• The Journal of the Acoustical Society of Korea
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• v.28 no.2
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• pp.135-140
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• 2009

In this paper, we synthesized active sonar target signals based on highlights model, and then carried out target classification using the synthesized signals. If the target aspect angle is changed, the different signals are synthesized. To know the result, two different experiments are done. First, The classification results with respect to each aspect angle are shown. Second, the results in two group in aspect angle are acquired. Time domain feature extraction is done using matched filter and envelope detection. It shows the pattern of each highlights. Artificial neural networks and multi-class SVM are used for classifying target signals.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.27 no.8
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• pp.1331-1337
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• 2003

Linearized equations of motion for the vibration analysis of rotating cantilever plates with arbitrary orientation angle are derived in the present work. Two in-plane stretch variables are introduced to be approximated. The use of the two in-plane stretch variables enables one to derive the equations of motion which include proper motion-induced stiffness variation terms. The equations of motion are transformed into dimensionless forms in which dimensionless parameters are identified. The effects of the dimensionless parameters on the modal characteristics of rotating cantilever plates are investigated through numerical study. The natural frequency loci veering along with the associated mode shape variations, which occur while the rotating speed increases, are also presented and discussed.

• Proceedings of the Korean Society of Fisheries Technology Conference
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• 2000.10a
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• pp.27-28
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• 2000

일반적으로 과학어군탐지기는 임의의 수층에서 어군에 의해 산란된 신호로부터 자원량 추정을 실시한다. 따라서, 대상 어군을 구성하는 개체어의 표적강도(Target Strength ; TS)는 가장 중요한 변수이며, 이로부터 현장에서 어군의 분포 밀도를 좀더 정확하게 추정할 수 있다. TS를 결정하는 변수는 자세각, 어체의 체장, 부레의 유무, 주파수 등이다. TS를 알기 위한 많은 국내ㆍ외의 실험들이 죽은 어체를 이용하였으며, 살아있는 어체라도 음축으로부터 어체의 위치를 정확히 파악하기 어려운 센서들을 사용하여 정확한 TS의 정보를 제공하는데는 한계가 있었다. (중략)

• Journal of the Korean Institute of Intelligent Systems
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• v.20 no.5
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• pp.677-682
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• 2010

This paper addresses a method of estimating roughly the human pose by comparing Haar-wavelet value which is learned in face detection technology using AdaBoost algorithm. We also presents its application to face recognition. The learned weak classifier is used to a Haar-wavelet robust to each pose's feature by comparing the coefficients during the process of face detection. The Mahalanobis distance is used to measure the matching degree in Haar-wavelet selection. When a facial image is detected using the selected Haar-wavelet, the pose is estimated. The proposed pose estimation can be used to improve face recognition speed. Experiments are conducted to evaluate the performance of the proposed method for pose estimation.

• Aerospace Engineering and Technology
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• v.4 no.1
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• pp.66-76
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• 2005

In this study, star visibility analysis of a star tracker is performed by using a statistical apprach. The probability of the Sun and the Earth proximity, the solar array masking probability, and the solar array blinding probability by the Sun light are obtained from the arbitrary chosen satellite positions as a function of a line of sight vector of the star tracker in several satellite attitude modes. This analysis demonstrates that the optimized star tracker accomodations can be determined to be an elevation angle -40o and two azimuth angles $-35^{circ}$ and $-150^{circ}$.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.38 no.5
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• pp.437-444
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• 2010

This paper deals with the attitude control of an underactuated spacecraft that has one single-gimbal variable-speed CMG. An underactuated spacecraft may not converge to arbitrary attitudes if its total angular momentum is not zero. To stabilize a spacecraft, the CMG has to align with the angular momentum in the inertial frame. Four different install configurations for the CMG have been considered and controllable angular momentums have been analyzed. Also, based on the backstepping method, stabilizing control laws have been presented and their properties have been compared.

• Journal of the Korea Convergence Society
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• v.9 no.12
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• pp.123-128
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• 2018

The aim of this study was to determine the effects of the action observation and visual feedback on the alignment, pain and function of forward head posture(FHP) and round shoulder(RS). A total of 24 participants with FHP and RSP were randomly assigned to general exercise(GE, n=8), action observation(AO, n=8), and visual feedback(VF, n=8). All subjects were exercised three times a week for four weeks. The groups were assessed for craniovertebral angle(CVA), round shoulder posture(RSP), visual analog scale(VAS), and neck disability index(NDI) before and after exercise, There was a significant difference in CVA in the GE, AO and RSP, VAS and NDI were significantly different in all groups. AO was more effective than GE, VF for VAS. The results of this study suggest that action observation may be effective to improve the FHP and RS.

• The Journal of Korean Academy of Prosthodontics
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• v.49 no.1
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• pp.38-48
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• 2011

Purpose: Dentists suffer back, neck and shoulder pain during their careers due to bad operating posture. If dentists have a good operating posture ergonomically, there would be less pain and discomfort in the shoulder and back. Therefore, dentists should learn the Home position which enables dentists to approach a stable posture ergonomically. This study was to compare tooth preparation in the Home position and the Random position, and evaluate the clinical efficacy of the Home position. Materials and methods: Tooth preparation for fixed partial denture was performed on the maxillary left 2nd premolar and maxillary left 2nd molar at the two different operating positions were compared. The amount of occlusal reduction, marginal width, subgingival margin depth, and convergence angle were measured. A T-test was performed separately to compare the results of the Random position and the Home position. Results: 1. The amounts of average thickness of occlusal reduction on fossa were deficient to the ordered ones in the Random position and the Home position (P > .05). 2. The average subgingival margin depth of prepared margin on maxillary left 2nd premolar, maxillary left 2nd molar were excessive in the Random position than in the Home position. On the maxillary left 2nd premolar, there was no statistical difference in the Random position and the Home position except Distal midline, DL line angle, Lingual midline, ML line angle (P< .05). On the maxillary left 2nd molar, there was no statistical difference in the Random position and the Home position (P < .05). 3. Average convergence angle in the Random position and the Home position were excessive compared to the ordered angle. There was no statistical difference in the Random position and the Home position (P > .05). 4. Analysis of pearson correlation : In the Random position, the amounts of average thickness of occlusal reduction, the average subgingival margin depth of prepared margin, convergence angle were significantly associated with each other (P < .05). But in the Home position, they were not significantly associated with each other (P < .05). 5. The time needed for preparation in the Home position was faster or equal than that of the Random position as time went on. Conclusion: In conclusion, there were no significant differences between Home position and Random position in measures of occlusal reduction, marginal width, marginal depth, convergence angle. However, preparation time and incidence of damaging adjacent teeth were less in Home position than in Random position. Therefore, if trained properly, Home position which is more ergonomically stable can be adopted for clinical use.

• Journal of rehabilitation welfare engineering & assistive technology
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• v.8 no.4
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• pp.313-318
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• 2014

In this paper, we propose a method for correcting the measurement axis twist that occurs in the process of wearing and each estimation method of joint in which the inertial measurement unit based in health arm by the method of operation upper limb rehabilitation equipment of hemiplegic patients. In order to verify the proposed method, it is fitted with a inertial measurement unit of the upper arm and forearm of the experimenter left arm, verified by comparing actual joint angle is detected by photographing the arbitrary posture, the angle that the estimated joint. Then, it was verified by comparing the applied front / rear techniques for correcting the measurement axis twist. A result of the experiment, before applying the measurement axis twist correction, joint, after but each match rate showed a weak concordance rate in 89.16% and were corrected, measurement axis twist, each concordance rate of joint agreement of 93.28% I understand that it has been 4.12% improvement in the rate.

• Journal of the Korea Society of Computer and Information
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• v.19 no.8
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• pp.119-127
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• 2014

TIn this paper, Hemiplegic patients have gait characteristics different from normal persons. This paper presents a posture measuring and display system reflecting their characteristics. Patients wear 3 sensor modules on thigh, calf and foot. To enhance measuring precision of each sensor module, 3D accelerometer and 3D gyroscope are combined. Gait posture is displayed in 3D by modeling thigh, calf and foot as connected 3D objects based on data of the sensor modules. For convenience in inspecting unusual gait posture of hemiplegic patients, any view angle of the 3D display can be selected. In addition, the current gait phase of RLA(Rancho Los Amigos) gait cycle is determined and displayed in real-time by utilizing the posture information, The phase sequence and duration of each phase can be used in evaluating gait quality of patients.