• 한국연소학회지
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• 제7권1호
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• pp.58-64
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• 2002

The bed combustion in an incinerator interacts with the gas flow region through heat and mass transfer. Combined bed combustion and gas flow simulations are performed to investigate this coupled interaction for various operating conditions and furnace configurations. Radiation onto the bed from the furnace is interrelated with the combustion characteristics in the bed, and is also affected by the flow pattern in the gas flow region. Since the contribution of gaseous emission to the total radiation is significant, an adequate flow pattern in a well-designed furnace shape would lead to an increased heat influx on the bed, especially in the early stage of the waste combustion. Advancing the initiation point of the waste combustion can also reduce the size of the lower gas temperature region above the bed, which can be achieved by controlling operating conditions such as the waste feeding rate, the bed height and the primary air flow distribution.

• 대한기계학회논문집B
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• 제24권4호
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• pp.495-503
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• 2000

The present numerical study investigates flow characteristics and heat transfer enhancement of the viscoelastic non-Newtonian fluid in a 2:1 rectangular duct. The combined effect of temperature-dependent viscosity, buoyancy and secondary flow caused by second normal stress difference are all considered. The Reiner-Rivlin model is used as a viscoelastic fluid model to simulate the secondary flow and temperature-dependent viscosity model is adopted. Three types of thermal boundary conditions involving different combinations of heated walls and adiabatic walls are considered in this study. Calculated Nusselt numbers are in good agreement with experimental results in both the thermal developing and thermally developed regions. The heat transfer enhancement can be explained by the combined viscoelasticity-driven secondary flow, buoyancy-induced secondary flow and temperature-dependent viscosity.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 1999년도 추계 학술대회논문집
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• pp.152-157
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• 1999

For the simulation of the blood flow in coronary artery, the system modeling of coronary hemodynamics is combined with CFD technique. The blood flow in coronary artery interacts with the global coronary circulation. Especially in case of the coronary artery with stenosis, the interaction plays an important role in the hemodynamics of the circulation. In this study we present a combined numerical approach using both the CFD technique for flow simulation and the global system model of coronary circulation. We use a lumped parameter model for the global simulation of coronary circulation whereas the finite element method is employed to compute the viscous flow field in stenosed coronary artery, The time variation of the pressure drop due to stenosis is obtained from the proposed numerical method. Numerical results shows that the flow resistance and pressure drop due to stenosis has a relatively large value in systole.

• Journal of Mechanical Science and Technology
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• 제18권12호
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• pp.2190-2203
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• 2004

A combined procedure for two-dimensional Delaunay mesh generation algorithm and an adaptive remeshing technique with higher-order compressible flow solver is presented. A pseudo-code procedure is described for the adaptive remeshing technique. The flux-difference splitting scheme with a modified multidimensional dissipation for high-speed compressible flow analysis on unstructured meshes is proposed. The scheme eliminates nonphysical flow solutions such as the spurious bump of the carbuncle phenomenon observed from the bow shock of the flow over a blunt body and the oscillation in the odd-even grid perturbation in a straight duct for the Quirk's odd-even decoupling test. The proposed scheme is further extended to achieve higher-order spatial and temporal solution accuracy. The performance of the combined procedure is evaluated on unstructured triangular meshes by solving several steady-state and transient high-speed compressible flow problems.

• 상하수도학회지
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• 제18권4호
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• pp.461-469
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• 2004

This research is to determine the stormwater effects on sewer concentrations by measuring and comparing the flow and pollutant concentrations during dry and rainy periods in the existing BOX type combined sewer pipes. The monitoring was carried out in two sites, which are the Daesachen outfall having PE separation wall in BOX type combined sewer pipes and the Yongunchen outfall not having seperatioin wall. The average flow-weighted BOD concentraion in Yongunchen outfall is 2-fold lower than in Daesachen outfall because of the dilution effect from ravine water. However, the pollutant mass loading is 16 fold higher in Yongunchen outfall than in Daesachen outfall because of more flows. According to the research, the separation wall controls 52% pollutant mass during a storm period (11.5 mm/hr rainfall intensity). Therefore, the Yongunchen combined sewer system (CSS) need separation wall to control and to prevent more pollutant input in stream. In Daesachen area, the maximum sewer flow rate during a storm period measured about 10 fold bigger than average sewer flow during dry periods. Also the concentrations between rainy and dry periods increase approximately 33 fold for BOD and 120 fold for SS. In Yongunchen area, it increases about 9 fold for the maximum flow rate, 18 fold for BOD and 22 fold for SS during a storm. Therefore, the research is concluded that the separation wall between stromwater (or ravine water) and sewage can decrease the dilution effect in CSS and control the pollutant loading.

• 한국물환경학회지
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• 제30권1호
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• pp.16-24
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• 2014

A combined watershed and receiving waterbody model was developed for operational water flow forecasting of the Nakdong river. The Hydrological Simulation Program Fortran (HSPF) was used for simulating the flow rates at major tributaries. To simulate the flow dynamics in the main stream, a three-dimensional hydrodynamic model, EFDC was used with the inputs derived from the HSPF simulation. The combined models were calibrated and verified using the data measured under different hydrometeological and hydraulic conditions. The model results were generally in good agreement with the field measurements in both calibration and verification. The 7-days forecasting performance of water flows in the Nakdong river was satisfying compared with model calibration results. The forecasting results suggested that the water flow forecasting errors were primarily attributed to the uncertainties of the models, numerical weather prediction, and water release at the hydraulic structures such as upstream dams and weirs. From the results, it is concluded that the combined watershed-waterbody model could successfully simulate the water flows in the Nakdong river. Also, it is suggested that integrating real-time data and information of dam/weir operation plans into model simulation would be essential to improve forecasting reliability.

• 한국통신학회논문지
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• 제16권11호
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• pp.1154-1166
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• 1991

Optical flow는 물체의 속도 결정과 추적 뿐만 아니라 영상분할과 물체의 3차원 정보로서도 중요하다. 본 논문에서는 OFF(optical flow field)의 해석 즉, OFF 분할을 위하여 3가지 모델과 결합된 피라미드 랭킹방법의 분할 알고리즘을 제시하였다. 제시된 방법에서 각 노드는 노드가 지배하는 영역내의 flow field의 모델을 형성하고, 이 영역들은 최적 적합되는 모델을 취함으로서 상위 레벨상의 노드와 결합되어진다. 또한 각 노드는 노드가 지배하는 화소들과 부모화소의 folw field 모델 사이에서 발생하는 최소제곱오차를 기초로 하여 부모화소와 링크된다. 이와 같은 방법에 의해 기존 방법들에서의 주된 문제점인 잡음에 대한 민감성을 개선할 수 있었고, 이를 실험을 통하여 입증하였다.

• PNF and Movement
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• 제18권2호
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• pp.297-303
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• 2020

Purpose: The purpose of this study was to examine the effects of inhalation and exhalation exercise combined with upper extremity proprioceptive neuromuscular facilitation pattern on two spirometry values: forced volume vital (FVC) and peak expiratory flow (PEF). Methods: Thirty-two healthy adults were divided into two groups: 1) a combined group, which performed upper extremity D2 flexion pattern (shoulder flexed/abducted/external rotated, forearm supinated, wrist radial deviated, and finger extended) during exhalation and D2 extension pattern (shoulder extended/adducted/internal rotated, forearm pronated, wrist ulnar deviated, and finger flexed) during inhalation; and 2) reverse combined group, which performed the D2 flexion pattern during inhalation and the D2 extension pattern during exhalation. The inverse application of upper extremity movements during inhalation and exhalation induced selective resistance or assistance on respiration. FVC and PEF were measured at two time points, before and after four weeks. Results: In both groups, the pre-post intervention comparison showed significant increases in FVC and PEF (p < .05). In the between-groups comparison, the reverse combined group showed a significantly higher PEF than the combined group at four weeks post intervention (p < 0.05). Conclusion: The combined respiration exercise with reverse PNF upper extremity patterns using selective resistance showed an effective increase in PEF in healthy adults. Clinicians and researchers might consider using selective resistance as a widely applicable and cost-effective option for respiratory rehabilitation planning.

• 대한기계학회논문집
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• 제18권8호
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• pp.2005-2015
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• 1994

An analytical method based on the upper bound approach for the cup-bar axisymmetric combined extrusion is presented to determine the deformation zones as well as extrusion load and deformed geometry in the early stage. A new kiematically admissible velocity field is derived by the appropriate transformation of the original velocity field and applying the flow function approach. The derived velocity field is directly related to the boundary function for the plastically deforming zones and the parameter controlling the flow direction to the forward part or backward part. Experiments are carred out with the annealed aluminum 2024 at room temperature for the various area reductions. The workhardening effect is considered in the formulation as a function of the height ratio between the deformed billet and the orighinal billet to calculate the extrusion pressures. The theoretical predictions for the extrusion loads and deformed configuration are in good agreement with the experimental results.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2003년도 The 8th Asian Symposium on Precision Forging ASPF
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• pp.193-197
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• 2003

In order to restrain the local necking during stretching of sheet metals, the combined stretching processes with simultaneous compression are proposed. The combined stretching tests with two types of compression to top of the cup were carried out using the pure aluminum sheets; (1) stroke control loading process and (2) pinpoint loading process. It was clarified that the metal flow in the cross-section of the cup is affected significantly both by the magnitude of load and the stroke in the compression process. It was also found that the local necking can be restrained effectively by the metal flow from center of the cup and therefore the forming limit is improved.