• Journal of the Korea Safety Management & Science
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• v.3 no.2
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• pp.181-188
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• 2001

This paper deals with a newly developed direction indicator system of a car which displays left turn and U-turn signal differently, so that the following driver can identify the intent of the next car ahead easily. In general, when a car want to change its direction, the driver move the blinker lever below the steering wheel up or down. However, as the left turn and U-turn signal are the same, there always be the risk of rear-end collision by misinterpreting U-turn signal as left turn signal. In this paper, a new direction indicator system which differentiates left turn and U-turn signal is developed. The left turn signal is the same as before, but when a driver want to U-turn, an additional U-turn signal blinks at the rear of the car. By identifying the direction signals clearly, the developed system is expected to alleviate the risk of car accident.

• Tribology and Lubricants
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• v.31 no.3
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• pp.125-140
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• 2015

In this paper, we present the results of the wear analysis of journal bearings on a stripped-down single-cylinder engine during start-up and coast-down by motoring. We calculate journal bearing wear by using a modified specific wear rate considering the fractional film defect coefficient and load-sharing ratio for the asperity portion of a mixed elastohydrodynamic lubrication (EHL) regime coupled with previously presented graphical data of experimental lifetime linear wear in radial journal bearings. Based on the calculated wear depth, we obtain a new oil film thickness for every crank angle. By examination of the oil film thickness, we determine whether the oil film thickness at the wear scar region is in a mixed lubrication regime by comparing dimensionless oil film thickness, h/σ, to 3.0 at every crank angle. We present the lift-off speed and the crank angles involved with the wear calculation for bearings #1 and #2. The dimensionless oil film thickness, h/σ, illustrates whether the lubrication region between the two surfaces is still within the bounds of the mixed lubrication regime after scarring of the surface by wear. In addition, we present in tables the asperity contact pressure, the real minimum film thickness at the wear scar region, the modified specific wear rate, and the wear angle, α, for bearings #1 & #2. To show the real shape of the oil film at wear scar region, we depict the actual oil film thickness in graphs. We also tabulated the ranges of bearing angles related with wear scar. We present the wear volume for bearings #1 and #2 after one turn-on and turn-off of the engine ignition switch for five kinds of equivalent surface roughness. We show that the accumulated wear volume after a single turn-on and turn-off of an ignition switch normally increases with increasing surface roughness, with a few exceptions.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2007.10a
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• pp.93-95
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• 2007

Studies on ski-end shape control at the top end of rolling plate in heavy thick plate mill by using FEM analysis and measuring system have been performed. Plate shape behaviour at the top-end on rolling by the two different methods in finishing rolling process has been observed. One is to minimize the height of ski-end by using pass line based on the relational model between shape factor and pick-up and the other one is to prevent turn down problem caused by the impact between table roller and down bended plate on rolling by using roll speed difference. To minimize the height of ski-end, the prediction models based on the FEM analysis and measuring data was developed. The control method of ski - end shape on finishing rolling process was applied in actual mill and the height of ski-end was reduced by about 50% compared with conventional operation.

• Journal of Korean Society of Transportation
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• v.14 no.3
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• pp.45-59
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• 1996

The shortest path algorithm for route guidance is implicitly required not only to support geometrical variations of transportation network such as U-TURN or P-TURN but to efficiency search reasonable routes in searching mechanism. The purpose of this paper is to integrate such two requirements ; that is, to allow U-TURN and P-TURN possibilities and to cut down searching time in locating routes between two points (origin and destination) in networks. We also propose a new type of link searching algorithm which can solve the limitation of vine building algorithm at consecutively left-turn prohibited intersections. The test site is a block of Gangnam road network that has some left-turn prohibited and allowed U-TURN intersections. Four models have been identified to be comparatively analyzed in terms of searching efficiency. The Models are as follows : (i) Model 1 - Link Searching Dijkstra Algorithm without Searching Area Extraction (SAE) ; (ii) Model 2 - Link Searching Dijkstra Algorithm with SAE ; (iii) Model 3 - Link Searching Bidirectional Dijkstra Algorithm without SAE ; and (iv) Model 4 - Link Searching Bidirectional Dijkstra Algorithm with SAE. The results of comparative evaluation show that Model 4 can effectively find optimum path faster than any other models as expected. Some discussions and future research agenda have been presented in the light of dynamic route guidance application of the urban ATIS.

• Journal of Advanced Marine Engineering and Technology
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• v.17 no.4
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• pp.11-19
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• 1993

The experimental study was carried out to investigate the stability and the performance characteristics of the aero-valved pulsating combustion system with maximum operating capacity of 60KW. The effect of geometry of combustion system on the stable condition, the flammability limit, the total pressure oscillation amplitude, and the operating frequency can be identified, and the maximum turn-down-ratio is obtained up to 3.3. The total pressure oscillation amplitude can be controlled by tunning the length of the air inlet pipe. The empirical equation with which the operating frequency can be approximated is proposed and the discrepancy is within 5%. The volumetric efficiency is identified to be one of the important parameters determining the upper flammability limit and the maximum value of which is approximately 22%.

• Journal of the Korean Society of Combustion
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• v.9 no.1
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• pp.1-10
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• 2004

The results of a series of experiments executed by using two pilot-scale oxy-fuel burners are presented. The oxy-fuel burners are designed for maximum capacity of 50,000kcal/hr, 200,000kcal/hr and installed in the test furnace. The effects of turn-down ratio, excess oxygen ratio, nozzle exit velocity, injection angle, and swirl vane angle on the combustion characteristic are investigated. Temperature distributions are measured using R-type and Molybdenum sheathed C-type thermocouple at various points of the flame. The results showed that maximum temperature and mean temperature increase with the increase of turn-down ratio and momentum. The maximum flame temperature was increased about 35% compared to the case of equivalent air operated condition. In addition, optimum burner type, excess oxygen ratio and nozzle characteristics are obtained for this oxy-fuel glass melting furnace.

• Korean Journal of Applied Biomechanics
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• v.30 no.1
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• pp.17-25
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• 2020

Objective: The purpose of this study is to provide a better understanding of long turn mechanism by describing long turns after kinematic analysis and provide skiers and winter sports instructors with data through which they are able to analyze right postures for turns in skiing in a systematic, rational and scientific manner. Method: For this, a mean difference of kinematic variables (the center of gravity (CG) displacement of distance, trajectory, velocity, angle) was verified against a total of 12 skiers (skilled and unskilled, 6 persons each), regarding motions from the up-start to down-end points for long turns. Results: First, concerning the horizontal displacement of CG during a turn in skiing, skilled skiers were positioned on the right side at the upstart and edge-change points at a long turn. There was no difference in anteroposterior and vertical displacements. Second, in terms of CG-trajectory differences, skilled skiers revealed a significant difference during a long turn. Third, regarding skiing velocity, skilled skiers were fast at the edge-change and maximum inclination points in long turns. Fourth, there was no difference in a hip joint in terms of a lower limb joint angle. In a knee joint, a large angle was found at the up-start point among skilled skiers when they made a long turn. Conclusion: In overall, when skilled and unskilled skiers were compared, to make a good turn, it is required to turn according to the radius of turn by reducing weight, concerning the CG displacement. Regarding the CG-trajectory differences, the edge angle should be adjusted via proper inclination angulation. In addition, a skier should be more leaned toward the inside of a turn when they make a long turn. In terms of skiing velocity, it is needed to reduce friction on snow through the edging and pivoting of the radius or turn according to curvature and controlling ski pressure. Regarding a lower limb joint angle, it is important to make an up move by increasing ankle and knee angles instead of keeping the upper body straight during an up motion.

• Korean Journal of Applied Biomechanics
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• v.16 no.2
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• pp.65-73
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• 2006

The aim of this study was to find out the differences of Kinematics factors from touching down the vaulting board to landing when techniques of 1/1Turn and Tucked were performed on the old vaulting horse and on the new vaulting table. Three national representative men gymnasts were sampled for this study. Three dimension motion analyses by means of six Sony PD-150 video cameras with the velocity of 60 fps were used As a result of analyzing the kinematic data from two kind of vaulting table, the following conclusions were made. 1. The performing time from taking off the vaulting horse to landing(phase 4) in the 1/1 Turn technique on the new vaulting table was significantly longer than that of the old vaulting horse, while the time from contacting to taking off the vaulting horse on the new vaulting table was shorter than that of the old vaulting horse in both and the Tucked techniques. 2. The vertical release COG velocity was faster on the new vaulting table compare to the old vaulting horse in the all kind technique. However the horizontal release COG velocity of the 1/1 Turn technique was faster a little in the old vaulting horse compare to the new vaulting table.

• Korean Journal of Applied Biomechanics
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• v.16 no.4
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• pp.135-145
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• 2006

The aim of this study was to find out the differences of biomechanical factors from touching down the vaulting board to landing when techniques of 1/1Turn, stretched, and Tucked were performed on the old vaulting horse and on the new vaulting table. Three national representative men gymnasts were sampled for this study. Three dimension motion analyses by means of six Sony PD-150 video cameras with the velocity of 60 fps were used. As a result of analyzing the kinetic data from two kind of vaulting table, the following conclusions were made. 1. There was not significant differences of angular momentum between the old and the new vaulting table in all three techniques except the phase of stepping on the vaulting board and contacting the vaulting horse in the Tucked technique. IN the two phases above, the angular momentum in the new vaulting table was greater than that of the old vaulting horse. 2. There were few significant differences between the old and the new vaulting horses in the horizontal and vertical reaction force according to techniques when stepping was performed. However, it appeared tendency that the horizontal and vertical reaction force in the new vaulting table was a little greater than that of the old vaulting horse when the 1/1Turn, the Stretched and the Tucked were performed.

• Korean Journal of Applied Biomechanics
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• v.18 no.4
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• pp.67-76
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• 2008

The purpose of this study was to analyze differences in kinematic variables for mogul short turn motion between superior and inferior group, so that it can explore more effective mogul short turn motions. To meet the goals, this study selected total 10 ski players who would participate in mogul short turn event of the National Technical Ski Championship 2007, so that it could analyze kinematic variables by way of 3D motion analysis using DLT method. As a result, this study came to the following conclusions; For total and phase-specific duration, it was found that superior group took shorter time than inferior group. Superior group's Center of Mass was stands for more high value in up-down movement skill than inferior group. However right-left movement scale was less than them. In this reason, superior group was made a straight descent at the same time made a fast front-rear velocity. In the part of up-down movement velocity show that move slowly in the drop-in phase while increased in the bump-up phase. It is show that superior group was less tinny than inferior group include joint angle and knee joint angle. However leaning angle of trunk and the body inclination angle were more high figured than inferior group. Leaning angle of lower limbs also showed high figure at the center mogul. Lastly, In the part of body torsion angle show that superior group was high figure direction of right turn in the drop-in phase while in bump-up phase, made a high figure direction of left turn.