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Camphene/WO<sub>3</sub>-NiO 슬러리의 동결건조 및 수소분위기 열처리에 의한 W-Ni 다공체 제조
박성현,박성민,박소정,박보영,오승탁,Park, Sung Hyun,Park, Seong-Min,Park, So-Jeong,Park, Bo-Yeong,Oh, Sung-Tag 한국재료학회 2018 한국재료학회지 Vol.28 No.2
The present study demonstrates the effect of raw powder on the pore structure of porous W-Ni prepared by freeze drying of camphene-based slurries and sintering process. The reduction behavior of $WO_3$ and $WO_3-NiO$ powders is analyzed by a temperature programmed reduction method in Ar-10% H2 atmosphere. After heat treatment in hydrogen atmosphere, $WO_3-NiO$ powder mixture is completely converted to metallic W without any reaction phases. Camphene slurries with oxide powders are frozen at $-30^{\circ}C$, and pores in the frozen specimens are generated by sublimation of the camphene during drying in air. The green bodies are hydrogen-reduced at $800^{\circ}C$ and sintered at $1000^{\circ}C$ for 1 h. The sintered samples show large and aligned parallel pores to the camphene growth direction, and small pores in the internal wall of large pores. The strut between large pores, prepared from pure $WO_3$ powder, consists of very fine particles with partially necking between the particles. In contrast, the strut densification is clearly observed in the Ni-added W sample due to the enhanced mass transport in activation sintering.
박성현,정중식,박영수,Park Seong-Hyun,Jeong Jung-Sik,Park Young-Soo 해양환경안전학회 2006 해양환경안전학회지 Vol.12 No.2
여수해만 특정해역 밖의 인근해역은 섬들이 매우 많고 수심이 낮은 해역으로서 한반도의 동 서해안을 운항하는 선박들이 섬 사이의 협소한 해역을 통항하고 있어 잦은 교행이 이루어지고 있다. 또한 이들 선박은 소리도 남단과 욕지도 부근 해역에서 원유 운반선, 광석운반선 및 컨테이너선과 같은 대형선과 만나면서 교통 혼잡도를 가중시키고 있다. 따라서 본 연구에서는 교통의 흐름을 단순화하고, 교차 및 집중 상황을 완화시키기 위한 통항분리대 도입 및 추천항로를 제안한다. In adjacent sea areas of Yeosu, there are many crossing traffics between eastbound and westbound vessels. Traffic congestion is increasing in sea area of east Sori island and near Yokji Island. In this research, we established TSS near Yeokmando Areas and new recommended route which connected to Seopdo west recommended route to reduce meeting traffic between eastbound vessels and westbound vessels.
두 개의 뜨거운 원형 실린더가 존재하는 사각형 실린더 내부의 자연대류에 관한 수치적 연구
박성현(Seong Hyun Park),박용갑(Yong Gap Park),하만영(Man Yeong Ha),윤현식(Hyun Sik Yoon),손창민(Chang Min Son) 대한설비공학회 2012 설비공학 논문집 Vol.24 No.3
Numerical calculations are carried out for the natural convection in a square enclosure with two hot cylinders induced by temperature difference between a cold outer rectangular cylinder and two hot circular cylinders. A two-dimensional solution for unsteady natural convection is obtained, using the immersed boundary method (IBM) to model two inner circular cylinders based on finite volume method, for different Rayleigh numbers varying over the range of 10³ to 10?. The study goes further to investigate the effect of the location of two cylinders on the heat transfer and fluid flow. The location of inner circular cylinders is changed vertically along the center-line of square enclosure. The changes of heat transfer quantities have been presented.