• 한국항해항만학회지
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• 제30권4호
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• pp.295-302
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• 2006

This study is to integratedly examine coastal management policy and marine tourism development project for Korean coasts, especially for the South Sea of high development pressure, presenting sustainable tourism development policies for the future. To do so, it is examined central government-level coastal development projects set up by the Ministry of Culture and Tourism, the Ministry of Maritime Affairs and Fisheries and the Ministry cf Construction and Transportation, setting the direction of south coastal management and tourism development at a level of national territory planning. The problems of coastal management first and then the problems of the South Coast Tourism Belt Project are analyzed in order to present political and administrative alternatives. To overcome such problems and make Korea a marine tourism base in East Asia, there is a need for re-recognition of the value of the project and its continuous push through cooperation between central and local governments. Also, under the presupposition of consensus building among local people and the sustainable development of environments, there should be are-recognition that the future cf Korean marine tourism in the 21st-century and the success of an inverted $\pi-axis$ national development depend on the South coastal Tourism Belt Development Project.

• Electronic Materials Letters
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• 제14권6호
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• pp.725-732
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• 2018

The thermoelectric and transport properties of Ti-doped FeVSb half-Heusler alloys were studied in this study. $FeV_{1-x}Ti_xSb$ (0.1 < x < 0.5) half-Heusler alloys were synthesized by mechanical alloying process and subsequent vacuum hot pressing. After vacuum hot pressing, a near singe phase with a small fraction of second phase was obtained in this experiment. Investigation of microstructure revealed that both grain and particle sizes were decreased on doping which would influence on thermal conductivity. No foreign elements pick up from the vial was seen during milling process. Thermoelectric properties were investigated as a function of temperature and doping level. The absolute value of Seebeck coefficient showed transition from negative to positive with increasing doping concentrations ($x{\geq}0.3$). Electrical conductivity, Seebeck coefficient and power factor increased with the increasing amount of Ti contents. The lattice thermal conductivity decreased considerably, possibly due to the mass disorder and grain boundary scattering. All of these turned out to increase in power factor significantly. As a result, the thermoelectric figure of merit increased comprehensively with Ti doping for this experiment, resulting in maximum thermoelectric figure of merit for $FeV_{0.7}Ti_{0.3}Sb$ at 658 K.

• 한국재료학회지
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• 제31권8호
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• pp.445-449
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• 2021

Zintl compound Mg₃Sb₂ is a promising candidate for efficient thermoelectric material due to its small band gap energy and characteristic electron-crystal phonon-glass behavior. Furthermore, this compound enables fine tuning of carrier concentration via chemical doping for optimizing thermoelectric performance. In this study, nominal compositions of Mg_3.8Sb_2-xTe_x (0 ≤ x ≤ 0.03) are synthesized through controlled melting and subsequent vacuum hot pressing method. X-ray diffraction (XRD) and scanning electron microscopy (SEM) are carried out to investigate phase development and surface morphology during the process. It should be noted that 16 at. % of excessive Mg must be added to the system to compensate for the loss of Mg during melting process. Herein, thermoelectric properties such as Seebeck coefficient, electrical conductivity, and thermal conductivity are evaluated from low to high temperature regimes. The results show that Te substitution at Sb sites effectively tunes the majority carriers from holes to electrons, resulting in a transition from p to n-type. At 873 K, a peak ZT value of 0.27 is found for the specimen Mg_3.8Sb_1.99Te_0.01, indicating an improved ZT value over the intrinsic value.

• 한국재료학회지
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• 제32권6호
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• pp.287-292
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• 2022

Magnesium-antimonide is a well-known zintl phase thermoelectric material with low band gap energy, earth-abundance and characteristic electron-crystal phonon-glass properties. The nominal composition Mg_3.8-xZn_xSb₂ (0.00 ≤ x ≤ 0.02) was synthesized by controlled melting and subsequent vacuum hot pressing method. To investigate phase development and surface morphology during the process, X-ray diffraction (XRD) and scanning electron microscopy (SEM) were carried out. It should be noted that an additional 16 at. % Mg must be added to the system to compensate for Mg loss during the melting process. This study evaluated the thermoelectric properties of the material in terms of Seebeck coefficient, electrical conductivity and thermal conductivity from the low to high temperature regime. The results demonstrated that substituting Zn at Mg sites increased electrical conductivity without significantly affecting the Seebeck coefficient. The maximal dimensionless figure of merit achieved was 0.30 for x = 0.01 at 855 K which is 30% greater than the intrinsic value. Electronic flow properties were also evaluated and discussed to explain the carrier transport mechanism involved in the thermoelectric properties of this alloy system.

• 한국미생물·생명공학회지
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• 제36권1호
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• pp.1-5
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• 2008

Negative environmental consequences of fossil fuels and the concerns about their soaring prices have spurred the search for alternative energy sources. While other alternative energies-like solar, wind, geothermal, hydroelectric, and tidal-offer viable options for electricity generation, around 40% of total energy consumption requires liquid fuels like gasoline or diesel fuel. This is where bio-energy/biofuels is especially attractive, where they can serve as a practical alternative to oil. The production of liquid biofuels for transportation will depend upon a stable supply of large amount of inexpensive cellulosic biomass obtained on a sustainable basis. This paper reviewed development status of transportation bio-energy for vehicles, technical barriers to the production of cellulosic ethanol, and the global future of bio-diesel and ethanol production.

• 대한안전경영과학회지
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• 제12권4호
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• pp.175-181
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• 2010

The government have plans to improve the railway transport capacity and transport hub for the sustainable national transport and logistics system. Specially, there are much efforts to improve transportation capacity such as high speed transportation of rail freight, enlargement of BT train, development of double stack train, etc. between railway transport hubs. If the transport capacity between railway logistics hubs is increased as planned, we must increase the handling capacity of railway hub terminals. But there are limits to enlarge the terminal infrastructure because of investment scale, location circumstances and urban development plans. To ensure the capacity, with the minimum required enlargement of infrastructure, it is necessary to extremely increase the efficiency of terminal operations. For improving the efficiency, we have to introduce the efficient terminal operation systems based on u-IT and operation optimize technologies. In this paper, we analyse the issues and problems of railway terminals(including ICD) and suggest the concept of intelligent railway terminal and the construction components of technology.

• 대한안전경영과학회지
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• 제12권3호
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• pp.315-320
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• 2010

Recently, there are environmental issues for sustainable transportation system to pursue the energy-efficient and environment-friendly public urban transit. These transportation system needs to offer demand-oriented high-quality service being on the same level with cab service for urban space. PRT(Personal Rapid Transit), small track-guided vehicle, is repeatedly mentioned as a possible alternative for the new urban public transportion system, but but there are not many researches on the operational optimal routing for PRT network. In this paper, the concept of PRT and general optimal routing methods are reviewed. And we suggest the optimal routing method for city-wide PRT network with multi-vehicles and stations, junctions and directional arcs. Futher research directions for PRT routing are presented.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2009년도 춘계학술대회 논문집 에너지변화시스템부문
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• pp.195-197
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• 2009

The role of environment-friendly and energy-efficient rail transportation is on the rise as a "sustainable transportation means" to cope with environmental changes that are major concerns around the world. Along with the environmental problems, the CO2 inhibition issue became critical for mankind to prepare global warming and high oil prices. It has come to a point where an alternate means are needed to revitalize plans including renewable energy, bicycle utilization, and prepare new solutions for decreasing number of cars within the city The personal rapid Transit(PRT) is the revolutionary future transportation means that can replace cars to deal with ever-increasing traffic congestions, vehicles, and environmental/energy problems. Expected as an efficient means, technology development has already taken place in developed countries such as U.S., England, and Germany. To meet the future demands, PRT installation around the nation's new and existing towns is being examined to produce important factors. The factors are produced for examining the availability of system requirements during design and construction practice.

• 전력전자학회논문지
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• 제27권4호
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• pp.356-366
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• 2022

This paper presents a mode transition method that applies frequency compensation technique of an LLC resonant converter for stable mode transition. LLC resonant converters used in various applications require high efficiency and high power density. However, because of circuit property, a wider voltage gain range equates to a greater circuit loss, so maintaining high efficiency at all voltage gain ranges is difficult. In this case, full bridge-half bridge mode transition method can be used, which maintains high efficiency even in a wide voltage gain range. However, this method causes damage to the circuit through overcurrent by the mode transition. This study analyzes the cause of the problem and proposes a mode transition method that applies frequency compensation technique to solve the problem. The proposed method verifies the stable transition through simulation analysis and experimental results.

• 대한교통학회지
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• 제36권1호
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• pp.1-12
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• 2018

본 연구는 교통온실가스 감축목표 설정 및 효과적 이행계획 수립에 기여하기 위한 교통온실가스 감축정책의 정량적 효과분석 방법론 정립을 목적으로 한다. 본 연구는 실제 교통 배출 자료에 근거한 교통수단별 온실가스 배출 원단위 추정모형을 포함하여, 수단효용함수와 수요추정모형 등을 활용하고 있다. 연구결과, 전기차 등 온실가스 감축정책 효과는 지역과 대상차종 등에 따라 다양하게 도출될 수 있으며, 저예산 정책인 에코드라이브 활성화 정책은 높은 온실가스 감축효과를 기대할 수 있는 것으로 확인되었다. 또한 자동차 배출개선 정책 뿐 아니라 대중교통 이용활성화 정책도 높은 온실가스 감축효과를 기대할 수 있으며, 본 연구는 이러한 사실을 정량적으로 확인하고 있다. 본 연구결과는 신기후체제 대응을 위한 국가 및 지자체의 온실가스 감축정책 평가에 유용하게 활용될 수 있을 것으로 기대된다.