• International Journal of Aeronautical and Space Sciences
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• 제7권2호
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• pp.155-174
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• 2006

Parabolized stability equations for compressible flows in general curvilinear coordinate system are derived to deal with a broad range of transition prediction problems on complex geometry. A highly accurate finite difference PSE code has been developed using an implicit marching procedure. Compressible and incompressible flat plate flow stability under two-dimensional and three¬dimensional disturbances has been investigated to test the present code. Results of the present computation are found to be in good agreement with the multiple scale analysis and DNS data. Stability calculation results by the present PSE code for compressible boundary layer at Mach numbers ranging from 0.02 to 1.5 are also presented and are again seen to be as accurate as the spectral method.

• Wind and Structures
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• 제5권2_3_4호
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• pp.369-378
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• 2002

The application of Large Eddy Simulation (LES) in a curvilinear coordinate system to the flow around a square cylinder is presented. In order to obtain sufficient resolution near the side of the cylinder, we use an O-type grid. Even with a curvilinear coordinate system, it is difficult to avoid the numerical oscillation arising in high-Reynolds-number flows past a bluff body, without using an extremely fine grid used. An upwind scheme has the effect of removing the numerical oscillations, but, it is accompanied by numerical dissipation that is a kind of an additional sub-grid scale effect. Firstly, we investigate the effect of numerical dissipation on the computational results in a case where turbulent dissipation is removed in order to clarify the differences between the effect of numerical dissipation. Next, the applicability and the limitations of the present method, which combine the dynamic SGS model with acceptable numerical dissipation, are discussed.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2007년도 추계 학술대회논문집
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• pp.134-140
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• 2007

Nonlinear parabolized stability equations for compressible flow in general curvilinear coordinate system are derived to deal with a broad range of transition prediction problems on complex geometry. A highly accurate finite difference PSE code has been developed using an implicit marching procedure. Blasius flow is tested. The results of the present computation show good agreement with DNS data. Nonlinear interaction can make the T-S fundamental wave more unstable and the onset of its amplitude decay is shifted downstream relative to linear case. For nonlinear calculations, rather small difference in initial amplitude can produce large change during nonlinear region. Compressible secondary instability at Mach number 1.6 is also simulated and showed that 1.1% initial amplitude for primary mode is enough to trigger the secondary growth.

• Structural Engineering and Mechanics
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• 제36권3호
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• pp.279-299
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• 2010

A methodology on application of the discrete singular convolution (DSC) technique to the free vibration analysis of thin plates with curvilinear quadrilateral platforms is developed. In the proposed approach, irregular physical domain is transformed into a rectangular domain by using geometric coordinate transformation. The DSC procedures are then applied to discretization of the transformed set of governing equations and boundary conditions. For demonstration of the accuracy and convergence of the method, some numerical examples are provided on plates with different geometry such as elliptic, trapezoidal having straight and parabolic sides, sectorial, annular sectorial, and plates with four curved edges. The results obtained by the DSC method are compared with those obtained by other numerical and analytical methods. The method is suitable for the problem considered due to its generality, simplicity, and potential for further development.

• 한국수자원학회:학술대회논문집
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• 한국수자원학회 2010년도 학술발표회
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• pp.2038-2042
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• 2010

본 연구는 동해안 속초항에 정방형 직교격자체계(Regular Grid)와 직교-곡선 격자체계(Orthogonal Curvilinear Grid)를 이용하여 SWAN 모형에 적용시켜 각 격자체계에 따른 파랑변형의 특성을 비교하는데 목적이 있다. 본 연구결과 북방파제가 연장 중인 방파제 선단에서 회절현상이 관측 되었으며, 속초 해수욕장 인근에서의 해안선 형상에 따라 굴절 효과로 인하여 입사 파랑의 벡터들이 해안선에 수직하게 입사되는 현상이 관측 되었고, 특히, 조도 주변에서 파랑의 굴절 효과와 차단효과를 관찰할 수 있다. 정방형 직교 격자체계와 직교-곡선 격자체계의 계산결과는 유사하나 직교-곡선 격자체계가 해안선에서 보다 정밀한 계산 값을 얻을 수 있었다. 하지만 직교-곡선 격자체계는 계산시간이 최소 4배 이상 증가하는 단점을 가지고 있다.

• 가정과삶의질연구
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• 제11권2호
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• pp.30-39
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• 1993

This study examined the relationship between marital cohesion adaptability and marital communication and especially tested the linear versus curvilinear hypothese with Circumplex Model. The subjects were 142 couples living in Pusan./ The data were analyzed using frequency one-way ANOVA and Pearson's correlation coefficient The major finding of this study were as follows: The relationship between the dimensions of cohesion adaptability and communica-tion was linear than curvilinear. High cohesion and high adaptability spouses were more effective communication than low cohesion and low adaptability.

• Journal of the Korean Society for Industrial and Applied Mathematics
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• 제8권1호
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• pp.81-92
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• 2004

Muskhelishvili's complex variable method has been applied to derive exact and closed expressions for Gaursat's functions for the first and second fundamental problems of the infinite plate weakened by a curvilinear hole which is conformally mapped on the domain outside the unit circle by means of rational mapping function. The hole having three poles. The previous work of the authers in this domain is considered as special cases of this work.

• Water Engineering Research
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• 제1권4호
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• pp.331-342
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• 2000

• 한국경영과학회지
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• 제40권3호
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• pp.73-95
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• 2015

Firms have reexamined and restructured their supply chain based on a long-term and partnership perspective as a firm's competitive advantage increasingly relies on its supply chain capability. A number of scholar works has provided evidence to support the positive effects of supply chain collaboration; however, the relationship between collaboration and performance is still inconclusive. This study refuses to have blinded faith on supply chain collaboration, but rather this paper suggests that the contribution of collaboration to supply chain performance improvement can be limited and vary along the contextual characteristics of a buyer-supplier relationship. Moreover, we argue that the relationship between supply chain collaboration and performance can be curvilinear. This paper provides and test hypotheses regarding the relationship between supply chain collaboration and performance. By using data of the Manufacturing Panel Survey (MPS), this study empirically validates the hypotheses. Overall, the results of the study support our hypotheses about a limited contribution of supply chain collaboration to manufacturing performance, which is opposite to a conventional expectation. Particularly, the effects of supply chain collaboration differ depending on the dimensions of performance such as customer satisfaction, quality, cost, delivery, and flexibility as well as the dependency in the buyer-supplier relationship. Moreover, the results of the study indicate that supply chain collaboration and performance may have curvilinear relationships in a certain context. Through a comprehensive model and empirical evidence, this study presents a better understanding of supply chain collaboration and provokes an open discussion about the effects of collaboration. This study also provides insightful implications for managers of buyers as well as suppliers who wish to foster stronger supply chain performance via a deep buyer-supplier relationship and collaboration.

• Advances in materials Research
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• 제6권1호
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• pp.65-78
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• 2017

A hat section was designed and developed for maximum impact energy absorption and/or transmission under low velocity impact. Towards this, different hat sections, having material properties of thermoplastic, were modeled and investigated numerically using finite element analysis (FEA) in the range of 20-50 J impact energy. In the study it was experienced that the design configuration of hat section with curvilinear profile (HSCP) was excellent in energy attenuation capacity and for even distribution of maximum impact force around and along the hat section under low velocity impact loading. To validate the numerical findings, polypropylene copolymer (Co-PP) HSCP and low density polyethylene (LDPE) HSCP were developed and evaluated experimentally in the said impact energy range. A correlation was established between FEA and experimental test results, thereby, validating a numerical model to predict results for other thermoplastic materials under given range of impact energy. The LDPE HSCP exhibited better performance as compared to Co-PP HSCP in the said range of impact energy. The findings of this study will enable the engineers and technologists to design and develop low velocity impact resistance devices for various applications including devices to protect bone joints.