• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2000년도 추계학술대회논문집
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• pp.568-574
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• 2000

This paper presents the vibration characteristics of a continuous circular cylindrical shell multi-simply supported at arbitrary axial positions for searching design parameters. In this modal test the impulse test method is applied to the excitation of experimental model. Natural frequencies are obtained from the peak points of frequency response function(FRF) through frequency analyzer and vibration behaviors are investigated. FE analysis is performed with ANSYS 5.5 to improve the reliability of experimental results. Their results are compared with experimental results. The effect of dynamic characteristics is analyzed for the number of support point on the shell.

• 한국생산제조학회지
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• 제9권2호
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• pp.52-58
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• 2000

the quality of a TV is closely connected with the high quality surface of Braun tube. To get high quality surface an improved grinding system is needed. It has three main parts : the housing part of supporting frame the outershaft part rotat-ed by motor and the innershaft part having eccentricity from the rotation axis of the outershaft. the housing part and the outershaft part are connected by outerbearings, The outershaft part and the innershaft part are connected by innerbearings. Although the outershaft part is rotated at high-speed the innershaft part is not rotated by offset coupling. The high quality grinding surface can be obtained by this mechanism of panel surface grinder, Because the innershaft is unbalanced by eccentricity from rotation axis of outershaft the unbalancing vibration is resulted In this rotor system with high-speed rota-tion the unbalancing vibration makes the opertion unstable. In this research the transfer function is obtained bythe frequency response analysis of finite element model. The simu-lation result is proved by comparing with the experimental result measured by signal analyzer Then the results are corre-lated. in order to improve the design an optimization method is used instead of two-planes balancing method The parts of the 3-dimensional panel surface grinder satisfy the each constraint, The result shows that the design of the panel surface grinder can be optimized.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2005년도 추계학술대회 논문집 Vol.18
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• pp.285-286
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• 2005

Organic photovoltaic properties were studied in ZnPc/$C_{60}$ heterojunction structure by varying the organic layer thicknesses and exiton blocking layer(EBL). Current density-voltage characteristics of organic photovoltaic cells were measured using Keithley 236 source-measure unit, a 500W xenon lamp (ORIEL 66021) for a light source and Agilent 4294A impedance analyzer in the range of 40 Hz $\sim$ 1 MHz. From the analyses of current-voltage characteristics such as short-circuit current density, open-circuit voltage and power conversion efficiency, optimum thickness of the organic layer were obtained and frequency response such as electrical conductance.

• 센서학회지
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• 제13권5호
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• pp.329-334
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• 2004

Functional residual capacity (FRC) is an important diagnostic parameter measured using $N_{2}$ analyzer. Since $N_{2}$ analyzer is expensive as well as cumbersome for use of noisy vacuum pump, the FRC measurement becomes possible only in large well-equipped hospitals. The present study introduced a new $TN_{2}$ wash-out technique to measure FRC by $O_{2}/CO_{2}$ analysis, which is relatively cheaper and much simpler to apply. Slower $O_{2}$ response was compensated for high frequency to be coincided with $CO_{2}$ response, thereby enabled indirect, but accurate $N_{2}$ concentration measurement. FRC was estimated by continuous integration of expired $N_{2}$ volume obtained with air flow signal. Experiment with 3 L syringe, a standard calibration device recommended by the American Thoracic Society, demonstrated less than 1% error at 0, 1, and 2 L. Correlation coefficient was almost ideal, guaranteeing linear estimation of FRC. The present technique is inexpensive and simple to apply, thus should he of great convenience.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2003년도 하계종합학술대회 논문집 II
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• pp.759-762
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• 2003

The epitaxially grown Mg-doped GaN thin film was prepared by MOCVD (Metal Organic Chemical Vapor Deposition) for a SAW(Surface Acoustic Wave) filter. Mg-doped GaN thin film had enough properties for a SAW filter which include crystallinity and morphology. The surface morphology and crystalline of the Mg-doped GaN thin films were characterized using AFM and an X-ray rocking curve. The SAW filter, which was fabricated by lift-off process and frequency response, was measured by HP 8753C network analyzer. Center frequency was 96.687 MHz and SAW velocity was 5801 m/s when wavelength(λ) was 60${\mu}{\textrm}{m}$. Insertion loss was over -10 dB, Q was factor over 200, and side lobe attenuation was over 22 dB which was suitable for use as a SAW filter. Electro-mechanical coupling coefficient (k$^2$) was calculated from the measured data. k$^2$ was from 1 % to 1.44 %. The fabricated SAW filter using Mg-doped GaN/sapphire structure has good qualities as a filter and will be used as a SAW filter for operating RF frequency.

• 한국전기전자재료학회논문지
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• 제25권6호
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• pp.445-450
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• 2012

We have developed an implantable wireless sensor for real time pressure monitoring of blood circulation system. MEMS (micro-electro-mechanical system) technology was adopted as a sensor development method. The sensor is composed of photolithographically patterned inductors and a distributed capacitor in gap between the inductors. A resulting LC resonant system produces its resonant frequency in range of 269 to 284 MHz at 740 mmHg. To read the resonant frequency changed by blood pressure variation, we developed a custom readout system based on a network analyzer functionality. The bench-top testing of the pressure sensors showed good mechanical and electrical functionality. A sensor was implanted into tibial artery of farm pig, and interrogated wirelessly with accurate readings of blood pressure. After 45 days, the sensor's electrical response and histopathology were studied with good frequency reading and biocompatibility.

• 전자공학회논문지D
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• 제36D권11호
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• pp.45-55
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• 1999

정상상태에서 반도체 소자의 전기적 특성을 분석할 수 있는 소신호 해석용 시뮬레이터를 개발하였다. 전위와 전자 및 정공 농도의 Slotboom변수에 대한 소신호 응답을 정의한 후 $S^3A$방법을 적용하여 ,DC 동작점에서 반도체 방정식을 선형화하였다. 행렬풀이를 위해 전진해법을 사용하여 메모리 소비량을 최소화하며 고주파 영역에서 소신호 해의 정확성을 향상시켰다. 구현된 알고리즘의 검증을 위해 3차원 구조를 갖는 N'P 다이오드 및 2차원 구조를 갖는 n-MOSFET에 대해 소신호 해석을 수행하여 MEDICI와 비교한 결과, 인가 전압에 따른 컨덕턴스와 캐패시턴스의 평균 상대 오차는 N'P 다이오드에서는 0.87%와 2.6%이고, n-MOSFET의 경우 7.75%와 2.24%로 나타났다. n-MOSFET에 대하여 입력신호의 주파수 변화에 따른 컨덕턴스와 캐패시턴스를 비교한 결과 MEDICI의 경우 10GHz까지 예측한 반면 본 논문이 제시한 방법을 이용한 모의실험은 100GHz까지 예측이 가능하여 고주파 영역에서 모의실험의 정확도가 향상됨을 확인하였다.

• 한국통신학회논문지
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• 제39C권6호
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• pp.476-481
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• 2014

본 논문에서는 가시광 통신의 광원으로 사용되는 백색 LED (Light Emitting Diode)의 변조 대역폭 확장을 위해 송신단에 전치 등화기 회로를 설계하였다. 또한 청색 광 필터를 이용하여 백색 LED의 주파수 응답을 저해하는 황색 형광물질의 영향을 제거하였고 이로 인해 발생하는 신호 세기의 저하를 광학 설계를 통해 극복하였다. 이 시스템을 통해 백색 LED의 변조 대역폭을 결정하는 3 dB 대역폭을 3 MHz에서 25 MHz이상으로 향상 시켰으며 광학 설계를 통해 추가적인 신호 세기를 확보하여 전송 거리를 증가시켰다. 통신 성능 확인을 위해 LED에 NRZ-OOK (신호를 변조시켜 전송하여, APD (Avalanche Photo Diode)를 통하여 수신하였고 이를 CSA (Communication System Analyzer)와 RFSA (Radio Frequency Spectrum Analyzer)를 통해 분석하였다. 이를 통해 전치 등화기와 광학 설계를 이용하여 전송거리 4.5 m에서 30 Mbps, 1.5 m에서 50 Mbps의 신호 전송이 가능함을 실험적으로 검증하였다.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2004년도 추계학술대회
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• pp.799-804
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• 2004

Dynamic characteristic of CD/DVD deck for vehicle is analyzed in this paper. Generally CD/DVD deck for vehicle is used from inferior environment with the vibration of the vehicle and shock of outside and so on. Therefore it must have the structure which is stabilized from the vibration to prevent read error. For this purpose, vibration characteristic of the deck for vehicle should be identified. To analyze characteristic of the deck system, we perform the signal analysis and modal testing using the FFT analyzer. Also we change the design factor degrading the performance of the deck system and verify the efficiency improvement using the acceleration measurement occurring to the sound discontinuation.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2009년도 제40회 하계학술대회
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• pp.336_337
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• 2009

전력용 변압기 운반, 설치, 고장전류 유입 등으로 권선 및 철심의 접지, 권선의 층간단락, 개방, 기계적 변형, 이탈, 구조물의 기계적 손상, 이완 등이 발생해도 현재 보유하고 있는 진단장비만으로는 정확한 이상 판단이 불가하여 변압기 해체 후 확인 하는 현실을 감안하여 변압기 기계적 변형 고장분석이 가능한 장비 도입이 필요한 시점이다. 또한 변압기 등 변전기기 고장 발생시 광범위한 고객 정전 및 복구비용이 발생(년 평균 3건)하고 있어 본 논문에서는 이러한 문제점을 해결하고자 2003년 한전에 도입된 SFRA(Sweep Frequency Response Analyzer) 주파수 반응 분석기의 진단 원리 및 권선변형 진단사례를 소개하고자 한다.