• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.34 no.11
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• pp.18-25
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• 2006

Unsteady aerodynamic force measurements were carried out in order to investigate the effects of phase difference of a dragonfly-type model with two pairs of wing. A load-cell was employed to measure the aerodynamic force generated by a plunging motion of the dragonfly-type model. The dragonfly-type model has a dynamic similarity with real one, and incidence angles of fore- and hind-wing are 0° and 10°, respectively. Other experimental conditions are as follows: The freestream velocity was 1.6 m/sec and corresponding chord Reynolds number was 2.88×103, and phase differences of fore- and hind-wing were 0°, 90°, 180° and 270°. The variation of aerodynamic coefficients during one cycle of the wing motion is presented. Results show that the lift is generated during the downstroke motion and the drag generated during the hind-wing‘s downstroke motion with the lift generation.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.30 no.6
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• pp.107-115
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• 2002

A parametric study has been conducted to evaluate the effects of finite element modeling methods on the internal loads, sizing and the weight of the multi-spar aircraft wing structures. The wing is idealized into total 18finite element models and subjected to 4typical external load conditions. An automatic sizing algorithm based on MSC/NASTRAN and MSC/PATRAN is developed. The results show that the critical part affection the internal loads and weight of the structure is wing skin. Effect of modeling of the spar and rib on the structural behavior is not manifest. On the contrast to the general expectation, the models using the bending-resistant elements show the heavier weight than ones by the elements without bending stiffness. From this results, designers of multi-spar wing are recommended to construct the finite element model considering the bending stiffness, or to check the characteristics of the structure before modeling.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.39 no.1
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• pp.50-55
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• 2011

In this study, simultaneous aero-structural design was performed for HALE aircraft wing. The span and the shape of main spar were considered as design variables. To maximize aerodynamic performance and to minimize weight, multi-objective optimization was used. Nonlinear static aeroelastic analysis was performed to compute large deflection of wing. Design of experiment and response surface method were used to reduce computation cost in the design process. Also, aerodynamic performances of deformed wing and rigid wing were compared.

• Journal of the Society of Naval Architects of Korea
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• v.30 no.1
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• pp.30-44
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• 1993

This paper deals with both experimental and theoretical methods for performance prediction of asymmetric stater propulsion systems which have been used for the purpose of recovery of a propeller slipstream rotational energy due to a stator located in front of the propeller. Using the developed computer code based on the lifting surface theory, theortical investigation on the interaction between the stator and the propeller is provided in order to obtain general insight on the performance characteristics of the propulsion systems in uniform and non-uniform flow. Such theoretical calculations have end agreements with model Inset results. The asymmetric stator would give an efficiency gain of about 6% to the compound propulsor system compared with the single propeller system.

• Korean journal of applied entomology
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• v.33 no.3
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• pp.194-200
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• 1994

An annotated list of 33 species belonging to the famil~es Stathmopodidae (7 including 2 unrecorded species), Bamchedridae (a new species: Batrnchedra koreano sp n.), Blastodacnidae (3 including an unrecorded species), and Cosmopterigidae (22 species) from the Korean peninsula is given. For Cosmopterigidae. continuing from the previous artlcle (Park, 1994), 2 species (Cosmopterix bichrorne- 110 sp, n. and Labdio antenello sp. n.) are described as new and 2 species are newly added to the fauna, and all available informations on host plant of lama with a list of all known species in Korea are provided.

• 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.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.32 no.3
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• pp.74-81
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• 2004

In this study preliminary structural design has been performed to develop an all composite wing box for experimental aircraft(classified in FAR Part 21). Considerations on composite materials and their manufacturing process were taken into account throughout the design phase. Aerodynamic loads were estimated by using Shrenk method(NACA TM No 948) and FAR Part 23 Appendix A. The structural layout has been determined to carry effectively the critical loads and to maximize the benefit of composite structure. Maximum strain failure allowable and first ply failure criteria were applied for the sizing of major structural members. Finally, the designed composite wing box structure is presented in the form of drawings, which include material specifications, stacking sequences and joint design.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.44 no.1
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• pp.1-11
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• 2016

The information about the deformations of high-aspect-ratio wings is needed for the real-time monitoring of structural responses. Wing deformation in flight can be predicted by using relationship between the curvatures and the strains on the wing skin. It is also necessary to consider geometric nonlinearity when the large deformation of wing is occurred. The strain distribution on fixed-end is complex in the chordwise direction because of the geometric shape of fixed-wings on fuselages. Hence, the wing displacement can be diversely predicted by the location of the strain sensing lines in the chordwise direction. We conducted a study about prediction method of displacements regardless of the chordwise strain sensing locations. To correct spanwise strains, the ratio of spanwise strain to chordwise strain, Poisson's ratio, and the ratio of the plate strain to the beam strain were used. The predicted displacements using the strain correction were consistent with those calculated by the FEA and verified through the bending testing.

• Journal of the Korea Concrete Institute
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• v.27 no.5
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• pp.541-549
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• 2015

This study was conducted to experimentally investigate the seismic retrofitting performance of non-ductile reinforced concrete (RC) frames by introducing engineered cementitious composite (ECC) wing panel elements. Non-ductile RC frame tested in this study were designed and detailed for gravity loads with insufficient or no consideration to lateral loads. Therefore, Non-ductile RC frame were not satisfied on present seismic code requirements. The precast ECC wing panels were used to improve the seismic structural performance of existing non-ductile RC frame. A series of experiments were carried out to evaluate the structural performance of ECC wing panel elements alone a non-ductile RC frame strengthened by adding ECC panel elements. Failure pattern, strength, stiffness and energy dissipation characteristics of specimens were evaluated based on the test results. The test results show that both lateral strength and stiffness were significantly improved in specimen strengthened than non-ductile RC frame. It is noted that ECC wing wall elements application on non-ductile RC frame can be effective alternative on seismic retrofit of non-ductile building.

• Korean journal of applied entomology
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• v.60 no.1
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• pp.99-103
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• 2021

This study was conducted to investigate the hatching rate of Pochazia shantungensis according to the treatment method of machine oil and the effect on apple quality by spawning. In the effect of machine oil treatment, when 20 times of the machine oil was spread by brush, the average hatching rate was 0.57%, and the sprayed branches showed an average hatching rate of 1%. When the machine oil agent was applied 50 times, the hatching rate was about 35% to spread by brush, whereas the spray treatment showed about 77%, so there were no difference from the non-treatment considering the deviation. There was no statistically significant difference in the quality of fruit even when apple fruits were fruited in the following year in the results of spawning and non-spawning of P. shantungensis in Hongro and Fuji varieties. In addition, there was no statistical significance in the difference between branch breakage and growth caused by spawning of P. shantungensis.