• International Journal of Air-Conditioning and Refrigeration
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• 제14권3호
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• pp.94-101
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• 2006

A theoretical investigation to find thermodynamically optimum design conditions of conduction-cooled Peltier current leads is performed. A Peltier current lead (PCL) is composed of a thermoelectric element (TE), a metallic lead and a high temperature superconductor (HTS) lead in the order of decreasing temperature. Mathematical expressions for the minimum heat flow per unit current crossing the TE-metal interface and the minimum heat flow per unit current from the metal lead to the joint of the metal and the HTS leads are obtained. It is shown that the temperature at the TE -metal interface possesses a unique optimal value that minimizes the heat flow to the joint and that this optimal value depends on the material properties of the TE and the metallic lead but not the joint temperature nor electric current. It is also shown that there exists a unique optimal value for the joint temperature between the metal and the HTS leads that minimizes the sum of the power dissipated by ohmic heating in the current leads and the refrigerator power consumed to cool the lead, for a given length of the HTS.

• 한국CDE학회논문집
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• 제15권4호
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• pp.253-260
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• 2010

This paper presents algorithms for computing offsets of freeform curves. The approach first divides the original curve into several segments at the inflexion points. Based on the obtained new control polygon and its offsets, quadratic trigonometric splines are constructed to approximate the offset curves. Finally, the shape parameter value of trigonometric spline is determined to satisfy the required tolerance. The degree of the output curve is two, independent of the original curve's degree. Because of the great controllability, the proposed method can generate a completely overestimating offset curve by adjusting the value of the shape parameter, which guarantees no overcutting in NC machining. Furthermore, it also produces the lowest number of control points compared with other works.

• International Journal of CAD/CAM
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• 제6권1호
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• pp.167-172
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• 2006

Recently, wire-EDM became a necessity for many engineering applications, particularly in the dies making. No-Core cut process is helpful for operations in which falling slug can jam the machine or wire. In this paper a proposed CAM system (called NCPP) is introduced, to overcome the limitations of the existing CAM systems in the machining of No-Core cut. The proposed CAM system (NCPP) provides pocketing of No-core cut and optimal selection of the position of starting hole (wire threading point), to minimize toolpath length. It was written for data exchange between CAD-CAM-CNC machines. This data model will become part of the ISO (Data model for Computerized Numerical Controllers) international standard. The NCPP system has been implemented in Visual C++. Many examples are used to illustrate NCPP system. The results show that, NCPP saves the machining time by significant value. This value depends on the shape and complexity of the workpiece that is being cut.

• 한국CDE학회논문집
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• 제6권3호
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• pp.184-192
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• 2001

In this paper we present a remeshing algorithm for irregular meshes with boundaries. The irregular meshes are approximated by regular meshes where the topological regularity is essential for the multiresolutional analysis of the given meshes. Normal meshes are utilized to reduce the necessary data size at each resolution level of the regularized meshes. The normal mesh uses one scalar value, i.e., normal offset value which is based on the regular rule of a uniform subdivision, while other remeshing schemes use one 3D vector at each vertex. Since the normal offset cannot be properly used for the boundaries of meshes, we use a combined subdivision scheme which resolves a problem of the proposed normal offset method at the boundaries. Finally, we show an example to see the effectiveness of the proposed scheme to reduce the data size of a mesh model.

• 대한환경공학회지
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• 제38권6호
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• pp.334-342
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• 2016

기존의 에코디자인은 제품의 환경성 측면만을 고려하여 수행하였다. 이는 에코디자인 수행 시 제품의 환경측면 분석을 통해 파악된 주요 부품이 개선 대상이었다는 것을 의미한다. 나아가 최근 경제성 측면까지 고려하여 에코디자인을 수행하고 있는데, 이는 주로 공급자의 입장이 반영된 에코디자인이며, 소비자의 입장이 제대로 반영된 에코디자인이라고 보기 힘들다. 따라서 소비자의 입장에서 얻을 수 있는 가치에 대한 지표인 UV (Utility Value)를 고려한 새로운 에코디자인이 필요하다. 따라서, 환경적 측면뿐만 아니라 제품의 경제적 측면과 소비자효용가치(Utility value, UV) 적 측면을 동시에 고려한 에코디자인 지수(Eco-Design Index, EDI) 는 에코디자인을 평가하는 새로운 대안이 될 수 있다. 이 연구의 목적은 제품의 환경성, 경제성 및 소비자효용가치를 고려하여 에코디자인 지수의 로직(Logic)을 제안하고, 이를 공용 복합기의 출력 기능을 수행하는 부품에 적용하여 그 의의를 알아보고자 하는 것이다. 이는, 공용 복합기 부품들의 Utility Value (UV), Life Cycle environmental impact (LCE), 및 Life Cycle Cost (LCC) 값을 정량화하여 EDI를 산정한 뒤, 이를 토대로 에코디자인의 개선대상이 되는 부품을 파악하는 에코디자인의 새로운 접근방법을 제시하는 것이다. 이 연구의 대상 제품인 8가지의 부품 중 롤러의 경우 환경성과 경제성 측면에서 가장 우수한 부품으로 나타났지만 UV 값은 8개 부품들 중 가장 낮았다. 롤러의 EDI 순위는 8개 부품 중 4위에 불과했다. 전사벨트는 환경성과 경제성 측면에서 각각 8위와 5위를 나타낸 반면, UV 값이 2번째로 높게 산정되어, EDI 순위는 8개 중 3위였다. 이것은 에코디자인 정도를 평가할 때에 환경성뿐만 아니라 경제성과 UV 측면 또한 반드시 고려해야 한다는 것을 의미한다.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2010년도 춘계학술대회 논문집
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• pp.483-484
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• 2010

Unit cabin means room, which is installed in the high value ship such as drill ship and FPSO, after pre-assembled. In order to develop the noise control design for a unit cabin, a variety of acoustic tests such as sound absorption, transmission, and radiated noise measurements were carried out by using the mock-up of living quarter. From the tests, it was found out that the combined noise level of a unit cabin could be dominated by the radiated noise from wall panel in low frequency range and the design guidelines for the noise control of unit cabin were fully established, such as the improvement of sound transmission loss between the cabin and corridor, and radiated cabin noise reduction.

• Journal of Power Electronics
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• 제9권4호
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• pp.623-630
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• 2009

This paper proposes a filter design guideline for grid-connected single-phase inverters. By analyzing the instantaneous voltage applied to the filter inductor, the switching ripple current through the filter inductor can be precisely calculated. Therefore, filter inductance can be designed accurately, which guaranties that the switching ripple current will be under the target value. The proposed filter design method is verified by experiment.

• 한국정밀공학회지
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• 제24권11호
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• pp.101-107
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• 2007

Jettability analysis using one-dimensional(1D) lumped parameter model has been investigated to design the industrial inkjet head with proper drop velocity and drop volume. By simplifying the inkjet head system into an equivalent electrical circuit, lumped model has been developed. Performance of the lumped model is verified by the comparison between measured results of droplet velocity and ejection volume and predicted value. Also, the jetting performance of an inkjet head is characterized by varying the design parameter and driving condition. As a result, simulation results shows good agreement with the experimentally measured value. The developed lumped model enables to easily understand the effect of dimension change and predict the jetting performance.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 1998년도 춘계학술대회논문집
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• pp.237-241
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• 1998

This study is concerned with the optimum blank design which is able to minimize earing phenomena. A new analytic method is proposed to determine the optimum blank shape only using the tension test and standard deep drawing tests. Introducing a dimensionless parameter related to the earing and using a Fourier analysis, the optimum blank shape can be obtained by R-value and the tested results. The theoretical results by the proposed method are good agreement with the experimental results through several deep drawing tests using steel as working materials.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2002년도 춘계학술대회논문집
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• pp.645-650
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• 2002

In this paper, new concept, low noise axial fan was developed. The fan was designed to operate at high-pressure condition inside the refrigerator. This fan - we call it Alpha fan - has small turbo blades at trailing edge of axial fan. These turbo blades make alpha fan operate at high pressure and low noise condition. In order to find out the optimal value of design parameters, 6-sigma method was used. The design parameters are ratio between inner and outer diameter, Height, Install angle and Install position of turbo blade. Optimal value of turbo blade was found out and the noise generated from this fan is reduced about 3dB(A).