• Proceedings of the Korean Society of Precision Engineering Conference
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• 2001.04a
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• pp.895-898
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• 2001

This paper presents an optimization cutting speed(OCS) program developed to improve the machining precision and tool life in high speed machining using ball end milling. This program optimized the cutting speed that is changing at any time in free surface machining of an automobile part like a connecting load die. The technique of optimization cutting speed makes the CAD/CAM-generated NC code go through a reverse post process, conducts cutting simulation, and obtain the effective tool diameter of the ball end milling. Then it changes the spindle revolution to within the range of critical cutting speed fit for the material of the workpieces depending upon the effective tool diameter. In this study, the machining precision and tool life were compared for the two connecting load dies processed using the general cutting method and the proposed optimization cutting speed technique, respectively.

• Korean Journal of Computational Design and Engineering
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• v.5 no.2
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• pp.168-174
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• 2000

A biarc is a curve connecting two circular arcs with the constraints of tangent continuity so that it can represent the free form currie approximately connecting several biarcs with the tangent continuity. Since a biarc consists of circular arcs, the offset curve of the curve represented by biarcs can be easily obtained. Besides. if the tool path is represented by biarcs, the efficiency of machining is improved and the amount of data is decreased. When approximating a curve with biarcs, the location of the point where two circular arcs meet each other plays an important part in determining the shape of a biarc. In this thesis, the optimum point where two circular arcs meet is calculated using the tangent information of the curve to approximate so that it takes less calculation time to approximate due to the decrease of the number of iterations.

• Journal of Power System Engineering
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• v.13 no.5
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• pp.40-45
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• 2009

This article deals with the transient analysis using multi-flexible body dynamics of a trailer vehicle, which is passing a bump on the flat road. In order to investigate the transient dynamic behavior of the trailer, we developed an equivalent finite element model for the trailer and a vehicle dynamic model for the truck using multi-body dynamics. The driving condition considered here is set as the trailer vehicle passes a bump on the flat road in 7km/h. And we investigate the time histories of vertical load and deflections on connecting points between the trailer and truck during the vehicle passes a bump. Due to the dynamic load resulted from the driving condition, additional stress concentrations are found in the trailer and the suspension connecting points between the trailer and rear axles along with kingpin.

• Journal of the Korea Computer Industry Society
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• v.10 no.3
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• pp.79-86
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• 2009

This paper proposes a mechanism for prompt and efficient construction of sensor network connecting sensor nodes and base stations using limited length edges minimum spanning tree. This mechanism can rapidly build a connecting tree which may be used in routing of sensor network. In an experiment for 2000 input terminal nodes, this mechanism can curtail 94.7% construction time comparing with the method by naive minimum spanning tree without tree length overheads. This shows the proposed mechanism can apply well to the application of swift construction of a sensor network.

• Journal of Applied Reliability
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• v.5 no.4
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• pp.405-412
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• 2005

In this paper, we verified the failure mechanism of the discolored masking tape wrapped around the wire and studied an improved case study as well. Masking tapes are poly(Vinylchloride-co-Methyl methacrylate) (PVC) and the wire connecting with indoor/outdoor components of the air conditioner is chloroprene(CR). The masking tape under. the ultraviolet ray was accelerated to discolor fivefold. The results determined reveal the discoloration of masking tapes as an elution of the additives, dephenyl Amine series antioxidants, in the connecting wire. When changed dephenyl Amine series to phenol series, we found that the degree of discoloration was dramatically decreased. Due to stink of Thiourea and Thiuram monosulfide, as accelerators in CR wire, we controlled the vulcanization temperature and time without using these accelerators and could get the wire not to smell bad with the equal mechanical properties.

• Journal of Educational Research in Mathematics
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• v.16 no.1
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• pp.59-78
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• 2006

As a theoretical background for this research, the literatures which focus on the rationale of teaching and learning of connecting with mathematics and science in calculus were investigated. And teaching and learning material of connecting with mathematics and science in calculus was developed. And then, based on the case study using this material, the research questions were analyzed in depth. Students could understand mean-velocity, instant-velocity, and acceleration in the experimenting process of constant acceleration movement. Also Students could understand fundamental ideas that instant-velocity means slope of the tangent line at one point on the time-displacement graph and rate of distance change means rate of area change under a time-velocity graph.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.51 no.7
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• pp.349-361
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• 2002

Occasionally, equipment in a distribution system fails due to damage from weather, vandalism, or other causes. Failures and unexpected events do not always occur as and where expected. Therefore, a good contingency plan, multi-zone or otherwise, provides flexibility by locating switches at various strategic locations so that parts of a feeder can be picked up in the event of line outages at various places. It is possible to create feeder system layout that achieve remarkable contingency support economics, even as their normal peak loading levels approach thermal capacity, by utilizing six, seven, or even nine switchable zones per feeder. But many switchable zones per feeder are of questionable practicality and effectiveness, because of the complexity and time required for the switching operation. In practice, a zonal scheme with between three and four zones will usually provide complete contingency backup for all feeders. Line switches have both capital and maintenance costs, the planning for multi-zonal schemes is considerably more difficult than or loop or single-zone systems, and the required switching operations required during contingencies take more time. But multi-zonal schemes are used because these costs come to far less than the cost of additional capacity required for loop or single-zone. In this paper, we present the optimal number of switchable zones per feeder in Kora distribution system.

• Journal of the Korean Society of Radiology
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• v.14 no.5
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• pp.597-602
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• 2020

The study was conducted to improve the efficiency of the test and to reduce the exposure dose of patients and operators by analyzing the difference in the moving speed of Lipiodol according to the temperature during lymphography. The device for injecting Lipiodol at a constant pressure was self-made, and after inserting Lipiodol into the Connecting Tube, the moving speed of the contrast agent was photographed at temperatures of 26℃, 36℃, and 46℃ using a heat transfer device. Lipiodol movement time from the Support Catheter to 20cm was measured and analyzed, and statistical significance was confirmed. In the 46℃ environment, the average moving time was 11 seconds, at 36℃ the average was 13 seconds, and at 26℃ the average was 17 seconds. Lipiodol showed a significant difference in moving time with increasing temperature (p<.001), and it was confirmed that the higher the temperature, the faster the moving speed. In the case of lymphangiography, when heated to a certain temperature (46 degrees) rather than injecting Lipiodol at room temperature, the injection speed can be increased and the speed of movement in the lymphatic vessel can be improved.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2002.11a
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• pp.770-774
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• 2002

Recently, most of the embedded system have the function of multimedia information processing and network connecting. This make the overall system more complicated and need a new approach. Moreover the embedded system must be real-time system, which are different with Linux is constructed and the kernel is redesigned on the strong-arm board in order to make the real-time embedded web-server system.

• Journal of the Korea Society for Simulation
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• v.5 no.1
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• pp.1-12
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• 1996

We propose a new approach to classifying a time series data into one of the autoregressive moving-average (ARMA) models. It is bases on two pattern recognition concepts for solving time series identification. The one is an extended sample autocorrelation function (ESACF). The other is a neural network-driven decision tree classifier(NNDTC) in which two pattern recognition techniques are tightly coupled : neural network and decision tree classfier. NNDTc consists of a set of nodes at which neural network-driven decision making is made whether the connecting subtrees should be pruned or not. Therefore, time series identification problem can be stated as solving a set of local decisions at nodes. The decision values of the nodes are provided by neural network functions attached to the corresponding nodes. Experimental results with a set of test data and real time series data show that the proposed approach can efficiently identify the time seires patterns with high precision compared to the previous approaches.