• Transactions of the Korean Society of Mechanical Engineers B
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• v.22 no.1
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• pp.131-138
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• 1998

Conventional yaw functions are compared with actual response of a hot wire to various yaw angles, and a new function is proposed, which can be applied at large yaw angles and low velocities. To compare the accuracy of the new yaw function with those of the conventional ones, measurements are made for the jet flow at the nozzle exit and at .chi./D=15 with an X hot-wire probe. In the potential core, the flow angles reduced by the present function, ideal angle method and full velocity-angle method are shown to be more accurate than those reduced by the cosine function and Hinze's formula. No matter which yaw functions are used, the profiles of mean velocity and turbulence intensity show little discrepancy at .chi./D=15. However, there is a significant difference between the probability density functions obtained by the present function, ideal angle method and full velocity-angle method and those obtained by the cosine function and Hinze's formula.

• Journal of The Korean Society of Integrative Medicine
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• v.1 no.1
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• pp.33-43
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• 2013

Purpose : The study was designed to identify the change of body alignment according to surface during walking with backpack. Methods : Healthy twenty people(10 men & 10 women) participated in this study. The exclusion criteria were orthopedic and neurologic disease. Initial alignment measurements were performed. Results were evaluated by angle and range from earlobe to acromion, acromion to malleolus and earlobe to malleolus in the GPS system. Results : On the hard surface, the distance and angle from malleolus to earlobe increased after walking with backpack which is 20 % of weight(p<.05). In addition the distance from malleolus to acromion and the angle from earlobe to acromion increased(p<.05). On the soft surface, on the other hand, the distance and angle from malleolus to earlobe decreased after walking with backpack which is 20 % of weight(p<.05). There was no relationship between the change of the surface and the body's alignment(p>.05). Conclusion : Consequently, the body alignment was changed by backpack which is 20 % of weight, but body alignment wasn't changed by the surface. So more study need to be surveyed regard of this.

• Journal of the Korean Society for Precision Engineering
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• v.28 no.9
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• pp.1070-1077
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• 2011

This study intends to assess the defect in the weld zone of titanium grade 2 plate in terms of acoustical anisotropy based on the angle beam method. Depending on the rolling direction, the ratio of wave velocity was found to be 1.08 and the difference in the angle of refraction was more than seven degrees, confirming the presence of acoustical anisotropy. Thus for measuring the length of defect in the weld zone of the titanium plate (thickness of 10mm), the distance amplitude characteristics curves of titanium, TDACC-R and TDACC-T were constructed for the measurements in consideration of the acoustical anisotropy on CRT of the ultrasonic testing equipment. As a result, when the distance amplitude characteristics curve corresponds to the rolling direction, the length of defect was close to the actual measurement within 1mm and when different, the difference was found to be over 4mm. It was affirmed that the acoustical anisotropy should be taken into consideration when measuring the length of defects in the weld zone of the titanium plate with the presence of acoustical anisotropy.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.34 no.10
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• pp.61-70
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• 2006

A Supersonic air intake model was designed for the high performance ramjet and dual-mode scramjet engine to operate at Mach 4 flight condition. The air intake was tested in the blowdown-type wind tunnel of Kyushu University to identify the internal flow characteristics corresponding to the flight parameters such as the back pressure, angle of attack and angle of yaw. Flow visualization was achieved by the Schlieren and oil flow visualization techniques. The intake performance was analyzed quantitatively based on the surface pressure and total Pressure measurements. The experimental results were compared with the computational fluid dynamics results. The present study exhibits the fundamental but rarely found experimental results of the high Mach number supersonic air intake.

• The korean journal of orthodontics
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• v.4 no.1
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• pp.13-19
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• 1974

In orthodontic view points, there were a few attempts to describe on the mandibular rest position with roentgenocephalometric studies for the persons with malocclusion. The purpose of the present study was to evaluate and interpret the difference in each of the Angle's classification of the malocclusion. The author has selected 115 malocclusion patients of the both sexes as subjects, whose dental ages were from III A. Two lateral cephalometric head films were taken mandible at rest and with the teeth in occlusion utilizing the Broadbent-Bolton cephalometer. Their linear and angular measurements were made directly. The author obtained the following results: 1) The change in the incisal overbite was of $-2.32\~-3.36mm$, and the overjet decreased similiarly in each class of the malocclusion. 2) The range of free-way space was of $1.97\~3.56mm$, and showed prominent in the Angle's class III malocclusion. 3) In the rest position, the mandible showed backward displacement, and it was prominent in the Angle's class III malocclusion. 4) In the change of Ar-Gn, the class I and II showed more increase of distance-than the class III. 5) In the change of ${\angel}SNL_1L_1'$, the class III showed smaller angle than the class I and II. 6) There was no significant difference between the male and female in each class of the malocclusion.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.27 no.8
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• pp.693-700
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• 2016

In this paper, it is represented that equations for design of linear interferometer antenna when the 3 dB beamwidth is only region of interest. Using the equations, relationships between angle measurement ambiguity and element antenna spacings are described. And then, operating frequency, angle measurement accuracy, beamwidth, correct measurement probability are calculated for five antennas interferometer to measure azimuth and elevation angle. The interferometer antenna was designed and fabricated using the calculated parameters. The angle measurement accuracy were $0.01^{\circ}$ and $0.016^{\circ}$ for azimuth and elevation axes with 99 % probability of doing measurements correctly which means that ambiguous solution did not occur more than 1 % of the time. These results validated the equations and design procedures.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.14 no.8
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• pp.709-717
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• 2004

The diesel engine is often a serious excitation source in ships. Both the varying cylinder gas forces and the reciprocating and rotating mass forces associated with the crank and the connecting rod mechanism produce ample possibilities for excitation of the engine structure itself, the shafting, the surrounding substructures as well as the hull girder. This paper presents a guide for optimization of excitation forces produced by the marine propulsion 2-stroke diesel engine. The computational program for predicting the excitation forces is developed and applied to 2-stroke in-line engines. The object function is defined as the work done by every cylinder excitation force which is related to the mode shape of the diesel engine system, especially in the torsional vibration of the shafting. As a practical application of the presented method. the crank angle of 7 cylinder 2-stroke engine is optimized to reduce torsional vibration stresses on the shafting. Compared with the regular firing angle, about 60 ％ of the 4th order torsional vibratory stress on the propeller shaft can be reduced by optimizing the crank angle irregularly. The usefulness of the presented optimization method is confirmed by the measurements.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.2 no.4
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• pp.279-287
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• 1990

An experimental study of the heat transfer characteristics between circular water jet and cylindrical inner surface is presented. The ratios of the semi-cylinder's inner diameter and the nozzle outlet diameter were varied parametrically, as were the Reynolds number and the supplementary water heights. The measurements showed that cirucmferential distribution of the heat transfer coefficient peaked at the stagnation point and, there occurred a kind of a secondary maximum of heat transfer that moved toward to stagnation point as the ratio d/D increased. The local heat transfer coefficient increases as the Reynolds number becomes larger, and the rate of increase is subjected to the influence of d/D & position of angle. Also, optimum heights of supplementary water which brings about the augmentation of heat transfer are S/D=1 for the stagnation point, the position of $15^{\circ}$ & $30^{\circ}$ angle, but for the positions of $45^{\circ}$ angle (d/D=10~11.67), $60^{\circ}$ & $75^{\circ}$ angle, the heat transfer coefficients in the case of using supplementary water are smaller than simple jet (S/D=0).

• Journal of Electrical Engineering and Technology
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• v.8 no.4
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• pp.899-910
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• 2013

This paper presents a novel lateral stability control system for electric vehicle based on sideslip angle estimation through Kalman filter using the integration of a single antenna GPS receiver and yaw rate sensor. Using multi-rate measurements including yaw rate and course angle, time-varying parameters disappear from the measurement equation of the proposed Kalman filter. Accurate sideslip angle estimation is achieved by treating the combination of model uncertainties and external disturbances as extended states. Active front steering and direct yaw moment are integrated to manipulate sideslip angle and yaw rate of the vehicle. Instead of decoupling control design method, a new control scheme, "two-input two-output controller", is proposed. The extended states are utilized for disturbance rejection that improves the robustness of lateral stability control system. The effectiveness of the proposed methods is verified by computer simulations and experiments.

• Journal of Fashion Business
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• v.19 no.3
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• pp.130-143
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• 2015

By studying 3-D virtual human modeling, motion-capturing and clothing simulation for easier and safer work clothes development, this research aimed (1) to categorize heavy manufacturing work motions; (2) to generate a 3-D virtual male model and establish painting work motions within a 3-D virtual clothing simulation system through computerized body scanning and motion-capturing; and finally (3) to suggest simulated clothing images of painting work clothes developed based on virtual male avatar body measurements by implementing the work motions defined in the 3-D virtual clothing simulation system. For this, a male subject's body was 3-D scanned and also directly measured. The procedures to edit a 3-D virtual model required the total body shape to be 3-D scanned into a digital format, which was revised using 3-D Studio MAX and Maya rendering tools. In addition, heavy industry workers' work motions were observed and recorded by video camera at manufacturing sites and analyzed to categorize the painting work motions. This analysis resulted in 4 categories of motions: standing, bending, kneeling and walking. Besides, each work motion category was divided into more detailed motions according to sub-work posture factors: arm angle, arm direction, elbow bending angle, waist bending angle, waist bending direction and knee bending angle. Finally, the implementation of the painting work motions within the 3-D clothing simulation system presented the virtual painting work clothes images simulated in a dynamic mode.