• 한국정밀공학회지
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• 제13권4호
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• pp.53-60
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• 1996

In the conventional linear elasticity, sound speed is determined by only elastic modulus and density of the medium. In actual, however, sound speed depends on the stress and this dependency becomes nonlinear as the stress increases. These phenomena can be introducing nonlinear elastic modulus. In this paper, relationships between nonlinear elastic modulus up to 4th order and the internal status of materials are discussed through computer simulations and experiments. For the measurement of sound speed, a new type of measurement system using ultrasonic wave is proposed on the basis of ultrasonic pulse echo method which has been generally used in nondestructive ultrasonic test equipment. In order to confirm the stress dependency of sound speed, several experiments are carried out for alumina specimen.

• ETRI Journal
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• 제38권3호
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• pp.479-486
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• 2016

System-on-chip (SoC) designs have a number of flip-flops; the more flip-flops an SoC has, the longer the associated scan test application time will be. A scan shift operation accounts for a significant portion of a scan test application time. This paper presents physical-aware approaches for speeding up scan shift operations in SoCs. To improve the speed of a scan shift operation, we propose a layout-aware flip-flop insertion and scan shift operation-aware physical implementation procedure. The proposed combined method of insertion and procedure effectively improves the speed of a scan shift operation. Static timing analyses of state-of-the-art SoC designs show that the proposed approaches help increase the speeds of scan shift operations by up to 4.1 times that reached under a conventional method. The faster scan shift operation speeds help to shorten scan test application times, thus reducing test costs.

• 한국초전도저온공학회:학술대회논문집
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• 한국초전도저온공학회 2003년도 학술대회 논문집
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• pp.236-238
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• 2003

The speed-torque characteristics of the squirrel cage induction motor is determined by the rotor resistance. This paper presents the fabrication and test results of an HTS induction motor. Conventional end rings and short bars were replaced with HTS tapes in the rotor. Test result shows that the speeds of the HTS induction motor were the same with synchronous speed up to 10Nm.

• 한국자동차공학회논문집
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• 제4권5호
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• pp.90-99
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• 1996

To keep up with the regulation of OBD II(on board diagnostics II), many detection methods for engine misfire have been developed. Among them, the method of using the crankshaft speed fluctuation is the most noticeable in the point of view of lower cost and easier installation than any others. On the basis of the results obtained from the previous engine-dynamometer test, the integrating torque index (ITI) has been introduced. In this research, the instrumental and the interfacing systems to engine control unit(ECU) are developed for the vehicle test. Therefore, the vehicle and chassis-dynamometer test can be carried out in addition to the rough road test. From this test, the previousproposed method proved that it can be applied to the real vehicle.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2011년도 정기총회 및 추계학술대회 논문집
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• pp.761-767
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• 2011

Since the "Low Carbon, Green Growth" as a social requirements is attracted public attention, the policies and investments of the railway which have been less estimated than road is re-considered. Since the starting the commercial service (2004. April), the KTX have been operated successfully while transport passengers over 100million for years. And also the project for development of KHST (Korea High Speed Train ; G7) had been accomplished with a good result, the first trainset of KTX-II which base on G7 project was manufactured and testing now. On the other hand, the world's technology of the high speed train is more faster, and changing to a distributed traction system. To catch up the world's leading technology, the HEMU(High-speed Electric Multiple Unit) project will secure new technology and aims to promote the technology of domestic high-speed train. The authors indicates the result of detail review such as a curve, slope of the track and electrical dead section of the catenary to test at 400kph and also the performance simulation of the developed rolling stock in this paper. As the result, the authors devise the test scenario to perform a maximum speed test (stability at max. speed, acceleration & deceleration etc) with the restricted conditions such as track length, track available time etc by considering above result.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2009년도 춘계학술대회 논문집 특별세미나,특별/일반세션
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• pp.429-433
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• 2009

Since the "Low Carbon, Green Growth" as a social requirements is attracted public attention, the policies and investments of the railway which have been less estimated than road is re-considered. Since the starting the commercial service (2004. April), the KTX have been operated successfully while transport passengers over 100million for years. And also the project for development of KHST (Korea High Speed Train ; G7) had been accomplished with a good result, the first trainset of KTX-II which base on G7 project was manufactured and testing now. On the other hand, the world's technology of the high speed train is more faster, and changing to a distributed traction system. To catch up the world's leading technology, the HEMU(High-speed Electric Multiple Unit) project will secure new technology and aims to promote the technology of domestic high-speed train. The authors indicates the result of detail review such as a curve, slope of the track and electrical dead section of the catenary to test at 400kph and also the performance simulation of the developed rolling stock in this paper. As the result, the authors devise the test scenario to perform a maximum speed test (stability at max. speed, acceleration & deceleration etc) with the restricted conditions such as track length, track available time etc by considering above result.

• 한국철도학회논문집
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• 제15권2호
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• pp.104-108
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• 2012

현재까지 국내에서 운행되고 있는 고속철도차량용 창문은 전량 해외 제품의 수입에 의존하고 있다. 본 연구에서는 고속철도차량의 주행도중에 발생되는 공기 압력 변동 값을 반복적으로 생성시킬 수 있고 국제적으로 통용되는 규격에 부합하는 압력 내구성 시험을 수행할 수 있는 시험기의 개발에 대한 연구를 수행하였다. 따라서 향후 고속철도차량용 창문유리에 대한 압력 내구성시험기의 연구개발을 통하여 창유리의 국산화에 기여할 수 있을 것으로 사료된다.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2005년도 춘계학술대회논문집
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• pp.459-462
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• 2005

The KHST(Korean High Speed Train) which had been developed by through 'G7-R&D project' has succeeded trial running test up to 350km/h on the Kyoung-Bu High Speed Track in December 16th, 2004. In order to evaluate the function and characteristics of KHST, various experimental conditions have been considered and conducted. In this paper, measured current collection characteristics and dynamic behaviors of KHST's pantograph are analysed over 300 to 350km/h in running speed of KHST. A measuring system developed and installed on the KHST for measuring the performance and mechanical characteristics of the KHST's pantograph was used for this trial running test and eventually, we proofed that KHST has a remarkable and stable current collection characteristics as it had been designed.

• 한국소음진동공학회논문집
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• 제27권2호
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• pp.204-212
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• 2017

The rotor dynamics and balancing technic for rotating equipment during engineering and manufacture stage are to be carefully considered in order to minimize the operation troubles regarding vibration during commissioning stage. In this paper, the test rig, which includes the disks as balancing plane, is designed and manufactured, so that the characteristic of rotor dynamics can be analyzed such as critical speed and mode shape. The critical speed predicted through natural frequency analysis is verified by the actual measurement on bearing housing vibration during start-up condition of test rig. The low speed balancing and the operating speed balancing test are performed respectively with consideration of first critical speed, and the residual unbalance amounts are estimated in accordance with the relevant method described in API standard. In addition, the single and dual plane balancing are carried out on main disk and trim disk depended on phase information at each balancing step.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2004년도 춘계학술대회 논문집
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• pp.1286-1291
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• 2004

This paper was showed evaluation method and technical items for measurement test of new catenary system of Honam(Daejeon - Mokpo) conventional railway electrified. This line have tested by three type new electric rolling stocks in order to test construction quality and operation safety of a new catenary system with speed-up than conventional speed. We have some important experiences through measurement test of catenary system by new device installed on train roof.