가열 스테인레스 강 표면의 조성

이경철,함경희,안운선 성균관대학교 1991 論文集 Vol.42 No.1

스테인레스 강 304를 공기와 질소 기체속에서 200-500℃ 온도 범위로 가열 산화시킨 다음에 표면 산화층이 depth composition profile을 XPS로 구하였다. 기체/산화물 계면 부근에서는 주로 철이 나타나고 내부로 들어가면서 크롬의 농도가 증가한다. 그리고 크롬이 산화 상태를 나타내는 영역에서 철은 금속 상태를 나타내기 시작한다. 이런 현상은 표면쪽으로의 철 이온의 확산 속도와 용액속으로 용해속도가 다른 산화종의 확산 속도보다 빠르기 때문이라고 생각된다. 질소 기체 분위기 속에서 200℃로 가열한 시편은 공기중에서 열 처리한 것과 거의 비슷한 depth profile을 나타내었다. 그리고 이 온도에서는 공기중에서나 질소중에서 산화가 일어나지 않는다. The stainless steel 304 is oxidized at various temperatures between 200 through 500℃ temperature region both in the air and nitrogen atmosphere and analyzed them for the depth composition profile of surface region using X-ray photoelectron spectroscopy(XPS). It is found that Fe is concentrated in the gas/oxide interface, and Cr is found rich in the subsurface under the Fe rich layer. Fe begins to show a metallic state at the region where Cr is still in the oxidized state. These findings can be attributed to the greater diffusion rate of Fe ion compared to other oxidized species. The depth profile of the sample heated up to 200℃ in the nitrogen atmosphere gives a similar result with the one obtained from the sample heated in the air. It is found that no oxidation takes place at these low temperature region either in the air or in the nitrogen atmospheres.

보육교사의 교육신념과 교사 효능감에 관한 연구

이희자,함은숙,김경의 한국영유아보육학회 2003 한국영유아보육학 Vol.0 No.32

The purpose of this study is to compare overall educational belief and teachers' sense of self-efficacy of day-care teachers. The subjects of this study were 142 day-care teachers in the Cheon-Buk areas. The data were collected using questionnaires and analyzed by the statistical methods of frequencies, percentages, a Chi-Square test with SPSS program. The results of the study are as follows : 1. As the result of the investigation that what is the educational belief of the teacher according to the academic background, the personal history, and the type of day care-centers, it showed that statistically there was no significant difference. 2. Regarding the day-care teachers' sense of self-efficacy, according to the academic background was no significant difference. The teachers having 1 to 2 years of teaching experience showed the highest personal teaching efficacy and state- or public- run day-care centers teachers showed also high general teaching efficacy.

해리성 화학 흡착에 대한 흡착 등온식

안운선,함경희 성균관대학교 기초과학연구소 1988 論文集 Vol.39 No.2

고체 표면을 기체에 노출시켰을 때 일어나는 화학 흡착량을 노출량의 함수로 나타내는 기체 흡착 등온식을 activation complex theory에 입각해서 유도하였다. 이 유도 과정에서는 흡착질 분자가 우선 분자 상태의 precursor state로 흡착되고, 이어서 이 precursor state의 분자가 activated complex state를 거쳐서 해리 생성물로 된다고 가정하였다. Precursor의 농도가 대단히 낮을때는 이 흡착 등온식이 Langmuir 흡착등온식과 비슷한 꼴로 된다는 것을 알게 되었다. 이 흡착 등온식은 다결정 니켈 표면에서의 산소의 해리 흡착 과정에 적용시켜 본 결과, 실험 결과와 비교적 잘 맞았다. An adsorption isotherm which gives the chemisorbed amount of gas on solid absorbents as a function of the gas exposure is derived using the activated complex theory. It is assumed that the chemisorption takes place through a moleculary adsorbed precursor state and the activated complex formed from this precursor state. The isotherm derived in this work redudes to a simple one looking similar to the Langmuir isotherm if the concentration of the precursor state is very low. The isotherm is applied to Ni-O_2 dissociative adsorption system to find a reasonably good agreement with the experimental results.

흑연 표면에 흡착된 Kr의 이차원 지름 분포 함수

안운선,이순보,함경희,이광순 成均館大學校 1983 論文集 Vol.33 No.-

The radial distribution function for 2D fluid of Kr adsorbed on graphite surface is calculated using cluster integrals. The interaction energy between a Kr molecule and graphite surface is assumed as a pairwise addition of Lennard-Jones(12, 6) potentials. From this radial distribution function spreading pressure of the adsorbed layer is calculated. The results agree very well with experimental results and boundary conditions. The isosteric heat of adsorption is also calculated using 2D virial equation of state, and found to agree very well with experimental results.

Isotherm for $Ni-O_2$ Adsorption System

Kyoung-Hee Ham,Woon-Sun Ahn Korean Chemical Society 1990 Bulletin of the Korean Chemical Society Vol.11 No.3

The activation energy of dissociative adsorption of oxygen on polycrystalline nickel surface is calculated from adsorption isotherms obtained using X-ray photoelectron spectroscopy. Negative value of this activation energy (-5.9 kJ/mol) indicates that the adsorption takes place through an undissociated precursor state. An adsorption energy for this precursor state is calculated assuming the precursor state as a moleculary physisorbed state ($E_{ad}$ = -7.9 kJ/mol). Finally, an adsorption isotherm equation is derived as a function of the gas exposure, which agrees with the experimental isotherms reasonably good.

Stainless Steel Surface Oxidized in Strong Oxidizing Solution

Kyoung-Chul Lee,Kyoung-Hee Ham,Woon-Sun Ahn Korean Chemical Society 1991 Bulletin of the Korean Chemical Society Vol.12 No.5

Stainless steel 304 2B and BA are oxidized in 2.5 M $CrO_3/$ 5.0 M $H_2SO_4$ solution, and elemental composition and oxidized state of the surface region is analyzed as a function of the surface depth using X-ray photoelectron spectroscopy. It is found that Fe and Cr are preferentially oxidized and diffuse outward following the oxidation. Element Ni, the third major component of the steel is not oxidized and remains deep under the surface. It is also found that the oxidized Fe dissolves considerably into the solution thereby enriching the gas-oxide interface with Cr.

Eckol isolated from <i>Ecklonia cava</i> attenuates oxidative stress induced cell damage in lung fibroblast cells

Kang, Kyoung Ah,Lee, Kyoung Hwa,Chae, Sungwook,Zhang, Rui,Jung, Myung Sun,Lee, Youngki,Kim, So Young,Kim, Hee Sun,Joo, Hong Gu,Park, Jae Woo,Ham, Young Min,Lee, Nam Ho,Hyun, Jin Won Elsevier 2005 FEBS letters Vol.579 No.28

<P><B>Abstract</B></P><P>We have investigated the cytoprotective effect of eckol, which was isolated from <I>Ecklonia cava</I>, against oxidative stress induced cell damage in Chinese hamster lung fibroblast (V79-4) cells. Eckol was found to scavenge 1,1-diphenyl-2-picrylhydrazyl radical, hydrogen peroxide (H<SUB>2</SUB>O<SUB>2</SUB>), hydroxy radical, intracellular reactive oxygen species (ROS), and thus prevented lipid peroxidation. As a result, eckol reduced H<SUB>2</SUB>O<SUB>2</SUB> induced cell death in V79-4 cells. In addition, eckol inhibited cell damage induced by serum starvation and radiation by scavenging ROS. Eckol was found to increase the activity of catalase and its protein expression. Further, molecular mechanistic study revealed that eckol increased phosphorylation of extracellular signal-regulated kinase and activity of nuclear factor κ B. Taken together, the results suggest that eckol protects V79-4 cells against oxidative damage by enhancing the cellular antioxidant activity and modulating cellular signal pathway.</P>

Inhibition of Telomerase Activity in U937 Human Monocytic Leukemia Cells by Compound K, a Ginseng Saponin Metabolite

Kang Kyoung-Ah,Lee Kyoung-Hwa,Chae Sung-Wook,Kim Jeong-Ki,Seo Jung-Yeon,Ham Yong-Ho,Lee Kee-Ho,Kim Bum-Joon,Kim Hee-Sun,Kim Dong-Hyun,Hyun Jin Won The Korean Society for Biotechnology and Bioengine 2006 Biotechnology and Bioprocess Engineering Vol.11 No.1

Telomerase activation is detected in most cancerous cells; hence, telomerase is a highly selective target for cancer therapy, which plays an important role in the apoptotic process. We have previously reported that the ginseng saponin metabolite, Compound K (20-O-D-glucopyranosyl-20(S)-protopanaxadiol, IH901), inhibits cell proliferation by inducing apoptosis and cell cycle arrest at the $G_1$ phase. The present study investigated the regulation of telomerase activity in Compound K treated U937 cells. Compound K treatment caused a reduction in telomerase activity and down-regulated the human telomerase reverse transcriptase (hTERT) gene, resulting in the decreased expressions of its protein, and of the c-Myc and Spl proteins (transcription factors of hTERT). These results indicate that the anticancer activity of Compound K could be mediated by inhibition of the telomerase activity.

CD166 promotes the cancer stem-like properties of primary epithelial ovarian cancer cells

( Dae Kyoung Kim ),( Min Hee Ham ),( Seo Yul Lee ),( Min Joo Shin ),( Ye Eun Kim ),( Parkyong Song ),( Dong-soo Suh ),( Jae Ho Kim ) 생화학분자생물학회 2020 BMB Reports Vol.53 No.12

Cancer stem cells (CSCs) or tumor-initiating cells are thought to play critical roles in tumorigenesis, metastasis, drug resistance, and tumor recurrence. For the diagnosis and targeted therapy of CSCs, the molecular identity of biomarkers or therapeutic targets for CSCs needs to be clarified. In this study, we identified CD166 as a novel marker expressed in the sphereforming CSC population of A2780 epithelial ovarian cancer cells and primary ovarian cancer cells. The CD166+ cells isolated from A2780 cells and primary ovarian cancer cells highly expressed CSC markers, including ALDH1a1, OCT4, and SOX2, and ABC transporters, which are implicated in the drug resistance of CSCs. The CD166+ cells exhibited enhanced CSC-like properties, such as increased sphere-forming ability, cell migration and adhesion abilities, resistance to conventional anticancer drugs, and high tumorigenic potential in a xenograft mouse model. Knockdown of CD166 expression in the sphereforming ovarian CSCs abrogated their CSC-like properties. Moreover, silencing of CD166 expression in the sphere-forming CSCs suppressed the phosphorylation of focal adhesion kinase, paxillin, and SRC. These results suggest that CD166 plays a key role in the regulation of CSC-like properties and focal adhesion kinase signaling in ovarian cancer. [BMB Reports 2020; 53(12): 622-627]

해체현장의 비점오염권 관리방안 제안에 관한 연구

주경훈 ( Kyoung Hoon Chu ),김효진 ( Hyo Jin Kim ),이경희 ( Kyong Hee Lee ),함석현 ( Seok Heon Ham ),최진수 ( Jin Su Choi ),고광백 ( Kwang Baik Ko ) 한국물환경학회 ( 구 한국수질보전학회 ) 2010 공동 추계학술발표회 Vol.2010 No.-