• Journal of the Society of Naval Architects of Korea
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• v.37 no.2
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• pp.70-76
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• 2000

A numerical study on the viscous flow around a 2-dimensional circulation control foil is carried out for application on the field of naval architecture and ocean engineering. The governing equations are the RANS and the continuity equations. The equations are discretized by finite difference method and MAC method and the pressure poisson equation is calculate by a SOR method and an O-type non-staggered boundary fitted coordinate system which is overlapped near the slot is used to improve the numerical accuracy. Turbulence is approximated by a modified Baldwin-Lomax turbulence model. In the present paper, the Coanda effect on a 2-dimensional foil of a 20% thickness ellipse with modified rounded trailing edge has been numerically studied. The change in drag and lift of the foil with various jet momentums are calculated and compared to the experimental results to show good agreements.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.46 no.1
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• pp.10-17
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• 2018

The size of commercial wind turbines has been increased. Generally, the pitch control is used to increase the efficiency of wind turbine. However, the pitch control has difficulty to control the local unsteady flow control which makes fatigue load and decreases the efficiency. In this research, Synthetic Jet Actuators(SJAs) are manufactured and applied into a wing section to delay flow separation and increase aerodynamic performances. The SJAs as a kind of zero-net mass-flux actuators injects and removes fluid through a small orifice with a given frequency. The SJA modules actuated by piezoelectric disks are manufactured and the aerodynamic performances are measured according to the shape of the orifice and the velocity of the jets through the wind tunnel test. It is confirmed that as the velocity of the jets are increased using rectangular shape orifice, drag force is decreased and lift force in increased.

• Journal of Environmental Health Sciences
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• v.10 no.1
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• pp.55-65
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• 1984

韓國內 9個道別 地域 가운데 5個道의 駐韓美軍事地域에서 39個의 誘蚊燈에 의하여 2,114 Trap night를 稼動하여 2년동안 채집하여 얻은 결과는 다음과 같다. 1. 3屬, 14種, 65,847마리의 암모기가 收集되었으며 금빛 숲모기, 중국 얼룩날개 모기, 빨간 집모기, 작은 빨간 집모기가 가장 넓게 분포되어 主種을 이루었다. 2. 작은 빨간 집모기가 수집된 전체 암모기의 55.4%를 차지하였으며 5개도 전역에 걸쳐 분포되었으나 90% 이상이 평택지역에서 수집되었다. 이 종은 7월부터 수집되기 시작하여 8월에 가장 높은 개체군 밀도를 나타내고 9월부터 감소한다. 1982년 채집된 모기수는 1981년 모기수의 5배에 達했다. 3. 중국 얼룩 날개 모기는 수집된 전체 암모기수의 28.2%를 나타냈고 5월부터 散發的으로 나타나서 7,8월에 높은 개체군 밀도를 보이고 9월부터 감소한다. 1981년과 1982년의 채집된 모기수는 큰 差異를 나타내지 않았다. 4. 금빛 숲모기는 수집된 전체 암모기수의 8.8%를 나타냈고 5개도 전역에 걸쳐 발생하나 주로 지방에서 수집되었다. 이 종은 5월부터 나타나서 6월에 가장 높은 개체군 밀도를 보이고 그후부터 감소하는 경향을 보이나 8월에 다시 조금 높은 발생을 나타내나 6월의 그것에 비하여 낮다. 5. 빨간 집모기는 전체 암모기수의 5.3%를 차지하였고 5개도 전역에 여름에 걸쳐 고루 분포되었다. 6. Anopheles lesteri는 평택지역에서 네마리가 채집되었으나 이 종은 중국 얼룩 날개 모기와 형태학적인 區分이 어려워서 더욱 면밀한 考察이 필요되어지며 나머지 9종의 모기는 매우 적은 수가 채집되었다. 7. 살충제와 모기 驅除法에 관하여 간락하게 논의되었다.

• Transactions of the Korean Society of Mechanical Engineers
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• v.17 no.6
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• pp.1621-1632
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• 1993

A numerical simulation is carried out on flows in a rotating serpentine flow passage, which models a cooling passage in a gas turbine blade, by using a 3-D FVM based TURBO-D program. When it is rotating, the flow field exhibits quite different aspects due to the effect of the Coriolis force. Especially the secondary flow field appearing in the cross-sectional area is very complex because of the combined effect of the Coriolis force and the centrifugal force in the curved area. Local Nusselt numbers are also obtained based on the Reynolds analogy and compared with the published experimental data showing a good agreement. The results of the present study can be applied to the design of cooling passages of a gas turbine blade.

• Journal of the Korean Society for Marine Environment & Energy
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• v.12 no.1
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• pp.9-14
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• 2009

A numerical investigation was performed based on the Reynolds-Averaged Navier-Stokes(RANS) equations for the two-dimensional unsteady flow around a vertical axis turbine(VAT) with three or four blades. VAT is one of the promising devices for tidal current energy conversion. The geometry of the turbine blade was $NACA65_3$-018 airfoil, for which CFD analysis using Fluent was carried out at several angles of attack and the results were compared with the corresponding experimental data for validation and calibration. Then CFD simulations were carried out for the whole vertical axis turbine with a two-dimensional setup. The CFD simulation demonstrated the usefulness of the method to study the typical unsteady flows around VATs and the results showed that the optimum turbine efficiency could be achieved for carefully selected combinations of the number of blade and Tip-Speed Ratio(TSR).

• Journal of Conservation Science
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• v.26 no.4
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• pp.417-427
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• 2010

This study is to examine the manufacturing technique based on scientific investigation and analysis on Steel-Plated Jewel Beetle's Adornment gilt-bronze openwork remains excavated from No. 100 site at Hwango-dong Gyeongju. As a result of the investigation on the manufacturing revealed that riveting was adopted to connect gilt-bronze openwork plates and steel plates, followed by mercury amalgam plating method and carving of the patterns by means of the dotted line engraving technique. There were some traces on the surface of Jewel Beetle wings that show the use of pins for fixing, which seems to be the result of recycling or processing. The sectional analysis shows the high possibilities that varnishing with lacquer was adopted for wing adhesion, and it was confirmed that varnishing with lacquer was used on the strap pendant plate to prevent corrosion.

• Journal of the Korean Society of Propulsion Engineers
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• v.4 no.3
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• pp.29-37
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• 2000

Because the previous design procedure for the composite wind turbine blade structure using trial and error method takes long time, a improved design procedure by using the program based on classical laminate theory was proposed to reduce the inefficient element. According to the improved design procedure, limitation of strains, stresses and displacements specified by international standard specification IEC1400-1 for the composite wind turbine blade were applied to sizing the structural configuration by using the rule of mixture and the principal stress design technique with a simplified turbine blade. Structural safety for strength and buckling stability was confirmed by the developed analysis program based on the laminate theory to minimize the design procedure. After modifying the preliminary design result with additional structural components such as skin, foam sandwich and mounting joints, stresses, strains, displacements, natural frequency, buckling load and fatigue life were analyzed by the finite element method. Finally these results were confirmed by comparing with IEC1400-1 specification.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.47 no.1
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• pp.59-65
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• 2019

In this study, optimal design of direct-drive VCMs (Voice Coil Motor) for a missile fin actuator is carried out. The torque performance and the characteristics of the VCM are predicted by commercial electromagnetic analysis software, ANSYS Maxwell. The optimal design is obtained at the minimum and maximum actuating angles where the aerodynamic load acting on the fin is the largest in the operating range. The critical variables of the actuator is designed and the RSM (Response Surface Method) is used for the optimization. The response surface model consists of second-order functions and its experimental points are selected by a central composite design. This design is widely used for fitting a second-order response surface. The adjustment regression coefficients is computed for adequacy checking of the response surface model. Finally, the torque values obtained by the RSM and the ANSYS Maxwell are shown in good agreement.

• Korean journal of applied entomology
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• v.56 no.4
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• pp.319-329
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• 2017

We investigated the host preference of Ricania app. at different developmental stages to select the effective control methods. Ricania spp. at different developmental stages preferred different host plants. During the nymphal period, individuals moved to the bottom due to environmental factors such as wind and rain, rather than inhabiting trees, and fed on various plants ranging from 1 year-old herbaceous plants to shrubs. Especially, at Palbong Mt. in Gonju, Ricania spp. nymphs preferred Symplocos chinensis f. pilosa, Celastrus orbiculatus, Euonymus alatus, Kalopanax septemlobus, Aralia elata, Styrax japonicas, Rubus parvifolius, Ru. coreanus, Ru. crataegifolius, Quercus acutissima, Cornus officinalis, Lespedeza bicolor, Albizia julibrissin, L. maximowiczii, Rhododendron schlippenbachii and Rh. indicum. At Yongbong Mt. in Hongseong, Ricania spp. adults preferred herbaceous plants, such as Helianthus annuus, Solanum nigrum, and Oenothera biennis rather than trees during the pre-oviposition stage. Subsequently, as the oviposition season began, Ricania spp. adults were rarely found in H. annuus, S. nigrum, or O. biennis and appeared to migrate to the perennial trees and shrubs hosts to lay eggs. At Palbong Mt., the main laying hosts of Ricania spp. adults were Weigela subsessilis, Ailanthus altissima, Q. aliena, Boehmeria platanifolia, Diospyros lotus, Ziziphus jujubae var. inermis, St. japonicus, Prunus mume, P. serrulata var. spontanea, Spiraea prunifolia f. simpliciflora, Ru. crataegifolius, Salix koreensis, Ru. yedoense f. poukhanense, and Co. controversa. The degree of egg laying, number of egg masses and adult Ricania spp. were significantly higher in sunlit areas than in shaded areas, in addition, the lower the altitude, the more adults were present. This study contributes toward the development of traps that can attract and control Ricania spp. and reduce the density of Ricania spp. that disturb the ecosystem.

• Monthly Korean Chicken
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• s.136
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• pp.71-73
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• 2006

2003년말 발병한 조류인플루엔자의 파동을 이겨내고 1년 9개월이라는 최단기간에 화의종결을 이뤄내 완전한 경영정상화를 이룬 체리부로가 7개월여만에 제 2의 도약을 위한 힘찬 날개짓을 시작했다. 올해로 창사 15주년을 맞이하는 (주)체리부로(대표이사 김인식)는 지난 9월 7일 충북 진천 본사에서 지역 국회의원 등 정관계 인사와 관련 단체 및 업체 대표, 체리부로 농가협의회장 및 회원농가 등 약 1천여명이 참석한 가운데 하루 30만수의 닭을 가공할 수 있는 신축공장 준농식을 갖고, 본격 가동에 들어갔다.