• Journal of the Korea Institute of Military Science and Technology
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• v.21 no.4
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• pp.413-421
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• 2018

The pyroshocks can cause failure of electronics devices and structures. Metal-metal impact methods are utilized to simulate mechanical pyroshock, and to adjust the knee frquency of the SRS(Shock Response Spectrum) through resonant structures. In this paper, the major parameters of pyroshock simulation device which affect the SRS were examined. Through the Hertzian contact law and the modal characteristics of the resonant bar, it was found that the SRS is affected by the length and mass of a bar and various impact conditions such as velocity and mass of impactor. The characteristics due to the geometric parameters of a resonant bar was analyzed by performing FEA and also the resonant bar was designed and fabricated. Through the pyroshock simulation test, the characteristics of SRS due to the variation of impact parameters were examined.

• The KSFM Journal of Fluid Machinery
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• v.13 no.3
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• pp.43-48
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• 2010

In this study rotordynamic characteristics of an air turbo-compressor (ATC) used in oxygen plant are analyzed and its operating-speed balancing is performed to solve the vibration trouble caused by rotor unbalance. Three dimensional model of the ATC rotor is completed and then analytical FE (finite element) model, which is verified by experimental modal testing, is developed. A rotordynamic analysis includes the critical map, Campbell diagram, and unbalance response, especially considering the pedestal housings supporting tilting pad bearings. A test run of operating-speed, using tilting-pad bearing of actual use, showed that the vibration level increased very sharply as approaching the rated speed. The operating-speed balancing specified by API 684 was carried out by using influence coefficient method. The results showed that the vibrations at the bearing pedestal housings represented good levels of 0.1 mm/s. From the test run and operating-speed balancing, the analytical results, that is, critical speeds are in good agreement with the test results and unbalance responses introducing the correction masses are similar to the as-is test responses in its aspect.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.11 no.1
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• pp.76-81
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• 2012

Ultrasonic metal welding is one of the welding methods which welds metal by applying high frequency vibrational energy into specific area at constant pressure, avaliable in room temperature and low temperature. Ultrasonic metal welder is consisted of power supply, transducer, booster, and horn. Precise designing is required since each parts' shape, length and mass can affect driving frequency and vibration mode. This paper focused to horn design, its length L was set to 62mm by calculating vibration equation. By performing modal analysis with various shape variable b times integer, when length of b is 30mm the output was 39,599Hz at 10th mode. Also by performing harmonic response analysis, the frequency response result was 39,533Hz, which was similar to modal analysis result. In order to observe the designed horn's performance, about 4,000 voltage data was obtained from a light sensor and was analyzed by FFT analysis using Origin Tool. The result RMS amplitude was approximately 8.5${\mu}m$ at 40,000Hz, and maximum amplitude was 12.3${\mu}m$. Therefore, it was verified that the ultrasonic metal welding horn was optimally designed.

• Proceedings of the KSR Conference
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• 2010.06a
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• pp.2303-2308
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• 2010

We studied the cost-volume supply characteristic of public transportation systems focused on Bi-modal Tram in the main cities to analyze the applicability and status for the new transit system Bi-modal Tram as public transportation system. The operation cost considering the characteristic of vehicle, facilities, operation and average cost for respective public transportation system and the time cost considering the travel and transfer time are defined to the social cost, and the cost-volume supply curve is based on this social cost. The cost-volume supply characteristic between public transportation modes in the city is determined on the basis of cost-volume supply curve. Through the comparison between cost-volume supply characteristic of main transportation systems, it is analyzed about the relation between public transportation systems in the city and the characteristic for proper service provision. The application of Bi-modal Tram in the city is concluded that it is effective to reduce the social cost on the existing public transportation system.

• Journal of ILASS-Korea
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• v.20 no.1
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• pp.14-19
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• 2015

Recently, R&D demand for environmental friendly vehicle has rapidly increased due to its global environmental issues such as global warming, energy and economic crisis. Under this situation, the most realistic alternative way for environmental friendly vehicle is a clean diesel vehicle. The common-rail fuel injection system, as key technology of clean diesel vehicle, consists of a high pressure pump, common-rail, high pressure fuel line and electronic control injector. In common-rail high-pressure fuel injection system, high pressure wave of injection system and geometry of injector elements have a major effects on high-pressure fuel spray. Therefore, in this study, the numerical model was developed for analysis about the common-rail fuel pressure pulsation by using AMESim code. We could secure stability of common-rail high-pressure fuel injection system through optimal design of fuel line.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.26 no.4
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• pp.375-382
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• 2016

The mechanical property of a carbon-fiber-reinforced plastic (CFRP) is subjected to two elements, carbon fiber and polymer resin, in a first step and the selection of multi-layered structure is second one. Many combination of fabric layers, i.e. plainweave, twillweave, can be derived for candidates of test specimen used for a basic mechanical components so that a reliable identification of dynamic nature of possible multi-layered structures are essential during the development of CFRP based component system. In this paper, three kinds of multi-layered structure specimens were prepared and the dynamic characteristics of service specimens were conducted through classical modal test process with impact hammer. In addition, the design sensitivity analysis based on transmissibility function was applied for the measured response data so that the response sensitivity for each resonance frequency were compared for three CFRP test specimens. Finally, the evaluation of CFRP specimen over different multi-layered fabric structures are commented from the experimental consequences.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.32 no.11
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• pp.970-977
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• 2008

This paper deals with the dynamic characteristics of the shaft with impeller model which is the most important part in developing the resin mixing machine. Through reverse engineering, it is possible to make the shaft with impeller geometry model which is necessary vibration characteristic analysis by commercial impeller. The natural frequency analysis and structural analysis using finite element analysis software are performed on the imported commercial shaft with impeller model. The most important fundamental natural frequency of the shaft with impeller model is around 14.5 Hz, which well agrees with modal testing. The most effective design variables were extracted by ANOM(analysis of means) and pareto chart. This paper presents approximation 2nd order polynomial as design variables using RSM(response surface methodology). Generally, RSM take 2 or 3 design variables, but this method uses 5 design variables with table of mixed orthogonal array. Further more, the analyzed result of the commercial shaft with impeller is to be utilized for the structural design of resin chock mixing machine.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2002.05a
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• pp.373-377
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• 2002

In this study, we suggested a slim-type actuator that can be controlled in radial direction for compensating coma aberration in high-capacity optical storage devices. To deal successfully with narrow space in slim-type optical pick-up for notebook pc device, additional yokes for tilting motion are integrated into main yoke of the actuator. And the location of tilting coils is determined for mass-b3lancing effect to achieve optimal configuration for high driving sensitivity. We also suggested new concept of lens holder to guarantee excellent stability of control system by enhancing the gain margin at secondary resonant frequency. The concept was realized by forming damping sections in the lens holder, which prevent vibrational energy from transferring to lens. An exclusive measurement system was newly developed for fast and precise measurement of dynamic characteristics of actuators and utilized for the practical use. We hope to make good use of this system also in time to come.

• Annual Conference on Human and Language Technology
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• 2009.10a
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• pp.19-24
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• 2009

의사소통에서 대화자 간 감정의 이해는 메시지의 내용만큼이나 중요하다. 비언어적 요소에 의해 감정에 관한 더 많은 정보가 전달되고 있기는 하지만, 텍스트에도 화자의 감정을 나타내는 언어적 표지가 다양하고 풍부하게 녹아 들어 있다. 본 연구의 목적은 인간언어공학에 활용할 수 있는 감정 온톨로지를 설계하는 데 있다. 텍스트 기반 감정 처리 분야의 선행 연구가 감정을 분류하고, 각 감정의 서술적 어휘 목록을 작성하고, 이를 텍스트에서 검색함으로써, 추출된 감정의 정확도가 높지 않았다. 이에 비해, 본 연구에서 제안하는 감정 온톨로지는 다음과 같은 장점을 갖는다. 첫째, 감정 표현의 범주를 기술 대상(언어적 vs. 비언어적)과 방식(표현적, 서술적, 도상적)으로 분류하고, 이질적 특성을 갖는 6개 범주 간 상호 대응관계를 설정함으로써, 멀티모달 환경에 적용할 수 있다. 둘째, 세분화된 감정을 분류할 수 있되, 감정 간 차별성을 가질 수 있도록 24개의 감정 명세를 선별하고, 더 섬세하게 감정을 분류할 수 있는 속성으로 강도와 극성을 설정하였다. 셋째, 텍스트에 나타난 감정 표현을 명시적으로 구분할 수 있도록, 경험자 기술 대상과 방식 언어적 자질에 관한 속성을 도입하였다. 이때 본 연구에서 제안하는 감정 온톨로지가 한국어 처리에 국한되지 않고, 다국어 처리에 활용할 수 있도록 확장성을 고려했다.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.14 no.3
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• pp.991-996
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• 2013

In this paper, the ultrasonic horn having the natural frequency with 60 [kHz] for the dissimilar material bonding of the glass and solder tried to be designed. The ultrasonic horn was designed through the relational formula including the aspect ratio of the input terminal and output terminal, length of the ultrasonic horn. The modal analysis was performed for the propriety analysis of the designed horn. The parameters and response was set through the basic experiment. The dissimilar material bonding strength analysis using the ultrasonic transducer was done. The optimal process parameters having maximum bonding strength was derived.