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음영환,김홍정,고창섭 충북대학교 컴퓨터정보통신 연구소 2006 컴퓨터정보통신연구 Vol.14 No.1
전기강판으로 제작된 전기기기의 보다 정확한 수치적인 해석을 위해서는 회전자계(Rotating magnetic field)에 따른 전기강판의 자계특성을 정확하게 측정할 필요가 있다. 본 논문에서는 2방향 자계인가 형 SST(single sheet tester)를 이용하여 회전자계 인가에 따른 등방성 및 이방성 전기강판의 자계 특성을 측정하였다. 실험을 통하여 등방성 시료와 이방성 시료에 대하여 각각 회전자계 및 교번/회전 자계의 혼합형 자계를 인가하여 1.6[T]와 1.2[T]까지 측정할 수 있었으며, 교번자계 하에서의 철손(Alternating Iron Loss)외에 회전자계의 인가로 인한 B와 H의 위상 차이를 발생하는 회전자계 손실을 측정하였다. It is necessary to measure precisely the magnetic characteristics of electrical steel sheets under rotating magnetic fields, for the accurate numerical performance analysis of electric machines made of electrical steel sheets. In this paper, the magnetic characteristics of electrical steel sheet is measured under rotating magnetic fields using a double-excitation type single sheet tester. Through experiments, The rotating magnetic properties of a Non-oriented and Grain-oriented electrical steel sheet are measured up to 1.6[T] and 1.2[T] respectively. In addition, the iron losses due to not only the alternating magnetic fields, but also the rotating magnetic fields are measured.
Eum, Da-Young,Byun, Joo-Yun,Yoon, Chang-Hwan,Seo, Woo-Duck,Park, Ki-Hun,Lee, Jin-Hwan,Chung, Hee Young,An, Sungkwan,Suh, Yongjoon,Kim, Min-Jung,Lee, Su-Jae Lippincott Williams Wilkins, Inc. 2011 Anti-cancer drugs Vol.22 No.8
A combined treatment with conventional chemotherapies can enhance the effectiveness of chemotherapeutic agents against cancers. Here, we have shown that the naturally occurring triterpenoids synergistically enhance the response of cervical cancer cells to taxol. Of the triterpenoid compounds, pristimerin enhanced the anticancer effect of taxol with the highest efficiency by combination. Pristimerin synergizes with taxol to inhibit clonogenic survival and tumor growth in nude mice, and to enhance cell death in cervical cancer cells. A combined treatment with taxol and pristimerin induced cervical cancer cell death by increasing intracellular reactive oxygen species levels, upregulation of death receptor death receptor 5 (DR5), activation of Bax, and dissipation of mitochondrial membrane potential. Treatment with N-acetyl-L-cysteine, a thiol-containing antioxidant completely blocked combined treatment-induced Bax translocation as well as DR5 upregulation. Moreover, inhibition of Jun N-terminal kinase/c-Jun pathway attenuated cell death by blocking DR5 upregulation and Bax activation. These results indicate that the triterpenoid, pristimerin, synergistically enhances taxol response of cervical cancer cells through DR5 expression and Bax activation. Furthermore, the reactive oxygen species-dependent activation of the Jun N-terminal kinase/c-Jun pathway is required for the DR5 upregulation and Bax activation. The molecular mechanism revealed by this study may aid in the design of future combination cancer therapies against cells with intrinsically reduced sensitivity to taxol.
Genotoxicity Studies on Carrageenan : Short-term In Vitro Assays
Young-Shin Chung,Ki-Hwan Eum,Seon-A Choi,Se-Wook Oh,Sue Nie Park,Young-Na Yum,Joo-Hwan Kim,Young-Rok Seo,Michael Lee 한국독성학회 2009 Toxicological Research Vol.25 No.1
Carrageenan is a naturally-occurring sulfated polygalactan which has been widely used in the dairy industry and a gelling agent in non-dairy products. In this study, four short-term in vitro genotoxicity assays were investigated to evaluate the potential genotoxic effects of carrageenan. The mutagenicity of carrageenan was evaluated up to a maximum dose of 5 ㎎/plate in Ames test. There was no increase in the number of revertant colonies compared to its negative control at any dose in all of strains tested. To assess clastogenic effect, the in vitro chromosomal aberration assay was performed using Chinese hamster lung cells. Carrageenan was not considered to be clastogenic in this assay at up to the highest feasible concentration which could be evaluated. The in vitro comet assay and micronucleus test results obtained on L5178Y cells also revealed that carrageenan has no genotoxicity potential, although there was a marginal increase in micronuclei frequencies and DNA damage in the respective micronucleus and comet assays. Taken together, our results indicate that carrageenan was not genotoxic based on four in vitro genotoxicity results.
In Vitro Studies on the Genotoxic Effects of Wood Smoke Flavors
Young-Shin Chung,Jun-Ho Ahn,Ki-Hwan Eum,Seon-A Choi,Se-Wook Oh,Yun-Ji Kim,Sue Nie Park,Young-Na Yum,Joo-Hwan Kim,Michael Lee 한국독성학회 2008 Toxicological Research Vol.24 No.4
Smoke flavors based on the thermal decomposition of wood have been applied to a variety of food products as an alternative for traditional smoking. Despite its increasing use, the available genotoxicity data on wood smoke flavors (WSF) are still controversial. Thus, potential genotoxic effects of WSF in four short-term in vitro genotoxicity assays were investigated, which included the Ames assay, chromosomal aberration assay, micronucleus test and the alkaline comet assay. WSF did not cause any mutation in the Ames assay using five tester strains at six concentrations of 0.16, 0.31, 0.63, 1.25, 2.5 and 5 ㎕/plate. To assess clastogenic effect, the in vitro chromosomal aberration assay was performed using Chinese hamster lung cells. No statistically significant increase in the number of metaphases with structural aberrations was observed at the concentrations of 1.25, 2.5, and 5 ㎕/㎖. The in vitro comet assay and micronucleus test results obtained on L5178Y cells also revealed that WSF has no genotoxicity potential, although there was a marginal increase in micronuclei frequencies and DNA damage in the respective micronucleus and comet assays. Taken together, based on the results obtained from these four in vitro studies, it is concluded that WSF is not a mutagenic agent in bacterial cells and causes no chromosomal and DNA damage in mammalian cells in vitro.
In Vitro Studies on the Genotoxic Effects of Wood Smoke Flavors
Chung, Young-Shin,Ahn, Jun-Ho,Eum, Ki-Hwan,Choi, Seon-A,Oh, Se-Wook,Kim, Yun-Ji,Park, Sue-Nie,Yum, Young-Na,Kim, Joo-Hwan,Lee, Michael Korean Society of ToxicologyKorea Environmental Mu 2008 Toxicological Research Vol.25 No.2
Smoke flavors based on the thermal decomposition of wood have been applied to a variety of food products as an alternative for traditional smoking. Despite its increasing use, the available genotoxicity data on wood smoke flavors (WSF) are still controversial. Thus, potential genotoxic effects of WSF in four short-term in vitro genotoxicity assays were investigated, which included the Ames assay, chromosomal aberration assay, micronucleus test and the alkaline comet assay. WSF did not cause any mutation in the Ames assay using five tester strains at six concentrations of 0.16, 0.31, 0.63, 1.25, 2.5 and 5 ${\mu}l/plate$. To assess clastogenic effect, the in vitro chromosomal aberration assay was performed using Chinese hamster lung cells. No statistically significant increase in the number of metaphases with structural aberrations was observed at the concentrations of 1.25, 2.5, and 5 ${\mu}l/ml$. The in vitro comet assay and micronucleus test results obtained on L5178Y cells also revealed that WSF has no genotoxicity potential, although there was a marginal increase in micronuclei frequencies and DNA damage in the respective micronucleus and comet assays. Taken together, based on the results obtained from these four in vitro studies, it is concluded that WSF is not a mutagenic agent in bacterial cells and causes no chromosomal and DNA damage in mammalian cells in vitro.
음영환(Young Hwan Eum),고창섭(Chang Seop Koh),김홍정(Hong Jung Kim),홍선기(Sun-Ki Hong),신판석(Pan Seok Shin) 대한전기학회 2006 대한전기학회 학술대회 논문집 Vol.2006 No.4
전기강판으로 제작된 전기기기의 보다 정확한 수치적인 해석을 위해서는 회전자계(Rotating magnetic flux)에 따른 전기강판의 정확한 자계특성 측정이 필요하다. 본 논문에서는 개발된 2방향 자계인가 형Single sheet tester를 이용하여 회전자계에 따른 전기강판의 자계특성을 측정하였다. 실험을 통하여 등방성 시료와 이방성 시료에 대하여 각각 회전자계 및 교번, 회전자계의 혼합형 자계를 인가하여 1.6[T]와 1.2[T]까지 측정할 수 있었으며, 일반적인 철손(Alternating Iron Loss)외에 회전자계 인가 시에 B와 H의 위상차이에 의해 발생하는 회전자계 손실을 측정하였다.
음영환(Young Hwan Eum),함승진(Seung Jin Ham),고창섭(Chang Seop Koh) 대한전기학회 2006 대한전기학회 학술대회 논문집 Vol.2006 No.10
일반적으로 전기강의 특성측정에는 Epstein frame과 Single sheet tester를 이용한 측정법이 사용된다. 그러나 위의 방법은 시료의 규격이 매우 제한 적이며 Sheet 형태의 시료를 요구하기 때문에 측정이 용이하지 못한 경우가 많다. 이러한 경우를 위한 측정법이 Ring test 측정법으로 시료에 제한이 적기 때문에 그 활용도가 매우 높으며 특히 Bulk 형태의 시료에 대해서는 거의 유일한 측정법이라 하겠다. 본 논문에서는 0.2㎐의 교번자계 여자를 통해 Bulk형 전기강의 특성 측정을 하였으며, 정현파 자속밀도 조건과 정현파 여자 전류 조건에서의 B-H특성과 철손을 측정, 비교하였다.
Genotoxicity Studies on Carrageenan: Short-term In Vitro Assays
Chung, Young-Shin,Eum, Ki-Hwan,Choi, Seon-A,Oh, Se-Wook,Park, Sue-Nie,Yum, Young-Na,Kim, Joo-Hwan,Seo, Young-Rok,Lee, Michael Korean Society of ToxicologyKorea Environmental Mu 2009 Toxicological Research Vol.26 No.1
Carrageenan is a naturally-occurring sulfated polygalactan which has been widely used in the dairy industry and a gelling agent in non-dairy products. In this study, four short-term in vitro genotoxicity assays were investigated to evaluate the potential genotoxic effects of carrageenan. The mutagenicity of carrageenan was evaluated up to a maximum dose of 5 mg/plate in Ames test. There was no increase in the number of revertant colonies compared to its negative control at any dose in all of strains tested. To assess clastogenic effect, the in vitro chromosomal aberration assay was performed using Chinese hamster lung cells. Carrageenan was not considered to be clastogenic in this assay at up to the highest feasible concentration which could be evaluated. The in vitro comet assay and micronucleus test results obtained on L5178Y cells also revealed that carrageenan has no genotoxicity potential, although there was a marginal increase in micronuclei frequencies and DNA damage in the respective micronucleus and comet assays. Taken together, our results indicate that carrageenan was not genotoxic based on four in vitro genotoxicity results.