• The Journal of Korean Society for Radiation Therapy
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• v.26 no.1
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• pp.37-42
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• 2014

Purpose : At the time of the pelvis cancer radiation treatment using the belly board, set-up error is large because of a prone position. In order to improve the reproducibility, we made Vac-lock type belly board. In this study, we attempt to validate its utility. Materials and Methods : We compared belly board and Vac-lock type belly board through the OBI. OBI was performed three times with entire course of treatment and the setup errors in the direction of X axis, Y axis, Z axis were recorded and calculated the distance from the isocenter. Results : X axis, Y axis, Z axis setup errors with existing belly board were 0.32 cm, 0.41 cm, 0.29 cm. The setup errors with the vac-lock type belly board were 0.12 cm, 0.19 cm, 0.17 cm. Further, errors of 0~0.29 cm were increased from 48% to 83% when using VLT belly board. Error of 0.5 cm or more was reduced from 21% to 2%. Conclusion : Vac-lock type belly board is able to maintain the efficacy of existing and create to match the characteristics of the patient. Therefore We think that vac-lock type belly board is very useful in pelvic cancer patients.

• Spatial Information Research
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• v.20 no.3
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• pp.27-38
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• 2012

As the necessity of forest conservation and management has been increased, various forest studies using LIDAR data have been actively performed. These studies often utilize the tree height as an important parameter to measure the forest quantitatively. This study thus attempt to apply two representative methods to estimate tree height from airborne LIDAR data and compare the results. The first method based on the detection of the individual trees using a local maximum filter estimates the number of trees, the position and heights of the individual trees, and the mean tree height. The other method estimates the maximum and mean tree height, and the crown mean height for each grid cell or the entire area from the canopy height model (CHM) and height histogram. In comparison with the field measurements, 76.6% of the individual trees are detected correctly; and the estimated heights of all trees and only conifer trees show the RMSE of 1.91m and 0.75m, respectively. The tree mean heights estimated from CHM retain about 1~2m RMSE, and the histogram method underestimates the tree mean height with about 0.6m. For more accurate derivation of diverse forest information, we should select and integrate the complimentary methods appropriate to the tree types and estimation parameters.

• Journal of the Microelectronics and Packaging Society
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• v.27 no.2
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• pp.33-38
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• 2020

In the photoelectrochemical (PEC) water splitting, GaN is one of the most promising photoanode materials due to high stability in electrolytes and adjustable energy band position. However, the application of GaN is limited because of low efficiency. To improve solar to hydrogen conversion efficiency, we introduce a Cobalt Phosphate (Co-pi) catalyst by photo-electrodeposition. The Co-pi deposition GaN were characterized by SEM, EDS, and XPS, respectively, which illustrated that Co-pi was successfully decorated on the surface of GaN. PEC measurement showed that photocurrent density of GaN was 0.5 mA/㎠ and that of Co-pi deposited GaN was 0.75 mA/㎠. Impedance and Mott-Schottky measurements were performed, and as a result of the measurement, polarization resistance (R_p) and increased donor concentration (N_D) values decreased from 50.35 Ω to 34.16 Ω were confirmed. As a result of analyzing the surface components before and after the water decomposition, it was confirmed that the Co-pi catalyst is stable because Co-pi remains even after the water decomposition. Through this, it was confirmed that Co-pi is effective as a catalyst for improving GaN efficiency, and when applied as a catalyst to other photoelectrodes, it is considered that the efficiency of the PEC system can be improved.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.20 no.4
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• pp.143-148
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• 2020

In the case of a system that detects and controls the phase of an alternating voltage, the analog control method compensates the phase offset part by filtering for the detected phase and applies it to the control. However, in the digital control method, precise control cannot be achieved due to an error between the operating frequency of the microprocessor or the microcontroller and the input phase time when controlled using such phase detection. In general, when the method used is a certain time, the accumulated error is compensated and adjusted at random. To solve this problem, a method of detecting a zero point in real time and compensating for the operating frequency of the microprocessor is needed. Therefore, the research to be performed in this paper to reduce these errors and apply them to precise digital control is as follows. 1) Research on how to implement Zero Crossing Detection algorithm through simulation modeling to compensate the zero point to match the operating frequency through detection. 2) A study on the method of detecting zero points in real time through the Zero Crossing Detection design using a microcontroller and compensating for the operating frequency of the microprocessor. 3) A study on the estimation of the rotor position of BLDC motors using the Zero Crossing Detection circuit.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.27 no.3
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• pp.130-134
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• 2017

In this study, numerical simulation was performed to focus on optimized process condition for obtaining a long-term growth and high quality SiC crystal. It could be optimized by considering the change of fluid and a carbon flow in the Si melt added with 40 % Cr. The Crystal Growth Simulator ($CGSim^{TM}$, STR Group Ltd.) was used as a numerical simulation. It was confirmed that many parameters such as temperature, rotation speed of seed crystal and crucible, and seed position during the crystal growth step had a strong influence on the speed and direction of solution flow for uniform temperature gradient and stable crystal growth. The optimized process condition for the solution growth of SiC crystal was successfully exhibited by adjusting various process parameters in the numerical simulation, which would be helpful for real crystal growth.

• Journal of the Institute of Electronics Engineers of Korea CI
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• v.41 no.3
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• pp.27-36
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• 2004

Detection and recognition of human faces in images can be considered as an important aspect for applications that involve interaction between human and computer. In this paper, we propose a face recognition method using eigenfaces and fuzzy neural networks. The Principal Components Analysis (PCA) is one of the most successful technique that have been used to recognize faces in images. In this technique the eigenvectors (eigenfaces) and eigenvalues of an image is extracted from a covariance matrix which is constructed form image database. Face recognition is Performed by projecting an unknown image into the subspace spanned by the eigenfaces and by comparing its position in the face space with the positions of known indivisuals. Based on this technique, we propose a new algorithm for face recognition consisting of 5 steps including preprocessing, eigenfaces generation, design of fuzzy membership function, training of neural network, and recognition. First, each face image in the face database is preprocessed and eigenfaces are created. Fuzzy membership degrees are assigned to 135 eigenface weights, and these membership degrees are then inputted to a neural network to be trained. After training, the output value of the neural network is intupreted as the degree of face closeness to each face in the training database.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.44 no.3
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• pp.64-69
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• 2007

Motion control of the system is a position control of motor. Motion control of an uncertain robot system is considered as one of the most important and fundamental research directions in the robotics. Some distinguished works using linear control, adaptive control, robust control strategies based on computed torque methodology have been reported. However, it is generally recognized within the control community that these strategies suffer from the following problems : the exact robot dynamics are needed and hard to implement, the adaptive control cannot guarantee the performance during the transient period for adaptation under the variation, the robust control algorithms such as the sliding mode control need information on the bounds of the possible uncertainty and disturbance. And it produces a large control input as well. In this dissertation, a motion control for the unmanned intelligent robot system using disturbance observer is studied. This system is affected with an impact vibration disturbance. This paper describes a stable motion control of the system with the consideration of external disturbance. To obtain the stable motion independently against the external disturbance, the disturbance rejection is strongly required. To address the above issue, this paper presents a Disturbance OBserver(DOB) control algorithm. The validity of the suggested DOB robust control scheme is confirmed by several computer simulation results. And the experiments with a motor system is performed to give the validity of applicability in the industrial field. This results make the easier implementation of the controller possible in the field.

• Physical Therapy Korea
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• v.14 no.2
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• pp.44-52
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• 2007

This study was carried out to compare the muscle activities of the shoulder stabilizers between persons with and without winging scapular during push-up plus exercise (adds the scapular protraction to the general push-up exercise). For this study, eleven males with winging scapular and eleven healthy males were recruited. Surface electromyographic (EMG) activity was recorded from the serratus anterior, upper trapezius, lower trapezius, infraspinatus, and pectoralis major while the subjects performed the push-up plus. Each push-up plus was subdivided into three phases according to the elbow position which was measured using the 3-D motion analysis system: elbow flexion (EF), elbow extension (EE), and shoulder protraction phases (SP). Two-way repeated measure ANOVA (phase ${\times}$ group) were used for statistical analysis. There was significant phase by group interaction only on the EMG composition ratio of the serratus anterior (p>.05). The EMG composition ratio of the serratus anterior was significantly higher in SP than in either EF or EE however, it was not different between winging scapular and normal groups. For both groups, the EMG composition ratio of upper trapezius, lower trapezius, and pectoralis major was significantly different across the phases of push-up plus, but the infraspinatus EMG composition ratio was not. For both groups, in EF and EE phases, the EMG composition ratio of both pectoralis major and serratus anterior were relatively higher than that of other muscles. However, in both groups, the EMG composition ratio of the serratus anterior became much more predominant than that of the pectoralis major. In addition, infraspinatus activated greater than pectoralis major. These results showed that the push-up plus exercise is effective to selectively strengthen the serratus anterior for both individuals with and without winging scapular, but not equally effective for other shoulder stabilizers.

• Physical Therapy Korea
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• v.24 no.2
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• pp.1-8
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• 2017

Background: Individuals with spinal cord injury (SCI) rely on their upper limbs for body-lifting activity (BLA). While studies have examined the electromyography (EMG) and kinematics of the shoulder joints during BLA, no studies have considered foot position during BLA. Objects: This study compared the effects of different foot positions during BLA on the shoulder muscle activities, peak plantar pressure, knee flexion angle, and rating perceived exertion in individuals with SCI. Methods: The study enrolled 13 mens with motor-complete paraplegic SCI, ASIA (American Spinal Injury Association) A or B. All subjects performed BLA with the feet positioned on the wheelchair footrest and on the floor independently. Surface EMG was used to collect data from the latissimus dorsi, pectoralis major, serratus anterior, and triceps brachii. The peak plantar pressure was measured using pedar-X and the knee flexion angle with Image J. Borg's rating perceived exertion scale was used to measure the physical activity intensity level. The paired t-test was used to compare the shoulder muscle activities, peak plantar pressure, knee flexion angle, and rating perceived exertion between the two feet positions during BLA. Results: The activity of the latissimus dorsi, pectoralis major, serratus anterior, and triceps brachii and rating perceived exertion decreased significantly and the peak plantar pressure and knee flexion angle increased significantly when performing BLA with the feet positioned on the wheelchair footrest compared with on the floor (p<.05). Conclusion: These findings suggest that individuals with SCI may perform BLA with the feet positioned on the wheelchair footrest for weight-relief lifting to decrease the shoulder muscle activities and the rating perceived exertion and to increase the peak plantar pressure and the knee flexion angle.

• Physical Therapy Korea
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• v.27 no.1
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• pp.1-10
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• 2020

Background: Thoracic spine self-mobilization exercise is commonly used to manage patients with neck pain. However, no previous studies have investigated the effects of thoracic spine self-mobilization exercise alone in patients with chronic neck pain. Objects: The purpose of this study was to investigate the effects of thoracic self-mobilization using a tool on cervical range of motion (ROM), disability level, upper body posture, pain and fear-avoidance beliefs questionnaire (FABQ) in patients with chronic neck pain. Methods: The subjects were 49 patients (21 males, 28 females) with chronic neck pain. The subjects were randomly divided into an experimental group (EG, n = 23) and control group (CG, n = 26). For the EG, thoracic self-mobilization was applied. We placed a tool (made with 2 tennis balls) under 3 different vertebral levels (T1-4, T5-8, T9-12) of the thoracic spine and the subjects performed crunches, which included thoracic flexion and extension in supine position. Five times × 3 sets for each levels, twice a week, for 4 weeks. Cervical pain, disability, upper body posture, FABQ results, and ROM were evaluated at baseline, after 4 weeks of intervention, and at 8 weeks of follow-up. Assessments included the quadruple visual analogue scale (QVAS); Northwick Park neck pain questionnaire (NPQ); craniovertebral angles (CVA), forward shoulder angle (FSA) and kyphosis angle (KA) measurements for upper body posture; FABQ and cervical ROM testing. Results: The EG showed a statistically significant improvement after intervention in the QVAS (-51.16%); NPQ (-53.46%); flexion (20.95%), extension (25.32%), left rotation (14.04%), and right rotation (25.32%) in the ROM of the cervical joint; KA (-7.14%); CVA (9.82%); and FSA (-4.12%). Conclusion: These results suggest that, for patients with chronic neck pain, thoracic self-mobilization exercise using a tool (tennis balls) is effective to improve neck pain, disability level, the ROM, and upper body posture.