• Journal of Welding and Joining
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• 제30권6호
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• pp.120-125
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• 2012

Because ships and offshore structures have very large dimensions and complicated shapes, it is difficult to determine the deformation or internal stress in the structure by simple lab tests. Thus, a rigorous analysis by using the computer simulation technology is essential for obtaining their distortions by considering the entire production process characteristics. The rapid development of computer technology made it possible to analyze the heat transfer phenomena, deformation and phase transformation in the welded joint. For large shell structures, shell elements modeling contributed primarily to this development. But if a welding is done by multi-pass, shell elements whose thickness are unchangeable can hard to describe the local situation. Recently, it was researched how to introduce the imaginary temperature for V grooved multi-layer butt welding in strain-boundary method (a kind of shrinkage methodologies). In the present study, we formulated the imaginary temperature for the double bevel and double V groove by considering the thickness change of each pass through the bead and the thickness directions simultaneously and also demonstrated the feasibility of the formula by applying it to the thermal distortion analysis of the erection process of crane pedestal.

• 농업과학연구
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• 제40권4호
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• pp.385-394
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• 2013

Short-term agricultural machinery rental system has been operated by agricultural extension organization of local government (agricultural technology center) and sponsored by Ministry of Agriculture, Food, and Rural Affairs, to improve utilization efficiency and save agricultural production cost through joint utilization of agricultural machinery. This study was conducted to analyze current status of the rental system operation and provide recommendations for future direction. Question survey was conducted for officers in charge of the rental system in the technology center, and strategic improvement was suggested through importance performance analysis (IPA). Survey results showed that 11 issues should be reformed or improved by 2015, which is not practically feasible. IPA analysis resulted that administration and manpower support, cooperation between federal and local organizations, and cooperation with other organizations should be focused for successful operation of the rental system. Issues that seem to happen after 2015 need to be handled as future research.

• 한국생산제조학회지
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• 제18권6호
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• pp.642-651
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• 2009

The history of excavator design is not long enough which still causes most of the design considerations to be focused on static analysis or simple functional improvement based on static analysis. However, the real forces experiencing on each component of excavator are highly transient and impulsive. Therefore, the prediction and the evaluation of the movement of the excavator by dynamic load in the early design stage through the dynamic transient analysis of the excavator and ensuring of design technique plays an importance role to reduce development-cost, shorten product-deliver, decrease vehicle-weight and optimize the system design. In this paper, Commercial software DADS and ANSYS help to develop the track model of the crawler type excavator, and to evaluate the performance and the dynamic characteristics of excavator with various simulations. For that reason, the track of crawler type excavator is modelled with DADS Track Vehicle Superelement, and the reaction forces on the track rollers were predicted through the driving simulation. Also, the upper frame and cabin vibration characteristics, at the low RPM idle state, were evaluated with engine rigid body modelling. And flexibility body effects were considered to determine the more accurate joint reaction forces and accelerations under the upper frame swing motion.

• 한국지능시스템학회논문지
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• 제17권4호
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• pp.500-505
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• 2007

현재 휴머노이드 로봇기술은 로봇의 제작과 기술의 구현에만 초점이 맞추어져 있으며, 로봇 개발을 위한 분석, 설계, 구현, 통합 등의 개발 메커니즘들에 대한 개방화된 방법론은 개발되어 않았다는 문제점이 있다. 본 논문에서는 현재까지 나타난 휴머노이드 로봇의 문제점을 극복하고, 미래형 로봇의 발전방향인 "개방화", "네트워크화", "모듈화" 개념을 만족하는 새로운 구조를 설계하기 위한 인간 팔의 형태학적 신경학적 모델을 제시하고 이를 기반으로 로봇의 각 관절 설계와 기구학적 모델에 의한 휴머노이드 로봇 팔의 설계 방법을 제시하였다.

• International Journal of Knowledge Content Development & Technology
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• 제9권3호
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• pp.43-61
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• 2019

The purpose of the study is to investigate the influence of demographic factors (age and job status), level of ICT skills possessed by respondents and ICT use on task performances of library personnel. The study employed correlation design. Thirteen public universities were purposely selected while total enumeration was adopted to study 248 library personnel made up of librarians and library officers in public university libraries in South-west, Nigeria. Data was collected by questionnaire. The study established significant positive correlation between age, job status, ICT skills and task performance. Also, Anova test found significant joint influence of age, job status, ICT skills and ICT use on task performances of respondents. The study further indicated that age, job status, ICT skills possessed by respondents and ICT use had relative significant influence on task performances of respondents. It is therefore recommended that, library personnel must leverage their demographics positively to bring about positive disposition to their jobs while all categories of staff must ensure they possessed the requisite ICT skills that will ginger ICT use for effective task performance.

• The Journal of Asian Finance, Economics and Business
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• 제8권3호
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• pp.997-1007
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• 2021

The last decade has seen the emergence of the idea of "sharing economy" as people are more aware of environmental issues. Although clothing businesses applying the model of sharing consumption have emerged recently, less research effort has been invested in this topic, especially in investigating young consumers' intention. The purpose of this study is to investigate factors driving Generation Z consumers' behavioral intention toward online fashion rental. In this research, a conceptual framework is proposed based on the Theory of Planned Behavior and Technology Acceptance Model. To test the research model and hypotheses, a survey of 375 students and pupils was conducted in Vietnam. All the scales' reliability and validity were assessed through Cronbach's Alpha and confirmatory factor analysis. Structural equation modeling was used to assess the relationship among constructs. The study results showed that attitude toward behavior, subjective norm and perceived behavioral control were positive contributors to Gen Z's intention to use online fashion rental. Besides, the positive relationships between attitude and two other factors - perceived usefulness and perceived ease of use - were also highlighted. Moreover, the findings provided empirical evidence for supporting the positive impact of interpersonal influence, e-WOM, and influencer e-marketing on subjective norm.

• Journal of Advanced Marine Engineering and Technology
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• 제29권8호
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• pp.891-898
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• 2005

Inertia welding is a solid-state welding process in which butt welds in materials are made in bar and in ring form at the joint race, and energy required lot welding is obtained from a rotating flywheel. The stored energy is converted to frictional heat at the interface under axial load. The quality of the welded joint depends on many parameters, including axial force, initial revolution speed and energy amount of upset. working time, and residual stresses in the joint. Inertia welding was conducted to make the large exhaust valve spindle for low speed marine diesel engine. superalloy Nimonic 80A for valve head of 540mm and high alloy SNCrW for valve stem of 115mm. Due to different material characteristics such as, thermal conductivity and flow stress. on the two sides of the weld interface, modeling is crucial in determining the optimal weld geometry and Parameters. FE simulation was performed by the commercial code DEFORM-2D. A good agreement between the Predicted and actual welded shape is observed. It is expected that modeling will significantly reduce the number of experimental trials needed to determine the weld parameters. especially for welds for which are very expensive materials or large shaft. Many kinds of tests, including macro and microstructure observation, chemical composition tensile , hardness and fatigue test , are conducted to evaluate the qualify of welded joints. Based on the results of the tests it can be concluded that the inertia welding joints of the superalloy exhaust valve spindle are better properties than the material specification of SNCrW.

• 대한기계학회논문집A
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• 제38권6호
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• pp.585-592
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• 2014

본 논문에서는 도마뱀 로봇 설계를 위한 생체운동 모사 다물체 동역학 시뮬레이터가 개발되었다. 시뮬레이터에 사용된 다물체-기구 동역학 모델은 상용 소프트웨어인 RecurDyn 에 쿠반에놀 도마뱀의 모션 캡쳐 데이터와 Micro-CT 데이터를 적용하여 생성되었다. 다양한 도마뱀의 보행 운동 특성 해석을 위해서 생체운동 시뮬레이터는 궤적 생성모듈, 역기구학 모듈, 역동역학 모듈로 구성된다. 궤적생성 모듈은 도마뱀의 속도에 따른 척추운동과 발 궤적을 생성한다. 또한, 도마뱀 로봇 설계를 위해서 역기구학을 통한 관절 각도 계산과 그를 통한 역동역학 해석으로 이동속도에 대한 요구 조인트 구동력을 생성한다.

• 한국콘텐츠학회논문지
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• 제11권12호
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• pp.619-628
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• 2011

일반적으로 비전기반 3차원 인체 포즈 인식 기술은 HCI(Human-Computer Interaction)에서 인간의 제스처를 전달하기 위한 방법으로 사용된다. 특수한 환경에서 단순한 2차원 움직임 포즈만 인식할 수 있는 2차원 포즈모델 기반 인식 방법에 비해 3차원 관절을 묘사한 포즈모델은 관절각에 대한 정보와 신체 부위의 모양정보를 선행지식으로 사용할 수 있어서 좀 더 일반적인 환경에서 복잡한 3차원 포즈도 인식할 수 있다는 장점이 있다. 이 논문은 인체의 3차원 관절 정보를 이용한 포즈 인식 기술을 인터페이스로 활용한 상호작용 게임 콘텐츠 개발에 관해 기술한다. 제안된 시스템에서 사용되는 포즈는 인체 관절 중 14개 관절의 3차원 위치정보를 이용해서 구성한 포즈 템플릿과 현재 사용자의 포즈를 비교해 인식된다. 이 방법을 이용하여 제작된 시스템은 사용자가 부가적인 장치의 사용 없이 사용자의 몸동작만으로 자연스럽게 게임 콘텐츠를 조작할 수 있도록 해준다. 제안된 3차원 인식 기술을 게임 콘텐츠에 적용하여 성능을 평가한다. 향후 다양한 환경에서 더욱 강건하게 포즈를 인식할 수 있는 연구를 수행할 계획이다.

• 마이크로전자및패키징학회지
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• 제12권1호
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• pp.9-16
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• 2005

This paper presents the development of new anisotropic conductive adhesives with enhanced thermal conductivity for the wide use of adhesive flip chip technology with improved reliability under high current density condition. The continuing downscaling of structural profiles and increase in inter-connection density in flip chip packaging using ACAs has given rise to reliability problem under high current density. In detail, as the bump size is reduced, the current density through bump is also increased. This increased current density also causes new failure mechanism such as interface degradation due to inter-metallic compound formation and adhesive swelling due to high current stressing, especially in high current density interconnection, in which high junction temperature enhances such failure mechanism. Therefore, it is necessary for the ACA to become thermal transfer medium to improve the lifetime of ACA flip chip joint under high current stressing condition. We developed thermally conductive ACA of 0.63 W/m$\cdot$K thermal conductivity using the formulation incorporating $5 {\mu}m$ Ni and $0.2{\mu}m$ SiC-filled epoxy-bated binder system to achieve acceptable viscosity, curing property, and other thermo-mechanical properties such as low CTE and high modulus. The current carrying capability of ACA flip chip joints was improved up to 6.7 A by use of thermally conductive ACA compared to conventional ACA. Electrical reliability of thermally conductive ACA flip chip joint under current stressing condition was also improved showing stable electrical conductivity of flip chip joints. The high current carrying capability and improved electrical reliability of thermally conductive ACA flip chip joint under current stressing test is mainly due to the effective heat dissipation by thermally conductive adhesive around Au stud bumps/ACA/PCB pads structure.