• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1994년도 추계학술대회 논문집
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• pp.918-923
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• 1994

For the improvement of productivity, the reduction of cost and time for manufacturing is mandatory, especially in the field of electronic industry. The study is concemed with a practical means of systematic assistance to formability estimation and selection of reliable design specification for electronic sheet metal parts. The objective of this research work is to develop a simulation system which helps to analyze the target processes with the finite element method and to acquire available design data quickly and exactly and exactly. The simulation system developed in the study consists of design verification, selection of optimal combination of parameters, knowledge acquisition and graphical user interface(GUI). Design verification is automatically carried out by using the finite element method. A data base management system and nomograms are utilized for knowledge acquistion. The developed system has been applied to some major sheet metal forming operations such as flanging, embossing, bending and blanking. According to the simulated results, the validation of the target processes has been confirmed. Analysis data, estimation rules of formability and graphical representation of the analysis have been employed for the designer's understanfing and evaluation, thus providing a practical means of robot design and evaluation of formability for production electronic sheet metal parts.

• 대한기계학회논문집A
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• 제32권4호
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• pp.354-361
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• 2008

Cold rolled steel sheet for automotive was treated by Ar/$O_2$ atmospheric pressure plasma to improve the adhesive bonding strength. Through the contact angle test and calculation of surface free energy for cold rolled steel sheet, the changes of surface properties were investigated before and after plasma treatment. The contact angle was decreased and surface free energy was increased after plasma treatment. And the change of surface roughness and morphology were observed by AFM(Atomic Force Microscope). The surface roughness of steel sheet was slightly changed. Based on Taguchi method, single lap shear test was performed to investigate the effect of experimental parameter such as plasma power, treatment time and flow rate of $O_2$ gas. Results shows that the bonding strength of steel sheet treated in Ar/$O_2$ atmospheric pressure plasma was improved about 20% compared with untreated sheet.

• 한국임상보건과학회지
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• 제9권2호
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• pp.1493-1501
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• 2021

Purpose: The purpose of this study is to classify the characteristics of each item of CIST evaluation and to find out the degree of recognition of the characteristics of the cognitive tool. Methods: This study was conducted for occupational therapy majors at M University located in Gyeongsangnam-do. The data collection from May to June 2021. Total of 25 copies of the data were finally analyzed, SPSS Statistics 26 was used for data analysis. Results: As a result of the study, the significance level was visual reasoning 1 test strip and the visual reasoning 1 tool. In the relationship between the correspondence 1 figure simulation sheet and the figure simulation tool for each item and statistically significant, and the correspondence 2 visual reasoning 2 sheet. Visual reasoning 2 sheet and visual reasoning tool also showed that was found to be statistically significant. The correlation for visual reasoning 1 sheet and the visual reasoning 1 tool, reasoning 2 tool and visual reasoning 1 sheet, and the visual reasoning 2 tool and the verbal reasoning sheet. Conclusion: In this study, in the CIST items that may be difficult, it is better to attach the actual tool rather than the verbal explanation of the test paper to increase the efficiency of the test and the understanding of subjects with mild cognitive impairment. It was implemented by applying the tool, and it was found that the use of the tool in the visual reasoning item showed a high correlation by item. Furthermore, based on this study, it will be possible to suggest a method to control the difficulty of each subject of the cognitive evaluation tool, and to prepare a standard for future research.

• 한국결정성장학회지
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• 제25권6호
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• pp.290-293
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• 2015

최근 사회기반시설물의 구조물 유지관리 분야의 관심이 높아짐에 따라 새로운 유지관리 공법 및 신소재에 관한 연구가 활발히 진행되어지고 있다. 그중에서도 유지관리의 주요 대상인 교량 유지관리에는 탄소섬유를 이용한 공법이 주목을 받고 있다. 탄소섬유시트(Carbon Fiber Sheet, 이하 CFS)는 이미 여러 연구자들이 국내에서도 재료시험 및 보강공법에 관한 연구를 진행하여 연구결과가 보고되고 있지만, 탄소섬유 스트랜드 시트(Carbon Fiber Strand Sheet, 이하 CFSS)는 최근 새롭게 개발된 재료로써 아직까지 국내에는 연구 성과가 없는 실정이다. 따라서, 본 연구에서는 CFSS를 RC 상판 공시체에 접착보강하여 내피로성을 평가하였다. 그 결과, 무보강 RC 상판 공시체에 비해 약 25.3배의 보강 효과가 확인되었고, CFS 접착보강 RC 상판 공시체에 비교하여 약 1.2배의 보강 효과가 확인되었다.

• 한국멀티미디어학회논문지
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• 제10권7호
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• pp.912-922
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• 2007

원격교육 시스템의 평가 시스템에서 평가의 공정성을 위하여 매 평가 시 평가지의 난이도를 일정하게 유지할 수 있는 방법이 요구된다. 본 논문에서는 유전자 알고리즘 기반의 평가지 생성 알고리즘을 제안한다. 평가지의 각 문항에 대한 난이도가 제출자에 의해서 지정되는 기존의 방법과는 달리 제안한 알고리즘에서는 각 문항의 난이도가 학생들의 평가 결과에 따라 적응적으로 조절되고, 평가지의 평균 난이도를 일정한 수준으로 유지할 수 있다. 제안한 알고리즘에서는 평가지에 동일한 문항이 중복으로 포함되는 것을 배제하고, 이전 평가의 결과를 반영하여 적응적으로 난이도가 조절될 수 있는 새로운 형태의 유전 연산자를 설계하고 구현한다. 그리고 모의실험을 통해 기존의 임의선택 방법과 모의 담금질 방법에 비해 균일한 난이도를 갖는 평가지가 생성될 수 있음을 보인다.

• 공학교육연구
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• 제14권6호
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• pp.24-30
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• 2011

The purposes of this study are to describe the case of student generation questioning strategy on engineering education and to find advantages of applying this strategy and any suggestions of this strategy for the improvement. First of all, Questioning Sheet, the methods of applying the sheet and evaluation were developed, And then instructional model for using this strategy was designed which is with this sheet students are encouraged to ask questions at the beginning and the end of class. K class is for the sophomore of Dept. of Materials Science and Engineering in K University. 40 students were visited. Among them 8 was female student and 32 was male students. Only 20 students were used the questioning sheet and asked the questions. The rest of students did not use the questioning sheet. And high achievement students were more asked questions than low achievement students. At the end of the semester, the attitude and the satisfaction of the class were investigated. Achievements of students were measured also. Students of generating questions are more achieved and more satisfied. Students who generated questions have more positive attitude for the study.

• 한국자동차공학회논문집
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• 제13권5호
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• pp.42-49
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• 2005

In general, multi-lap spot weld joints are frequently present in automobile. Most research, however, has been focused on the single-lap spot weld joints until now. In this paper, tensile-shear strength tests are performed to examine the weldability of 3-lap spot joint welded by using the high strength steel sheet and the zinc coated steel sheet. The indentation depth and nugget diameter are used to propose the optimum welding conditions. The weldability is affected by the welding current and welding time for 3-lap spot joint. Meanwhile the expulsions is round to decrease with the increase of electrode force. The optimum welding conditions are presented for 3-lap spot joints of high strength steel sheet and zinc coated steel sheet.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2008년도 춘계학술대회 논문집
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• pp.507-511
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• 2008

LTCC (Low Temperature Co-fired Ceramic) has been successfully applied to ceramic substrates for circuits and micro-fluidic systems and has proven its superior performance in a variety of applications. The prediction of shrinkage in LTCC process is an important for dimensional control of micro LTCC products which has influences on electronic characteristics. For avoiding the unpredictable shrinkage of LTCC during the sintering which makes accurate placement of the circuit devices difficult, pre-processes such as WIP (Warm Isostatic Pressing) and lamination must be modified. The objective of the present investigation is to establish a proper WIP conditions for near net shape fabrication of LTCC products. This paper discusses the influence of WIP conditions on the dimensional change of LTCC sheet. In the investigation, it is shown that the shrinkage values of sheets depend on WIP conditions and sheet directions. This work is a quantitative evaluation of the effect of WIP pressure on shrinkage of LTCC sheet. Additionally, the results show anisotropic shrinkage behaviour of sheet during LTCC process.

• 한국표면공학회지
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• 제46권5호
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• pp.229-233
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• 2013

The small punch(SP) tests that can be applied to high strength sheet steel in automobile were carried out to evaluate the behavior of hydrogen embrittlement of DP sheet steels. In order to charge hydrogen at DP sheet steels, DP sheet steels were treated by the electrochemical hydrogen charging method under the charging conditions of current densities of 100, 150 and 200 $mA/cm^2$ for charging times of 5, 10, 25 and 50 hrs. Respectively, After hydrogen charging with experimental conditions, SP tests were performed. From the SP results, the correlations between the variation of bulb diameters and bulb heights with the hydrogen charging conditions were analysed. It was shown that the variation of bulb diameters were not significant with the hydrogen embrittlement due to the amounts of hydrogen charging. On the other hand, the bulb heights were observed to decrease with increasing hydrogen contents. It was thought that these results of the variation of bulb shapes after SP tests would be estimated as the index of evaluation of hydrogen embrittlement.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1995년도 추계학술대회 논문집
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• pp.642-945
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• 1995

The problem of autobody corrosion has been addressed over the past decade by the increasing use of zinc and zinc alloy costed steels in automotive application. this paper describes the evaluation of formability, weldability and painted corrosion performance of galvalume steel sheet. This paper presents an overview of the program and some initial test results on the weldability, lifetime of the electrode tip shpae of the spot welding and corrosion protection. Galvalume steel sheet improved corrosion performance and spot weldability of galvalume steel has no problem for the variation of welding current. And tip lifetime was changed according to the influence of shape.