• Title/Summary/Keyword: Collector Method

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A study on the method for calculating the base-collector breakdown voltage of NPN BJT for integrated circuits (집적회로용 NPN BJT의 베이스-컬렉터간 역방향 항복전압 계산 방법에 관한 연구)

  • Lee, Eun-Gu;Lee, Dong-Ryul;Kim, Tae-Han;Kim, Cheol-Seong
    • Proceedings of the KIEE Conference
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    • 2002.11a
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    • pp.137-140
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    • 2002
  • The algorithm for calculating the base-collector breakdown voltage of NPN BJT(Bipolar Junction Transistor) for integrated circuits is proposed. The method for calculating the electric field using the solution of Poisson's equation is presented and the method for calculating the breakdown voltage using the integration of ionization coefficients is presented. The base-collector breakdown voltage of NPN BJT using 20V process obtained from the proposed method shows an averaged relative error of 8.0% compared with the measured data.

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Performance Monitoring Study of Unglazed Transpired Solar Air Heating Module (무창 기공형 태양열 공기 난방 모듈 성능 모니터링 연구)

  • Kang, Eun-Chul;Hyun, Myung-Taek;Lee, Euy-Joon
    • Journal of the Korean Solar Energy Society
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    • v.22 no.1
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    • pp.67-72
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    • 2002
  • Solar Air Systems (SAS) have unique advantages for space heating and tempering ventilation air. Air, unlike water, needs no protection against freezing nor are leaks damaging to the building structure or its contents. In contrast to glazed collector, unglazed steel solar collector may have higher efficiencies over glazed flat collector due to the absence of the glass. Therefore, the monitoring of SAS is so important to evaluate actual performance of SAS for right applications. This study is to provide a testing method with a movable test cell developed in KIER to evaluate the thermal performance of SAS based on international standard method ASHRAE 93-86, "Method of Testing to Determine the Thermal Performance of Solar Collectors". The monitoring tool used advanced technique LabVIEW 6i with portable notebook computer. Sample results have been obtained to access the performance of a reference and a target SAS module. The process and tool introduced here could be used to provide a performance verification data for future implementation study applications.

Determining Optimum Pumping Rates of Groundwater in Ttansum Island Related to Riverbank Filtration

  • Lee, Chung-Mo;Hamm, Se-Yeong;Choo, Yeon-Woo;Kim, Hyoung-Soo;Cheong, Jae-Yeol
    • Journal of Environmental Science International
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    • v.27 no.10
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    • pp.831-844
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    • 2018
  • Riverbank Filtration (RBF) is a kind of indirect artificial recharge method and is useful in obtaining higher-quality source water than surface water when procuring municipal water. This study evaluated optimal riverbank filtered water and the productivity of the radial collector wells on Ttansum Island in the area downstream of the Nakdong River, where Gimhae City is constructing a municipal water plant for the purpose of acquiring high-quality water. The RBF wells are planned to provide water to the citizens of Gimhae City through municipal water works. Groundwater flow modeling was performed with the following four scenarios: (a) 9 radial collector wells, (b) 10 radial collector wells, (c) 10 radial collector wells and two additional vertical wells, and (d) 12 radial collector wells. This study can be useful in determineing the optimum production rate of bank filtrated water not only in this study area but also in other places in Korea.

Evaluation of Well Production by a Riverbank Filtration Facility with Radial Collector Well System in Jeungsan-ri, Changnyeong-gun, Korea (경남 창녕군 증산리 일대 방사집수정을 활용한 강변 여과수 개발량 평가)

  • Lee, Eun-Hee;Hyun, Yun-Jung;Lee, Kang-Kun;Kim, Hyoung-Soo;Jeong, Jae-Hoon
    • Journal of Soil and Groundwater Environment
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    • v.15 no.4
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    • pp.1-12
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    • 2010
  • Well production by a riverbank filtration facility with multi-radial collector well systems in Jeungsan-ri, Changnyeong gun, Korea was evaluated. In this study, the drawdown at collector wells due to pumping and groundwater inflow rates along the horizontal arms of the collector wells were computed through numerical simulations. Sensitivities of the well production to hydraulic conductivity and well flow coefficient, which represents the resistance to the flow from the aquifer to the horizontal arms, were analyzed. Simulation results showed that, with given proposed pumping rate conditions, the drawdown in the caisson exceeded maximum drawdown constraints in the study site and the adjustment of the pumping rate at each well is needed. The drawdown is affected by the hydraulic conductivity of the main aquifer and the well flow coefficient, which means the profound field investigation of the study site is needed to accurately estimate the efficiency of riverbank filtration through radial collector wells.

Improvement of the Performance of Solar Cooling Heating Systems(I) - Dynamic Load Calculation Using TRNSYS and an Optimization of Solar Systems - (태양열에 의한 냉방 및 난방시스템의 성능향상(I) - TRNSYS에 의한 동직열부하 계산과 태양열 시스템의 최적화 -)

  • Kang, Y.T.;Kim, H.K.;Ro, S.T.
    • The Magazine of the Society of Air-Conditioning and Refrigerating Engineers of Korea
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    • v.17 no.6
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    • pp.696-707
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    • 1988
  • This study simulates a typical solar system using the transient simulation program TRNSYS, and calculates the maximum cooling load of the model room of $50m^2$. In this study, energy rate control method is used in calculating a maximum cooling load. On the ground of the maximum cooling load of the model room, the variables that have an effect on the solar collection performance of the solar system are made a selection. Also in this study the trend of the solar collection performance is shown as the variables change. The results show that the variables which have an effect on the collection performance are collector area, collector mass flow rate, collector slope and the volume of storage tank, and the optimal value of Ac/Vt is not constant but varies as the collector area and the collector mass flow rate. Also the results show that for cooling system the optimal value of the collector slope is latitude minus $15^{\circ}$ during the seasonal operations, and twenty percent of the maximum cooling load is saved with the aid of the solar energy.

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Efficiency of a Direct Absorption Solar Collector using Ag Nanofluids Synthesized by Chemical Reduction Method (화학적 환원법으로 제조된 은나노유체를 사용한 직접흡수식 태양열 집열기의 효율)

  • Lee, Seung-Hyun;Park, Yong-Jun;Choi, Tae Jong;Jang, Seok Pil
    • Journal of the Korean Solar Energy Society
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    • v.34 no.5
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    • pp.65-72
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    • 2014
  • In this paper, the water-based Ag nanofluids are synthesized by the chemical reduction method and their extinction coefficients are measured by an in-house developed measurement device. The Ag nanofluids are manufactured by the chemical reduction method with the mixing of silver nitrate ($AgNO_3$) and sodium borohydride ($NaBH_4$) in an aqueous solution of polyvinyl pyrrolidone (PVP). The extinction coefficients of Ag nanofluids are measured by means of the in-house developed apparatus at a wavelength of 632.8nm according to the particle volume fractions. The results show that the extinction coefficient of water-based Ag nanofluids increases with the increase of nanoparticle concentrations. Finally, the temperature field and efficiency of direct absorption solar collector (DASC) are analytically estimated based on the measured extinction coefficient of water-based Ag nanofluids. The results indicate that the direct absorption solar collectors using nanofluids have the feasibility to improve the efficiency of conventional flat-plate solar collectors without using an absorber plate.

An Explicit Free Method for the Garbage Objects in Java-based Embedded System (자바기반 내장형 시스템에서 쓰레기 객체의 명시적 자유화 방법)

  • Bae, Soo-kang;Lee, Sung-young
    • The KIPS Transactions:PartA
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    • v.9A no.4
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    • pp.441-450
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    • 2002
  • As the size of embedded system software increase bigger and bigger, and it's complexity is grower and grower, the usage of dynamic memory management scheme such collector also has been increased. Using the garbage collector, however, inherently lead us performance degradation. In order to resolve this kind of performance problem in the Java based embedded system. we introduce an explicit dynamic memory free method to the automated dynamic memory management environment. which can be performed by a programmer. In the worst case, the prosed scheme shows the same performance as the case of that only garbage collector is working, since the unclaimed garbage objects will eventually be collected later by the garbage collector. In the best case. our method is free from any runtime overhead because the applications can be implemented without any intervention of the garbage collector. Although the proposed method can be facilitated with all the existing garbage collection algorithms, it shows an outperform in the case of mark-and-sweep algorithm.

Uncertainty of Efficiency Equation of Solar Thermal Collectors (태양열 집열기 효율식의 불확도)

  • Lee, Kyoung-Ho;Lee, Soon-Myung
    • 한국신재생에너지학회:학술대회논문집
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    • 2010.11a
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    • pp.65.1-65.1
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    • 2010
  • Thermal performance tests of solar thermal collectors include determination of coefficient parameters in an efficiency equation. The parameters can be estimated using regression method to minimize an objective function as sum of differences between measured efficiency data and regressed efficiency equation. However, this conventional approach doesn't consider measurement uncertainties. In this presentation, a method to determine regression parameters in the efficiency equation and uncertainties of the parameters is described with mainly mathematical expressions based on literature reviews. In the method, parameters in the equation for collector efficiency can be determined using regression analysis with a weighting factor in the objective function. The weighting factor can be uncertainties of the differences between measured and fitted efficiencies. To evaluate the approach, performance estimation of a solar collector using the efficiency equation with uncertainties is compared to the result using the conventional efficiency equation by a simulated way for a case in one of previous studies.

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Design of high speed InAlGaAs/InGaAs HBT structure by Hybrid Monte Carlo Simulation (Hybrid Monte Carlo 시뮬레이션에 의한 고속 InAlGaAs/InGaAs HBT의 구조 설계)

  • 황성범;김용규;송정근;홍창희
    • Journal of the Korean Institute of Telematics and Electronics D
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    • v.36D no.3
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    • pp.66-74
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    • 1999
  • InAlGaAs/InGaAs HBTs with the various emitter junction gradings(xf=0.0-1.0) and the modified collector structures (collector- I;n-p-n, collector-II;i-p-n) are simulated and analyzed by HMC (Hybrid Monte Carlo) method in order to find an optimum structure for the shortest transit time. A minimum base transit time($ au$b) of 0.21ps was obtainsed for HBT with the grading layer, which is parabolically graded from $x_f$=1.0 and xf=0.5 at the emitter-base interface. The minimum collector transit time($\tau$c) of 0.31ps was found when the collector was modified by inserting p-p-n layers, because p layer makes it possible to relax the electric field in the i-type collector layer, confining the electrons in the $\Gamma$-valley during transporting across the collector. Thus InAlGaAs/InGaAs HBT in combination with the emitter grading($x_f$=0.5) and the modified collector-III showed the transit times of 0.87 psec and the cut-off frequency (f$\tau$) of 183 GHz.

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Drying of Red Ginseng by Flat-Plate Solar Collector (평면식(平面式) 태양열집열기(太陽熱集熱機)를 이용(利用)한 홍삼건조(紅蔘乾燥))

  • Chang, Kyu-Seob;Kim, Sang-Dal;Hong, Soon-Keun;Yoon, Han-Kyo
    • Applied Biological Chemistry
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    • v.25 no.3
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    • pp.111-118
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    • 1982
  • A closed solar collector drying system by water exchange was evaluated for the drying of ginseng. The thermal efficiency of solar collector, drying efficiency, drying characteristics and product quality were investigated. The drying period was reduced by one-thirds in comparison with typical method. The maximum and minimum thermal efficiency of the solar collector during drying period were 14.42%, and 4.73%, respectively. The drying efficiency of solar collector and control system showed 28.34%, and 13.45%, respectively; net drying efficiency being 14.8%. The drying rate curve of red ginseng showed only falling rate period, and its equation was $Y=50.7023t.^{-0.4138}$ The brown color intensity of red ginseng was higher in solar collector drying system than in typical method, and reductivity by diphenyl picryl hydrazil solution in red ginseng extract showed similar result to brown color intensity.

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