• Proceedings of the KSME Conference
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• 2001.06c
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• pp.128-133
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• 2001

For the Z-level machining, a tool-path linking procedure is presented. The linking problem is approached from the technological requirements, such as considering the machining constraints among the tool-path-elements, minimizing the tool-path length and reflecting the oneway/zigzag linking option. To simplify the linking problem, we develop a data structure, called a TPE-net, providing information on the machining constraints among the tool-path-elements. By making use of the TPE-net, the tool-path linking problem becomes a touring problem so that every node has been traversed.

• Journal of Dental Rehabilitation and Applied Science
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• v.28 no.3
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• pp.245-252
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• 2012

The purpose of this study was to evaluate the influence of glide path on canal centering ratio after instrumentation with different single file systems; WaveOne and Reciproc. Reciproc R25 (VDW), WaveOne Primary (Dentsply Maillefer) and PathFile #13, 16, 19 (Dentsply Maillefer) were used in this study. In no glide path groups, Reciproc files and WaveOne files used for canal preparation without glide path. In glide path groups, the PathFile were used before canal preparation. Methylene blue dye was introduced into the canal to obtain a clear pre-instrumentation image. Pre-instrumentation images and post-instrumentation images were scanned using Epson Perfection V700 Photo scanner (Epson, Nagano, Japan). Transparencies of post-instrumentation images were changed and superimposed on pre-instrumentation images using Adobe Photoshop CS 3 (Adobe Systems Incorporated, San Jose, CA, USA). The centering ratio was calculated for each instrumented canal using the following formula: CR=|X1-X2|/Y. It was statistically analyzed using two-way ANOVA at 95% confidential level. The centering ratio in glide path groups were significant less than it in no glide path groups at 3, 4, 5 and 6 mm level. Except 1 and 6 mm level, WaveOne groups had significant less centering ration than Reciproc groups. At 6 mm level, there was no significant difference between WaveOne and Reciproc. In the limitation of this study, creation of a previous glide path before reciprocating motion instrumentation in curved canal appears to be appropriate and WaveOne system can be used for preparation of curved canal without severe aberrations.

• Journal of the Korean Society of Safety
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• v.30 no.6
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• pp.139-147
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• 2015

This study deals with actual commuting distance and influence of risk factors depending on commuting distance and mode in order to reestablish actual commuting zone of primary school students. Data mining analysis(CHAID) was applied for this reestablishment using survey results from 6,927 primary school students in Seoul Metro. Six risk factors; convenience level of commuting path condition, convenience level of road crossing condition, vehicle speed on commuting path, segregation level between commuter and vehicle, congestion level of commuting path, and public security level and two mode; walking and cycle are considered in the analysis. As the results of CHAID analysis, commuting distance was divided into four zones; Internal Zone(0.491km under), External Zone(0.492 ~ 1.492km, 1.493 ~ 2.699km), Commutable Zone(2.70km over), and awareness level on safety is declined as commuting distance is increased. The risk factor affecting on safety is recognized differently by students depending on commuting distance and mode. For students commuting by walking, vehicle speed on commuting path and convenience level of commuting path condition are recognized as the prime risk factor within Internal Zone and Commutable Zone, respectively. For students commuting by cycle, convenience level of road crossing condition and vehicle speed on commuting path are recognized as the prime risk factor within Commutable Zone. Analysis results show that improved plan and program for commuting path for primary school students are required considering actual commuting distance and method.

• Journal of KIISE
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• v.42 no.1
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• pp.86-92
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• 2015

A level set tree provides a useful representation of a multidimensional density function. Visualizing the data structure as a tree offers many advantages for data analysis and clustering. In this paper, we present a level set tree estimation algorithm for use with a set of data points. The proposed algorithm creates a level set tree from a family of level sets estimated over a whole range of levels from zero to infinity. Instead of estimating density function then thresholding, we directly estimate the density level sets using one-class support vector machines (OC-SVMs). The level set estimation is facilitated by the OC-SVM solution path algorithm. We demonstrate the proposed level set tree algorithm on benchmark data sets.

• Journal of the Korean Data and Information Science Society
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• v.18 no.4
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• pp.985-994
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• 2007

We note that the time of adolescents is very important time for obtaining informations about their jobs, exploring and making appropriate their career decision. In order to understand the career decision level of adolescents, we needed a study on effects of personal variables and family variables affecting the career decision level. For this, we provide direct, indirect and total effects of family variables and personal variables on the career decision level using the path analysis. Therefore, in this study, we give the real usefulness for making a different diagnosis and strategy solving some problems of career decision level.

• Proceedings of the Korea Electromagnetic Engineering Society Conference
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• 2002.11a
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• pp.127-131
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• 2002

This paper presents the a measured path-loss characteristics in urban line-of-sight(LOS) and non line-of-sight(NLOS) environments for 3.4, 5.3, and 6.4 ㎓ band signals. A two-ray model is applied to analyse the path-loss characteristics in LOS areas. In LOS areas, an empirical break point, whose distance is shorter than a theorical break point, is founded. Further, a sudden power level drop occurs at a transition point from LOS region to NLOS area and different path-loss exponents are occured various cases. The power level drop due to comer loss and path-loss exponents both increase as the distance between the transmitter and the corner increases.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2013.04a
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• pp.476-481
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• 2013

Transfer path analysis(TPA) and operational deflection shape(ODS) have been widely utilized to analyze the characteristics of noise. TPA enables to decompose a noise into air-borne and structure-borne noises then estimate the path contribution of noise. ODS enables to analyze a moving shape and direction of interest components at a particular frequency. In this paper, TPA and ODS are applied to transfer paths of air-conditioner booming noise in a vehicle to reduce noise level, then a fixture is mounted it's path for distributing the high portion path contribution to the low portion path contribution. Through this experiment, the reduction of sound pressure level in air-conditioner booming noise is observed. Thereafter, TPA is again employed to verify the results of contribution.

• Magazine of the Korean Society of Agricultural Engineers
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• v.40 no.1
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• pp.106-117
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• 1998

The nature of stress-path dependency, the principle that governs deformations in granular soil, and the use of Lade's double work-hardening model for predicting soil response for a variety of stress-paths have been investigated, and are examined The test results and the analyses presented show that under some conditions granular soils exhibit stress-path dependent behavior. For stress-paths involving unloading or reloading, the stress-path with the higher average stress level produces the larger strains, whereas all stress-paths having the same intial states of stress, and involving only primary loading conditions, produce strains of similar magnitudes. Experimental evidence indicates that the stress- path dependent response obtained from the double work-hardening model is also observed for real soils. It is concluded that the influence of stress history on the friction angle is negligible and the strains increment direction is uniquely determined from the state of stress but is not perpendicular to the yield surface. The strains calculated from Lade's double work-hardening model are in reasonable agreement with those measured.

• Magazine of the Korean Society of Agricultural Engineers
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• v.21 no.1
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• pp.78-85
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• 1979

In order to obtain the basic data for designing optimum flat plate solar air heaters, which can be operated with relatively low temperature for drying farm products, 8 different treatment of solar air heaters were devised and tested for their heating performances and efficiencies. The results were analised and summarized as follows. 1. The primary factors, structure of air path (C), black coating materials (A) and bottom coating methods (B) showed very high significant effect of far above 1% level. With respect to the mutual multiplying effect of secondary factors, 1% level of significance was found with coating materials and methods (AB), and 5% level of significance was found with coating materials and air path structure (AC). 2. The heating performance of the air heaters with winding air path showed about twice those with straight air path. 3. The Korean black ink which is less expensive than dim oil paint showed 3-4% better heating efficiencies as the black coating material of flat plate solar air heaters. 4. The heating efficiencies of the solar air heaters whose bottoms were not black coated were 2-3% higher than those with black coated bottoms. 5. The highest heating efficiency of solar air heater among 8 different treatment was found in the plot of Korean black ink-bottom not coated-winding air path showing 29.0-34.5%

• Journal of Auto-vehicle Safety Association
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• v.11 no.2
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• pp.17-22
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• 2019

This paper describes the tracking algorithm performance evaluation for autonomous vehicle using a safety envelope based path. As the level of autonomous vehicle technologies evolves along with the development of relevant supporting modules including sensors, more advanced methodologies for path generation and tracking are needed. A safety envelope zone, designated as the obstacle free regions between the roadway edges, would be introduced and refined for further application with more detailed specifications. In this paper, the performance of the path tracking algorithm based on the generated path would be evaluated under safety envelop environment. In this process, static obstacle map for safety envelope was created using Lidar based vehicle information such as current vehicle location, speed and yaw rate that were collected under various driving setups at Seoul National University roadways. A level of safety was evaluated through CarSim simulation based on paths generated with two different references: a safety envelope based path and a GPS data based one. A better performance was observed for tracking with the safety envelop based path than that with the GPS based one.