• Annual Conference of KIPS
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• 2012.04a
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• pp.884-887
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• 2012

무선 센서 네트워크 기술은 상시적으로 물리정보를 획득할 수 있기 때문에 광범위한 응용분야에서 수요가 증가하고 있다. 또한 무선 센서 네트워크에 적용되는 무선 센서 시스템은 일반적으로 배터리를 장착하여 회로에 전력을 공급해주는 방식을 사용한다. 그러나 센서가 적의 기지근처, 인체 조직내 삽입, 건물의 내벽 등과 같이 배터리를 교체할 수 없는 곳에 위치해 있는 경우, 반영구적인 사용에 제한이 있기 때문에 무전원 무선 센서의 개발이 절실히 필요하다. 특히, 이러한 센서를 새롭게 개발하고 검증하려며 센서의 주파수 특성을 분석해야 하는데 기존에는 단순한 파형만을 분석할 수 있는 일반적인 계측기를 사용할 수밖에 없었다. 따라서 본 논문에서는 기존의 계측기보다 유연성 있고 효율적으로 무전원 무선 센서의 개발과 검증이 가능하도록 신호의 모니터링과 신호발생기를 에뮬레이션하는 NI LabVIEW기반의 SAW System Analyzer와 SAW Reader Emulator 시스템을 설계하고 개발하였다.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2014.10a
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• pp.170-172
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• 2014

In this paper, one of reliable schemes of In-ship sensor networks using a Grid-based WPAN is proposed. The proposed scheme is based on a novel grid network which allows a multi-path communication, and is robust, energy efficient. The results demonstrate that the proposed Grid-based WPAN outperforms the IEEE 802.15.4 based network in terms of power efficiency.

• Journal of IKEEE
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• v.25 no.1
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• pp.101-108
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• 2021

This paper proposes a parallel control method of a modular DC/DC converter for electric vehicle (EV) chargers. The EV chargers have been increasing the power capacity using modular converters. There are output current imbalances between the modules, which are caused by the difference of the impedance, delay of the gate driver, and error of the sensors. The conventional strategies for the equal distribution of the output current cause the voltage drop or the high volume and cost of the converters. Therefore, the proposed parallel control strategy effectively balances the output current of modules using a current compensation method. The proposed strategy is verified by simulations. Additional experimental results will be added under various conditions.

• Journal of the Korean GEO-environmental Society
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• v.23 no.10
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• pp.21-31
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• 2022

Prospecting ice on Moon requires drilling systems to obtain subsurface samples and measure composition of ice deposits. Landers and rovers need to be equipped with drilling equipment in order to analyze the ice and subsurface resources located at the poles of Moon. These devices must be small, lightweight, low-power, highly efficient and high-performance units in order to function properly under the extreme conditions of the lunar environment. Researchers have developed a prototype drilling apparatus that is able to operate in atmospheric and cold environments. Newly developed drilling system in Korea, which is capable of performing not only sampling but also subsurface investigation, is introduced.

• Prospectives of Industrial Chemistry
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• v.24 no.4
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• pp.1-21
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• 2021

화석연료의 과도한 사용으로 유발된 기후변화 문제를 해결하기 위해 대체에너지의 개발에 대한 관심이 높아지고 있는 가운데 재생가능하며 친환경적인 수소에너지가 실현가능한 궁극적 대안으로 주목받고 있다. 다양한 수소 생산 기술 중 물의 전기분해를 이용한 수전해 기술은 온실가스와 같은 오염물질을 배출하지 않으며 재생에너지와 연계하여 미이용 전력을 대용량 장주기로 저장할 수 있다는 장점이 있다. 수전해 장치는 수소와 산소를 발생하는 전극과 기체의 섞임을 방지하고 이온을 전달하는 분리막으로 구성되며 그 중 분리막은 수전해 장치의 효율과 안정성을 결정짓는 핵심 부품이다. 본 총설에서는 수전해 기술 중 저온 수전해에 해당하는 알칼라인 수전해(alkaline water electrolysis), 고분자전해질막 수전해(polymer electrolyte membrane water electrolysis)와 음이온교환막 수전해(anion exchange membrane water electrolysis)에 사용되는 분리막에 대한 특성을 분석하고 최근 연구 동향에 대해서 다루고자 한다.

• The Journal of the Korea Contents Association
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• v.9 no.12
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• pp.64-76
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• 2009

Recently, the ubiquitous environment and the practical technology associated with it become more popular topic along with the rapid development of wireless technologies. The necessity of the automated system based on the ubiquitous environment has been increasing when the concept of the ubiquitous is integrated into the fields of existing IT. Also, the necessity of formulating a power-saving plan on large buildings and public institutions is gathering strength because of a raise in exchange rates and high oil prices. In this paper, to efficiently manage the power consumption of the electronic machine such as electric lights, electric heaters, and air conditioners in a building, power-saving manage- ment system using RFID/USN technologies is proposed. Proposed system controls the electric machine and monitor it's condition by RFID and collects the real time information about the surrounding and the power consumption of the electric machine by USN. Especially, proposed system analyzes the real time information and supports the intelligent scheduler with the best power-saving. Finally, this paper shows the difference between proposed system and existing system and establishes thereality of our system through experiments in variety environments.

• Korean Chemical Engineering Research
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• v.55 no.6
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• pp.822-829
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• 2017

As a method to reduce the total phosphorus in sewage treatment plant, we applied the integral type slow mixing/sedimentation fiber filtration system to compare the control methods for the sewage effluent and the reject water. It was analyzed that about 92.4 kg T-P/day should be removed in order to satisfy the final concentration of phosphorus of 0.2 mg T-P/L, which is reinforced effluent standard. Therefore the total phosphorus removal efficiency should be 96% for sewage effluent and 69.2% for reject water (dehydrated filtrate) respectively. The system operation cost to achieve the target of total phosphorus removal efficiency was assessed. It has been found that the treatment cost of the reject water containing high concentration of phosphorus with a low flow rate is reduced to about 1/2.4 of the coagulant cost and about 1/120 of the electricity cost, compared to that of the sewage effluent treatment. Also the economics of the integral type slow mixing/sedimentation fiber filtration system and the general coagulation and sedimentation system were compared. It was evaluated that the development system was more economical because the installation area of the integral type slow mixing/sedimentation fiber filtration system was about 1/7 smaller than that of the general coagulation and sedimentation system, and the annual operation cost including the required amount of coagulant and electricity cost of the development system was lowered about 1/1.7 than that of the general system.

• Clean Technology
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• v.27 no.4
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• pp.277-290
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• 2021

A supercapacitor, also called an ultracapacitor or an electrochemical capacitor, stores electrochemical energy by the adsorption/desorption of electrolytic ions or a fast and reversible redox reaction at the electrode surface, which is distinct from the chemical reaction of a battery. A supercapacitor features high specific power, high capacitance, almost infinite cyclability (~ 100,000 cycle), short charging time, good stability, low maintenance cost, and fast frequency response. Supercapacitors have been used in electronic devices to meet the requirements of rapid charging/discharging, such as for memory back-up, and uninterruptible power supply (UPS). Also, their use is being extended to transportation and large industry applications that require high power/energy density, such as for electric vehicles and power quality systems of smart grids. In power generation using intermittent power sources such as solar and wind, a supercapacitor is configured in the energy storage system together with a battery to compensate for the relatively slow charging/discharging time of the battery, to contribute to extending the lifecycle of the battery, and to improve the system power quality. This article provides a concise overview of the principles, mechanisms, and classification of energy storage of supercapacitors in accordance with the electrode materials. Also, it provides a review of the status of recent research and patent, product, and market trends in supercapacitor technology. There are many challenges to be solved to meet industrial demands such as for high voltage module technologies, high efficiency charging, safety, performance improvement, and competitive prices.

• Journal of Bio-Environment Control
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• v.8 no.2
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• pp.136-146
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• 1999

A series of experiments were carried out in winter to investigate the indoor thermal environment in greenhouses with different kinds of heating systems, and characterize the energy consumption, heat transport and thermal energy efficiency of each system. By the Quantitative calculation of heat losses which transmit through the covers of greenhouse, the fundamental data of energy-saving of the particular heating system were obtained. And from the analysis of air temperature differences between indoor and outside, it was possible to select more effective energy-saving and comfortable heating system in greenhouses. The electric heater was more stable in thermal environment and cheaper in cost, since it could be used during the surplus time of electric power from 10：00 p.M. to 8：00 A.M. But the low air temperature in greenhouses besides these times resulted in a chilling problem of the crops. The heating system by hot air had the advantage to show nearly uniform temperature difference by the height above the ground. But the system had the disadvantage to require more energy consumption than the electric heating system.

• Journal of the Korea Society of Computer and Information
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• v.17 no.1
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• pp.183-192
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• 2012

Although underground water resource has relatively less pollution rate compared with surface water, its recovery faces many difficulties due to poor management. Our country monitors underground water to manage it effectively through auxiliary observation network for underground water. In this paper, we suggest water-well auto measure system based on Geosensor for business efficiency increase of water-well management and realtime monitering. In this system is consist of user GUI(Graphic User Interface) composed with water-well information and movement sub-observation network prototype system composed with GPS(Global Positioning System) and wireless sensor node such as water temperature, water level, electrical conductivity. In this system is using the light of the sun for self-power, variety water-well information collected wireless sensor node was a wireless transmitting/receiving a using CDMA(Code Division Multiple Access) module. Also, for promote with user ease, user GUI express that water-well collected in GIS(Geographic Information System) map. For performance evaluation of the proposed system, we perform experiment using sensing information through designed sub-observation network. And we was proved superiority of the proposed system through qualitative evaluation with other paper.