• Proceedings of the KSRS Conference
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• 2005.10a
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• pp.182-185
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• 2005

Satellite cameras are calibrated before launch in detail and in general, but it cannot be guaranteed that the geometry is not changing during launch and caused by thermal influence of the sun in the orbit. Modem satellite imaging systems are based on CCD-line sensors. Because of the required high sampling rate the length of used CCD-lines is limited. For reaching a sufficient swath width, some CCD-lines are combined to a longer virtual CCD-line. The images generated by the individual CCD-lines do overlap slightly and so they can be shifted in x- and y-direction in relation to a chosen reference image just based on tie points. For the alignment and difference in scale, control points are required. The resulting virtual image has only negligible errors in areas with very large difference in height caused by the difference in the location of the projection centers. Color images can be related to the joint panchromatic scenes just based on tie points. Pan-sharpened images may show only small color shifts in very mountainous areas and for moving objects. The direct sensor orientation has to be calibrated based on control points. Discrepancies in horizontal shift can only be separated from attitude discrepancies with a good three-dimensional control point distribution. For such a calibration a program based on geometric reconstruction of the sensor orientation is required. The approximations by 3D-affine transformation or direct linear transformation (DL n cannot be used. These methods do have also disadvantages for standard sensor orientation. The image orientation by geometric reconstruction can be improved by self calibration with additional parameters for the analysis and compensation of remaining systematic effects for example caused by a not linear CCD-line. The determined sensor geometry can be used for the generation? of rational polynomial coefficients, describing the sensor geometry by relations of polynomials of the ground coordinates X, Y and Z.

• Ocean Systems Engineering
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• v.7 no.3
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• pp.179-193
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• 2017

Dynamic response analysis of offshore triceratops with stiffened buoyant legs under impact and non-impact waves is presented. Triceratops is relatively new-generation complaint platform being explored in the recent past for its suitability in ultra-deep waters. Buoyant legs support the deck through ball joints, which partially isolate the deck by not transferring rotation from legs to the deck. Buoyant legs are interconnected using equally spaced stiffeners, inducing more integral action in dispersing the encountered wave loads. Two typical nonlinear waves under very high sea state are used to simulate impact and non-impact waves. Parameters of JONSWAP spectrum are chosen to produce waves with high vertical and horizontal asymmetries. Impact waves are simulated by steep, front asymmetric waves while non-impact waves are simulated using Stokes nonlinear irregular waves. Based on the numerical analyses presented, it is seen that the platform experiences both steady state (springing) and transient response (ringing) of high amplitudes. Response of the deck shows significant reduction in rotational degrees-of-freedom due to isolation offered by ball joints. Weak-asymmetric waves, resulting in non-impact waves cause steady state response. Beat phenomenon is noticed in almost all degrees-of-freedom but values in sway, roll and yaw are considerably low as angle of incidence is zero degrees. Impact waves cause response in higher frequencies; bursting nature of pitch response is a clear manifestation of the effect of impact waves on buoyant legs. Non-impact waves cause response similar to that of a beating phenomenon in all active degrees-of-freedom, which otherwise would not be present under normal loading. Power spectral density plots show energy content of response for a wide bandwidth of frequencies, indicating an alarming behaviour apart from being highly nonlinear. Heave, being one of the stiff degrees-of-freedom is triggered under non-impact waves, which resulted in tether tension variation under non-impact waves as well. Reduced deck response aids functional requirements of triceratops even under impact and non-impact waves. Stiffened group of buoyant legs enable a monolithic behaviour, enhancing stiffness in vertical plane.

• Korean Journal of Applied Biomechanics
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• v.16 no.4
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• pp.49-59
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• 2006

The purpose of this study was to investigate the relations between the segments of the body, the three dimensional anatomical angle according to sweep shot in ice hockey. The subjects of this study were five professional ice hockey players. The reflective makers were attached on anatomical boundary line of body. For the movement analysis three dimensional cinematographical method(APAS) was used and for the calculation of the kinematic variables a self developed program was used with the LabVIEW 6.1 graphical programming(Johnson, 1999) program. By using Eular's equations the three dimensional anatomical Cardan angles of the joint and ice hockey stick were defined. 1. In three dimensional linear velocity of blade the Y axis showed maximum linear velocity almost impact, the X axis(horizontal direction) and the Z axis(vertical direction) maximum linear velocity of blade did not show at impact but after impact this will resulted influence upon hitting puck. 2. The resultant linear velocity of each segment of right arm showed maximum resultant linear velocity at impact. It could be suggest that the right arm swing patterns is kind of push-like movement. therefore the upper arm is the most important role in the right arm swing. 3. The three dimensional anatomical angular displacement of trunk in flexion-extension showed flexion all around the wrist shot. The angular displacement of trunk in internal-external rotation showed internal rotation angle at the backswing top and and increased the angle after the impact. while there is no significant adduction-abduction. 4. The three dimensional anatomical angular displacement of trunk showed most important role in wrist shot. and is follwed by shoulder joints, in addition the movement of elbow/wrist joints showed least to the shot. this study result showed upperlimb of left is more important role than upperlimb of right.

• 제어로봇시스템학회:학술대회논문집
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• 2005.06a
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• pp.296-301
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• 2005

This paper describes the kinematics, dynamics and control of a 6-DOF shaking table with a bell crank structure, which converts the direction of reciprocating movements. In this shaking table, the bell crank mechanism is used to reduce the amount of space needed to install the shaking table and create horizontal displacement of the platform. In kinematics, joint design is performed using $Gr{\ddot{u}}bler's$ formula. The inverse kinematics of the shaking table is discussed. The derivation of the Jacobian matrix is presented to evaluate singularity conditions. Considering the maximum stroke of the hydraulic actuator, collision between links and singularity, workspace is computed. In dynamics, computations are based on the Newton-Euler formulation. To derive parallel algorithms, each of the contact forces is decomposed into one acting in the direction of the leg and the other acting in the plane orthogonal to the direction of the leg. Applying the Newton-Euler approach, the solution of inverse dynamics is almost completely parallel. Only one of the steps-the application of the Newton-Euler equations to the platform-must be performed on one single processor. Finally, the efficient control scheme is proposed for the tracking control of the motion platform.

• Journal of the Korean Society of Propulsion Engineers
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• v.1 no.2
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• pp.12-21
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• 1997

Nowadays, non-pollution energy sources have been strongly needed because of the exhaustion of fossil fuels and serious environmental problems. Because wind energy can be enormously obtained from natural atmosphere, this type of energy has lots of advantages in a economic and pollution point of view. This study has established the aerodynamic and structural design procedure of the rotor blade with an appropriate aerodynamic performance and structural strength for the 500㎾ medium class wind turbine system. The aerodynamic configuration of the rotor blade was determined by considering the wind condition in the typical local operation region, and based on this configuration aerodynamic performance analysis was performed. The rotor blade has the shell-spar structure based on glass/epoxy composite material and is composed of shank including metal joint parts and blade. Structural design was done by the developed design program in this study and structural analysis, for instance stress analysis, mode analysis and fatigue life estimation, was performed by the finite element method. As a result, a medium scale wind turbine rotor blade with starting characteristics of 4m/s wind speed, rated power of 500㎾ at 12m/s wind speed and over 20 years fatigue life has been designed.

• Journal of the Korean Institute of Telematics and Electronics
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• v.25 no.10
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• pp.1173-1182
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• 1988

The stability, energetic efficiency and walking volume are affected by the geometric structure of legs of a walking robot. A quadruped walking robot is considered to have large stability margin among the walking robots and pantograph leg permits large walk stroke and mutually independent vertical and horizontal movements, but the kinematic characteristics are difficult to analyze. Graphical method may be useful to characterize three dimensional legged motion of the pantograph mechanism. We present the modelling method for three different quadruped robots with pantograph legs that have different joints mechanism. The modeled robots are animated by a path that is planned with respect to the center of body. In particular, graphical animation incorporates leg control to rotation and side walking and uses the window of Sun-3 system for displaying joint information.

• The korean journal of orthodontics
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• v.22 no.1
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• pp.205-227
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• 1992

This study was aimed to investigate the characteristics & the causative areas of the adult skeletal class III malocclusions with different facial divergency. The lateral cephalograms of 80 subjects with skeletal class III malocclusion from 17 to 29 years of age were classified into 3 groups according to SN-MP angle; hypodivergent group $(21.65{\pm}3.52^{\circ})$, neutrodivergent group $(30.50{\pm}2.29^{\circ})$ and hyperdivergent group $(40.02{\pm}3.98^{\circ})$. The data were gathered by digitizing of the traced cephalograms and were statistically analyzed. The results were as follows: 1. The anterior cranial base of the hyperdivergent group was shortest & tipped upwardly to the FH plane. 2. The maxilla of hyperdivergent group was shortest anteroposteriorly and positioned posteriorly to the anterior cranial base. 3. The degree of the mandibular prognathism in hyperdivergent group was less than the hypodivergent group. The hyperdivergent group showed the downward & backward rotated mandible. 4. The mandibular ramus & body was short & slender in the hyperdivergent group and the gonial angle was greatest in the hyperdivergent group. 5. The temporomandibular joint was positioned more superiorly to the anterior cranial base in the hyperdivergent group. 6. The cranial base, palatal plane, occlusal plane and mandibular plane were diverged in the hyperdivergent group. And this group had a great anterior total facial height, especially anterior lower facial height. 7. The craniofacial characteristics of skeletal class III malocclusion were critical in the vertical structure than the horizontal.

• The Journal of Korean Academy of Orthopedic Manual Physical Therapy
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• v.14 no.2
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• pp.25-33
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• 2008

Purpose : This study was investigated the effect on grasp and pinch strength according to degree of flexion in elbow joint. Methods : Thirty male and thirty female students, aged 20 to 31 years were tested for using opened positioning with their shoulder abduction at $55^{\circ}$ and shoulder horizontal adduction at $30^{\circ}$ in four elbow flexion($0^{\circ}$, $45^{\circ}$, $90^{\circ}$, $135^{\circ}$). An electronic dynamometer(E-LINK V900s Evaluation System)and goniometer were used to measure grasp and pinch strength. Results : The average grasp strength of the dominant hand was strongest at elbow $45^{\circ}$ however, weakest at elbow $135^{\circ}$ flexion in both of male and female. The average pinch strength of the dominant hand was strongest at elbow $135^{\circ}$ flexion in both of male and female. The average pinch strength of dominant hand was weakest at elbow $45^{\circ}$ flexion in both of male and female. According to degree of elbow flexion in both of male and female, grasp and pinch strength was no significant statistically. In analyzing correlations, the grasp strength of male showed the most significant difference at elbow $45^{\circ}$ & $90^{\circ}$ flexion, and the pinch strength was most significant difference at elbow $0^{\circ}$ & $45^{\circ}$ flexion. Conclusion : In analyzing correlations, the grasp strength of female showed the most significant difference at elbow $90^{\circ}$ & $135^{\circ}$ flexion, and the pinch strength was most significant difference at elbow $45^{\circ}$ & $90^{\circ}$ flexion.

• Journal of Preventive Medicine and Public Health
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• v.30 no.4 s.59
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• pp.805-814
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• 1997

Injuries to the menisci occur in a variety of ways, most commonly with a twist, pivot, squat, or valgus stress to the knee. Tear patterns are classified to longitudinal, horizontal, or transverse features according to the mechanism of injury. Work-related meniscal tear usually occurs with a repetitive usage of the foot, hence it can be classified as a cumulative traumatic disorder. We found a 47 year-old female worker who had been taking charge of repetitive foot-switch stepping for 8 years. She suffered from pain in the right knee since 5 months ago. Tenderness along the medial joint line of the right knee was observed and pain was aggravated with full flexion of the right knee. On magnetic resonance imaging, high signal intensity was observed at the posterior horn of the medial meniscus of the right knee. Degenerative longitudinal and transverse complex tear in the medial meniscus was observed on arthroscopy. Arthroscopic partial meniscectomy was performed. We surveyed the work process and the health status of co-workers. It turned out that the work process was compatible to injure the meniscus and nine out of fourteen co-worker(64.3%) complained pain of the knee. No other factors related to her meniscal tear could be found except for the situation at her work. Therefore, we conclude that meniscal tear is related to the repetitive stepping of foot switch.

• Korean Journal of Applied Biomechanics
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• v.26 no.1
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• pp.71-82
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• 2016

Objective: The purpose of this study was to investigate kinematic comparisons of Tsukahara vault in gymnastics between a top-level athlete and sublevel collegiate athletes in order to obtain information on key biomechanical points for successful Tsukahara vaults. Methods: An Olympic gold medalist (height, 160 cm; weight, 52 kg; age, 25 years) and five sublevel collegiate gymnasts (height, $168.2{\pm}3.4cm$; weight, $59.6{\pm}3.1kg$; age, $23.2{\pm}1.6years$) participated in this study. They repeatedly performed Tsukahara vaults including one somersault. Fourteen motion-capturing cameras were used to collect the trajectories of 26 body markers during Tsukahara vaults. Event time, displacement and velocity of the center of mass, joint angles, the distance between the two hands on the horse, and averaged horizontal and vertical impact forces were calculated and compared. Results: The top-level athlete showed a larger range of motion (ROM) of the hip and knee joints compared to sublevel collegiate athletes during board contact. During horse contact, the top-level athlete had a narrow distance between the two hands with extended elbows and shoulders in order to produce a strong blocking force from the horse with a shorter contact time. At the moment of horse take-off, reactive hip extension of the top-level athlete enhanced propulsive take-off velocity and hip posture during post-flight phase. Conclusion: Even though a high velocity of the center of mass is important, the posture and interactive action during horse contact is crucial to post-flight performance and the advanced performance of Tsukahara vaults.