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횡단류 내 평판 위에 놓인 원형 실린더 주위의 유동장 및 열전달에 관한 연구
이기백,손정호,양장식,Lee, Gi-Baek,Son, Jeong-Ho,Yang, Jang-Sik 대한기계학회 1996 大韓機械學會論文集B Vol.20 No.4
The present study is concerned with the heat transfer enhancement associated with a symmetrical or asymmetrical horseshoe vortex in front of and around the circular cylinder centered between the side walls of a wind tunnel. The static pressure measurements and the flow visualization in front of and around cylinders have been performed to determine the existence of horseshoe vortex. The hue-capturing method using the thermochromatic liquid crystals with great spatial resolution was used to obtain the local information of the endwall heat transfer coefficients. In case of one cylinder, the convective heat transfer coefficients of the region where the horseshoe vortex exists are larger than those of any other region. In case of two cylinders with tandem arrangement, the heat transfer rate of gap spacing (d/D= 1.5) is higher than that of gap spacings (d/D=2.0 or 2.5).
색상 포착 기법과 수치계산을 이용한 3차원 밀폐 공간내의 자연대류 연구
이기백,김태영,양장식,Lee, Gi-Baek,Kim, Tae-Yeong,Yang, Jang-Sik 대한기계학회 1997 大韓機械學會論文集B Vol.21 No.12
The natural convection of a horizontal layer heated from below in a three-dimensional rectangular enclosure was dealt with both numerically and experimentally. The aspect ratios are 1:2:3.5 and Boussinesq fluid is water with the Prandtl number of 5.0. This experimental study showed how to measure the variation of temperature field in a 3-D rectangular enclosure with small aspect ratios by using TLC(Thermochromic Liquid Crystal) and color capturing technique. The experimental temperature field had periodic characteristics of 75 sec at Ra=2.37*10$^{5}$ . But the numerical convection flow had periodic characteristics of 79 sec at the same Rayleigh number. In three dimensional computation it was found that the convection roll structure bifurcated from four rolls to two rolls as the Rayleigh number is increased.
공정시스템 , 이동현상 , 화학공정안전 : 응집과 파괴현상을 고려한 결정화공정의 동적모사법 연구
이기백(Gi Baek Lee),윤인섭(En Sup Yoon) 한국화학공학회 2002 Korean Chemical Engineering Research(HWAHAK KONGHA Vol.40 No.2
This study focuses on the simulation method for crystallization processes, that is the most important unit operations and is widely used in the chemical industry such as pigments, pharmaceuticals, and detergents, etc. The process includes the kinetics of nucleation, growth, agglomeration, and breakage. Because the models are very complex to become partial and ordinary differential, algebraic and integral equations(IPDAE), it is very difficult to get a numerical solution. And, it makes process design and analysis depend on experiments. In this study, the simulation is based on the method of characteristics to avoid the difficulties of numerical diffusion and stability that bother the previous methods in this area. In order to improve the accuracy and efficiency of the simulation, this study combines the method of characteristics with the adaptive mesh method, which adaptively adds and eliminates meshes as the solution varies. The proposed method can conserve crystal number and mass in the representation of agglomeration/breakage event and mesh adaptation. The proposed method is validated through the simulation of case studies.
<특집>소크라테스 이전의 철학 : 필롤라오스의 세 가지 근본 원리와 수
이기백 ( Gi Baek Lee ) 한국철학사상연구회 2002 시대와 철학 Vol.13 No.2
In this paper I consider (1) why Philolaus explained the cosmos by three principles: `limiters`, `unlimiteds` and `harmony`, (2) what is meant by `limiters`, `unlimiteds` and `harmony`, and (3) which relation do `limiters` and `unlimiteds` have with `numbers`. The purpose of this paper is to show the following: (1) Philolaus synthesized critically two kind of earlier Presocratic thoughts by accepting both `unlimiteds` and `limiters` as principles, (2) material elements as fire, air, etc are `unlimiteds`, on the other hand geometrical or arithmetical elements are `limiters`, and (3) Aristotle`s testimonies that all things are numbers, and that the odd is limited and the even is unlimited, didn`t reflect correctly 5th-Century Pythagoreanism.
이선웅 ( Sunwung Lee ),서영원 ( Yeong-won Seo ),서유진 ( Yu-jin Suh ),이기백 ( Gi-baek Lee ),이영섭 ( Young-sup Lee ) 한국정보처리학회 2017 한국정보처리학회 학술대회논문집 Vol.24 No.2
본 논문에서는 다중의 저가형 단일포인트 라이다와 모터를 결합하여, 고가형 3D 라이다와 유사한 스캐닝 결과를 얻을 수 있는 방법을 고안하였다. 즉, 본 연구에서는 하나의 라이다로 2D 평면을 스캐닝 했을 때의 한계를 보완하는 방법을 제시하고자, 단일포인트 라이다 3 개를 사용하여 3D 공간을 스캐닝 하는 시스템을 구현하였다.