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.

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.

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.

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.

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.

신경회로망을 이용한 회전기계의 고장진단에 관한 연구

최원호 ( Won Ho Choi ),양보석 ( Bo Suk Yang ) 한국어업기술학회 1992 수산해양기술연구 Vol.28 No.2

기업의 리더십유형에 따른 직무만족과 조직성과에 미치는 관계 연구

최원호(Choi, Won-Ho) 국제관광산업학회 2016 국제관광산업연구 Vol.9 No.2

The most crucial component of every organization being human in order for the organizational objective to be attained each organizational will be dependent upon the individual’s ability. Therefore with uncertainty and complexity in radically changing modern society to meet the individual desire for change at higher level a new flexible and proactive leadership style is needed. Another crucial business for the organization would be individual attitude toward his own organization. This empirical study has made an analysis on the relationship between job satisfaction and organizational commitment of transformation and transactional leadership among the subjects at small and medium-sized rms located in Kwang-Ju and South Jeolla province. The purpose of this study is to lay out an approach on the role of a leadership for the organizational objective, the impact of leadership on the relationship between leadership styles and organizational performance. Firstly, the analysis on the relationship between leadership styles and job satisfaction has shown that, for the individuals to feel job satisfaction in his workplace, the leader should have a strong conviction with his self-assuredness, faith, and moral fairness, granting each member condence, stimulating them to achieve higher-level desire so as to have strong motivation for their loy goals. In the meanwhile, if the leaders and team players are rewarded, the higher the level of their job satisfaction and performance will become. Secondly, this also had investigated the studies on leadership styles and organizational commitment and found that the modern organization members showed lower gures in organizational commitment, moral uprightness, and aective & emotional attachment. Also it was proposed that the transactional leadership styles nd it hard to have the members committed to the organization. The arts of compromise, obedience and negotiation will be key elements for this leader. Therefore the leaders’ creative and reformative ability will have each member to have autonomy and sense of independence, leading them to develop themselves open-minded. Thirdly, a good leader should know how to work on individual characteristics, for each individual may have different impact on the performance. It was discussed that he now only has to know how to handle their vision development encouraging them to better produce rationalized and creative perspective, but to decide if they need reward intervention in-between. In summary, it is proposed that the leaders should acknowledge the importance of leadership in managing job satisfaction and organizational commitment. In other words, a leader combines the knowledge of developing vision, encouraging the team players, treating them fairly and at times dierently according to their performance. And in this study, which leadership model has stronger impact on job satisfaction and commitment in small and medium-sized rms had been discussed as well.

‘대상 a’를 향한 욕망의 상징적 실현

최원호(Won Ho Choi) 한국멀티미디어학회 2010 멀티미디어학회논문지 Vol.13 No.11

주체의 욕망과 디지털 영상에 관한 연구

최원호(Won-Ho Choi) 한국멀티미디어학회 2013 멀티미디어학회논문지 Vol.16 No.12

전력선 통신을 이용한 원격 전력분석 및 제어시스템에 관한 연구

최원호(Won-ho Choi),이후찬(Hoo-chan Lee),박종연(Chong-yeun Park) 전력전자학회 2005 전력전자학술대회 논문집 Vol.- No.-

RPA(Remort Power Analysis)and RC(Remote Control) System have been researched from former several decade for a various power rate system, a efficent power service and rising of personal expenses, etc. But the existing RPA and RC System have disadventage which are complex and high cost to install an individual communication network of electricity company. This paper proposed a new type of RPA and RC System using PLC with Internet. and made components for proposal system. so we made the PLC modem , the digital watt-hour meter with a build in PLC modem and the softwere on server computer for establishing the proposal system. The bit rate of the proposed system is about 4800bps.