• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• v.1
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• pp.115-120
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• 2006

This article propose a new idea of developing a hybrid scheme to achieve faster INS alignment with higher accuracy using a novel procedure to estimate the initial attitude angles that combines a Kalman filter and Adaptive Neuro-Fuzzy Inference System architecture. A tactical grade inertial measurement unit was applied to verify the performance of proposed scheme in this study. The preliminary results indicated the outstanding improvements in both time consumption for fine alignment process and accuracy of estimated attitude angles, especially in heading angles. In general, the improvement in terms of time consumption and the accuracy of estimated attitude estimated accuracy reached 80% and 70% respectively during alignment process after compensating the attitude angles estimated by an extended Kalman filter with 15 states using proposed approach. It is worth mentioned that the proposed approach can be implemented in general real time navigation applications.

• Journal of the Ergonomics Society of Korea
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• v.25 no.2
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• pp.51-62
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• 2006

In assessing risks related to working posture, pictures of postures are taken from various directions, which can be a source of observation error. Joint postures of the neck, lower back, knee, shoulder, and elbow were taken from 7 different viewing angles and 19 observers estimated joint angles by observing the pictures in 2-dimensional display. The joint angles were also measured using an optoelectronic motion measurement system. The estimation error increased as the viewing angle varies from the right side of the human body, but the patterns differ according to which joint angles were being observed. Guidelines to increase the validity of observation of joint angles were presented based on the results. In general, it is recommended to maintain the viewing angle within 20 degrees from the right side of the human body, while different ranges of viewing angle are recommended for each joint angle.

• The Journal of Korea Robotics Society
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• v.15 no.2
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• pp.131-138
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• 2020

This paper proposes a low-cost robotic surgery system composed of a general purpose robotic arm, an interface for daVinci surgical robot tools and a modular haptic controller utilizing smart actuators. The 7 degree of freedom (DOF) haptic controller is suspended in the air using the gravity compensation, and the 3D position and orientation of the controller endpoint is calculated from the joint readings and the forward kinematics of the haptic controller. Then the joint angles for a general purpose robotic arm is calculated using the analytic inverse kinematics so that that the tooltip reaches the target position through a small incision. Finally, the surgical tool wrist joints angles are calculated to make the tooltip correctly face the desired orientation. The suggested system is implemented and validated using the physical UR5e robotic arm.

• Communications of Mathematical Education
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• v.22 no.3
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• pp.289-310
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• 2008

The purpose of study is to propose the possibilities of finding trigonometric function values using trigonometric function graphs instead of the unit circle method. And it is to discuss how to enhance relating trigonometric function value finding to graphs construction, and students conceptual understanding of the properties of trigonometric functions. The conclusions of this study are the effectiveness of function value finding using trigonometric function graphs, the use of a precise term of function value finding given general angles, consideration of a link between function value finding and graphs, and the possibility of teaching trigonometric function graphs in advance of function value finding.

• The Journal of Korean Physical Therapy
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• v.25 no.6
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• pp.379-385
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• 2013

Purpose: The purpose of this study is to compare kinematics on lower limbs between stair walking with high heel and barefoot in healthy adult women. Methods: 18 healthy adult women were recruited in this study. The subjects performed stair ascent and descent with high heels and barefoot. The experiment was conducted in random order and repeated three times for each stair walking with high heels and barefoot. The movements of lower limb joints were measured and analyzed using a three-dimensional analysis system. Results: The ankle, knee, and hip flexion angles on the sagittal plane exhibited statistically significant differences between stair ascent and descent with high heels and barefoot. The pelvic forward tilt angles showed statistically significant differences only during stair ascent. The ankle inversion, hip abduction and pelvic lateral tilt angles on the frontal plane showed statistically significant differences between stair walking with high heels and barefoot. On the transverse plane, the hip rotation angles showed statistically significant differences between the high-heeled and barefoot gait during stair ascent and descent. However, the pelvic rotation angles showed no statistically significant differences. Conclusion: Therefore, wearing high-heeled shoes during stair walking in daily life is considered to influence lower limb kinematics due to the high heel, and thus poses the risks of pain, and low stability and joint damage caused by changes in the movement of lower limb joints.

• Journal of the Korean Society of Physical Medicine
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• v.5 no.1
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• pp.1-6
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• 2010

Purpose : This research intended to find out the effects of scalenus medius muscle relaxed posture on the increase of head-neck rotation for general adults. Methods : This research was conducted on 30 subjects whose both sides head neck rotation angles are not the same and that agreed to participate in the experiment. In a posture of sitting erectly on a mat, both sides head neck rotation angles were measured with C-ROM equipment, and while supporting arm in direction opposite the side where head neck rotation limited and leaning over the body at 45 degree and neck at vertical condition against ground, head-neck rotation angles were measured each with C-ROM equipment. Results : The Head-Neck rotation angle on the side of limited head-neck rotation demonstrated more increase in scalenus medius relaxed posture than in erect sitting posture, showing significant difference statistically(p<0.05). The head-neck rotation angle on the side of non-limited Head-Neck rotation demonstrated more decrease in scalenus medius relaxed posture than in erect sitting posture, not showing any significant difference statistically (p>0.05). Conclusions : This posture may be used for preventing limit of head-neck rotation caused of scalenus medius muscle tension and increasing head-neck rotation.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.17 no.4
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• pp.379-386
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• 1992

In this paper a direction finding method which can which can estimate the direction angles of source signals impinging on the sensor array in which sensor noises are correlated is studied. This method performs the estimation of source direction angles form sensors, regardless of sensor noise correlation, by eliminating the sensor noise correlation coefficient which can be accurately estimated. Finally, this paper shows, through the computer simulation, that the proposed, method is extremely useful and superior when there exists the noise correlation between sensors, .

• Journal of Korean Foot and Ankle Society
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• v.9 no.2
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• pp.146-150
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• 2005

Purpose: We made a radiological comparison between $60^{\circ}$ distal Chevron osteotomy with short armed two parts and $40^{\circ}$ distal Chevron osteotomy with long armed one part performing operation in cases of hallux valgus angle of less than $40^{\circ}$, intermetatarsal angle of less than $15^{\circ}$. Materials and Methods: 12 cases with $60^{\circ}$ distal Chevron osteotomy and 12 cases with $40^{\circ}$ distal Chevron osteotomy were selected from October 2000 to March 2005. We have analysed the hallux valgus angle, 1-2 intermetatarsal angle, metatarsal length, distal metartarsal articular angle and angulation at osteotomy site on lateral view in each radiological films taken at preoperative, postoperative and 3 months after operation presuming bone union. All cases were women, both sides were 9 cases and average age was 52.3 years old. Results: Data taken at preoperative, postoperative and 3 months follow up films in $60^{\circ}$ distal Chevron osteotomy were as follows; the hallux valgus angles were $32.1^{\circ}$, $10.9^{\circ}$, $13.8^{\circ}$, the 1-2 intermetatarsal angles were $13.6^{\circ}$, $8.5^{\circ}$, $8.4^{\circ}$, the metatarsal length were 60.6 mm, 58.8 mm, 58 mm, the distal metartarsal articular angles were $13^{\circ}$, $6^{\circ}$, $6.6^{\circ}$ and 3 cases were over $3^{\circ}$ angulation at lateral view. In $40^{\circ}$ distal Chevron osteotomy, the hallux valgus angles were $34.5^{\circ}$, $11.6^{\circ}$, $15.3^{\circ}$, the 1-2 intermetatarsal angles were $12.7^{\circ}$, $8.2^{\circ}$, $7.8^{\circ}$, the metatarsal length were 59.2 mm, 56.9 mm, 55.9 mm, the distal metartarsal articular angles were $12^{\circ}$, $7.3^{\circ}$, $7.3^{\circ}$ and there were no case with angulation over $3^{\circ}$ at lateral view. Conclusion: In comparison between $60^{\circ}$ distal Chevron osteotomy and $40^{\circ}$ distal Chevron osteotomy measuring at postoperative and follow up, most of all data were similar, but 3 cases over $3^{\circ}$ angulation at lateral view happened in $60^{\circ}$ Chevron osteotomy. This result showed that $40^{\circ}$ distal Chevron osteotomy fixing with screws through long armed one part may have benefit than $60^{\circ}$ distal Chevron osteotomy fixing with K-wires through short armed two parts in making rigid fixation, even though there is a personal difference of technigue.

• Journal of Mechanical Science and Technology
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• v.19 no.8
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• pp.1632-1648
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• 2005

The effects of Reynolds number on the non-nulling calibration of a typical cone-type five-hole probe have been investigated for the representative Reynolds numbers in turbomachinery. The pitch and yaw angles are changed from - 35 degrees to 35 degrees with an angle interval of 5 degrees at six probe Reynolds numbers in range between $6.60{\times}10^3\;and\;3.17{\times}10^4$. The result shows that not only each calibration coefficient itself but also its Reynolds number dependency is affected significantly by the pitch and yaw angles. The Reynolds-number effects on the pitch- and yaw-angle coefficients are noticeable when the absolute values of the pitch and yaw angles are smaller than 20 degrees. The static-pressure coefficient is sensitive to the Reynolds number nearly all over the pitch- and yaw-angle range. The Reynolds-number effect on the total-pressure coefficient is found remarkable when the absolute values of the pitch and yaw angles are larger than 20 degrees. Through a typical non-nulling reduction procedure, actual reduced values of the pitch and yaw angles, static and total pressures, and velocity magnitude at each Reynolds number are obtained by employing the calibration coefficients at the highest Reynolds number ($Re=3.17{\times}10^4$) as input reference calibration data. As a result, it is found that each reduced value has its own unique trend depending on the pitch and yaw angles. Its general tendency is related closely to the variation of the corresponding calibration coefficient with the Reynolds number. Among the reduced values, the reduced total pressure suffers the most considerable deviation from the measured one and its dependency upon the pitch and yaw angles is most noticeable. In this study, the root-mean-square data as well as the upper and lower bounds of the reduced values are reported as a function of the Reynolds number. These data would be very useful in the estimation of the Reynolds-number effects on the non-nulling calibration.

• 유체기계공업학회:학술대회논문집
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• 2000.12a
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• pp.193-199
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• 2000

The effects of Reynolds number on the non-nulling calibration of a cone-type five-hole probe in low-speed flows have been investigated at the Reynolds numbers of $2.04{\times}10^3,\;4.09{\times}10^3$, and $6.13{\times}10^3$. The calibration is conducted at the pitch and yaw angles in ranges between -35 degrees and 35 degrees with an angle interval of 5 degrees. The result shows that each calibration coefficient, in general, is a function of the pitch and yaw angles, so that the pre-existing calibration data in a nulling mode are not enough in accounting for the full non-nulling calibration characteristics. Due to the interference of the probe stem, the calibration coefficients have more Reynolds number sensitivity at positive pitch angles than at negative ones.