• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2009.11a
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• pp.19-22
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• 2009

Design and performance evaluation of $H_2O_2$ monopropellant thrusters to be used at attitude control of space launch vehicles were presented in this paper. Flight model thrusters were designed after two reactors for 100, 250 Newton were conformed at engineering model. Each thruster was evaluated by measurement of characteristic velocity, thrust, specific impulse, and pulse response times.

• The Bulletin of The Korean Astronomical Society
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• v.37 no.2
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• pp.170.2-170.2
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• 2012

위성의 열진공 환경 시험은 고진공 극저온의 우주 환경을 모사하여 열제어 기능 및 임무 수행 능력을 검증하는 시험이다. 이 시험에서는 위성 주위에 부착한 방열판으로 위성 외각 온도를 변화 시켜 위성의 태양 지향 자세 또는 심우주 지향 자세를 모사하며, 이에 따른 위성의 온도 변화에 따라 지상 시험 장비로 위성의 히터 설정, 유닛 전원 형상의 변경 등을 해야한다. 또한 극고온 또는 극저온의 환경에 장시간 연속적으로 노출된 상태에서 위성의 기본적인 기능부터 영상 미션까지 검토하는 CPT 시험을 수행하며, 이 CPT 시험은 극한의 위성 상태의 시험이기 때문에 온도를 고려한 전자 시험 설계 및 24시간 위성 모니터링 시스템, 위험상황 발생 시 대처 방안 등에 대한 준비가 필요하다. 본 논문에서는 열진공 시험 시의 전자시험의 형상과 설계에 대해서 설명하고, 시험 결과에 대해서 정리하였다.

• The Journal of the Korea institute of electronic communication sciences
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• v.17 no.1
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• pp.111-118
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• 2022

In computer vision research, the two-dimensional human pose is a very extensive research direction, especially in pose tracking and behavior recognition, which has very important research significance. The acquisition of human pose targets, which is essentially the study of how to accurately identify human targets from pictures, is of great research significance and has been a hot research topic of great interest in recent years. Human pose recognition is used in artificial intelligence on the one hand and in daily life on the other. The excellent effect of pose recognition is mainly determined by the success rate and the accuracy of the recognition process, so it reflects the importance of human pose recognition in terms of recognition rate. In this human body gesture recognition, the human body is divided into 17 key points for labeling. Not only that but also the key points are segmented to ensure the accuracy of the labeling information. In the recognition design, use the comprehensive data set MS COCO for deep learning to design a neural network model to train a large number of samples, from simple step-by-step to efficient training, so that a good accuracy rate can be obtained.

• The Journal of Korean Academy of Sensory Integration
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• v.22 no.1
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• pp.25-42
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• 2024

Objective : The aim of this study was to investigate the effects of a sensory integration intervention on the sensory processing and posture control of children with developmental delays and a simultaneous family-centered coaching intervention on their parents' parenting efficacy. Methods : This study adopted a multiple probe design across four children aged five to six with developmental delays and their parents. A sensory integration intervention and a family-centered coaching intervention were employed twice a week in a total of 16 sessions over 8 weeks. Sensory profiles were evaluated, and the Korean version of the Parenting Sense of Competence was used before and after the interventions, and changes in post-intervention posture control were measured using Biorescue equipment. Results : During the intervention period, weight support in the sitting, Sitting with eyes closed, and standing positions evaluated using Biorescue was higher than two standard deviations from the baseline. After the interventions, all children showed enhanced sensory processing. Conclusion : Sensory integration and family centered coaching interventions have positive effects on the sensory processing and posture control of children with developmental delays and on their parents' parenting efficacy.

• Aerospace Engineering and Technology
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• v.8 no.2
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• pp.122-126
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• 2009

KSLV(Korea Space Launch Vehicle)-I is designed as a launch vehicle to enter a 100 kg-class satellite to the LEO(Low-Earth Orbit). Attitude angles of the upper-stage, including roll, pitch and yaw are controlled by cold gas thruster system using nitrogen gas. To verify the flow rate of the gas charging system and to prepare a nitrogen gas charging scenario, the development of a gas charging simulator for RCS(Reaction Control System) is required. This paper describes the orifice design, development, and test of the gas charging simulator for RCS of KSLV-I.

• Journal of the Korean Society for Aviation and Aeronautics
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• v.23 no.4
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• pp.125-132
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• 2015

항공기 추락 시 충돌충격단계에서 사상자가 가장 많이 발생하는 것으로 나타나고 있다. 대부분의 경우, 승객들은 두부손상으로 의식을 잃게 되어 비상탈출에 실패하여 사망에 이르게 된다. 이에 대한 대응책으로 항공기 제작사들은 내구성이 강화된 항공기 좌석을 설계 및 제작하여 설치하고 있다. 객실에서는 승객들이 충격방지자세를 취함으로써 부상을 최소화할 수 있다. 승객들에 대한 충격방지자세 안내는 모든 항공사가 시간적 여유가 있는 비상상황에서만 객실승무원이 안내방송과 함께 시범을 보이도록 절차가 수립되어 있다. 그러나 갑작스런 사고의 경우 승객들은 충격방지자세에 대한 정보를 전달받지 못한 상태에서 사상의 위험에 직면하게 된다. 본 논문은 SHEL 모델을 적용하여 승객과 사상자발생 환경, 승객과 충격방지를 위한 안전절차, 승객과 승객안전정보 전달매체, 승객과 객실승무원등의 상호작용에 내재된 위해요소를 체계적으로 규명하고 객실안전에 대한 법규 및 절차 등의 개정을 제시함으써, 항공기사고로 인한 사상자 발생에 대한 근본적인 대안을 제시하여 항공안전 증진에 기여하고자 한다.

• Journal of Digital Convergence
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• v.18 no.12
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• pp.97-103
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• 2020

The proposed system is composed of two parts, an AI physical fitness measurement part and an AI physical fitness management part. In the AI fitness measurement part, a guide to physical fitness measurement and accurate calculation of the measured value are performed through deep learning-based pose recognition. Based on these measurements, the AI fitness management part designs personalized exercise programs and provides them to dedicated smart applications. To guide the measurement posture, the posture of the subject to be measured is photographed through a webcam and the skeleton line is extracted. Next, the skeletal line of the learned preparation posture is compared with the extracted skeletal line to determine whether or not it is normal, and voice guidance is provided to maintain the normal posture.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 1998.10a
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• pp.9-9
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• 1998

다목적 실용위성의 궤도전이 및 위성체 자세제어를 위한 추진시스템의 설계요소에는 구조적 안전성, 우주환경에서의 열제어를 위한 회로 및 구성하드웨어 설계, 연료계통 맥압강하를 위한 장치설계 및 추력기 배기가스 영향을 고려한 형상설계 등이 있으며, 설계검증을 위해 부분해석이 수행된다. 또한 발사환경과 우주 궤도환경에서의 추진시스템 성능평가를 위한 연제어계 기능시험, 압력인증시험, 청정도시험 및 내부/외부 누설시험이 수행된다. 본 논문에서는 추진시스템 설계 및 조립공정에 대해 기술하였고, 시험분석을 통해 시스템의 설계 및 조립공정상의 신뢰성을 검증 분석하였다.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.37 no.1
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• pp.19-29
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• 2000

Because the previous simulation tool for attitude control of satellite was designed for the modeling of rigid body and PD controller, the attitude error can be made more than the limitation value for keeping for communication link, and then the communication link can be lost at moving of satellite. So, for rapid attitude restoration and design of stable and modernized controller, the modelling of rigid body and flexible body structure for moving GEO and LEO satellites were performed. Also the minimum time controller is designed for the rapid restoration of attitude error at communication broken and to minimize the disconnection period from ground communication system during the satellite stationkeeping. The linear regulator is designed using the space state vector that is better than accuracy and stability of PD controller. Firstly the simulation was performed for comparison of the rigid and stability of PD controller. Firstly the simulation was performed for comparison of the rigid and flexible models using PD controller and the case of the pitch angle changing by ground command, and the case of the periodic north-south stationkeeping are performed for the analysis of response characteristics of each controller when the attitude is changed. As a result, the flexible body model represents more sililar results of real situation than the rigid body model. The minimum time controller can restore 7 times rapidly than PD controller for its lost attitude. The linear regulator has several merits for capability of adaptation against the external disturbance, stability and response time. In future, we can check the estimated results using this satellite model and controller for real operation. Futhermore the development of new controller and training can be supported.

• Journal of Astronomy and Space Sciences
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• v.14 no.2
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• pp.386-394
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• 1997

In this study, a few of the modeling methods for flexible spacecraft were introduced and adopted to the modeling of a 3-axes stabilization satellite. The generated model was put into pre-built rigid body attitude control loop. A Lumped Parameter Model(Global Mode Model: GMM) was recommended for the absence of the Finite Element Method(FEM) model. Finally, GMM was compared with FEM in terms of designing a control filter. A 1st-order filter was designed to meet requirements of the controller since the new flexible model was applied, and that filter was added to motor controller and axis controller. MATLAB/Simulink was used as a tool for design and simulation of the control loop and filter.