• Proceedings of the KSR Conference
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• 2002.10a
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• pp.516-521
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• 2002

This paper was reviewed technical items of catenary system for electrification of Gyeongbu(Dongdaegu∼Busan) and Honam(Daejeon∼Mokpo) conventional Railways. The lines have adopted new technical items in order to connect to Gyeongbu high speed railway. We can use the technology and experience of Gyeongbu and Honam lines to a new catenary system design up-graded for speed-up of conventional lines and new lines construction.

• Journal of the Korean Society for Railway
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• v.13 no.4
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• pp.376-381
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• 2010

In this study, field measurements on KTX, Nuriro and TTX train have been conducted at Kyeongbu and Honam line to predict the wind gust under train at the speed-up of major conventional railway lines using Kiel-probe array and multi-channel pressure scanning system. The results show that the average wind velocity during train passage normalized by train speed is independent to train speed, thus the wind gust for a given train type at the speed-up condition could be predicted. The relationship between the shape of underbody and the characteristics of the underbody wind gust has been discussed.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.15 no.2
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• pp.111-117
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• 2016

The cutting performance of a developed small-angle spindle tool was investigated with Al6061 using a TiAlN coated high-speed steel end mill. Up-cut and down-cut processes in a milling machine were carried out at the range of 1000-4000 rpm for spindle speed and 50-300 mm/min for feed rate. As a result, the highest cutting force in the Fx direction was obtained from the up-cut process when the spindle speed was 1000 rpm and the feed rate was 100 mm/min. In the Fy direction, the highest cutting force appeared in the up-cut process at a feed rate of 250 mm/min at the same spindle speed. Conversely, the lowest cutting force came out in the up-cut process at a spindle speed of 4000 rpm and a feed rate of 50 mm/min. As for surface finish, the finest surface roughness was obtained as Ra 0.7642 um at a spindle speed of 4000 rpm and a feed rate of 50 mm/min. Consequently, given the cutting performance of the developed small-angle spindle tool, we conclude that its use in industrial practice is feasible.

• Journal of Computing Science and Engineering
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• v.1 no.2
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• pp.195-210
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• 2007

Dwarf is a highly compressed structure, which compresses the cube by eliminating the semantic redundancies while computing a data cube. Although it has high compression ratio, Dwarf is slower in querying and more difficult in updating due to its structure characteristics. We all know that the original intention of data cube is to speed up the query performance, so we propose two novel clustering methods for query optimization: the recursion clustering method which clusters the nodes in a recursive manner to speed up point queries and the hierarchical clustering method which clusters the nodes of the same dimension to speed up range queries. To facilitate the implementation, we design a partition strategy and a logical clustering mechanism. Experimental results show our methods can effectively improve the query performance on data cubes, and the recursion clustering method is suitable for both point queries and range queries.

• Journal of the Korean Society for Precision Engineering
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• v.21 no.7
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• pp.124-129
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• 2004

Recently, the demand for the optical cable is rapidly growing because the number of internee user increases and high speed internet data transmission is required. But the present optical cable winding systems has some serious problems such as pile-up and collapse of cable usually near the flange of the bobbin in the process of the cable winding. To reduce the pile-up collapse in a cable winding systems, a new guiding system is developed for a high-speed self-align cable winding. First of all, the winding mechanism was analyzed and synchronization logics for the motions of winding, traversing, and the guiding were created. A prototype cable winding systems was manufactured to validate the new guiding system and the suggested logic. Experiment results showed that the winding system with the developed guiding system outperformed the system without the guiding system in reducing pile-up and collapse in the high-speed winding.

• Proceedings of the Korean Society for Agricultural Machinery Conference
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• 1993.10a
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• pp.1053-1062
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• 1993

The effect of loading speed on soil failure was studied by using a high speed triaxial compression test. Tests were conducted at 0.35-6.2m/s loading speed to compress soil specimens of sandy loam at different moisture contents. The axial stress at fracture increased with increase in loading speed up to certain critical speeds, however they decreased as the speed up to certain critical speeds, however they decreased as the speed increased further. Experiments were also conducted in the field of sandy loam soil with the vibrating tillage tool. Tests were done at 0.33-0.85m/s tractor speed oscillating frequency 13.7hz and oscillating amplitude 59mm. The maximum oscillating velocity of tillage tool was 2.5m/s. It was observed that for the oscillating operation, initially draft slightly increased with increase in forward speed and then it decreased .For the non-oscillating operation, draft increased continuously with increase in forward speed. Approach of studying soil failure in the laboratory test can be related to the field experiments.

• Journal of the Korean Society for Precision Engineering
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• v.16 no.3 s.96
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• pp.18-24
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• 1999

ThisPaper investigates the feasibility of using acoustic emission signal analysis for the detection of built-up edge during machining. Experiments were conducted on a CNC-lathe using conventional carbide insert tools under various cutting conditions. The cutting forces were also measured for comparisons. Experimental evidence is presented which indicates that the presence of a built-up edge can significantly affect the generation of acoustic emission in metal cutting. It is shown that under conditions in which a built-up edge is generated, the variation of $AE_{rms}$ signal with cutting speed can be quite different from the generally accepted linear, monotonic increase as previously reported. The feasibility of utilizing $AE_{rms}$ in built-up edge sensing is suggested.

• Physical Therapy Korea
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• v.11 no.1
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• pp.1-17
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• 2004

The purposes of this study were to find correlations among Fugl-Meyer Assessment scale, gait speed, and Timed Up & Go test (TUG) and to predict gait ability from subscales of Fugl-Meyer Assessment scale. The study population consisted of 30 stroke patients referred to the Department of Rehabilitation Medicine in the Bundang Jaesang General Hospital. All subjects were ambulatory with or without an assistive device. All participants were assessed on Fugl-Meyer Assessment scale and gait speed (m/s), TUG (s). The data were analyzed using independent t-test, Pearson product moment correlation analysis and stepwise multiple regression. The results revealed that all items of Fugl-Meyer Assessment scale, except passive joint range of motion were significantly correlated with gait speed and TUG. In particular, sensation score, lower extremity motor and coordination score have a significant correlation with gait speed and TUG (p<.05). The sensation score and lower extremity motor score were important factors in comfortable gait and maximal gait speed. Their power of explanation regarding comfortable gait and maximal gait speed were 63.0% and 65.0%, respectively. The sensation score and lower extremity coordination score were important factors in TUG. Their power of explanation regarding TUG was 55.0%. These results showed that Fugl-Meyer Assessment scale is significantly correlated with gait speed and TUG. Therefore Fugl-Meyer Assessment scale is an appropriate assessment tool to predict gait ability of patients with stroke. Further study about gait speed and TUG by change of Fugl-Meyer Assessment score is needed using a longitudinal study design.

• Journal for History of Mathematics
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• v.15 no.3
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• pp.75-82
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• 2002

G$\ddot{o}$del's metamathematical program from Incompleteness to Speed-up theorems shows the necessity of ever higher systems beyond the fixed formal system and devises the relative consistency.

• The Transactions of the Korean Institute of Power Electronics
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• v.21 no.5
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• pp.411-417
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• 2016

Theoretical IPMSM control technique is complicated, and reliability is low because of the changing parameters. Further, in case of general look-up table designing method which obtains torque characteristics (according to current and speed) or torque characteristics (according to magnetic flux through the entire control region), obtaining a precise result can be difficult and has the disadvantage taking too much time to establish a current look-up table. In this paper, the new auto maximum torque point tracking (MTPT) algorithm that automatically finds the optimum stator d - q axis electric current reference through the entire speed region is devised; consequently, it could establish a 3D look-up table with torque characteristics according to current and speed. In case of using the devised auto MTPT algorithm, the result value detailed was obtained in comparison with the generalized look-up design technique, and checked to reduce the current look-up table establishment time.