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주병규,김문수,김현구,김동수,김영록,정도환,양재하,박선화,김태승,Ju, Byoung Kyu,Kim, Moon Su,Kim, Hyun Koo,Kim, Dong Su,Kim, Young Rok,Jeong, Do Hwan,Yang, Jae Ha,Park, Sun Hwa,Kim, Tae Seung 한국지하수토양환경학회 2014 지하수토양환경 Vol.19 No.3
In order to study gross alpha analysis method using LSC, the efficiency tests with uranium standard materials were performed and then compared with the GPC method (US EPA 900.0 method) using 15 groundwater samples. For 15 groundwater samples, the average efficiencies of the GPC and LSC method were 7~11% and 90%, respectively. The average precisions of the GPC and LSC method were 16.16% and 6.00%, respectively. Also, The average standard deviations for 15 samples were 7.38 pCi/L and 2.95 pCi/L, respectively. The determination coefficient of the tested results by two methods was 0.9948. As a result, the LSC method tested in this study was applicable for the screening of the gross alpha and showed the advantages in the gross alpha measurement due to the simple measurement procedures.
다공성 매체내 유기용매(DNAPL)의 용해현상시각화 및 정량화 연구
주병규,정승우 유기성자원학회 2008 유기물자원화 Vol.16 No.1
Oils and chlorinated solvents leaking to the subsurface are entrapped in the soil pore and these are called as nonaqueous phase liquids (NAPL). NAPL entrapped in porous media acts as a continuous source for surface and ground water contamination. This study visualized dissolution of trichloroethylene (TCE) entrapped in porous media and quantified the velocity of TCE dissolution using an image analysis technique. As the water velocity increased, the level of dissolution increased. The results imply that a TCE contaminated region having a high infiltration rate and groundwater velocity may result in severe groundwater contamination. Microscopic images of TCE entrapped in porous media showed that TCE present in the preferential flow paths was easily dissoluted into the water phase. However, TCE present in the stagnant flow region was visualized for long time. The results imply that TCE would be still present in the soil if TCE is detected in goundwater.
감마선분광분석기와 액체섬광계수기를 이용한 226Ra 분석법 비교 연구
주병규,김문수,김현구,김동수,조성진,양재하,박선화,김형섭,권오상,김태승 한국분석과학회 2015 분석과학 Vol.28 No.3
The efficiency and applicability of the solid phase extraction disk method in a 226Ra analysis were examined by the gamma ray spectrometer (GRS) method using a Marinelli beaker and the liquid scintillation counter (LSC) method for groundwater. The recovered 226Ra, which was filtered by the solid phase extraction disk, was analyzed using gamma ray spectrometer The disks, which were pretreated for caulking the daughter nuclide, were sealed with polyethylene film. Distilled water was used for the blank value of the 226Ra activity. The recovery values of 214Bi and 214Pb in the solid phase extraction disk, which used 226Ra standard material, were 80% (295.21 Kev) and 104% (351.92 Kev), respectively, which were higher than 75% determined by the LSC. The injection of nitrogen gas into the measuring chamber reduced the interference values by about 10%. The detection limits of the 226Ra activity in a blank sample of 5 L were 0.17~0.40 pCi/L after 80,000 seconds of measuring time. The relationship of the 226Ra activity in the solid phase extraction disk method and in the LSC method in seven groundwater samples showed a correlation coefficient value 0.987, which implies the applicability of the solid phase extraction disk method. The results showed that 226Ra activity in groundwater using the solid phase extraction disk method has the following benefits: simple pretreatment, time saving, high recovery values, a low detection limit, and so on. Compared with the LSC method and the GRS method using the Marinelli beaker for the 226Ra analysis, the solid phase extraction disk method could be useful in groundwater samples with low levels of activities of radionuclides because the method is not restricted by the volume of the sample.
CFD 기반 인공신경망을 이용한 로터 블레이드 에어포일 공력 예측 모델
주병규,김성수,정용수 한국전산유체공학회 2023 한국전산유체공학회지 Vol.28 No.1
Rotor blade analysis and design process typically use airfoil aerodynamic tables with two-dimensional quasi-steady flow assumption. Thus, its performance highly depends on the accuracy of the airfoil table. However, constructing an airfoil table is not trivial for airfoil shape design problems where the number of design parameters significantly increases. In this study, a surrogate model based on artificial neural networks is developed for airfoil aerodynamic tables in rotorcraft applications. The shape of airfoils is parameterized through Class-Shape Transformation(CST) using coefficients of a Bernstein polynomial expansion. The training data is comprised of 530 shapes sampled from perturbations of the CST coefficients around ten baseline airfoils. The aerodynamic coefficients for each shape are calculated using fully-turbulent flow simulations in the subsonic and transonic regimes. The range of angles of attack also includes stall angle to include any nonlinearities in model prediction. Overall, the trained model accurately predicts aerodynamic coefficients of non-trained airfoil shapes. The variation of model accuracy is also analyzed between interpolated and extrapolated spaces.
CFD 기반 인공신경망을 이용한 로터 블레이드 최적 설계 프레임워크 개발
주병규,정용수 한국항공우주학회 2024 韓國航空宇宙學會誌 Vol.52 No.4
본 연구에서는 ANN 모델 기반의 C81 table 자동생성 모듈과 회전익 통합 해석 코드인 PRASADUM 그리고 다목적 유전 알고리즘을 통합하여 로터 블레이드 최적 설계 프레임워크를 개발하였다. 다목적 최적화를 통해 헬리콥터의 제자리 비행과 전진 비행을 모두 고려할 수 있으며, 이를 UH-60A 헬리콥터의 로터에 적용하여 공력 최적화를 수행하였다. 블레이드 끝단의 3개 섹션에 대한 에어포일과 블레이드 비틀림각을 동시에 최적화하였을 때 가장 큰 폭의 공력 성능이 개선됨을 보였으며, 제자리 비행에서 0.95% 전진비 0.3의 전진 비행에서 9.6%의 로터 파워가 감소하였다. 에어포일과 블레이드 비틀림 분포 최적화를 통해 전진부 블레이드 끝단과 영역에 대한 항력이 감소하였고, 이로 인해 로터의 파워가 감소됨을 확인하였다. 또한, 목적함수로 고려한 비행 조건 외에 다른 비행 영역에서도 로터 파워가 감소하였으며, 도출된 로터 블레이드에 대한 분석을 통해 검증을 수행하였다. A framework for optimizing rotor blade design has been developed, incorporating the Artificial Neural Network-based C81 table module, the rotorcraft comprehensive analysis code PRASADUM, and a multi-objective Genetic Algorithm. The design objective is to minimize the main rotor power of the helicopter in both hover and forward flight conditions, with an advance ratio of 0.3. This framework was applied to a UH-60A helicopter, focusing on optimizing the blade twist distribution and three airfoil segments in the outboard region. The resulting blade shape demonstrated a 9.6% power reduction in the forward flight and a 0.95% reduction in hover conditions. Furthermore, it shows favorable rotor power reduction at other advance ratios of forward flight. The significant power reduction in forward flight is primarily attributed to reduced drag on the advancing side near the blade tip and from the root to the mid-span region. Validation of the optimized rotor involved examining aerodynamic characteristics of the rotor blades.
마이크로공극분석기를 이용한 Trichloroethylene의 용해 물질전달계수 산정
주병규,정승우 대한환경공학회 2006 대한환경공학회 학술발표논문집 Vol.2006 No.12
국내·외의 대표적인 토양·지하수 오염물질인 트리클로로에틸렌(TCE)은 토양 공극내 비수용성액체로 존재하면서 토양공기 및 지하수를 오염시키는 오염원이다. 토양공극내 비수용성액체의 정화를 위해 가장 많이 사용하고 있는 방법은 양수처리법(pump-and-treat)이다. 그러나 TCE의 용해도가 비교적 낮고 TCE가 토양공극내 다양한 형태로 분포하고 있는 특성으로 인해 TCE 정화에 많은 시간과 비용이 소요된다. 또한 이러한 점들은 현장 모니터링결과와 지하수모델링결과가 불일치하는 가장 큰 이유에 해당한다. 본 연구에서는 토양공극내 TCE의 존재 형태에 따른 용해특성을 연구하여 TCE의 용해 물질전달계수(Mass transfer rate coefficient)를 산정하고자 하였다. 토양공극내 TCE의 용해특성을 파악하고 정확한 물질전달계수의 산정은 양수처리법의 설계 및 지하수 모델링에 있어 효율적인 설계 및 예측을 위해 필요한 기본정보이다. 마이크로 공극분석기를 통하여 마이크로 공극내 TCE 형태의 변화와 유출수의 농도를 모니터링 하였다. TCE의 용해특성은 유량과 밀접한 관계를 가지고 있었으나, 기존문헌에는 물질전달계수 산정에 계면면적이 차지하는 역할이 매우 적은 것으로 되어 있으나, 본 연구결과 계면면적의 중요성이 확인되었다.