• 한국운동역학회지
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• 제27권2호
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• pp.91-97
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• 2017

Objective: To investigate rotation movement of segment for performing each position and its effect on knee/hip angulation, COM inclination, and edging angle changes. Method: Twelve Alpine skiers (age: $25.8{\pm}4.8years$, height: $173.8{\pm}5.9cm$, weight: $71.4{\pm}7.4kg$, length of career: $9.9{\pm}4.6years$) participated in this study. Each skier was asked to perform counter-rotation, neutral, and rotation positions. Results: Shank and thigh were less rotated in the counter-rotation position than in other positions, whereas the trunk and pelvis were more counter-rotated (p<.05). Hip angulation, COM inclination, and edging angle were significantly greater in the counter-rotation position than in other positions (p<.05). Conclusion: Our finding proved that the counter-rotation position increases hip angulation, COM inclination, and edging angle. Consequently, we suggest that skiers should perform counter-rotation of the trunk and pelvis relative to the ski direction in the vertical axis for the counter-rotation position. Further analysis will continue to investigate the effects of the counter-rotation position in real ski slope with kinetic analysis.

• 한국재료학회지
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• 제33권2호
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• pp.54-62
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• 2023

The most comprehensive and particularly reliable method for non-destructively measuring the residual stress of the surface layer of metals is the sin²ψ method. When X-rays were used the relationship of ε_φψ-sin²ψ measured on the surface layer of the processing metal did not show linearity when the sin²ψ method was used. In this case, since the effective penetration depth changes according to the changing direction of the incident X-ray, σ_φ becomes a sin²ψ function. Since σ_φ cannot be used as a constant, the relationship in ε_φψ-sin²ψ cannot be linear. Therefore, in this paper, the orthogonal function method according to Warren's diffraction theory and the basic profile of normal distribution were synthesized, and the X-ray diffraction profile was calculated and reviewed when there was a linear strain (stress) gradient on the surface. When there is a strain gradient, the X-ray diffraction profile becomes asymmetric, and as a result, the peak position, the position of half-maximum, and the centroid position show different values. The difference between the peak position and the centroid position appeared more clearly as the strain (stress) gradient became larger, and the basic profile width was smaller. The weighted average strain enables stress analysis when there is a strain (stress) gradient, based on the strain value corresponding to the centroid position of the diffracted X-rays. At the 1/5 I_max max height of X-ray diffraction, the position where the diffracted X-ray is divided into two by drawing a straight line parallel to the background, corresponds approximately to the centroid position.

• International Journal of Advanced Culture Technology
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• 제12권2호
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• pp.368-374
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• 2024

During an X-ray examination, the beam of radiation is dispersed in many directions. We believe that managing radiation dose is about providing transparency to users and patients in the accurate investigation and analysis of radiation dose. The purpose of measuring the radiation dose as a function of location is to ensure that medical personnel using the equipment or participating in the operating room are minimally harmed by the different radiation doses depending on their location. Four mobile diagnostic X-ray units were used to analyze the radiation dose depending on the spatial location. The image intensifier and the flat panel detector type that receives the image analyzed the dose by angle to measure the distribution of the exposure dose by location. The radiation equipment used was composed of four units, and measuring devices were installed according to the location. The X-ray (C-arm) was measured by varying the position from 0 to 360 degrees, and the highest dose was measured at the center position based on the abdominal position, and the highest dose was measured at the 90° position for the head position when using the image intensifier equipment. The operator or medical staff can see that the radiation dose varies depending on the position of the diagnostic radiation generator. In the image intensifier and flat panel detector type that accepts images, the dose by angle was analyzed for the distribution of exposed dose by position, and the measurement method should be changed according to the provision of dose information that is different from the dose output from the equipment according to the position.

• 복식문화연구
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• 제12권5호
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• pp.757-768
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• 2004

This study was aimed to provide the fundamental and various measurement data of the head and face for Korean children. Two hundred sixty nine female children, aged nine to twelve years, participated for this study. The 28 regions on the head and face of the subjects were directly measured by the expert experimenters. Factor analysis, cluster analysis, GLM analysis and Tukey HSD test were performed' using these data. Through factor analysis, six factors were extracted upon factor scores and those factors comprised 71.42% for the total variances. Four clusters as their head and face shape were categorized using six factor scores by cluster analysis. Type 1 was characterized by the shorter head & face length and width and the lowest position from forehead to nose. Type 2 had the longer head & face length and width and the highest ear position and the largest mouse width. Type 3 was characterized by the longest and head & face type and the widest head & face girth. Type 4 was characterized by shortest head & face length the lower ear and lips position.

• 동의생리병리학회지
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• 제22권4호
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• pp.918-929
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• 2008

This study investigated the effects of inverted position on EEG and heart rate variability before and after Bang song gong. BSG is a training method using in qi-gong and meditation to give a convergence of consciousness on body segments in order and take a silent speech of 'song'. The subjects were the 14 university students(n=7 per group) who had not experienced any medical problem and had not practiced BSG. They took a practice of the two way of BSG training program for 30 minutes every other day for two weeks. During practicing BSG, A group took sitting position and lean sitting position by turns, B group took inverted and lean sitting position in the same way. Statistical analysis conducted by two-way ANOVA($2groups^{\ast}2periods$) with p<0.05 for average difference of EEG and HR according to position change in each group before and after BSG. In A group, EEG and HR were changeless irrespective of the change of position and BSG. On the other hand, in B group, significant changes were observed in EEG(p<0.05). ${\alpha}$ wave of inverted position were on the increase, ${\beta}$ and ${\delta}$ wave of inverted position showed smaller power after two weeks training. In the variation of HR, there were smaller variation according to the position change after BSG compared to before BSG(p<0.05). The results suggested that an inverted position may make the depth of meditation deeper, and is likely to be effective for decreasing tension of brain and the sleepiness during qi-gong training. In addition to, an inverted position seemed to promote control of blood pressure of brain. So the application of an inverted position to 'BSG' will be very helpful to achieve deeper relaxation and to obtain the desired effect from qi-gong training.

• 한국운동역학회지
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• 제16권1호
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• pp.151-158
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• 2006

The purpose of this study was to find out the kinematical characteristics of arm's basic position in ballet. In order to achieve the purpose of the study, 3D cinematographic analysis was conducted with a ballerina who might performed the perfect arm's basic position. According to the results of this study, it was appeared that the shoulder kept about 78%-82%, the elbow kept about 62%-96%, the wrist kept 52%-109%, and finger kept 48%-110% with the height. Also, movement was formed with $21^{\circ}-77^{\circ}$ of the upper arm angle, $106^{\circ}-164^{\circ}$ of the elbow, $125^{\circ}-140^{\circ}$ of the wrist, and $83^{\circ}-160^{\circ}$ of the shoulder. The left-right ratio of the total arm angle was 98% in the first, second, and third position, and 100% in the forth position. The angle of arm gradient was remained $-68^{\circ}$ in the first position, $-27^{\circ}$ in the second position, $73^{\circ}$ in the third position, and $-11^{\circ}$ in the forth position. Based on the results mentioned above, balance and symmetry of both arms was an important factor in those four positions. Although it is impossible to maintain the position like robot, it may be a good performance if a certain level of extent was remained With respect to this point of view, it may be a good position if the difference between right and left arm in each joint can be remained within 2%. Angle also was an important factor that if the difference in total angle can be remained within 2% it may be an excellent position, there was difference of right and left based on the joint though. Therefore, practice and instruction to make a perfect symmetry as much as possible were needed Also, it would be a good movement if position and angle of joint within 2% difference of right and left arm can be remained In turn, because ballet is movement with expression of the body, beauty of the body and balance of the movement have to be harmonized for beautiful performance. Therefore, it would be a meaningful future study considering the body condition and movement of ballerina to define the beauty.

• 한국전산유체공학회지
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• 제19권3호
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• pp.69-76
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• 2014

The shock buffet on a transonic transport aircraft are negative factors that reduce the aerodynamic performance of aircraft. The parametric studies were performed for position of nacelle/pylon to estimate the trend of flow mechanism under the wing that affects shock buffet. To generate external mesh of aircraft configuration that change the position of nacelle, snappyHexMesh provided in OpenFOAM was applied. Implicit density-based solver(ISAAC) was used for flow analysis. The change of nacelle position along horizontal direction dynamically affected the aerodynamic performance of transonic transport aircraft as comparing that of vertical direction. As a result of the parametric study of nacelle/pylon position, it was confirmed that the optimal position of nacelle can be obtained by aerodynamic design.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2007년도 학술대회 논문집 전문대학교육위원
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• pp.160-164
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• 2007

MRAS observer, which is based on adaptive control theory, estimates speed and position by using optimal observer gains on the basis of Lyapunov stability theory. However, in case of MRAS theory, position estimation error is in existence because of non-linearity for inductance variation and limit cycles for position estimation. The adaptive sliding observer based on the variable structure control theory estimates the speed and position for zero of estimation error by using the sliding surface equal to the error between speed and position estimation. The binary observer estimates the rotor speed and rotor flux with alleviation of the high-frequency chattering, and retains the benefits achieved in the conventional sliding observer, such as robustness to parameter and disturbance variations. The speed and position sensorless control of SRM under the load and inductance variation is verified by the experimental results.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2006년도 심포지엄 논문집 정보 및 제어부문
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• pp.339-341
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• 2006

This paper proposes a method of container position measurement using automatic landing system that is estimated by a laser range finder. In the most of container position measurement methods, CCD cameras or laser scanners have been used to get the source data. However those sensors are not only weak for disturbances, for examples, the light, fog, and rain, but also the system cost is high. When the spreader arrives the goal position, it is still swung by inertia or by wind effect. In this paper, the spreader swung data have been used to find the container position. The laser range finder is equipped in the front side of spreader. It can measure distance and relative position between spreader and container. This laser range finder can be rotated as desired by a motor. And a tilt sensor is equipped on the spreader to measure spreader sway. We estimate the relative position information between the spreader and a container using the laser range finder and tilt sensor through the geometrical analysis.

• Journal of Electrical Engineering and Technology
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• 제11권4호
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• pp.889-897
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• 2016

This paper presents an improved approach for compensating rotor position signal displacement in brushless DC (BLDC) motors with misaligned hall-effect sensors. Typically, the hall-effect sensors in BLDC motors are located in each phase and positioned exactly 120 electrical degrees apart. However, limitations in mechanical tolerances make it difficult to place hall-effect sensors at the correct location. In this paper, a position error compensator to counteract the hall-effect sensor positioning error is proposed. The proposed position error compensator uses least squares error analysis to adjust the relative position error and back-EMF information to reduce the absolute offset error. The effectiveness of the proposed approach is verified through several experiments.