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가스터빈엔진용 축류압축기의 공력 설계 기법개발 및 적용
鄭喜澤 慶尙大學校生産技術硏究所 1996 生産技術硏究所論文集 Vol.12 No.-
The aerodynamic design system of the axial-flow compressors for the large-scaled industrial gas turbines was developed using the conventional methods. The current design procedure is composed of the four separate program modules; i.e., 1) preliminary design 2) computation of the aero-thermal properties using the streamline curvature method, 3) determination of the blade profiles and 4) the estimation of the full-stage compressors at the off-design conditions. Using this design systems, the aerodynamic design was performed for the six-stage LP compressor for 100 MW class industrial engines. The aero-thermal conditions for the full-stage and full-span blade design was computed and the detail design of the first rotor blade was performed. The LPC engine performance at the variable speedline and flow rates are predicted using the simple meanline stage-stacking methods. In addition, the conceptual design of the LPC components including the inlet flow passage and the exit turning vane to the intercooler was done for the mechanical design as the future work.
가스터빈엔진 내부유동장 해석용 계산격자점 생성기법 연구
鄭喜澤 慶尙大學校生産技術硏究所 1997 生産技術硏究所論文集 Vol.13 No.-
Computaional grids used in the solution of the Naveir-Stokes equations for numerical simulation of gas-turbine flow fields are generated such that they are suited both for the geometry complexities and for the flow characteristics. The present grid generation system adopts the multiblock structure based on the structured H-grids. The numerical algorithm adopts the combination of the algebraic and elliptic method to create the internal grids efficiently and quickly. The system consists of four separate modules for blade-geometry modeling and grid generation. The grid generation method generates a series of two-dimensional grids in the blade-to-blade passage to build up the three-dimensional grid. The system input is made of the results of the preliminary design, i.e., flow-path, aerodynamic conditions along the spanwise direction, and the blade profile data. The final grids generated from each module of the system are used as the preprocessor for the performance prediction of the sectional blade, the blade-stacking process and the three-dimensional flow simulation inside the gas-turbine flow passage. For purposes of illustration, the grid generation system is applied to cascade flow simulations of a transonic turbine rotor and aerodynamic design of the LP compressor.
서영수,정희택,권진회 경상대학교 생산기술연구소 2003 工學硏究院論文集 Vol.19 No.-
The rotating machinery such as the centrifugal pump related to the safety in nuclear power plants have to evaluate their structural integrity and operability through the experimental test, computational analysis or the combination of the test and the analysis. The paper presented is currently aimed at the computational analysis of the designed nuclear pump in the sense of the structural integrity and operability for the centrifugal machinery pump. The commercial finite element analysis program(MSC/NASTRAN)was available to perform the static analysis on the horizontal centrifugal pump installed on the gas stripper system. The numerical results are analysed with respect to the natural frequency, nozzle loads as well as seismic loads, and also the shaft critical analysis along with evaluation of deflection are verified to ensure that the design results meet the seismic requirements.
익렬유동의 수치해석에서의 복합 정렬-비정렬 격자계의 적용 연구
정향남,정희택 慶尙大學校 經營行政大學院 2004 工學硏究院論文集 Vol.20 No.-
Numerical simulation has been performed to examine the effects of the computational grids on the prediction of the flow characteristics inside the transonic turbine cascades. Three kinds of computational grids are applied to the high-turning transonic turbine rotor blades and are compared in the sense of stability and accuracy. In addition, the grid adaptation has been tried in order to improve the prediction of the blade performance.
Numerical simulations of elliptic particle suspensions in sliding bi-periodic frames
Chung, Hee-Taeg,Kang, Shin-Hyun,Hwang, Wook-Ryol The Korean Society of Rheology 2005 Korea-Australia rheology journal Vol.17 No.4
We present numerical results for inertialess elliptic particle suspensions in a Newtonian fluid subject to simple shear flow, using the sliding bi-periodic frame concept of Hwang et al. (2004) such that a particulate system with a small number of particles could represent a suspension system containing a large number of particles. We report the motion and configurational change of elliptic particles in simple shear flow and discuss the inter-relationship with the bulk shear stress behaviors through several example problems of a single, two-interacting and ten particle problems in a sliding bi-periodic frame. The main objective is to check the feasibility of the direct simulation method for understanding the relationship between the microstructural evolution and the bulk material behaviors.
정희택(Hee-Taeg Chung) 한국전산유체공학회 1995 한국전산유체공학회 학술대회논문집 Vol.1995 No.-
A multiblock grid generation has been developed to be reliably used for a Navier-Stokes simulation of the turbomachinery flow-fields A multiblock structure simplifies the creation of structured H-grids about complex turbomachinery geometries and facilitate the creation of a grid in the tip flow region. The numerical algorithm adopts the combination of the algebraic and elliptic method to create the internal grids efficiently and quickly. The grid refinement process is enhanced by developing strategies to utilized Bezier curves and splines along with weighted transfinite interpolation technique and by formulating the grid-imbedding method for the viscous boundary-layer meshes. For purposes of illustration, the grid generator is applied to the high turning turbine rotor blades. Three different types of computational grids are provided to be compared with respect to the grid adaptation to the flow simulations. The grid quality of the multiblock structure is good in the passages, with gloval orthogonality and adequate smoothness.
Koo, Hee-Sang,Kang, Sung-Don,Lee, Ju-Hwan,Kim, Nam-Ho,Chung, Hun-Taeg,Pae, Hyun-Ock The Korean Neurosurgical Society 2009 Journal of Korean neurosurgical society Vol.46 No.4
Objective : Triptolide (TP) has been reported to suppress the expression of mitogen-activated protein kinase (MAPK) phosphatase-1 (MKP-1), of which main function is to inactivate the extracellular signal-regulated kinase-1/2 (ERK-1/2), the p38 MAPK and the c-Jun N-terminal kinase-1/2 (JNK-1/2), and to exert antiproliferative and pro-apoptotic activities. However, the mechanisms underlying antiproliferative and pro-apoptotic activities of TP are not fully understood. The purpose of this study was to examine whether the down-regulation of MKP-1 expression by TP would account for antiproliferative activity of TP in immortalized HT22 hippocampal cells. Methods : MKP-1 expression and MAPK phosphorylation were analyzed by Western blot. Cell proliferation was assessed by $^3H$-thymidine incorporation. Small interfering RNA (siRNA) against MKP-1, vanadate (a phosphatase inhibitor), U0126 (a specific inhibitor for ERK-1/2), SB203580 (a specific inhibitor for p38 MAPK), and SP600125 (a specific inhibitor for JNK-1/2) were employed to evaluate a possible mechanism of antiproliferative action of TP. Results : At its non-cytotoxic dose, TP suppressed MKP-1 expression, reduced cell growth, and induced persistent ERK-1/2 activation. Similar growth inhibition and ERK-1/2 activation were observed when MKP-1 expression was blocked by MKP-1 siRNA and its activity was inhibited by vanadate. The antiproliferative effects of TP, MKP-1 siRNA, and vanadate were significantly abolished by U0126, but not by SB203580 or SP600125. Conclusion : Our findings suggest that TP inhibits the growth of immortalized HT22 hippocampal cells via persistent ERK-1/2 activation by suppressing MKP-1 expression. Additionally, this study provides evidence supporting that MKP-1 may play an important role in regulation of neuronal cell growth.