• 대한기계학회논문집B
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• 제37권2호
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• pp.181-186
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• 2013

농업용으로 사용되는 소형트랙터 개발의 최근 이슈는 친환경과 높은 연비이다. 소형 트랙터는 비닐 하우스 등 실내에서 작업이 가능하도록 설계 되므로 최근 전기 트랙터에 대한 수요가 증가하고 있다. 그러나 전기트랙터는 배터리 등 전기에너지 저장장치의 용량 및 크기공간의 제약으로 충분한 작업시간과 성능 확보에 한계가 존재한다. 따라서 최근 전기 트랙터와 내연기관 트랙터의 특징을 결합한 플러그인 하이브리드 트랙터에 대한 개발이 진행 중이다. 트랙터는 기본 주행 능력외에 PTO 를 통한 여러 작업을 수행 할 수 있어야 하며, 플러그인 하이브리드 트랙터에서는 각각의 작업에 대한 주행전략이 필요하다. 본 연구에서는 트랙터의 작업 모드를 개발하고 그에 대한 각 작업의 작업시간 능력 등을 확인하였다.

• Strategy21
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• 통권37호
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• pp.144-176
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• 2015

In September 2013, President Park Geun-hye announced her controversial "Look North" policy, of which the most salient aspect is the "Eurasia Initiative". This comprises various proposals designed to overcome existing constraints by developing new markets and creating new economic partners in continental areas from which South Korea has been alienated since the end of World War II, and this dovetails nicely with China's One Belt, One Road Initiative. The concepts of the "Silk Road Rail Express (SRX)" and the "East Sea Rim Maritime Community (ESRMC)" have also been discussed. SRX is at present a purely symbolic railroad project intended to encourage individual, cultural, trade and diplomatic exchanges. ESRMC is a model for establishing an ad hoc community to promote regional economic cooperation around the East Sea. President Park's Eurasia Initiative will provide South Korean investment for the Northeast to complement Russian plans, like the "Northern Energy Road" being built by Gazprom, and Chinese plans, like the Chang-Ji-Tu Development Plan for the North Korean port of Rajin. China's trade, as well as its energy and food supplies, pass through the Strait of Malacca and the Indian Ocean, and are thus vulnerable to interdiction by India or the US. China is therefore trying to reduce its exposure geopolitical risk by establishing a network of corridors between the Belt and the Road to provide alternative paths. The "China-Pakistan Economic Corridor" and the "China-Myanmar Economic Corridor" provide such connections, and South Korea hopes that SRX and ESRMC can become part of a "China-South Korea Economic Corridor". This concept could do much to revitalize the underdeveloped northern provinces of China and Russia's Far East, not to mention North Korea. By linking up the Trans-Siberian Railway, the Trans-China Railway, the Trans-Mongolian Railway and the Trans-Korean Railway all these Asian countries will be connected to one another, and ultimately to Europe. An interim connection between China and South Korea using a rail-ferry has also been proposed.

• Journal of Contemporary Eastern Asia
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• 제19권1호
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• pp.59-83
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• 2020

This paper examines the actions and the factors driving those actions to reduce energy consumption and enhance energy efficiency taken by United States cities. While not much empirical evidence is available on why governments pursue practical sustainability actions, we attempt to shed more light on this important topic by empirically identifying factors that contribute to concrete actions toward sustainability policies. We adopt political market theory as a basic theoretical framework with policy-making applied to city energy consumption. Using the 2010 ICMA (local government sustainability policies and program) data, this study expands the focus of analyses to evaluate the effect of the form of government on energy consumption and energy efficiency by using multiple regression analysis. The findings show that at the city level, the mayor-council form of government are negatively associated with governments' efforts to reduce energy consumption. However, cities with at-large elections and municipal ownership are more likely to adopt sustainability actions. We also find that a large-scale economy has significant effects on the effort to reduce city energy consumption and improve energy efficiency. This shows that environmental policies are directly connected to locally relevant affairs, including housing, energy use, green transportation, and water. Thus, local level administrators could take an executive role to protect the environment, encourage the development of alternative energy, and reduce the use of fossil fuel and coal energy. These efforts can lead to important environmental ramifications and relevant actions by municipal governments.

• 방사선산업학회지
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• 제7권1호
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• pp.45-49
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• 2013

In tissue engineering application, a fibrous structure of scaffolds has been issued as an alternative system to regulate cell survival and tissue regeneration, and electrospinning technique has been popularly used to generate fibrous meshes or sheets mimicking the structure of native extracellular matrix (ECM). However, recent strategy in the scaffold development is expanded to provide the structural property as well as a biological property of native ECM, a variety of surface modification techniques have been used to introduce biological property. In this study, we developed biomimetic poly(L-lactide-co-${\varepsilon}$-caprolactone) (PLCL) nano- and micro-fibrous scaffolds as a unique platform with structural and biological properties with native ECM using electrospinning method and gamma-ray irradiation. Surface morphology of the scaffolds was observed by scanning electron microscopy, and alteration of surface property was evaluated with toluidine blue O staining, water contact angle measurement and ATR-FTIR analysis.

• KIEAE Journal
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• 제14권1호
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• pp.31-38
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• 2014

Recently, the coverage of urban forests has been rapidly decreasing as the cities are created and expanding. Consequently, there arise urban problems such as heat island effect, urban flooding, urban desertification and so on. In this context, green roof systems is considered to be an efficient alternative to deal with these problems. However, it is difficult to apply green roof to new buildings since the majority of the buildings in cities are already constructed and the demand for new building constructions is not high enough. Therefore, it should be considered to apply green roof system to existing buildings for resolving various problems. This study evaluates heating and cooling energy consumption based on the combination of passive design factors such as wall, roof, window insulation in addition to a green roof system applied to an existing house by using an energy simulation program. Total 8 potential improvement cases are developed. Each case is applied to the same house with different insulation standard for simulations. Through the analysis of the simulated cases with the chosen test house, it is confirmed that heating energy consumption decreases as improvement cases are applied, but cooling energy consumption is relatively not much affected by each improvement case. In addition, when each improvement case is applied to already highly insulated house, the effect of thermal energy improvement decreases while the same improvement that is applied to the case with low insulated house tends to yield higher improvement rate.

• 한국산업정보학회논문지
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• 제29권3호
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• pp.67-77
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• 2024

공장의 에너지 효율을 높이는 방안 중 공정 스케줄링은 제조 공정에서 자원을 최적으로 할당하여 제품의 생산 계획을 수립하는 활동이다. 그러나 야간 근로가 불가피한 경우에는 이러한 전략이 효과적으로 적용되지 않을 수 있다. 또한, 생산 요구량의 지속적인 변화로 인해 실제 공장에서의 적용에 어려움이 있다. 최근에는 전기자동차의 보급이 급증함에 따라 전기자동차 배터리를 에너지 저장 시스템으로 활용하는 기술이 주목을 받고 있다. 이러한 배터리를 활용한 기술은 공장 에너지 관리를 위한 대안이 될 수 있다. 본 논문에서는 전기자동차 배터리를 활용한 공장 에너지 관리 방안을 제안한다. 제안된 방안은 전기자동차 배터리 충전 상태 및 TOU(Time-of-use)를 고려하여 PSCAD/EMTDC 소프트웨어에서 분석된다. 제안된 방안은 예측된 전력 사용량과 TOU를 고려하여 수립된 공정 스케줄링과 비교 분석된다. 결과적으로 공정 스케줄링은 하루에 4,152원, 제안된 방안은 7,286원의 전기 요금을 절감하였다. 본 논문을 통해 공장 에너지 관리를 위해 전기자동차 배터리 활용 가능성을 확인할 수 있었다.

• 반도체디스플레이기술학회지
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• 제21권3호
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• pp.114-118
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• 2022

The stabilized all-solid-state battery structure indicate a fundamental alternative to the development of next-generation energy storage devices. Existing liquid electrolyte structures severely limit battery stability, creating safety concerns due to the growth of Li dendrites during rapid charge/discharge cycles. In this study, a low-dimensional graphene quantum dot layer structure was applied to demonstrate stable operating characteristics based on Li+ ion conductivity and excellent electrochemical performance. Transmission electron microscopy analysis was performed to elucidate the microstructure at the interface. The low-dimensional structure of GQD-based solid electrolytes has provided an important strategy for stable scalable solid-state lithium battery applications at room temperature. This study indicates that the low-dimensional carbon structure of Li-GQDs can be an effective approach for the stabilization of solid-state Li matrix architectures.

• JSTS:Journal of Semiconductor Technology and Science
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• 제16권4호
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• pp.451-462
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• 2016

Photovoltaic energy conversion becomes main focus of many researches due to its promising potential as source for future electricity and has many advantages than the other alternative energy sources like wind, solar, ocean, biomass, geothermal etc. In Photovoltaic power generation multilevel inverters play a vital role in power conversion. The three different topologies, diode-clamped (neutral-point clamped) inverter, capacitor-clamped (flying capacitor) inverter and cascaded h-bridge multilevel inverter are widely used in these multilevel inverters. Among the three topologies, cascaded h-bridge multilevel inverter is more suitable for photovoltaic applications since each pv array can act as a separate dc source for each h-bridge module. This paper presents a single phase Cascaded H-bridge five level inverter for grid-connected photovoltaic application using sinusoidal pulse width modulation technique. This inverter output voltage waveform reduces the harmonics in the generated current and the filtering effort at the input. The control strategy allows the independent control of each dc-link voltages and tracks the maximum power point of PV strings. This topology can inject to the grid sinusoidal input currents with unity power factor and achieves low harmonic distortion. A PID control algorithm is implemented in Arm Processor LPC2148. The validity of the proposed inverter is verified through simulation and is implemented in a single phase 100W prototype. The results of hardware are compared with simulation results. The proposed system offers improved performance over conventional three level inverter in terms of THD.

• 한국지진공학회:학술대회논문집
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• 한국지진공학회 1998년도 추계 학술발표회 논문집 Proceedings of EESK Conference-Spring 1998
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• pp.144-153
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• 1998

Base isolation is an innovative design strategy that provides a practical alternative for the seismic design of structures. Base isolators, mainly employed to isolate large structures subjected to earthquake ground excitations and to rehabilitate structures damaged by past earthquakes, deflect and absorb the seismic energy horizontally transmitted to the structures. This study demonstrates that the base isolation system may offer effective performance for bridges during severe seismic events through shaking table tests. Two base isolation system using laminated rubber bearings with and without hydraulic dampers are tested. The test results strongly show that the laminated rubber bearings cause the natural period of the bridge structure increased considerably, which results in the deck acceleration and the shear forces on the piers reduced significantly. The results also demonstrate that the hydraulic dampers enhance the system's capacity in dissipating energy to reduce the relative displacement between the bridge deck and the pier.

• 한국분무공학회지
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• 제19권3호
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• pp.115-122
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• 2014

As a demand for an automobile increases, air pollution and a problem of the energy resources come to the fore in the world. Consequently, governments of every country established ordinances for green-house gas reduction and improvement of air pollution problem. Especially, as international oil price increases, engine using clean energy are being developed competitively with alternative transportation energy sources development policy as the center. Bio ethanol, one of the renewable energy produced from biomass, gained spotlight for transportation energy sources. Studies are in progress to improve fuel supply methods and combustion methods which are key features, one of the engine technologies. DI(Direct Injection), which can reduce fuel consumption rate by injecting fuel directly into the cylinder, is being studied for Green-house gas reduction and fuel economy enhancement at SI(Spark Ignition). GDI(Galoine Direct Injection) has an advantage to meet the regulations for fuel efficiency and $CO_2$ emissions. However it produces increased number of ultrafine particles, that yet received attention in the existing port-injection system, and NOX. As fuel is injected into the cylinder with high-pressure, a proper injection strategy is required by characteristics of a fuel. Especially, when alcohol type fuel is considered. In this study, we tried to get a base data bio-ethanol mixture in GDI, and combustion for optimization. We set fuel mixture rate and fuel injection pressure as parameters and took a picture with a high speed camera after gasoline-ethanol mixture fuel was injected into a constant volume combustion chamber. We figured out spraying characteristic according to parameters. Also, we determine combustion characteristics by measuring emissions and analyzing combustion.