• Proceedings of the KIPE Conference
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• 2016.07a
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• pp.287-288
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• 2016

기존 자가발전 운동기구의 경우, 가변저항을 사용하여 운동강도를 조절하기 때문에 Generator에서 생성된 에너지가 모두 소모되는 문제점이 있다. 또한 계통연계형 자가발전 운동기구의 경우에는 에너지 회수는 가능하지만 운동 강도 조절이 불가능한 단점이 존재한다. 따라서 본 논문에서는 계통연계를 통해 에너지 회수가 가능하고, 운동 강도 조절이 가능한 자가발전 운동기구용 DC/DC 컨버터를 제안한다. 제안회로는 가변저항을 사용하지 않고 입력임피던스를 통해 운동 강도를 조절하기 때문에 높은 에너지를 생성할 수 있고 계통연계를 통해 에너지 회수도 가능한 장점이 있다. 본 논문에서는 제안된 회로의 이론적 특성을 분석하고 모의실험을 통해 확인하였으며, 계통연계형 자가발전 운동기구에 적용하여 실험을 통해 우수성을 검증하였다.

• Journal of Korea Technology Innovation Society
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• v.15 no.1
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• pp.47-75
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• 2012

Basic research have contributed to technological growth or economic growth in U.S. Specially recent studies say that universities also contribute to economic development through scientific activities like science research, education, technology transfers. But we can not assure whether scientific knowledge was connected to real technology or economic performance, and it is difficult to figure out the effect of scientific output. "What is the exact performance of scientific knowledge?" It is still obscure. In this context, this paper analyzes characteristics of the linkage of science and technology. Data are U.S. R&D expenditure, scientific articles, citation of articles in U.S. patents by fields and sectors. As a result, university sector has the most weight of the linkage of science and technology. But, in relative connection rate analysis, industrial sector's is stronger than any other sectors. In the field analysis, linkage of science and technology is very strong in Chemistry, Physics, Biological sciences fields. And recently the linkage was increased in the fields of Computer science, Agricultural science, Engineering. Finally, this paper supports funding policy or estimation policy of government to product of scientific knowledge. University sector is still important because it has the most weight of the linkage. Scientific knowledge of industrial sector is also important. The connection rate of industrial science is the strongest in all sectors. And this research classify the R&D type by science fields. Considering the differences of science fields is needed to product science knowledge effectively.

• Journal of the Korean association of regional geographers
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• v.12 no.6
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• pp.693-703
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• 2006

Keeping the balance between exploration of new possibilities and exploitation of existing certainties in organizational innovation is getting its significance as business environments become more turbulent This paper focused on the relationship between two different types of innovation and network configuration. For this purpose, we conducted the empirical studies of 168 IT SMEs located in Gyeongbuk. For this analysis, we defined two innovation types as exploratory innovation and exploitative innovation. Also, we considered network scope and strength of tie as network configuration. The results showed that the exploratory innovation had sparse network of network scope and weak tie of strength. On the contrary the exploitative innovation had dense network and strong tie.

• Journal of Korean Society of Transportation
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• v.28 no.3
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• pp.85-98
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• 2010

As transit networks are becoming more multimodal, the concept of connectivity of transit networks becomes important. This study aims to develop a quantitative model for measuring the connectivity of multimodal transit networks. To that end, we select, as evaluation measures of a transit line, its length, capacity, and speed. We then define the connecting power of a transit line as the product of those measures. The degree centrality of a node, which is a widely used centrality measure in social network analysis, is employed with appropriate modifications suited for transit networks. Using the degree centrality of a transit stop and the connecting powers of transit lines serving the transit stop, we develop an index quantifying the level of connectivity of the transit stop. From the connectivity indexes of transit stops, we derive the connectivity index of a transit line as well as an area of a multimodal transit network. In addition, we present a method to evaluate the connectivity of a transfer center using the connectivity indexes of transit stops and passenger acceptance rate functions. A case study shows that the connectivity evaluation model developed in this study takes well into consideration characteristics of multimodal transit networks, adequately measures the connectivity of transit stops, lines, and areas, and furthermore can be used in determining the level of service of transfer centers.

• Journal of Korea Technology Innovation Society
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• v.13 no.4
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• pp.680-699
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• 2010

In this paper, we attempted to analysis and track dynamic properties of the interdisciplinary relationship between scientific research areas in energy field using bibliometric analysis. We created network maps with SCs (subject categories) defined from $WoS^{\circledR}$ (Web of Science, Thomson Scientific ISI, Philadelphia, USA) using co-occurrence analysis method in order to identify overall disciplines directly linked with energy fields and investigate the change of interaction between SCs as a function of time. From the results of this study, thermodynamics, fuels, chemistry/chemical engineering, and electrochemistry have differentiated into more specific disciplines while the strength of interaction with energy field gradually has increased. Meanwhile, "nuclear physics" was developed to "nuclear science & technology" toward applicable target sector and also the interaction of "environmental science" with "energy generation area" among various energy disciplines recently showed the radical increase as compared with the values of 4 years ago. Finally, through combinative reviews of today's energy policy established by South Korea government, this study will give a help for keeping up with national energy agenda meeting the diverse characteristics of academic disciplines of energy field. In addition, our results support that the use of such network analysis based on bibliometric analysis to discern shifts in academic R&D strategies and target sectors.

• Journal of the Korean Society for Railway
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• v.16 no.6
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• pp.503-509
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• 2013

Since the opening of KTX, the number of people coming to KTX stations to use KTX has steadily increased. Passengers have a variety of access modes between a KTX station and their origin/destination. But there is no way to confirm the level of connection strength. So this study examines various connection characteristic variables that can show the connectivity, and examines influencing relationships, and chooses variables that affect connectivity by using a KTX modal split. We will suggest connectivity estimation models between a KTX station and origin/destination based on the selected connected variables.

• Journal of Korean Tunnelling and Underground Space Association
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• v.13 no.4
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• pp.291-304
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• 2011

Recently concern for subsea tunnels is increasing, The effect of high water pressure can not be ignored in the case of a deep subsea tunnel. Reinforcement like grouting is necessary for the stability of such a subsea tunnel. In this study, therefore, it was investigated how the water barrier and shear strength increment resulted from grouting had an effect on the stability of a subsea tunnel. To this end, two-dimensional hydromechanical coupled analyses were performed for a sensitivity analysis in terms of different range, permeability coefficient, and cohesion of grouting reinforcement for the rock classes I, III, and V with respect to RMR system. The mutual relationship between strength increment and water pressure increased by barrier effect due to grouting was investigated by analyzing the numerical results.

• 한국경영정보학회:학술대회논문집
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• 2007.11a
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• pp.29-34
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• 2007

본 연구는 공급사슬관리를 도입하고 있는 우리나라 기업에서 제품특성과 공급사슬 형태의 연계, 공급사슬 형태와 채널파트너와의 연계가 어떻게 공급사슬 성과에 영향을 미치는지에 대한 연구이다. 제품은 수요패턴을 기준으로 기능적 제품과 혁신적 재품으로 나눌 수 있고 이에 적당한 공급사슬 형태는 효율적인 공급사슬과 시장반응적인 공급사슬로 나눌 수 있다. 또한 공급사슬의 형태는 lean supply, agile supply로 나눌 수 있으며 최근에는 동시에 이행되는 leagile supply가 제시되고 있다. 공급사슬관리에서 채널파트너의 강도가 공급사슬의 성과를 결정하게 되는데 이는 필연적으로 공급사슬의 형태별로 달리 나타날 수 밖에 없을 것이다. 이 연구를 통하여 오늘날 기업에서 다양하게 생산되는 제품특성별로 적당한 공급사슬 형태의 연계를 제시하게 될 것이며 특히 leagile인 경우 많은 전략적 시사점을 줄 것이다. 또한 공급사슬특성과 채널파트너 연계에 대하여 살펴봄으로써 공급사슬관리의 성공가능성을 더 높일수 있을 것이다.

• Journal of the Korean Geosynthetics Society
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• v.23 no.1
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• pp.49-60
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• 2024

Recently, the frequency and intensity of typhoon-induced wave loading are increasing due to changed marine environments such as climate change. In addition, frequent earthquakes are causing a lot of damage around the world, including in Japan, Chile, Haiti, China, and Indonesia. In Korea, damage from typhoons has also been increasing since the 2000s, and the frequency and intensity of earthquakes are also increasing. Korea is surrounded by sea on three sides, so typhoons can cause a lot of damage to coastal structures, and earthquakes also cause a lot of damage to coastal structures. As such, the frequency and intensity of typhoon-induced wave loading and earthquakes are increasing both domestically and internationally, but there is no research linking typhoons and earthquakes. Therefore, in this study, numerical analysis was performed for a total of four cases by linking typhoon waves and earthquakes to the caisson breakwater. Numerical analysis was performed by applying wave loads in Case 1 and seismic wave in Case 2, seismic wave after wave loads in Case 3, and wave loads after seismic wave in Case 4. As a result of the numerical analysis, it was confirmed that in Case 3 and Case 4, which linked a typhoon and earthquakes, the damage caused by each load increased compared to Case 1 and Case 2 because the load was applied while the existing ground strength was reduced. In addition, it was confirmed that the greatest damage occurred in Case 3, in which seismic wave were applied after the wave loads.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2010.04a
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• pp.729-732
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• 2010

본 논문에서는 이산 변수 최적화에 적합한 유전 알고리듬을 이용하여 복합재 적층 패치의 최적강도설계를 수행하였다. 기저판(substrate)와 접착제(adhesive), 그리고 복합재 적층 패치로 이루어진 구조물에서 패치의 강도를 효율적으로 구하기 위해서 응력 함수 기반의 해석적 방법을 도입하였다. 면외 방향의 응력 함수를 가정하여 가상 공액일의 법칙(complementary virtual work principle)에 적용하였으며, 복합재 패치의 자유 경계조건으로부터 면내 방향의 응력함수를 결정하였다. 응력 함수를 통하여 구한 층간 응력 값은 자유 경계 효과를 잘 나타내었고, 이를 이용하여 패치의 강도 해석을 수행하였다. 강도 해석 시, 복합재 패치의 파괴 기준은 면내 응력들에 대해서는 최대 응력 척도를 사용하였으며, 층간 응력들에 대해서는 quadratic delamination 척도를 사용하였다. 유전 알고리듬을 이용한 최적강도설계 과정에서는 임의의 염색체가 주어진 적층 구속 조건을 만족할 수 있게 수정(repairing)하는 과정을 도입하였다. 또한 다수의 전역해(global optima)를 효과적으로 찾기 위해서 multiple elitism 기법을 도입하였다. 응력 함수 기반의 강도 해석방법과 유전 알고리듬과의 연계를 통한 복합재 적층 패치의 강도최적설계 기법은 패치 구조물의 해석 및 설계에 있어서 효율적인 도구로서 사용할 수 있을 것이라 사료된다.