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선형 격자 형성 방정식을 이용한 직교 격자 형성에 관한 연구
이상욱(S. W. Lee),권장혁(J. H. Kwon),권오준(O. J. Kwon) 한국전산유체공학회 2000 한국전산유체공학회 학술대회논문집 Vol.2000 No.5
A method of two and three dimensional orthogonal grid generation with control of spacing by using the covariant Laplace equation is presented. An important feature of the methodology is it's ability to control effectively the grid spacing especially near the boundaries still maintaining good orthogonality in whole field.<br/> The method is based on the concept of decomposition of global transformation into consecutive transformation of an approximate conformal mapping and an auxiliary arthogonal mapping to have linear and uncoupled equation. Control of cell spacing is based on the concept of reference are length, and orthogonal correction is performed in the auxiliary domain.<br/> It is concluded that the methodology can successfully generate well controlled orthogonal grids around bodies of 2 and 3 dimensional configurations.
유한요소해석을 이용한 더스트 씰 밀봉성에 대한 설계변수의 영향평가
이광오(K. O. Lee),이상욱(S. U. Lee),허영민(Y. M. Huh),강성수(S. S. Kang) 한국정밀공학회 2006 한국정밀공학회 학술발표대회 논문집 Vol.2006 No.5월
Usually, hydraulic cylinder is widely used as the actuator in the equipment of construction machines, airplane and military machines. In case of these devices, due to use under severe environment such as water, SiO² and dust, etc. seal which has high packing ability and long service life has been required. These characteristics are largely influenced by material and geometries of seal such as approach angle, withdrawal angle and interference. Recently, many a study about seal material has been performed so that many materials have been developed. But the concrete studies including the relationships between geometry of seal and sealing performance have hardly been performed yet. Therefore, in this study, we predicted the deformation behavior and contact normal distribution of dust seal with the variation of geometries of seal lip using finite element analysis. And based on the results of analyses, we discussed the effects of the design variables for sealing performance of the dust seal.
선형 격자 형성 방정식을 이용한 직교 격자 형성에 관한 연구
이상욱(S. W. Lee),권장혁(J. H. Kwon),권오준(O. J. Kwon) 한국전산유체공학회 2000 한국전산유체공학회지 Vol.5 No.1
A method of two and three dimensional orthogonal grid generation with control of spacing by using the covariant Laplace equation is presented. An important feature of the methodology is its ability to control effectively the grid spacing especially near the boundaries still maintaining good orthogonality in whole field.<br/> The method is based on the concept of decomposition of the global transformation into consecutive transformation of an approximate conformal mapping and an auxiliary orthogonal mapping to have linear and uncoupled equations. Control of cell spacing is based on the concept of reference arc length, and orthogonal correction is performed in the auxiliary domain.<br/> It is concluded that the methodology can successfully generate well controlled orthogonal grids around bodies of 2 and 3 dimensional configurations.
비정렬 격자계에서 연속 Adjoint 방법을 이용한 헬리콥터 로터 블레이드의 제자리 비행 공력 형상 최적설계
이상욱(S. W. Lee),권오준(O. J. Kwon) 한국항공우주학회 2005 韓國航空宇宙學會誌 Vol.33 No.1
비정렬 격자계에서 continuous adjoint 방정식을 사용하여 제자리 비행을 하는 헬리롭터 로터 블레이드에 대한 공력 형상 최적설계 기법을 개발하였다. 효율적인 민감도 계산 을 위해 회전좌표계에서 continuous adjoint 민감도 해석 기법을 유도하였다. 설계과정의 반복적인 수치계산의 효율을 높이기 위해서 영역 분할 기법에 기반을 둔 병렬처리 기법 을 도입하였다. 끝단 와류의 정확한 포착을 위해서 끝단와류를 따른 격자적응을 수행하였다. 이러한 방법은 Caradonna와 Tung의 실험형상 및 UH60 헬리콥터 로터 블레이드의 공력 최적설계에 적용되었으며, 본 연구에서 사용된 최적설계 기법을 이용하면 일정한 추력을 유지하면서 요구동력을 현저하게 줄일 수 있음을 보였다. An aerodynamic shape optimization technique has been developed for helicopter rotor blades in hover based on a continuous adjoint method on unstructured meshes. The Euler flow solver and the continuous adjoint sensitivity analysis were formulated on the rotating frame of reference for hovering rotor blades. In order to handle the repeated evaluation of the design cycle efficiently, the flow and adjoint solvers were parallelized using a domain decomposition strategy. A solution-adaptive mesh refinement technique was adopted for the accurate capturing of the tip vortex. Applications were made for the aerodynamic shape optimization of Caradonna-Tung rotor blades and UH60 rotor blades in hover. The results showed that the present method is an effective tool to determine optimum aerodynamic shapes of rotor blades requiring less torque while maintaining the desired thrust level.
주인원,신천식,김재현,이점훈,손승호,이상욱,Joo, I.O.,Sin, C.S.,Kim, J.H.,Lee, J.H.,Son, S.H,Lee, S.U. 한국전자통신연구원 2011 전자통신동향분석 Vol.26 No.4
미국에서 군용목적으로 개발된 GPS는 21세기에 접어들면서 차량용 내비게이션, 스마트폰 등의 일상생활에서 쉽게 사용될 뿐만 아니라, 이동통신망, 전력망, 금융망 등 국가 기간통신망에서도 활용되고 있으며, 날이 갈수록 다양한 분야에서 매우 중요한 역할을 담당하고 있다. 하지만, GPS는 신호세기가 미약하므로 전파 방해에 취약하여 전파교란되기 매우 쉽다. 최근 서해안 및 금강산 지역의 GPS 교란 신호 발생으로 인해 이통사 및 항공사 등에서 GPS 신호를 활용하는데 심각한 문제를 야기하였다. 본 고에서는 GPS 전파교란 문제를 예방 및 피해를 최소화하기 위하여 국외에서 개발중인 GPS 전파교란 감시 기술 동향을 살펴보고, 국내에서 위성항법지상국 기술개발을 통하여 확보된 위성항법 신호감시국 기술과 추진 중인 전파교란 감시 기술개발 현황에 대하여 소개한다.
HBeAg양성인 만성 B형 간염 환자에서 alpha-interferon치료후 반응형태와 장기적 결과, 그리고 lamivudine의 가치
김현영 ( H. Y. Kim ),김성훈 ( S. H. Kim ),윤병철 ( B. C. Yoon ),이상욱 ( S. O. Lee ),한병훈 ( B. H. Han ) 대한소화기학회 2002 대한소화기학회 춘계학술대회 Vol.2002 No.-
<목적> HBeAg 양성 만성 B형 간염환자에서 alpha-interferon과 lamivudine의 효과 판정기준과 장기적 효과에 대한 연구는 아직까지도 제한적이다. 이에 연자들은 HBeAg 양성인 만성 B형 간염 환자들에서 alpha-interferon의 장기적 효과와 효과판정 기준, 그리고 치료 실패 군에서 lamivudine의 가치를 확인하기 위해서 다음과 같은 연구를 시행하였다. <방법> HBeAg양성 만성B형간염으로 진단받고 alpha-int
국내시장에 유통중인 한우 및 수입 쇠고기 냉동 등심 부위의 물리 화학적 미생물학적 및 관능적 품질 특성
이무하,민중석,김일석,변준석,강석남,이상욱 한국축산학회 2000 한국축산학회지 Vol.42 No.1
This study was carried out to compare qualities of the frozen imported beef loins with those of the Han-woo beef loins. Samples were stored at -20℃. In the proximate analysis of composition of beef loins, there were significant differences in crude fat, crude protein and moisture(P$lt;0.001). Han-woo loins were higher in crude protein and moisture than those of the other loins. In the analysis of microorganisms, TPC(Total Plate Counts) and psychrotroph bacterial counts of the Han-woo loins showed the lowest value. TBARS(Thiobarbituric Acid Reactive Substance) values were less than 0.4㎎MA/㎏ in all samples, VBN(Volatile Basic Nitrogen) values were less than 20㎎/100g in all samples. In the descriptive analysis with scaling for raw and cooked beef loins, it was observed that off-flavor of American raw beef loins was higher than that of other ones. In cooked beef loins, acceptability was higher in the Han-woo loins than in the imported ones.
한우 및 수입산 쇠고기 냉장 묵심 부위의 물리 화학적 미생물학적 및 관능적 특성
이무하,김일석,김진형,김용곤,이상욱,이종문 한국축산학회 2000 한국축산학회지 Vol.42 No.1
This study was carried out to compare qualities of Han-woo chuck rolls with those of the imported beef chuck rolls(American, Australian). The beef chuck rolls were aerobically packed by polyethylene films and were stored at 2℃. Han-woo check rolls were higher in crude fat than other ones but were lower in moisture than other ones. The three treatments were significantly different in crude fat(P$lt;0.001), crude protein(P$lt;0.01) and moisture(P$lt;0.001). Both total plate count and psychrotrophs appeared the highest in Australian beef chuck rolls and the lowest in Han-woo chuck rolls. VBN values of American beef chuck rolls were higher than those of other ones. Han-woo chuck rolls showed the highest value in water holding capacity(P$lt;0.05), but the lowest value in shear force(P$lt;0.001). Lightness(L*value) and yellowness(b*value) were higher in American beef chuck rolls than in other ones. In the descriptive analysis with scaling for cooked beef loin, Australian beef chuck rolls were evaluated as being better in total acceptability.