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3 차원 유체역학 집속에 대한 채널 형상 및 유동 조건의 매개변수 연구
한경섭(Kyungsup Han),김동성(Dong Sung Kim) 대한기계학회 2010 大韓機械學會論文集B Vol.34 No.1
최근 본 연구그룹은 국소적인 종횡비 증가를 기반으로 수평 분리벽 없이 검체의 3 차원 집속을 구현하는 3 차원 유체역학 집속 미세유체 장치(3D-HFMD)를 제안한 바 있다. 본 논문에서는, 다양한 형상 및 유동 조건에 따른 3D-HFMD 의 3 차원 유체역학 집속 거동 영향에 대한 연구를 수행하였다. 이에 3 차원 전산유체역학(CFD) 시뮬레이션을 통해, 형상 및 유동 조건 변화에 대한 기존의 미세유체 장치와 본 연구 그룹이 제안한 3DHFMD의 3 차원 유체역학 집속의 매개변수 연구를 수행하였다. 수행된 CFD 시뮬레이션 결과를 바탕으로 3 차원 집속을 위한 채널 형상 디자인 및 유동 조건을 제안하였다. In our previous work, 3-dimensional hydrodynamic focusing microfluidic device (3D-HFMD) has been developed with the help of locally increased aspect ratio of thickness to width without any horizontal separation wall. In this study, we have investigated 3-dimensional hydrodynamic focusing behaviors inside the 3D-HFMD according to the various geometric and flow conditions. The parametric study has been extensively carried out for the effects of geometric and flow conditions on 3-dimensional hydrodynamic focusing with both 3D-HFMD and previous microfluidic device design based on three-dimensional computational fluid dynamics (CFD) simulations. The CFD simulations suggested the proper design window of channel geometry and flow conditions.
김영찬(Kim, Young-Chan),정진화(Chung, Chin-Wha),이응채(Lee, Eung-Chae),전중환(Chun, Ch.-H.),한경섭(Han, Kyung-Seop),김용환(Kim, Yong-Whan) 한국신재생에너지학회 2006 한국신재생에너지학회 학술대회논문집 Vol.2006 No.11
As the needs of wind energy increase, the more sites for the wind farm are required. As a part of searching for the prominent wind farm site, specially for offshore wind farm, we chose 4 sites along the southern part seashore of JeonNam province based on the analysis of the data gathered by meteorological observatory ud have gathered wind data for more than a year by use of 40m Met masts installed in the representative locations, ie. small islands of 4 different bay area. The siting for the Met masts were very limited by the geographical circumstances The wind data of those areas show a little lower annual average wind speeds, for the wind farm development, of 4m/s to 5.5m/s at the height of 40m above the ground level of the respective islands. The detail figures of one year wind data of those area are presented in this report.
김창삼,한경섭,김신우,Kim, Chang-Sam,Han, Kyong-Sop,Kim, Shin-Woo 한국결정성장학회 2005 한국결정성장학회지 Vol.15 No.2
본 연구에서는 질화규소의 소결 과정에서 인위적으로 형성시킨 기공내부에 질화규소의 휘스커를 성장시키는 새로운 방법을 시도하였다. 실험변수로는 기공의 크기, 기공률 및 질소압력을 사용하였다. 기공률이 14vol%와 27vol%로 낮은 경우에는 질화규소 휘스커가 기공내부에 잘 성장되었으나 39vol%와 50vol%로 기공률이 증가된 경우에는 휘스커가 거의 성장하지 않았다. 한편 기공의 크기와 질소압력은 기공내부에 질화규소 휘스커의 성장에 거의 영향을 주지 않았고, 소결과정에 기공 내에 휘스커를 성장시키는 중요한 조건은 고립된 형태의 닫힌 기공을 유지하는 것임을 알았다. In this study a new growing method of silicon nitride whiskers in the inside of large pores made intentionally during the sintering was conducted. Pore size, pore vol%, and nitrogen pressure were used as experimental variables. Silicon nitride whiskers were well grown in the inside of pores with low pore vol% range from 14 to 27 but not grown with high pore vol% such as 39 and 50. On the other hand, pore size and nitrogen pressure did not have any influence on the whisker growth. Therefore the most important factor to grow silicon nitride whisker in the inside of large pores during sintering was to make pores isolated or closed.
Synthesis of samaria doped CeO2 nanosize powders by a hydrothermal process
배동식,박상환,한경섭,Eun-Jung Kim 한양대학교 세라믹연구소 2004 Journal of Ceramic Processing Research Vol.5 No.3
Nanosized Sm2O3-CeO2 powders were prepared under high temperature and pressure conditions by precipitation from metal nitrates with aqueous potassium hydroxide. Spherical shape Sm2O3-CeO2 powders were obtained in the temperature range of 175 oC~185 oC after 6 hours. TEM and X-ray diffraction patterns showed that the synthesized particles were crystalline. The average size and size distribution of the synthesized particles were below 8 nm and narrow, respectively.
수열합성법으로 합성된 나노 Sm<sub>x</sub>Ce<sub>1-x</sub>O<sub>2-2/x</sub> 분말의 수계 분산
배동식,김은정,한경섭,Bae Dong-Sik,Kim Eun-Jung,Han Kyong-Sop 한국재료학회 2005 한국재료학회지 Vol.15 No.2
Dispersion stability of the $Sm_xCe_{1-x}O_{2-2/x}$ nanoparticles, which was produced by hydrothermal process, was studied in aqueous suspension using ESA (Eletrokinetic Sonic Amplitude). The average particle size of the synthesized $Sm_xCe_{1-x}O_{2-2/x}$ at nanoparticles was about $5{\pm}2nm$. The dispersion and rheological behavior of the $Sm_xCe_{1-x}O_{2-2/x}$ nanoparticles aqueous suspension was investigated using $NH_4OH\;and\;HNO_3$ as a disperse agent. The colloidal stability of aqueous suspensions with $Sm_xCe_{1-x}O_{2-2/x}$ nanoparticles at different pH values has been investigated by means of zeta potential, average particle size, and the distribution of synthesized $Sm_xCe_{1-x}O_{2-2/x}$ nanoparticles. The isoelectric point of the $Sm_xCe_{1-x}O_{2-2/x}$ nanoparticles was at pH around 11 and the value of zeta potential was at its maximum near pH 6.5.
압전감지기/작동기를 이용한 복합적층판의 다중모드 진동제어
김문현,강영규,박현철,황운봉,한경섭,Kim, Mun-Hyeon,Gang, Yeong-Gyu,Park, Hyeon-Cheol,Hwang, Un-Bong,Han, Gyeong-Seop 대한기계학회 1996 大韓機械學會論文集A Vol.20 No.10
Multi-model vibration control of laminated composites plates for various fiver orientations has been carried out by making use of piezolectric materials(PZT) as sensors and actuators. Cantilever plate is used as a specimen to test multi-modal vibration supression under random exitation. Impulse technique is applied to determine the natural frequency, the damping ratio(.zeta.) and the modal damping(2.zeta..omega.) of the first bending and the trosion modes. Two independent controllers are implemented to control the two modes simultaneously and established digitally on the basis of the direct negative velocity feedback control with collocated sensor/actuator. Experimental results for various fiber orientations and feedback gains are compared with finite element analysis considering stiffnesses and dampings of piezoeletiric sensors, actuators and bonding layer.
황성식,박상환,한재호,한경섭,김찬목,Hwang, Sung-Sic,Park, Sang-Whan,Han, Jae-Ho,Han, Kyung-Sop,Kim, Chan-Mook 한국세라믹학회 2002 한국세라믹학회지 Vol.39 No.10
차세대 발전 시스템에서 사용되는 고온 가스 필터용 지지층 소재를 제조하기 위하여 용융 Si 침윤 방법으로 기공율이 32∼36%, 주기공 크기가 37∼90 ${\mu}m$ 범위를 갖는 고강도 다공질 반응소결 탄화규소(RBSC)를 개발하였다. 반응소결 탄화규소 다공체의, 최대 파괴강도는 120MPa이었으며, 용융 Si 침윤 방법으로 제조된 반응소결 탄화규소 다공체에서는 SiC 입자 사이에 SiC/Si로 이루어진 기지상이 형성되어 있기 때문에 파괴 강도 및 열충격 특성이 점토 결합 탄화규소 다공체 보다 우수하였다. 반응소결 탄화규소 다공체의 기공율 및 기공 크기는 잔류 Si의 양 및 성형체에 사용한 SiC 입자 크기에 따라 다르게 나타났다. Porous reaction bonded SiC with high fracture strength was developed using Si melt infiltration method for use of the support layer in high temperature gas filter that is essential to develop the next generation power system such as integrated gasification combined cycle system. The porosity and pore size of porous RBSC developed in this study were in the range of 32∼36% and 37∼90 ${\mu}m$ respectively and the maximum fracture strength of porous RBSC fabricated was 120 MPa. The fracture strength and thermal shock resistance of porous RBSC fabricated by Si melt infiltration were much improved compared to those of commercially available porous clay bonded SiC due to the formation of the strong SiC/Si interface between SiC particles. The characteristics of pore structure of porous RBSC was varied depending on the amounts of residual Si as Well as the size of SiC particle used in green body.
PMSG Wind Turbine Simulation under the consideration of real characteristics
심준보(Sim, Junbo),김명호(Kim, Myungho),박기현(Park, Kihyeon),한경섭(Han, Kyungseop) 한국신재생에너지학회 2010 한국신재생에너지학회 학술대회논문집 Vol.2010 No.11
A various algorism has been studied to extract possibly every energy from a wind turbine in conjunction with the increase of concern about wind power system. In order to verify these control algorism, it is essential to make the most similar conditions to the real wind turbine's environment. Therefore, using separately excited DC motor a wind turbine the most similar to the real turbine is simulated. Tower shadow effect and Wind shear effect are considered as well as inertia emulation. For the control of Back-to-Back Converter Vector current control methods and space vector pulse width modulation are used and for reducing THD of grid current LCL filter is considered. This simulation results verified the energy produced by wind all flows into the utility under the consideration of the characteristics of a wind turbine. The result of this paper is expected to be used as a basic material for analyzing the characteristics of the wind turbine generator.