• Proceedings of the KAIS Fall Conference
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• 2001.05a
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• pp.129-134
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• 2001

본 논문에서는 자동차 계기판 지시계 구동용 액츄에이터 연구의 일환으로써 소형 2상 스텝모터에 대하여 유한요소 수치해석을 이용한 설계, 해석 및 One Chip을 이용한 유량, 온도, RPM 및 속도 지시계 동시제어용 전용 구동 IC를 설계하였다. 일반적으로 자동차 계기판에 사용되어지고 있는 지시계의 구동원으로 코일형의 액츄에이터를 사용하고 있으나, 동작구간내의 선형성 및 속응성 저하와 구조상 큰 체적으로 인한 공간확대의 문제가 야기되어지고 있다. 따라서, 본 연구에서는 고 에너지 밀도를 갖는 소형의 영구자석과 저 손실 특성을 갖는 정밀 기어부 설계를 통하여 경량. 박형의 PM형 스텝모터를 설계하였으며. 또한 다수 모델 제어용 전용 드라이버 IC 설계 및 제작을 하였다. 실제로 제작한 모델을 대상으로 특성평가를 행하였으며, 이로부터 높은 선형성 및 고정밀도와 저소음 특성을 갖는 자동차 계기판 지시계용 구동원 및 드라이버의 활용 가능성을 확인 할 수 있었다.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2005.05a
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• pp.419-422
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• 2005

Many process parameters have an effect on the auto-body panel forming process. A well-designed blank shape causes the material to flow smoothly, reduces the punch and yields a product with uniform thickness distribution. Therefore, the determination of an initial blank shape plays the important role of saving time and cost in the auto-body panel forming process. For these reasons, some approaches to estimate the initial blank shape have been implemented in this paper, the one-step approach by using a finite element inverse method will be introduced to predict the initial blank shape the developed program is applied to auto-body panel forming.

• Korean Journal of Optics and Photonics
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• v.17 no.6
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• pp.500-506
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• 2006

An optical fiber displacement sensor has the advantages of relatively simplicity, cheap, small probe size and immunity against environmental perturbation. The working principle of the sensor is based on the intensity modulation that is detection light intensity reflecting from the surface being measured. This paper presents the mathematical model of displacement measurement mechanism of this sensor type. The theoretical and experimental data are compared to verify the model in describing the realistic approach to sensor design. Finally, the analysis results show that displacement response characteristics such as sensitivity, measuring range are easily modified by principal design parameters such as magnitude of optical Power, diameter of optical fiber core and distance between transmitting fiber and receiving fiber.

• Journal of the Korean Society for Precision Engineering
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• v.22 no.2
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• pp.89-97
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• 2005

Thin plate correction of forming process that it is nowadays smile change of simple contact surface as it becomes possible that forecast dictionary numerically exactly to analyze comparative big comp displacement real industry spot problems between complicated and abnormal curved line shapes and thin plate and die more reliable and need many efforts yet economical analysis method is required and develops this efficient algorithm. This research analyzes correction of forming and examined possibility and validity of spot application using One-Step Finite Element Method. Its application is being increased especially in the automotive industrial area for the cost reduction, weight saving, and improvement of strength.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2005.10a
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• pp.414-417
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• 2005

Many process parameters have an effect on the auto-body panel forming process. A well-designed blank shape causes the material to flow smoothly, reduces the punch and yields a product with uniform thickness distribution. Therefore, the determination of an initial blank shape plays the important role of saving time and cost in the auto-body panel forming process. For these reasons, some approaches to estimate the initial blank shape have been implemented in this paper, the one-step approach by using a finite element inverse method will be introduced to predict the initial blank shape the developed program is applied to auto-body panel forming.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.06a
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• pp.585-588
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• 2005

Many process parameters have an effect on the auto-body panel forming process. A well designed blank shape causes the material to flow smoothly, reduces the punch and yields a product with uniform thickness distribution. Therefore, the determination of an initial blank shape plays the important role of saving time and cost in the auto-body panel forming process. For these reasons, some approaches to estimate the initial blank shape have been implemented, in this paper The one-step approach using a finite element inverse method will be introduced to predict the optimal forming with changing of blank pressure the developed program is applied to auto-body panel forming.

• Proceedings of the Korean Vacuum Society Conference
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• 2011.02a
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• pp.497-498
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• 2011

나노입자는 벌크 재료와는 다른 광학적, 전기적, 촉매적 특징 때문에 최근 많은 연구가 이루어지고 있다. 나노유체의 성질은 나노입자의 크기와 형상, 분산성등과 같은 여러 요인에 의해서 결정되어진다. 이러한 나노입자의 특징 때문에 여러 응용분야에서 활용되어지고 있다. 예를 들면, 일반 유체에 나노입자를 분산시키면, 열전도도와 대류열전달효과가 증대되어 진다. 이러한 나노유체의 제조법으로는 크게 두 가지로 분류되어 있다. 투스텝법은 환원법 혹은 기계적으로 제작한 나노입자를 일반 유체에 혼합시킨 후 분산을 시켜 제조하는 제조법이다. 원스텝법은 투스텝법과는 달리 한번에 나노유체를 제조하는 제조법이다. 일반 유체에서 나노유체를 제조함과 동시에 분산을 시켜서 제조한다. 최근, 유체내에서 나노유체를 제조함과 동시에 분산을 시켜 나노유체를 제조하는 새로운 기술인 유체 플라즈마법이 개발되었다. 하지만, 유체 플라즈마의 일반적인 거동과 해석이 명확하게 규명되지 않은 상태이다. 본 연구에서는 유체 플라즈마의 발생 메카니즘 규명을 위한 방전 시간, 전압, 단극 직류 전력, 극간거리에 따른 유체 플라즈마의 특징을 OES와 오실로스코프를 이용하여 측정하였다. 또한, 제조된 나노유체의 특징을 UV-vis nir spectropgotometer, HR-TEM, zeta-potential, EDS, ICP-OES, KD2 pro and lambda로 측정하였다. 유체 플라즈마를 각 조건에 따라 발생시켰고, 나노유체를 성공적으로 제조하였다. 유체 플라즈마의 주요 발생 원소는 산소와 수소이온으로 측정되었다. 유체 플라즈마의 강도는 전기에너지가 증가함에 따라서 증가함으로 측정되었다. 제조된 나노입자의 크기는 유체 플라즈마의 강도가 증가함에 따라서 감소하였고, 대부분의 나노입자의 형상은 구형으로 제조되었다. 나노유체의 분산안정성 또한 유체 플라즈마의 강도가 증가함에 따라서 증가하였다. 직경이 $18.1{\pm}5.0$ nm인 나노유체의 열전도도는 3%로 측정되었다. 유체 플라즈마에 의한 나노유체의 제조 메카니즘을 다음과 같이 제안한다. 유체내에서 전기에너지 인가에 따른 이온과 전자의 흐름은 유체 플라즈마를 발생시킨다. 기본 유체는 물이므로 유체 플라즈마의 주요 발생 원소는 수소와 산소이며, 인가되는 전기에너지량이 증가함에 따라서 이온과 전자의 흐름이 증가됨으로서 유체 플라즈마의 강도가 증가함으로 추측한다. 유체 플라즈마 발생은 전자의 흐름과 관계되어진다. 따라서, 유체내에 존재하는 전구체에 전자가 제공되어짐에 따라서 금 입자를 환원시켜 입자가 형성된다. 또한, 유체 플라즈마는 나노입자를 음전하로 대전시켜 분산안정성의 확보가 되는 것으로 추측되어진다.

• Journal of the Korean Society for Precision Engineering
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• v.13 no.12
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• pp.86-98
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• 1996

An combined implicit/explicit scheme for the analysis of sheet forming problems has been proposed in this work. In finite element simulation of sheet metal forming processes, the robustness and stability of computation are important requirements since the computation time and convergency become major points of consideration besides the solution accuracy due to the complexity of geometry and boundary conditions. The implicit scheme dmploys a more reliable and rigorous scheme in considering the equilibrium at each step of deformation, while in the explict scheme the problem of convergency is elimented at thecost of solution accuracy. The explicit approach and the implicit approach have merits and demerits, respectively. In order to combine the merits of these two methods a step-wise combined implici/explicit scheme has been developed. In the present work, the rigid-plastic finite element method using bending energy augmented membraneelements(BEAM)(1) is employed for computation. Computations are carried out for some typical sheet forming examples by implicit, combined implicit/explicit schemes including deep drawing of an oil pan, front fender and fuel tank. From the comparison between the methods the advantages and disadvantages of the methods are discussed.

• Journal of Distribution Research
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• v.12 no.3
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• pp.1-21
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• 2007

This study introduces 'Free Market' that was recently developed in front of Hongik university. 'Free market', as a place for transactions for art products produced by artists or prospective artists, is held regularly every Saturday in front of Hongik university. This study collected data through in-depth interviews with participants and participant observations at the market to analyze the success factors of 'Free Market'. We described development process, unique characteristics of 'Free Market' and new experiential values that the market provide to the participants. This free market was introduced as roadside stand in the middle of 1990s when some artists started selling their works. It passed through the growth stage after it staged the event that had mixed characteristics of 'flee market' and 'art market' at local festivals in 2001. In 2002 Sin-Chon culture forum directedculture-oriented market and the market has been developed as a current 'Free Market'. Recently 'Free Market' is comprised of steps, artists, and customers who voluntarily participated in the market. The market is held regularly every Saturday and provide various types of programs for the participants. Major characteristics of this free market were summarized as 'complex space' and 'role transition', and these characteristics provided the participants new experiential values such as 'freedom', 'emergent experiences', 'social interaction' and 'hero of festivals' through the participant role. We interpret that 'Free Market' has been successfully settled down as a new type of retail store based on these new experiential values. Therefore, this case provides very useful implications that unique experiential values that a store provides to the customers can be major sources of store competitive advantages.