• Journal of Advanced Marine Engineering and Technology
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• v.37 no.8
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• pp.977-983
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• 2013

Based on the consideration of the hourly patterns of the electricity power consumption, this study predicted the effectiveness of hybrid power generation system, which is composed with wind power generator and photovoltaic generator. And this case study is performed at Konrido, which is a affiliated island of Kyeongsangnam-do. As the results, it is obvious that it is not efficient to cover the whole electricity power consumption only with any single power generating system, because the hourly patterns of electricity power consumption, wind power generation and photovoltaic generation are quite different. And because the wind is being through almost 24 hours, it is also found out that wind power generating system with storage battery is the most efficient combination for this case study.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.40 no.2
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• pp.129-138
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• 2012

A MDO study of a midium-sized solar powered High Altitude Long Endurance (HALE) UAV has been performed, focused on energy balance. In the MDO process, Vortex Lattice Method(VLM) is employed for the aerodynamic modeling of the vehicle, of which structural weight is estimated with the modeling proposed by Cruz. Tail volume ratios have been set as constants, while the location of tail surfaces is determined from longitudinal static stability criterion. By balancing the available energy from solar cells, battery, and altitude, with the energy-requirement of the vehicle, the possibility of continuous flight over 24-hours has been investigated. The solar radiation level is set as that of summer at the latitude of $36^{\circ}$ north. During the daytime, the aircraft climbs using solar energy, accumulating potential energy, which supplements energy balance during the night. Optimizations have been sought in size of the vehicle, its weight distribution, and flight strategy.

• Journal of Digital Convergence
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• v.11 no.7
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• pp.141-148
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• 2013

Smart grid can two-way communication using ICT(Information & Communication Technology). Also, smart grid can supply to dynamic power that grafted to electric vehicle can activate to electric vehicle charging infrastructure and used to storage battery of home. Storage battery of home can resale to power provider. These electric vehicle charging infrastructure locate fixed on home, apartment, building, etc charging infrastructure that used fluid on user. If don't authentication for user of fluid user use to charging infrastructure, electric charging service can occurred to illegal use, electric charges and leakgage of electric information. In this paper, we propose smartcard and dynamic ID based user authentication scheme for used secure to electric vehicle service in smart grid environment.

• Journal of Digital Convergence
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• v.15 no.7
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• pp.41-53
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• 2017

This study focuses on the current state of Smart Grid policy in Japan and its problems while the interest in Smart Grid has been increasing since the March 2011 earthquake in East Japan. As a result of the analysis, Japan introduced the fixed price buying system of new and renewable energy in response to the power supply and demand problem caused by the 2011 earthquake in East Japan, and established a decentralized green electricity trading market in which electricity generated from new and renewable energy is traded Smart Grid-related projects were implemented as a solution to solve energy crisis and environmental problems at the same time. As a result, we achieved visible results such as suppressing peak power, reducing CO2 emissions, and securing stable supply and demand of energy using renewable energy sources. On the other hand, the improvement of current Smart Grid policy operation in Japan and the introduction of stabilization system of power system, promotion of international standards of domestic technology related to smart grid, and support for strengthening security of smart grid.

• Proceedings of the Korea Water Resources Association Conference
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• 2002.02a
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• pp.309-324
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• 2002

국내의 경우 관개용수의 대부분은 벼생육을 위한 논의 관개응수로 사용되고있다. 농업용수 이용은 약 150억㎥/year, 이는 하천유지수량을 제외한 전체 물이용량 237억㎥/year의 약 63%에 해당한다. 최근 물절약은 가장 중요한 사회, 경제적인 이슈 중의 하나로 인식되고 있다. 그러나, 국내의 경우 관개효율은 여전히 낮아 약 35%의 관개용수가 손실되는 것으로 추정되고있다. 비록 관개에서의 물절약이 시급한 문제이기는 하지만 용수손실 원인에 따른 손실량에 대한 정량적인 연구가 행해지지 않았었다. 손실 원인에 따른 손실량을 계측하기 위한 시험지구로 경기 평택의 이동지구를 선정하였다. 시험지구의 주수원공으로는 유역면적 9,440ha, 관개면적 2,027ha인 이동저수지이며 상류유역에 미산 및 용덕저수지가 위치하고 관개지구내에 원암 및 은산양수장이 있다. 시험지구의 계측시설은 강우량 계측을 위하여 자기강우계를 설치하였고 저수위, 하천수위 및 응배수로의 수위 측정을 위하여 수위계를 설치하였다. 강우계는 4개소에 설치되었으며 수위계는 26개소에 설치되었다 강우계는 지구내의 저수지 및 양수장 관리사 부근 4개소에 전도형 자기우량계를 설치하였다. 수위계 26개소 중에서 저수지의 저수위 계측지점이 3개소이며 하천수위 계측지점이 2개소 그리고 용배수로의 간선수로 시점부와 간지선 분기점 등의 주요지점에 21개소의 계측지점이 있다. 모든 계측지점의 계측기에는 자체 혹은 별도의 자료저장용 데이터로거가 부착되어 현장 계측자료를 저장하도록 설치 되어있다. 강우계는 전도형강우계(tipping bucket type)이며 수위계는 계측지점의 특징에 따라 여러종류의 수위계측기가 설치되었다 예를들어 초음파수위계(ultrasonic-wave type), 부표식수위계(float type) 그리고 압력식수위계(Pressure type)가 설치되어 있다. 현장 계측기의 전원은 한국전력 전원 혹은 태양전지 및 축전지를 사용하였다. 수위계측지점의 유량을 환산하기 위하여 계측지점의 단면조사와 유속측정을 통해서 수위-유량관계(rating curve)를 규명하였다. 시험지구의 관개효율 및 용수손실 규명 등에 관한 기본자료를 수집하기 위해서는 계측시스템의 운영은 장기간으로 지속 되어야 한다

• KEPCO Journal on Electric Power and Energy
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• v.2 no.1
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• pp.49-54
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• 2016

The large scaled lead-acid battery is widely used for efficient operation of the photovoltaic system in many islands. However, lithium-ion battery is now being introduced to mitigate the fluctuation of wind power and to replace lead-acid battery. Therefore, hybrid ESS (Energy Storage system) that combines lithium-ion battery with lead-acid battery is being required because lithium-ion battery is costly in present stage. Under this circumstance, this paper presents the optimal algorithm to create composition rate of hybrid ESS by considering fixed and variable costs in order to maximize advantage of each battery. With minimization of total cost including fixed and variable costs, the optimal composition rate can be calculated based on the various scenarios such as load variation, life cycle and cost trend. From simulation results, it is confirmed that the proposed algorithms are an effective tool to produce a optimal composition rate.

• Resources Recycling
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• v.28 no.4
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• pp.3-14
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• 2019

Lead is one of the common non-ferrous metals used in modern industry. The usage of lead continues to increase and has risen from 5 million tonnes per year worldwide in the 1970s to 11 million tonnes in the 2010s. In principle lead is virtually 100 % recyclable as an element without loss of quality. The recycling of lead scrap reduces the energy consumption and environmental burden, comparing to the primary metal production. Therefore production of secondary lead from scrap has been steadily growing and at present it meets approximately 60 % of usage worldwide. Lead scrap (mainly lead-acid battery) is smelted in primary and secondary smelter. Most secondary lead smelting were performed in a shaft-type furnace (blast furnace), rotary furnace and reverberatory furnace. The lead bullion is either cast into ingots and re-melted in refining kettles or refining is performed on the hot lead bullion immediately after production. This work provides an overview of the primary lead production and recycling process.

• Journal of the Korean Society of Marine Environment & Safety
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• v.29 no.2
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• pp.207-214
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• 2023

Ships emit significant amounts of air pollution. To reduce ship emissions, the government has implemented the Eco-Friendly Ship Act to improve the marine air environment, under which the use of eco-friendly ships that use eco-friendly energy as a power source encouraged and technologies to reduce marine pollution are developed. Therefore, the revision of relevant laws and systems such as inspection and facility standards for the safe operation of eco-friendly ships is urgently needed, especially those for fishing vessels, which account for the majority of domestic coastal vessels. This study defines the core equipment for the application of electric complex propulsion systems to fishing boats and presents a minimum safety standard plan for the adoption and dissemination of eco-friendly fishing boats.

• Journal of Preventive Medicine and Public Health
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• v.29 no.4 s.55
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• pp.733-746
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• 1996

To evaluate the follow-up management state and related factor of lead battery workers in periodic health examination as part of program of group occupational health service, author studied 293 workers with questionnaire on knowledge of results and follow-up management state and related factors, and compared the responses to their periodic health examination result charts. The results were as follows: 1. 252(86%) workers responsed that they had received the health examination result chart, but only 116(39.6%) workers responsed that they had been educated or explained about the results of health examination, and 11(57.9%) workers among 19 workers with non-occupational disease D, 101(44.3%) workers among 228 workers with non-occupational disease C, and 19(28.4%) workers among 67 workers with occupational disease C knew accurately their health examination results. 2. 78(24.8%) of the workers responsed that they had follow-up management, and contents of follow-up management were follow-up(36.6%), out-patient treatment (31%), change worksite(8.5%), temporary retirement(7.0%) and others(16.9%). 3. Most of the workers responsed that the health examination were necessary, but three-fourths of the workers responsed that the health examination had been superficial or that they didn't know. 4. In this study, follow-up management show significant association with only explanation or education about health examination result chart.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.13 no.2
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• pp.39-45
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• 1999

In case of field weakening region, torque is directly affected by flux. In this region, the flux reference is cIecreased inversely proportional to the rotor speed. As the flux is decreased, the magnetizing inductance is nonnally increased The increased magnetizing inductance limited voltage for controlling current In this paper, rreasuring q axis voltage in field weakening region, magnetizing inductance in flux calculating can be readjusted. Computer simulation and experiment results demostrate the efficacy of the prqx>sed rrethod. Proposed algorithm is expected to the application of the adjustable drive system in the spinning and weaving field. field.