• 한국경영과학회:학술대회논문집
• /
• 대한산업공학회/한국경영과학회 1996년도 춘계공동학술대회논문집; 공군사관학교, 청주; 26-27 Apr. 1996
• /
• pp.83-86
• /
• 1996

In this paper we study the problem of augmenting a physical network to improve the topology for new survivable network architectures. We are given a graph G=(V,E,F), where V is a set of nodes that represents transmission systems which be interconnected by physical links, and E is a collection of edges that represent the possible pairs of nodes between which a direct transmission link can be placed. F, a subset of E is defined as a set of the existing direct links, and E/F is defined as a set of edges for the possible new connection. The cost of establishing network $N_{H}$=(V,H,F) is defined by the sum of the costs of the individual links contained in new link set H. We call that $N_{H}$=(V,H,F) is feasible if certain connectivity constrints can be satisfied in $N_{H}$=(V,H,F). The computational goal for the suggested model is to find a minimum cost network among the feasible solutions. For a k edge (node) connected component S .subeq. F, we charactrize some optimality conditions with respect to S. By this characterization we can find part of the network that formed by only F-edges. We do not need to augment E/F edges for these components in an optimal solution. Hence we shrink the related component into a node. We study some good primal heuristics by considering construction and exchange ideas. For the construction heuristics, we use some greedy methods and relaxation methods. For the improvement heuristics we generalize known exchange heuristics such as two-optimal cycle, three-optimal cycle, pretzel, quezel and one-optimal heuristics. Some computational experiments show that our heuristic is more efficient than some well known heuristics.stics.

• 전력전자학회논문지
• /
• 제18권2호
• /
• pp.131-137
• /
• 2013

In this paper, the phase-shift full-bridge DC/DC converter with fixed-phase operation inverter is proposed. The proposed circuit consists of two full-bridge inverters which are connected in parallel. While one full-bridge inverter operates as the fixed-phase, it regulates the output voltage by adjusting the phase of the other inverter. During the normal operation period, the proposed circuit makes the less amount of conduction loss of the primary switches and secondary synchronous rectifiers, as well as the less amount of the current ripple of the output inductor, than the conventional phase-shift full-bridge DC/DC converter does. Also, it achieves high efficiency by reducing the snubber loss of the secondary synchronous rectifier. To sum up, the present inquiry analyzes the theoretical characteristics of the proposed circuit, and shows the experimental results from a prototype for 450W power supply.

• 한국초전도ㆍ저온공학회논문지
• /
• 제6권2호
• /
• pp.20-24
• /
• 2004

Bi-2223 wire, the first-generation high temperature superconducting (HTS) wire, was successfully commercialized and various electrical machinery and equipment are actively being developed in many countries. Because its critical current is too small to realize the lossless conducting part of electric power system with a HTS wire, multi-HTS paths are used to enlarge the critical current of HTS system. Though the resistance generated in HTS wire by transport current is very small, the difference of it in multi-path is the additional reason which causes the non-uniform current sharing in multi-HTS path except the well known reason, the difference of inductance between each path. In this paper, experimental research on current sharing of multi-strand and multi-stacked HTS wire was implemented. The whole critical current of multi-HTS paths is not equal to sum of critical current of each path because of non-uniform current sharing occurred in this paths. It was verified experimentally that Bi-2223 wires have different resistance generated by same transport current even if they was manufactured in same progress of work. Current sharing phenomenon was affected by difference of resistance and self and mutual inductance.

• Smart Structures and Systems
• /
• 제12권5호
• /
• pp.501-521
• /
• 2013

This paper is concerned with static and dynamic shape control of a laminated Bernoulli-Euler beam hosting a uniformly distributed array of resistively interconnected piezoelectric patches. We present an analytical one-dimensional model for a laminated piezoelectric beam with material discontinuities within the framework of Bernoulli-Euler and extent the model by a network of resistors which are connected to several piezoelectric patch actuators. The voltage of only one piezoelectric patch is prescribed: we answer the question how to design the interconnected resistive electric network in order to annihilate lateral vibrations of a cantilever. As a practical example, a cantilever with eight patch actuators under the influence of a tip-force is studied. It is found that the deflection at eight arbitrary points along the beam axis may be controlled independently, if the local action of the piezoelectric patches is equal in magnitude, but opposite in sign, to the external load. This is achieved by the proper design of the resistive network and a suitable choice of the input voltage signal. The validity of our method is exact in the static case for a Bernoulli-Euler beam, but it also gives satisfactory results at higher frequencies and for transient excitations. As long as a certain non-dimensional parameter, involving the number of the piezoelectric patches, the sum of the resistances in the electric network and the excitation frequency, is small, the proposed shape control method is approximately fulfilled for dynamic load excitations. We evaluate the feasibility of the proposed shape control method with a more refined model, by comparing the results of our one-dimensional calculations based on the extended Bernoulli-Euler equations to three-dimensional electromechanically coupled finite element results in ANSYS 12.0. The results with the simple Bernoulli-Euler model agree well with the three-dimensional finite element results.

• 한국태양에너지학회 논문집
• /
• 제38권4호
• /
• pp.55-66
• /
• 2018

nZEH (net-Zero Energy House) is defined as a self-sufficient energy building where the sum of energy output generated from new & renewable energy system and annual energy consumption is zero. The electricity generated by new & renewable energy system with the form of distributed generation is preferentially supplied to electrical demand, and surplus electricity is transmitted back to grid. Due to the recent expansion of houses with photovoltaic system and the nZEH mandatory by 2025, the rapid increase of distributed generation is expected. Which means, we must prepare for an electricity-power accident and stable electricity supply. Also electricity charges have to be reduce and the grid-connected should be operated efficiently. The introduction of ESS is suggested as a solution, so the analysis of the load matching and grid interaction is required to optimize ESS design. This study analyzed the load matching and grid interaction by expected consumption behavior using actual data measured in one-minute intervals. The experiment was conducted in three nZEH with photovoltaic system, called all-electric houses. LCF (Load Cover Factor), SCF (Supply Cover Factor) and $f_{grid}$ (Grid Interaction Index) were evaluated as an analysis indicator. As a result, LCF, SCF and $f_{grid}$ of A house were 0.25, 0.23 and 0.27 respectively; That of B house were 0.23, 0.23, 0.19, and that of C were 0.20, 0.19, 0.27 respectively.

• 한국정보통신학회논문지
• /
• 제22권4호
• /
• pp.624-633
• /
• 2018

멀티미디어 강의시스템은 첨단 기술로 스마트해지고 있지만 마이크는 손에 들거나 신체에 부착하는 고전 방식에 여전히 의존하고 있다. 본 논문에서는 천정 부착형 배열 마이크를 제안하여 넓은 범위를 지원하면서 화자가 아무 장비를 착용하지 않고 자유롭게 이동이 가능함을 보였다. 제안된 시스템은 복잡한 빔 포밍 방식 대신에 이동통신의 셀(Cell)과 핸드 오버(Handover)를 적용하여 셀 간에 연속되는 마이크를 저가로 구현하였다. 음성에서 무성음 구간이 의사잡음(Pseudo Noise)과 유사한 특징을 이용하여 3개의 마이크에 지연-합의 다중경로 수신기를 연결하여 소프트 핸드오버를 제공하였다. 제안된 마이크 시스템은 강단 범위인 $6.3{\times}1.5m$ 영역에서 동작을 검증하였다. 실시간 처리를 위하여 상관기(Correlator)의 연산 범위를 82% 이상 줄였으며 출력 지연은 지연 적응 필터로 개선하였다.

• 한국정보처리학회논문지
• /
• 제4권11호
• /
• pp.2801-2811
• /
• 1997

본 논문에서는 화상회의 시스템에서 다양한 미디어의 동기화를 위해서 미디어 지연시간(delay time)의 편차를 분석하여 대기시간을 적용하여 동기화하는 방법을 제안한다. 또한 미디어 트래픽의 손실률과 대기시간을 이용하여 대기시간을 결정하는 데 중요한 외부변수의 값을 결정한다. 먼저 제안된 시스템은 회의를 시작하기 전에 더미 스트림을 발생시켜 지연지터의 편차를 구하여 네트워크 트래픽을 분석하여 미디어의 표현시간을 정의한다. 미디어 스트림이 표현되는 시간은 기준시간(basetime)＋논리 시간＋대기시간이 된다. 이 때 대기시간을 적절하게 늘이고 줄이기 위해서 대기시간 변경율과 표본단위를 이용하는데, 평가기준은 대기시간을 변경시키는 횟수, 평균 대기시간, 지연도착율, 평균 지연도착시간을 이용한다．

• 영어영문학
• /
• 제57권5호
• /
• pp.727-755
• /
• 2011

In this paper, I'll try to read Don Lee's Yellow intertextually with a more canonical text, Sherwood Anderson's Winesburg, Ohio, in order to see what kind of traditions and techniques Yellow references and/or rewrites as a way of tracking this production. Yellow's formal properties as a short story cycle are established through its use of particular conventions. For instance, Yellow follows the short story cycle model that includes the assemblage of recurring characters into one locale. Yellow's characters are all connected to and at some point located in the fictional small town of Rosarita Bay, California. The text form aligns it with established literary conventions and traditions and suggests the author's reliance upon or trust in those modes. Yellow's setting in a small town alludes to and has often been compared to Anderson's Winesburg, Ohio, which is perhaps one of the most well-known and extensively discussed short story cycles in American literature. Also following convention is Lee's construction of Rosarita Bay and the text's third person narrator as a member of that town. Both Rosarita Bay and the narrator become important figures through the related-tale nature of the text. The method of story-telling is similar to how the town Winesburg and its "seemingly sympathetic and non-overtly judgmental" narrator are operational in Anderson's text. In sum, Yellow is opportune for intertextual reading largely because it is a collection of stories that create a linked series.

• 한국항만경제학회지
• /
• 제27권1호
• /
• pp.247-262
• /
• 2011

본 논문은 광양항의 발전전략을 수립하기 위하여 SWOT/AHP분석을 실시하고자 한다. SWOT분석은 보통 전략수립단계에 있어서 내 외부 환경을 분석하기 위해서 사용된다. SWOT/AHP분석은 Kurttila et al(2000)이 SWOT분석의 유용성을 개선하기 위해 제안한 방법으로 SWOT분석의 결과는 단순히 SWOT그룹 내에 어떤 요인들이 있는가를 확인하는 것에 불과하다. 따라서 AHP분석과 결합함으로써 SWOT분석에서 도출된 요인들에 대한 상대적인 중요도를 평가하여 전략수립에 활용하는데 목적이 있다. 분석결과를 요약하면, SWOT그룹의 상대적 중요도는 기회(0.376), 강점(0.259), 위협(0.206), 약점(0.159) 순으로 나타났다. 다음으로 SWOT요인 별로 살펴보면, 강점요인의 상대적 중요도에서는 저렴한 화물처리비용(0.383), 우수한 항만입지(0.347), 광범위한 배후지(0.270) 순으로 나타났다. 약점요인의 상대적 중요도는 효율적인 통관시스템 미비(0.511), 복합운송 연계성 미비(0.315), 항만전문인력의 부족(0.173) 순으로 나타났다. 기회요인의 상대적 중요도는 각종 인프라 구축으로 수송체계 개선(0.461), 주변지역에 대한 연관산업단지 개발지속(0.326), 동북아지역의 물동량 증가추세(0.214) 순으로 나타났다. 위협요인의 상대적 중요도는 각종 인프라 구축으로 수송체계 개선(0.411), 주변항만과의 경쟁(0.400), 복합운송업체의 영세성(0.189) 순으로 나타났다. 평가대상이 되는 각 그룹별 세부요인들의 종합순위를 얻기 위하여 의사결정 항목들의 상대적 중요도를 종합화하였다. SWOT그룹별 세부속성요인들의 최종 중요도(가중치) 결과를 살펴보면, 기회요인 속하는 각종 인프라구축으로 인한 수송체계 개선(0.173), 주변지역에 대한 연관산업단지 개발지속(0.123)이 가장 높은 중요도를 보였고, 저렴한 화물처리비용, 우수한 항만입지, 항만운영의 융통성 결여, 주변항만과의 경쟁, 효율적 통관시스템 미비의 순으로 나타났다.

• 벤처창업연구
• /
• 제10권3호
• /
• pp.51-60
• /
• 2015

본 연구는 창업 활성화의 근원이라 할 수 있는 창업의지에 영향을 주는 요인들을 발굴하고 이들 간의 인과관계를 밝혀 보고자, 창업동기를 비롯한 성취욕구와 창업가정신과 같은 창업가적 심리특성을 살펴보았다. 다시 말해서, 창업동기의 매개역할을 중심으로 성취욕구 및 창업가정신이 창업의지에 미치는 영향관계를 고찰하였다. 이를 위하여 창업보육기관 입주기업의 창업자들로부터 회수한 설문지 181부를 실증 분석하였다. 분석결과, 첫째, 성취욕구와 창업가정신이 창업동기에 긍정적인 영향을 미침으로써, 이 두 변수가 창업동기의 선행변수인 것으로 나타났다. 둘째, 창업동기가 창업의지에 유의적인 영향을 줌으로써, 이 두 변수의 선 후행관계가 명확히 밝혀졌다. 셋째, 본 연구의 핵심이라 할 수 있는 성취욕구 및 창업가정신과 창업의지 간에 창업동기의 매개효과를 보였다. 다시 말해서, 창업동기가 성취욕구 및 창업가정신으로 하여금 창업의지를 더욱 강화시켜 줄 수 있는 매개역할을 하는 것으로 나타났다. 결국 창업의지를 높이기 위해서는 성취욕구, 창업가정신, 특히 창업동기와 같은 창업가적 심리특성을 강화시켜야만 한다. 이와 같은 본 연구결과를 바탕으로, 창업의지관련 이론적 시사점은 물론 실무적 시사점을 제공하고자 한다.