• 한국전산유체공학회지
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• 제3권1호
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• pp.22-29
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• 1998

Parallel implementation is conducted for a SIMPLER finite volume model. The present parallelism is based on domain decomposition and explicit message passing using MPI and SHMEM. Two parallel solvers to tridiagonal matrix equation are employed. The implementation is verified on the Cray T3E system for a benchmark problem of natural convection in a sidewall-heated cavity. The test results illustrate good scalability of the present parallel models. Performance issues are elaborated in view of convergence as well as conventional parallel overheads and single processor performance. The effectiveness of a localized matrix solution algorithm is demonstrated.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 1997년도 추계 학술대회논문집
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• pp.23-28
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• 1997

A parallel implementation is made of a two-dimensional finite volume model based on the SIMPLER. The solution domain is decomposed into several subdomains and the solution at each subdomain is acquired by parallel use of multiple processors. Communications between processors are accomplished by using the standard MPI and the Cray-specific SHMEM. The parallelization method for the overall solution procedure to the Navier-Stokes equations is described in detail, The parallel implementation is validated on the Cray T3E system for a benchmark problem of natural convection in a sidewall-heated cavity. The parallel performance is assessed and the issues encountered in achieving a high-performance parallel model are elaborated.

• 한국통신학회논문지
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• 제28권4C호
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• pp.379-383
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• 2003

정규 관측량은 물론 참고 관측량을 쓰는 비모수 검파기의 검정 통계량은 정규 관측량만을 쓰는 비모수 검파기보다 더 간단하다. 부호 통계량 대신에 참고 통계량을 사용함으로써 적산성 잡음에 숨겨져 있는 확률 신호를 위한 간단한 검파기 구조를 얻을 수 있다.

• Communications for Statistical Applications and Methods
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• 제3권3호
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• pp.75-81
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• 1996

Polynomial measurement error model(MEM) with one predictor is considered. It is briefly mentioned that Chan and Mak's generalized least squares estimator(GLSE) can be derived more easily if Hermite polynomial concept is applied. It is proved that GLSE derived using new procedure is equivalent to the estimator obtained from corrected score function. Finally, much simpler proof of the asymptotic behavior of GLSE than that of Chan and Mak is provided. Much simpler formula of asymptotic covariance matrix of GLSE is a part of that proof.

• 한국항공우주학회지
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• 제33권6호
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• pp.15-20
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• 2005

타원형 실린더 주위를 흐르는 비정상 점성 유동을 해석하기 위해서 SIMPLER 방법을 사용한 이차원 비압축성 나비어-스??스 유동 해석 프로그램을 개발하였다. 실린더 직경에 대한 두께의 비가 0.6, 0.8, 1.0, 1.2인 실린더 주위의 점성 흐름을 레이놀즈 수 200, 400, 1000인 조건에서 해석하였다. 본 논문은 실린더 두께와 레이놀즈 수가 실린더에 작용하는 양력 및 항력에 미치는 영향을 파악하는데 주 관심을 두었다. 개발된 해석 프로그램의 검증을 위해서 가용한 실험 자료와 수치 해석 자료가 개발된 해석 프로그램의 수치 결과와 비교되었으며, 잘 일치하는 경향을 보여주었다. 본 연구를 통해서 실린더 두께와 레이놀즈수가 항력과 양력의 진동 주기뿐만 아니라 크기나 진폭에 큰 영향을 미치게 됨을 알 수 있었다.

• 한국항공우주학회지
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• 제33권12호
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• pp.1-8
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• 2005

타원형 실린더의 두께와 받음각 및 레이놀즈수가 실린더에 작용하는 항력과 양력에 어떤 영향을 미치는가를 고찰하기 위해서 수치적 연구를 수행하였다. 타원형 실린더 주위를 흐르는 비정상 점성 유동을 해석하기 위하여 SIMPLER 기법을 이용한 2차원 비압축성 Navier-Stokes 유동 해석 프로그램을 개발하였으며, 두께-시위길이 비가 0.2, 0.4, 0.6인 타원형 실린더 형상에 대해서 레이놀즈수가 400, 600인 조건, 그리고 받음각이 10도, 20도, 30도인 조건하에서 유동을 해석하였다. 본 연구를 통해서 실린더 두께 비와 받음각 및 레이놀즈수가 항력과 양력 계수의 시간 평균값 및 진폭의 크기, 그리고 진동 주기에 크게 영향을 미침을 확인할 수 있었다.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2007년도 춘계학술대회B
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• pp.2747-2752
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• 2007

A numerical study has been performed on the flow past a two-staged orifice in a rectangular duct. The flow field including the recirculation region behind the orifice was investigated and the pressure drop was calculated. Water was used as a working fluid and the flow was treated as the turbulent flow, of which the Raynolds number was 6000. The main parameters for the pressure drop and the recirculation region were the orifice's inclined angle against the duct, the interval between two orifices, the shape of the orifice's hole having the same area, and the change of the hole position at the same interval. The variation of the flow field was investigated with each parameter. Consequently, it was found that the most dominant parameter influencing the drop of the pressure was the change of the hole position at the same interval between orifices. Especially when the interval between orifices was narrow and the relative position the holes was changed, its effect to the flow field was shown most drastically as a result of this study. The SIMPLER algorithm with FLUENT code was employed to analyze the flow field.

• East Asian mathematical journal
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• 제9권2호
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• pp.275-282
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• 1993

• Journal of Mechanical Science and Technology
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• 제20권1호
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• pp.167-175
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• 2006

A parametric study has been accomplished to figure out the effects of elliptic cylinder thickness, angle of attack, and Reynolds number on the unsteady lift and drag forces exerted on the elliptic cylinder. A two-dimensional incompressible Navier-Stokes flow solver is developed based on the SIMPLER method in the body-intrinsic coordinates system to analyze the unsteady viscous flow over elliptic cylinder. Thickness-to-chord ratios of 0.2, 0.4, and 0.6 elliptic cylinders are simulated at different Reynolds numbers of 400 and 600, and angles of attack of $10^{\circ},\;20^{\circ},\;and\;30^{\circ}$. Through this study, it is observed that the elliptic cylinder thickness, angle of attack, and Reynolds number are very important parameters to decide the lift and drag forces. All these parameters also affect significantly the frequencies of the unsteady force oscillations.

• 전자공학회논문지B
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• 제33B권11호
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• pp.83-96
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• 1996

On PR-IV magnetic recording systems, the maximum likelihood sequence detection (MLSD) method is optimum. But it has the problem of the complexity of the structure. The three level detection (TLD) method can be used, which has simpler structure than MLSD, but requires almost twice of power to achieve the same probbility of error as MLSD does. Therefore a new detection method (error controlled detection: ECD) is proposed which has much simpler structure than MLSD and gives much better performance than TLD. The simulation resutls show that the performance of ECD is better than that of TLD by approximaterly 0.5~1.3dB both in linear and nonlinear channels.