• Korean Chemical Engineering Research
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• v.55 no.6
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• pp.745-753
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• 2017

In this study, a design strategy is proposed to restore the distorted urban water cycle to the natural water cycle through the LID facility. This is accomplished by determining the optimal LID facility design capacity through which flow duration curves remain the same before and after urban development. A part of the Noksan National Industrial Complex in Busan was selected as the study area and EPA SWMM was constructed to simulate long-term stormwater for various land use scenarios and LID facility design capacity. In the case that the study area was assumed to be a forest area or an agricultural area before urban development, it was found that it was necessary to allocate 7.3% or 5.5% of the impervious area to the area of the bio-retention in order for the flow duration curve to remain the same as before urban development. As a result of the sensitivity analysis of the bio-retention design capacity according to regional rainfall characteristics, the design capacity of 3.8~5.5% of impervious area is needed for the development of agriculture area. Therefore, it can be seen that the optimum capacity can be significantly different according to regional rainfall characteristics. On the other hand, as a result of analyzing the sensitivity of the design capacity according to the variation of the depth of each layer constituting the bio-retention and the size of contributing catchment area, the sensitivity of the optimal design capacity with respect to the design specifications of the bio-retention and the size of contributing catchment area was not significant.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.12 no.4
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• pp.129-134
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• 1992

This paper presents the relation between risk and safety factor for optimal storm sewer design in urban area. For reliability analysis of the storm sewer, uncertainty of the various parameters of constituting equation determining the capacity and load of storm" sewer is considered and risk is determined. In this study, reliability analysis method is applied to Seongsan detention reservoir basin which area is $381,000m^2$ Darcy-Weisbach equation is used for determining capacity of the storm sewer and rational formula is used for determining load. Safety factor representing ratio of the sewer capacity and design flowrate is calculated, and relating with risk. Then risk and safety factor with return period is obtained and it is used for optimal design of storm sewer.

• Journal of the Earthquake Engineering Society of Korea
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• v.11 no.1 s.53
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• pp.11-19
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• 2007

This paper proposes an optimal design method of distribution and capacities of linear viscous dampers for vibration control of two adjacent buildings. The previous researches have dealt with suboptimal design problem under the assumption that linear viscous dampers are distributed uniformly or proportionally to the sensitivity of the modal damping ratio according to floors, whereas this study deals with global optimization problem in which the damping capacities of each floor are independently selected as design parameters. For this purpose, genetic algorithm to effectively search multiple design variables in large searching domains is adopted and objective function leading to the global optimal solutions is established through the comparison of several optimal design values obtained from different objective functions with control performance and damping capacity. The effectiveness of the proposed method is investigated by comparing the control performance and total damping capacity designed by the proposed method with those of the previous method. In addition, the time history analyses are performed by using three historical earthquakes with different frequency contents, and the simulation results demonstrate that the proposed method is an effective seismic design method for the vibration control of the adjacent structures.

• Proceedings of the KIPE Conference
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• 2013.07a
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• pp.173-174
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• 2013

전기장만으로 에너지를 전송하는 전계결합형 비접촉 충전기술은 송수신부를 매개하는 AC링크를 구성하는 전극쌍의 정전용량확보에 한계가 있으므로, 이를 잘 활용하기 위한 송수신회로가 요구된다. 따라서 본 논문에서는 이를 감안하여 전계결합형 에너지전송에 적합한 매칭변압기를 사용한 E급 송수신회로 구조를 제안한다. 제안된 구조에서 AC-링크 캐패시터의 낮은 정전용량을 감안한 최적 설계방식을 제안하고 회로설계에 따른 성능을 모의실험을 통해 예측한다.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.25 no.12
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• pp.693-699
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• 2013

This paper describes a method for size optimization of the major design variables for solar water heating systems at the stage of concept design. The widely used RETScreen simulation tool was used for optimization. Currently, the RETScreen tool itself does not provide a function for optimization of the design parameters. In this study, an optimizer was combined with the software. A comparative study was performed to evaluate the RETScreen-based approach with the case study of a solar heating system in an office building. The optimized results using the RETScreen model were compared to previously published results with the TRNSYS model. The objective function of the optimization is the life-cycle cost of the system. The optimized design results from the RETScreen model showed good agreement with the optimized TRNSYS results for the solar collector area and storage volume, but presented a slight difference for the collector slope angle in terms of the converged direction of the solutions. The energy cost, life-cycle cost, and thermal performance regarding collector efficiency, system efficiency, and solar fraction were compared as well, and the RETScreen model showed good agreement with the TRNSYS model for the conditions of the base case and optimized design.

• The Bulletin of The Korean Astronomical Society
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• v.37 no.2
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• pp.196.2-196.2
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• 2012

본 논문은 달착륙선의 개념설계를 위하여 고려한 전력시스템의 설계와 달착륙선의 지상시험모델용 추력기 밸브구동 전원장치 개발에 대해 기술하였다. 달착륙선의 임무특성을 고려하여 전력시스템의 구조를 검토하고, 극한의 온도환경에서 달착륙선의 임무수행을 위하여 필요한 전력에너지를 충분히 공급할 수 있도록 태양전지 배열기와 배터리의 용량, 그리고 전장품의 용량을 설계하였다. 특히 경량의 달착륙선 개발을 위하여 고효율의 태양전지를 이용한 태양전지 배열기와 리튬-이온 배터리를 검토하였다. 극한의 우주환경에서 태양전지배열기의 동작특성을 검토하고 생성될 수 있는 최대 전력을 분석하여 최적의 태양전지 배열기의 면적을 분석하고, 장시간의 월식을 고려하여 배터리의 방전특성에 따른 배터리의 전압특성을 검토하였다. 그리고 달착륙선의 전력시스템 개념설계의 타당성 검토를 위하여 유럽에서 개념설계 중인 달착륙선의 전력시스템 사양과 용량에 대해 비교검토를 수행하였다. 현재 개발중인 지상검증모델용 달착륙선의 전력시스템 설계와 추력기 밸브구동 전원장치의 개발에 관해 기술하였다. 지상검증용 전력시스템은 태양전지배열기의 장착 없이 배터리의 전력만을 사용하여 지상검증모델용 달착륙선의 부하에 전력을 공급할 수 있도록 설계되었다. 달착륙선 지상시험모델의 비행시간과 임무에 따른 부하특성을 고려하여 상용 리튬-이온 배터리의 용량을 선정하였으며, 부하의 전력을 고려하여 간단한 보호회로를 설계하였다. 그리고 지상검증용 전원시스템은 추력기의 밸브구동을 위한 추력기 밸브구동 전원장치, DC/DC 컨버터 전원 모듈, 모니터링 모듈, 그리고 위급상황에서 전원을 차단하기 위한 "Emergency STOP" 모듈로 구성되어 있다.

• Journal of the Korean Vacuum Society
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• v.10 no.4
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• pp.440-448
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• 2001

The operation properties of DBD plasma reactors were observed by using 20 kV square pulse at the cylindrical and planar type of reactors in the condition of air pressure. The optimum operation frequency $f_0$ which optimizes the efficiency of operation was found as such $f_0\proptoexp(-C)$ when the current-voltage curve and charge-voltage curve were observed. Using these properties the dissipated power was evaluated. The dissipated power at the optimum frequency of operation was varied as the value of capacitance which is dependent on the structure and the dielectric material of the reactor, and had the maximum value at the specific value of capacitance. With these value of capacitance, DBD reactors which has a high level of efficiency can be formed.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2010.11a
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• pp.299-300
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• 2010

• Journal of the Earthquake Engineering Society of Korea
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• v.10 no.3 s.49
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• pp.85-100
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• 2006

This paper proposes an optimal design method of linear viscous dampers for the seismic performance of two adjacent structures with different heights. Accordingly, connection method using diagonal bracing between two floors and connection method between two structures are considered, and the effectiveness of the latter method is confirmed through the comparison of the frequency response functions with respect to damping capacity. Moreover, optimal damping to minimize the response of the adjacent structures in the frequency domain is found. The sensitivity of natural frequency and modal damping according to the damper capacity at each floor is obtained for the optimally designed system. From the sensitivity analysis, the modal damping is evaluated to be very sensitive to the damper installed at higher floor. Therefore, sensitivity-based damping distribution method is proposed. Diagonal bracing connection method, uniform distribution method and sensitivity-based distribution method are compared to each other in terms of seismic performance. The comparative results demonstrate that the proposed method is an effective seismic design method for the adjacent structures.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.46 no.11
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• pp.50-55
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• 2009

In this paper, a distributed amplifier is designed using distributed network synthesis that provides the optimum absorption capability of a capacitance. Transfer functions of filters, which consist of the amplifier, are synthesized by a low-pass Chebyshev approximation. Capacitances that a filter network can absorb are calculated as a function of its minimum insertion loss(MIL) and ripple. Active devices in a distributed amplifier are modeled as equivalent circuits by using their S-parameters, and their equivalent capacitances are absorbed into filter structures by properly adjusting the MIL and ripple of a transfer function. As an application example, a distributed amplifier with the gain of about 12.5dB is designed that operates over the frequency range between 0.1 and 7.5GHz. Experimental results prove that distributed network synthesis, which considers capacitance absorption capability, is useful to the design of distributed amplifiers.