• Title/Summary/Keyword: 로 유량

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Seasonal Variability of Thermal Structure and Heat Flux in the Juam Reservoir (주암호의 계절별 수온 구조와 열수지 변화)

  • Sun, Youn-Jong;Cho, Cheol;Kim, Byong-Chun;Huh, In-Aa;Yoon, Jun-Heon;Chang, Nam-Ik;Cha, Sung-Sik;Cho, Yang-Ki
    • Korean Journal of Ecology and Environment
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    • v.36 no.3 s.104
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    • pp.277-285
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    • 2003
  • Temperature profiles were observed to understand seasonal variation of thermal structures in the Juam reservoir from March 2000 to May 2001. Heat flux which affects thermal structures was calculated by observed water temperature and meteorological data. Temperature became homogeneous vertically by convection due to the surface cooling in winter. Maximum heat loss through the surface (109.45W/$m^2$) occurred in December. There was a horizontal gradient of water temperature in winter. The temperature was $3^{\circ}C$ at upstream and $5^{\circ}C$ near the dam. The surface temperature increased by the increase of solar radiation in spring and summer. Maximum heat gained through the surface was 101.95 W/$m^2$ in July. Maximum surface temperature was $29^{\circ}C$ in August, whereas the bottom water was $7^{\circ}C.$ Surface mixed layer became thicker and its temperature decreased by surface heat loss in fall and winter.

Heat Penetration Characteristics and Keeping Quality of Retort Pouched Curry (레토르트 파우치 카레의 전열특성 및 품질안정성)

  • Koo, Bon-Youl;Park, Seong-Joon;Byeon, You-Ryang;Son, Se-Hyeong
    • Korean Journal of Food Science and Technology
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    • v.25 no.1
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    • pp.63-68
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    • 1993
  • Heat penetration characteristics of retort pouched curry were studied to determine optimal sterilization conditions. Heating curve of retort pouched curry showed a simple logarithmic curve. The $f_h$ value (min.) of solid part in retort pouched curry was 1 min. higher than that of liquid part. $f_h$ value (min.) and $j_h$ value (heating lag factor) ranged from 8.3 min. to 12 min. and 1.0 to 1.17 respectively with increasing the ratio of solid to liquid and viscosity. $f_h$ value (min.) and $j_h$ value were significantly increased from 7.4 min. to 12.6 min. and 1.0 to 1.14 respectively with increasing thickness of the pouch from 11 to 15 mm. The low and medium volatile aroma components of retort pouched curry decreased during sterilization, which increased the high volatile aroma components. The retort pouched curry processed at $120^{\circ}C$, for 24 min. with $F_o$, value of $8{\sim}9$ could keep up a desirable quality without any remarkable deterioration.

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A Study on the Effect of Sulfur Content in Fuel Oil on the Emission of Air Pollutants According to Operating Conditions of Small Ship Engines (선박용 소형 엔진에서 연료유 내 황 함유량이 운전 조건에 따라 대기오염물질 배출에 미치는 영향에 관한 연구)

  • Lee, Kyeong-yeol;Rho, Beom-seok;Lee, Won-Ju;Choi, Jae-hyuk
    • Journal of the Korean Society of Marine Environment & Safety
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    • v.24 no.6
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    • pp.834-840
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    • 2018
  • In this study, the characteristics of air pollutant emissions from ships' engines have been investigated by conducting E2 and E3 cycle mode tests. A engine 360Ps (Doosan L126TIH engine) and 400kW dynamometer Horiba-Schenck were utilized for engine tests. The FTIR analyzer and SPC were used to measure exhaust gas (NOx, SOx etc.) and PM (particulate matter), respectively. The results showed that the emissions of THC and CO produced from engine were increased with the increase of sulfur content in fuel oils at E2 and E3 cycle modes. The kinetic viscosity of the fuel increased as the sulfur content of the fuel increased, thereby the specific fuel oil consumption (SFC) of the engine improved. This result is considered to be due to improved combustion conditions due to increased average diameters of sprayed particles and due to increased kinetic viscosity under constant fuel injection pressure in this study. In the case of NOx emission, this study showed no significant change in amount of sulfur content.

Reduction of gate leakage current for AlGaN/GaN HEMT by ${N_2}O$ plasma (${N_2}O$ 플라즈마에 의한 AlGaN/GaN HEMT의 누설전류 감소)

  • Yang, Jeon-Wook
    • Journal of IKEEE
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    • v.11 no.4
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    • pp.152-157
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    • 2007
  • AlGaN/GaN high electron mobility transistors (HEMTs) were fabricated and the effect of ${N_2}O$ plasma on the electrical characteristics of the devices was investigated. The HEMT exposed to ${N_2}O$ plasma formed by 40 W of RF power in a chamber with pressure of 20 mTorr at a temperature of $200^{\circ}C$, exhibited a reduction of gate leakage current from 246 nA to 1.2 pA by 10 seconds treatment. The current between the two isolated active regions reduced from 3 uA to 7 nA and the sheet resistance of the active layer was lowered also. The variations of electrical characteristics for HEMT were occurred within a short time expose of 10 seconds and the successive expose did not influence on the improvements of gate leakage characteristics and conductivity of the active region. The reduced leakage current level was not varied by successive $SiO_2$ deposition and its removal. The transconductnace and drain current of AlGaN/GaN HEMTs were increased also by the expose to the ${N_2}O$ plasma.

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Freshwater Fish Fauna and Distribution in Kojedo, Korea (거제도의 담수어류상과 분포상의 특징)

  • Son, Yeong-Mok;Song, Ho-Bok
    • Korean Journal of Ichthyology
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    • v.10 no.1
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    • pp.87-97
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    • 1998
  • The freshwater fish fauna and distribution were investigated in Kojedo from 1982 to 1997. The collected fishes were classified into twenty four species of ten families. Dominant species was Zacco temmincki (relative abundance: 18.1%) and subdominant species was Rhinogobius brunneus (16.4%). Also Iksookimia longicorpus (12.3%), Oryzias latipes (7.5%), Chaenogobius urotaenia (7.5%) and Carassius auratus (6.9%) were numerous. The endemic species of Korea were six species (25.0%) and endangered species were C. splendidus, S. microdorsalis and C. kawamebari. In this study, species diversity index was high at Yoncho stream, dominance index at Aju and Oaepo stream and evenness index at Oaepo stream in community structure. There was a tendency of fish distribution in Kojedo that more longer the stream and more larger the water volume were, there were more species and more individual numbers. It was considered that the dominance of upper and middle reach dwelling fishes resulted in the dominance of Aa type stream mainly. Liobagrus mediadiposalis and L. mediadiposalis ssp. 1 showed different distribution pattern in Kojedo : that is, the former inhabited in east-northern part but the latter in south-western part separately. And the importance of this distribution pattern was discussed in relation to paleogeography.

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c-BN 박막의 박리현상에 미치는 공정인자의 영향

  • 이성훈;변응선;이건환;이구현;이응직;이상로
    • Proceedings of the Korean Vacuum Society Conference
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    • 1999.07a
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    • pp.148-148
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    • 1999
  • 다이아몬드에 버금가는 높은 경도뿐만 아니라 높은 화학적 안정성 및 열전도성 등 우수한 물리화학적 특성을 가진 입방정 질화붕소(cubic Boron Nitride)는 마찰.마모, 전자, 광학 등의 여러 분야에서의 산업적 응용이 크게 기대되는 자료이다. 특히 탄화물형성원소에 대해 안정하여 철계금속의 가공을 위한 공구재료로의 응용 또한 기대되는 재료이다. 특히 탄화물형성원소에 대해 안정하여 철계금속의 가공을 위한 공구재료로의 응용 또한 크게 기대된다. 이 때문에 각종의 PVD, CVD 공정을 이용하여 c-BN 박막의 합성에 대한 연구가 광범위하게 진행되어 많은 성공사례들이 보고되고 있다. 그러나 이러한 c-BN 박막의 유용성에도 불구하고 아직 실제적인 응용이 이루어지지 못한 것은 증착직후 급격한 박리현상을 보이는 c-BN 박막의 밀착력문제때문이다. 본 연구에서는 평행자기장을 부가한 ME-ARE(Magnetically Enhanced Activated Reactive Evaporation)법을 이용하여 c-BN 박막을 합성하고, 합성된 c-BN 박막의 밀착력에 미치는 공정인자의 영향을 규명하여, 급격한 박리현상을 보이는 c-BN 박막의 밀착력 향상을 위한 최적 공정을 도출하고자 하였다. BN 박막 합성은 전자총에 의해 증발된 보론과 (질소+아르곤) 플라즈마의 활성화반응증착(activated reactive evaporation)에 의해 이루어졌다. 기존의 ARE장치와 달리 열음극(hot cathode)과 양극(anode)사이에 평행자기장을 부여하여 플라즈마를 증대시켜 반응효율을 높혔다. 합성실험용 모재로는 p-type으로 도핑된 (100) Si웨이퍼를 30$\times$40 mm크기로 절단 후, 100%로 희석된 완충불산용액에 10분간 침적하여 표면의 산화층을 제거한후 사용하였다. c-BN 박막을 얻기 위한 주요공정변수는 기판바이어스 전압, discharge 전류, Ar/N가스유량비이었다. 증착공정 인자들을 변화시켜 다양한 조건에서 c-BN 박막의 합성하여 밀착력 변화를 조사하였다. 합성된 박막의 결정성 분석을 FTIR을 이용하였으며, Bn 박막의 상 및 미세구조관찰을 위해 투과전자현미경(TEM;Philips EM400T) 분석을 병행하였고, 박막의 기계적 물성 평가를 위해 미소경도를 측정하였다. 증착된 c-BN 박막은 3~10 GPa의 큰 잔류응력으로 인해 증착직후 급격한 박리현상을 보였다. 이의 개선을 위해 증착중 기판바이어스 제어 및 후열처리를 통해 밀착력을 수~수백배 향상시킬 수 있었다. c-BN 박막의 합성을 위해서는 증착중인 박막표면으로 큰 에너지를 갖는 이온의 충돌이 필요하기 때문에 기판 바이어스가 요구되는데, c-BN의 합성단계를 핵생성 단계와 성장 단계로 구분하여 인가한 기판바이어스를 달리하였다. 이 결과 그림 1에서 나타낸 것처럼 c-BN 박막의 핵생성에 필요한 기판바이어스의 50% 정도만을 인가하였을 때 잔류응력은 크게 경감되었으며, 밀착력이 크게 향상되었다.

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Development of Flood Control Effect Index by Using Fuzzy Set Theory (Fuzzy 집합 이론을 이용한 홍수조절효과 정량화 지표 개발)

  • Kim, Juuk;Choi, Changwon;Yi, Jaeeung
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.31 no.5B
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    • pp.415-429
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    • 2011
  • Quantitative evaluation indexes for flood control effect of a multi-purpose reservoir used widely in Korea are the discharge control rate, reservoir release rate, reservoir storage rate, and flood control storage utilization rate. Because these indexes usually use and compare inflow, release, and storage data directly, the uncertainties included in these data are not considered in evaluation process, and the downstream flood control effects are not assessed properly. Also, since the acceptable partial failure in a design of water resources system is not considered, the development of a new flood control effect evaluation index is required. Fuzzy set theory is therefore applied to the development of the index in order to consider the data uncertainty, the downstream flood control effect, and the acceptable partial failure. In this study, the flood control effect of a multi-purpose reservoir is evaluated using the flood control effect index developed by applying fuzzy set theory. The Chungju reservoir basin was selected as a study basin and the storm events of July, 2006 are used to study the applicability of the developed index. The related factors for flood control effect are fuzzified, the acceptable failure region is divided from the system state to evaluate the flood control effect using developed flood control effect index. The flood control effect index were calculated by applying to the study basin and storm events. The results show that the developed index can represent the flood control effect of a reservoir more realistically and objectively than the existing index.

Analysis of Hydraulic Characteristics of Flood Plain Using Two-Dimensional Unsteady Model (2차원 부정류 모형을 이용한 둔치의 수리특성 분석)

  • Ku, Young Hun;Song, Chang Geun;Kim, Young Do;Seo, Il Wo
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.33 no.3
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    • pp.997-1005
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    • 2013
  • Since the cross-sectional shape of the Nakdong river is compound type, the water stage rises up to the top of the flood plane, as the flow discharge increases during the extreme rain storm in summer. The recent increase of rainfall intensity and flood frequency results in the immersions of parks and hydrophilic facilities located in the flood plain. Therefore it is necessary to analyze the hydraulic characteristics evolved by the extreme rain storm in the flood plain. The study reach ranging from the Gangjeong Goryeong Weir and the Dalseong Weir, where several hydraulic facilities are located along the channel, was selected and numerical simulations were conducted for 42 hours including the peak flood of the typhoon Sanba. The 2-D transient model, FaSTMECH was employed and the accuracy of the model was assessed by comparing the water level between the simulation results and the measured ones at a gauging station. It showed a high correlation with $R^2$ of 0.990, AME of 0.195, and RMSE of 0.252. In addition, the inundation time, the inundation depth, the inundation velocity, and the shear stress variation in the flood plain facilities were analyzed.

The Effect of Uncertainty in Roughness and Discharge on Flood Inundation Mapping (조도계수와 유량의 불확실성이 홍수범람도 구축에 미치는 영향)

  • Jung, Younghun;Yeo, Kyu Dong;Kim, Soo Young;Lee, Seung Oh
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.33 no.3
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    • pp.937-945
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    • 2013
  • The accuracy of flood inundation maps is determined by the uncertainty propagated from all variables involved in the overall process including input data, model parameters and modeling approaches. This study investigated the uncertainty arising from key variables (flow condition and Manning's n) among model variables in flood inundation mapping for the Missouri River near Boonville, Missouri, USA. Methodology of this study involves the generalized likelihood uncertainty estimation (GLUE) to quantify the uncertainty bounds of flood inundation area. Uncertainty bounds in the GLUE procedure are evaluated by selecting two likelihood functions, which is two statistic (inverse of sum of squared error (1/SAE) and inverse of sum of absolute error (1/SSE)) based on an observed water surface elevation and simulated water surface elevations. The results from GLUE show that likelihood measure based on 1/SSE is more sensitive on observation than likelihood measure based on 1/SAE, and that the uncertainty propagated from two variables produces an uncertainty bound of about 2% in the inundation area compared to observed inundation. Based on the results obtained form this study, it is expected that this study will be useful to identify the characteristic of flood.

Estimation of Suspended Sediment Concentration in Small Stream with Acoustic Backscatter from Horizontal ADCP based on Real-Scale Field Experiment (실규모 현장 실험 기반 H-ADCP 초음파 산란도 활용 소하천용 하천 부유사 농도 측정 기법 개발)

  • Seo, Kanghyeon;Kim, Dongsu;Son, Geunsoo
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.36 no.6
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    • pp.1023-1035
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    • 2016
  • Suspended sediment concentration (SSC) is a crucial riverine parameter in terms that it can be utilized for analyzing sediment transport, stability assessment of river and structure and so on. However, in case of domestic, sediment discharge data are not enough because of using conventional sediment samplers. This study aimed at developing a practical technique for estimating suspended sediment concentration in high spatial and temporal resolution by building relationship between acoustic backscatter (or SNR) from H-ADCP with actually observed data using LISST-100X. In this regard, a dedicated correction algorithm was proposed particularly for the adapted H-ADCP (SonTek SL-3000). Then, a SNR-SSC relation was built based upon a real-scale field experiment, where both H-ADCP and LISST-100X were concurrently operated to observe SNR and SSC, respectively. The coefficient of determination for the developed regression equation of SNR-SSC relation was around 0.85~0.88, thereby the relation could be evaluated to be highly correlated. The result of this study might be potentially applied for real-time and simultaneous observation of SSC when H-ADCP could be applied.