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전호환,김문찬,이인원,김국현,Jung Kwan Lee,정광효 대한조선학회 2012 International Journal of Naval Architecture and Oc Vol.4 No.4
The stern boat deployment system was investigated to evaluate the capability of launching and reco¬vering rigid hull inflatable boat (RHIB) via the stern ramp. The main parameters to launch and recover RHIB were tested at the design stage. The combined hydrodynamic effect of the stern wake and the water jet flow made it difficult to maintain the maneuvering and sea-keeping ability of RHIB approaching to the stern ramp. The safe recovery course was proposed to maintain the directional control of RHIB and to reduce the combined hydrodynamic effect in the transom zone. To evaluate the fea¬sibility of RHIB recovery, the stern sill depth was measured in various conditions and the ramp availability time was obtained. Also, the experimental percent time operability (PTO) test was performed by the number of successive launching and recovering operations.
지하수면하에서 이동하는 2차원 수중익의 조파저항 및 양력계산
전호환,박일룡 釜山大學校 生産技術硏究所 1994 生産技術硏究所論文集 Vol.47 No.
본 연구는 자유수면하에서 이동하는 2차원 수중익의 자유수면의 영향으로 발생하는 유동문제를 특이점분포 포텐셜이론을 바탕으로 해석하였다. 수면위 일정거리의 위치에 Rankine소오스를 분포시키고, 수중익의 camber line에 소오스와 보텍스를 분포하여 경계조건식, Kutta-Joukowski 및 Lagally정리들로 부터 파고, 양력과 조파저항을 구했다. 자유수면의 영향을 고려해주기 위해 Kelvin해로부터 출발하여 조파문제의 지배경계조건을 엄밀히 만족하도록 iteration을 통하여 계산정도를 높이도록 하였다. 잠수깊이 변화에 따른 파형의 변화가 Duncan의 실험결과와 비슷함을 보였다. 높은 Froude number에서의 양력과 항력을 계산하여 Nakatake의 수치계산 결과와 비교하였다. 고속에서의 수중익에 대한 발표된 실험결과가 없기 때문에 앞으로 이에 대한 실험적 연구가 필요하며 이는 수치해석 결과의 검증에도 효과적으로 쓰여질 수 있다고 본다. Flow characteristics of a hydrofoil running under the free surface are investigated based on potential theory using singularity distribution techniques. In order to generate wave elevation, Rankine sources are distributed at a distance above the undisturbed free surface. Sources and vortices are distributed on the mean camber line of a foil to account for the thickness and lift. From the free surface boundary condition, Kutta-Joukowski theorem and Lagally theorem, wave elevation, lift force and wave resistance are calculated. It is shown that the calculated wave elevations of a NACA0012 foil is very sitnilar to those of Duncan's experimental results. The wave resistance and lift force of a NACA0012 at high speeds are calculated and compared with Nakatake's numerical results. Since there are no published experimental results available for hydrofoils at higher speeds, it is expected that experimental investigations at higher speeds are desirable.
전호환,조완근 한국공업화학회 2014 Journal of Industrial and Engineering Chemistry Vol.20 No.3
Polymer-supported TiO2 nanofibers with different polyvinylpyrrolidone (PVP)-to-TiO2 (PT) ratios weresynthesized and their photocatalytic efficiencies were examined for the decomposition of trichloroeth-ylene (TCE). The spectral results of the TiO2 nanofibers confirmed the presence of TiO2 crystal phases inthe nanofibers. The TiO2 nanofiber with the highest PT ratio of 1:1.3 showed the highest TCEdecomposition (94%), followed by TiO2 nanofibers with PT ratios of 1:0.7 (91%), 1:0.35 (88%), and 1:0.1(84%). The conditions of low input concentration and humidity were suggested for the optimaldecomposition of TCE. Consequently, the TiO2 nanofiber webs could be used effectively to decomposeTCE.
Application of a divided wall column for gas separation in floating liquefied natural gas plant
전호환,김영한 한국화학공학회 2013 Korean Journal of Chemical Engineering Vol.30 No.7
A divided wall column (DWC) has widely been utilized as an energy-efficient distillation column. When it is applied to the offshore floating liquefied natural gas (FLNG) plant, its compactness can provide a favorable distillation system for the unconventional plant on top of its high energy efficiency. We investigated the design characteristic, cost evaluation and operation difficulty of the DWC at its utilization in the FLNG plant. The results from the HYSYS simulation of the DWC were compared with those of the conventional distillation system, and the following was found from the study. The DWC replacing the depropanizer and debutanizer of the conventional distillation system requires 12.5%less investment cost. While the saving of 25% in steam cost is expected from the DWC, the total utility cost including the refrigerant cost is reduced by 20.2% due to the lower cost reduction of refrigeration in the DWC.