• Defense and Technology
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• no.8 s.294
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• pp.72-81
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• 2003

해외 파병시마다 매번 거론되어 온 전개형의무시설은 무기체계측면에서 신규첨단 전력의 연구개발을 위한 장기적인 투자가 긴요하다고 판단한다. 대내저기으로 한반도내 작전지역 뿐만 아니라 재해재난시 신속 전개를 위한 다목적 의료시설이 요구되는 곳에 설치 활용할 수 있는 전개의무시설 개발 여건개선이 이뤄져야 할 것이며, 대외적으로는 세계평화에 기여하고, 한국군 위용을 과시할 수 있는 전개형의무시설을 확보하여 의무전력을 확대하여 나가야 겠다.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.30 no.7
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• pp.11-19
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• 2002

Inflating characteristics of the parachute canopies have been experimentally investigated with the objective of measuring the parachute opening parameters such as canopy filling time and the peak opening force using scaled parachute models. A device has been made and tested to eject a model parachute into a wind tunnel flow and to measure the drag force acting on it. The force-time histories and the peak opening force are obtained, and these comparative aerodynamic characteristics were analyzed and discussed, including the effect of forebody wake. The opening of the ringslot parachute model appeared to be faster than that of the available similar data by about 10~40%, and fair to good agreement was obtained for the reefed ribbon parachute.

• Journal of Satellite, Information and Communications
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• v.3 no.1
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• pp.29-34
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• 2008

After spacecraft is separated from the launch vehicle, first of all spacecraft deploy the solar array. Solar array deployment is one of the key factors deciding the success of the spacecraft mission. Therefore, It is necessary to predict the solar array deployment motion and check the safety through calculating the load on the tape hinges of solar array using the deployment analysis in the initial design phase. In this paper, solar array deployment analysis is performed by multi-body dynamics simulation program. From the analysis results, assessment on the safety also is carried out. In addition, hinge characteristic test is fulfilled to find out hinge characteristic, and is applied to the deployment analysis.

• Journal of the Korean Society of Radiology
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• v.83 no.2
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• pp.360-371
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• 2022

Purpose This study aimed to assess the factors influencing aortic unfolding (AU) defined by aortic width on coronary artery calcium (CAC) scan and determine the normal limits for AU. Materials and Methods In this retrospective study, we measured AU in 924 asymptomatic subjects who underwent CAC scanning during routine health screening from June 2015 to June 2018. Multivariate regression analysis was used to evaluate the factors influencing AU. After the exclusion of subjects with risk factors associated with AU, 283 subjects were included in the analysis of normal values of AU. Mean AU, standard deviation, and upper normal limit were calculated. Results Sex, age, CAC score, body mass index, body surface area, hypertension, left ventricular hypertrophy, plasma creatinine, and smoking were significantly associated with AU. The mean AU was 102.2 ± 12.8 mm for men and 93.1 ± 10.7 mm for women. AU increased with advancing age (9.6 mm per decade). Conclusion AU determined from a single measurement on CAC scans was associated with cardiovascular risk factors. The normal limits of AU were defined by age, sex, and body surface area in low-risk subjects in this study.

• Journal of the Korea Institute of Military Science and Technology
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• v.11 no.3
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• pp.161-168
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• 2008

The deployable space structure is necessary to minimize the satellite volume and launch cost. For the deployment, passive deployment mechanism has widely been used to attenuate a latch shock induced when the structure is just fully deployed. To reduce the latch shock, viscous damper is applied to the passive deployment mechanism and it can control the deployment speed of the structure. In this paper, dynamic analysis of the deployable space structure using the passive deployment mechanism with the viscous damper has been performed. The viscous damping values have been optimized through numerical simulation. The satellite's attitude influenced by pyro activation for the release of the structure has also been investigated.

• The Bulletin of The Korean Astronomical Society
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• v.37 no.2
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• pp.136.1-136.1
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• 2012

저궤도지구관측 위성의 태양전지판은 위성이 궤도에 진입하고나서 전개된 후 위성에 전력을 공급하는 임무를 전담하는 중요 시스템이다. 이러한 시스템이 정상적인 임무 수행을 위해서는 우주 환경에서의 원활한 전개가 필수적이다. 따라서 위성은 발사이전 개발과정에서 태양전지판에 대한 전개성이 완벽히 검증되어야 한다. 이를 위해 무중력 조건을 모사하는 별도의 시험 장치를 활용하여 태양전지판의 전개 시험이 실시된다. 본 논문에서는 저궤도지구관측위성용 태양전지판의 비행모델에 대하여 실시한 전개 시험 방법 및 분석 내용을 소개하고자한다.

• KLA journal
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• v.45 no.6 s.349
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• pp.42-44
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• 2004

이번 도서관문화 6월호에서는 최근 ‘기억투쟁과 문화운동의 전개’라는 책을 공동 집필하여 주목받았던 서울대학교 사회학과 정근식 교수를 만나, 사회적 기억의 중요성과 기억 보존을 위한 투쟁과정에서 전개되는 문화운동과 관련한 도서관의 역할 등을 내용으로 대화를 나누었다.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.42 no.8
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• pp.701-706
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• 2014

In these days, there have been numerous researches on nano and micro satellites under the slogan of "Faster, Smaller, Better, Cheaper". Since optical structure occupies large portion of satellite volume, research on deployable optical structure gains great attention to reduce total volume of the satellite. In this paper, we establish the requirement of deployable optical structure based on specification of conventional optical structure and propose two candidate mechanisms which can satisfy the degree of deployment precision. Then, in order to evaluate the degree of deployment precision, we carry out kinematic analysis on de-space among tilt, de-space and de-center which influences optical characteristic of a satellite.

• Applied Chemistry for Engineering
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• v.9 no.2
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• pp.200-206
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• 1998

The effect of surface tension and viscosity of polymer solution on the thickness of water casting membranes was studied. Spreading of polymer solutions on water surface was governed by the surface tension and viscosity of the polymer solution. The thickness of water casting membrane was affected by these two factors. The properties, mentioned above, were proportional to the polymer concentration. The order of magnitude in surface tension was PVC>PS>CA and that of viscosity was CA>PS>PVC. The difference of surface tension between water and polymer solution acts as driving force for spreading of polymer solution, but the viscosity as resistance. The thickness of polymeric membrane prepared by water casting was PS>CA>PVC. The order of membrane thickness was not as same as that of surface tension. This phenomena were due to the viscosity which acts as more effective spreading resistance than the surface tension.

• Journal of Aerospace System Engineering
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• v.16 no.3
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• pp.63-72
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• 2022

The purpose of this paper was to understand the dynamics of deployment of large mesh antennas, and to provide a numerical method for determining the dynamic stiffness and the driving forces for the design. The deployment structure was numerically modeled using the frame elements. The eigenvalue analysis was demonstrated, with respect to the folded and unfolded configurations of the antenna. A multibody dynamic model was formulated with Kane's equation, and simulated using the pseudo upper triangular decomposition (PUTD) method for resolving the constrained problem. Based on the multibody model, the kinetics of the deployment, the motor driving forces, and the feasibility of the designed deployment structure were investigated.