• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2016.10a
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• pp.703-705
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• 2016

In this paper, we developed a wideband PIMD system to measure passive intermodulation distortion signals of mobile communication RF passive module. To represent wideband characteristic, we designed a receiver that meets low-noise and wideband characteristics in RF receiver. It allows high dynamic range in the RF receiver front end. In designed passive intermodulation distortion measurement system, we programed to display a PIMD signal with FPGA/DSP at PC. Implemented PIMD system was variable from 650 MHz to 2700 MHz and show up to -138 dB minimum detectable $3^{rd}$ passive inetrmodulation distortion signal.

• Transactions of the Korean Society of Mechanical Engineers
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• v.11 no.5
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• pp.846-855
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• 1987

The experimental study was carried out to investigate the performance characteristics of the aero-valved pulsating combustor designed to increase the practical applications of the system. The geometric effect on the stable condition and the dynamic behavior of the system is identified. The equivalence ratio, the inflammability limit, the operating frequency, and thrust were also measured when the system oscillated stably. It is found that while the operating condition is sensitive to the diameter of the inlet pipe and the length of the tailpipe, the maximum value of the turn down ratio was obtained up to 3.2. The measured air flow rate shows that the equivalence ratio increases monotonously with the increasing fuel flow rate and decreasing air inlet diameter and tailpipe length. The measured operating frequency can be approximated by the simple linear equation and the discrepancy is within five percent. The system produced the maximum total thrust of 14N and the minimum specific fuel consumption of 0.155 Nm$^{3}$/h.N when the total thrust was 13N.

• Journal of the Korea institute for structural maintenance and inspection
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• v.8 no.3
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• pp.263-270
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• 2004

The dynamic behavior of multi-layered stone masonry monuments, such as stone pagoda, are mainly influenced by contour condition of contacting surface of stones. These structures can be modeled as a multi-degrees of freedom system. In this case the mass of the system can be easily estimated, mean while the estimation of stiffness at junction is not simple. In this paper a method for estimating the spring constant at the contacting surface of stone is proposed. The proposed method utilizes the natural frequency of the system which can be obtained by eigenvalue analysis.

• Proceedings of the Korea Information Processing Society Conference
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• 2000.10b
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• pp.1609-1612
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• 2000

무선망에서 기존의 회선 서비스뿐만 아니라 패킷 서비스 및 영상 서비스 등을 수용하는 데 있어서 고려되어야 할 것들 중 하나는 무선 자원의 활용이다. 특히 패킷 서비스의 경우 가변적인 패킷의 길이와 양으로 효율적인 무선 자원관리를 어렵게 하는 요소를 지니고 있다. 즉, 무선 자원을 효율적으로 운용하기 위해서는 동적인 무선 자원할당 메커니즘이 중요한 역할을 한다. UMTS 표준 문서에서는 계층 2 전송 프로토콜인 RLC (Radio Link Control) 버퍼의 양만을 측정하여 무선 자원 할당이 제어가 되도록 권고하고 있다. 하지만 트래픽 양의 변화가 큰 VBR 트래픽의 경우, 이와 같은 방법은 갑자기 증가하거나 감소하는 트래픽 양에 적응하기 힘들고 이는 무선 자원의 효율성을 저하시키며, QoS 제공도 어렵다. 본 논문에서는 먼저 트래픽 특성을 알 수 있는 토큰 버켓 모델을 RLC에 적용하고, 동적 무선 자원 할당을 위해 RLC 버퍼의 양뿐만 아니라 예상되는 유입 트래픽 양을 측정 및 보고하는 메커니즘을 제안한다.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 1998.05a
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• pp.405-408
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• 1998

In this paper, We analyzed the current-voltage characteristics with n-type silicon substrates concentration and temperature variations (Room temperature, 5$0^{\circ}C$, 75$^{\circ}C$) in platinum silicide and silicon junction. Measurement electrical parameters are forward turn-on voltage, reverse breakdown voltage, barrier height, saturation current, ideality factor, dynamic resistance acceding to junction concentration of substrates and temperature variations. As a result, the forward turn-on voltage, reverse breakdown voltage, barrier height and dynamic resistance were decreased but saturation current and ideality factor were increased by substrates concentration variations. Reverse breakdown voltage and dynamic resistance were increased by temperature variations.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2012.10a
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• pp.619-620
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• 2012

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2009.04a
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• pp.124-125
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• 2009

• Proceedings of the KSEE Conference
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• 2009.10a
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• pp.19-23
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• 2009

• 한국항공운항학회:학술대회논문집
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• 2006.11a
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• pp.115-119
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• 2006

• Journal of the Korean Society for Nondestructive Testing
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• v.21 no.2
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• pp.147-151
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• 2001

An optical fiber sensor is capable of nondestructive measurement of a structure and it has an advantage of the immunity to electromagnetic interference because light is not affected by electromagnetic wave. In addition, if optical fibers are buried in an object like a concrete, this sensor tan analyze defects and physical status of the object without disassembling it. Especially, the fiber Bragg grating sensor is a promising optical fiber sensor capable of nondestructive test of such an object. A fiber Bragg grating has the characteristics of reflecting or blotting light of a specific wavelength. If we apply physical quantity like strain to the fiber Bragg grating, the center wavelength of the reflected light is shifted and then we can find the physical quantity applied to the fiber Bragg grating by measuring the center wavelength shift of the reflected light. The fiber Bragg grating sensor capable ot static and dynamic strain measurement is being used in health-monitoring of buildings, structures, etc. Recently increasing is interest in dynamic strain measurement inevitable to the civil structures such as roads and bridges. In this study we implemented the optical fiber sensor system which can measure dynamic strain at multiple points using Fabry-Perot wavelength demodulation. And we measured the static and dynamic strain using this sensor system with a test structure(cantilever). Measurement results were similar to those obtained with the conventional electrical measurement methods.