• 한국신재생에너지학회:학술대회논문집
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• 2011.05a
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• pp.90.2-90.2
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• 2011

세계 각 국에서는 선진국을 중심으로 기후변화와 치솟는 유가에 대응하기 위하여 다양한 에너지원의 확보를 위해 부단히 노력하고 있다. 특히, 신재생에너지원 중 에너지 지속성이 가장 우수한 연료전지의 경우 1kW급 건물용 연료전지시스템이 도시가스 인프라가 가장 우수한 한국 및 일본을 중심으로 상용화에 가장 근접해 있는 실정이다. 일본의 경우 가정용 연료전지시스템 '에너팜'의 일부 제품이 올해부터 200만엔대로 가격을 내려 보급되어질 예정이고, 아직은 경제성이 떨어지지만 연료전지 조기 상용화를 위해 시스템 가격저감을 통한 기술개발이 한창이다. 또한 700W급 고체산화물형 연료전지시스템을 세계에서 처음 시판 계획을 가지고 있다. 국내의 경우 2009년도부터 시작된 '그린홈 보급확대를 위한 건물용 연료전지 보조기기 가격저감 기술개발'연구를 통해 블로워, 밸브, 유량계 및 펌프 등의 보조기기의 단가를 낮추고자 기술개발에 박차를 가하고 있다. 이에 따른 연료전지 부품 가격저감 기술이 국내 건물용 연료전지 시장보급의 활력소가 되기를 기대한다. 본 연구에서는 건물용 연료전지의 보조기기인 블로워의 가격저감을 위한 연구의 일환으로 블로워의 안전성능 평가를 통한 보조기기의 가격저감 및 안전성을 확보하고자 한다. 1kW급 건물용 연료전지시스템의 여러 블로워 중 도시가스용 연료승압 블로워, 선택산화 공기 블로워, 버너 공기 블로워 및 캐소드 공기 블로워의 안전성능 평가를 수행하였고, 평가결과의 공유를 통하여 국내 블로워 제조사의 설계방향을 제시하고 연료전지시스템의 안전성을 확인하고자 한다. 특히, 내구성, 기밀, 가혹조건시험 및 소음, 진동, 습도, 온도와 같은 내주위환경시험 등의 평가결과 비교를 통하여, 연료전지 부품 인증기준을 재정립하여 연료전지 부품산업의 조기 활성화를 도모하고자 한다.

• Journal of Advanced Navigation Technology
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• v.15 no.6
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• pp.1059-1067
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• 2011

Next-Generation ITS environment requires high-speed data packet transmission, security, authentication, and hand-over supportable for driving vehicle on road by installing RSEs and OBUs. Therefore, wireless communication technology for next-generation ITS services are advancing to 200km/h maximum speed supportable, 1km communication radius, minimum 10Mbps hish-speed datarate for multimedia data(such as text, images, movie clips and so on) supportable, high reliability. In this paper, we implemented WAVE communication system which based on IEEE 802.11p PHY/MAC and evaluated that the system meets next-generation ITS environments.

• IEMEK Journal of Embedded Systems and Applications
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• v.5 no.3
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• pp.118-127
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• 2010

Inter-vehicle communication is one of the most important parts in Intelligent Vehicle System. Through this communication, drivers can recognize what is happening out of their sights, such as the freezing condition of the street, traffic accidents, and so on. Each car in IVS gives various services to the drivers after analyzing those received information from cars or a base station. If the message is, however, exchanged from car to car directly, the computation cost which is needed for all the car to authenticate the transmitted message between nearby cars is tremendously high. Therefore, one can naturally think that the message communication between cars is performed with the help of the base station to reduce the computation cost. In this case where the base station collects all the information transmitted from cars and broadcasts them nearby, there should be an efficient way both for the base station to authenticate the car message within its communication range and for the car to authenticate the information received from the base station. In this paper, we present a two-way authentication protocol using a hash chain to efficiently exchange GPS information between a car and a base station. This information can be used to provide a driver with the navigation which displays all the moving cars around him in real time. When a car goes into an area of a base station, the car authenticates itself to the base station using its private key of PKI, sends a commitment of a hash chain, then starts to send a message with the hash value for authentication. The message includes GPS information, driver's status and so on. The base station also authenticates itself to the nearby cars using its private key, transmits the commitment of the hash chain, and sends all the messages gathered from cars with authentication information.

• Journal of Aerospace System Engineering
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• v.12 no.5
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• pp.76-88
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• 2018

Space agencies such as NASA, ESA, and the US military provide guidelines and standards for PA(product assurance) requirements and plans. In recent years, major satellite manufacturers around the world have been mitigating PA requirements and processes by tailoring. PA tailoring has been implemented to improve the cost and schedule efficiency. PA tailoring can be accomplished based on various factors such as mission, classification of mission risk, complexity, development cost, life cycle, etc. In this study, PA tasks according to the mission risk classification proposed by NASA are investigated, and the tailoring method is suggested for the optimization of the development cost and schedule. In particular, the classification of mission risk for the satellites under development or operation in Korea is performed, and PA characteristics in accordance with mission risk are analyzed.

• The Journal of the Korea Contents Association
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• v.21 no.12
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• pp.190-201
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• 2021

The variable message sign (VMS) is equipment to improve the efficiency of traffic flow and safety of travel by providing real-time information to road users on traffic, road, weather situation, and traffic control due to construction. The information messages of the letter-based VMS taking up most of the VMS on the general national highways consist of section, travel time in sections, and road control situation. This study devised an improvement plan centered on road users, not road managers-centered existing message-based VMS through an analysis of road users' preference targeting the letter-based VMS operated in the general national highways in the Seoul Metropolitan Area. By presenting the measure for system improvement through which information on unexpected situations that road users prefer the most can be quickly and efficiently provided, this study aims to improve the efficiency of road user-centered VMS traffic information.

• Journal of the Korean Society for Geothermal and Hydrothermal Energy
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• v.14 no.4
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• pp.20-26
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• 2018

In this study, the performance characteristics of a welded plate heat exchanger was investigated experimentally. Performance tests were carried out according to the flow rate and inlet temperature of working fluid. As a result, the heat transfer capacity increased by 335.5 kW with an increasing the flow rate and temperature difference between hot and cold side. However, the overall heat transfer coefficient was increased with the increase of flow rate, and it was not effected significantly from inlet temperature difference between hot and cold working fluid. The pressure drop was increased by 55.78 kPa with an increasing the frow rate when the flow rate ratio between hot and cold side 1:1. However, the tendency of pressure drop was difference when flow rate ratio wasn't 1:1. In case that the flow rate ratio between hot and cold side was not 1:1, the pressure drop at the low flow rate side was higher than that when the flow rate ratio was 1:1, while pressure drop of the other side was decreased compared to that when the flow rate ratio was 1:1.

• Journal of the Korean Society for Library and Information Science
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• v.55 no.1
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• pp.567-591
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• 2021

This study examined the curriculum of 23 graduate schools of archival sciences in the United States, Canada, the United Kingdom, and Australia and 25 graduate schools of archival sciences in Korea, and compared core knowledge categories. The average number of courses in Korea and other countries was similar, but each university in other countries set required courses, and few in Korea. As a result of comparison by knowledge category, all knowledge categories in North America were opened as individual courses, while the UK and Australia did not open knowledge categories of outreach, instruction, advocacy, and knowledge categories of professionalism separately. In Korea, the category of outreach, instruction, advocacy, the knowledge category of professionalism, and the knowledge category of information technology have not been established separately, while courses related to history and administration are subdivided. In order to reform the archival science education in Korea, the knowledge categories for archival professionals should be prepared and the guidelines and certification standards for the education should be established.

• Journal of the Korean Society of Food Science and Nutrition
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• v.44 no.5
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• pp.716-724
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• 2015

Trienzyme extraction coupled with microplate assay (Lactobacillus casei subsp. rhamnosus) was validated and applied for the determination of folate (vitamin B9) in Korean ancestral rite foods. Foods included five Guk (Tang), eleven Sookchaes, eight Jeoks, nine Jeons, six Jjims, and twenty desserts. Folate was detected in all samples: Guk (Tang) 4.62~18.84, Sookchae 6.13~48.40, Jeok 5.49~49.50, Jeon 6.96~30.77, Jjim 10.34~38.88, and desserts $3.33{\sim}49.55{\mu}g/100g$. The lowest folate content was observed in Sikhye ($3.33{\mu}g/100g$), whereas the highest was observed in Songhwa-dasik ($49.55{\mu}g/100g$). Folate analyses of certified reference materials, BCR-121 (whole meal flour) and BCR-487 (pig liver), showed good recoveries of 90.0% (0.45 mg/kg) and 92.4% (12.3 mg/kg), respectively. The recoveries (96.0 to 106.2%) obtained by analyzing eight spiked samples with different matrices also showed good accuracy. Both repeatability and reproducibility were less than 5%, indicating good precision. The quality control chart (n>30) obtained by running commercial folate fortified-wheat flour once a week for about 10 months showed that all assays were under control. All validation method and analytical quality control results showed that folate contents in Korean ancestral rite foods produced by microplate assay were reliable enough to be used for the construction of a national folate database.

• Journal of Satellite, Information and Communications
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• v.2 no.2
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• pp.41-47
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• 2007

The first geostationary satellite made by Korea, COMS, has the three different payload ; Meteorological sensor, Oceanographic sensor and Ka-band communication payload. There are Meteorological & Ocean Data Communication Subsystem(MODCS) and Telemetry, Command and Ranging Subsystem(TC&R) as other RF radiation sources. MODCS transmits and receives Meteo and Ocean measurement data from/to earth using L-band and TC&R using S-band. The Ka-band communication payload will provide high-speed multimedia services and communication services for natural disaster such as prediction, prevention, and recovery services in the government communications network.Ka-band beacon is for the earth antenna pointing and the experiment of rain fading. This paper gives the analysis results about the mutual radiation effect on Ka-band communication payload, Ka-band beacon, MODCS and TC&R. Up/Down link power and coupling factor including the geometrical position and distance of antenna, filter rejection and degradation factor due to the different polarization are considered. The results show MODCS and TC&R are compatible for Ka-band communication payload and Ka-band beacon does not interfere with MODCS and TC&R normal operation.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.15 no.5
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• pp.473-479
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• 2004

In this paper, power density in near field is calculated about analytic object which has comparatively large volume in considering used wavelength such as cellular base station antenna. Panel sector antenna which is used widespreadly in domestic cellular wireless communication system is modeled and electromagnetic field distribution in reactive near field region is calculated by FDTD (Finite Difference Time Domain) method. After that, antenna gain in far field region is obtain by near to far transformation. Power spectral density in radiated near field is calculated in applying to gain-based model with antenna gain in far field. Finally, compliance distance is obtained in considering the result from radiated near field calculation and basic restrictions on occupational and general public exposure limits in ICNIRP guideline. In the center of main radiating position, the result from gain-based model is -14.55 ㏈m and the result from surface scanning method is -15.75 ㏈m. When the losses from cables and connectors used in measurement are considered, the results from gain-based model and surface scanning method are nearly coincident.