• 한국수소및신에너지학회논문집
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• 제29권5호
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• pp.503-511
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• 2018

There have been many studies of combustion in the circulating fluidized bed. However, little study is available for combustion of wood pellet together fed with wood chip. The mixed ratio of two fuels is an useful information when thermal power company would receive the Renewable Energy Portfolio Standard (RPS) from government. In this study, the combustion behavior and kinetics of such biomass fuels are evaluated using fluidized bed reactor and thermogravimetric analyzers. The mixing ratio of wood chip relative to wood pellet was varied at different temperatures. The results show that a combustion reactivity changed significantly at the wood chip mixing ratio of 40%, particularly at low temperature condition.

• 대한방사선기술학회지:방사선기술과학
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• 제22권1호
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• pp.43-47
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• 1999

In order to obtain effective utilization of intensifying screens[$CaWO_4(W),\;Gd_2O_2S:Tb(Gd)$, BaFCl : Eu(Ba)] over the diagnostic radiology range, we calculated absorption coefficient (${\mu}$), absorption efficiency (${\eta}_{\alpha}$) and absorbed energy ratio(R) and analyzed effects of these properties on X-ray image, finally concluded as below. Regardless of presence of contrast media, absorption coefficient of Gd the highest and decreased with increase of thickness and kVp. Absorption efficiency related with absorbance of fluorescent materials showed the highest value for the Gd, and discontinuous points exhibited at around $80{\sim}90\;kVp$ and $90{\sim}100kVp$ for the Ba and the Gd, respectively. Furthermore, the absorbed energy ratio(R) correspond to contrast of reflection showed the largest value for the W in the absence of contrast media, and for the Gd in the case of the existence of it, and the ratio was decreased with increasing of incident energy. Owing to these properties, we assumed that it was more preferable to use rare earth type intensifying screen for the radiography using in the C.M.(I, Ba), while in the general radiography, $CaWO_4$ intensifying screen was applicable.

• 한국광학회지
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• 제4권1호
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• pp.57-65
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• 1993

용량 이행형 방전여기에 의한 소형 XeCl레이저를 제작하고, 가스 혼합비에 따른 출력특성을 조사하였다. 내자형 capacitor에 의한 자동 예비전리 방식과 2.7 cm 간격의 Chang형상으로 가공된 전극구조의 레이저를 구성하여 2.7cm${\times}$1.5cm 크기의 출력 빔을 얻었고, Xe과 HC1의 농도 변화 및 완충 기체의 종류에 따른 최대 출력 에너지 및 최대 효율 조건을 조사하였다. 최대 레이저 펄스 에너지는 Ne 완충기체를 사용시 230mJ이며, 단위 방전 체적당 1.1 J/l의 에너지를 얻었으며, 최대 에너지 효율은 1.6%이었다. 1:3의 낮은 비율의 피-킹 캐패시턴스의 구성에 의해 레이저 펄스폭은 장펄스 효과를 나타내 foot-to-foot 200 ns로 측정되었다.

• 신재생에너지
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• 제1권1호
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• pp.37-43
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• 2005

High-efficiency silicon solar cells have potential applications on mobile electronics and electrical vehicles. The fabrication processes of the high efficiency cells necessitate com placated fabrication precesses and expensive materials. Ti/Pd/Ag metal contact has been used only for limited area In spite of good stability and low contact resistance because of Its expensive material cost and precesses. Screen printed contact formed by Ag paste causes a low fill factor and a high shading loss of commercial solar cells because of high contact resistance and a low aspect ratio. Low cost Ni/Cu metal contact has been formed by using a low cost electroless and electroplating. Nickel silicide formation at the interface enhances stability and reduces the contact resistance resulting In an energy conversion efficiency of $20.2\%\;on\;0.50{\Omega}cm$ FZ wafer. Tapered contact structure has been applied to large area solar cells with $6.7\times6.7cm^2$ in order to reduce power losses by the front contact The tapered front metal contact Is easily formed by the electroplating technique producing $45cm^2$ solar cells with an efficiency of $21.4\%$ on $21.4\%\;on\;2{\Omega}cm$ FZ wafer.

• Asian-Australasian Journal of Animal Sciences
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• 제11권4호
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• pp.391-397
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• 1998

The present study was conducted to examine the effects of dietary protein (20, 22, 24%) with a constant protein-to-energy ratio on clenbuterol-induced performance in broilers. The protein-to-energy ratio was based on adequate level (22% protein, 3,100 kcal of energy). Female broiler chickens were used for a $3{\times}2$ factorial arrangement and fed diets with or without 1 ppm clenbuterol from 14- to 32-days of age. Feed efficiency improved with increasing dietary protein level, regardless of clenbuterol treatment. The dietary clenbuterol increased weights of breast and leg muscles (gastrocnemius and peroneus longus), and clenbuterol markedly reduced protein content of leg muscles in chickens fed the 20% protein diet, but did not in chickens fed the 22 and 24% protein diets. Feeding the 24% protein diet with clenbuterol improved the protien accretion (peroneus longus) by 8.4%. Clenbuterol decreased DNA content and increased the protein/DNA ratio in breast muscle regardless of dietary protein intake. Clenbuterol had no effect on RNA content in both breast and leg muscles. The present results demonstrated that various protein levels which retain the same protein-to-energy ratio in the diet markedly alter the protein accretion induced by ${\beta}$-agonist in broilers.

• 한국대기환경학회지
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• 제15권4호
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• pp.475-483
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• 1999

A lab-scale test was carried out to study the reduction of electrical energy consumption in the pulsed corona discharge process for nitrogen oxides removal. The experiment was mainly focused on 1) the activation of pollution removal reactions by chemical additives and 2) the optimization of electrical circuit for the efficient energy transfer from the power supply to the corona reactor. Hydrocarbon chemical additives used in the experiment are thought to be responsible for the enhancement of the NO conversion through the chain reactions of free radicals such as, R, RCO, and RO. Electrical energy consumption per converted NO molecule has a minimum value of 17 eV when pentanol is injected. When ethylene and propylene are injected, 30 eV and 22 eV of electrical energy consumption is required for the conversion of NO molecule respectively. The ratio of the pulse forming capacitance$(C_e)$ to the reactor capacitance$(C_R)$ plays an important role in the energy transfer efficiency to the reactor. Maximum energy transfer efficiency of approximately 72% could be obtained by using the pulse forming capacitance which is 3.4 times larger than the reactor capacitance, and also the maximum NO conversion efficiency was observed with the same condition.

• Environmental Engineering Research
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• 제24권2호
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• pp.238-245
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• 2019

This study investigated the characteristic of aerobic granular sludge (AGS) process to treat the sewage having low carbon/nitrogen ratio (Biochemical oxygen demand ($BOD_5$):Total nitrogen (T-N), 4.5:1) in sequencing batch reactor (SBR). The removal efficiency of $BOD_5$, suspended solid (SS), T-N and phosphorus ($PO_4{^{3-}}$-P) were 92.6%, 64.3% and 90.1%. Concentration and size of AGS were changed in proportion to the organic matters and nitrogen concentration of the influent (Concentration and size of AGS: 1,700-3,000 mg/L, 0.5-1.0 mm). Mixed liquor suspended solid (MLSS) also changed with the concentration of AGS (MLSS: 2,000-3,500 mg/L). When the settling time was shortened from 15 min to 10 min, size and shape of AGS were maintained (Size of AGS: 1.0-1.5 mm). In addition, the concentration of AGS and MLSS increased (Concentration of AGS: 3,500 mg/L, MLSS: 4,000 mg/L). Concentration, size and shape of AGS were affected the settling time of the reactor more than the concentration of organic matter and nitrogen in the influent. In the results of removal efficiency and changes in AGS, we confirmed that the SBR process using AGS can be used to treat the sewage having low carbon/nitrogen ratio by applying short settling time.

• 인터넷정보학회논문지
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• 제15권2호
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• pp.9-18
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• 2014

인체에 부착된 센서들의 위치는 인간의 신체적 활동에 따라 자주 이동된다. 이에 따른 노드 위치 이동과 비가시선상의 문제들은 무선 인체 통신망에서 핫 스팟과 에너지 효율, 그리고 신뢰적인 통신 성능에 영향을 미친다. 우리는 빈번히 변화하는 네트워크 토폴로지와 채널 조건을 고려한 포워딩을 결정하는 방법을 제안하였다. 본 논문에서는 각 노드의 라우팅 레벨에서 입, 출력 링크들의 비율에 근거하여 포워딩 비율과 패킷들의 크기를 제어한다. 또한 패킷 크기와 포워딩 비율 제어를 지원하는 격자 기반의 연결을 확장함으로써 네트워크 토폴로지를 견고하게 한다. 본 논문의 시뮬레이션은 이러한 접근들이 네트워크 수명을 48.2% 증가시키는 것뿐 아니라 약 6.08%의 패킷 전달율의 증가가 있음을 증명한다. 또한 핫 스팟 문제도 본 제안을 통해 해결된다.

• 한국수소및신에너지학회논문집
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• 제7권1호
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• pp.3-9
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• 1996

금속과 물의 혼합체에 전기방전을 야기시켜 수소를 제조하는 방법은 필요시에 즉시 수소를 제조할 수 있는 유용한 방법이다. 그러나 이 방법이 실제로 이용될 수 있기 위해서는 입력되는 전기에너지당 물과의 반응을 일으키는 금속의 양이 가능한한 큰 값을 가져야 한다. 이러한 에너지 효율을 높이기 위해서는 약한 전기방전이 화학반응을 지속시킬 수 있어야 된다. 이러한 효율에 직결되는 실험변수중에서 방전 전압-전류 곡선을 측정하여 토의하였다.

• 한국태양에너지학회 논문집
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• 제24권4호
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• pp.77-87
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• 2004

BIPV or double skin applied to the surface of the building, power and thermal load cannot both be increased. In the case of BIPV, because it is applied to the facade, incident solar energy decreases and efficiency drops off. The system in this paper complements these disadvantages and aims to decrease the heating & cooling load by transforming solar energy to electronic and thermal energy. The research in this paper is about the applicability of the clear PV attached double-skin system. And the PV electronic generation and the factors that affect the heating & cooling load such as the daily radiation, sun shading ratio, heating & cooling load, daylight luminance and glare distributions in the building are simulated.