• 대한치과의사협회지
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• 제18권3호통권132호
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• pp.197-200
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• 1980

This study was undertaken to investigate the form and position of the mandible of upper prognathism in relation to craniofacial complex. The subjects consist of 20 males and 39 females with Class II, Division 1 malocclusion and measurements were achieved on lateral cephalograms. The results were a follows. 1. Infradentale was situated anteriorly to orbital plane, but point B, pogonion and menton were situated posteriorly. 2. Development of chin point area of female was poor than that of male. 3. In case of facial angle was large, ramus angle tend to be small, but gonial angle had tendency to be large.

• Nuclear Engineering and Technology
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• 제52권6호
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• pp.1271-1276
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• 2020

The geometrical efficiency of a source-to-detector configuration is considered to be necessary in the calculation of the full energy peak efficiency, especially for NaI(Tl) and HPGe gamma-ray spectroscopy detectors. The geometrical efficiency depends on the solid angle subtended by the radioactive sources and the detector surfaces. The present work is basically concerned to establish a new mathematical approach for calculating the solid angle and geometrical efficiency, based on conversion of the geometrical solid angle of a non-axial radioactive point source with respect to a circular surface of the detector to a new equivalent geometry. The equivalent geometry consists of an axial radioactive point source with respect to an arbitrary elliptical surface that lies between the radioactive point source and the circular surface of the detector. This expression was extended to include coaxial radioactive circular disk source. The results were compared with a number of published data to explain how significant this work is in the efficiency calibration procedure for the γ-ray detection systems, especially in case of using isotropic radiating γ-ray sources in the form of point and disk shapes.

• 한국군사과학기술학회지
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• 제20권4호
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• pp.497-504
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• 2017

This paper proposes a method to measure the airburst height by utilizing a high speed camera. This method might be applied to the test of which flight target is alive after the burst. The proposed method consists of four main steps. The first step is to compute the impact point using the sea surface height. The second step is to compute the height of burst (HOB) by using the distance from the camera to the impact point. This could be different from the real explosion height. That is because the distance from the camera to the burst point is not the same as it from the camera to the impact point. Therefore, the third step is to calculate the approach angle of the flight target with respect to the installed camera. Then, the last step is to compensate the computed height by using the approach angle. The result of the proposed method is compared with it from the triangulation. In this paper, the HOB error is also analyzed regarding the approach angle difference. Based on this analysis, the camera position might be suggested for error reduction.

• 한국정밀공학회지
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• 제29권9호
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• pp.986-994
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• 2012

This paper is concerned with the application of the vision control algorithm with weighting matrix in robot point placement task. The proposed vision control algorithm involves four models, which are the robot kinematic model, vision system model, the parameter estimation scheme and robot joint angle estimation scheme. This proposed algorithm is to make the robot move actively, even if relative position between camera and robot, and camera's focal length are unknown. The parameter estimation scheme and joint angle estimation scheme in this proposed algorithm have form of nonlinear equation. In particular, the joint angle estimation model includes several restrictive conditions. For this study, the weighting matrix which gave various weighting near the target was applied to the parameter estimation scheme. Then, this study is to investigate how this change of the weighting matrix will affect the presented vision control algorithm. Finally, the effect of the weighting matrix of robot vision control algorithm is demonstrated experimentally by performing the robot point placement.

• 전기전자학회논문지
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• 제20권4호
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• pp.344-350
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• 2016

본 논문에서는 움직이는 영상에 대해 물리적인 회전이 발생하였을 때, 빠른 보정을 처리하기 위해 회전된 영상의 회전 각도를 고속으로 처리하기 위한 ECP (Extreme Contour Point) 알고리즘의 FPGA (Field Programmable Gate Array) 하드웨어 설계를 최적화하였고, XC7Z020 xc7z020-3clg400 FPGA 보드와 xilinx 14.2 툴을 사용하여 검증하였다. 잘 알려진 각도 산출 알고리즘인 CORDIC (Coordinate Rotation Digital Integrated Computation)과 비교하여 4ns의 유사한 동작 속도 안에서 CORDIC 대비 Registers는 108%, Look Up Tables (LUTs)는 91% 감소하는 등 하드웨어 비용이 우수함을 확인하였다.

• 한국운동역학회지
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• 제17권2호
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• pp.157-166
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• 2007

This study was to compare the major kinematic factors between the success and failure group on performing the back somersault motion in floor exercise. Three gymnasts(height : $167.3{\pm}2.88cm$, age : $22.0{\pm}1.0years$, body weight : $64.4{\pm}2.3kg$) were participated in this study. The kinematic data was recorded at 60Hz with four digital video camera. Two successful motions and failure motions for each subject were selected for three dimensional analysis. 1. Success Trail It was appear that success trail was larger than failure group in projection velocity, but success trail was smaller than failure trail in projection angle. Also it was appear that success trail was longer than failure group in the time required. Hand segment velocity and maximum velocity in success trail were larger than those in failure trail, and this result was increasing the projection velocity and finally increasing the vertical height of center of mass. At the take-off(event 2), flection amount of hip and knee joint angle was contributed to the optimal condition for the take-off and at the peak point, hip and knee joint angle was maximum flexed for reducing the moment of inertia. Also in this point, upper extremities of success trail extended more than those of failure trail. in this base, success trail in upward phase(p3) 2. Failure Trail It was appear that failure trail was smaller than success trail in projection velocity, but failure trail was larger than success trail in projection angle. Also it was appear that failure trail was more short than success trail in the time required. Hand segment velocity and maximum velocity in failure trail were smaller than those in success trail, and this result was reducing the projection velocity and finally reducing the vertical high of center of mass. At the take-off(event 2), flection amount of hip and knee joint angle wasn't contributed to the optimal condition for the take-off and at the peak point, hip and knee joint angle wasn't maximum flexed for reducing the moment of inertia. Also in this point, upper extremities of failure trail didn't extended more than those of success trail.

• The Journal of the Acoustical Society of Korea
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• 제20권3E호
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• pp.25-30
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• 2001

In angle of arrival estimation, the direction of a signal is usually assumed to be a point. If the direction of a signal is distributed due to some reasons in real surroundings, however, angle of arrival estimation techniques based on the point source assumption may result in poor performance. In this paper, we consider angle of arrival estimation when the signal sources are distributed. A parametric source model is proposed, and the estimation techniques based on the well-known maximum likelihood technique is considered under the model. In addition, Various statistical properties of the estimation errors were obtained.

• 한국정밀공학회지
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• 제17권10호
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• pp.132-140
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• 2000

In conventional drilling, burr geometry can be changed according to the variation of drill geometry like point angle, rake angle. Step drilling is proposed to minimize the burr formation in drilling operation. The burr formed in first cutting can be removed in second cutting by the edge in step. The burr formed in second cutting by the edge in step can be minimized according to the change of geometry like, step angle and depth. The mechanism in step drilling is analyzed. Some step drills are applied to drilling the input shaft which is used for vehicle steering. To measure the burr formed in drilling, laser and height gage are used.

• The Korean Journal of Pain
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• 제14권2호
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• pp.207-210
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• 2001

Backgroud: Caudal blocks have been used for pain management in outpatient clinics. It is important to estimate the proper depth and angle in order to increase the success rate of the procedure. Methods: Data was collected from 60 patients who visited our pain clinic. We measured the depth of the needle's penetration and the angle of the needle at the insertion point when a caudal approach was confirmed by air flow method. We recorded age, sex, body weight and height, and calculated the ponderal index. Results: The depth from the skin to the caudal epidural space was a mean 2-4 cm ($3{\pm}0.4\;cm$). The angle at the needle insertion point was a mean 15-50 degree ($34.9{\pm}6.8$ degree). Conclusions: If we use the mean depth and angle as a guide, complications during the caudal epidural procedure can be avoided.

• International Journal of Precision Engineering and Manufacturing
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• 제9권2호
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• pp.3-7
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• 2008

Vibratory conveyors are widely used in industry to transport granular materials and products. A theoretical point mass model for vibratory conveying was studied. The results agreed well with experimental observations. The model theory included the resting, sliding and flight states of the material. Each state was considered separately when determining the equations of motion. For the coefficients of restitution, values of zero for the normal component and 0.8 for the tangential component were found to be appropriate for modeling the collisions of the granular particles with the conveying surface. The vibration angle had a large influence on the mode and rate of transport. There was an optimum vibration angle for a given set of conditions. The optimum vibration angle decreased and was better defined as the coefficient of friction increased. The results suggest the existence of an optimum dimensionless track acceleration (throw number), which does not support general industrial practice in which the track acceleration is limited when the feed cycle becomes erratic and unstable.