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전산유체를 활용한 정수공정에서 전염소 공정 최적설계 방안
조영만 ( Young Man Cho ) 한국수처리학회 2013 한국수처리학회지 Vol.21 No.5
Pre-chlorination process is the first step in portable water process in order to oxidize such as algae, bacteria, organic matter, iron and manganese. In addition, It is may be used to prevent the growth of organisms within the water intake facilities and an water treatment facilities. Thus, depending on the purpose of pre-chlorination, chlorine injection point and how careful design is required. The pre-chlorine can be put at the intake conduit grit chamber, absorbing well of intake pumping station, intake pipe, receiving well. we evaluated most suitable design method of pre-chlorination process by using computational fluid dynamics. The study results, the injection way of chlorine at the intake conduit and pipe is efficient the direct pipe than perforated pipe. Also, mixing length of injected chlorine is four times of pipe diameter. The method of pre-chlorination injection in grits chamber is efficient the perforated pipe. Uniformity of effluent amount at the each hole is inversely proportional to the area ratio. Efficient injection way of chlorine within absorbing well of intake pumping station is the direct pipe than the perforated pipe. chlorine injection pipe should ensure a sufficient distance from the operating pump. The gap between the operating pump and the other is the shorter the better. The optimal depth of the injection pipe is between middle depth and inflow pipe of pump.
조영배(Young-Bae Cho),손호익(Ho-Ik Son),김학만(Hak-Man Kim),곽주식(Joosik Kwak),안용호(Yong-Ho An) 대한전기학회 2014 전기학회논문지 Vol.63 No.11
VSC-HVDC system is vulnerable to a DC fault because the fault current can be injected from AC system to DC system during the fault. Therefore, DC circuit breaker is required to isolate faults in VSC-HVDC system. The inverse current injection method of circuit breaker has been considered as DC circuit breaker. However, the topology has drawback that the breaking time is longer than hybrid circuit breaker using semiconductor devices. In order to solve this problem, this paper proposes an improved topology of circuit breaker based on inverse current injection method . In addition, the proposed topology will be compared with the existing topology. And we will verify its effects by using the simulation results.
전산유체역학을 활용한 유공관 최적설계 및 맥동식침전지 수리평가
조영만 ( Young Man Cho ) 한국수처리학회 2013 한국수처리학회지 Vol.21 No.4
The pulsator clarifiers is very sensitive about the changing of the water quantity. So the most important part of pulsator clarifiers is the perforated pipe for to drain the raw water with equal pressure and velocity. First, we evaluated the design parameters of the common perforated pipe. The uniformity of outflow from the perforated pipe is directly affected according to area ratio. In other words, the uniformity of outflow is improved as area ratio is smaller. Also, at the same area ratio, the uniformity of outflow is improved as number of holes is increase. Specially, in case of the two holes per length of pipe diameter(2/D) shows the most uniformity of outflow and the best hydraulic with the smaller pressure drop. Second, we evaluated the pulsator clarifiers that has installed and operated in H water treatment plant. Results, it was designed properly that the ratio of cross section between pipe and holes is 8.9%. But the distance of each holes should be improved to 2/D of the optimal value from 1.3/D. The standard deviation of distributed quantity from the middle channel to the hole pipe was 0.12 and from the hole pipe to holes was 0.04.
조영만,정영식,Cho, Young-Man,Jeung, Young-Sik 한국식품영양학회 2019 韓國食品營養學會誌 Vol.32 No.5
This study compares and analyzes inorganic components of four different Pu-erh tea species consumed in Korea. The criteria for the inorganic components was based on the Royal Institute of Technology (KTH) recommendations. Out of the 19 general items: potassium, manganese, silicon and fluorine were detected in amounts exceeding the maximum allowable concentration by 5~23, 57~91, 1.6~1.8 and 9~18 times respectively. Out of the 15 potentially harmful elements: aluminum and nickel were exceeded the Maximum allowable concentration by 9~14 times and 0.8~1.2 times respectively. To reduce the concentration of inorganic elements in excess of the maximum allowable concentration, the extraction time of tea should be less than 1 minute in addition to limiting the amount. The amount of Pu-erh tea for extraction was about 0.1 g manganese, about 0.3 g potassium, about 0.5 g fluoride and about 2 g silicon. Therefore, the maximum amount of tea for extraction should be 0.1 g in regards to the safety of Pu-erh tea. Based on the recommended maximum daily intake of inorganic ingredients by the Ministry of Food and Drug Safety, it is desirable that the number of extractions be less than three.
전산유체역학(CFD)를 활용한 정수공정에서 압력수 확산공정 진단
조영만(Young Man Cho),유수전(Soo Jeon Yoo),노재순(Jae Soon Roh),빈재훈(Jae Hoon Bin),최광주(Kwang Ju Choe),이광욱(Kwang Ug Lee),이기봉(Gi Bong Lee),이정규(Jeong Gyu Lee) 大韓環境工學會 2011 대한환경공학회지 Vol.33 No.5
압력수 확산공정은 정수공정에서 응집제나 염소용해수를 고압의 압력수로 분사하여 혼합하는 공정이다. 본 연구의 목적은 압력수 확산공정에 대한 전산유체역학적(Computational Fluid Dynamics) 진단을 통해 투입한 약품의 완전 혼합거리 및 혼합 거리를 줄이기 위한 확산판의 크기와 설치거리를 도출하는 것이다. 진단결과 2,200 mm 대형관에 5 kg/cm2 압력수를 50 mm, 100 mm 분사관으로 분사할 경우 혼합이 완료되는 혼합거리는 4D였다. 혼합거리를 줄이기 위해 분사관 전방에 확산판을 설치할 경우 분사관이 50 mm일 때 0.1D 직경의 확산판을 분사관 전방 0.2D 거리에 설치하면 혼합거리를 3D로 줄일 수 있다. 그러나 분사관이 100 mm인 경우는 확산판의 크기와 설치 거리와는 상관없이 확산판이 없는 4D보다 확산거리를 줄일 수 없는 것으로 진단되었다. 따라서 2,200 mm 관에 압력수를 분사하는 경우는 50 mm 분사관을 설치하는 것이 100 mm보다 휠씬 효율적인 것으로 나타났다. The Process of Pressurized water diffusion is mixing process by pressurized water injection with coagulate and chlorine water in the water treatment system. The objectives of this research were to evaluate the mixing length and diameter of diffusion plate and distance from injection pipe for complete mixing by using computational fluid dynamics. From the results of CFD simulation, when diameter of injection pipe is 50 mm, 100 mm and injection pressure is 5 kg/cm2 and the diameter of inlet pipe is 2,200 mm, the complete mixing length is 4D (D: Length as diameter of inlet pipe). When diameter of injection pipe is 50 mm, the diameter of the diffusion plate in o.1D and distance from injection pipe is 0.2D, the complete mixing length is 3D that is the most short mixing length. But when diameter of injection pipe is 100 mm and mutually related the diameter, distance of diffusion plate, the complete mixing length is 4D over. Therefore, as the diameter of inlet pipe is 2,200 mm, the injection pipe 50 mm is more efficient than 100 mm.
CFD를 활용한 수처리공정 대형관에서 압력수 혼합공정 평가
조영만 ( Young-man Cho ),유현철 ( Hyun-chul Yu ),장경혁 ( Gyeong-hyuk Jang ),정용준 ( Yong-jun Jung ) 한국물환경학회(구 한국수질보전학회) 2021 한국물환경학회지 Vol.37 No.3
Mixing is a very important unit in water treatment process. A mechanical stirring method is generally used for mixing, but recently, the use of pressurized water mixing method (pump diffusion flash mixer) has gained interest because it is more advantageous in terms of mixing time, noise, energy consumption, and maintenance. The following conclusions were obtained from the study of pressurized water mixing method by Computational Fluid Dynamics. Firstly, the mixing degree in the pipe increased as the density of water increased. Secondly, even if the relative velocity between flow rate in the pipe and the pressurized water was constant, the mixing degree decreased as the flow velocity in the pipe increased. Thirdly, the stronger the injection energy the higher the mixing degree. It was also found that the mixing degree was greatly affected by the injection velocity as compared to the injection flow amount. Finally, the required energy to achieve 95% mixing degree at the distance of 10 times diameter in big pipes of 500 mm to 3000 mm was 0.3 to 4.5 kJ. The result of this study could be used in the process design of injection with water purification chemicals, such as, ozone, chlorine, and coagulant.