• 한국소음진동공학회논문집
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• 제13권10호
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• pp.743-750
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• 2003

The equivalent source method(ESM) is used for the calculation of the internal pressure field for an enclosure which can have arbitrary boundary conditions and nay include internal objects which scatter the sound field. The advantage of using ESM is that it requires relatively low computing cost and is easy to model the internal diffracting objects. Typical ESM modeling uses two groups of equivalent source positions. One group includes the first order images of the source inside the enclosure. The Positions of the other group are usually on a spherical surface some distance outside the enclosure. The normal velocity on the surfaces of the enclosure walls is evaluated at a larger number of positions than there are equivalent sources. The sum of the squared difference between this velocity and the expected is minimized by adjusting the strength of the equivalent sources. This study is on the optimal far field sources positions when using the equivalent source method. In general, the far field sources are evenly distributed on a surface of a virtual sphere which is centered at the enclosure with a sufficiently large radius. In this study. optimal far field source locations are searched using simulated annealing method for various radii of spheres where far field sources are located. Simulation results showed that optimally located sources with adequate distance away from the enclosure center gave better result than sources with even distribution even with a smaller number of far field sources.

• 한국음향학회지
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• 제23권5호
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• pp.370-375
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• 2004

본 논문에서는, 미지 위치의 원거리 능동음원을 이용하여 해저고정형 선배열 센서에 대한 3차원 배열형상추정 기법을 제안하였다. 본 연구는 센서에 도달하는 음파가 평면파라는 가정 하에 기준센서와 나머지 센서간의 음파도달 시간지연, 센서위치 및 입사각과의 선형방정식의 해를 반복적 최소자승법에 의해 구함으로서 센서위치 추정이 가능하다. 제안된 기법의 타당성을 검증하기 위해 컴퓨터 시뮬레이션과 실제 해상실험을 수행하였으며, 이론적 분석을 통하여 음원 위치 분포에 따른 성능 및 시간지연 오차에 따른 센서위치 추정 성능을 분석하였다.

• 대한물리의학회지
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• 제6권1호
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• pp.51-58
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• 2011

Purpose : This study was designed to identify the effects of carrying bag positions (None, left hand, right hand, left shoulder, right shoulder) on static balance. Methods : Fourteen healthy adult females participated in the this study. The exclusion criteria were orthopedic or neurologic disease, predominant left side. Measurements were performed initial effects. Results were evaluated by OSI, APSI, and MLSI in the biodex stability system. Results : There are among the three assessments (overall stability index(OSI), antero-posterior stability index (APSI), medio-lateral stability index(MLSI) significants difference for the carrying bags positions (None bag, left hand, right hand, left shoulder, right shoulder)(p<.05). The post-hoc test revealed a significant difference between none bag and both left hand and left shoulder in the OSI, APSI, MLSI (p<.05). Also, comparing the carrying positions significant difference between right hand and both left hand and left shoulder in the MLSI (p<.05). Conclusion : The results suggest that none dominant side with carrying bag improve more imbalance than none bag and right hand of dominant with carrying bag improve more balance than non dominant side. When comparing the four carrying bag conditions, right hand was more effective than another conditions in static balance.

• 동의생리병리학회지
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• 제25권4호
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• pp.728-733
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• 2011

This study was designed to analyze the results of stress index by heart rate variability test. The subjects were workers in the automobile manufacturing industry. The subjects consisted of 23,767 workers who had answered about questionnaires of a job position, age, smoking, drinking, exercise state and sex. The stress index(SI) and stress resistance(SR) were examined by SA3000P. We analyzed the differences of SI and SR according to job positions, ages, the state of smoking, drinking, exercise and sex by T-test or ANOVA with SPSS ver. 17.0. Regarding the differences of SI among job positions, the SI was highest in sales positions. Among ages, the SI was highest in 30s. In smoking, the SI was lower in non-smoking group. In drinking, there was no significant differences in SI. In exercise, the SI was lower in exercise group. In sex, there was no significant difference. The case of SR, SR was lowest in sales positions. Among ages, the SR was lowest in 40s. In smoking, the SR was lower in smoking group. In drinking, there was no significant differences in SR. In exercise, there was no significant difference. In sex, the SR was lowest in male. According to these results, we should establish the methods of controlling stress from the perspective of Korean traditional medicine.

• 대한치과교정학회지
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• 제45권6호
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• pp.275-281
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• 2015

Objective: To assess the accuracy of anterior tooth movement using clear aligners in integrated three-dimensional digital models. Methods: Cone-beam computed tomography was performed before and after treatment with clear aligners in 32 patients. Plaster casts were laser-scanned for virtual setup and aligner fabrication. Differences in predicted and achieved root and crown positions of anterior teeth were compared on superimposed maxillofacial digital images and virtual models and analyzed by Student's t-test. Results: The mean discrepancies in maxillary and mandibular crown positions were $0.376{\pm}0.041mm$ and $0.398{\pm}0.037mm$, respectively. Maxillary and mandibular root positions differed by $2.062{\pm}0.128mm$ and $1.941{\pm}0.154mm$, respectively. Conclusions: Crowns but not roots of anterior teeth can be moved to designated positions using clear aligners, because these appliances cause tooth movement by tilting motion.

• 한국재료학회지
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• 제22권11호
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• pp.581-586
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• 2012

The microstructure and mechanical properties of a copper alloy sheet processed by differential speed rolling (DSR) were investigated in detail. A copper alloy with thickness of 3 mm was rolled to a 50% reduction at ambient temperature without lubrication and with a differential speed ratio of 2.0:1. For comparison, conventional rolling (CR), in which the rolling speeds of the upper and lower rolls is 2.0 m/min, was also performed under the same rolling conditions. The shear strain of the sample processed by CR showed positive values at the positions of the upper roll side and negative values at the positions of the lower roll side. On the other hand, the sample processed by the DSR showed zero or positive shear strain values at all positions. However, the microstructure and mechanical properties of the as-rolled copper alloys did not show such significant differences between the CR and the DSR. The samples rolled by the CR and the DSR exhibited a typical deformation structure. In addition, the DSR processed samples showed a typical rolling texture in which {112}<111>, {011}<211> and {123}<634> components were developed at all positions. Therefore, it is concluded that the DSR was very effective for the introduction of a uniform microstructure throughout the thickness of the copper alloy.

• 국제물리치료학회지
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• 제9권1호
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• pp.1406-1412
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• 2018

This study aimed to measure the grip strength of the dominant and non dominant hands of right-handed normal adults in the supination, pronation, and neutral positions of the forearms. The subjects of this study were instructed to make the standard posture suggested by the American Society of Hand Therapists (ASHT) in order to minimize the impact of changes in the posture of the body as follows. The grips strength was statistically different between groups (p<.05). In the follow up test using Scheffe test, the grips in the neutral position and supinator position did not show any difference, while the grip in the pronation was smaller than those of the above two other positions. The grips of the mainly used forearm and non-mainly used forearm of the study target did not show any statistically significant difference in the neutral, supinator and pronation positions of the forearm. This study is expected to provide basic information for studying the impact of the positions of the forearms on grip strength, assessing the prehensility of patients in clinical settings, and setting therapeutic goals.

• 한국수소및신에너지학회논문집
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• 제27권6호
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• pp.685-692
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• 2016

Hydrogen will be a future eco-friendly energy source that can replace current fossil fuels However when hydrogen gas leaks and people inhale a lot of hydrogen gases, they can have fatal effects fell into comas. Therefore, we need to develop a safety technology and related guidelines for reducing risks of hydrogen leakage. In this regard, we carried out demonstration tests assuming a situation of hydrogen leakage. Before the experiments, we analyze the standards for governor facilities to check vent positions and sensor positions. Then, we select four types of ventilation structures and proceeds with the experiments of hydrogen leakage at 1 LPM and 1.5 LPM. Based on the experimental results, we propose the direction on optimization of vent positions and sensor positions in the hydrogen leakage situation.

• 대한기계학회논문집B
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• 제32권10호
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• pp.784-790
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• 2008

The feasibility and the accuracy of the correlation coefficient(CC) method for the determination of particle positions along the optical axis in digital particle holography were verified by alidation experiments. A traverse system with capable of high precision was used to move the particle objects by exact known distances between several different positions. The particle positions along the optical axis were calculated by the CC method and compared with their exact values to obtain the errors of the focal plane determination. The tested particles were 2D dots in a calibration target along with different sized glass beads and droplets that reflected and caused a three-dimensional effect. The results show that the CC method can work well for both the 2D dots and the 3D particles. The effect of other particles on the focal plane determination was also investigated. The CC method can locate the focal plane of particles with a high precision, regardless of the existence of other particles.

• 제어로봇시스템학회논문지
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• 제7권12호
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• pp.1015-1023
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• 2001

error behaviour can be considered as a linear combination of low amplitude random noise and abrupt jumps. The reason of jump appearance can be explained by the semi-shading effects(buildings, trees), jamming, high dynamic of vehicle and so on. This study describes the stand-alone GPS error jump smoothing algorithm which is developed based on the scalar adaptive filter. The algorithm consists of the coarse jump smoothing and the fine jump smoothing. On the coarse smoothing step, GPS velocities or position differences are used as the measurement for the scalar adaptive filter. The purpose of adaptive filter is to smooth the jump errors. The coarse positions are detennined by the integration of smoothed velocities. On the fine smoothing step, the differences between GPS positions and the coarse positions are smoothed by another scalar adaptive filter. The reason of fine smoothing is based on the facts that smoothing accuracy depends on the variance ofusefuJ signa\. The coarse smoothing which deal with the difference of positions provides the rough error removing. So the coarse smoothed velocities can have much more low amplitude than the raw ones. The fine smoothing procedure provides high quality of filtering process. Simulation results show the efficiency of proposed scheme.