• 전력전자학회:학술대회논문집
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• 전력전자학회 2014년도 전력전자학술대회 논문집
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• pp.427-428
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• 2014

독립형 태양광 LED가로등은 태양광 발전 전압, 배터리 충전전압, LED구동전압 등이 상이하므로 이러한 전압을 적절하게 매칭하기 위해서는 여러 가지 타입의 컨버터 회로가 이용되어야 한다. 하나의 시스템에 여러 가지 상이한 전압을 매칭하기 위해서 주로 쓰이는 방식은 벅-부스터 컨버터 회로로서 부스터 컨버터를 활용할 때 벅 컨버터만을 사용하는 부분에 비해서 효율이 저하되는 문제가 있다. 본 논문에서는 부스터 컨버터 대신 전압 더블러를 사용하여 전압을 2배로 상승시키고 벅 컨버터 회로만으로 상이한 전압을 매칭하는 방법으로 효율을 높이고자 한다. 이러한 새로운 토폴로지의 검증을 위하여 시뮬레이션을 수행하였다.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2011년도 전력전자학술대회
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• pp.134-135
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• 2011

이 연구의 목적은 백색 LED 광원의 색이라도 색온도에 따라 심리적 안전감과 명시성이 달라진다. 따라서 색온도를 조정할 수 있는 스탠드라이트 광원을 만들면 장시간 사물과 책을 볼 시 눈의 인지능력 향상과 눈의 피로를 감소시킬 수 있다. 본 연구를 통하여 3가지 색온도 백색 3000K 대역, 5000K 대역, 6600K 대역의 LED 광원을 이용하여 산술적 합성의 의하여 4000K 대역, 6000K 대역 등 다양하게 색온도를 구현하여 실제적으로 조명을 조사하여 인지능력과 눈의 피로가 감소 시킬 수 있는 색온도를 갖는 스탠드라이트 광원을 찾는데 목적을 둔다. 또한 4000K인 경우 3000K와 5000K LED 출력을 1:1 비율로 조사하면 4000K의 색온도가 나올 것으로 이론상 가능하고 2:1 비율로 조사하면 3500K의 색온도가 나올 것으로 예상되며 총 9가지의 산술적 조명을 구현한다. 스탠드라이트 광원을 자주 사용하는 고등학생을 대상으로 학습 분위기를 조성할 수 있는 9가지 백색 LED 색온도 광원 중 1개를 선택하여 가장 적합한 조명의 수요도 조사를 하고 본 연구의 색온도 산술적 합성 연구의 실험을 통하여 색온도가 조절 가능한 스탠드 라이트를 상용화 하는데 논문의 목적을 둔다.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2010년도 춘계학술대회 초록집
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• pp.183.1-183.1
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• 2010

Recently, the increased interest in environmental issues has led to extensive research for development of green energy generation systems. However, only one type of generation system may not be sufficient for stand-alone mode because it cannot cope with the irregularity of weather condition. A hybrid generation system is able to make up for the weakness of each system. In this paper, a stand-alone hybrid wind/PV system is developed that can guarantee the stable energy supply. The system is suitable for power supply under 50W, and a vertical savonius type of blade was designed and applied for the wind generation system.

• Journal of Mechanical Science and Technology
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• 제15권9호
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• pp.1319-1327
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• 2001

The results of stand and field testing of a combustion chamber for a heavy-duty 150 MW gas turbine are discussed. The model represented one of 14 identical segments of a tubular multican combustor constructed 1:1 scale. The model experiments were executed at a lower pressure than that in a real gas turbine. Combustion efficiency, pressure loss factor, pattern factor, liner wall temperature, flame radiation, fluctuating pressure and NOx emission were measured at partial and full loads for both model and on-site testing. The comparison of these items in the stand and field test results led to has the development of a method of calculation and the improvement of gas turbine combustors.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2001년도 가을 학술발표회 논문집
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• pp.475-482
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• 2001

Stadium stand could be led to significant dynamic response due to rhythmical activities of spectator. The dynamic loads induced by spectators movements are considered as static loads in design standard of many countries but these loads have dynamic characteristics. So, it is desirable to apply measured dynamic loads created by spectator activities and to analyze the dynamic behavior of stadium system. The precise investigation of the dynamic loads on stadium structures and the accurate analysis of dynamic behavior of stadium systems are demanded for effective design. As the floor mesh of stadium stand is refined, the number of nodes increase in numerical analysis. So it is difficult to analyze entire stadium structures and much more computer memory are necessary for vibration analysis of stadium system. In this study, the various dynamic loads induced by spectator movements are measured and analyzed. And new modeling method that reduce the nodal points of stadium systems are introduced. Vibration analysis of stadium system is executed to inspect the accuracy and the efficiency of proposed method in this paper.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2014년도 전력전자학술대회 논문집
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• pp.409-410
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• 2014

본 논문은 독립형 태양광 보안등에 적합한 전력변환기를 제안한다. 제안된 전력변환기는 플라이백-부스트 콤비네이션 전력변환기로 하나의 스위치로 독립형 태양광 보안등의 배터리 감압컨버터와 LED 구동용 승압 컨버터의 기능을 모두 수행한다. 또한 기존 플라이백 컨버터의 RCD 스너버 회로 대신, 출력에 직접 연결하여 누설 인덕터의 에너지를 출력으로 전달하여 손실을 줄이는 방법을 적용하였다. 제안된 회로를 검증하기 위해서 PSIM 시뮬레이터를 사용하였으며, 회로의 동작 및 구조를 설명하였다.

• 한국운동역학회지
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• 제22권2호
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• pp.253-259
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• 2012

The purpose of this study was to determine how smartphone use posture affects biomechanical variables and muscle activities. Eleven university students(age: $22.2{\pm}2.6$ yrs, height: $176.6{\pm}4.7$ cm, weight: $69.5{\pm}7.5$ kg) who have no musculoskeletal disorder were recruited as the subject according to having experience in using the smartphone for more than one year. Angular velocity, muscle activity, and thumb finger pressure were determined for each trial. For each dependent variable, a one-way analysis of variance (ANOVA) with repeated measures was performed to test if significant difference existed among different three conditions (p<.05). The result showed that rotational angular velocity of the first metacarpal were increased in DESK posture compared with STAND posture during SU phase. The average nEMG values of FDI(First dorsal interosseous) were less in SIT and DESK posture compared with STAND posture during SR phase. These indicated that smartphone postures may effect the thumb ROM(Range of motion) and muscle activity. This has led to suggestions of the need for further kinetic and EMG analyses to evaluate best assess and characterize with smartphone use.

• 한국산학기술학회논문지
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• 제11권1호
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• pp.61-66
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• 2010

본 논문은 LED감성조명장치를 개발하여 뇌파 파장과 조명의 색온도 변화에 따른 상관관계를 뇌파실험을 통해 측정하였다. 이를 위해 장치개발을 통한 열 해석과 뇌파실험의 두 부분으로 실험을 하였다. LED감성조명장치의 모듈은 메탈 PCB에 Chip LED를 배치하여 COMSOL Multiphysics로 열 해석 결과 LED와 PCB의 경계면 온도는 약 $80^{\circ}C$이며, PCB의 바닥면까지는 약 $50^{\circ}C$까지 변화함을 검증 하였으며, 결과적으로 실 제작의 근사치에 가까운 방열설계가 가능함이 확인 및 적합한 조명기구로 판정되었으며, 뇌파측정을 위해 색온도를 $2,300^{\circ}K$, $4,000^{\circ}K$, $6,000^{\circ}K$ 세가지 조건으로 피 실험자의 기본상태(휴식, 주의력, 집중력)를 측정 하였으며 그 결과 색온도가 낮을수록 편안함과 안락함을 느낀다는 것을 검증 할 수 있었다. $4,000^{\circ}K$의 조건으로 실험을 했을 때 주의력의 지수가 약간 높아짐을 볼 수 있는데 이는 $4,000^{\circ}K$가 우뇌의 기능을 활성화 시킬 수 있는 추론이 가능하며 $6,000^{\circ}K$이상에서는 일반 형광등 아래의 색온도와 유사함으로 상태가 변화되지 않았음을 알 수 있었다.

• 한국전문물리치료학회지
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• 제14권1호
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• pp.55-63
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• 2007

This study was designed to examine the relationship between clinical symptoms, self-efficacy, and performance of women with osteoarthritis. It is a survey study of 60 women who were diagnosed as osteoarthritis and given medical treatments from September, 2005 to October, 2005 in hospital 'H' located in Yongin-si. For clinical symptoms, radiographs of the subjects' knees were taken and evaluated the pathology grade by the Kellgren-Lawrence grade. Pain and stiffness was measured by the measure of WOMAC (Western Ontario and McMaster Universities Osteoarthritis Index), and functional reach test was measured in order to examine balancing abilities. Self-efficacy was measured by a tool which has revised the ASES (Arthritis Self-Efficacy Scale), and performance was measured by recording the difficulty of the WOMAC measurements themselves, and the time taken for 20 m walking, going up and down 9 stairs, and 5 sit-down and stand-up repetitions. The resulting differences in the other variables according to performance and the relationship between performance with variables are the following. First, an increase in pain in women with osteoarthritis led to decreased functional ability. Second, an increase in stiffness in women with osteoarthritis led to a decrease in functional ability. Third, a decrease in balance in women with osteoarthritis led to a decrease in functional ability. Fourth, a decrease in self-efficacy in women with osteoarthritis led to a decrease in functional ability. Fifth, the variables for estimating the performance by self-report were pain and self-efficacy. The variables for estimating the performance by recording the time taken was balance and self-efficacy. As a result factors such as pain, balance and self-efficacy in women with osteoarthritis were closely related to performance. Based on the results, it seems that physical therapy programs to decrease pain and to increase the balance in women with osteoarthritis, and psychological approaches to increasing self-efficacy are needed. I hope that the results of this study will be useful data for clinical management and intervention for women with osteoarthritis.

• 한국CDE학회지
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• 제21권2호
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• pp.61-64
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• 2015

In this paper, the FREECAD 0.14 was used for modeling conventional Selfie-stick and the newly proposed Selfie-stick design. The purpose of this paper is to demonstrate the utility of FREECAD 0.14, which is open-source and still in development for further use. After modeling the conventional Selfie-stick, CatiyaV5 was used to assemble FREECAD 0.14 drawn elements. Main issue in newly designed Selfie-stick is the portability. To improve portability of the Selfie-stick, folding mechanism was adopted from folding LED stands. Several mechanisms were adopted to improve user convenience as well. Ansys 14.0 was used for structural analyses of conventional Selfie-stick model and the newly designed model as well. Several simplifications for the models were needed to process the analyses. When analyzing the newly designed model various materials were used one by one to find compatible composition. Using Magnesium Alloy for the stick and the hand grip was found to be compatible. FREECAD was useful for suggestion of the newly designed model but not so much useful to design an actual product. Various efforts would make FreeCAD the best choice for industrial use for free as it is named.