• 한국신재생에너지학회:학술대회논문집
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• 2008.05a
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• pp.416-418
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• 2008

Dye-sensitized solar cell using transparent conducting oxide as electrode has large resistance such as surface resistance, charge transportation impedance in counter electrode and electrolyte, impedance between each interface. Among that resistances, surface resistance of transparent conducting oxide is relatively large. So the change of transparency has a large effect on internal resistance of dye-sensitized solar cell. Consequently, that change cause to increase or decrease the conversion efficiency. We tried to reduce the surface resistance by laser-scribing. The active area is seperated from total transparent conducting oxide by Nd:YAG laser-scribing. As a result, we achieved the improvement of efficiency about 7% and 11% in case of $0.25cm^2$ and $1.00cm^2$ dye-sensitized solar cells.

• Proceedings of the IEEK Conference
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• 2007.07a
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• pp.63-64
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• 2007

The Underwater Wireless Sensor Networks (UWSN) consists of sensor nodes equipped with limited sensing coverages, energy resources and communication capacity. Hence, the deployment and movement algorithm is a key issue that needs to be organized in order to improve the sensing efficiency of the networks. In this paper, we use a Queen problem and Knapsack problem to prevent the reiteration phenomenon of sensors, to guarantee improvement sensing coverage and efficiency in the 3D UWSN.

• KIEAE Journal
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• v.15 no.3
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• pp.21-28
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• 2015

Purpose: In this study, we analyzed the energy performance levels and high-performance technology trends through the case studies of foreign high-performance buildings. Method: Buildings built within 10 years were selected for the analysis of recent trends. we analyzed the buildings of U.S.A, Germany and Japan using LEED certified buildings, Passive House certified buildings and CASBEE certified buildings database for the case study of foreign high-performance buildings. A total of 20 high-performance buildings including 14 cases in U.S.A, 4 cases in Germany and 4 cases in Japan were selected. Annual energy consumption levels for 20 high-performance buildings were collected with the actual energy consumption data or data from simulation programs officially recognized by DOE. Annual energy consumption were compared with the energy performance standard of the office buildings in the CBECS database, ASHRAE Standard 90.1-2004 and Building Energy Efficiency Rating System in Korea. Result: The order of the green strategies applied in the main categories are Renewable Energy(63%), Indoor Environment Control(51%), Envelope Improvement(44%) and HVAC System & Control(28%). Specified strategies most widely used in the sub-categories are high-performance Insulation (70%), High Efficiency Heating, Cooling Source Equipment(85%), Photovoltaic&Solar Thermal(80%) and Daylighting(80%).

• Journal of Energy Engineering
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• v.23 no.4
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• pp.189-195
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• 2014

The use of solar energy among renewable energy tends to increase because of its infinity and cleanness of resources. Even though the consumption rate of solar energy in our country is still low, however, in recent years, the research for solar energy have been widely conducted due to policy support of government. This study was performed to investigate the efficiency of heat collection using solar collector with single evacuated tube-type. As the results, the temperature of radiation fin for solar collector with single evacuated tube-type was lower in spite of high temperature of heat pipe compared that of double evacuated tube-type. In order to increase the efficiency of heat collection, it was confirmed that the loss of heat collection due to contact resistance as well as performance improvement for solar collector should be decreased.

• Journal of the Korean Society of Safety
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• v.15 no.3
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• pp.66-70
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• 2000

In order to cope with environmental problems caused by harmful gases emitted from various industrial sources, a new technology which employs discharge plasma formed in ordinary atmospheric pressure has been intensively investigated in many industrialized nations. Although a plenty of useful outcomes and suggestions have been made public by scientists in this field, few commercial products which effectively decompose pollutant gases have appeared as yet. This is partly because that the energy efficiency of a most effective plasma reactor has not reached a satisfactory level in comparison with those of devices using conventional technologies. In an attempt to solve the problem mentioned above, we noticed to combine heterogeneous electrical discharges. This concepts is based on that each plasma reactor has its specific spatial region in which chemical reaction are active and by electrically affected with another reactor of different type, the activated region would increase - which may lead to cutting down the energy consumption. To prove this concept experimentally, two different discharge equipments, a plane ceramic-based surface discharge electrode and a corona electrode with tungsten needle may, are selected and combined to fabricate a hybrid plasma reactor. The results are summarized as follows; (1) Ozone concentration generated in the plasma region drastically increases when the positive corona discharge is added to the surface discharge. The rate of increase of ozone depends on the frequency of the surface discharge. The negative corona, however, does not contribute to the improvement of the ozone generation. (2) NO(nitrogen monoxide) decomposition rate also improves by simultaneously applying the surface and the positive corona discharges. The effect of the corona superposition is more evident when the level of the surface discharge is moderate. (3) By adjusting the corona level, the net energy efficiency during NO decomposition improves in comparison with the simple surface discharge reactor.

• Journal of Electrochemical Science and Technology
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• v.12 no.3
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• pp.330-338
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• 2021

An integral electrode-bipolar plate assembly, which is composed of electrode, conductive adhesive film (CAF) and bipolar plate, has been developed and evaluated for application with a vanadium redox flow battery (VRB) to decrease contact resistance between electrode and bipolar plate. The CAF, made of EVA (ethylene-vinyl-acetate) material with carbon black or CNT (Carbon Nano Tube), is applied between the electrode and the bipolar plate to enable an integral assembly by adhesion. In order to evaluate the integral assembly of VRB by adhesive film, the resistivity of integral assembly and the performance of single cell were investigated. Thus, it was verified that the integral assembly is applicable to redox flow battery. Through resistance and contact resistance of bare EVA and CAF films on bipolar plate were changed. Among the adhesive films, CAF film coated with carbon black showed the lowest value in through resistance, and CAF film coated with CNT showed the lowest value in contact resistance, respectively. The efficiency of VRB single cell was improved by applying CAF films coated with carbon black and CNT, resulting in the reduced overvoltage in charging process. Therefore, the energy efficiency of both CAF films, about 84%, were improved than that of blank cell, about 79.5 % under current density at 40 mA cm^-2. The energy efficiency of the two cells were similar, but carbon black coated CAF improved the coulomb efficiency and CNT coated CAF improved the voltage efficiency, respectively.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.23 no.1
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• pp.100-108
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• 2009

Due to rapid economic growth, the usage of residential cooling electrical appliances such as air conditioners and refrigerators has increased dramatically for the last decades. In other to reduce its energy consumption, the authorities have applied energy efficiency standards for principal appliances, including air conditioners. and then it can anticipate environmental effects. In this paper, it presents the actual procedure to analyze the effects for the decline in the $CO_2$ emissions and its methodology for the efficiency improvement of the air conditioner that takes a great portion of the summer power uses.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2010.06a
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• pp.33-33
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• 2010

Electrical properties of organic light-emitting diodes (OLEDs) were simulated by S.co's program. The OLEDs have stable operating parameters, high luminance, and high efficiency in simulation. The AF stands for amorphous fluoropolymer in simulation, and it was used as a hole-injection layer. In the five structure of OLEDs, an AF layer is sandwiched between the hole-transport layer and the ITO layer to increase the external quantum efficiency. By considering organic light-emitting diodes using an optimal energy gap of AF, it could contribute to the improvement of the efficiency of the device in the simulation.

• Journal of the Society of Naval Architects of Korea
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• v.59 no.6
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• pp.372-384
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• 2022

Total shipping accounts for 2.9 % of the annual average percentage of global anthropogenic GHG emissions. The International Maritime Organization implements EEDI (Energy Efficiency Design Index), Energy Efficiency eXisting-ship Index (EEXI), and Carbon Intensity Indicator (CII) as regulatory frameworks for shipping decarbonization. The Republic of Korea has enforced the Act on Development and Popularization of Greenship from 2020 and publicly announced the 1st national plan which was named 『2030 Greenship-K Promotion Strategy』 for the activation of a greenship market. The Greenship Certification Scheme is going on for the sustainability of Korean shipbuilding and shipping industries, to secure clean maritime environments, as well as to contribute to the national economy. Greenship Certification guarantees the credit of such eco-friendly technologies and products for shipping. The certification is going to be the basis of industrial competitiveness in coastal and international shipping. This study investigates an existing certification process, identifies the limitations, and proposes the process improved with several case studies. The improved certification scheme may have rationality for Net-zero with regard to climate alignment.

• Environmental and Resource Economics Review
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• v.18 no.4
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• pp.557-586
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• 2009

Although energy demand management policy attracts attention internationally and domestically, the importance of local government in this policy is not so much as central government. But local government can do a role with regard to this policy because it is close to energy consumers not like central government. So local energy plan should be based on the understanding local energy consumption characteristics to activate local energy demand management policy. This paper tries to analyze energy characteristics of 16 local governments by decomposing energy consumption into population, production and intensity factors. The result of index decomposition analysis shows that energy intensity improvement has offset the increase of energy consumption caused by economic growth in the metropolitan cities, while it couldn't offset in the other provinces because of industrialization based on the manufacturing. In conclusion, this paper suggests that it will be necessary to switch to low energy society by carrying out concrete energy efficiency improvement projects in the metropolitan cities while it will be helpful to make a local development plan for low energy intensive industrialization in the other provinces.