• Journal of the Society of Disaster Information
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• v.19 no.4
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• pp.897-907
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• 2023

Purpose: In this study, We aim to estimate a untrained person's three postures using a 2D CNN model which is trained with minimal FFT data collected by a 24GHz FMCW radar. Method: In an indoor space, we collected FFT data for three distinct postures (standing, sitting, and lying) from three different individuals. To apply this data to a 2D CNN model, we first converted the collected data into 2D images. These images were then trained using the 2D CNN model to recognize the distinct features of each posture. Following the training, we evaluated the model's accuracy in differentiating the posture features across various individuals. Result: According to the experimental results, the average accuracy of the proposed scheme for the three postures was shown to be a 89.99% and it outperforms the conventional 1D CNN and the SVM schemes. Conclusion: In this study, we aim to estimate any person's three postures using a 2D CNN model and a 24GHz FMCW radar for disastrous situations in indoor. it is shown that the different posture of any persons can be accurately estimated even though his or her data is not used for training the AI model.

• Journal of the Institute of Convergence Signal Processing
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• v.24 no.1
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• pp.15-20
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• 2023

In general, maintaining an incorrect sitting posture for a long time is widely known to adversely affect the spine. Recently, several researchers have been interested in the causal relationship between incorrect sitting posture and spinal diseases, and have been studying methods to precisely measure changes in sitting or standing posture to prevent spinal diseases. In previous studies, we have developed a sensor device capable of measuring real-time posture change, applied a momentum calculation algorithm to improve the accuracy of real-time posture change measurement, and verified the accuracy of the postural change measurement sensor. In this study, we developed a posture measurement and analysis device that considers changes in the center of body pressure through the developed sitting pressure measurement, and it confirmed the sensor as an auxiliary tool to increase the accuracy of posture correction training with improving the user's visual feedback.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.13 no.8
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• pp.3513-3520
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• 2012

This study aimed to investigate the difference of the body orientation ability in sitting position to adapt to dynamically changing angle of the base of support in stroke patients and Healthy adults. The angle between vertical and head and trunk in 12 stroke patients (6 male and 6 female) and 12 healthy adults (6 male and 6 female) were measured by video motion analysis system. The head and trunk angle between stroke patients and healthy adults in sitting position were significantly different when increase the angle of dominant side(p<.05). The head and trunk angle between stroke patients and healthy adults in sitting position were significantly different when increase the angle of non-dominant side(p<.05). The head and trunk angle between stroke patients and healthy adults in sitting position were significantly different when decrease the angle of non-dominant side(p<.05). The head angle between stroke patients and healthy adults in sitting position was significantly different(p<.05), but the trunk angle was not significantly different when decrease the angle of dominant side(p>.05), Stroke patients compared to healthy adults had more deficits in their body orientation ability in sitting position to adapt to dynamically changing angle of the base of support. This finding may help to understand postural control deficits more clearly in stroke patients in sitting position.

• Aerospace Engineering and Technology
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• v.2 no.1
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• pp.54-62
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• 2003

The satellite in space has a tiny size but is subject to the disturbance torques caused by various sources. The presence of environmental disturbance torques significantly affects the orient as well as the orbital motion of satellite. The sources of environmental effects on LEO Satellite attitude dynamics are various. Four of these, gravity gradient, Earth's magnetic field, solar radiation pressure and aerodynamic are dominant and deterministic. In this study, we describe the model of environmental disturbance torques acting on LEO Satellite and the effects of environmental disturbance torques on LEO Satellite attitude dynamics in detail.

• Proceedings of the Korean Society for Emotion and Sensibility Conference
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• 2009.05a
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• pp.161-162
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• 2009

최근 국내에서 유행하기 시작한 스키니 진(skinny jean)은 혈액순환 장애, 하복부 장기에 가해지는 압력으로 인하여 소화불량, 변비 또는 생리불순 등 여성 건강을 위협하는 의복 종류이다. 본 연구의 목적은 의복의 쾌적성을 측정할 수 있는 척도인 의복압 검사와 스키니 진의 주관적인 착용감 검사 통하여 의복의 기능적인 면에서 인체의 건강에 적합한지 분석하고자 함이다. 사이즈 코리아를 참고하여 선정한 20대 여성의 평균 사이즈에 해당하는, 인지도 높은 3개 브랜드의 청바지를 시료로 사용하여 4명의 피험자에게 착용하게 한 후, 동작을 변화시키며 변화하는 의복압을 측정하고 주관적 감각 평가를 실시하였다. 첫째, 의복압 측정결과, 엉덩이 최대 돌출 부위가 자세와 상관없이 의복압이 가장 높게 나왔고 무릎 부위 Standing 자세에서 sitting down on the floor 자세로 변할수록 의복압이 높게 나왔다. 둘째, 주관적 감각에 대한 평가 결과는 모든 자세에서 허리벨트 부위가 가장 압박감을 크게 느끼는 것으로 나타났다. 의복압과 주관적 감각의 관계분석에 있어서 스키니 진의 대부분의 부위에서 의복압이 높을수록 압박감을 느끼는 것으로 나타났으나 대퇴부 부위는 의복압이 낮은데도 불구하고 압박감을 크게 느끼는 것으로 나타났다.

• Bulletin of the Korean Space Science Society
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• 2004.04a
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• pp.56-56
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• 2004

원자외선 분광기 등, 우주관측 탑재체가 실린 과학기술위성 1호는 초기 운용과정과 자세제어에 대한 보정작업등을 거쳐 정상적인 임무를 수행하고 있다. 본 연구에서는 초기운용과 현재의 탑재체 운용 과정 중에 생성된 위성의 상태 정보 데이터를 이용하여 위성이 궤도상에서 겪는 열 변화에 대하여 어떻게 운용되고 있는지 분석하였다. 위성의 온도 데이터는 위성의 운용 및 궤도상에서 위성체의 자세와 밀접한 관계를 가지고 있다. (중략)

• Aerospace Engineering and Technology
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• v.4 no.1
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• pp.186-195
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• 2005

This paper deals with attitude control design for a thruster system which is mainly used as a control system of space vehicles. Attitude controllers are designed based on a simple blowing-down thruster system structure. In order to consider severe time-delay effects of the thruster system during controller design, the control design problem is defined based on the corresponding limit cycle analysis. Optimal roll controllers and optimal pitch/yaw controllers are resulted from co-evolutionary optimum design processes for each flight phase. The control performances are verified by computer simulations.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.37 no.5
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• pp.470-475
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• 2009

This paper is the study which is head tracker using pattern matching. Proposal algorithm obtains initial attitude of head tracker using pattern matching. Optical head tracker consists of infrared LEDs(features) which are attached helmet as pattern, stereo infrared cameras. Proposal algorithm analyzes patterns by error rate of feature distance and estimates feature characteristic number. Initial attitude of head tracker is obtained to compare map data and feature characteristic number.

• Proceedings of the KIEE Conference
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• 2005.07d
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• pp.2546-2548
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• 2005

본 논문에서는 무인항공기의 비행제어시스템 개발 및 성능분석을 위한 HILS(Hardware-in-the-Loop-Simulation) 시스템의 구축을 제안한다. 제안한 HILS 시스템은 실시간 시뮬레이션 컴퓨터(dSPACE DS1005), 3축 모션테이블, 자세 센서, 지상통제장치(GCS; Ground Control Station), 비행제어컴퓨터(FCC; Flight Control Computer)로 구성된다. 실제 신호와 유사한 신호를 발생시키기 위한 실시간 시뮬레이션 컴퓨터는 dSPACE가 담당하며, 이 신호는 비행운동을 재현을 위한 3축 모션테이블을 동작시키게 된다. 모션테이블 상에 위치하는 자세센서 값과 GCS의 명령은 FCC의 입력으로 사용된다. 구현된 HILS 시스템을 이용하여 UAV의 제어알고리즘 및 자세센서 성능 검증을 수행하였다.

• Aerospace Engineering and Technology
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• v.11 no.1
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• pp.145-157
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• 2012

The novel limit cycle analysis of the attitude control system using jet thrusters was presented based on a phase plane method by paper. It was shown in the software simulation results that the analysed results of the limit cycle was more accurate than those of the Haloulakos' method. But it was not verified in the real system. The proposed method is verified in the reaction control system for KSLV-I via an real time hardware in the loop simulation. It can be shown in this test that analyzed result of the limit cycle is very accurate.