• Journal of the Korean Solar Energy Society
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• v.34 no.1
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• pp.39-47
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• 2014

Solar applications analysis and building energy performance depend on the quality of the solar resource data available. Unfortunately, most of the weather stations do not measure solar radiation data in Korea, as a reason many researchers have studied different solar radiation estimation models and suggested to apply them to various locations in Korea. In addition, they also studied the impact of hourly global solar radiation on energy performance of an office building by comparing the simulated building energy consumptions using four different weather files, one using measured, and three estimated solar radiation from different models, which are Cloud-cover Radiation Model (CRM), Zhang and Huang Model (ZHM), and Meteorological Radiation Model (MRM), and concluded that there was some impact on energy performance of the building due to the using different solar radiation models. However, the result cannot be applied to all other buildings since the simulated office building for that study only used limited building characteristics such as using fixed values of solar heat gain coefficient (SHGC) and window-to-wall ratio (WWR), which are significant parameters related to solar radiation that affect to the building energy consumptions. Therefore, there is a need to identify how the building energy consumption will be changed by varying these building parameters. In this study, the impact of one measured and three estimated global solar radiation on energy performance of the office building was conducted taking account of SHGC and WWR. As a result, it was identified that the impact of four different solar radiation data on energy performance of the office building was evident regardless SHGC and WWR changes, and concluded that the most suitable solar models was changed from the CRM/ZHM to the MRM as SHGC and WWR increases.

• Nuclear industry
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• v.37 no.8
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• pp.24-33
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• 2017

영화 '판도라'에 투입된 정도의 돈은 막대한 예산을 갖고 있는 국제 그린피스나 매년 전 세계 TV 광고에만 수천만 달러를 쏟아 붓는 천연가스 이익단체들의 예산에 비하면 조족지혈의 수준이다. 국제 그린피스의 연간 예산이 대략 4억 달러, EDF가 1억4천만 달러, 천연자원보호협회(NRDC)와 시에라클럽이 1억 달러가 넘고, 이들 단체가 예금이나 주식에 투자한 돈만 해도 수억 달러나 된다. 시에라클럽이나 NRDC, EDF는 블로그에 원자력을 화석연료로 대체하는 것에 반대하는 글을 올리면서 다른 한편으로는 뉴욕에 있는 Indian Point, 캘리포니아에 있는 Diablo Canyon, 그리고 오하이오에 있는 여러 원전들을 천연가스로 대체해야 한다고 주장하는 기만책을 쓰고 있다. 자연과의 조화를 위해서라도 신재생에너지를 사용해야 한다는 그들 주장의 베일 뒤에는 더 큰 어두운 그림자가 깔려 있다. 가난한 나라는 계속해서 가난하도록 해야 '과잉 인구'와 '과소비'를 막을 수 있다는 반인륜적인 멜더스(Malthusian) 이론과 그들이 주장하는 반핵의 오랜 역사는 서로 그 맥을 같이하고 있기 때문이다. 탈원전이 추진되면 전기요금도 올라가고 실업률도 증가한다는 사실, 그리고 환경 오염도 더 심해지고 그로 인해 조기 사망자 수도 증가한다는 사실을 보여주는 데 반드시 어려운 경제 모델이나 환경 모델이 필요한 것은 아니다. 원자력을 천연가스로 대체하면 그에 따른 비용 상승이 연간 최소 110억 달러나 된다. 물론 신재생에너지로 대체하게 되면 그 상승폭은 더욱 커지게 된다. 그리고 한 경제 분석 전문기관의 연구에 따르면 전기요금이 상승되면 한국의 경제는 저성장에서 벗어나지 못하게 된다. 결국 지금 우리에게 가장 필요한 것은 원자력 휴머니즘, 즉 원자력 에너지가 갖고 있는 훌륭한 도덕적인 목적을 다시 한 번 상기하면서, 우리 인류가 가지고 있는 가장 중요한 환경 기술을 반인륜적인 집단으로부터 구해내기 위한 풀뿌리 시민사회의 가열찬 노력이라고 할 수 있다. 우리와 같은 원자력 휴머니스트들에게는 그린피스나 기타 여러 반인륜적 집단들이 갖고 있는 풍부한 자원이 없다. 그러나 우리에게는 그런 종류의 자원이 필요한 것이 아니다. 우리에게는 그것보다 훨씬 더 중요한 진실이라는 자원이 있다는 사실을 결코 잊어서는 안될 것이다.

• Journal of KIISE:Computing Practices and Letters
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• v.16 no.1
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• pp.80-84
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• 2010

Data multicasting from a source to multiple sinks in wireless sensor networks is used to achieve both reducing communication costs and energy efficiency. Almost all existing schemes for the multicasting might be effectively performed by optimal construction of a multicasting tree between a source and multiple stationary sinks. However, in practical sensor applications, sinks could move around on the wireless sensor networks for own missions, such as scouting of soldiers and saving lives of victims by firefighters. Unfortunately, the sink mobility causes frequent entire reconstruction of the multicasting tree and thus it leads to exhaustion of battery power of sensors. Hence, we propose an energy-efficient multicast protocol to support multiple mobile sinks by the local multicast tree reconstruction, called Local Update-based geographic Multicasting for Mobile sinks (LUMM) for wireless sensor networks. Our simulation results show that our scheme for mobile sinks is more efficient in terms of energy resource management than other exist works.

• Applied Chemistry for Engineering
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• v.22 no.4
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• pp.400-404
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• 2011

The activity and stability of the metal filter material Pt coated on NOx and soot oxidation were examined. The catalytic reaction test for NOx and soot were also performed independently and simultaneously. As a result, it showed the NO to $NO_2$ shift reaction with 20% conversion, NOx decomposition (about 10%) and perfect soot oxidation on the material Pt coated proceeded. Onset temperature of soot oxidation shift to lower temperature (about $30^{\circ}C$) by generated $NO_2$. The material also was less affected by thermal shock than $Pt/Al_2O_3$ or $Pt/TiO_3$ catalysts due to its stability of surface structure.

• Journal of the Korean Solar Energy Society
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• v.27 no.3
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• pp.155-160
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• 2007

This study shows the results on thermal performance test with domestic solar collector for low-temperature applications using KS, then reveals the efficiency difference between KS and EN standard. Using the test results, this study Presents the status of thermal performance with domestic solar collector including flat-plate, single evacuated, and double evacuated (with mirror or U-tube) solar collector.

• New & Renewable Energy
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• v.5 no.3
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• pp.4-12
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• 2009

The effect of change in DFIG (doubly-fed wind power generator) rotating speed and active power on the grid was analyzed to understand the characteristics of wind power using the wind power simulator connected to the grid at Gochang Power Quality Test Center. Electric power quality improvement devices (DVR, STATCOM, SSTS) and electric power quality disturbance application devices for 22.9 kV grid are equipped at Gochang Power Quality Test Center. Induction motor and VVVF inverter were used to emulate the blade of a wind power generator, and a simulator for Cage wound induction generator and DFIG was developed. The trial line were assumed to be 20 km and 40 km in length, and variable wind speed pattern was set using wind speed data from Ducjeokdo to verify the power characteristics of the wind power generator according to rotating speed.

• 한국신재생에너지학회:학술대회논문집
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• 2010.11a
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• pp.64.2-64.2
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• 2010

The objective of this study is to make a comparative study of the operation performance of different type of solar collectors. A flat-plate collector, a single-glazed evacuated collector and a double-glazed evacuated collector are used in this study. These 3 type of collectors are connected in series in the order of a flat-plate collector, a single-glazed evacuated collector and a double-glazed evacuated collector. This experimental facility is a kind of a solar system with a controller, a heat exchanger, a storage tank and a circulation pump. Each collector has a different collection area(flat-plate collector-$6.00m^2$ total area/$5.61m^2$ aperture area, double-glazed evacuated collector-$6.04m^2$ total area/$4.92m^2$ aperture area, single-glazed evacuated collector-$7.65m^2$ total area/$5.61m^2$ aperture area) and its performance characteristic respectively. The experiments have been demonstrated at around $70^{\circ}C$ operating temperature(flat-plate collector inlet temperature). The thermal collecting efficiencies of each collector are obtained under the different insolation and operation condition as a result.

• Journal of the Korean Society for Geothermal and Hydrothermal Energy
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• v.4 no.2
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• pp.1-7
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• 2008

GSHP(Ground Source Heat Pump) has been extensively disseminated due to the recent increasing demand over new and renewable energy. However, the system reliability has been key issues and barriers to insure a better system performance as designed originally in ISO (international standard organization) standard. This paper introduces a systematic method to verify its intended design target so called as ISO performance data based commissioning technology for a water to air GSHP system. The commissioning technology starts from are to the international standard ISO performance data of a GSHP model and to compare its installed operation data and to calibrate and tune to the target optimum operation parameters. Results indicated that cooling capacity could be raised up to 76.6% from 46.6% from this proposed commissioning technology.

• Journal of the Korean Society for Geothermal and Hydrothermal Energy
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• v.5 no.1
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• pp.7-11
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• 2009

The purpose of this study is to investigate the performance of a water heat source cascade heat pump system R717(Ammonia) is used for a low-stage working fluid while R134a is for a high-stage. In order to gain a high temperature supply water in winter season, the system is designed to perform a cascade cycle. In this study, two experiments were carried out. One is a system starting test from the low load temperature of $10^{\circ}C$. The other is a system performance investigation over the R717 compressor capacity changes. Experimental results show that when it starts from the low load temperature, the suction temperature of the low-stage compressor is higher than that of a high-stage. The system performance increases when a water source temperature or a low-stage compressor rotational frequency goes higher.

• Transactions of the Korean hydrogen and new energy society
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• v.17 no.1
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• pp.39-46
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• 2006

Highly ordered Li dispersed nickel oxide nanotubes were prepared with anodic aluminum oxide (AAO) template for hydrogen storage. Electron microscope results showed that uniform length and diameter of nickel oxide nanotubes were obtained. The wall thickness and outer diameter of nickel oxide nanotubes are about 40 - 50 nm and 200 - 400 nm, respectively. It was observed that the diameter of nickel oxide nanotubes is bigger than the pore diameter of AAO template. Li dispersed nickel oxide were consisted of nanoflakes and had structures of nanotubes and nanorods. For increasing the hydrogen adsorption and desorption capacity, the Li dispersed nickel oxide nanotubes were fluorinated. The fluorinated Li dispersed nickel oxide nanotubes showed 1.65 wt% of the hydrogen adsorption capacities at 77 K under 47 atm.