• Journal of Mechanical Science and Technology
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• 제19권4호
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• pp.1018-1026
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• 2005

The proton exchange membrane (PEM) fuel cell system consisting of stack and balance of plant (BOP) was modeled in a MATLAB/Simulink environment. High-pressure operating (compressor type) and low-pressure operating (air blower type) fuel cell systems were con­sidered. The effects of two main operating parameters (humidity and the pressure of the supplied gas) on the power distribution characteristics of BOP and the net system efficiency of the two systems mentioned above were compared and discussed. The simulation determines an optimum condition regarding parameters such as the cathode air pressure and the relative humidity for maximum net system efficiency for the operating fuel cell systems. This study contributes to get a basic insight into the fuel cell stack and BOP component sizing. Further research using muli­object variable optimization packages and the approach developed by this study can effectively contribute to an operating strategy for the practical use of fuel cell systems for vehicles.

• 펄프종이기술
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• 제39권4호
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• pp.14-20
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• 2007

The effects of blending starches with different gelatinization temperatures on the development of ply-bond strength were systematically investigated using a three component mixture design technique. Oxidized corn starches with different gelatinization temperatures were blended with natural corn starch and sprayed for plybonding. Optimum blend ratio for maximizing plybond strength improvement for the starch blends was 40% of natural starch, 27% of oxidized starch with low gelatinization temperature and 33% of oxidized starch with high gelatinization temperature. Starch granules with the lowest gelatinization temperature gelatinizes at the lowest temperature, while the natural corn starch gelatinizes at later stage of drying. The improvement of plybond strength with starch blends were verified on machine trial as well. Plybond strength improvement obtained from the machine trial was lower than that achievable with handsheets, which was attributed to the lower internal bond strength of the linerboards made from recycled fibers.

• 대한치과기공학회지
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• 제27권1호
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• pp.19-25
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• 2005

Ti6Al4V alloy have been mainly used as implant materials. Ti-6Al-4V alloy instead of pure Ti is being widely used as biomaterials has some characteristics such as high fatigue strength, tensile strength. But it has been reported recently that vanadium component expresses cytotoxicity and carcinogenicity and aluminium component is related with dementia of Alzheimer type. In order to overcome their detrimental effects, $\beta$-phase stabilizer Nb was chosen in the present study, in addition Ta and Hf were added to Ti-40wt.%Nb alloy to improve its mechanical properties. This paper was described the influence of heat treatment of Ti-40Nb alloys with 2wt%Ta, 2wt%Hf on the mechanical properties. Specimens of Ti alloys were melted in vacuum arc furnace and homogenized at 1050$^{\circ}C$ for 24 hr. and then were aged after solution heat treat at $\alpha+\beta$ and $\beta$ regions. The mechanical properties of Ti alloys were analysed by hardness test, tensile test, elongation test and SEM test. The results can be summarized as follows: 1. The mechanical properties Ti-40wt.%Nb were improved when 2wt.% Ta and 2wt.%Hf were added. 2. The higher tensile strength value and elongation at solution heat treat was higher than solution heat treat and then were aged.

• 가정과삶의질연구
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• 제30권3호
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• pp.1-11
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• 2012

The purpose of this study is to analyze the effects of attitudes toward reasons for which abortion is permitted on needs for abortion prevention policies among 232 unmarried female students at the middle schools, high schools, and universities located in Seoul. The respondents were requested to complete the self-administered questionnaire, and the principal component analysis, t-tests, Pearson's correlations, and hierarchical multiple regression analyses were performed for analyzing data. The major findings of this study were as follows: First, the principal component analysis identified three reasons for which abortion is permitted. These are reasons under the maternal & child health law, socioeconomic reasons, and normatively unqualified reasons. Second, the female students showed permissive attitudes toward reasons for abortion under the maternal & child health law, disapproval attitudes toward socioeconomic reasons for abortion, and neutral attitudes toward abortion by normatively unqualified reasons. Students also showed high levels of needs for abortion prevention policies. Finally, hierarchical regression analyses revealed that female students' attitudes toward reasons for which abortion is permitted significantly predicted levels of needs for abortion prevention policies, after controlling their sciodemographic characteristics. The implications of the study results are discussed.

• 재활간호학회지
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• 제17권1호
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• pp.38-47
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• 2014

Purpose: This study was performed to investigate the effects of Tai Chi exercise on physical fitness and quality of life (QOL) in elderly women. Methods: This study was designed as a quasi-experimental, nonequivalent control group pre-post test design. The subjects were elderly women over 60 years old who enrolled senior citizen centers and elderly welfare center. Thirty-three people were conveniently assigned to an experimental group (n=15) or a control group (n=18). The data were collected from September 2009 to May 2010. The experimental group was trained Tai Chi exercise for 8 weeks (one hour Tai Chi classes twice a week and once a week by themselves at home). Data were analyzed by Fisher's exact test, ${\chi}^2$-test and independent t-test. Results: The experimental group experienced significant improvements in flexibility. The experimental group experienced significant improvements in physical component summary (p=.017) and mental component summary (p=.027) of QOL. Conclusion: Tai Chi exercise can be used as a nursing intervention for improvement of physical fitness and QOL in elderly women.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2000년도 ITC-CSCC -1
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• pp.441-445
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• 2000

This study is to segment white matter, gray matter, and cerebrospinal fluid(CSF) on a brain MR image of coronal section and to calculate the volume of each. First, we segmented the whole region of a brain from a black colored background, a skull and a fat layer. Then, we calculated the partial volume of each component, which was present in scanning finite thickness, with the arithmetical analysis of gray value from the internal region of a brain showing the blurring effects on the basis of the MR image forming principle. Calculated partial volumes of white matter, gray matter and CSF were used to determine the threshold for the segmentation of each component on a brain MR image showing the blurring effects. Finally, the volumes of segmented white matter, gray matter, and CSF were calculated. The result of this study can be used as the objective diagnostic method to determine the degree of brain atrophy of patients who have neurodegenertive diseases such as Alzheimer’s disease and cerebral palsy.

• 한국전자파학회논문지
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• 제12권4호
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• pp.600-610
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• 2001

본 논문에서는 초고속 위성통신 시스템의 채널 특성에 대한 성능 분석을 하였다. 고속 데이터 전송의 열화요인으로 작용하는 군지연과 비선형 분석을 통하여 다양한 전송 서비스를 제공하는 Ka 대역의 초고속 전송 시스템의 채널 성능 영향을 고찰하였다. 전송 데이터가 증가할수록 군지연과 비선형에 의한 영향은 증가하며, 군지연 선형 성분과 비선형의 AM-AM 성분이 시스템 성능 열화에 지배적으로 작용하는 것을 알 수 있었다. 고속 데이터에 따른 광대역 전송 대역폭으로 낮은 군지연과 이득 평탄도를 얻기가 어려우므로 주요 열화 요소를 등화하여 수십 Mbps에서부터 수백 Mbps 의 넓은 범위의 서비스를 동일 시스템에서 효과적으로 제공하여야 한다. 분석된 결과는 최적의 동작점을 갖는 초고속 위성통신 시스템을 설계하고 운용하는데 활용될 수 있다.

• 약학회지
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• 제51권6호
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• pp.476-481
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• 2007

A polymorphic fungus, Candida albicans, causes various forms of infections such as disseminated candidiasis and vaginitis. Recent reports indicate that the fungus is a main etiological agent for the arthritis. In search of new sources for treatment of the fungal arthritis, we examined $18{\beta}$-glycyrrhetinic acid ($18{\beta}$-GA) against C. albicans-caused septic arthritis. The compound is isolated from Glycyrrhizae Radix that is known to have various immunomodulating activities and is one of the most popular herbal medicines. For induction of animal model of a septic arthritis, mice were given an emulsion form of C. albicans cell wall mixed with Complete Freund's Adjuvant (CFA) via footpad-injection. To determine prophylactic and therapeutic effects, the component was given to the animals before or after the induction of the arthritis, respectively. Data showed that intraperitoneal administration of $18{\beta}$-GA resulted in reduction of the inflammation, indicating the component had both prophylactic and therapeutic activities. For investigation of mechanism of the $18{\beta}$-GA, inhibitory effects on NO (nitiric oxide) and on T-lymphocyte proliferation were determined. Results demonstrated that $18{\beta}$-GA suppressed NO production from LPS (lipopolysaccharide)-treated macrophages and also inhibited proliferation of Con A (concanavalin A)activated T-cells. Taken together, $18{\beta}$-GA, a pentacyclic triterpene, has anti-arthritic activity against C. albicans-caused septic arthritis, possibly by blocking NO production and T-cell suppression.

• 약학회지
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• 제35권5호
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• pp.416-426
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• 1991

The effects of an irreversible or a reversible $\alpha_1$-adrenoceptor antagonist (dibenamine or prazosin) on $\alpha_1$-adrenoceptor-mediated vasoconstrictions were studied in the endothelium-denuded rat aorta. In these experiments, the mobilization of intracelluier calcium and translocation of extracellular calcium were also studied. To exclude the modulation of endothelium releasing EDRF and EDCF, the endothelium was removed in all rat aortas. Contraction induced by phenylephrine (a full $\alpha_1$-adrenoceptor agonist) was separated into a fast phasic component of the response due to the release of intracellular calcium and a slow tonic one due to the influx of extracellular calcium. Pretreatments with increasing doses of reversible $\alpha_1$-adrenoceptor antagonist prazosin, as well as irreversible $\alpha_1$-adrenoceptor antagonist dibenamine, inhibited the phasic component of phenylephrine-induced contraction more effectively than the tonic one. Pretreatment of dibenamine (0.2 $\mu{M}$) or prazosin (10 nM) to the rat aorta abolished phasic response but remained tonic one about 41% and 51%, respectively. These results suggest that as the efficiency of phenylephrine was progressively reduced by pretreatments with increasing doses of an irreversible or a reversible $\alpha_1$-adrenoceptor antagonist (dibenamine or prazosin), the contraction induced by phenylephrine became progressively more dependent on the influx of extracellular calcium.

• 한국컴퓨터정보학회논문지
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• 제13권2호
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• pp.127-134
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• 2008

최근 들어 인터넷 사용자가 주체가 되어 생산하고 공유하는 UCC(User Created Contents)의 발달로 컨텐츠 제작 분야에서의 가장 중요한 이슈는 동영상을 쉽고 편리하게 편집하고 재생하는 시스템의 개발이다. 본 논문에서는 이러한 문제점을 해결하기 위하여 마이크로소프트사에서 COM Component로 지원하고 있는 Direct X에 포함된 동영상 편집 기술인 Direct Show를 이용하여 UCC제작 시스템을 구현하였다. 본 연구에서 새롭게 제안한 시스템은 Direct Show 기반의 변환필터 삽입 방식으로 사용자가 각종의 영상효과를 손쉽고 편리하게 UCC에 삽입할 수 있음은 물론, 기존의 프레임 단위 방식과는 달리 동영상 재생중에 각종의 영상효과를 삽입할 수 있다는 특징을 갖고 있다. 실험을 통하여 본 연구에서 개발한 필터를 사용하여 동영상의 재생과정에서 각종의 영상효과를 삽입할 수 있음을 확인하였다. 본 논문에서 제안한 시스템은 UCC 및 광고영상 제작 등에 널리 응용될 수 있을 것으로 판단된다.