• 대한생식의학회:학술대회논문집
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• 대한생식의학회 2007년도 제53차 추계학술대회 초록집
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• pp.124.1-124.1
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• 2007

• Reproductive and Developmental Biology
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• 제30권4호
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• pp.279-285
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• 2006

Vitrification has been suggested to be an effective method for the cryopreservation of human ES cells. However, the efficiency of vitrification with different vehicles remains a matter of ongoing controversy. The objective of this study was to assess the efficiency of cryopreservation in human ES cells by vitrification using different vehicles. A human ES cell line and a variety of vehicles, including micro-droplet (MD), open-pulled straw (OPS) and electron microscopic grid (EM-grid), were employed in an attempt to assess vitrification efficiency. In order to evaluate the survivability and the undifferentiated state of the post-vitrified human ES cells, we conducted alkaline phosphatase staining and characterization via both RT-PCR and immunofluorescence assays. The survival rates of the post-vitrified human ES cells using MD, OPS and EM-grid were determined to be 61.5%, 66.6% and 53.8%, respectively. There also exist significant differences between slow-freezing and vitrification (p<0.01). However, no significant differences were detected between the vehicle types. Finally, the pluripotency of human ES cells after thawing was verified by teratoma formation. Cryopreservation using vitrification is more effective than slow-freezing, and the efficiency of vehicles proved effective with regard to the preservation of human ES cells.

• 과학교육연구지
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• 제45권1호
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• pp.11-22
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• 2021

이 연구의 목적은 국제 STEM 교육 분야의 연구 결과를 종합하여 국제 STEM 교육의 주요 이슈를 파악하는 데 있다. 이 연구의 분석 대상 자료는 선정 기준과 전문가 그룹의 검토를 통해 다양한 STEM 교육의 이슈를 반영하고 있는 메타분석 또는 체계적 문헌연구의 결과이다. 총 23개의 연구를 대상으로 질적 메타 분석을 하여 다음과 같은 STEM 교육의 이슈를 선정하였다. 첫째, STEM 교육은 국제적인 교육 동향으로 미국, 캐나다, 호주, 한국, 터키 등 많은 국가에서 연구되고 있다. 둘째, STEM 교육은 학생들의 인지적, 정의적, 심동적, 그리고 진로 영역의 향상에 긍정적으로 기여하고 있다. 셋째, STEM 교육은 다양한 수업 도구와 기술의 사용과 함께 연구되어 왔다. 또한, STEM 교육에 대한 교사의 전문성 신장이 성공적인 STEM 교육의 실현의 주요 요인들 중 하나이다. 그 외에 STEM 교육의 성공적인 실천을 위해 다양성, 평등, 타당하고 신뢰로운 연구 설계 등의 이슈에 대해 논의하였다. 또한 이 연구는 우리나라 융합교육의 방향과 실천 전략을 위한 함의점을 제공할 수 있으며 향후 연구에 대한 제언을 줄 수 있다.

• 대한생식의학회:학술대회논문집
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• 대한생식의학회 2007년도 제52차 춘계학술대회 초록집
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• pp.124-124
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• 2007

• 대한생식의학회:학술대회논문집
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• 대한생식의학회 2007년도 제52차 춘계학술대회 초록집
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• pp.122-122
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• 2007

• 대한생식의학회:학술대회논문집
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• 대한생식의학회 2007년도 제52차 춘계학술대회 초록집
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• pp.126-126
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• 2007

• IMMUNE NETWORK
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• 제1권3호
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• pp.179-186
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• 2001

Bone marrow stroma is a complex tissue encompassing a number of cell types and supports hematopiesis, differentiation of erythreid, nyel and lymphoid lineages, and also maintains undifferentiated hematopoietic stem cells. Marrow-derived stem cells were composed of two populations, namely, hematopoietic stem cells that can differentiate into blood elements and mesenchymal stem cells that can give rise to connective tissues such as bone, cartilage, muscle, tendon, adipose and stroma. Differentiation requires environmental factors and unique intracellular signaling. For example, $TGF-{\beta}$ or BMP2 induces osteoblastic differentiation of mesenchymal stem are very exciting. However, the intrinsic controls involved in differentiation of stem cells are yet to be understood properly in order to exploit the same. This review presents an overview of the recent developments made in mesenchymal stem cell research with respect to osteogenesis.

• Nuclear Engineering and Technology
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• 제35권2호
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• pp.133-143
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• 2003

Stem-stem nut coefficient of friction(COF) in motor-operated gate/globe valves is one of the important factors which determine the performance of the valve/actuators. The COF is affected greatly by the type and condition of the stem-stem nut lubricants, environmental parameters, surface condition of the stem/stem-nuts, and the number of strokes after the lubrication. In this paper, the measured data of the COFs at stem threads of some safety-related motor-operated gate/globe valves in domestic nuclear power plants are presented. In addition, the performance of the lubricants is evaluated by comparing the COFs among those valves. The results show that the measured COF at torque switch trip are higher than the unwedging COF and conservatively applicable to the unwedging COF. It is also shown that the lubricating performance based on the measured COFs varies with the lubricants.

• Reproductive and Developmental Biology
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• 제30권4호
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• pp.287-291
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• 2006

We have developed a new passaging technique for the expansion of human embryonic stem cells (hESCs) that involves simply pipetting portions of hESCs acquired from colonies, reducing the laborious and time-consuming steps in the expansion of hESCs. Compared to general mechanical methods of passaging, our pipetting method allowed hESCs colonies to be broken into small fragments, which showed significantly higher attachment rates onto feeder cell layers. This technique produced three times the number of hESCs colonies than conventional mechanical methods. In addition, this pipetting method allowed us to distinguish differentiated hESCs from undifferentiated hESCs during hESCs colony pipetting. The hESCs cultured by pipetting method displayed normal human chromosomes for over 60 passages. According to RT-PCR and immunohistochemical analysis, the hESCs successfully maintained their undifferentiated state and pluripotency which was also confirmed by teratoma formation in viva Therefore, the pipetting method described in this study is a useful tool to efficiently and quickly expand hESCs on a large scale without enzyme treatment.

• 대한산업공학회지
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• 제41권5호
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• pp.488-498
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• 2015

Research on stem cells can be divided into three categories : pluripotent stem cell, adult stem cell, and induced pluripotent stem cell. Technology life cycle (TLC) on research stage is analyzed for the three stem cell categories based on diffusion model. Three diffusion models-logistic, Bass, and Bass model with integration constant (BMIC)-are applied to the number of articles related to each stem cell category in SCOPUS lists. Two different parameter estimation methods is used for each of logistic and Bass model. Results show that (1) the current year, 2015, lies in growth period at pluripotent stem cell and adult stem cell, and lies in growth period or maturity period at induced pluripotent stem cell. (2) Model fitness is the highest at BMIC model. (3) Imitation effect works best at the research area of induced pluripotent stem cell.