Effects of gap size for parallel 45 degree angled rib turbulators

Park, Jongmyung,Park, Samgyu,Ligrani, Phillip M Emerald Group Publishing Limited 2016 International journal of numerical methods for hea Vol.26 No.6

<P>Purpose - Turbulent air flows within a channel with 45 degrees angled rib turbulators on the top and bottom walls are numerically predicted using the numerical code. For the predictions, a v(2)-f turbulence model (velocity variance scale and elliptic relaxation factor model) is utilized. The paper aims to discuss these issues. Design/methodology/approach - Three different rib arrangements with or without gap are investigated to present information on the effects of gap size on flow structure and heat transfer characteristics. Three-dimensional turbulent transport, and detailed flow structural characteristics are considered to provide new insight into the mechanisms which result in surface heat transfer augmentations. Findings - Compared to the baseline rib arrangement, the numerically predicted results show that the parallel ribs with gap (where the width of the gap is two times of rib height) shows the highest local Nusselt number ratios. This is a result of locally increased vorticity distributions, as well as augmented local magnitudes of mixing, secondary flows, and turbulent transport. Local transport changes are less pronounced when the gap width of gap is 0.5 times of rib height. As a result, associated local and spatially averaged Nusselt number ratios are also lower for this arrangement. Practical implications - Results will give improved heat transfer augmentation technologies. Originality/value - The present investigation provides new information and insight into flow structural characteristics in a channel with rib turbulators, both with and without gaps, especially the mechanisms which result in surface heat transfer augmentations, which are not available in any other existing numerical or experimental investigation.</P>

Geostatistical integration using 2-D electrical resistivity and 3-D gravity methods for detecting cavities in a karst area

Park, Gyesoon,Park, Samgyu,Yi, Myeong-Jong,Rim, Hyoungrae,Cho, Seong-Jun,Kim, Jung-Ho Springer-Verlag 2010 Environmental Earth Sciences Vol.60 No.5

국내 유도분극 탐사의 연구동향

박삼규 ( Samgyu Park ) 한국지구물리·물리탐사학회 2021 지구물리와 물리탐사 Vol.24 No.4

유도분극(Induced Polarization, IP)탐사가 1973년에 국내 학술지에 처음 소개되었으며, 그 이후 석탄 및 금속광상탐사에 응용되기 시작하면서 대학 및 연구기관에서 유한요소법에 의한 IP 모델링 연구와 인공모형 시료의 유도분극반응 측정 기술이 개발되었다. 1980년 중반에 광대역유도분극(SIP) 탐사기가 국내에 도입되면서 실내 측정 및 해석 기술이 개발되었으나 자원산업의 쇠퇴와 더불어 광상탐사 현장에서 널리 활용되지는 못했다. 1990년대에는 IP탐사가 황화광물의 열수광상 및 벤토나이트 광화대 조사와 해수 침입에 의한 지하수 오염지역에 적용된 사례가 있다. 2000년대 들어서면서 IP탐사의 3차원 역해석 기술이 개발되고, 국내외 광물자원확보를 위한 정밀물리탐사 기술이 요구되면서 암석 시료의 SIP 측정 및 현장 탐사 기술이 확보되었으며, 해남지역 금은광상의 광화대 탐사에 적용한 결과 SIP탐사 기술이 황화광물을 포함하고 있는 금속광상탐사에 유용함이 입증되었다. 이러한 IP 탐사는 리튬, 코발트, 니켈과 같은 첨단 산업의 핵심광물 탐사에서 효과적일 것으로 여겨지고, 또한 환경오염과 지반조사 분야에서도 유용할 것으로 기대된다. Induced polarization (IP) was first published in a Korean academic journal in 1973, and it was soon applied to coal and metal ore exploration. Then, in universities and research institutes, IP modeling studies using the finite element approach and experimental studies on IP responses for artificial samples were conducted. In the mid-1980s, the spectral IP (SIP) measurement module was introduced to Korea, and physical scale modeling and inversion approaches were developed. Due to the decline of the mineral resource industry, this method was not actively applied. However, the SIP method was not applied In the 1990s, IP exploration was applied in the investigation of hydrothermal deposits of sulfide minerals and bentonite mineralization zones, as well as to areas where the groundwater was contaminated by intruding seawater. In the 2000s, three-dimensional inversion of the IP approach was developed, and high-precision geophysical exploration was required to secure domestic and overseas mineral resources, so SIP experiments on rock samples and approaches for field exploration were developed. The SIP approach was proven useful for the exploration of metal deposits containing sulfide minerals by applying it to explore the mineralization zone of gold-silver deposits in the Haenam region. The IP method is considered to be effective in exploring critical minerals (lithium, cobalt, and nickel) in high-tech industries. It also is expected to be useful for environmental and geotechnical investigations.

취약대가 존재하는 제방의 누수 탐지를 위한 전기비저항 탐사의 적용성 연구

박삼규(Samgyu Park),김재홍(Jaehong Kim) 한국지반환경공학회 2013 한국지반환경공학회논문집 Vol.14 No.4

댐 및 저수지 제방의 누수현상은 통관 주변에서 주로 일어나며 평상 시에는 제방에 큰 영향을 미치지 않지만, 호우나 장마철과 같이 저수지 수위가 상승하면 제방의 붕괴 위험을 가져온다. 따라서 이러한 수맥과 경로를 조사하는 것은 재해 예방과 제방관리의 측면에서 매우 중요하다. 본 연구에서는 수치적인 방법과 실험적인 방법을 사용하여 통관이 취약대로 작용하는 댐 및 제방에서의 누수현상을 분석하였다. 누수탐지에는 전기비저항 탐사를 사용하여 그 유용성을 검토하였다. 수치해석의 결과에서는 취약대의 크기와 위치에 따라 전극 간격의 설정이 중요함을 보여주었고, 모형제방의 누수실험에서는 전극간격을 0.3m로 쌍극자 배열을 사용하는 것이 가장 좋은 결과를 얻을 수 있을 것으로 판단되었다. 누수현상의 분석을 통하여 댐 및 제방시설물의 누수탐지에 전기비저항 탐사가 유용함을 확인하였다. The water leakage of reservoir embankment usually occurs around channelling pipes, which gives little influence on the embankment in a normal state. However, the embankment can be destroyed when the water level of reservoir increases with heavy rain and the rainy season in summer. Investigating the water vein and its path is therefore very important from the viewpoint of disaster prevention and embankment maintenance. The water leakage in dams and levees where the channelling pipes are working as weak zone was analyzed by using both numerical simulation and experimental method in this study. To detect the water leakage, an electrical resistivity survey was used and investigated for its’ usability. The numerical results show the size and location of weak zone increases the importance of selection of electrode spacing. The leakage experiments of model embankment present the best result is obtained under the conditions of electrode spacing of 0.3m and dipole-dipole array. By studying the water leakage in dams and levees, the electrical resistivity survey is observed it is a very useful method to predict the leakage.

CFD modeling of ventilation ducts for improvement of air quality in closed mines

Jongmyung Park,Samgyu Park,이동길 한국자원공학회 2016 Geosystem engineering Vol.19 No.4

Decommissioned, dead-end mining tunnels or natural caves are employed to investigate new usage in Korea. Ventilation ducts are designed to allow control of flow velocities, mean age of air, and temperatures of blown air. Turbulent air flows within a dead-ended tunnel are theoretically predicted using the numerical code with a κ − ε turbulence model, and 3.5 M hexahedral grids. Three-dimensional turbulent transport, detailed flow structural characteristics, dimensionless temperature, and local mean age of air are considered to provide new insight into the mechanisms needed to design the ventilation duct for tunnels. Time-averaged turbulent flow characteristics, velocity shape path lines, fluid age distributions, and temperature distributions are presented for 5% inlet turbulence intensity and 12 m/s inlet velocity. From CASE1 to CASE6, six different geometries of ventilation duct are used to optimize the design for better air quality. Overall, the numerically predicted results show the air is fresher in the long duct and average temperatures in the tunnel with long ventilation ducts are slightly lower than those in a tunnel with short ducts.

스카른 금속광상 탐사를 위한 광대역 유도분극법 적용성

박삼규 ( Samgyu Park ),신승욱 ( Seung Wook Shin ),손정술 ( Jeong-sul Son ),조성준 ( Seong-jun Cho ) 한국지구물리·물리탐사학회 2016 지구물리와 물리탐사 Vol.19 No.4

광물자원개발에 있어서 탐사 대상이 천부 내지 고품위 광체에서 심부 또는 저품위 광체로 전환됨에 따라 보다 진보된 탐사 기술 개발이 요구되고 있다. 본 연구에서는 스카른 금속광상의 하나인 가곡광산을 대상으로 정밀 탐사가 가능한 광대역 유도분극(spectral induced polarization; SIP)을 이용한 암석시료의 실내 물성 측정과 현장탐사를 수행했다. 또한 실내 측정에서 획득한 암석의 광대역 유도분극 특성과 현장 탐사자료의 역해석 결과를 종합적으로 해석함으로써 스카른 금속광상에 대한 광대역 유도분극 탐사 적용성을 검토하였다. 암상별 광대역 유도분극 특성을 파악하기 위해 기존연구에서 사용된 89개 시료들의 자료를 재평가했다. 현장탐사는 암상의 경계와 스카른 광화대를 평가할 수 있도록 측선을 설정하고, 0.25 Hz 주파수 대역의 자료를 획득하고 역산해석을 수행했다. 광석광물을 수반하고 있는 암석과 스카른 광화대는 낮은 전기비저항 구간을 보이며, 충전성이 높고 음의 위상이 나타났다. 따라서 광대역 유도분극 탐사는 스카른 광상의 광화작용 특성을 해석하는데 유용하다는 것을 알 수 있었다. The development of more advanced geophysical exploration techniques is necessary because the orebodies as yet discovered are increasingly changing in characteristics from shallow/high-grade to deep/low-grade. In this work, laboratory measurement of physical properties of rock samples and a field survey and interpretation of spectral induced polarization (SIP) have been conducted in a skarn metallic deposit, Gagok mine. The purpose of this study is that the applicability of SIP in the exploration of skarn metallic deposits is verified by the comprehensive interpretation between SIP characteristics of rocks obtained from the laboratory measurements and inverted survey results from the field data. In order to understand the SIP characteristics of each lithology, the data of eighty nine rock samples utilized in the previous studies were revaluated. The field survey was carried out using frequency of 0.25 Hz along a survey line designed for intersecting lithological boundaries and evaluating mineralized zones. The mineralized rocks were more conductive (low-resistivity) and capacitive (high-chargeability or strong-phase) than other rocks. Thus, SIP can be one of the very useful tools for the mineral exploration of the skarn deposits.

심부 금속광체 정밀 물리탐사 기술

박삼규(Samgyu Park),김정호(Jung Ho Kim),성낙훈(Nak Hoon Sung),이명종(Myeong Jong Yi),조성준(Seong Jun Cho),손정술(Jeong Sul Son),방은석(Eun Seok Bang) 대한지질학회 2013 대한지질학회 학술대회 Vol.2013 No.10

인공공시체를 이용한 황화광물의 SIP 특성

박미경(Mi Kyung Park),박삼규(Samgyu Park),이명종(Myeong-Jong Yi),김정호(Jung-Ho Kim) 대한지질학회 2013 대한지질학회 학술대회 Vol.2013 No.10

Spectral-induced polarization characterization of rocks from the Handuk iron mine, South Korea

Shin, S. W.,Park, Samgyu,Shin, D. B. Springer-Verlag 2016 Environmental Earth Sciences Vol.75 No.9

<P>Spectral-induced polarization (SIP) using the electrochemical reaction at the interface between mineral particle and groundwater is a powerful tool for the exploration of minerals. However, SIP responses of rocks have not been fully characterized because it is influenced by various petrological properties. In this study, the relationship between SIP responses and the petrological features of representative rocks from skarn deposits was analyzed. For the evaluation of the SIP responses, chargeability and relaxation time of time domain induced polarization (IP) were calculated by an equivalent circuit analysis. Among various circuit models used for the analysis, an existing circuit model was utilized for this study because it sufficiently describes the electrochemical reaction of watersaturated rocks and is more suitable for the analysis of heterogeneous rocks than the other models. The circuit model was found to be appropriate because the normalized root mean square error between the observed values and ones obtained through the model fittings reasonably low, ranging from 4.18 to 0.05 %. The chargeability values of the mineralized rocks were higher than those of the non-mineralized rocks (igneous and carbonates), and the relaxation time was related to the grain size of the magnetite. It was found that the SIP characteristics of the mineralized rocks are dependent on features of the ore minerals. In the non-mineralized rocks, there was little difference in the chargeability, whereas the variation in their relaxation time values was influenced by the feldspar content (sericitization) and the grain size of the calcite (recrystallization). The SIP characteristics of the non-mineralized rocks are considered to be dependent on the grade of the hydrothermal alteration.</P>

가곡 스카른 광상 암석시료의 광대역 유도분극 반응 특성

신승욱(Seungwook Shin),박삼규(Samgyu Park),신동복(Dongbok Shin) 대한지질학회 2013 대한지질학회 학술대회 Vol.2013 No.10