• 대한전기학회:학술대회논문집
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• 대한전기학회 2005년도 제36회 하계학술대회 논문집 B
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• pp.1553-1555
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• 2005

This paper presents a design of lossless hybrid-type magnetically-levitated vehicle. The lossless hybrid-type system is implemented by a permanent magnet and electromagnet. The target plant consists of eight hybrid-type magnets and in the steady-state, no current is needed to support the load. The design procedure is described and the results of this work are shown.

• 대한기계학회논문집B
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• 제31권2호
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• pp.125-131
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• 2007

This paper presents guideline for a practical design of the hybrid system combining a pressurized solid oxide fuel cell and a gas turbine. Design of the hybrid system based on a virtually designed gas turbine was simulated using models for off-design operation of the gas turbine. Two system configurations, with different method for supplying reforming steam, are considered and their design characteristics are compared. A higher design cell temperature provides better system performance. However, there exists a maximum allowable design cell temperature because the operating point of the compressor approaches the surge point with increasing fuel cell temperature. Increased pressure loss at the fuel cell moves the compressor operating point toward the surge point and reduces system performance.

• 한국수자원학회논문집
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• 제55권spc1호
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• pp.1271-1282
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• 2022

상수관망 최적설계는 사용자가 설정한 목적에 따라 다양하게 사용된다. 상수관망 최적설계는 비용의 최소화 및 관의 제작 시 발생하는 에너지 최소화 등 목적이 다양하게 존재한다. 본 연구에서는 Modified Hybrid Vision Correction Algorithm (MHVCA)을 기반으로 다양한 상수관망에 대한 비용 최적설계를 진행하였다. 또한 새로운 평가지표인 Best Rate (BR)를 제안하였다. BR은 K-mean Clustering Algorithm을 기반으로 개발된 평가지표이다. BR을 통해 상수관망 최적설계에 사용된 각 알고리즘의 최적 설계안 탐색 가능성에 대한 비교를 하였다. 다양한 관망에 대한 MHVCA의 최적설계 결과를 Vision Correction Algorithm (VCA) 및 Hybrid Vision Correction Algorithm (HVCA)과 비교하였다. MHVCA는 VCA 및 HVCA보다 낮은 비용의 설계안을 탐색하였다. 또한 MHVCA는 낮은 비용의 설계안을 탐색할 확률이 VCA 및 HVCA보다 높았다. MHVCA는 본 연구에서 적용한 비용 최소화를 위한 상수관망 최적설계 뿐만이 아닌 다양한 목적을 위한 상수관망 최적설계에 적용할 경우 좋은 결과를 나타낼 수 있을 것이다.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2003년도 춘계학술대회
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• pp.729-733
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• 2003

Hybrid RMU is a kind of power circuit breaker and protects electric devices from over-current. In this paper we built a dynamic model of RMU driving mechanism using ADAMS and performed a optimal design of several design parameters. Finally we developed a prototype of RMU driving mechanism through results of analysis and confirmed it to satisfy design requisitions.

• Earthquakes and Structures
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• 제9권6호
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• pp.1251-1272
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• 2015

It is widely recognized that the preferred yielding mechanism for a hybrid coupled wall structure is that all coupling beams over the height of the structure yield in shear prior to formation of plastic hinges in structural walls. The objective of the study is to provide feasible approaches that are able to promote the preferred seismic performance of hybrid coupled walls. A new design methodology is suggested for this purpose. The coupling ratio, which represents the contribution of coupling beams to the resistance of system overturning moment, is employed as a fundamental design parameter. A series of nonlinear time history analyses on various representative hybrid coupled walls are carried out to examine the adequacy of the design methodology. While the proposed design method is shown to be able to facilitate the desired yielding mechanism in hybrid coupled walls, it is also able to reduce the adverse effects caused by the current design guidelines on the structural design and performance. Furthermore, the analysis results reveal that the state-of-the-art coupled wall design guidelines could produce a coupled wall structure failing to adequately exhaust the energy dissipation capacity of coupling beams before walls yield.

• International Journal of Naval Architecture and Ocean Engineering
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• 제7권1호
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• pp.41-55
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• 2015

This study is proposed a new hybrid mount having a moving-magnet type electromagnetic actuator to reduce the vibration transmitted from naval shipboard equipment to the structure of the ship's hull. Optimal design specifications are determined through experimental analysis. The detailed design of the hybrid mount is determined through several design steps with electromagnetic numerical analysis using Maxwell Software(S/W). The hybrid mount that combines a rubber mount and an electromagnetic actuator has a fail-safe function for shock resistance. The mount is fabricated and tested using a universal testing machine to evaluate the design specifications. Finally, numerical simulation of the hybrid mount is performed to confirm control performance and applicability.

• Steel and Composite Structures
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• 제13권1호
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• pp.47-70
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• 2012

To enhance cable stiffness, this paper proposed a combined application of carbon fiber reinforced polymers (CFRP) and steel materials, resulting in a novel type of hybrid stay cable system especially for the cable-stayed bridges with main span lengths of 1400~2800 m. In this combination, CFRP materials can conserve all their advantages such as light weight and high strength; while steel materials help increase the equivalent stiffness to compensate for the low elastic modulus of CFRP materials. An increase of the equivalent stiffness of the hybrid stay cable system could be further obtained with a reasonable increase of its safety factor. Following this concept, a series of parametric studies for the hybrid stay cable system with the consideration of stiffness and cost were carried out. Three design strategies/criteria, namely, best equivalent stiffness with a given safety factor, highest ratio of equivalent stiffness to material cost with a given safety factor, and best equivalent stiffness under a given cost were proposed from the stiffness and cost viewpoints. Finally, a comprehensive design procedure following the proposed design strategies was suggested. It was shown that the proposed hybrid stay cable system could be a good alternative to the pure CFRP or traditional steel stay cables in the future applications of super long span bridges.

• 한국수소및신에너지학회논문집
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• 제18권1호
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• pp.60-66
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• 2007

In terms of the vehicle efficiency, a fuel cell hybrid system has advantages compared to a conventional internal combustion engine and a fuel cell alone-powered system. The efficiency of the fuel cell hybrid vehicle mainly depends on the maximum power of the fuel cell and therefore it is important to decide the design value of the fuel cell maximum power. In this paper, to estimate the performance of the fuel cell hybrid mini-bus in the design phase the simulator based on the models for the fuel cell stack, the electric battery, the fuel cell balance of plant, the controller, and the vehicle itself is proposed. Additionally, the hybrid mini-bus efficiencies with several different fuel cell powers are simulated for a city driving schedule and are compared on another. Consequently, the proposed simulation scheme is useful to determine the best design value of the fuel cell hybrid vehicles.

• 대한기계학회논문집B
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• 제31권5호
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• pp.448-456
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• 2007

Performance of PEM fuel cell systems and hybrid systems combining a PEMFC with a gas turbine have been evaluated. Two different reforming methods(steam reforming and autothermal reforming) were considered. Performances of fuel cell systems with two reforming methods were compared and effects of various design parameters on the system performance were investigated. Configurations of PEM fuel cell systems with two reforming methods have been revised to accommodate a gas turbine, resulting in PEMFC/GT hybrid systems. Performance of the hybrid systems were analyzed and compared with those of PEM systems. Influences of major design parameters on the hybrid system performance were also investigated.

• International Journal of Aeronautical and Space Sciences
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• 제18권4호
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• pp.780-787
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• 2017

The propellant grain configuration is a design variable that determines the shape and performance of a solid rocket motor. Grain configuration variables have complicated effects on the motor performance; so the global optimization problem has to be solved in order to design the configuration variables. The grain performance has been analyzed by means of the grain burn-back and internal ballistic analysis, and the optimization technique searches for the configuration variables that satisfy the requirements. The deterministic and stochastic optimization techniques have been applied for the grain optimization, but the results are imperfect. In this study, the optimization design of the configuration variables has been performed using the hybrid optimization technique, which combines those two techniques. As a result, the hybrid optimization technique has proved to be efficient for the grain optimization design.