• Proceedings of the KSR Conference
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• 2008.06a
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• pp.948-951
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• 2008

Ubiquitous sensor network (USN) based on ZigBee communication protocol has been used in various application fields, such as home-network, intelligent building and machine, logistics, environmental monitoring, military field, security field and etc. The ZigBee is targeted at radio-frequency application that require a low data rate, long battery life and secure network. Especially, the USN system can be applied efficiently to building-indoor where the complex geometry is adopted. In this study, all 90 points of railway cabin indoor were monitored for temperature and humidity using USN technology. All sensors were pre/post-calibrated and the temperature/humidity change were analyzed in a railway cabin in real-time. The results would be useful to develop the cabin heating, ventilating and air conditing (HVAC) system to meet all passengers' thermal comfort regardless of their seat position.

• Proceedings of the Membrane Society of Korea Conference
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• 1994.10a
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• pp.34-35
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• 1994

기체혼합물의 분리및 정제기술은 에너지 절약의 관점과 새로운 기능성 고분자의 개발로 고분자막에 의한 분리법이 관심을 끌게되었다. 공기로부터 산소부화, 방사성 크세논 및 크립론의 제거, 제련소 폐가스증의 수소분리, 천연가스로부터 헬륨의 회수분야등은 실제로 산업적으로 실용화되고 있다. 그러나 고분자막은 일반적으로 투과성과 선택성이 서로 상반되는 경향을 나타내므로, 투과성과 분리성이 좋은 기능성 고분자막의 개발에 다양한 연구가 필요로 하고있다. 본 연구에서 사용한 PTFE(polytetrafluoroethylene)는 결정성 고분자로서 넓은 온도범위에서 낮은 마찰계수, 우수한 전기적 절연특성, 강한 Carbon-fluorine 겹합에 기인한 높은 열적 안정성, 화확적 불활성때문에 공업용 고분자 재료로서 독특한 위치를 차지하고 있다. 최근에 미국과 일본을 주축으로 상용화딘 공기전지(Zinc-air battery)는 PTFE막의 뛰어난 소수성과 화학적 저항성으로 수은 전지의 대체품으로 주목받고 있는데, 장기 방전시 성능 저하가 따르므로 막을 통한 산소투과성을 방전에 필요한 최소값으로 감소시키는 것이 중요한 과제가 되고있다.

• Proceedings of the KIEE Conference
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• 1994.07b
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• pp.1543-1546
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• 1994

Ignitabilility of explosive gas mixture by spark of dry cell in case of short circuit by accident was studied for the purpose of evaluation of intrinsically safe characteristics of dry cell that manufactured in Korea. IEC type spark test apparatus, $21{\pm}2$ Vol% of hydrogen - air mixture, and dry cell that produced in Korea was used for the experiment. The result of this research could be used for design, manufacturing, and using the intrinsically safe electrical apparatus.

• The Transactions of the Korean Institute of Power Electronics
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• v.22 no.5
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• pp.373-381
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• 2017

The electric vehicle market has increased rapidly in recent years. Established global automakers have announced that electric cars will be developed and distributed. Furthermore, current electric cars are not merely breezes, instead, they are the mainstream of automobiles. However, high prices, short mileage, and long charge times are the main obstacles to the spread of electric vehicles. To solve these problems, the competition for technology development for the expansion of electric vehicles worldwide intensifies because of the improvements in mileage, price reduction, and expansion of charging infrastructure. In this paper, the trends in the development of key technologies for electric vehicles in overseas markets and the present strategic goals for the development of key technologies for electric vehicles in Korea will be identified.

• Proceedings of the KSR Conference
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• 2003.05a
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• pp.139-144
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• 2003

This study was aimed to establish failure management plan of the rubber-tired AGT light rail vehicle for its safety case, which was developed according to the Korean standardized specifications for the light rail vehicle. Vehicular 9 failure modes anticipated during the system operation were considered, which are single malfunction of redundant equipment, malfunction of train radio, public address and air compressor, battery, main circuit NFB trip, on-board ATO control device malfunction, on-board ATP control device malfunction, fail of brake release, flat tire, train emergency door open.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2006.05a
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• pp.334-337
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• 2006

외과수술용 핸드피스는 현재 국내 외 병원에서 사용되고 있는 수술 장비 중 필수 보유 장비이다. 선진수술 기법인 인공관절대체수술 시 뼈(Bone) 절단, 다듬질, 구멍등 초섬세 가공을 목적으로 하는 기기이다. 기존의 공압식(Air Type)은 수술 시 많은 양의 질소(N2 Gas)가 소모됨으로써 질소탱크 보관에 많은 공간이 필요하고 잦은 교체를 필요로 한다. 또한 기계소음과 공압식 호스의 이동으로 시술자와 환자사이에 불편함이 발생하고 감염의 위험성이 있으므로 최근에는 충전식을 선호하고 있다. 이러한 이유로 기존의 공압식을 대체할 배터리형 외과수술용 핸드피스를 연구하게 되었다.

• Electronics and Telecommunications Trends
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• v.38 no.6
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• pp.128-136
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• 2023

Lithium accounts for only 0.0017% of the earth crust, and it is produced in geographically limited regions such as South America, the United States, and China. Since the first half of 2017, the price of lithium has been continuously increasing, and with the rapid adoption of electric vehicles, lithium resources are expected to be depleted in the near future. In addition, economic blocs worldwide face intensifying scenarios such as competition for technological supremacy and protectionism of domestic industries. Consequently, Korea is deepening its dependence on China for core materials and is vulnerable to the influence of the United States Inflation Reduction Act. We analyze post-lithium secondary battery technologies that rely on more earth-abundant elements to replace lithium, whose production is limited to specific regions. Specifically, we focus on the technological status and issues of sodium-ion, zinc-air, and redox-flow batteries. In addition, research trends in post-lithium secondary batteries are examined. Post-lithium secondary batteries seem promising for large-capacity energy storage systems while reducing the costs of raw materials compared with existing lithium-based technologies.

• Journal of the Korean Electrochemical Society
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• v.13 no.1
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• pp.19-33
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• 2010

The surface film, which is formed on graphite negative electrodes during the initial charging, is a key component in lithium secondary batteries. The battery reactions are strongly affected by the nature of the surface film. It is thus very important to understand the physicochemical properties of the surface film. On the other hand, the surface film formation is a very complicated interfacial phenomenon occurring at the graphite/electrolyte interface. In studies on electrode surfaces in lithium secondary batteries, in-situ experimental techniques are very important because the surface film is highly reactive and unstable in the air. In this respect electrochemical atomic force microscopy (ECAFM) is a useful tool for direct visualizing electrode/solution interfaces at which various electrochemical reactions occur under potential control. In the present review, mechanism of surface film formation and its correlation with electrolyte are summarized on the basis of in-situ ECAFM studies for understanding of the nature of the surface film on graphite negative electrodes.

• Journal of Hydrogen and New Energy
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• v.28 no.1
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• pp.56-62
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• 2017

Although most electricity production contributes to air pollution, the vehicle organizations and environmental agency categorizes all EVs as zero-emission vehicles because they produce no direct exhaust or emissions. Currently available EVs have a shorter range per charge than most conventional vehicles have per tank of gas. EVs manufacturers typically target a range of 160 km over on a fully charged battery. The energy efficiency and driving range of EVs varies substantially based on driving conditions and driving habits. Extreme outside temperatures tend to reduce range, because more energy must be used to heat or cool the cabin. High driving speeds reduce range because of the energy required to overcome increased drag. Compared with gradual acceleration, rapid acceleration reduces range. Additional devices significant inclines also reduces range. Based on these driving modes and climate conditions, this paper discusses the performance characteristics of EVs on energy efficiency and driving range. Test vehicles were divided by low / high-speed EVs. The difference of test vehicles are on the vehicle speed and size. Low-speed EVs is a denomination for battery EVs that are legally limited to roads with posted speed limits as high as 72 km/h depending on the particular laws, usually are built to have a top speed of 60 km/h, and have a maximum loaded weight of 1,400 kg. Each vehicle test was performed according to the driving modes and test temperature ($-25^{\circ}C{\sim}35^{\circ}C$). It has a great influence on fuel efficiency amd driving distance according to test temperature conditions.

• Journal of Advanced Marine Engineering and Technology
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• v.41 no.3
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• pp.245-250
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• 2017

Worldwide environmental regulations have been enhanced for emission reduction of greenhouse gases and air pollutants; accordingly, some measures were prepared. Furthermore, the need for effective and reasonable energy-saving methods is growing in accordance with that for environmental pollution minimization. In the case of marine engineering, techniques for the development of eco-friendly vessels have been actively studied, including reduction of exhaust gas emissions, development of alternative fuel, and development of a new propulsion system. In this study, we presented the basic concepts and analyzed the speed, current, voltage, and output power characteristics of each operating mode, i.e., operating mode of battery, generator, and full power.