• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.18 no.2
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• pp.238-246
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• 2008

This case study refers to turbine-generator with retrofitted turbine rotor. Vibration problem occurring after the retrofit was mainly due to high vibration from exciter side. However, repeated test run and operation during scheduled maintenance caused high vibration from generator bearing, and post-overhaul test run before turbine vibration correction caused oil whip on the bearing. This case study shows how to analyze vibration condition of high turbine generator vibration detected during the post-overhaul test run and vibration condition of offline and online data to reflect it on establishing maintenance schedule and overhaul correction procedure. Vibration data could be acquired during steady load operation or even with varying speed and load. Each data is important for machinery condition evaluation. This case study shows that the vibration data during extreme condition is the key factor in analysis, which helps to find the machinery problem.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.14 no.6
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• pp.2979-2984
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• 2013

This paper proposes a modeling and controller design method of Flywheel Energy Storage System(FESS) for solving the unstable operation problem in hybrid generation system with wind turbine and diesel generator applied in island area. FESS is considered as a permanent magnetic synchronous machine connected to flywheel because of its efficiency. The controller of FESS is composed of AC/DC/AC back-to-back converter. The AC/DC converter is designed to charge/discharge according to the frequency variation and the DC/AC converter to operate to keep the DC bus voltage constant. The proposed modeling and controller design method of FESS was applied to hybrid generation system with wind turbine and diesel generator. The unstable operation problem owing to wind variations was solved through simulation results.

• Journal of Korea Game Society
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• v.12 no.4
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• pp.23-31
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• 2012

The collision processing is one of the essential factors to realize physical principles in the game, and it gives liveliness to the game. The collision processing requires a large amount of operations, and significantly affects the game performance. To address this problem, many studies have been conducted to reduce the operation volume, and the SAP algorithm is being widely used. However, its efficiency is low because it involves repetitive operations. In this study, a distance-based SAP algorithm was proposed to reduce the operation volume for the collision processing and address the problem of the SAP algorithm. A test was conducted to measure the FPS using the simulation program, which was developed with the proposed algorithm. The FPS was 2-33 times higher with the proposed algorithm, which indicated that the efficiency of the collision processing was improved.

• THE INTERNATIONAL COMMERCE & LAW REVIEW
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• v.70
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• pp.81-107
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• 2016

Purpose : The purpose of this study is to find that Factors in the practical application of LISMB(Logistics Information System Practice Based) on S.P(Smartphone)' Characters. and take in the whole situation of LISMB on S.P' Characters by this research and it is clear from the findings that LISMB on S.P' Characters situations and distinctiveness. Research design, data, methodology : Research model and hypotheses have been developed based on literature review and working-level interview The collected data were analysed with structural equation modeling, examining the hypothesized relationships and mediating effect. Result : The results of research are as follows, First, LISMB on S.P' Characters has a positive effect on a precariousness of operation management. but That has no effect on a precariousness of general management. Second, Consign management and User non-cooperation has a mediating effect on relationships between LISMB on S.P' Characters and general management. Third, Old version system, User non-cooperation and Unskilled in equipment new system has a partly mediating effect on relationships between LISMB on S.P' Characters and operation management. Conclusion : Smart-phon Prevalence rates keeps increasing. Nevertheless, LISMB on S.P' Characters may no be used in Container transportation market. This problem are being blamed for hampering corporate activities and harbor logistics industry development. so we need new way to solve that problem.

• Journal of the Korea Safety Management & Science
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• v.10 no.4
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• pp.135-143
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• 2008

Recently as the testing of fire detector used the testing device for fire detector, there are something the matter in the perception function loss of fire detector, structure and form of the testing device for fire detector. The problem at oxidation of emitting smoke ashes hazardous article part and so on that checking person absorbs be. In this paper the problem or the conventional the examination equipment of fire detectors is analysed and researched. To solve these problems after the theoretical study and design and paint drawing of equipment the prototype of composite examination equipment of fire detectors was made. After compared with the conventional, part that improve of composite examination equipment of fire detectors are verified through the examination. In the future it will be useful the operation state and correct operation time of the fire detectors are measured after the research about the quality of the material and transparency of bellows cover is done.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.14 no.1_2
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• pp.40-53
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• 1992

This sutdy aimed at examining the effect of lingual frenectomy on phonation & tongue movement. Almost the patient visiting to department of oral & maxillofacial surgery for the treatment of tongue tie always complain the speech problem. Many operation was performed according to this problem. But the objective evaluation of the speech change have been deficient. The experimental group was 25 adult males. Fourteen Korean consonants & after Korean vowels was combined and seventy sound was made for speech analysis. Before & after lingual frenectomy, the speech of the above mentioned group was recorded and then analysed by the Speech Workstation computer software. And before & after operation, the lingual frenum & tongue protrusion amount vas measured. The results were as follows : 1. The pre-operative length of lingual frenum was inverse proportion with the pre-operative length of the protrusive tongue. 2. The average difference between pre & post-operative length of the protrusive tongue was about 23 mm. 3. In the comparison of consonant continuing time change, fricative consonant(r, s, h) was increased post-operatively. 4. In the comparison of the vowel frequency formant change, the "i"and "u" sound vas reliably changed. 5. There was no reliable speech changes on the other sounds.

• The KIPS Transactions:PartA
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• v.16A no.5
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• pp.319-326
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• 2009

Since string operations were applied to computational biology area, various data structures and algorithms for computing efficient string operations have been studied. The longest common substring problem is an operation to find the longest matching substring in more than two strings, and maximal repeat of string problem is an operation to find substrings repeated more than once in the given string. These operations are importantly used in the string processing area such as pattern matching and likelihood measurement. In this paper, we present algorithms to compute the longest common substring of two strings and to find the maximal repeat of string using three-dimensional $n{\times}n{\times}n$ processors on RMESH(Reconfigurable MESH). Our algorithms have O(1) time complexity.

• Journal of Power Electronics
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• v.18 no.1
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• pp.45-55
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• 2018

It is usually difficult for dual-active-bridge (DAB) dc-dc converters to operate efficiently at light loads. This paper presents an in-depth analysis of a DAB with triple-phase-shift (TPS) control under the light load condition to overcome this problem. A kind of operating mode which is suitable for light load operation is analyzed in this paper. First, an analysis of the zero-voltage-switching (ZVS) constraints for the DAB converter has been carried out and a reasonable dead-band setting method has been proposed. Secondly, the basic operating characteristics of the converter are analyzed. Third, under the condition of satisfying the ZVS constraints, both the reactive power and the root mean square (RMS) value of the current are simultaneously minimized and a particle swarm optimization (PSO) algorithm is employed to analyze and solve this optimization problem. Lastly, both simulations and experiments are carried out to verify the effectiveness of the proposed method. The experimental results show that the converter can effectively achieve ZVS and improved efficiency.

• The Transactions of the Korean Institute of Power Electronics
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• v.26 no.2
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• pp.96-105
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• 2021

Large-scale power converters consist of series or parallel module combinations. In these modular converter systems, the interleaving technique can be applied to improve capacitor reliability by reducing the ripple of the I/O current in which each module operates as a phase difference. However, when applying the interleaving technique for conventional three-level boost converters, the short-circuit period of the converter can be an obstacle. Such problem is caused by the absence of a low-level inductor of the conventional three-level boost converter. To solve this problem, a three-level boost converter with a low-level inductor is proposed and analyzed to enable interleaved operation. In the proposed circuit, the current ripple of the output capacitor depends on the neutral point connections between the modules. In this study, the ripple current is analyzed by the neutral point connections of the three-level boost converter that has a low-level inductor, and the effectiveness of the proposed circuit is proven by simulation and experiment.

• Journal of the Korean School Mathematics Society
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• v.18 no.3
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• pp.241-258
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• 2015

The purpose of this paper is to examine the students' mathematics problem solving process in the intuitive stages. For this, researcher developed the questionnaire which consisted of problems in relation to intuitive and algorithmic problem solving. 73 fifth grade and 66 sixth grade elementary students participated in this study. I got the conclusion as follows: Elementary students' intuitive problem solving ability is very low. The rate of algorithmic problem solving is higher than that of intuitive problem solving in number and operation areas. The rate of intuitive problem solving is higher in figure and measurement areas. Students inclined to solve the problem intuitively in that case there is no clue for algorithmic solution. So, I suggest the development of problems which can be solved in the intuitive stage and the preparation of the methods to experience the insight and intuition.