• International Journal of Aeronautical and Space Sciences
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• 제16권2호
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• pp.295-310
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• 2015

In the present study, an unstructured mixed mesh flow solver was used to conduct a numerical prediction of the aerodynamic performance of the S-76 rotor in hover. For the present mixed mesh methodology, the near-body flow domain was modeled by using body-fitted prismatic/tetrahedral cells while Cartesian mesh cells were filled in the off-body region. A high-order accurate weighted essentially non-oscillatory (WENO) scheme was employed to better resolve the flow characteristics in the off-body flow region. An overset mesh technique was adopted to transfer the flow variables between the two different mesh regions, and computations were carried out for three different blade configurations including swept-taper, rectangular, and swept-taper-anhedral tip shapes. The results of the simulation were compared against experimental data, and the computations were also made to investigate the effect of the blade tip Mach number. The detailed flow characteristics were also examined, including the tip-vortex trajectory, vortex core size, and first-passing tip vortex position that depended on the tip shape.

• 한국환경복원기술학회지
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• 제16권1호
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• pp.17-25
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• 2013

The mechanical properties appeared at the concrete mixed with Polypropylene fiber($1kg/m^3$, $3kg/m^3$, $5kg/m^3$) are compared with normal concrete and wire mesh one and evaluated. Achieved slump test to search effect that PP fiber gets to workability, even if the mixing amount of fiber increases, confirmed that slump value is no change almost. The no difference can be caused by hard mixture, but because of the big softness of fiber there is no effect greatly up to PP fiber mixing amount $5kg/m^3$ even with soft mixture. Compressive strengths and flexural strengths of the concretes with PP fiber and without the fiber are appeared almost alike. If examine load resistance ability by PP fiber mixing amount increase, it could know that the increase of fiber mixing amount improves load resistance ability and the toughness index is increased. While normal concrete is broken at the same time with crack, fiber mixed concrete stand in flexure load continuously after crack occurrence. In compare with wire mesh embeded concrete, wire mesh mixed concrete stands in some degree in flexure load by wire mesh crack occurrence and the test piece was broken at the same time. But, it could know that the PP fiber mixed concrete resist continuously to flexure load in bigger displacement.

• 대한치과교정학회지
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• 제23권1호
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• pp.101-113
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• 1993

For the purpose of interpretation of positional changes of craniofacial structures in Class III malocclusion between mixed and permanent dentition, 73 normal samples and 103 Class III samples of mixed dentition and 125 normal samples and 168 Class III samples of permanent dentition were selected. Comparative cephalometric analysis was undertaken between them respectively by mesh diagram method to evaluate the positional changes of maxilla and mandible in anteroposterior direction and vertical direction and also the inclination changes of maxillary and mandibular incisors in labio-lingual direction. The following results were obtained : 1. The antero-posterior positional changes of the maxilla and mandible were posterior direction of maxilla and anterior direction of mandible. 2. The vertical positional changes of the maxilla and mandible were superior direction of both maxilla and mandible. 3. The labio-lingual inclination changes of the maxillary and mandibular incisors were lingual direction of both maxillary and mandibular incisors.

• 한국초지조사료학회지
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• 제38권1호
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• pp.61-73
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• 2018

본 연구는 중부지역 $35^{\circ}$ 경사의 절개지에서 초종, 혼파조합 및 그물망 설치에 따른 초지의 생산성, 식생변화 및 사료가치를 조사하여 신속한 초지조성에 적합한 방법을 찾는데 목적이 있다. 본 시험은 2014년에 중부지역 $35^{\circ}$내외의 절개지에 초지를 조성하여 2015년과 2016년의 월동 후 생육특성, 식생변화, 목초 생산성 및 사료가치를 확인하였다. 초종별에서 주구는 그물망의 유 무로 두었으며, 세구는 TF, PRG 및 RT의 3가지 초종이었다. 혼파조합별에서 주구는 그물망의 유 무로 두었으며, 세구는 혼파조합 3가지로서 처리구 A는 OG위주, 처리구 B는 TF위주 및 처리구 C는 PRG 위주였다. 그물망(방조망 이용)은 일반 농가에서 간단하게 구비할 수 있는 그물망을 3겹으로 처리하였다. 월동 후 생육에서 초종별은 목초 피복도 측면에서 TF 단파가 유리하였으며 혼파조합별은 차이가 없었다. 또한 그물망의 처리는 초종 및 혼파조합별에서 모두 목초의 피복도를 높이는 것으로 나타나 초기정착에 긍정적인 영향이 있었다. 초지식생 변화에서 초종별은 초기정착과 이후 예취에도 지속적으로 목초 피복도를 유지하였던 TF 단파가 유리하였으며, 혼파조합별은 목초 피복도를 지속적으로 유지한 OG 및 TF 위주가 유리하였다. 또한 그물망의 처리는 초종 KBG 및 RT 단파와 혼파조합 PRG 위주에서 잡초의 비율을 낮추는 효과가 있었다. 목초 생산성에서 초종별은 TF 및 KBG 단파가 우수하였으며, 혼파조합별은 처리구간 유의적인 차이가 없었다. 초종별의 사료가치는 조성 1년차에서 CP 함량으로 KBG 및 RT 단파가, NDF 및 ADF 함량으로 TF 단파가 우수하였으며, 조성 2년차는 차이가 미미하였다. 혼파조합별은 조성 1년차에서 사료가치의 차이가 없었으나, 조성 2년차는 PRG 위주의 혼파조합이 NDF, ADF 및 TDN이 양호하게 나타났다. 또한 그물망을 처리하는 것은 초종 및 혼파조합 처리에서 모두 차이가 없었다. 이상을 종합하면 중부지역 $35^{\circ}$ 경사의 절개지에서 초종은 TF 단파가 초기목초 피복도가 높고 지속적으로 식생을 유지하였으며, 혼파조합은 OG 및 TF 위주가 지속적으로 식생을 유지하여 유리한 것으로 나타났다. 또한 그물망을 처리하는 것은 목초의 초기정착과 그 이후 식생변화에도 긍정적인 영향이 나타났다.

• Structural Engineering and Mechanics
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• 제42권5호
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• pp.701-713
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• 2012

Results pertaining to 3D investigations on the effect of the thickness on the stress fields at the crack front are presented. A 3D finite element analysis is performed using a modified single edge-notched tension specimen configuration, with an inclined crack to include mixed mode I-II. A technique to mesh the crack front (3D) with singular finite elements in ANSYS without using third party software is introduced and used in this study. The effect of the specimen thickness is explicitly investigated for six thicknesses ranging from 1 to 32 mm. In addition, three crack inclination angles, including pure Mode-I, are used to study the effect of mixed-mode I-II fracture. An attempt is made to correlate the extent of a particular stress state along the crack front to thickness. In addition, ${\sigma}_{zz}/{\nu}({\sigma}_{xx}+{\sigma}_{yy})$ contours at the crack front are presented as a useful means to analyze the stress state.

• 한국농공학회지
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• 제37권2호
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• pp.21-30
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• 1995

In order to save time and efforts in generating finite element meshes in irregular houndaries of domains, it is needed to develop an automatic mesh-generator which can hoth promote the accuracy of solutions and reduce the run-time in operating finite ele- ment models. In this study, the advancing front technique of triangular mesh generation and the transforming technique from triangular meshes to quadrilateral meshes were used to de- velop a computer program for the automatic triangular and quadrilateral meshes in the mixed shape. Furthermore, to enhance the quadrilateral mesh quality, the techniques of Laplancian smoothing and interior mesh modification were employed. The mesh genera- tor was applied to evaluate its applicability to irregular and complex geometries such as Nakdong river bay. In has hoen shown that the automatic mesh generator developed is capable of automatically generating meshes for irreguiar and complex geometries with high qualities of meshes and with the simple input data of arbitrarily specified nodal spacing in bound- aries.

• 한국식품저장유통학회지
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• 제9권3호
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• pp.309-314
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• 2002

홍화씨의 식품재료로서의 이용성을 증가시키기 위한 목적으로서 양갱의 주원료인 건조 팥소 분말에 대한 볶은 홍화씨 분말 20, 35, 45 및 60mesh별로 첨가한 제품과 홍화씨 45mesh분말의 첨가량을 0, 5, 10, 15 및 20%로 하여 제조한 제품 및 배합수로 녹차추출물을 이용한 제품의 품질특성을 조사하였다. 수분함량은 20mesh 체분리 분말 첨가 제품에서 가장 낮은 27.6% 이었고, 동일한 45mesh 분말의 첨가량에 따른 양갱제품의 수분함량은 분말의 첨가량이 증가할수록 증가하는 경향을 보였다. 수분활성도는 60mesh 홍화씨 분말 첨가 제품에서 0.93로 가장 높았고, 45mesh분말의 첨가량에 따른 수분활성도는 분말의 첨가량이 증가할수록 높아지는 경향이었다. 색도는 분말의 mesh 수가 증가할수록 L값과 a값이 다소 낮아지는 경향이었고 반대로 b값은 다소 증가하였다. 동일한 입자크기를 가진 분말의 첨가량 증가에 따른 L, a 및 b값은 전반적인 증가현상을 보였다. 또한, 조직감 특성 중 견고성과 부숴짐성은 홍화씨 분말의 입도가 미세한 첨가구가 상대적으로 증가하였고 동일한 입도를 가진 홍화씨 분말 첨가량이 증가함에 따라 견고성과 부숴짐성은 증가하였고, 접착성과 탄력성은 감소하는 경향을 나타내었다. 관능평가에서도 전반적기호도, 조직감 및 부숴짐성이 홍화씨 분말의 입도가 미세한 첨가구가 상대적으로 증가하는 결과를 보였고, 증류수를 배합수로 제조한 제품과 증류수와 녹차추출물을 1:1로 혼합하여 제조한 제품에서 거의 같은 수준의 높은 관능점수를 얻었다.

• Current Optics and Photonics
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• 제1권4호
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• pp.325-335
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• 2017

Hybrid radio frequency/free space optical (RF/FSO) wireless mesh networks have attracted increasing attention for they can overcome the limitations of RF and FSO communications and significantly increase the throughput of wireless mesh networks (WMNs). In this article, a resource assignment optimization scheme is proposed for hybrid RF/FSO wireless mesh networks. The optimization framework is proposed for the objective of maximizing throughput of overall hybrid networks through joint transmission slot assignment, FSO links allocation and power control with the consideration of the fading nature of RF and FSO links. The scheme is formulated as an instance of mixed integer linear program (MILP) and the optimal solutions are provided using CPLEX and Gurobi optimizers. How to choose the appropriate optimizer is discussed by comparing their performance. Numerous simulations are done to demonstrate that the performance of our optimization scheme is much better than the current case of having the same topology.

• Journal of applied mathematics & informatics
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• 제28권5_6호
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• pp.1035-1054
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• 2010

We consider a mixed type singularly perturbed one dimensional elliptic problem with discontinuous source term. The domain under consideration is partitioned into two subdomains. A convection-diffusion and a reaction-diffusion type equations are posed on the first and second subdomains respectively. Two hybrid difference schemes on Shishkin mesh are constructed and we prove that the schemes are almost second order convergence in the maximum norm independent of the diffusion parameter. Error bounds for the numerical solution and its numerical derivative are established. Numerical results are presented which support the theoretical results.

• 한국경영과학회지
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• 제30권1호
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• pp.1-15
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• 2005

In this paper, we deal with a mesh network design problem arising from the deployment of WDM for the optical internet. The mesh network consists of mesh topology for satisfying traffic demand while minimizing the cost of WDM, OXC, and fiber cables. The problem seeks to find an optimal routing of traffic demands in the network such that the total cost is minimized. We formulate the problem as a mixed-integer programming model and devise a tabu search heuristic procedure. Also we develop an optical internet design system that implements the proposed tabu search heuristic procedure. We demonstrate the computational efficacy of the proposed algorithm, compared with CPLEX 8.0.