• 한국자동차공학회논문집
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• 제17권2호
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• pp.98-103
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• 2009

The environment and energy related problem has become one of the most important global issues in recent years. One of the most effective ways of improving the fuel efficiency of automobiles is the weight reduction. In order to obtain this goal the hydroforming technology has been adapting for the high strength steel and its application is being widened. In present study, the chassis components (mainly cross members of engine cradle) simulation and development by hydroforming technology to apply high strength steel having tensile strength of 440 MPa grade is studied. In the part design stage, it requires feasibility study and process design aided by CAE (Computer Aided Design) to confirm hydroformability in details. Overall possibility of hydroformable chassis parts could be examined by cross sectional analyses. Moreover, it is essential to ensure the formability of tube material on every forming step such as pre-bending, performing and hydroforming. In the die design stage, all the components of prototyping tool were designed and interference with press was investigated from the point of geometry and thinning.

• 공학교육연구
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• 제3권1호
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• pp.3-11
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• 2000

본 논문에서는 새로운 교육환경에 적응하여 공학에 대한 일반 학생들의 학습동기를 유발, 진작 시키고 현행 대학교육 시스템이 가진 전공교육 부실의 문제점을 해결하는 차세대 교육시스템의 하나로 웹 기반 하이퍼미디어 코스웨어를 개발한 경험과 이를 실제활용한 교육시스템 HALS(Hypermedia Aided Learning System)에 대하여 구체적으로 소개한다. 이 웹기반 하이퍼미디어 코스웨어는 기존의 칠판과 분필로 대변되는 교육매체를 첨단정보통신 매체로 갈음하고 학생 개개인의 다양한 지적 호기심에 효과적으로 부응할 수 있는 전력계통공학 강의가 가능하도록 설계되었다. 웹기반 하이퍼미디어 코스웨어에 의해 공학 강의의 단위 시간당 교육효과를 획기적으로 개선할 수 있으며 이를 통해 현행 교육제도가 가진 문제점들을 상당 부분 보완할 수 있을 것이다. 또한 본 논문에서는 이러한 HALS를 교육에 적용하여 학생들이 느끼는 HALS의 만족도, HALS 특성의 인지, 수업내용, 미래의 교육방향, 그리고 교수와의 상호작용의 필요성에 대하여 평가한 결과를 소개한다. 이러한 평가를 바탕으로 하여 HALS의 장점을 부각시키고 나아가 보완점을 탐색하여 교육의 질을 높일 수 있을 것이다.

• 대한치과기공학회지
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• 제44권3호
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• pp.67-75
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• 2022

Purpose: This study aimed to comparatively evaluate the stress distribution of bones surrounding the implant system to which both titanium and polyetheretherketone (PEEK) abutments are applied using a three-dimensional finite element analysis. Methods: The three-dimensional implant system was designed by the computer-aided design program (CATIA; Dassault Systemes). The discretization process for setting nodes and elements was conducted using the HyperMesh program (Altair), after finishing the design of each structure for the customized abutment implant system. The results of the stress analysis were drawn from the Abaqus program (Dassault Systèmes). This study applied 200 N of vertical load and 100 N of oblique load to the occlusal surface of a mandibular first molar. Results: Under external load application, the PEEK-modeled dental implant showed the highest von Mises stress (VMS). The lowest VMS was observed in the Ti-modeled abutment screws. In all groups, the VMS was observed in the crestal regions or necks of implants. Conclusion: The bones surrounding the implant system to which the PEEK abutment was applied, such as the cortical and trabecular bones, showed stress distribution similar to that of the titanium implant system. This finding suggests that the difference in the abutment materials had no effect on the stress distribution of the bones surrounding implants. However, the PEEK abutments require mechanical and physical properties improved for clinical application, and the clinical application is thought to be limited.

• Journal of Nutrition and Health
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• 제35권8호
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• pp.886-895
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• 2002

Introduction and application of virtual education has been rapidly increased in these days. A variation of information communication technology has an effect on education in interconnect with network as internet in the world that exceed the limit of time and regional. Computer and network communication technology through the medium of internet make an entrance cyber education as a new education paradigm. It must be affective on learner who have various educational characteristics and requirements. It begins to appear quality, quantity improvements of knowledge and the development of information technology that web based cyber education. This study was conducted to develop the web based education program and to evaluate the effectiveness of learning satisfaction and accomplishment and to compare the cyber lecture system with the traditional lecture system During the second semester of 2001, this study was investigated 317 registered students in a "Food and Culture" class at Kyungwon University. The data were obtained from pre and post-study with self-administered questionnaire. The evaluation and satisfaction score of students who were registered in cyberclass was negative tendency to compare pre with post-test scores, because of insuffciency of computer-aided lecture system. The major problem was inconvenient in checking system for connecting times in cyberclass which was one of evaluation point in final score. Another problem was frequently disconnection during cyber studying and not to concentrate each time in the cyber lecture because of eye fatigue, boring due to less interesting contents than other newly developed web-site. The students was prefer to mix type of the cyber and traditional lecture type class. The result of final score an each class, the score of cyber class (71.36 $\pm$ 22.44) was significantly lower than other groups (mixed type : 76.66 $\pm$ 19.99, traditional type :79.17 $\pm$ 15.72) (p < 0.05). Cyber class was attempted to present a useful and interesting teaching and learning tool which can be applied successfully in a longer term. The result suggest that various teaching and learning strategies should be developed considering the fact that the student learn alone most in time.t in time.

• International Journal of Naval Architecture and Ocean Engineering
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• 제6권2호
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• pp.297-306
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• 2014

The paper presents the numerical analysis of wave run-up over rubble-mound breakwaters covered by antifer units using a technique integrating Computer-Aided Design (CAD) and Computational Fluid Dynamics (CFD) software. Direct application of Navier-Stokes equations within armour blocks, is used to provide a more reliable approach to simulate wave run-up over breakwaters. A well-tested Reynolds-averaged Navier-Stokes (RANS) Volume of Fluid (VOF) code (Flow-3D) was adopted for CFD computations. The computed results were compared with experimental data to check the validity of the model. Numerical results showed that the direct three dimensional (3D) simulation method can deliver accurate results for wave run-up over rubble mound breakwaters. The results showed that the placement pattern of antifer units had a great impact on values of wave run-up so that by changing the placement pattern from regular to double pyramid can reduce the wave run-up by approximately 30%. Analysis was done to investigate the influences of surface roughness, energy dissipation in the pores of the armour layer and reduced wave run-up due to inflow into the armour and stone layer.

• 한국산업융합학회 논문집
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• 제21권1호
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• pp.29-36
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• 2018

Low pressure casting process for unidirectional carbon fiber reinforced aluminum (UD-CF/Al) composites which is an infiltration route of molten Al into porous UD-CF preform has been a cost-effective way to obtain metal matrix composites (MMCs) but, easy to cause non-uniform fiber distribution as CF clustering. Such clustered CFs have been a problem to decrease the density and thermal conductivity (TC) of composites, due to the existence of pores in the clustered area. To obtain high thermal performance composites for heat-sink application, the relationship between fiber distribution and porosity has to be clearly investigated. In this study, the CF distribution was evaluated with quantification approach by using two-dimensional spatial distribution method as local number 2-dimension (LN2D) analysis. Note that the CFs distribution in composites sensitively changed by sizes of Cu bridging particles between the CFs added in the UD-CF preform fabrication stage, and influenced on only $LN2D_{var}$ values.

• 한국CDE학회논문집
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• 제6권1호
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• pp.17-23
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• 2001

Lasting machines for shoe manufacturing are continuously developed with the aid of automation and CAM(Computer Aided Manufacturing). Although automation and CAM techniques have tremendously reduced the labor in shoe manufacturing, there still remain some parts manufactured by experts. In order to enhance the capability and efficiency of machines for labor-free shoe manufacturing, CAD data of a shoe last is essential. While CAD datarization takes the fundamental role in the shoe design and manufacturing, there has been little research for the CAD datarization of a shoe last. In this paper, a new procedure for CAD datarization of a shoe last using finite element patches and a tension sl)line method is proposed for application to shoe manufacturing machines. The outer line of a shoe-last sole is interpolated by a tension spline method and bonding lines are extracted from the shoe CAD data. Data set for a control algorithm of the tasting machine can be produced from the CAD data.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2005년도 춘계학술대회 논문집
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• pp.915-918
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• 2005

Advances in Information Technology and in Biomedicine have created new uses for CAD technology with many novel and important biomedical applications. Such applications can be found, for example, in the design and modeling of orthopedics, medical implants, and tissue modeling in which CAD can be used to describe the morphology, heterogeneity, and organizational structure of tissue and anatomy. CAD has also played an important role in computer-aided tissue engineering for biomimetic design, analysis, simulation and freeform fabrication of tissue scaffolds and substitutes. And all the applications require precision geometry of the organs or bones of each patient. But the geometry information currently used is polygon model with none solid geometry and is so rough that it cannot be utilized for accurate analysis, simulation and fabrication. Therefore a case study is performed to deduce a transformation method to build free form surface from a rough polygon data or medical images currently used in the application. This paper describes the transformation procedure in detail and the considerations for accurate organ modeling are discussed.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2004년도 춘계 학술대회논문집
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• pp.224-229
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• 2004

The objective of this work is not only to perform feasibility studies on the CFD (computational fluid dynamics) analysis for the capillary system design but also to provide an enhanced understanding of the autonomous capillary flow. The capillary flow is evaluated by means of the commercial CFD software of FLUENT, which includes the VOF (volume-of-fluid) model for multiphase flow analysis. The effect of wall adhesion at fluid interfaces in contact with rigid boundaries is considered in terms of static contact angle. Feasibility studies are first performed, including mesh-resolution influence on pressure profile, which has a sudden increase at the liquid/gas interface. Then we perform both 2D and 3D simulations and examine the transient nature of the capillary flow. Analytical solutions are also derived for simple cases and compared with numerical results. Through this work, essential information on the capillary system design is brought out. Our efforts and initial success in numerical description of the microfluidic capillary flows enhance the fundamental understanding of the autonomous capillary flow and will eventually pave the road for full-scale, computer-aided design of microfluidic networks.

• Journal of Electrical Engineering and Technology
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• 제12권5호
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• pp.1805-1811
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• 2017

Recently, DC systems are considered as efficient electric power systems for renewable energy based clean power generators. This discloses several critical issues that are required to be considered before the installation of the DC systems. First of all, voltage/current switching stress, which is aggravated by large fault current, might damage DC circuit breakers. This problem can be simply solved by applying a superconducting fault current limiter (SFCL) as proposed in this study. It allows a simple use of insulated-gate bipolar transistors (IGBTs) as a DC circuit breaker. To evaluate the proposed resistive type SFCL application to the DC circuit breaker, a DC distribution system is composed of the practical line impedances from the real distribution system in Do-gok area, Korea. Also, to reflect the distributed generation (DG) effects, several DC-to-DC converters are applied. The locations and sizes of the DGs are optimally selected according to the results of previous studies on DG optimization. The performance of the resistive type SFCL applied DC circuit breaker is verified by a time-domain simulation based case study using the power systems computer aided design/electromagnetic transients including DC (PSCAD/ EMTDC(R)).