충격하중(衝擊荷重)을 받는 구조물(構造物)의 소성(塑性)모델에 따른 거동분석(擧動分析)

안병기,이상호,Ahn, Byoung Ki,Lee, Sang Ho 대한토목학회 1992 대한토목학회논문집 Vol.12 No.2

충격하중을 받는 구조물은 초고압에서 부터 저압까지 다양한 압력을 짧은 시간에 경험하게 된다. 따라서 이들 구조물을 해석하기 위해서는 실제 물체의 재료특성을 표현할 수 있는 구성 법칙(constitutive law)이 필요하게 된다. 본 연구에서는 압력 부종속모델(pressure independent model)인 Von-Mises 모델과 압력 종속모델(pressure dependent model)인 Drucker-Prager 모델을 사용하여 충격과 폭발 현상시 발생하는 응력파의 전파과정(propagation process)을 재료특성에 따라 비교 분석하였다. 응력파의 전파과정을 연구하기 위한 지배 방정식(governing equation)으로서는 물체에 종속되어 있는 라그란지안 좌표계(lagrangian coordinate system)로 표현된 운동량과 질량보존(conservation of momentum and mass)법칙을 사용하였으며 또한 충격전면(shock front)에 연속성을 부여하기 위해 인공점성(artificial viscosity)을 운동량 보존식에 첨가하였다. 주요 방정식을 풀기 위한 수치해석법으로는 시간과 공간 좌표계로 구성된 유한차분법(finite difference method)을 사용하였으며 소성변형률을 구하기 위한 소성이론으로서는 Associated normality flow rule을 사용하였다. Under the intense-impulsive loading, structures are subjected to the wide range of pressures at an instantaneous time. The constitutive laws capable to describe the material behavior under the extreme pressure as well as the low pressure are necessary for the analysis of the structural behavior under the intense -impulsive loadings. In this study, two plastic models, the pressure independent Von-Mises model and the pressure dependent Drucker-Prager model, are employed for the wave propagation analysis. Governing equations of this study are conservation equations of momentum and mass in Lagrangian coordinate system which is fixed to the material. Due to the shock-front which violates the continuity assumptions inherent in the differential equations numerical artificial viscosity is used to spread the shock front over several computational zones. These equations are solved by Finite Difference Method with discretized time and space coordinates. The associate normality flow rule as a plastic theory is implemented to find the plastic strains.

장기(長期) 유출(流出) 해석(解析)에서의 감수곡선(減水曲線) 계수(係數) 변화(變化)

안병기 ( Ahn Byoung Gi ),김태철 ( Kim Tai Cheol ),박승기 ( Park Seong Ki ),이경구 ( Lee Kyung Goo ) 한국농공학회 1991 韓國農工學會誌 : 전원과 자원 Vol.33 No.1

Recession constants are generally obtained from the hydrographs using the master recession curves method, and applied to estimate the daily streamflow and the variation of river water level in dry period. But, it is very complicated and tedious work to estimate the recession constans from the stations with no or scarce streamflow data. The 1,470 recession events were taken from the hydrographs at 31 hydrologic stations in Korea and analyzed to get the generalized recesson constants. The characteristics of watershed boundaries on recession constants were not significant, but the trend of monthly variations of recession constants was distinctly recognized, and the range of variations was rather wide. In this study, the formulae are suggested to estimate the average monthly interflow and baseflow recession constants from the size of watershed which are essential parameters to develop the daily streamflow model.

이차원(二次元) 파전파(波傳波) 이론(理論)에 의한 충돌현상(衝突現狀) 해석(解析)

이상호,안병기,Lee, Sang Ho,Ahn, Byoung Ki 대한토목학회 1994 대한토목학회논문집 Vol.14 No.2

충돌현상을 재현할 수 있는 이차원 파전파 컴퓨터 프로그램을 개발하였다. 불연속인 충격전면에 연속성을 부여하기 위한 기법으로 Von Neumann과 Ritchmyer가 제안한 인공점성을 수치해석시 도입하였다. 본 연구에서는 충돌물체의 재료모델로서 Von-Mises 항복함수를 이용한 탄소성 모델을 사용하였다. 개발된 컴퓨터 프로그램을 검증하기 위하여 충격을 가하는 물체와 받는 물체로 구성된 충돌현상을 재현하였다. 본 연구에서 개발된 컴퓨터 프로그램은 이차원 평면요소를 사용하였기 때문에 재현된 충돌해석 결과를 3차원에서 발생하는 실제값과 정량적으로 비교할 수는 없었으나 충돌실험시 실제로 발생하는 파괴현상을 정성적으로 분석할 수 있었다. A two-dimensional Lagrangian finite-difference computer program is developed for the wave propagation analysis of impact phenomena. The numerical scheme is the standard method originally proposed by Von Neuman and Richtmyer, using artificial viscosity to smooth shock fronts. The material model used in the study is the standard hydrodynamic-elastic-plastic relations with Von-Mises yield criterion. A test configuration consisted of a target and a projectile were calculated to understand the response of a colliding event. However, the computer code is in plane strain, the calculations were intended for generating the qualitative features of the model behaviors. Nevertheless, the computational results were consistent with the experimental observations and provided a rational basis to interpret the modes of failures.

적층계(積層係)를 통과하는 소성응력파(塑性應力波)의 전파(傳波)

이상호,안병기,강영구,Lee, Sang Ho,Ahn, Byoung Ki,Kang, Young Goo 대한토목학회 1993 대한토목학회논문집 Vol.13 No.2

충돌이나 폭파시 발생하는 기계적 에너지나 화학적 에너지는 응력파의 형태로 매체를 통과하게 되며, 매체의 자유면과 절리면을 따라 반사와 굴절을 거듭하는 매우 복잡한 과정을 거치게 된다. 본 연구에서는 재료특성을 달리하는 층을 통과하는 소성응력파의 전파과정을 압력 부종속 모델인 Von-Mises 모델을 사용하여 연구하였다. 응력파의 전파과정을 연구하기 위한 지배 방정식(governing equation)으로서는 물체에 종속되어 있는 라그란지안 좌표계(lagrangian coordinate system)로 표현된 운동량과 질량보존(conservation of momentum and mass)법칙식을 사용하였으며 또한 충격전면(shock front)에 연속성을 부여하기 위해 인공점성(artificial viscosity)을 운동량 보존식에 첨가하였다. 주요 방정식을 풀기 위한 수치해석법으로는 시간과 공간 좌표계로 구성된 유한차분법(finite difference method)을 사용하였으며 소성변형률을 구하기 위한 소성이론으로서는 associated normality flow rule을 사용하였다. The stress waves generated by the mechanical energies by impact or the chemical energies by the explosions are transmitted through medium. The wave propagation process through medium is a very complicated procedure due to the reflections and refractions of the waves at the free surfaces and interfaces. In this study the pressure independent Von-Mises model is employed for the wave propagation analysis in the layered systems. Governing equations of this study are conservation equations of momentum and mass in Lagrangian coordinate system which is fixed to the material. Due to the shock-front which violates the continuity assumptions inherent in the differential equations numerical artificial viscosity is used to spread the shock front over several computational zones. These equations are solved by Finite Difference Method with discretized time and space coordinates. The associate normality flow rule as a plastic theory is implemented to find the plastic strains.

육용 브로일러, 산란종 병아리 및 백세미육으로 제조한 춘천 닭갈비의 품질 비교

이성기(Sung Ki Lee),김희주(Hee Ju Kim),강선문(Sun Moon Kang),최원희(Won Hee Choi),무흘리신(Muhlisin),안병기(Byoung Ki Ahn),김천제(Cheon-Jei Kim),강창원(Chang Won Kang) 韓國家禽學會 2011 韓國家禽學會誌 Vol.38 No.2

본 연구는 닭 품종(18일령 브로일러, 49일령 산란종 병아리, 35일령 백세미)별 원료육으로 제조한 춘천 닭갈비의 품질을 비교하고자 실시하였다. 품종간 향기 패턴의 차이는 없었지만, 백세미육 닭갈비가 색깔이 진하고 붉었으며, 저장기간 중에 지방산화 안전성이 높고, 관능검사에 의한 기호성이 높았다. 그러므로 세 품종 중에서 백세미육으로 제조한 춘천 닭갈비의 품질이 가장 우수하였다. This study was conducted to compare the quality of Chuncheon Dakgalbi made with meat from three chicken breeds. Ross male broilers, Hy-Line Brown male chicks and White Mini male broilers were raised for 18 d, 49 d and 35 d, respectively, and slaughtered. The thigh meat from carcasses on each breed were used for this experimented. The fat content was higher in White Mini broiler meat than Ross broiler and HY-LINE BROWn chick meat (P<0.05). No differences were observed in aroma patterns of raw meat and Chuncheon Dakgalbi between all breeds. The Chuncheon Dakgalbi made with White mini broiler meat had higher color stability and lipid oxidation stability and showed higher sensory scores such as visual color and overall acceptability. Therefore, the Chuncheon Dakgalbi made with White Mini broiler meat showed the best quality among the three chicken breeds.

韓國 河川의 日 流出量 模型

김태철,박승기,안병기,Kim, Tae-Cheol,Park, Seong-Ki,Ahn, Byoung-Gi 한국수자원학회 1996 물과 미래(한국수자원학회지) Vol.29 No.5

우리나라의 강수와 유역특성을 고려하여 일강우량과 증발량의 입력자료로 일유출량을 모의발생할 수 있는 "한국 하천의 일 유출량 모형(DAWAST)"을 개발하였다. 이 모형은 개념화 모형을 기본모형으로 최적화모형, 일반화모형 및 수계화모형 등 3개의 부모형으로 구성되어 있다. 기본모형은 유역을 지표면, 불포화층과 포화층의 3개 저수층으로 단순화하고 각 저수층에서 일단위로 물수지를 분석하였다. 최적화모형은 관측유출자료가 있는 유역에서 최적화기법으로 매개변수를 보정하여 적용하고, 일반화모형은 유역특성인자로부터 매개변수를 예측하여 미계측 중, 소유역에 적용하고, 수계화모형은 유역특성인자 조사가 없거나 어려운 지점에서 최적화기법으로 분석된 수문지점의 매개변수를 전용하여 미계측 대유역에 적용하여 일유출량을 추정한다.유출량을 추정한다. Daily streamflow model, DAWAST, considering the meteorologic and geographic characteristics of the Korean watersheds has been developed to simulate the daily streamflow with the input data of daily rainfall and pan evaporation. The model is the conceptual one with three sub-models which are optimization, generalization, and regionalization models. The conceptual model consists of three linear reservoirs representing the surface, unsaturated, and saturated soil zones and water balance analysis was carried out in each soil zones on a daily basis. Optimization model calibrates the parameters by optimization technique and is applicable to the watersheds where the daily streamflow data are available Generalization model predicts the parameters by regression equations considering the geographic, soil type, land use, and hydrogeologic characteristics of watershed and is appicable to ungaged medium or small watersheds. Regionalization model cites the parameters from the analysed ones considering river system, latitude and longitude, and is applicable to ungaged large watersheds.

육계 사료 내 마늘분말의 첨가급여가 육계 성장과 HMG-CoA Reductase의 mRNA 발현에 미치는 영향

유선종 ( Sun Jong You ),안병기 ( Byoung Ki Ahn ),강창원 ( Chang Won Kang ) 한국동물자원과학회 2009 한국축산학회지 Vol.51 No.4

장기유출(長期流出) 해석(解析)을 위한 유효우량(有效雨量) 추정(推定)

김태철 ( Kim Tai Cheol ),안병기 ( Ahn Byoung Ki ),박승기 ( Park Seung Ki ) 한국농공학회 1989 韓國農工學會誌 : 전원과 자원 Vol.31 No.2

Based on the theory of runoff equation proposed by SCS, the actual storage capacity(Sa) as a modified retention paramater was introduced to estimate the effective rainfall for the daily streamflow analysis. During a storm, the actual storage capacity is limited by either soil water storage or infiltration rate as precipitation increases. Therefore, it was assumed that Sa is dependent on the baseflow before storm runoff(Qb) corresponding to soil water storage and the total amount of precipitation(P) corresponding to infiltration rate of a watershed. Effective rainfalls (Direct run-offs) estimate4 from SCS equation using Sa were compared with observed effective rainfalls at 10 watersheds in Geum river watershed boundary. 1. Regression equation for Sa was supposed S_a=C_o+C₁ × P+C₂ × Qb Regression coefficients were highly significant at the level of 0. 01 and R² were 0.57 to 0.73. 2. The adjustment of coefficient of initial abstraction was made according to the storm size. It was adjusted to 0.25 for 30mm or less, 0.23 for 30 to 80mm, 0.20 for 80 to 200mm, and 0.1 for 200mm or more. 3. Regression equations between estimated and observed effective rainfall showed that slopes were 0.857 to 1.029 and R² were 0.779 to 0.989,

현장투수계를 이용한 유역의 평균침투계수 산정

박승기 ( Park Seung Ki ),김태철 ( Kim Tai Cheol ),안병기 ( Ahn Byoung Gi ) 한국농공학회 1999 한국농공학회 학술대회초록집 Vol.1999 No.-

Three of the most important factors governing liquid transmission in unsaturated soils are field-saturated hydraulic conductivity, K_fs, matric flux potential, Ø_m, and sorptivity, S. The Guelph Permeameter is an in-hole constant-head permeameter, employing the Mariotte Principle. The study was carried out to investigate the characteristics of the watershed average infiltration coefficient measured by the Guelph Permeameter at the Backokpo watershed in the Han river and at the Bangdong watershed in the Keum river.

칼슘의 수준별 급여 및 25-hydroxycholecalciferol의 사료 내 첨가가 종란 생산성 및 후기 난각질에 미치는 영향

김은집 ( Eun Jib Kim ),안병기 ( Byoung Ki Ahn ),강창원 ( Chang Won Kang ) 한국동물자원과학회 2009 한국축산학회지 Vol.51 No.4