• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2011.11a
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• pp.666-669
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• 2011

The rupture disc shapes of bulkhead type pulse separation device(PSD) are designed for new dual pulse rocket motor. Before final design PSD, that three different rupture disc are tested and confirmed the performance of the discs. Through analyzing the test results the PSD decides, two rupture disc shapes with flow holes of eight circles and eight trapezoids.

• The Journal of the Acoustical Society of Korea
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• v.12 no.1
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• pp.12-19
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• 1993

진동시험 동안 구조물은 진동시험기로부터 높은 진동에너지를 받게 되는데 공급되는 에너지를 시험물에 전달하기 위해서는 시험물에 따라 다양한 종류의 진동시험치구가 필요하게 된다. 이중에서 T-형상 진동시험치구는 진동시험축에 대해 3방향으로 시험물을 설치할 수 있고, 형상이 간단하며, 또한 값이 저렴하므로 많은 설계자들은 T-형상 치구를 설계하여 사용한다. 그러나 이 치구는 수직판이 어떤 주파수에서 평판처럼 공진현상을 일으키기 때문에 동역학적으로 설계하기가 어렵다. 본 논문에서는 진동시험치구의 기능을 향상시키기 위해 모우드 시험(Model Testing)기법을 사용하는 방법과 시험결과를 근거로 설계변경을 위해 수직보강판, 수평보강판, 그리고 천연 고무패드를 사용하여 이것들이 치구의 동특성에 미치는 영향을 기술하며 그 결과를 치구설계 때 응용 가능하도록 한다.

• Proceeding of EDISON Challenge
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• 2013.04a
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• pp.343-348
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• 2013

초임계 익형은 천음속 영역에서 비행하는 상업용 민간 항공기와 전투기 날개의 공력성능을 향상시키기 위해 Whitcomb R. T.가 제안 하였다. 초임계 익형은 상부표면을 평평하게 디자인하여 임계마하수보다 큰 마하수에서 나타나는 익형 주위의 충격파 출현을 지연시킴으로써 항력을 줄일 수 있고, 상부 표면의 평면 설계로 인한 양력 감소를 보정하기 위하여 하부 표면의 꼬리부분에 캠버가 있는 형상을 하고 있다. 본 연구에서는 EDISON CFD를 이용하여, 초임계 익형의 공력특성을 해석하고 Xfoil의 data와 비교 분석하였다. 또한, 초임계 익형의 형상을 변경하여 두께와 뒷전 캠버가 다른 초임계 익형을 설계하였다. 새로운 초임계 익형의 형상은 상용 프로그램 Maple12을 이용하여 Whitcomb Integral Supercritical Airfoil의 형상을 수정하여 구할 수 있다. 초임계 익형 주위의 유동을 2D압축성 유동으로 가정하고 EDISON CFD의 2D_Comp-2.0 솔버를 사용하여 수치해석을 수행하였다.

• Proceedings of the Korea Information Processing Society Conference
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• 2008.11a
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• pp.219-222
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• 2008

3차원 인체 스캐너로부터 얻어진 인체형상데이터는 여러 인체에 대한 3차원 평균 모델을 만들어 내는 등의 통계적 분석이나 자세 변경을 위해 필요한 내부 골격 구조와 골격과 피부조직 사이의 관계 등을 계산해 내기 어렵다. 또, 이러한 통계적 분석을 위해서는 각 모델 간의 상응 관계가 확립되어야 하지만 스캐너로부터 얻어진 인체 형상 데이터들은 측정 환경이나 대상에 따라 각각이 서로 상이한 기하학적 구조로 이루어져 있다. 본 논문에서는 템플릿 모델을 3차원 인체데이터에 맞도록 변형함으로써 다수의 인체 형상에 대하여 토폴로지를 일치시키도록 한다. 3차원 인체 데이터에 대해 템플릿 모델이 가장 근사한 형상이 되도록 하는 변형을 자동으로 찾아내기 위해서 표면 위에 정의된 특징점들을 사용한다. 또한, 기존에 찾아둔 특징점군 및 변형정보 데이터가 충분히 많다면 새로운 변형을 계산하는 데 유용하게 사용될 수 있음을 보인다. 이렇게 상응 관계가 확립된 모델들은 삼차원 벡터 공간의 점들의 집합으로 표현 및 통계적 분석이 가능하게 된다.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.25 no.1
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• pp.37-49
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• 2012

A structural model of the SNF(spent nuclear fuel) disposal canister for the PWR(pressurized water reactor) for about 10,000 years long term deposition at a 500m deep granitic bedrock repository has been developed through various structural safety evaluations. The SNF disposal baskets of this canister model have the array type whose four square cross section baskets stand parallel to each other and symmetrically with respect to the center of the canister section. However, whether this developed structural model of the SNF disposal canister is optimal is not determinable yet. Especially, there is still a problem in weight-reduction of the canister. The cross section shape of the SNF basket should be changed to solve this problem. There are two ways in changing the cross section shape of the SNF basket; the one is to rotate the cross section itself and the other is to change the cross section shape as other shape different from the square cross section. The previous study shows that the canister with $30{\sim}35^{\circ}$ rotated basket array is structurally more stable than the canister with un-rotated parallel basket array. However, whether this canister with rotated basket array is optimal is not either determinable as yet, because it is not revealed that the canister with other cross section different from the square cross section is structurally more stable than other canisters. Therefore, the structural analysis of the SNF disposal canister with other cross section shape which is also symmetric with respect to the canister center planes is very necessary. The structural analysis of the canister with various cross section shape basket array in which each basket is arrayed symmetrically with respect to the center planes is carried out in this paper. The structural analysis result shows that the SNF disposal canister with circular cross section shape baskets located symmetrically with respect to the center of the canister section is structurally more stable than the previously developed SNF disposal canister with the parallel basket array.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.36 no.8
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• pp.790-796
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• 2008

Typical solid rocket motors have a fixed propellant grain shape and nozzle throat size resulting in a fixed motor thrust. Pintle nozzle has been suggested as a means of providing variable thrust while maintaining the inherent advantage of solid rocket motors. In this study, the pintle shape effect on nozzle performance is investigated using experimental-aided Computational Fluid Dynamics(CFD). The pintle shape is modified by a principle of monotony. CFD analysis is performed using Fluent by applying the turbulent model. This analysis indicates that nozzle thrust and pintle load are influenced by change of nozzle shock pattern and flow separation due to pintle shape and there exists a high-performing pintle shape.

• Aerospace Engineering and Technology
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• v.9 no.2
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• pp.51-56
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• 2010

There are two main software in COMS ground station at the normal mode operation - stationkeeping and wheel off-loading. In this paper, ground software validation test for wheel off-loading is summarized and described. The wheel off-loading was performed the design change from E3000 heritage and analyzed. The wheel off-loading of ground software has two part; one is wheel off-loading management for parameters change at the thruster set switching time and the other is wheel off-loading set-point being sent to satellite for the reference momentum.

• Journal of Advanced Marine Engineering and Technology
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• v.19 no.3
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• pp.42-49
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• 1995

In this study, the optimum structural modification of the L-type structure by shape changes is suggested. The vibration characteristics of L-type structure are analyzed by the sub-structure synthesis method, and the coordinte sensitivities of each sub-structure are calculated and the change quantities of the positions to be modified are suggested by using the coordinate sensitivities. The results obtained are as follows : 1. The sensitivities of the natural frequency could be calculated by the sensitivity analysis. 2. The change quantities of the position to be modified could be suggested by the optimum structural modification method. 3. The developed program could reduce the process and time of computation, since the sensitivity was directly calculated by differential method, not finite difference method.

• Journal of the Korean Society of Propulsion Engineers
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• v.23 no.5
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• pp.107-114
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• 2019

In many military aircraft, s-shaped diffusers are used to prevent the fan blades of the turbofan engine from being exposed to the outside. The inlet configurations of the air intakes for military aircraft vary, such as the rectangular intake of the F-22, the crescent-like intake of the F-16, elliptical intake of the MQ-25. In this study, the aerodynamic performance of s-shaped diffusers with various inlet configurations was evaluated using numerical analysis. In addition, the configuration of the middle section of an s-shape duct was changed to the crescent shape, and the effects on its aerodynamic performance were investigated. As a result, there was a slight difference in total pressure recovery according to various inlet configurations with ellipse-shaped middle sections. Also, the total pressure distortion was the lowest in the rectangular inlet shape. When the configuration of the middle section was changed from an ellipse to a crescent shape, the total pressure recovery remained at a high level, except for the ellipse-shaped inlet configuration. In terms of total pressure distortion, the duct with the crescent-shaped middle section showed a significantly more uniform pressure distribution than that with the ellipse-shaped middle section.

• Journal of the Korean Society of Marine Environment & Safety
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• v.24 no.4
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• pp.467-474
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• 2018

The purpose of this study is related to automatic hull-form design for ships operating at two speeds. Research was conducted using a series 60 ($C_B=0.6$) ship as a target, which has the most basic ship hull-form. Hull-form development was pursued from the viewpoint of improving resistance performance. In particular, automatic hull-form design for a ship was performed to improve wave resistance, which is closely related to hull-forms. For this purpose, we developed automatic hull-form design software for ships by combining an optimization technique, resistance prediction technique and hull-form modification technique, appling the software developed to a target ship. A sequential quadratic programming method was used for optimization, and a potential-based panel method was used to predict resistance performance. A Gaussian-type modification function was developed and applied to change the ship hull-form. The software developed was used to design a target ship operating at two different speeds, and the performance of the resulting optimized hull was compared with the results of the original hull. In order to verify the validity of the program developed, experimental results obtained in model tests were compared with calculated values by numerical analysis.