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곡관덕트에서 난류맥동유동의 축방향 속도분포와 2차유동속도분포
손현철,이홍구,이행남,박길문 한국마린엔지니어링학회 2000 한국마린엔지니어링학회지 Vol.24 No.6
In the present study, flow characteristics of turbulent pulsating flow in the square-sectional $180^{\circ}$curved duct are investigated experimentally. In order to measure axial direction velocity and secondary flow distributions, experimental studies for air flow are conducted in the square-sectional $180^{\circ}$curved duct by using the LDV system with the data acquisition and the processing system of the Rotating Machinery Resolver (RMR) and the PHASE software. The experiment is conducted on seven sections form the inlet($\phi=0^{\circ}$) to the outlet($\phi=180^{\circ}$) at $30^{\circ}$intervals of the duct. The results obtained from the experimentation are summarized as follows : In the axial direction velocity distributions of turbulent pulsating flow, when the ratio of velocity amplitude (A1) is less than one, there is hardly any velocity change in the section except near the wall and in axial velocity distribution along the phase. The secondary flow of turbulent pulsating flow has a positive value at the bend angle of $150^{\circ}$regardless of the ratio of velocity amplitude. The dimensionless value of secondary flow becomes gradually weak and approaches zero in the region of bend angle $180^{\circ}$without regard to the ratio of velocity amplitude.
손현철,김경진 한국구조생물학회 2017 Biodesign Vol.5 No.2
meso-Diaminopimelic acid decarboxylase from Corynebacterium glutamicum (CgDAPDC) is the key enzyme for theproduction of L-lysine and it catalyzes meso-DAP to produce the final product, L-lysine. The CgDAPDC was overexpressedand purified to homogeneity by Ni-NTA affinity and size-exclusion chromatography. The CgDAPDC protein was crystallizedusing sitting-drop vapor-diffusion method in the presence of 0.8 M sodium citrate tribasic and 0.1 M sodium cacodylate,pH 6.5 at 293 K. X-ray diffraction data were collected to a maximum resolution of 2.4 Å. The crystal belonged to spacegroup P21212, with unit cell parameters a = 114.54 Å, b = 91.702 Å, c = 95.161, α = β = γ = 90°. With one molecules perasymmetric unit, the crystal volume per unit protein mass was 2.64 Å3 Da-1, which correspond to a solvent content ofapproximately 53.37%.
곡관덕트에서 난류정상유동의 벽면전단응력분포와 입구길이에 관한 실험적 연구
손현철,이홍구,김대욱,김명호,박길문 朝鮮大學校 機械技術硏究所 2000 機械技術硏究 Vol.3 No.1
In this paper, an experimental investigation of characteristics of developing turbulent steady flows in a square-sectional 180°curved duct is presented. The experimental study using air in the square-sectional 180°curved duct is carried out to measure entrance length and wall shear stress distributions by using Laser Dopper Velocimeter(LDV) system with data acquisition and processing the system of FIND6260 software at 7 sections from the inlet(ø=0°) to the outlet(ø=180°)in 30°intervals of the curved duct. The results obtained from experimental studies are summarized as follows : (1) The critical Dean number of turbulent steady flow is about 560. (2) The value of the wall shear stress becomes minimum in the inner wall and gradually increases toward the outer wall where it becomes maximum. (3) The entrance length of the turbulent steady flow is shorter than that of the traditional steady flow, reaching the vicinity of bend angle 90°
가진 펌프에 연결된 곡관 출구의 직관에서 난류진동유동의 속도분포와 전단응력분포
손현철,이행남,박길문 대한기계학회 2002 大韓機械學會論文集B Vol.26 No.10
In the present study, velocity profile and wall shear stress distributions of developing turbulent oscillatory flows in an oscillator connected to straight duct located in exit region of a curved duct was investigated experimentally. The experimental study for air flows was conducted to measure axial velocity profiles, shear stress distributions by using the Laser Doppler Velocimetry(LDV) system with the data acquisition and processing system of Rotating Machinery Resolver(R.M.R) and PHASE software. The results obtained from experimental studies are summarized as follows. The critical Reynolds number for a change from transitional oscillatory flow to turbulent flow was about 7500, in the 60region of dimensionless axial position which was considered as a fully developed flow region. The turbulent oscillatory flow, velocity profiles of the inflow period in the entrance region were gradually developed, but those of the outflow period were not changed nearly. Velocity profiles of inflow and outflow were shown as a symmetric form in a fully developed flow region. The wall shear stress distributions of turbulent oscillatory flow increase rapidly as the flow proceeds to downstream and flow was in good agreement with the theoretically.