열전도성 플라스틱을 이용한 21 W급 LED Light Engine의 방열설계

최원호,최두호,이진열,박대희,Choi, Won-Ho,Choi, Doo-Ho,Lee, Jin-Yeol,Park, Dae-Hee 한국전기전자재료학회 2015 전기전자재료학회논문지 Vol.28 No.3

This study will design the structural optimization of 21 W LED heat sink using the thermal conductive plastic materials. The thermal conductive plastic heat sink is inferior to aluminum heat sinks in thermal properties. This study will solve this problem using formability of thermal conductive plastic heat sink. A heat sink was optimized in terms of the number, and the thickness of fins and the base thickness of the heat sink, using the Heatsinkdesigner software. Also by using SolidWorks Flow simulation and thermal analysis software, the thermal characteristics of the heat sink were analyzed. As the result, the optimized heat sink has 17 fins, which are 1.5 mm thick and a 3.7 mm-thick base. The highest and the lowest temperature were $51.65^{\circ}C$ and $46.24^{\circ}C$ respectively. Based on these results, The thermal conductive plastic heat sink is considered possible to overcome heating problem when designing in complex structure.

유전 알고리즘을 이용한 회전기계의 최적 현장평형잡이

최원호,양보석,주호진,Choi, Won-Ho,Yang, Bo-Suk,Joo, Ho-Jin 대한기계학회 1996 大韓機械學會論文集A Vol.20 No.6

This paper present the claculating method of optimum correction mass within permissible vibration linits for ratating machinery in two-plane field balancing. Basic technique of this method is based on influence coefficient method, and grphic vector composition that the resultant of two influence vectors obtained by trial mass have to be equilibrium with initial vibration vector in the each correction plane. Genetic algorithm which is a search algorithm based on the mechanism of natural selection and natural genetics is sued for vector composition, and SUMT method is used to objective function which seeks optimum correction mass for balancing a rotor.

마찰교반점접합한 5454-O 알루미늄합금 판재의 접합부 거시조직 및 기계적 특성에 미치는 접합인자의 영향

최원호,권용재,윤성욱,강명수,임창용,서종덕,홍성태,박동환,이광학,Choi, Won-Ho,Kwon, Yong-Jai,Yoon, Sung-Ook,Kang, Myoung-Soo,Lim, Chang-Yong,Seo, Jong-Dock,Hong, Sung-Tae,Park, Dong-Hwan,Lee, Kwang-Hak 대한용접접합학회 2011 대한용접·접합학회지 Vol.29 No.6

Friction stir spot welding between 5454 aluminum alloy sheets with the different thicknesses of 1.4 and 1.0 mm was performed. In the welding process, the tool for welding was rotated ranging from 500 to 2500, and plunged to the depth of 1.8 mm under a constant tool plunge speed of 100 mm/min. And then, the rotating tool was maintained at the plunge depth during the dwell time ranging from 0 to 7 sec. The pull-out speed of the rotating tool was 100 mm/min. The increase of tool rotation speed resulted in the change of the macrostructure of friction-stir-spot-welded zone, especially the geometry of welding interface. The results of the tensile shear test showed that the total displacement and toughness of the welds were increased with the increase of the tool rotation speed, although the maximum tensile shear load was decreased. However, the change in the dwell time at the plunge depth of the tool did not produce the remarkable variation in the macrostructure and mechanical properties of the welds. In all cases, the average hardness in friction-stir-spot-welded zone was higher than that of the base metal zone. By the friction stir spot welding technique, the welds with the excellent mechanical properties than the mechanically-clinched joints could be obtained.

예비 과학 교사의 화학 개념에 대한 이해도와 문제 해결 능력 조사

최원호,윤혜선,Choi, Won-Ho,Yoon, Hyeo-Seon 대한화학회 2012 대한화학회지 Vol.56 No.5

본 연구에서는 사범대학 과학교육과에 재학 중인 예비 과학 교사들을 대상으로 고등학교 교육과정에 해당하는 화학 개념의 이해도와 문제 해결 능력을 관련 문항을 이용하여 조사하였다. 연구 결과, 오답을 선택하며 문제 해결에 필요한 정확한 개념을 가지지 못하는 예비 과학 교사들이 모든 문항에서 발견되었다. 이 결과의 원인을 찾기 위한 심층 질문을 통해 일부 예비 과학 교사에게서 나타난 몇 가지 사실을 확인할 수 있었다. 첫째, 예비 과학 교사들은 고등학생들에 비해 상대적으로 정확한 개념을 가지고 있었지만 몇몇 개념들에 대해서 고등학생들과 동일한 오개념을 가지고 있었다. 둘째, 과학개념의 일반적 정의나 의미는 알고 있었지만 교육과정 상 강조하는 내용을 정확히 이해하지 못하였으며, 시각적으로 인지된 정보로 문제를 해결하려는 경향이 있었다. 셋째, 문제 해결과 관련된 일반적 개념의 필요성은 인식하는 반면 탐구와 관련하여 문제 해결에 필수적인 능력을 간과하거나 문제 해결에 도움이 되지 않는 상위 교육과정의 필요성을 제안하는 경향이 있었다. We investigated pre-service science teachers' understanding of and problem-solving ability with regard to chemistry concepts in the high school curriculum. For this purpose, we used related certain items and analyzed the results. We found that in the case of all items, some pre-service science teachers, who do not have clear concepts, selected incorrect answers. The in-depth interviews we conducted with the participants revealed some of the causes for the results obtained. First, although pre-service science teachers have better concepts as compared to high school students, they have the same misconceptions as students with regard to some concepts. Second, although they are familiar with the general definitions or meanings of scientific concepts, they do not understand the specific content that is emphasized in the curriculum. Moreover, they tend to solve problems by the information visually conceived. Third, although they know the necessity of general concepts related to problem solving, they sometimes fail to apply inquiry skills and tend to suggest concepts from the higher education curriculum that are not helpful for solving problems.

국가수준 학업성취도 평가에서 중학생의 성취수준별 특징 분석: 화학 영역을 중심으로

최원호,Choi, Won-Ho 대한화학회 2013 대한화학회지 Vol.57 No.1

우리나라 중학교 3학년 학생들을 대상으로 실시한 2009, 2010년 국가수준 학업성취도 평가 결과를 이용하여 학생들의 성취수준별 특징을 조사하였다. 성취수준별 대표 문항 분석을 통하여 다음과 같은 내용을 알았다. 우수학력 학생들은 현상의 변화를 물질의 특징과 모형을 함께 이용하여 설명할 수 있고, 보통학력 학생들은 단순한 상황에 한정하여 모형을 활용하여 현상을 설명할 수 있으며, 기초학력 학생들은 모형의 의미를 이해하지 못하여 물질 현상을 모형을 이용하여 설명하지 못했다. We investigated student's characteristics in each educational achievement level using the results of the NAEA (National Assessment of Educational Achievement) in 2009 and 2010 for Grade 9 students. The analysis of representative items of each educational achievement level revealed that (a) advanced level students could explain the change in phenomena with both the characteristics of matter and the model, (b) proficient level students could explain only simple phenomena with the model, and (c) basic level students did not understand the model and were therefore unable to use it to explain phenomena.

ARM 프로세서를 이용한 직렬과 병렬 데이터 통신

최원호(Won-Ho Choi),황욱철(Wook-Chul Hwang),정민수(Min-Soo Jung) 한국정보과학회 2000 한국정보과학회 학술발표논문집 Vol.27 No.1A

ARM 프로세서는 CISC 보다는 간단하게 디자인된 RISC로서 내장 응용프로그램에 적합하기 때문에 앞으로 모든 디지털 기기에 ARM 코어를 기반으로 한 핵심 칩들이 생산된다. 그러나 명령어가 CISC 보다는 적기 때문에 주어진 작업에 대해 완전한 처리를 위해서는 보다 많은 명령어들을 필요로 한다. 이러한 ARM 프로세서에서 데이터를 전송할 때 사용하는 메모리 영역과 레지스터들을 프로그램과 함께 분석하였다.

모듈화를 위한 차체 볼팅 조립구조에 대한 고찰

최원호(Choi Won-Ho),자동화(Chang Dong-Hwa),전시현(Jeon Si-Hyun) 한국철도학회 2008 한국철도학회 학술발표대회논문집 Vol.- No.-

Recently, a rolling stock has been requiring more efficient manufacturing method than welding for the improved quality and the enhanced fabrication of car body structure. As an alternative, modularization of car body structure is being studied. Accordingly, rolling stock manufacturers need to make it possible to develop a variety of rolling stock vehicles made from modularized sub-blocks in order to meet various customer"s demands. The bolt-assembled car body structure for modularization is known to have many advantages over the existing weld-assembled method and is free from the possible welding defects, such as welds between dissimilar metals, crack, deformation and loss of strength. Consequently, we can have the improved overall quality, the reduced man powers for assembly and the satisfied strength of car body structure. The review is about the bolt-assembled car body structure for modularization to assure global competitiveness and an enhanced technique in terms of assembly methodology of car body structure.

Granular Calcite 충진 컬럼을 이용한 불산폐수 처리

최원호(Choi Won-Ho),박주양(Park Joo-Yang) 대한토목학회 2007 대한토목학회논문집 B Vol.27 No.4B

전자공장에서 발생하는 불산폐수 중의 불소를 보다 고효율로 제거하는 방법으로서 기존의 불소처리제인 lime 대신 calcite를 선별하여 그 특성을 살펴보았다. 모의 불산폐수 및 불산 실폐수를 이용한 회분식 실험 결과, calcite는 lime과 거의 동등한 불소 제거효율을 나타냄에도 불구하고 처리수 중의 잔류 칼슘농도가 lime에 비해 현저히 적고 처리수의 pH 또한 중성에 가까웠다. 이에 granular calcite를 충진한 컬럼을 이용한 연속식 실험을 수행한 결과, F? 농도 1,055.9 mg/L의 고농도 불산폐수를 배출수 허용 기준인 15 ₃/L 이하로 안정하게 처리할 수 있었으며, 유입폐수의 유속을 증가시켰을 때 처리수의 불소 농도는 7.7 ₃/L까지 저감되었다. 강산성인 불산폐수는 컬럼 통과 후 pH 7~8로 중화되었으며, 유출수의 Ca²? 농도는 67122 ㎎/L을 나타내었고, 폐수 중의 기타 무기 음이온들도 그 농도가 약간 감소하였다. 불산 실폐수에는 일칼리도를 유발하는 물질이 전혀 검출되지 않았으나 컬럼 처리수는 최고 967.1 ㎎/L(as CaCO₃) 정도의 높은 총 알칼리도를 나타내었다. This study describes a new fluoride removal process using calcite that can efficiently treat hydrofluoric acid (HF) wastewater discharged from semiconductor industries. In the batch experiments using calcite and lime to treat artificial or real HF wastewater, the residual calcium concentration of calcite was lower than that of lime, and the pH value of calcite was neutral region in contrast to lime in a high pH region, even though the fluoride removal rate of calcite was comparable to that of lime. Continuous experiment using a packed column with granular calcite was performed to observe the successive fluoride removal capacity of calcite. The real HF wastewater concentration of 1,055 ㎎/L was reduced to the level of less than 15 ㎎/L, and it was further reduced as low as 7.7 ㎎/L when flow rate was increased. The effluent pH and calcium were 7~8 and 67~122 ㎎/L. Some anions were slightly reduced. The total alkalinity of effluent reached the maximum level of 967.1 r㎎/L (as CaCO₃), which was gradually reduced and not detected after breakthrough.

화물전기기관차 차체개발

최원호(Choi won-ho),곽태호(Tea-Ho Kwak),김구식(Kim ku-sik) 한국철도학회 2011 한국철도학회 학술발표대회논문집 Vol.2011 No.10

Current freight electric locomotives (132 ton) of the eco-friendly and can carry large cargo logistics as a means of generation has increased the demand at home and abroad. Especially Freight electric locomotives to increase the traction it is easy to mass and rapid transport. In addition Freight electric locomotives is no exhaust and low noise compared to diesel –electric locomotives and it can be eco-friendly transportation. CO_CO BOGIE of Freight electric locomotives has no the center pivot and Traction_Rod and Spring of CO_CO BOGIE is mounted on the body. These freight electric locomotives to be satisfied with the safety regulations. Carbody development satisfied Implementation of optimum body and collision is the focus. Accordingly the different approach in the upper and lower carbody structure and interior and equipment placement is needed. On this paper the contents give explanation of cases on carbody design composed of freight electric locomotives now developed and process of improvement by structure analysis and collision analysis.

우리나라 과학과 교육과정의 진단과 전망

최원호(Choi, Won-Ho) 서울대학교 교육종합연구원 2013 교육연구와 실천 Vol.79 No.-

본 연구에서는 2009 개정 과학과 교육과정의 특징을 몇 가지 쟁점을 중심으로 조사하였다. 조사한 특징을 바탕으로 새 교육과정에서 고려해야할 사항을 논의하였다. 논의한 내용은 과학 소양, 과학에 대한 흥미, 탐구 수업 방안, 과학 수업에서 핵심 역량, 교과군 및 학년군 설정, 과학에서 융합 수준, 교육과정과 평가의 일관성이었다. 우리나라 과학 교육과정은 과학 소양 함양을 위해 탐구를 지속적으로 강조하고 있지만, 구체적 내용은 과학 소양 함양을 위해 적절하지 않다. 2009 개정 교육과정에서 강조하는 과학 소양에 해당하는 ‘창의적 문제 해결력’ 향상을 위해 교육과정의 구체적 내용에 대하여 좀 더 연구를 진행할 필요가 있다. This study investigated the characteristics of the 2009 revised science curriculum in view of some issues. We discussed some considerations of new science curriculum based on the characteristics of the 2009 revised science curriculum, for example scientific literacy, interest in science, inquiry lesson plan, core competencies in the science lesson, subject group and grade group setting, the level of convergence in science, consistency of curriculum and assessment. Although Korean science curriculum has emphasized inquiry for scientific literacy, concrete contents are not proper for improvement of scientific literacy. We should study more about concrete contents that could improve creative problem solving ability which was scientific literacy emphasized in 2009 revised science curriculum.