• Journal of the korean Society of Automotive Engineers
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• v.12 no.5
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• pp.76-84
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• 1990

To study diesel fuel spray behavior, an experimental study was undertaken to investigate injection characteristics in vary ing back pressure and atomization mechanism in a non-evaporating diesel spray. Generally, injection characteristics is the curve of fuel flow plotted against time. The area under this curve is equal to the total quantity of fuel discharged for one injection. The method that measures rate of injection is long tube-type fuel rate indicator. Diesel spray injected into a quiescent gaseous environment under high pressure is observed by taking high speed camera by the focused shadow photographs. The results show that, at the start of injection, as the injected fuel rushes into the quiescent atmosphere the spray angle becomes large. Finally the spray stabilizes at a constant cone angle. Spray penetration length increases with the injection pressure.

• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 2001.04a
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• pp.108-119
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• 2001

The Spectral Analysis of surface Waves(SASW) Method has a great has a great potential for rapid determination of shear wave velocity profile of ground. However, it has an inherent limitation in the interpretation of test results due to the assumption that the ground is layered horizontally. The reason of the assumption is that difficulties exist in obtaining analytical solutions of wave equation when a soil system is composed of inclined soil layer. In this study, a finite-element method has been employed to assess the effects of dip angle and stiffness contrast of inclined soil layers and the testing direction on the dispersion curve. The propagation of wave front in the inclined soil layer was also investigated. The results indicated that the influence of dip angle on the dispersion curve is getting obvious as the dip angle increases and the propagation of wave front in the inclined layer also entirely different compared with the case of the horizontal layer.

• Journal of radiological science and technology
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• v.28 no.4
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• pp.327-332
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• 2005

The purpose of this Study was to investigate the prevalence rate of idiopathic scoliosis to the students from the elementary to the university in S city of Chung-Nam using 100 mm Mirror Camera radiation indirect examination units, with on age range of between eight and thirteen (1.526 subjects), fourteen and sixteen (462 subjects), seventeen and eighteen (291 subjects), nineteen and twenty four(508 subjects) and total of 2,787 participants with the 590 male subjects and 2,197 female subjects. The results of this study can be summarized and compared the primary examination with the secondary test of greater than $10^{\circ}$of Cobb's Angle were obtained as follows; 1. Indirect Examination were conducted to find idiopathic scoliosis amomg total 2.787 subjects, 257 subjects (9.2%) who showed positive sign greater than $10^{\circ}$in the Cobb's Angle ; below age of thirteen (132 subjects), between fourteen and sixteen (52 subjects), seventeen and eighteen (35 subjects), nineteen and twenty four (38 subjects). The $x^2-test$ analysis of Indirect Examination showed no statistical significant difference association between the age range and $10^{\circ}$Cobb's Angle of spinal curve(P>0.059). 2. The numbers of idiopathic scoliosis of greater than $10^{\circ}$Cobb's Angle of spinal curve in the primary examination were observed in 147 subjects (57.2%) at the Thoracolumbar region, 81subjects (31.5%) at the Thoracic region, 20 subjects (7.8%) at the Cervicothoracic region, 7 subjects (2.7%) at the Lumbar region, 2 subjects (0.8%) at the Cervical region. So, the large numbers were Thoracolumbar region, 183 participants (71.2%) showed the right side curve of scoliosis and 74 participant (28.8%) showed the left side curve of scoliosis. 3. The main region of the pain in one's own self more than $10^{\circ}$ Cobb's angle of spinal curve were no pain 219 subjects (85.2%), 18 subjects (7.0%) at the Lumbar region, 9 subjects (3.5%) at the Cervical region, 7 subjects (2.7%) at the Thoracic region, 2 subjects (0.7%) at the shoulder girdle region, 1 subjects (0.39%) at the pelvis and whole body region. There was statistical significant difference association between the Cobb's Angle of spinal curve and the main pain region of one's (P<0.006). This study may be significant to an early stage investigate of the prevalence rate of idiopathic scoliosis in the juveniles using 100 mm Mirror Camera radiation indirect examination units. The results of this study help that the students in a stage on growth the basis of data early discovery and therapy of idiopathic scoliosis.

• The Journal of Korean Physical Therapy
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• v.14 no.1
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• pp.187-195
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• 2002

This study was performed to assess the efficacy of Activator for the patient with chronic neck pain. Mail, 26 years old, is treated with Activator, which was applied for 15 minutes every two days during the 4 weeks. The results of this study are as follows: 1. The treated case compared with the previous case showed that R.O.M particularly increased in flexion and extension. 2. The atlas/skull angle compared with the previous case showed that the angle increased from $0.8^{\circ}$ to $1.5^{\circ}$. In the atlas/skull, normal angle is $5.6^{\circ}$. 3. The angle of cervical curve lordosis compared with the previous case showed that the angle increased from $38.3^{\circ}$ to $48.1^{\circ}$. In the healthy spine, the angle is $42.0^{\circ}$. 4. The anterior curvature compared with the previous case showed that curve radii decreased from 7,220mm to 200mm. In the spine, normal curvature is 165mm. 5. Rush Jackson's angle compared with the previous case showed that the angle increased from $14.8^{\circ}$ to $29.1^{\circ}$. In the healthy spine, normal angle is $39.9^{\circ}$. We can not find significant level for Activator, but it is considered that activator method of chiropractic technique is effective.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.17 no.2
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• pp.207-211
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• 2004

We have performed computer simulation to obtain a globa1 optimization of power consumption and viewing angle characteristic of reflective twisted nematic (R-TN) mode liquid crystal display (LCD) with sin81e polarizer and λ/4 plate. Our studies shout that with increasing the twist angle, a steepness of reflectance-voltage curve increase, operation voltages decreases, the region where contrast ratio (CR) greater than 10 increases but the reflectance of the white state starts to decrease at above the twist angle of 75$^{\circ}$. Above the twist angle of 90$^{\circ}$, the R-TN mode LCD shows the most favorable combination of low consumption and good viewing angle characteristic.

• Journal of Biosystems Engineering
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• v.12 no.3
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• pp.42-49
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• 1987

The threshing action of the head-fed type threshing unit occurs mainly by the impact between threshing tooth and grains. It may be therefore the most fundamental step to calculate the time and order of the occurrance of impact by the tooth for predicting the performance of threshing unit. The threshing teeth arrangement was defined by length and diameter of threshing dram, number of spiral arrays, number of threshing teeth by kind per one spiral array, number of windings of spiral array around the threshing drum, delay angle of impact line. The linear equations for locus of left and right margin of paddy bundle, spiral array, impact line on the development figure of the threshing drum were expressed by fastors of the threshing teeth arrangement. In the computer program, the teeth which inflict impact were searched successively along the impact line. Searching range and impact condition were defined by the relation between four linear equations. If the impacting tooth was found, time and the kind of threshing tooth was derived from the coordinate of the threshing tooth. At this time the unit torque curve was accumulated on the array of computer memory. At last the completed torque curve of threshing drum shaft was described on the computer screen. Remarkably the peack valae and fluctuation of torque curve was decreased by adopting the delay angle of impact line.

• Journal of Institute of Control, Robotics and Systems
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• v.19 no.12
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• pp.1152-1159
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• 2013

This paper proposes an effective walking system for a hexapod robot on uneven terrain. To overcome the deficiencies of two-pair walking systems, which are effective on even terrain, the use of only three legs changes the steps required for movement. The proposed system receives feedback data from switches attached to the bottom of the legs and gyro sensor to carry out stable walking using the Bezier curve algorithm. From the coordinates of the Bezier curve, which guarantees the circular motion of legs, the motor's angle value can be obtained using inverse kinematics. The angle values are sent to each motor though RS-485 communication. If a switch is pushed by the surface during navigation in the Bezier curve pattern, the robot is designed to change its circular course. Through the changed course, each leg can be located on an optimal surface and the wobble phenomenon is reduced by using a normal vector algorithm. The simulation and experiment results show the efficiency of the proposed algorithm.

• Honam Mathematical Journal
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• v.46 no.2
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• pp.209-223
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• 2024

In this paper, we investigate the spatial quaternionic expressions of the ruled surfaces whose base curves are formed by the Smarandache curve. Moreover, we formulate the striction curves and dralls of these surfaces. If the quaternionic Smarandache ruled surfaces are closed, the pitches and angle of pitches are interpreted. Finally, we calculate the integral invariants of these surfaces using quaternionic formulas.

• Journal of Korean Society of Steel Construction
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• v.12 no.1 s.44
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• pp.65-73
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• 2000

The behavior of double angle connections is analyzed by 3D finite element method using ABAQUS(ver 5.8). Moment-rotation curves for the connections are generated, as well as stress distribution for angle and bolt. Double angle connections have various angle thickness, gage distance and number of bolt. Parameters, such as initial stiffness, plastic tiffness, reference load and curve shape parameter were obtained by regression method using Richard's formula. These parameter lead to predict nonlinear behavior of double angle connection. Design curves giving the parameters of the moment-rotation curves are generated. These parameters are primarily a function of the angle thickness, gage distance and the number of bolts in the connection. Using these parameters, connection moment and its ratio to the full plastic moment capacity Mp of the beam are calculated.

• Transactions of the Korean Society of Automotive Engineers
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• v.11 no.1
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• pp.193-200
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• 2003

This paper proposes a novel algorithm to recognize the curve of a structured road. The proposed algorithm uses an LCF (Lane Curve Function) obtained by the transformation of a parabolic function defined on world coordinate into image coordinate. Unlike other existing methods, the algorithm needs no transformation between world coordinate and image coordinate owing to the LCF. In order to search for an LCF describing the lane best, the differential comparison between the slope of an assumed LCF and the phase angle of edge pixels in the LROI (Lane Region Of Interest) constructed by the LCF is implemented. As finding the true LCF, the lane curve is determined. The proposed method is proved to be efficient through various kinds of images, providing the reliable curve direction and the valid curvature compared to the real road.