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임희대,임찬수,이성용 忠南大學校 産業技術硏究所 1995 산업기술연구논문집 Vol.10 No.2
Various modes of load transfer may exist in rockfill dams. If the core is softer than the shells, load is transferred from the core onto the shells as a result of greater downward displacement of the core with respect to the shells. But if the core is stiffer than the shells, load transfer occurs from the shells onto the core. In this study, the mechanisms of load transfer in rockfill dams have been outlined and load transfer of Juam main and regulation dam with central core are evaluated by load transfer ratio. The load transfer ratio is defined as the ratio of computed values of major principal stresses in the core to the core overburden stresses. The vertical stresses are determined by the FEM, which use hyperbolic model and incremental method to simulate placement of successive layers of fill. The hyperbolic paramaters for the core was estimated from a series of conventional triaxial tests carried out during construction. From the results of this analyses and its comparison with the values measured by soil pressure meters, it has been shown that significant load transfer from the core to the shells was observed in two dams and that the load transfer ratios predicted are higher than the values measured.
Assessment of Gas Generation in Underground Repository of Low-Level Waste
Cho, Chan-Hee,Kim, Chang-Lak,Lee, Myung-Chan,Park, Heui-Joo Korean Nuclear Society 1996 Nuclear Engineering and Technology Vol.28 No.1
In a repository containing low-level waste, gas generation will occur principally by the coupled processes of metal corrosion and microbial degradation of cellulosic waste. This paper describes a mathematical model designed to address gas generation by these mechanisms and assesses the potential effects of gas generation on the performance of a radioactive waste repository. The metal corrosion model incorporates a three-stage process encompassing aerobic and anaerobic corrosion regimes ; the microbial degradation model simulates the activities of eight different microbial populations, which are maintained as functions both of pH and of the concentrations of particular chemical species. A prediction is made for gas concentrations and generation rates over an assessment period of ten thousand years in a radioactive waste repository. The results suggest that H$_2$will be the principal gas generated within the radioactive waste cavern.
양찬호 ( Chan Ho Yang ),배유진 ( Yu Jin Bae ),김찬종 ( Chan Jong Kim ),최승언 ( Seung Urn Choe ),김희백 ( Heui Baik Kim ),유준희 ( June Hee Yoo ),이경우 ( Kyung Woo Yi ),계영희 ( Young Hee Kye ),노태희 ( Tea Hee Noh ) 한국초등과학교육학회 2013 초등과학교육 Vol.32 No.4
In this study, we investigated science-related activities in everyday life perceived by elementary school students, and their preference and participation in the activities. We also analyzed the differences by student`s gender and interest in science. We developed a questionnaire of what activities elementary school students participated in daily experiences and how they perceived the connections of the activities with science. The questionnaire that was asked to rate the degrees of science-relatedness, preference, and participation of 35 activities was administered to fifth graders. The analysis of the results revealed that they perceived various everyday activities in their home and community as well as school were related to science. They generally preferred and participated in the activities. Boys perceived some activities, such as building things with magnets, Legos, or other toy and tools, more closely related to science, and the degrees of their preference and participation in these activities were higher than those of girls. It was also found that the students who were more interested in science not only perceived more activities related to science but also preferred and participated in the activities more. Educational implications of these findings are discussed.
연구논문 : 과학 관련 활동에 대한 초등학생의 선호 및 참여와 관련된 요인 탐색
양찬호 ( Chan Ho Yang ),조준모 ( Jun Mo Jo ),김찬종 ( Chan Jong Kim ),최승언 ( Seung Urn Choe ),김희백 ( Heui Baik Kim ),유준희 ( June Hee Yoo ),이경우 ( Kyung Woo Yi ),계영희 ( Young Hee Kye ),노태희 ( Tae Hee Noh ) 한국초등과학교육학회 2014 초등과학교육 Vol.33 No.3
In this study, we explored the factors related with preference for and participation in science-related activities of elementary school students. We developed a questionnaire to measure the characteristics of students such as motivation toward science learning, science aspiration, family science orientation, parental educational level and occupation, and the degrees of preference and participation of science-related activities. The questionnaire was administered to about 400 fourth graders in Seoul. The results revealed that the students with higher motivation toward science learning and/or science aspiration preferred and participated more in most activities. It was also found that parental educational level and occupation did not make an appreciable difference in preference and participation. The students who perceived their parents to be science-oriented, however, preferred and participated more in most activities. These results may offer practical implications for effective uses of both school and out-of-school science activities in elementary science education.
황희찬(Heui-Chan Hwang),채현석(Hyun-Suk Chae),최명렬(Myung-Ryul Choi) 한국정보과학회 2001 한국정보과학회 학술발표논문집 Vol.28 No.2Ⅲ
본 논문에서는 설치가 용이하고, 이동이 자유로우며 능동적으로 연결을 맺을 수 있는 무선 LAN환경 특성에 대해 알아보고, 무선LAN에서의 TCP 버전별 특성을 분석해 보았다. 또한 지연과 오류 확률이 높은 무선 LAN 환경에서 여러 가지 버전의 TCP가 동시에 사용되는 경우에 각 TCP 버전의 트래픽 특성을 모의 실험하였다. 이 실험을 위해 가장 많이 사용되어지고 있는 네트워크 시뮬레이터2(NS2)를 이용하였다.
Kim, Ki Chan,Go, Hyo Sang,Bak, Hae Rang,Choi, Chang Soon,Choi, Inha,Kim, Pitna,Han, Seol-Heui,Han, So Min,Shin, Chan Young,Ko, Kwang Ho BioMed Central 2010 JOURNAL OF BIOMEDICAL SCIENCE -BASEL- Vol.17 No.1
<P><B>Background</B></P><P>Prenatal ethanol exposure during pregnancy induces a spectrum of mental and physical disorders called fetal alcohol spectrum disorder (FASD). The central nervous system is the main organ influenced by FASD, and neurological symptoms include mental retardation, learning abnormalities, hyperactivity and seizure susceptibility in childhood along with the microcephaly. In this study, we examined whether ethanol exposure adversely affects the proliferation of NPC and de-regulates the normal ratio between glutamatergic and GABAergic neuronal differentiation using primary neural progenitor culture (NPC) and <I>in vivo </I>FASD models.</P><P><B>Methods</B></P><P>Neural progenitor cells were cultured from E14 embryo brain of Sprague-Dawley rat. Pregnant mice and rats were treated with ethanol (2 or 4 g/kg/day) diluted with normal saline from E7 to E16 for <I>in vivo </I>FASD animal models. Expression level of proteins was investigated by western blot analysis and immunocytochemical assays. MTT was used for cell viability. Proliferative activity of NPCs was identified by BrdU incorporation, immunocytochemistry and FACS analysis.</P><P><B>Results</B></P><P>Reduced proliferation of NPCs by ethanol was demonstrated using BrdU incorporation, immunocytochemistry and FACS analysis. In addition, ethanol induced the imbalance between glutamatergic and GABAergic neuronal differentiation <I>via </I>transient increase in the expression of Pax6, Ngn2 and NeuroD with concomitant decrease in the expression of Mash1. Similar pattern of expression of those transcription factors was observed using an <I>in vivo </I>model of FASD as well as the increased expression of PSD-95 and decreased expression of GAD67.</P><P><B>Conclusions</B></P><P>These results suggest that ethanol induces hyper-differentiation of glutamatergic neuron through Pax6 pathway, which may underlie the hyper-excitability phenotype such as hyperactivity or seizure susceptibility in FASD patients.</P>
A Numerical Study on the Thermal Behavior Evaluation of Bentonite Buffer
Chan-Hoon Yoon,Young-Chul Choi,Heui-Joo Choi 한국방사성폐기물학회 2015 방사성폐기물학회지 Vol.13 No.2
본 연구에서는 고준위폐기물 처분시 완충재로 사용되는 벤토나이트의 열적 거동을 평가하기 위해 실내실험 장치를 제작하였다. 그리고 실험 결과를 검증하기 위해 유한요소해석 프로그램인 ABAQUS를 이용한 열해 석을 실시하였다. 그리고 실험기간 동안의 계절변화를 감안하여 외부대기 온도에 따른 벤토나이트의 열적 거동을 평가하였다. 해석결과, 스테인리스스틸이 포함된 case3 해석모델의 결과가 실험결과와 1℃ 내외의 오차를 보이며 거의 일치함을 볼 수 있었다. 그리고 계절에 따른 벤토나이트 온도 해석을 수행한 결과, 시간 에 따른 온도분포 경향이 일치함을 확인하였다. 이러한 열해석을 통해 완충재를 둘러싸고 있는 물질의 열전 도도와 외부대기의 온도가 벤토나이트 완충재의 열적 거동에 큰 영향을 주는 요소임을 확인할 수 있었다. 향후 열원을 포함한 벤토나이트 완충재의 수분 포화 특성 실험이 실시 될 예정이므로, 실험에 대한 검증과 예측을 위해 보다 적합한 수치해석모델 개발에 대한 연구가 필요할 것이다. In this study, laboratory test equipment was designed and installed to evaluate the thermal behavior of bentonite, which is used as a buffer in high-level waste disposal systems. The thermal analysis was conducted to verify the test results using ABAQUS, a finite element analysis code. In view of the seasonal changes seen during the test, the thermal behavior of bentonite with a temperature of outside air was evaluated. Of the cases examined, the results of the analysis model using stainless steel (Case 3) approximates to the test results, showing an error of about 1℃. The results of the thermal analysis into seasonal temperature distributions are consistent with trends seen in lab-test results. These analyses show that the effects of the thermal conductivity of the material surrounding the buffer and outside air temperature, are very important factors in the thermal behavior of bentonite. In the future, it is expected that a moisture saturation test of a bentonite buffer containing a heat source will be carried out. Therefore, the development of a numerical analysis model is required for the prediction and verification of the laboratory test results.