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정사각단면 $180^{\circ}C$ 곡덕트에서 층류진동유동의 유동 특성에 관한 연구
박길문,조병기,봉태근,Park, Gil-Mun,Jo, Byeong-Gi,Bong, Tae-Geun 대한기계학회 1998 大韓機械學會論文集B Vol.22 No.2
In the present study, the flow characteristics of developing laminar oscillatory flows in a square -sectional 180 deg. curved duct are investigated experimentally. The experimental study using air in a square-sectional 180 deg. curved duct is carried out to measure velocity distributions with a data acquisition and LDV (Laser Doppler Velocimetry) processing system. In this system, Rotating Machinery Resolver (RMR) and PHASE program are used to obtain the results of unsteady flows. The major flow characteristics of developing oscillatory flows are found by analyzing velocity curves, mean velocity profiles, time-averaged velocity distribution of secondary flow, wall shear stress distributions, and entrance lengths. In a lower dimensionless angular frequency, the axial velocity distribution of laminar oscillatory flow in a curved duct shows a convex shape in a central part and axial symmetry. The maximum value of wall shear stress in a lower dimensionless angular frequency is located in an outside wall, but according to increasing the dimensionless angular frequency, the maximum of wall shear stress is moved to inner wall. The entrance lengths of laminar oscillatory flows in a square-sectional 180 deg. curved duct is obtained to 90 deg. of bended angle of duct in this experimental conditions.
장천학,김현돈,조병기,이장우,Jang, Cheon Hak,Kim, Hyeon Don,Jo, Byeong Gi,Lee, Jang U Korean Chemical Society 1995 Bulletin of the Korean Chemical Society Vol.16 No.1
Interpolymer complex formation between basic polypeptide poly(L-proline) Form Ⅱ (PLP(Ⅱ)) and acidic polypeptides poly(L-glutamic acid) (PLGA) and poly(L-aspartic acid)(PLAA) has been studied in water-methanol (1:2 v/v) mixed-solvent by viscometry, potentiometry, light scattering and circular dichroism (CD) measurements. It has been found that polymer complexes between PLP(Ⅱ) and PLGA (or PLAA) are formed via hydrogen bonding with a stoichiometric ratio of PLP(Ⅱ)/PLGA (or PLAA)=1:2 (in unit mole ratio) and that PLP(Ⅱ) forms polymer complex more favorably with PLGA than with PLAA. In addition, the minimum (for pH 5.0) and the maximum (for pH 3.2) in reduced viscosity of dilute PLP(Ⅱ)-PLGA mixed solutions are observed at 0.67 unit mole fraction of PLGA (i.e., [PLP(Ⅱ)]/[PLGA]=1/2). These findings could be explained in terms of molecular structure (or conformation) of the complementary polymers associated with the complex formation.
잠수함용 어뢰기만기 발사체계 안전장치 작동성능 향상에 관한 연구
장호성 ( Ho-seong Chang ),서대수 ( Dae-su Seo ),이경찬 ( Gyeong-chan Lee ),이종관 ( Jong-gwan Lee ),조병기 ( Byeong-gi Jo ),김중배 ( Joong-bae Kim ) 한국품질경영학회 2018 품질경영학회지 Vol.46 No.3
Purpose: The purpose of this study is to improve submarine TACM launcher system safety device performance. Methods: In this study, EPLD(Electrically Programmable Logic Device) control and time sharing method to the safety device actuator motor and discrete signal processor in launch control panel were used to resolve unusual performance of safety system. Results: The result of this study are as follows; First, sporadic stopping of safety device actuator motor due to insufficient In-Rush current was resolved. Second, repeat of safety device condition as lock & release due to chattering for motor activating was resolved. Third, simultaneous release function for safety device actuator was available. Conclusion: The unusual performance of function for submarine TACM launcher system was overcame by applying EPLD control and time sharing method. The suggestions were proved by performance test in the pressure chamber. The results of this study enhanced survivability of ○○○ class submarine from enemy torpedo.