• 한국표면공학회지
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• 제52권3호
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• pp.138-144
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• 2019

In this work, PEO (Plasma Electrolytic Oxidation) film formation behavior of Al6061 alloy was investigated as a function of applied current density of AC at 310 Hz in the range from $120mA/cm^2$ to $300mA/cm^2$ in 0.5 M $Na_2SiO_3$ solution. When applied current density is lower than a critical voltage of about $132mA/cm^2$, voltage reaches a steady-state values less than 120 V without generation of arcs and metallic color of the alloy surface remains. On the other hand, when applied current density exceeds about $132mA/cm^2$, voltage increases continuously with time and arcs are generated at more than 175 V, resulting in the formation of PEO films with grey colors. Two different types of arcs, large size and small number of arcs with orange color, and small size and large number of arcs with white color, were generated at the same time when the PEO film thickness exceeds about $50{\mu}m$, irrespective of applied current density. Formation efficiency of the PEO films was found to increase with increasing applied current density and the growth rate was obtained to be about $5{\mu}m/min$ at $300mA/cm^2$. It was also found that surface roughness of the PEO films with $70{\mu}m$ thickness is not dependent on the applied current density.

• 지역연구
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• 제8권1호
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• pp.31-50
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• 1992

The aim of this paper is to define major factors influencing land development of each of major uses (residential, commercial, industrial) in the process of rapid urban expansion. The main hypothesis of this study is that land use changing patterns are directed by supply side of land managed to public policies rather than demand side. The graphic analysis is applied to relationships between urban growth and land development process of each use and between land development project managed to public policies and land development process. Public and land development projects and zonning protection seem to be major roles of land supply and main determinants of urban spatial structure. Location factors for land development of each uses are selected in 23 variables. Factor analysis is applied to test correlation between variables in 1971 and 1981. Factor structure between two years is similar, but progressive processing of functional separation is derived such as intensive land use is grouped, different location between residential and industrial use is deep. Dependent variables are standardized to logarithm of land development of each use per unit vacant land in two periods, between 1971 and 1980 year and between 1981 year. Correlation analysis between 6 dependent variables and 23 location factors in each years are applied. Major factors of each use are selected in criteria such as high correlation with dependent variables, low correlation between independent variables and common application in two periods. As the result, major factors for residential land development are Land Readjustment Project (LRP), percent of total zoned area in residential zone, residential floor space density per available area, percent of total area in industrial use; for commercial development is distance to CBD, percent of total area in commercial use, residential floor space density per available area in each year, and volumn rate of industrial use; for industrial use is percent of total area of industrial use is percent of total area of industrial use, Industrial Estate Project (IES), LRP, and distance from CBD. Land development pattern of each use between two periods are slightly different. So 6 equation is derived from appling backward method of regession. Adjusted multiple R squares of all is more than 0.5 and those equation is statistically significant and valuable to assist urban land use forecasting.

• 한국콘텐츠학회논문지
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• 제21권2호
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• pp.248-261
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• 2021

본 연구의 목적은 성인 여성의 혈액 영양소 지표가 우울 지표에 미치는 영향을 파악하는 데 있다. 77명의 폐경기 전 여성(평균연령 44.2±6.5세)을 모집하였으며, 결측치를 제외하고 53명의 혈액지표가 우울 지표(Beck Depression Inventory)에 미치는 영향을 통계로 확인하였다. 연구대상자들의 Beck 평균은 7.6±7.2로 대부분 우울 증상은 정상치 범위였다. 다만 약간 우울 2명과 매우 심각한 우울이 2명이었다. 본 연구에서 요인분석을 한 결과 21개 문항의 Beck 우울 지표는 5개의 하위요인으로 분류되었다. 이중 신체적 우울 2개, 기분 우울 1개, 인지적 우울 1개, 미정 1개 등으로 나타났다. 상관분석 결과 중성지방, LDL(low density lipoprotein) 콜레스테롤, 칼륨이 우울 요인들과 통계적으로 유의한 정의 관계를 보인 반면, HDL(high density lipoprotein) 콜레스테롤과 나트륨, 염화이온은 우울 요인들과 부(-)의 관계를 보였다. 중성지방, 콜레스테롤, 혈당, 케톤체를 원인변수로 설정한 후 우울에 대한 영향을 다중 회귀분석을 하였을 때, HDL(high density lipoprotein) 콜레스테롤은 우울 3 요인에 통계적으로 유의한 부(-)의 영향을 미치고 있었다. 미네랄 성분만으로 우울 하위요인에 다중회귀 분석을 하였을 때, 칼륨이 정(+)의 영향을, 염화이온은 부(-)의 영향을 우울 3 요인에 영향을 미치고 있었다. 본 연구에 의하면 폐경기 전 여성의 경우 혈액 지표들 중 칼로리와 관련된 영양소와 미네랄 등은 신체적 우울 지표에 영향을 미치고 있었다. 본 연구는 혈액 지표의 우울에 대한 영향을 실증적으로 분석하였다는 의미를 갖는다. 특히 칼륨과 염화이온의 우울에 대한 영향을 수치적으로 보고한 첫 연구이다. 본 연구는 53명의 폐경기 전 여성을 대상으로 하였다는 한계를 갖는다. 향후 폐경기 이후 여성과의 비교연구, 남성과의 비교연구, 우울 환자, 기타 신경 질환자들과의 비교 연구 등이 가능할 것이다.

• 한국지반공학회논문집
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• 제33권1호
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• pp.79-91
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• 2017

반복단순전단시험기를 이용하여 해양실트질 모래의 상대밀도 변화에 따른 비배수전단파괴 거동에 대해 평균전단응력과 반복전단응력이 미치는 영향을 평가하였다. 시험결과 반복전단 변형모드는 상대밀도가 달라지더라도 유사한 양상을 보였으며, 평균전단응력과 반복전단응력으로부터 큰 영향을 받았다. 파괴에 필요한 반복하중 횟수는 반복전단응력비, 상대밀도, 그리고 평균전단응력비의 순서로 좌우되는 것으로 나타났다. 본 논문에서는 조밀한 지반과 느슨한 지반에서 상대밀도 변화에 따른 응력기반 파괴경로의 변화를 2차원과 3차원으로 제시하였으며, 3차원 파괴선도는 조밀한 지반 조건에 대해서만 한정된 한계점을 보완하여 지반의 상대밀도에 따라 반복전단응력비, 평균전단응력비, 반복하중 횟수 등의 설계 조건을 결정 할 수 있는 아주 유용한 설계도구로 활용 가능하다.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2009년도 춘계학술대회 논문집
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• pp.286-286
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• 2009

A small PEM fuel cell has two different stack configurations such as active and passive stacks. The active stack has a distintion of high power density although it makes system complex by using alr blower and related BOPs resulting in large system volume. On the contrary, passive stack has an advantage of compact system because it doesn't need air supplying devices although it reveals relatively low stack power density. In this study we fabricated two 10W PEMFC stacks with different stack configurations, active and passive stacks, and tested their performance and stability. The active stack consists of 13cells with an active area of $5cm^2$. The passive stack has 12cells with an active area of $16cm^2$. When we compared the stack performance of those stacks, the active stack showed higher power density compared to the passive stack, particularly at high voltage regions. However, at low voltage and high current regions, the passive stack performance was comparable to the active stack. The stack stability was largely dependent on the fuel humidity, particularly for active stack. At low humidity conditions, the active stack performance was decreased continuously and the cell voltage distribution was not uniform showing seriously low cell voltage at center cells mainly due to the cell drying. The passive stack showed relatively stable behavior at low humidity and the stack performance was largely dependent on the atmospheric conditions.

• Child Health Nursing Research
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• 제7권2호
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• pp.213-224
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• 2001

This study was conducted to identify the effect on the weight control of the REBT group program as a nursing intervention. For this purpose, non-equivalent control group design with pretest and posttest and follow-up test as quasi-experiment was used. Subjects of the study were consisted of twenty-four obese girls (Experimental group: 10, control group: 14) who appeared to having above 20％ of the body mass index from ane high school in M city. The whole program was carried out from January to June, 2000. Used dependent variables for evaluating the effect of the REBT group program including were weight control belief(rational thinking, emotion about exercise, eating self-efficacy, eating behavior), body mass index and serum lipids(total cholesterol, triglyceride, low-density lipoprotein, high-density lipoprotein). For evaluating the effect of the program, dependent variables was analyzed by experimental stages three times; the first week, the fourth week, and the eighth week since the experimental input began. Data were analyzed by the SAS PC＋ program with t-test, repeated measure ANOVA to determine the effect of program. The results of this study can be summarized as follows; 1. After the REBT group program, only eating self-efficacy among the weight control belief of experimental group was significantly increased than that of control group. 2. After the REBT group program, body mass index of experiment group was significantly decreased than that of control group. 3. After the REBT group program, triglyceride and low density lipoprotein among the serum lipids in the experiment group were significantly decreased than those of control group.

• Nutrition Research and Practice
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• 제6권3호
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• pp.195-200
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• 2012

The purpose of this study was to investigate the effects of ${\alpha}$-lipoic acid on body weight and lipid profiles in Sprague-Dawley rats fed a high fat diet (HFD). After 4 weeks of feeding, rats on the HFD were divided into three groups by randomized block design; the first group received the high-fat-diet (n = 10), and the second group received the HFD administered with 0.25% ${\alpha}$-lipoic acid (0.25LA), and the third group received the high-fat diet with 0.5% ${\alpha}$-lipoic acid (0.5LA). The high fat diet with ${\alpha}$-lipoic acid supplemented groups had significantly inhibited body weight gain, compared to that in the HFD group (P < 0.05). Organ weights of rats were also significantly reduced in liver, kidney, spleen, and visible fat tissues in rats supplemented with ${\alpha}$-lipoic acid (P < 0.05). Significant differences in plasma lipid profiles, such as total lipids, total cholesterol, triglycerides, low-density lipoprotein, and high-density lipoprotein, were observed between the HFD and 0.5LA groups. The atherogenic index and the plasma high density lipoprotein-cholesterol/total cholesterol ratio improved significantly with ${\alpha}$-lipoic acid supplementation in a dose-dependent manner (P < 0.05). Total hepatic cholesterol and total lipid concentration decreased significantly in high fat fed rats supplemented with ${\alpha}$-lipoic acid in a dose-dependent manner (P < 0.05), whereas liver triglyceride content was not affected. In conclusion, ${\alpha}$-lipoic acid supplementation had a positive effect on weight gain and plasma and liver lipid profiles in rats.

• 공업화학
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• 제10권3호
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• pp.456-460
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• 1999

Stockmayer 분자 모델을 도입하여 선형분자인 CO분자를 쌍극자 분자로 단순화하여 CO 기체의 YHB 동경분포함수 (radial distribution function)를 컴퓨터로 계산하였다. 얻어진 CO 분자의 YHB 동경분포함수의 신뢰도는 여러 온도에서의 밀도 변화에 따른 CO 기체의 압력을 계산하여 조사하였다. 계산된 압력들은 문헌에 알려진 CO기체의 압력과 잘 일치하였으며 계산에 사용된 온도는 273, 298, 373 K, 그리고 조사한 밀도의 범위는 최대 약 $0.013/{\AA}^3$ (최대 압력 = 1000 atm)까지이다. 계산된 압력들이 문헌에 나타난 실험치와 잘 일치하는 것으로 나타났으므로 구해진 YHB 동정분포함수는 CO 분자의 압력과 같은 밀도변화에 민감한 각종 물리 화학적 평형 양들을 신뢰성있게 계산 및 예측할 수 있을 것으로 기대된다. 또한 이 연구에서 CO 기체의 dipole-dipole 상호작용은 약 2.5 분자직경까지 효과적으로 작용하는 것으로 나타났다.

• 공업화학
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• 제9권4호
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• pp.561-564
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• 1998

Stockmayer 분자 모델을 도입하여 linear spheroidal 형태의 $C_2H_4$ 기체분자를 사중극자 (quadrupole)분자로 단순화하여 $C_2H_4$ 기체의 동경분포함수 (radial distribution function)를 계산하였다. 또한 이렇게 얻어진 동경분포함수의 신뢰도를 조사하기 위해 여러 온도에서의 밀도 변화에 따른 $C_2H_4$ 기체의 압력을 계산하여 문헌에 알려진 실험치와 비교하였다. 계산에 사용된 온도는 50,100, 그리고 $150^{\circ}C$ 이었으며 조사된 밀도의 범위에 최대 약 $0.02/{\AA}^3$ (최대 압력 = 1500 atm)까지이다. 동경분포함수는 Baker와 Henderson의 섭동이론을 응용하여 Yoon, Hacura, 그리고 Baglin (YHB)에 의해 얻어진 동경분포함수의 형식을 사용하여 컴퓨터로 계산 하였으며 계산 결과는 최대 ${\pm}5%$의 오차범위내에서 실험치와 일치하였다. 이는 YHB 동경분포함수를 사용하여 압력과 같은 밀도변화에 민감한 각종 물리량을 충분히 정확하게 예측할 수 있다는 것을 나타낸다.

• 대한한의학회지
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• 제20권1호
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• pp.151-160
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• 1999

Nitric oxide(NO) is synthesized via the oxidation of L-arginine by a family of nitric oxide synthases(NOS), which are either constitutive(cNOS) or inducible(iNOS). The induction of iNOS in tissues can lead to the sustained production of high concentrations of NO which may exert pro-inflammatory effects including vasodilation. edema, cyototoxicity, and its activity can be mediated by various pro-inflammatory cytokine, including interferon ${\gamma}(INF-{\gamma})$. tumor necrosis factor, IL- 1 and IL-6. The enzyme, iNOS, became a new target for pharmacologcal research with the aim to find new substances for the treatment of chronic inflammatory disorders. Murine macrophages produce large amounts of NO when activated with $TFN-{\gamma}$ plus LPS. The murine macrophage-like cell line, RAW 264.7, is a suitable cell model on which to perform vitro studies regarding the iNOS system. Semen jugrandis is a fatty walnut seed found in Korea. The walnut have been used in foik medicine to improve virility, to relieved asthma, and to relieve constipation. Sesquiterpenelactones were isolated from this plant. In the course of screening for NO inhibitory activity from medicnial plants, the aqueous extract of this plant was found to have a significant activity. The result are summarized as followings. 1. The viability of cells incubated in the presence of semen jugrandis increased mare than non incubated cells. 2. Semen jugrandis suppressed the production of NO in tissues dependent on density. 3. Semen jugrandis suppressed the induction of iNOS in tissues dependent on density can lead to reduced production of NO. 4. Semen jugrandis suppressed the production of superoxide in tissue depend on density. According to the above mentioned results, semen jugrandis could be applied production of NO and superoxide can lead to reduction of chronic inflammatary. And as a depence matter come into a virus of microbe and tumor cells.