• Transactions of the Korean Society of Mechanical Engineers
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• v.19 no.8
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• pp.2039-2050
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• 1995

The nonlinear low-Reynolds-number k..epsilon. model of park and Sung is extended to predict the turbulent heat transports in separated and reattaching flows. The equations of the temperature variance( $k_{\theta}$ and its dissipation rate(.epsilon.$_{\theta}$ are solved, in concert with the equations of the turbulent kinetic energy(k) and its dissiation rate(.epsilon). In the present model, the near-wall effect and the non-equilibrium effect are fully taken into consideration. The validation of the model is then applied to the turbulent flow behind a backward-facing step and the flow over a blunt body. The predicted results of the present model are compared and evaluated with the relevant experiments.

• Proceedings of the SAREK Conference
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• 2009.06a
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• pp.415-420
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• 2009

Selective Catalytic Reduction(SCR) has been used for the reduction of $NO_x$ in a steam supply boiler. Recently, the reduction of $NO_x$ becomes an important research field because of its negative effect on an environment. Shape optimization of circular poles installed in the chamber, which is located in upstream of a SCR, has been performed using response surface method and three-dimensional Navier-Stokes analysis to enhance gas flow uniformity. Three design parameters, diameter, arranging angle and stretching ratio of circular poles, are considered in the present study. Throughout the shape optimization of a circular pole, gas flow uniformity is successfully increased by decreasing local recirculation flow in a square duct chamber. Recirculation flow observed in the corner of the square duct can be reduced by proper installation of a guide vane or a blunt body. Detailed flow characteristics are also analyzed and discussed.

• Journal of Chest Surgery
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• v.28 no.2
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• pp.218-220
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• 1995

This 51 years old male patient was admitted to the department of thoracic and cardiovascular surgery via OPD because of anterior chest pain. 7days before admission, He got the chest trauma after traffic accidents,the lateral chest roentgenogram showed complete transverse sternal fracture. He also complained of mild dyspnea. We also noticed that he had depressed anterior chest wall. It looks like funnel chest. The operative findings revealed dislocated & callus formations at the both 4th and 5th costochondral junction and transverse fracture of sternal body between 4th and 5th costochondral junction, the upper end of sternal fracture was situated below the lower end of sternal fracture. The two ends of sternal fracture were situated at the same level and reapproximated the two ends by two-interrupted wire sutures. The patient is well on the road to recovery after the operation.

• 한국전산유체공학회:학술대회논문집
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• 1999.11a
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• pp.42-47
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• 1999

In this study, we adopt the point symmetric Gauss-Seidel relaxation algorithm to obtain the steady state solution of the Navier-Stokes equations for the thermal and chemical nonequilibrium flow of air. All of the inviscid, viscous flux Jacobians and thermochemical source Jacobians are included in the implicit part Numerical simulation is performed for the thermal and chemical nonequilibrium flow over blunt body and computational results are presented. The convergence history and CPU time of the present computation are compared with the LU-SGS scheme which employs the approximate Jacobians.

• 한국전산유체공학회:학술대회논문집
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• 2005.04a
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• pp.128-134
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• 2005

In the CFD area, the numerical analysis of high Mach number flow over a blunt-body poses many issues. Various numerical schemes have been developed to cover the issues, but the traditional schemes are still used widely due to the complexities of new schemes and intricacy of modifying the established codes. In the present study, the well-known Roe's FDS based on TVD-MUSCL scheme is used for the solution of very high Mach number three-dimensional flows posing carbuncle and non-physical phenomena in numerical analysis. A parametric study was carried out to account for the effects of the entropy fixing, grid configurations and initial condition. The carbuncle phenomena could be easily overcome by the entropy fixing, and the non-physical solution could be eliminated by the use of the modified initial condition regardless of entropy fixing and grid configurations.

• Journal of Mechanical Science and Technology
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• v.18 no.12
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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.

• Proceeding of EDISON Challenge
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• 2012.04a
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• pp.37-40
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• 2012

EDISON CFD 수치 해법 기법을 바탕으로 초음속 유동장 속에서 spike가 부착된 무딘 물체에 대하여, spike 형상 변화에 따른 압축성 효과에 의한 항력 변화 추이를 고찰하였다. Spike의 길이 따른 항력 변화 추이를 살펴보았다. Spike의 길이가 Main body와 특정한 비율을 가질 때 항력이 최소가 된다. 이를 기준으로 spike 길이가 특정 길이만큼 줄어들거나 늘어날 경우에 각각 1.35%, 4.95% 항력이 증가하였다. 이러한 자료들은 초음속 유동장에서 무딘 물체에 가해지는 압축성 효과에 의한 저항을 최소화하기 위한 spike 설계 시 중요한 견해를 제공한다.

• Bulletin of the Society of Naval Architects of Korea
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• v.23 no.2
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• pp.14-20
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• 1986

Through the momentum considerations, added resistance of a ship in regular waves are studied within the framework of the linear potential theory for a ship moving with a constant mean forward speed. In this paper, added resistance in head waves with comparably small wave length is focused by modifying the Marou's method. The strength of the singularities for the Kochin function is modified by considering the diffraction potentials. Slender body theory is used to determine the diffraction potentials as Adachi did. The response of a ship motion is found by using new strip method. For the purpose of comparison with the present method, calculation was also conducted by Marou's and Gerritsma-Beukelman's method. Numerical calculations are performed for five different models, that is, series 60(Cb=0.6, 0.7, 0.8), S7-175 container ship and blunt bow model. Numerical results obtained by the present method show relatively good corelations comparing with experimental results in the region under considerations.

• Journal of the Society of Naval Architects of Korea
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• v.35 no.1
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• pp.15-23
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• 1998

Characteristics of turbulence beneath the free surface around a blunt bow are numerically-investigated. Three dimensional wavier-Stokes and continuity equations are solved for the simulations.. The Large Eddy Simulation(LES) with the external disturbance is performed to simulate the turbulent free surface flow called sub-breaking wave. The result shows that the free surface fluctuates beyond a certain critical condition and the characteristics of the fluctuation are similar to the turbulent boundary layer flow around a solid body.

• Archives of Craniofacial Surgery
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• v.18 no.4
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• pp.264-268
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• 2017

The zygomaticomaxillary complex (ZMC) functions as a buttress for the face and is the cornerstone to a person's aesthetic appearance, by both setting the midfacial width and providing prominence to the cheek. Malar deficiency is often acquired by blunt injury incurred in a traumatic accident, resulting in ZMC fracture. A 48-year-old male patient presented a right ZMC fracture after contusion injury by a baseball. He only received conservative management and later he suffered discomfort during mouth opening at the moment of mastication, due to trismus involving the temporomandibular joint. In the current case, we describe a surgical technique, by which the malar body is shifted anteriorly and laterally after combined oblique-vertical osteotomy. The technique presented, eventually restored the former aesthetic position of the malar complex and symmetry, and, moreover, improved mastication function.