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오일근(Il Geun Oh) 한국해양공학회 1993 韓國海洋工學會誌 Vol.7 No.2
삼 자유도를 가진 부유물체의 동적 응답을 이론적으로 연구하였다. 평면내 방향 운동모우드에 대한 지배방정식을 선형화한 후, 그들의 조화해를 평면밖 방향 운동모우드의 방정식과 연성시켰다. 그렇게 해서 주어지는 방정식은 시간에 따라 변화하는 계수를 가진 형태로서, 평면밖 방향의 운동응답을 예측하는데 사용하였다. 그 결과, 평면내 방향 기진력을 받고서 같은 평면내 방향의 운동만을 보일 것으로 예측되는 부유물체가 평면밖 방향의 운동을 보일 수도 있음을 밝혔다. 동역학적 불안정성과 그 결과로 나타나는 평면밖 방향의 대진폭 운동을 보이고 있다. 본 결과는 주기적으로 동요하는 부유물체가 서로 연성된 운동을 하는 현상으로도 해석할 수 있다.
도시 하수의 생물학적 고도처리를 위한 분리막 공정의 개발 및 동역학적 계수 산정 연구
박종부(Jong Bu Park),박승국(Seung Kook Park),허형우(Hyung Woo Hur),강호(Ho Kang) 大韓環境工學會 2009 대한환경공학회지 Vol.31 No.2
본 연구는 혐기조, 안정화조, 무산소조, 막분리호기조로 구성된 membrane bioreactor의 운영을 통하여 도시 하수의 영양염류 제거 특성을 규명하였다. 수리학적 체류시간(HRT)과 슬러지 체류시간(SRT) 및 운영 여과 플럭스의 평균값은 각각 6.2시간, 34.1일과 19.6 L/m2/hr (LMH)이었으며, 공정을 운전한 결과, COD(Cr), SS, TN 및 TP의 평균 제거율은 각각 94.3%, 99.9%, 69.4% 및 74.6%이었다. 슬러지 생산계수, SDNR, SNR, SPPR 및 SPUR은 각각 0.653 kgVSS/kgBOD/d, 0.044 mgNO₃-N/mgVSS/d, 0.035 mgNH₄-N/mgVSS/d, 51.0 mgP/gVSS/d 및 5.4 mgP/gVSS/d였다. 또한, 생산된 슬러지의 평균 질소 및 인 함량은 각각 8.86%와 3.5%였다. This study was performed to investigate the characteristics of nutrient removal of municipal wastewater in membrane bioreactor system. Membrane bioreactor consists of four reactors such as the anaerobic, the stabilization, the anoxic and the submerged membrane aerobic reactor with two internal recycles. The hydraulic retention time (HRT), sludge retention time (SRT) and flux were 6.2 h, 34.1 days and 19.6 L/m2/hr (LMH), respectively. The removal efficiency of COD(Cr), SS, TN and TP were 94.3%, 99.9%, 69.4%, and 74.6%, respectively. The estimated true biomass yield, specific denitrification rate (SDNR), specific nitrification rate (SNR), specific phosphorus release rate (SPRR) and specific phosphorus uptake rate (SPUR) were 0.653 kgVSS/kgBOD/d, 0.044 mgNO₃-N/mgVSS/d, 0.035 mgNH₄-N/mgVSS/d, 51.0 mgP/gVSS/d and 5.4 mgP/gVSS/d, respectively. The contents of nitrogen and phosphorus of biomass were 8.86% and 3.5% on an average.
Moody 마찰계수식을 사용한 래버린스 실의 회전체 동역학적 해석
하태웅,Ha, Tae Woong 한국유체기계학회 1999 한국유체기계학회 논문집 Vol.2 No.3
The leakage and rotordynamic coefficients of see-through type gas labyrinth seals are determined using a two-control-volume-model analysis with Moody's wall-friction-factor formula which is defined with a large range of Reynolds number and relative roughness. Jet flow theory are used for the calculation of the recirculation velocity in the cavity. For the reaction force from the labyrinth seal, linearized zeroth-order and the first-order perturbation equations are developed for small motion about a centered position. The leakage and rotordynamic coefficient results of the present analysis are compared with Scharrer's theoretical analysis using Blasius' wall-friction-factor formula and Pelletti's experimental results. The comparison shows that the present analysis using Moody's wall-friction-factor formula and Scharrer's theoretical analysis using Blasius' wall-friction-factor formula give the same results for a smooth seal surface and the range of Reynolds number less than $10^5$.
최복록,이경로 한국기계기술학회 2013 한국기계기술학회지 Vol.15 No.5
Recently, most of moving parts at automobile engine are required to be lighter and compacter and have high performances such as strength and endurance, etc. In particular, the crankshaft is subject to complex loadings such as shear, bending, and torsional loads as well as inertia and torsional vibration. To investigate critical area and optimize the shape of crankshaft at intial design stage, it is necessary to consider the dynamic effect of crankshaft. This paper carried out structural analysis of engine crankshaft by using multi-body dynamics and multi-axial fatigue analysis
하태웅,이안성 한국소음진동공학회 1998 소음 진동 Vol.8 No.5
An analysis of lateral hydrodynamic forces of compressor labyrinth seals is presented. Basic equations are derived using a two-control-volume model for compressible flow. Blasius' wall friction-factor formula and jet flow theory are used for the calculaton of wall shear stresses and recirculation velocity in the cavity. Linearized zeroth-order and first-order perturbation equations are developed for a small motion about the centered position by expansion in the eccentricity ratio. Integraton of the resultant first-order pressure distribution over the seal defines the rotordynamic coefficients. As an application a rotordynamic analysis of the balance drum labyrinth seal found in an ethylene regrigeration copmressor is carried out. The rotordynamic characteristic results of the labyrinth seal are presented and compared with other types of seals, honeycomb seal and smooth seal.
하태웅,Ha, Tae-Woong 한국유체기계학회 2001 한국유체기계학회 논문집 Vol.4 No.2
Basic equations and their solution procedure we derived for the analysis of an annular pump seal in which the rotor has a large static displacement from the centered position. The Bulk-flow is assumed for a control volume set in the seal clearance and the flow is assumed to be completely turbulent in axial and circumferential direction. Moody's wall-friction-factor formula is used for the calculation of wall shear stresses in the control volume. For the reaction force developed by the seal, linearized zeroth-order and first-order perturbation equations are developed for small motion about an eccentric position. Flow variables are expanded by using Fourier series for the solution procedure. Integration of the resultant first-order pressure distribution along and around the seal defines the 12 elements of rotordynamic coefficients of the eccentric annular pump seal. The results of leakage and rotordynamic coefficients aye presented and compared with the Marquette's experimental results and the San Andres' theoretical analysis.