• Transactions of the Korean Society of Mechanical Engineers A
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• v.38 no.5
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• pp.475-482
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• 2014

The precision hydraulic valve is widely used in various industrial field like aircraft, automobile, and general machinery. Servo actuator is the most important device for driving the precise hydraulic valve. The reliable operation of servo actuator effects on the overall hydraulic system. The performance of servo actuator relies on frequency response and step response according to arbitrary input signal. In this paper, we performed the analysis for the components of servo actuator to satisfy the reliable operation and response characteristics through the reliability analysis, and also induced the design parameters to realize the reliable operation and fast response characteristics of servo actuator for hydraulic valve operation through the empirical knowledge of experts and electromagnetic theories. We suggested the design equations to determine the values of design parameters of servo actuator as like bobbin size, length of yoke and plunger and turn number of coil, and verified the achieved design values through FEM analysis and performance tests using some prototypes of servo actuators adapted in hydraulic valve.

• The Journal of the Acoustical Society of Korea
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• v.17 no.6
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• pp.23-28
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• 1998

고분자 압전 필름인 PVDF를 이용하여 단일막과 이층막의 초음파 변환기를 제작하 여 임펄스 응답특성을 이론식에서 계산하여 실험적으로 확인하여 보았다. 또한 RF 펄스를 이용하여 초음파 변환기의 다층막에 따른 주파수 특성을 조사하였다. 그 결과 임펄스 응답 특성은 이론식과 잘 일치하였으며, 단일막의 변환기가 이층막에 비하여 지속시간이 짧은 펄 스를 나타내었다. RF펄스에 대한 주파수특성은 이층막의 변환기가 단일막에 비하여 광대역 의 특성을 나타냄을 알 수 있었다.

• Journal of the Korean Society for Railway
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• v.14 no.2
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• pp.160-166
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• 2011

It is difficult to clarify the dynamic response characteristics of trackbed because of various environmental conditions. However, track irregularity be affected by ununiformed bearing capacity and its dynamic response, study for dynamic response characteristics is required to investigate the cause of track irregularity and countermeasure. In this paper, the response variation for dominant frequency and vibration energy by trackbed structure and material stiffness are investigated. The analysis section is two layered ground structure that is comprised of trackbed and soft rock. This structure amplifies the energy of dominant range easily. It is evaluated to affect track irregularity on comparing by theoritical, analytical and empirical method for dynamic response of the trackbed.

• Progress in Medical Physics
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• v.5 no.2
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• pp.77-85
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• 1994

In this paper, the vibration response characteristics of individual's subjective are studied to whole-body and hand-arm induced vibration. For defining limits of vibration exposure to human, experimental data are investigated in a set of vibration criteria specified in ISO Standard 2631. Instrumentation requirements for evaluation of the responses of humans to vibration according to these criteria are discribed.

• Proceedings of the Acoustical Society of Korea Conference
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• 1998.06d
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• pp.9-12
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• 1998

공기경계층을 갖는 유리평판에서 힘의 크기가 10N이고 상승시간이 약 280ns 인 경사 점하중이 인가된 경우에 대하여 진앙점에서 입자 변위와 입자 속도를 계산하였다. 이론적으로 계산된 수직성분이 입자속도가 PZT변환자에 입사한다고 가정하여 PZT 변환자의 과도 응답특성을 Mason 등가회로와 격자점을 이용하여 계산하였다. 유리모세관의 파과시에 방출괴는 과도탄성파를 이용하여 유리평판의 진앙점에서 PZT 변환기의 응답을 조사하였고, 이론과 비교한 결과 상당히 일치하였다. 이를 이용하여 음향방출 시스템인 발생원, 전파매질, 변환자 및 신호분석시스템을 수학적으로 모형화할 수 있는 기초를 마련하였다.

• Journal of the Korean Society of Propulsion Engineers
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• v.13 no.1
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• pp.19-26
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• 2009

The response characteristics of $H_2O_2$ monopropellant thrusters at a pulse mode were presented in this paper. A catalyst bed was fixed to $MnO_2$/$Al_2O_3$ to investigate the thruster design effect to response time. Three different thrusters (50 N class) having different injectors, ullage volumes, catalyst grain sizes, and reactor volumes were prepared to investigate the response characteristics. As a result, the ignition delay, pressure rising and tail-off time of case 2-2 thruster with 16-20 mesh catalyst size were 14, 108, 94 ms respectively, which were comparable to requirement of response time at commercial hydrazine thrusters.

• Journal of Korean Association for Spatial Structures
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• v.11 no.2
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• pp.119-127
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• 2011

The purpose of this study is to propose damper system which is easy to design, which can ensure against risks, and to verify earthquake response characteristics. For this study, the pseudo dynamic earthquake response tests carried out for steel frames with metallic damper. As a result, in case of using the metallic damper as a vibration control device proposed by this study, the damper having higher stiffness than main-structure turned to the state of plasticity by little displacement has been proved to be able to absorb earthquake energy.

• The Journal of Engineering Geology
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• v.11 no.1
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• pp.25-35
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• 2001

For the ground resrxmse analysis, both in-situ and laboratory testing techniques such as downhole, SASW, resonant column and torsional shear tests were perlormed for Hong-Seong area. The grOlmd upper 30m is classified as SD since it has an average shear wave velocity as 209m/s. The response specLrums obtained by site-specific analyses generally satisfied the seismic code, but near the resonance period the motion was evaluated to be higher than the code.

• Proceedings of the Korea Institute of Fire Science and Engineering Conference
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• 2011.11a
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• pp.31-34
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• 2011

본 논문은 소방용 무선주파수로 도입 예정인 447 MHz와 2.4 GHz의 응답특성을 확인하고자, 한국소방산업기술원에서 개발된 447 MHz 무선모듈과 2.4 GHz 무선모듈을 이용하여 건축물 내에서 무선통신 환경에 영향을 줄 수 있는 대표적 장애물인 벽체를 시료로 하여 두 주파수 간의 응답특성을 비교 분석하였다. 도출된 결과를 바탕으로 향후 도입될 소방용 무선주파수 선정을 위한 기초 자료로 활용하고자 한다.

• Proceedings of the Korea Institute of Fire Science and Engineering Conference
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• 2011.11a
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• pp.187-190
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• 2011

본 논문은 초기화재 및 훈소화재에 적응성이 있는 CO센서의 응답특성을 분석하고자 접촉식 CO센서를 실험대상으로 하여 한국소방산업기술원의 실화재시험장에서 모형화재실험을 실시하였다. 화원의 종류로는 UL 268 시험화원인 종이, 목재, 인화성액체를 화원으로하여 각 화원에 따른 CO센서의 응답특성을 비교 분석하였다.