http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
다점 확률분포 모델을 이용한 초임계 압력 액체질소 제트 해석
정기영,김남수,김용모,Jung, Kiyoung,Kim, Namsu,Kim, Yongmo 한국액체미립화학회 2017 한국액체미립화학회지 Vol.22 No.3
This paper describes numerical modeling of transcritical and supercritical fluid flows within a liquid propellant rocket engine. In the present paper, turbulence is modeled by standard $k-{\varepsilon}$ model. A conserved scalar approach in conjunction with multi-environment probability density function model is used to account for the turbulent mixing of real-fluids in the transcritical and supercritical region. The two real-fluid equations of state and dense-fluid correction schemes for mixtures are used to construct thermodynamic data library based on the conserved scalar. In this study, calculations are made on two cryogenic nitrogen jets under different chamber pressures. Sensitivity analysis for two different real-fluid equations of sate is particularly emphasized. Based on numerical results, precise structures of cryogenic nitrogen jets are discussed in detail. Numerical results show that the current real-fluid model can predict the essential features of the cryogenic liquid nitrogen jets.
정기영(K.Y. Jung),안국빈(G.B. Ahn),정성기(S.K. Jung),명노신(R.S. Myong),조태환(T.H. Cho),신훈범(H.B. Shin),정주현(J.H. Jung),최영호(Y.H. Choi),김정훈(J.H. Kim) 한국전산유체공학회 2011 한국전산유체공학회 학술대회논문집 Vol.2011 No.5
Ice accretion on aircraft surface can greatly deteriorate the safety of aircraft. In particular, it can be a cause of impediment for aircraft performances such as aerodynamic characteristics, control, and engine. Numerical simulation of icing accretion based on the state-of-art CFD techniques can be alternative to expensive icing wind tunnel test or flight test. In this study, icing conditions are defined in order to predict the ice accretions around the air intake of aircraft. Then the range and amount of ice accretion on the intake in icing wind tunnel were investigated. In addition, a study on the size effect of icing wind tunnel was conducted in order to check the compatibility with the real in-flight test environment.
정기영(Ki-Young Jung),곽동주(Dong-Joo Kwak),성열문(Youl-Moon Sung) 대한전기학회 2010 대한전기학회 학술대회 논문집 Vol.2010 No.7
In this study, used simplest sandwich cells containing Ru2? liquid electrolytes in order to clarify the role of nanoporous ITO electrodes. And, the cell structure is as follow: F:SnO₂ glass/nanoporous ITO/ tris(2,2'-bipyridy)ruthenium(Ⅱ) colplex [Ru(bpy)₃(PF?)₂] in propylene carbonate/ F:SnO₂ glass. Nanoporous indium tin oxide (ITO) powder was synthesized employing a new route sol-gel combustion hybrid method using Ketjen Black as a fuel. The nano porous ITO powder was composed of SnCl4-98.0% (aqueous solution) and In (NO₃)₃ · 5H₂O-99.999% (aqueous solution), produce with a NH₄OH (aqueous solution) with sol-gel method as a catalyst. The result, we found that ECL intensities increased rapidly by use of cathodes with nanoporous ITO layers. And, porous ITO electrodes were confirmed to be efficient for ECL devices as well as solar cell devices. It is thought that the increases in the ECL intensities may be associated with both formation of Ru? in porous ITO electrodes and the process taking place after reduction of Ru? which occurs in the nanoporous electrodes.
정기영(K.Y. Jung),안국빈(G.B. Ahn),명노신(R.S. Myong),조태환(T.H. Cho),정성기(S.K. Jung),신훈범(H.B. Shin) 한국전산유체공학회 2012 한국전산유체공학회지 Vol.17 No.2
Ice accretion on the surface of aircraft in flight can adversely affect the safety of aircraft. In particular, it can cause degradation of critical aircraft performances such as maximum lift coefficient and total pressure recovery factor in engine air intake. In this study, computational prediction of ice accretion around a rotorcraft air intake is conducted in order to identify the impingement region with high droplet collection efficiency. Then the amount of ice accretion on the air intake, which is essential in determining the required power of ice protection system, is calculated. Finally, the effect of icing wind tunnel size is investigated in order to check the compatibility with the real in-flight test environment.
나노조작기 및 집속이온빔을 이용한 정밀 나노튜브 탐침의 제작
정기영(Jung Ki Young),박병천(Park Byong Chon),안상정(Ahn Sang Jung),최진호(Choi Jinho) 대한기계학회 2005 대한기계학회 춘추학술대회 Vol.2005 No.11
Precision carbon nanotube tip for atomic force microscope was fabricated where carbon nanotube orientation is controlled within the precision of 1 degree. The orientation, diameter and length of carbon nanotube tip are crucial factors for faithful profiling of surface patterns. With a nano-manipulation while viewing scanning electron microscope live image followed by focused ion beam process, precision carbon nanotube tip could be made. Precision carbon nanotube tip acts as a normal nanotube tip without Focused ion beam process. Further it maintains the elasticity. Precision tip can, in principle, enter the trench or hole less than 70 ㎚, which is impossible with the current state of the art silicon tip for critical dimension atomic force microscope.
CCD 카메라가 장착된 광학현미경을 사용한 폴리스티렌구 (3 ㎛와 10 ㎛)의 평균지름측정
정기영(Ki Young Jung),박병천(Byong Chon Park),강주식(Ju Sik Kang),송원영(Won Young Song),오범환(Beom-hoan O) 한국광학회 1998 한국광학회지 Vol.9 No.6
중심거리측정법은 서로 붙어있는 두 입자 중심점간의 거리를 측정하여 입자의 지름을 구하는 방법이다. 표면장력에 의해 배열이 형성된 시편 입자들의 초점군을 투과식 광학현미경에 평행 레이저광을 입사시켜 얻어내고 CCD 카메라로 영상을 받아 전산 분석하였다. Global lab image라는 영상처리 프로그램으로 초점들의 중심점을 찾고 붙어있는 입자들의 중심점간 거리를 화소(CCD 카메라의 pixel) 단위로 계산하였으며, 화소의 좌표는 레이저 간섭계로 변위를 읽는 이송대를 이용하여 교정하였다. 기존의 측정방법을 개선하여 빠른 시간에 간편하게 측정하면서도 표준입자의 배율교정에 충분한 불확도를 얻을 수 있었다. 본 실험에는 NIST 인증물질인 3 ㎛와 10 ㎛ 폴리스티렌구(NIST SRM 1962, 1960)를 측정하였으며, 1%이하의 불확도(신뢰도 99% 수준)로써 NIST 결과와 비교하였다. Center Distance Finding (CDF) is a technique to find the sphere diameter by measuring the distance between two contacting spheres. The focal spots of the sphere clusters are formed in the back-focal plane by the transmission-mode optical microscope with the pseudothermal illumination source. Digital images taken by the CCD camera were processed by the software called Global Lab Image. The centers of the focal spots are found and the spot positions are expressed in terms of the CCD pixel elements, whose coordinates are calibrated by a heterodyne interferometer. The new CDF measurement system has been developed, which are more advantageous in time and convenience than the existing system, while the measurement uncertainty remains sufficient for its use as a magnification standard for optical microscopy. Two kinds of polystyrene spheres whose nominal diameters 3 and 10 ㎛ (NIST SRM 1962 and 1960) are measured with the uncertainty less than 1% at the confidence level of 99%, and the results are compared with the results of National Institute of Standards and Technology.
비정렬 격자 기반의 결빙 액적 해석을 위한 유한체적 기법
정기영(K. Y. Jung),정성기(S. K. Jung),명노신(R. S. Myong) 한국전산유체공학회 2013 한국전산유체공학회지 Vol.18 No.2
Ice accretion on the solid surface is an importance factor in assessing the performance of aircraft and wind turbine blade. Changes in the external shape due to ice accretion can greatly deteriorate the aerodynamic performance. In this study, a three-dimensional upwind-type second-order positivity-preserving finite volume CFD scheme based on the unstructured mesh topology is developed to simulate two-phase flow in atmospheric icing condition. The code is then validated by comparing with NASA IRT experimental data on the sphere. The present results of the collection efficiency are found to be in close agreement with experimental data and show improvement near the stagnation region.
정기영(Ki-Young Jung),박선희(Sun-Hee Park),곽동주(Dong-Joo Kwak),성열문(Youl-Moon Sung) 한국조명·전기설비학회 2010 한국조명·전기설비학회 학술대회논문집 Vol.2010 No.9월
In this study, used simplest sandwich cells containing Ru2? liquid electrolytes in order to clarify the role of nanoporous ITO electrodes. And, the cell structure is as follow: F:SnO₂ glass/ nanoporous ITO/ tris(2,2'-bipyridy)ruthenium(Ⅱ) colplex [Ru(bpy)₃(PF?)₂] in propylene carbonate! F:SnO₂ glass. Nanoporous indium tin oxide (ITO) powder was synthesized employing a new route sol-gel combustion hybrid method using Ketjen Black as a fuel. The nano porous ITO powder was composed of SnCl₄~98.0% (aqueous solution) and In (NO₃)₃ · 5H₂O-99.999% (aqueous solution), produce with a NH₄OH (aqueous solution) with sol-gel method as a catalyst. The result, we found that ECL intensities increased rapidly by use of cathodes with nanoporous ITO layers. And, porous ITO electrodes were confirmed to be efficient for ECL devices as well as solar cell devices. It is thought that the increases in the ECL intensities may be associated with both formation of Ru? in porous ITO electrodes and the process taking place after reduction of Ru? which occurs in the nanoporous electrodes.
Al6061S 합금의 고속엔드밀 절삭시 치수오차와 표면정도 추이에 관한 연구
정기영(Ki-Young Jung) 산업기술교육훈련학회 2011 산업기술연구논문지 (JITR) Vol.16 No.4
High speed machining aims to raise the productivity and efficiency by making more precise and higher value-added products than other machining method by means of the high speediness of spindle and feed drive system. The purpose of this study is to investigate the effects of the run-out of endmill on the dimension precision of workpiece and to obtain the fundamental data on high speed machining, which is available by machining the side of Al-alloy with solid carbide endmills in high speed machining center and by measuring dimensions and surface roughness. From the results of experimentations followings are obtains; if spindle speed is ultrahigh in conditions that radial depth of cut and feed per tooth are very small, highly precise and accurate products are to be made efficiently with feed rate and so we can raise productivity.