• 로봇학회논문지
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• 제6권3호
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• pp.230-236
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• 2011

In previous researches, the self-stability was studied for the spring-mass model and the two segment leg model. In these researches, it was presented that the spring-mass model has the self-stable region at relatively high speed running and the two segment leg model has the self-stable region at relatively low speed running. If the model was run in the self-stable region, the cost of transport is zero ideally. That is, actually, only the energy loss is needed to compensate for running. This means that the energy efficiency is high, running in the self-stable region. We want to have high energy efficiency at low and high speed running. So, in this paper, we propose the design direction of the three segment leg having the self-stable region at low and high speed running. And we prove the self-stable region of the three segment leg designed by the proposed design direction.

• 로봇학회논문지
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• 제13권2호
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• pp.86-91
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• 2018

This paper presents about design efforts of a human-sized quadruped robot leg for high energy efficiency, and verifications. One of the representative index of the energy efficiency is the Cost of Transport (COT), but increased in the energy or work done is not calculated in COT. In this reason, the input to the output energy efficiency should be also considered as a very important term. By designing the robot with customized motor housing, small rotational inertia, and low gear ratio to reduce friction, high energy efficiency was achieved. Squatting motion of one leg was performed and simulation results were compared to the experimental results for validation. The developed 50 kg robot can lift the weight up to 200 kg, and during squatting, it showed high energy efficiency. The robot showed 71% input to output energy efficiency in positive work. Peak current during squatting only appears to be 0.3 A.

• 기술사
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• 제45권5호
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• pp.26-35
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• 2012

Korea is now the 12th largest economy in the world, surpassing its annual trade in the amount of $1 trillion, and it has joined the socalled 20-50 Club, becoming one of the seven countries in the world with capita income of more than $20,000 with population of 50 million. However it ranked 24th of the Global competitiveness index evaluated by World Economic Forum based on the basic requirements including infrastructures, efficiency enhances, innovation and sophistication factors, etc. The extensive and efficient SOC infrastructures are critical for ensuring the global competitiveness of each country. Effective modes of SOC facilities including quality roads, railroads, ports, air transport, etc will be able to reduce the annual traffic congestion cost as well as macro economic logistics costs in Korea, thereby the global competitiveness can be strengthened in the global market.

• 유통과학연구
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• 제10권5호
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• pp.19-28
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• 2012

The study examines the performance and its relationship with capital structure and agency cost with respect to the industrial configurations and economic groups of Pakistan Economy. The study employs data set of 334 listed joint stock companies from the nonfinancial sectors for the period of 1999-2009 from cotton and textile, engineering, chemical, sugar, cement, fuel and energy, paper and board, transport and communication, and miscellaneous economic groups. Pooled data from the Panel data methodology has been applied to observe the significance of different performance measures through determinant of capital structure and agency costs with special focus on the leverage and cash flows as the direct determinant and interactive variables. The empirical test results using redundant variable tests demonstrate support for agency theory in the context of Pakistan's industrial configurations. The implications of the study point towards more investigations on the subject using industrial configurations as control and moderating variables.

• 한국철도학회논문집
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• 제9권1호
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• pp.95-101
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• 2006

Light rail transit system has many characteristics of better accessibility, frequency service, low construction cost, reduced air pollution and medium-capacity public transport etc. Light rail transit system as a urban transportation system has been growing worldwide since the late 20th century. More than 300 cities around the world have light railway systems. Many medium-size cities in domestic site is planning the construction of light railway. This paper describes the development strategies for the light rail transit industry.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2000년도 ITC-CSCC -1
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• pp.505-508
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• 2000

We discuss simulation results concerning the performance of the TCP protocol when running over high-speed HFC networks. Hybrid Fiber Coaxial are likely to provide fast and cost effective sup-port to a variety of applications including Video on demand, interactive computer games, and internet-type applications such as Webbrowsing, ftp, and telephony. Since most of these applications, use TCP as the transport later protocol, the key to their success largely depends on the effectiveness of the TCP protocol. In all simulation scenarios the TCP traffic is maxed with some background traffic whose level is taken as a variable parameter. Both the background traffic and TCP traffic are either unshaped, or shaped according to the GCRA algorithm. The effect of the background traffic on the TCP protocol performance is discussed varying the buffering capacity with nodes as well as the peak bit rate that each TCP connection is allowed to use.

• 한국항해항만학회지
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• 제33권9호
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• pp.615-621
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• 2009

Road and maritime transport which connecting main cities in the world is already fully saturated, and the loss cost caused by recent high oil prices is getting bigger. Transportation by inland waterway is rising as an alternative method of them. Concerning this, the GI Waterway is on construction to connect the Yellow sea and Seoul. Nevertheless, there are no existing aids to navigation around the area and no studies have been carried out for them. As the construction progresses, installation of proper aids to navigation should be considered and profound studies need to be carried out. This study focused on introduction of the cases and the systems of other countries inland waterway aids to navigation and suggested a suitable navigation aids system along the inland waterways in Korea and a way of installation for that system.

• 한국항해항만학회:학술대회논문집
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• 한국항해항만학회 2015년도 추계학술대회
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• pp.239-240
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• 2015

본 연구는 복합운송경로상 국제물류에 있어서 신규 운송경로가 추가되는 경우, 화주 및 포워더들의 기존 경로를 포함하여 운송경로 선택에 어떠한 영향을 미치는지에 대하여 비용과 시간 요인의 미치는 영향에 대해 연구하였다. 본 연구에서는 한국과 몽골간의 현재 있는 경로 및 10년후의 신규경로에 대하여 고찰하였으며, 이로서 신규노선에 대한 화주 및 포워더의 새로운 비즈니스 전략 검토가 예상된다.

• 경영과정보연구
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• 제24권
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• pp.155-185
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• 2008

This study tries to find out the resonable improvement method of the export logistics system for fresh agriculture products. Export logistics system improvement of fresh agriculture products rationalized the export network covering the export and import of fresh agriculture products from producers to end customers and realized cost reduction and profit maximization. We are also operating our very own comprehensive logistics system that maximizes customer satisfaction. Supporting the entire logistics process starting from the collection, unloading, sorting, packaging, customs clearing, and information up to comprehensive logistics services, the export logistics system of fresh agriculture products realized a comprehensive transport system that uses 12 feet cool container. We have successfully reduced logistics costs through efficient operation in the export logistics system of fresh agriculture products.

• 한국항만경제학회지
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• 제21권1호
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• pp.23-44
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• 2005

The port environment is rapidly changing in North-East Asia. Containerships are getting larger and faster and major shipping companies are converting to Hub & Spoke port networks on the transport systems. Therefore, the main ports in North-East Asia are intensively competing with each other for hub port. In terms of geopolitical position, locational conditions and external reputation of ports, Busan and Kwangyang ports have a comparative advantage in comparison with main ports in other countries. But in terms of weight of transshipment cargos in total container cargos, the quality of infrastructure in ports, the environment of logistics service and the cost of, using ports, Busan and Kwangyang ports have a comparative disadvantage. For the growth into hub port in North-East Asia, it is necessary that Busan and Kwangyang ports improve their weakness. Besides It is necessary to develope ports and hinterland quickly, offer uniformity of foreign investment laws and incentive systems.