By combining several datasets from the public database, sufficient samples can be obtained for detecting reliable information. Most of the selected genes were known as cancer-related genes, including oral squamous cell carcinoma. Several unknown genes can be biologically evaluated in further studies.

• 한국환경성돌연변이발암원학회지
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• 제26권1호
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• pp.1-6
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• 2006

To enhance our understanding of toxicity mediated through the pathway by which TCDD stimulates gene expression, we have investigated genes whose expressions are changed after treatment with TCDD and/or MNNG in human Chang liver cell. First, we treated with MNNG and TCDD for two weeks to transform human Chang liver cell. We obtained cell looks like to be transformed and compared the differential gene expression by using cDNA chip (Macrogen) which carrys genes related with signal transduction pathways, oncogenes and tumor suppressor genes, etc. We found that TCDD up- or down-regulated 203 and 111 genes including oncogenes and tumor suppressor genes in human Chang liver cell two fold or more, respectively. Second, we compared the differential gene expression after treatment with TCDD only by using cDNA chip (Superarray) which carrys genes related with cell cycle regulations, and found that TCDD up regulated genes related with cell proliferation as well as cell growth inhibition in human Chang liver cell two fold or more, respectively. These results suggest that toxicity induced by TCDD may reflect sustained alterations in the expression of many genes and that the changes reflect both direct and indirect effects of TCDD.

• Journal of Mechanical Science and Technology
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• 제19권4호
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• pp.1018-1026
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• 2005

The proton exchange membrane (PEM) fuel cell system consisting of stack and balance of plant (BOP) was modeled in a MATLAB/Simulink environment. High-pressure operating (compressor type) and low-pressure operating (air blower type) fuel cell systems were con­sidered. The effects of two main operating parameters (humidity and the pressure of the supplied gas) on the power distribution characteristics of BOP and the net system efficiency of the two systems mentioned above were compared and discussed. The simulation determines an optimum condition regarding parameters such as the cathode air pressure and the relative humidity for maximum net system efficiency for the operating fuel cell systems. This study contributes to get a basic insight into the fuel cell stack and BOP component sizing. Further research using muli­object variable optimization packages and the approach developed by this study can effectively contribute to an operating strategy for the practical use of fuel cell systems for vehicles.

• 대한수의학회지
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• 제30권4호
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• pp.355-360
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• 1990

포유동물의 초기 발생단계에서 핵의 분화와 전능성(totipotency) 을 규명하고, 수정란의 cloning technique를 개발하여 우량유전자로 조성된 개체를 복제함으로써 효과적인 종축개량 기법으로 응용하기 위하여 생쥐 수정란을 모델로 하여 미세조작기법과 Sendai virus를 이용한 핵융합기술을 이용하여 인위적으로 동일한 유전자를 가진 복제 수정란을 작출하고 이들의 작출효과, 체외발달능력 및 체내 이식후 개체발생여부 등을 조사하였다. 2-세포기, 4-세포기 및 8-세포기의 수정란으로부터 핵을 채취하여 이들을 탈핵된 2-세포기의 수정란에 이식하였을 때, 이들의 핵융합 성공율은 각각 88.6%, 87.1% 및 84.7%이었다. 나아가서 이들 핵융합된 수정란을 체외에서 96시간 배양한 결과, 2-세포기, 4-세포기 및 8-세포기의 핵이 이식된 수정란은 각각 76.5%, 68.4% 및 48.3%가 배반포로 발달하였다. 핵이식 후 체외에서 배반포로 발달된 수정란을 골라 수란생쥐에 이식하였던 바, 2-세포기의 핵이 이식된 수정란 156개 중 58개(37.1%) 가 발달하여 신생자로 생산되었으며, 4-세포기의 핵아 이식된 수정란 135개 중 40개(29.6%)가, 그리고 8-세포기의 핵이 이식된 92개의 수정란 중 15개(16.3%)가 신생자로 생산되었다.

• Reproductive and Developmental Biology
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• 제31권3호
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• pp.193-198
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• 2007

본 연구는 소의 초기 난할 단계인 2 또는 4세포기 수정란의 특정 분할구가 배반포 단계의 내부 세포괴(Inner Cell Mass)와 영양막 세포(Trophectoderm cells)로의 발달 운명이 미리 정해지는 지를 확인하기 위해 실시되었다. 먼저 생쥐의 체내수정란과 소의 체외 수정란에서 배반포의 영양막 세포에서만 특이적으로 발현하는 cdx2단백질의 발현 양상을 조사하였다. 또한, 소의 경우 2세포기와 4세포기가 내부 세포괴와 영양막 세포로 나눠지는 시점인지를 조사하기 위해 2 또는 4세포기의 특정 분할구에 Dextran의 주입 실험과 분할구 제거 실험을 통해 ICM과 TE 형성을 확인하였다. cdx2의 발현 경향은 생쥐와 소의 2세포기일 때 대칭과 비대칭적으로 발현되는 것을 확인하였다. 생쥐의 4, 8세포기 및 상실배기에서는 분할구 전체에서 발현되었으나, 소 수정란의 분할구에서는 전체 또는 부분적으로 발현되었다. 또한, 생쥐와 소의 배반포기에서는 영양막 세포에서만 발현이 되는 것을 확인하였다. 소 수정란의 2세포기와 4세포기 단계에서 특정 분할구에 주입된 De xtran은 배반포의 내부 세포괴와 영양막 세포의 양쪽에 분포된 것을 관찰할 수 있었다. 2세포기 단계에서 하나의 분할구가 제거된 수정란 역시 ICM 및 TE 세포를 지닌 정상 배반포로 발달함을 확인하였다. 따라서 본 연구 결과는 영양막 세포에서만 특이적으로 발현하는 cdx2의 발현이 2 또는 4세포기 단계 소 수정란에서는 특별한 차이를 보이지 않으며, 궁극적으로 난할 초기에는 ICM과 TE 세포로의 운명이 결정되지 않는다는 것을 보여준다.

• 한국동물학회지
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• 제36권2호
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• pp.277-284
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• 1993

A possible involvement of maturation promoting factor (nfPF) in the two-cell block phenomenon was studied by fusion experiments. Germinal vesicle (GlF) ooeyte was fused with a blastomore from late or blocked 2-cell mouse embryos. and germinal vesicle breakdoum (GVBD) of fused GV oocvtes in the presence of dbcAMP (100$\mu$g/ml) was scored as an index of MPF aniviD. GnD was induced approximately 30% by fusion of a blastomere derived from late 2-cell embryos, but not from blocked 2-cell embryos. The rate of GVBD was changed when GV oocyte was fused with a blastomere from late 2-cell embryos which were treated with u-amanitin, puromvcin or colcemid before and after hsion: Treatment of late 2-cell embryos with puromycin (50 Is/mll but not with u-amanitin (100 Is/ml) clearly inhibited GVBD, indicating that do novo protein synthesis maw be required for the appearance of MPF activity in late 2-cell embryos. Treatment of late 2-cell embryos w기h colcemid (0.1 Is/mll doubled GVBD, presumably due to the maintenance of metaphase or mitotic phase. SDS-PAGE and twoiimensional electrophoresis revealed that there was no difference in protein synthetic pattern in late and blocked 2-cell embryos, but three phosphoproteins with 27, 35 and 46 M)a, presumsblv M-phase components were phosphorylated in late 2-cell embryos but not in blocked 2-cell embryos. It seems then that MPF activity is closely related to phosphorylstion of M-phase components in late 2-cell embryos.

• 한국통신학회논문지
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• 제22권4호
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• pp.855-869
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• 1997

In this paper, we proposed two kids of dynamic priority control mechanisms controlling the cell service ratio in order to improve the QOS(Quality of Service). We also analyse theoretically the characteristics of cell loss probability and mean cell delay time by applying the proposed priority control mechanisms to ATM switch with output buffer. The proposed priority control mechanisms have the same principles of storing cells into buffer but the different principles of serving cells from buffer. The one is the control mechanism controlling the cell service ratio according to the relative cell occupancy ratio of buffer, the other is the control mechanism controlling the cell service ratio according to both the relative cell occupancy ratio of buffer and the average arrival rate. The two service classes of our concern are the delay sensitive class and the loss sensitive class. The analytical results show that the proposed control mechanisms are able to improve the QOS, the characteristics of cell loss probability and mean cell delay time, by selecting properly the relative cell occupancy ratio of buffer and the average arrival rate. conventional DLB algorithm does not support synchronous cells, but the proposed algorithm gives higher priority to synchronous cells. To reduce synchronous cell loss rate, the synchronous cell detector is used in the proposed algorithm. Synchronous cell detector detects synchronous cells, and passes them cells to the 2nd Leaky-Bucket. So it is similar to give higher priority to synchronous cells. In this paper, the proposed algorithm used audio/video traffic modeled by On/Off and Two-state MMPP, and simulated by SLAM II package. As simulation results, the proposed algorithm gets lower synchronous cell loss rate than the conventional DLB algorithms. The improved DLB algorithm for multimedia synchronization can be extended to any other cells which require higher priority.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2005년도 International Meeting on Information Displayvol.I
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• pp.446-449
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• 2005

The alignment property of liquid crystals on the two-easy axes substrate is investigated. The two-easy axes substrate frustrates the orientation of the LCs next to the substrate, and hence influences the birefringence of the LC cell. Experimental findings reveal that the ratio of the rubbing strengths in the different rubbing directions and the cell thickness substantially influence the birefringence of the LC cell. The surface anchoring energetic competition between the different rubbing directions contributes to the observed results.

• 한국복합재료학회:학술대회논문집
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• 한국복합재료학회 2005년도 춘계학술발표대회 논문집
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• pp.187-190
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• 2005

A simple beam model based on a mixed method is proposed for the analysis of thin-walled composite blades with a two-cell airfoil section. A semi-complementary energy functional is used to obtain the beam force-displacement relations. The theory accounts for the effects of elastic couplings, shell wall thickness, warping, and warping restraint. All the kinematic relations as well as the cross-section stiffnesses are evaluated in a closed-form through the current beam formulation. The theory has been applied to two-cell composite blades with extension-torsion couplings and fairly good correlation has been observed in comparison with a detailed analysis and other literature.