• 한국초전도ㆍ저온공학회논문지
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• 제16권1호
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• pp.14-18
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• 2014

The mechanical, electrical and thermal characteristics of insulating materials may significantly affect the performance and reliability of electrical devices using superconductors. General method to provide insulating layer between coated conductors is wrapping coated conductor with Kapton tape. But uniform and compact wrapping without failure or delamination in whole coverage for long length conductor is not a simple task and need careful control. Coating of insulating layer directly on coated conductor is desirable for providing compact insulating layer rather than wrapping insulating layers around conductor. Ceramic added polymer has been widely used as an insulating material for electric machine because of its good electrical insulating properties as well as excellent heat resistance and fairy good mechanical properties. The insulating layer of coated conductor should have high breakdown voltage and possesses suitable mechanical strength and maintain adhesiveness at the cryogenic temperature where it is used and withstand stress from thermal cycling. The insulating and mechanical properties of polymer can be improved by adding functional filler. In this study, insulating layer has been made by adding ceramic particles such as $SiO_2$ to a polymer resin. The size, amount and morphology of added ceramic powder was controlled and their effect on dielectric property of the final composite was measured and discussed for optimum composite fabrication.

• 대한산업공학회지
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• 제29권3호
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• pp.197-205
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• 2003

Many people get plenty of information from World Wide Web, and the study of the factors that affect on reading task on web browser is presenting important issue. But domestic studies on legibility of Korean on web environment were relatively poor and the study about suitable text layout for skimming wasn't carried out also. At this point, this study was performed to investigate the effects of two types of reading, three levels of line length, and three levels of interlinear spacing on comprehension and reading rate when subjects read the materials on web browser. Reading speed, error rate, subjective preference and SACL(Stress and Arousal Checklist) evaluation were measured to evaluate the effects. Eighteen volunteer subjects participated in eighteen web document sessions with two different reading types, three different line lengths, and three different interlinear spacings. Statistical results from objective and subjective evaluations indicate that 50 characters per line of line length and 100 percents of interlinear spacing improved reading rate, overall error rates were reduced when reading normally, and SACL measures were increased at fast reading type. Consequently, in order to design text layout to retrieve information in WWW environment effectively, just applying guidelines of traditional printed material is not proper. Therefore, it is effective to consider reading type, line length, and interlinear spacing. Implications of these results and suggestions for the further study are also addressed.

• 한국암반공학회:학술대회논문집
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• 한국암반공학회 2008년도 국제학술회의
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• pp.43-51
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• 2008

Currently an increasing number of urban tunnels with small overburden are excavated according to the principle of the New Austrian Tunneling Method (NATM). For rational management of tunnels from planning to construction and maintenance stages, prediction, control and monitoring of displacements of and around the tunnel have to be performed with high accuracy. Computational method tools, such as finite element method, have been and are indispensable tool for tunnel engineers for many years. It is, however, a commonly acknowledged fact that determination of input parameters, especially material properties exhibiting nonlinear stress-strain relationship, is not an easy task even for an experienced engineer. Use and application of the acquired tunnel information is important for prediction accuracy and improvement of tunnel behavior on construction. Artificial Neural Network (ANN) model is a form of artificial intelligence that attempts to mimic behavior of human brain and nervous system. The main objective of this paper is to perform the deformation analysis in NATM tunnel by means of numerical simulation and artificial neural network (ANN) with field database. Developed ANN model can achieve a high level of prediction accuracy.

• International Journal of Fuzzy Logic and Intelligent Systems
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• 제12권3호
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• pp.226-231
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• 2012

Autoparking assistant systems are a new and very promising area in automotive systems engineering. Since the traffic in modern cities becomes more intense, it is getting harder for a driver. Those systems are necessary for an inexperienced one to find a proper parking slot, or to park in a narrow parking slot without damaging his car or the vehicles around. The implementation of autoparking assistant systems may reduce drivers' stress and make parking generally more comfortable. In addition, such system can be extremely useful for senior or disabled people or for drivers with reduced mobility. The implementation of autoparking assistant systems may increase the safety of the parking, and therefore the development of such systems is a highly-demanded task. We introduce an intelligent autoparking system that automatically generates trajectory for parking using a fuzzy logic. This paper consists of three parts. In first part we introduce trajectory generation method for parallel parking without collisions. Fuzzy-logic based trajectory generation algorithm is described in second part. Experimental results presented in the third part of the paper prove effectiveness of the proposed method.

• 산업경영시스템학회지
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• 제36권1호
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• pp.1-7
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• 2013

This study is aimed to investigate the association between anaerobic-aerobic exercise intensity and hand steadiness. Hand steadiness is the decisive contributor to affecting the job performance just as in the rifle shooting and archery in sports and the microscope-related jobs requiring hand steadiness in industries. In anaerobic exercise condition hand steadiness is measured through hand steadiness tester having 9 different diameter holes after each subject exerts 25%, 50%, 75%, and 100% of maximum back strength. In aerobic exercise occasion it is evaluated at each time heart rate reaches 115%, 130%, and 145% of reference heart rate measured in no task condition after they do jumping jack. The results indicate that an increased intensity in both types of exercise reduces hand steadiness, but hand steadiness at 25% of maximum back strength and 115% of reference heart rate is rather greater than at no exercise. Just as the relation between cognitive stress and job performance has upside-down U form, so does the association of physical loading to hand steadiness, which means that a little exercise tends to improve hand steadiness in comparison with no exercise.

• Safety and Health at Work
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• 제10권3호
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• pp.327-335
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• 2019

Background: There have been some concerns related to manual handling of large items in industry. Manual handling operations of large sheet metal may expose workers to risks related to efficiency as well as occupational safety and health. Large sheet metals are difficult to move and burdensome to lift/transfer, and handling the sharp sheet edges may result in contact stress and/or cut injuries on the workers. Methods: Through observation, interview, and immersive simulation activities, a few problems related to current handling of sheet metals were identified. A sheet metal trolley-lifter was then designed and fabricated to address these issues. A pilot study on the use of the developed trolley-lifter for handling sheet metals was conducted to compare between the new and traditional handling methods. Results: The pilot study of the trolley-lifter showed promising results in terms of improving the cycle time, manpower utilization, and working postures compared with the traditional handling method. Conclusion: The trolley-lifter offers an alternative solution to automation and a mechanized assistive device by providing a simple mechanism to assist the handling of sheet metals effectively and safely.

• Journal of Information Technology Applications and Management
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• 제26권1호
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• pp.77-93
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• 2019

Recently, office workers are increasingly aware of the right to disconnect because of the pressure from strong connections with Internet messengers. In this study, we examined the reason why the perception of the right to disconnect increases and how to deal with it. This research model is that smart working and psychological attachment from work affect right to disconnect, and that open communication and gender moderate the intensity of these effects. To verify this research model, survey questionnaires were distributed to workers in smart working environments, and 400 data were collected and analyzed using Smart-PLS. As results of data analysis, it was verified that smart working and psychological attachment from work had a significant influence on right to disconnect, that open communication group had a lesser effect of psychological attachment from work on right to disconnect than closed communication group, and that women had a lesser effect of psychological attachment from work on right to disconnect than men. Organizations need to maintain a desirable level of right to disconnect in order to improve the quality of working life. But, if it is impossible, They need to change the way of communication more openly so as to absorb the burden of strong connection by Internet. And they need to perform task assignment or stress relief policy reflecting gender characteristics.

• 한국IT서비스학회지
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• 제20권5호
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• pp.55-71
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• 2021

Technostress management is increasingly getting important as ICT advances and infiltrates every job and task. Especially with the advent of COVID-19, workers had to switch to teleworking utilizing ICT extensively. In this study, we developed a research model explaining antecedents and their impacts on technostress in telecommuting context, especially under the COVID-19 situation. The result revealed that techno-complexity, techno-invasion, and techno-overload are the dominant factors that affect the negative psychological responses in the COVID-19 situation. Among them, we found that techno-overload maintain the most significant influence. It is due to the lack of instant feedback on workload allocations in telework and the lack of adjustment period with the sudden shift to telecommuting. In the case of techno-complexity, employees seem to experience difficulty acquiring new technical skills. Finally, the techno-invasion came out significant, signifying the infiltration of working space by home-related activities. The emotion-focused coping strategy had a moderating effect. In contrast, the problem-focused coping strategy had no significant effect, indicating that an appropriate emotional coping strategy is more important for workers undergoing extreme changes in the work environment. Subsequently, practical and theoretical implications, limitations, and future research directions are discussed.

• 한국복합재료학회:학술대회논문집
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• 한국복합재료학회 2003년도 추계학술발표대회 논문집
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• pp.46-49
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• 2003

Cu have been widely used as signal transmission materials for electrical electronic components owing to its high electrical conductivity. However, it's size have been limited to small ones due to its poor mechanical properties, Until now, strengthening of the copper at toy was obtained either by the solid solution and precipitation hardening by adding alloy elements or the work hardening by deformation process. Adding the at toy elements lead to reduction of electrical conductivity. In this aspect, if carbon nanofiber is used as reinforcement which have outstanding mechanical strength and electric conductivity, it is possible to develope Cu matrix nanocomposite having almost no loss of electric conductivity. It is expected to be innovative in electric conduct ing material market. The unidirectional alignment of carbon nanofiber is the most challenging task developing the copper matrix composites of high strength and electric conductivity In this study, the unidirectional alignment of carbon nanofibers which is used reinforced material are controlled by drawing process in order to manufacture the intermediary materials for the carbon nanofiber reinforced Cu matrix nanocomposite and align mechanism as well as optimized drawing process parameters are verified via experiments and numerical analysis. The materials used in this study were pure copper and the nanofibers of 150nm in diameter and of $10~20\mu\textrm{m}$ In length. The materials have been tested and the tensile strength was 75MPa with the elongation of 44% for the copper it is assumed that carbon nanofiber behave like porous elasto-plastic materials. Compaction test was conducted to obtain constitutive properties of carbon nanofiber. Optimal parameter for drawing process was obtained by experiments and numerical analysis considering the various drawing angles, reduction areas, friction coefficient, etc Lower reduction areas provides the less rupture of cu tube is not iced during the drawing process. Optimal die angle was between 5 degree and 12 degree. Relative density of carbon nanofiber embedded in the copper tube is higher as drawing diameter decrease and compressive residual stress is occurred in the copper tube. Carbon nanofibers are moved to the reverse drawing direct ion via shear force caused by deformation of the copper tube and alined to the drawing direction.

• 한국산림과학회지
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• 제104권2호
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• pp.277-284
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• 2015

본 연구는 산림치유가 청소년 인터넷 중독 위험군의 신경인지, 심리사회, 생리적 측면에 어떤 영향을 주는지 알아보고자 진행되었다. 이를 위해 2013년 5월부터 7월까지 서울시 지역사회 및 상담센터, 병원에 왕래하는 청소년들을 대상으로 한국형 인터넷 중독 자가진단척도를 실시하였고, 본 척도의 기준에 따라 고위험 사용자군, 잠재적 위험 사용자군, 일반 사용자군으로 분류하였다. 이후 고위험 사용자군과 잠재적 위험 사용자군을 인터넷 중독 위험군으로 정의하였고, 본 연구의 대상자로 포함하였다. 산림치유캠프 참여와 대조군 검사는 서면으로 본인과 부모의 동의 및 참여의사를 밝힌 총 25명으로 진행되었으며, 무작위 배정을 통해 산림치유캠프 참여 13명, 대조군 검사 12명으로 분류하였다. 이들을 대상으로 신경인지적 측면은 Continuous Performance Task(CPT), 심리사회적 측면은 Kimberly S. Young Scale(KYS), Connor-Davidson Resilience Scale(RSC), Relationship Change Scale(RCS), 생리학적 측면은 Heart Rate Variability(HRV)와 Cortisol 검사를 실시하였고, 최종적으로 산림치유는 인터넷 중독 위험군의 신경인지적, 심리사회적 측면에 영향을 주는 것을 확인할 수 있었다. 신경인지적 측면의 경우 산림치유캠프에 참여한 집단은 산림치유캠프에 참여하지 않은 집단에 비해 지속수행검사(CPT)의 주의력 결핍(AQ), 청각주의력 결핍(AAQ)에서 감소효과를, 청각조심성(AP)에서는 향상 효과를 보였다. 심리사회적 측면에서는 대인관계 변화척도(RCS)에서 산림치유캠프 집단이 통계적으로 유의미하게 증가되었으며, 인터넷 중독(KYS)과 회복탄력성(RSC)에서는 통계적으로 완화 및 향상되는 경향성을 보였다. 생물학적인 측면에서는 심박수(HR)의 증가를 제외하고 통계적으로 유의미한 결과는 나타나지 않았다.