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양형석(H.S. Yang),김동락(D.L. Kim),손송호(S.H. Sohn),임지현(J.H. Lim),최하옥(H.O. Choi),최연석(Y.S. Choi),이병섭(B.S. Lee),정원묵(W.M. Jung),류희석(H.S. Ryoo),황시돌(S.D. Hwang) 대한기계학회 2008 대한기계학회 춘추학술대회 Vol.2008 No.5
A system for the 3-phase 100-m HTS power cable with 22.9㎸/1.25㎄ has been tested at the KEPCO뭩 Gochang power testing center since 2006. The cooling system consists of a liquid nitrogen decompression cooing system with a cooling capacity of 3㎾ at 66K and a closed circulation system of subcooled liquid nitrogen. Heat loads of the KEPCO HTS power cable system for several electrical loads were measured for investigating long-term operating performance such as cooling capacity, heat load, AC loss, temperature stability of the system.
T.A. Gunadi,W.S. Bae,J.H. Lee,H.D. Nguyen,A. Netzhanova,W.S. Ryoo 한국암반공학회 2013 한국암반공학회 학술대회 및 세미나 자료집 Vol.2013 No.3
Shale gas resources have been aggressively sought out for the past few years. The resurfacing and evolution of hydraulic fracturing technology has been triggered by the need to fracture shale-gas in a massive scale. Although the basic ideas for fracturing are similar between conventional fracturing for formation damage mitigation and slickwater fracturing for shale gas, the fluids’ characteristics are much different.Thus, better understanding of slickwater slurry behavior is critical to ensure a successful fracturing job, effective both engineering-wise and economically. This paper presents the results of related studies in the behavior of slickwater slurries. The experiments comprise of a study on fluids’ rheology with a Brookfield Viscometer, and also the observation of the proppant slurries in flowing conditions. The polymers used to make the slickwater slurries composed of polyacrylamides manufactured domestically in Korea. As for proppant, Carboceramics proppant of 20/40 US Mesh and 40/70 US Mesh were used. A parallel-plate setup was designed to model a simplified fracture, and later used to analyze the flow of proppant slurries with different friction reducers, proppant sizes, and proppant concentrations. The slurries were made according to typical designs previously applied in the field. Observation results showed that proppant settling in slickwater does not resemble proppant settling in viscosified gel solutions and that the horizontal transport of proppant relies on the building of proppant beds. Larger proppants tend to quickly form a ‘dune’ near the entrance of the fracture model until it reached an equilibrium height. The flow velocity of the fluids increased over the dune and increased the transport capability of smaller-sized proppant deeper into the fracture. Previous authors have studied that by modifying pumping schedules based on these results, gas production remarkably increased. In light of this, further plans in studying the modification pumping schedules based on this study are underway.
유성열(S.R. Ryoo),김선영(S.Y. Kim),홍찬욱(C.W. Hong) 한국전산유체공학회 2013 한국전산유체공학회 학술대회논문집 Vol.2013 No.10
A heat sink(HS) using heat pipes for electronics systems had been studied. The experimental results indicate that a cooling capacity of up to 500W at an overall temperature difference of 40 can be attainable. The heat sink design for the power semiconductor in the inverter also showed that a computer simulation can predict the most of the parameters involved. To do so, however, the interior temperature distribution had to be verified by experimental results. The current simulation results were close to the experimental results in acceptable range. The simulation study showed that the design of heat sink heat pipe(HSHP) can be a good results to predict the effects of various parameters involved in the optimum design of the inverter to drive motor.