• 한국산학기술학회논문지
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• 제11권12호
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• pp.4984-4990
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• 2010

기존의 DC-DC Converter에서는 전압 변화 및 에너지 축적소자로서 자성부품인 인덕터를 사용하여 자속 발생에 의한 전력 손실로 효율이 낮아지고, 자성부품의 부피가 크고 무거우며 가격이 비싸 반도체 칩으로 집적화하기에 문제점을 가지고 있다. 이러한 문제점을 개선하기 위해 본 논문에서는 인덕터없는 스위치드 커패시터 방식을 이용한 저전력 강압형 CMOS DC-DC Converter를 제안한다. 제안된 DC-DC Converter는 0.5um 공정을 이용하여 설계하였으며, 설계된 DC-DC 컨버터는 200kHz의 주파수로 동작하며 96%이상의 전력효율을 cadence 시뮬레이션을 통하여 얻을 수 있다.

• 한국정보통신학회논문지
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• 제17권9호
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• pp.2063-2072
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• 2013

스마트 그리드란 기존 전력망에 IT기술을 접목하여 공급자와 소비자가 양방향으로 실시간 전력정보를 교환함으로써 에너지 효율을 최적화하는 전력망이다. 기존의 폐쇄이던 전력망이 다양한 이해당사자가 참여하는 상호운용성이 보장되는 개방형 구조를 가지게 됨으로써 이에 대한 보안 기술 개발이 시급한 상태이다. 이러한 스마트그리드의 보안 위협에 대응할 수 있는 안전한 환경을 구축하기 위해서는 보안 메커니즘 개발에 핵심이 되는 키 관리 기법이 필수적으로 요구된다. 본 논문에서는 이중 해쉬 체인을 이용하여 스마트그리드 환경에 효율적으로 적용 가능한 키 관리 프레임워크를 제안하고, 제안하는 키 관리 프레임워크의 안전성 및 효율성을 분석한다.

• 한국멀티미디어학회논문지
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• 제20권12호
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• pp.1960-1969
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• 2017

There have been ongoing researches to identify and analyze the patterns of electric power IoT data inside sensor nodes to supplement the stable supply of power and the efficiency of energy consumption. This study set out to propose an analysis process for electric power IoT data with the K-means algorithm, which is an unsupervised learning technique rather than a supervised one. There are a couple of problems with the old K-means algorithm, and one of them is the selection of cluster number K in a heuristic or random method. That approach is proper for the age of standardized data. The investigator proposed an analysis process of selecting an automated cluster number K through principal component analysis and the space division of normal distribution and incorporated it into electric power IoT data. The performance evaluation results show that it recorded a higher level of performance than the old algorithm in the cluster classification and analysis of pitches and rolls included in the communication bodies of utility poles.

• 펄프종이기술
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• 제36권3호
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• pp.15-34
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• 2004

Diverse benefits such as reduction of fresh water consumption and effluent discharge, efficient use of raw materials and energy savings can be obtained by papermaking system closure. Closure of papermaking processes, however, causes many problems including reduction of the efficiency of additives, decrease of retention and dewatering, felt plugging, poor Paper quality, generation of slime and odor, poor vacuum efficiency, etc, and it has been recognized that accumulation of Inorganic and organic substances in the process white water is the prime cause of these problems. Therefore, technological developments for preventing accumulation of these detrimental substances are urgently required for Implementing papermaking system closure. Understanding of the accumulation phenomena of the inorganic and organic substances in the papermaking process white water is prerequisite for papermaking system closure. In this study a process simulation method was used to analyze the accumulation phenomena of anionic starch In the process white water as the closure level of a fine paper making process is increased. A pilot paper machine was used as a model process. Starch adsorption and desorption models were developed based on the concept of starch adsorption ratio, which was not considered in previous studies. Steady state simulation studies were carried out based on this model using a commercial simulator. In steady state simulation, the variation of dissolved starch concentration in each process unit was monitored as a function of white water usage for wire shower. The result of the steady state simulation showed that dissolved starch concentration and its increase ratio in Process units increased as white water usage ratio for wire shower increased.

• 한국ITS학회 논문지
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• 제9권3호
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• pp.59-66
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• 2010

일반적으로 고속도로 영업소에서는 요금정산을 위해 차량이 감속, 정지, 가속행위를 행해야 하므로, 차량의 멈춤 없이 요금을 징수하는 자동요금징수체계(ETCS)의 일종인 하이패스차로 이용시보다 추가적인 연료소모가 발생하게 된다. 본 연구는 이를 증명하기 위해 현장 실험구간을 선정하고 연료소모량을 측정할 수 있는 실험용 차량을 제작하여 고속도로 영업소 이용방식에 따른 연료소모량을 비교하였다. 실험 결과, 일반차로를 이용하는 차량이 하이패스차로를 이용하는 차량보다 36.7%이상의 추가적인 연료소모가 발생하는 것으로 나타났다. 이에 근거하여 고속도로 상에서 2009년 1월부터 5월까지 실험차량과 동일한 차량들의 하이패스차로 이용에 의한 연료절감 효과를 추정해 본 결과 약 53.4억원의 연료소모비 절감효과가 나타났다. 실제 차량을 이용한 이러한 실험 방법과 분석결과는 하이패스 시스템의 효율성을 증명하는데 유용하게 활용될 것으로 기대된다.

• 한국ITS학회 논문지
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• 제12권1호
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• pp.109-120
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• 2013

본 논문에서는 태양광 발전을 이용한 하이브리드 도로조명 제어 시스템 설계를 제안한다. 제안하는 하이브리드 도로조명 점등제어 시스템은 태양광 발전을 이용하여 하이브리드 컨트롤러를 통해 전원을 공급하고 도로조명을 점등제어가 가능하도록 설계한다. 전력 부족시 상시전력을 공급하도록 제어하고 인체 감지시 자동 조명 제어가 되도록 게이트웨이는 도로조명에 zigbee를 이용하여 제어명령을 전송한다. 미리 설정해 놓은 타임 스케줄에 의해 시스템의 상태를 결정하고 동작시키는 점등제어 알고리즘을 적용한다. 본 논문에서 제안하는 하이브리드 도로조명 점등제어 시스템의 효율성 분석결과, 등주 당 하루에 129.6W의 전력소비를 하였고 1개월간 3.8KW, 연간 47.3KW를 소비하였다. 결과적으로 기존의 점등제어 시스템보다 76.2%의 전력소비량 감소와 76.8%의 전력요금이 감소되어 에너지 효율을 높일 수 있었다.

• 상하수도학회지
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• 제25권6호
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• pp.815-824
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• 2011

In this study, a non-thermal plasma system was employed to simultaneously remove odorous compounds and organic sludge. The system consisted of two reactors; the first one was the non-thermal plasma reactor where ozone was produced by the plasma reaction and the ozone oxidized hydrogen sulfide, the model odorous compound, and then the ozone-laden gas stream was introduced to the second reactor where wasted sludge was disintegrated and solubilized by ozone oxidation. In this study, the gas retention time (GRT) and the hydraulic retention time (HRT) were changed in the two-reactor system, and the effects of GRT and HRT on reduction efficiencies of odor and sludge were determined. As the GRT increased, the ozone concentration increased resulting in an increasing efficiency of hydrogen sulfide removal. However, the overall ozone loading rate to the second sludge reactor was the same at any GRT, which resulted in an insignificant change in sludge reduction rate. When HRTs in the sludge reactor were 1, 2, 4 hours, the sludge reduction rates were approximately 30% during the four-hour operation, while the rate increased to 70% at the HRT of 6 hours. Nevertheless, at HRTs greater than 4 hours, the solubilization efficiency was not proportionally increased with increasing specific input energy, indicating that an appropriate sludge retention time needs to be applied to achieve effective solubilization efficiencies at a minimal power consumption for the non-thermal plasma reaction.

• Asian-Australasian Journal of Animal Sciences
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• 제7권3호
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• pp.383-387
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• 1994

Six heifers each of $F_1$, $F_2$, $F_3$, $F_4$ H. Friesian $\times$ Sahjwal halfbreds and pure Sahiwal with overall average initial age and live weight of $315.6{\pm}134.8 days$ and $143.8{\pm}48.5kg$, respectively were used for this study. The under trial animals were fed according to N.R.C. (1978). The overall average age at maturity, first conception and first calving was $563.8{\pm}116.8$, $675.8{\pm}135.6$ and $956.8{\pm}149.8days$ with live weights as $302.2{\pm}58.6$, $342.6{\pm}41.5$ and $433.9{\pm}38.1kg$, respectively. The overall 305 days and total milk yield for 1st lactation was $2,729.0{\pm}669.3$ and $2,992.7{\pm}377.5litre$ while the FCM (at 4%) was $2,934.2{\pm}410.8litre$. The lactation length was $336.6{\pm}69.6days$. The fat and solids not fat contents were $4.5{\pm}0.2$ and $8.2{\pm}0.3percent$, respectively. The milk production in Sahiwal cows was significantly lower than crossbred cows. The services per conception were $2.5{\pm}1.3$. The overall per head per day consumption of DM, TCP and ME was $10.9{\pm}1.2kg$, $1,399{\pm}199gm$ and $22.6{\pm}2.4 M.Cal.$, respectively. The overall milk producing efficiency for the production of one litre of FCM was $1.12{\pm}0.15kg$ of DM, $142.2{\pm}17.76gm$ of TCP and $2.31{\pm}0.27M.Cal.$ of energy while the feeding cost was Rs. $1.46{\pm}0.22$ per litre of FCM produced. The feeding cost per litre FCM was significantly higher in Sahiwal and $F_2$ than in other genetic groups.

• International Journal of Fluid Machinery and Systems
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• 제10권1호
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• pp.30-39
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• 2017

In the current study, identifying regimes and behaviors of the various viscous fluids in a typical horizontal single-stage centrifugal pump and improving its performance by enhancing volute throat area have been surveyed numerically and experimentally. Indeed the initial pump had insufficient head at BEP (Best Efficient Point) in relevant applications. In order to solve this problem, the method of increasing the volute throat area on the prototype was used in steps and eventually the increased head values have been achieved. Then modified centrifugal pump, that has been constructed based on the modified control volume from numerical results, has been tested thoroughly. The maximum head and efficiency discrepancy between numerical and experimental results in BEP were 1.4 and 2.6% respectively. The effects of viscous fluids, from 1 cSt to 500 cSt, on the performance curves of centrifugal pump have been investigated as well and results showed that viscous fluids has significant effect on them. Indeed the highest head and efficiency in the same conditions at BEP has been obtained in viscosity 1 cst which was by 19.2% and 44% greater than the viscosity 500 cSt. It is also found that the highest viscous fluid had the highest energy consumption as the absorbed power of highest viscous fluid, 500 cSt, increased up to approximately 55% above the lowest viscous fluid, 1 cSt, values.

• 보존과학회지
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• 제26권2호
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• pp.133-142
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• 2010

태안 마도 출토 도자기를 대상으로 도자기 탈염에 일반적으로 사용되는 물 세척법에 추가조건(탈염수 양, 교반 및 온도)을 적용하여 탈염효율을 비교 연구하였다. 탈염수 양에 따른 효율실험결과 질량비 20배가 질량비 10배보다 효율은 높았지만, 그 정도가 2배에 미치지 못하여 경제적 측면에서 질량비 10배가 보다 효율적이었다. 또한 탈염처리 중 교반 및 가온에 따라 20~30%의 효율증대는 확인되었지만, 추가기법적용을 위한 에너지사용과 물리화학적 충격에 의한 유물손상의 위해성을 종합적으로 고려한다면 교반 및 가온에 따른 효율증대는 크지 않은 것으로 판단된다.