• The Journal of the Acoustical Society of Korea
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• v.4 no.2
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• pp.48-55
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• 1985

포물선형 혼 도파관을 사용하여 입사파의 음향전력밀도를 증대시킴으로써 압전물질의 압전비선 형성을 이용한 평판형 구조의 탄성 음향파 콘벌버를 제작하고 스펙트럼 확산 통신방식에서 S/N 비가 S 높으며 프로그램이 가능한 자기상관정합 필터로 사용될 수있음을 실험적으로 제시하였다. 본 실험에서 는 포물선형 혼 도파관을 사용한 탄성 음향파 콘벌버를 압전 재료인 YZ-LiNbO\sub 3\ 위에 중심 주파 수 100MHz 압축비 11:1, 적분시간 6인 IDT, 포물선형 혼 도파관 및 출력단자를 설계한 후 이를 포토리 토그라피 바업으로 제작하여 100 MHz 로 펄스 변조된 신호를 탄성 음향파 콘벌버의 양 입력에 인가하 여 자기상관 출력을 얻음으로써 신호 처리 이득이 18dB인 정합필터를 구현하였다.

• Journal of the Korean Vacuum Society
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• v.4 no.4
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• pp.413-416
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• 1995

고주파 마그네트론 스펏터링법을 이용하여 ZnO막을 제조하고 유리기판 위에 ZnO-SAW필터를 제작하였다. ZnO막의 제조 조건은 고주파 전력 150W, 기판온도 $200^{\circ}C$, 분위기압 5mTorr 및 O2/(Ar+O2)비 50%였다. 한편 IDT(Inter-digital transducer)전극은 전극 폭을 2.56mm, 전극 거리를 2,936mm, λ/8폭을 $8mu$m로 설계하였다. 제작된 ZnO-SAW필터의 주파수 응답을 측정하기 위해 소자는 mount(TO8)에 고정시켰다. ZnO SAW필터의 통과 대역(3 dB대역폭)은 345.2~44.8 MHz로 9.6MHz의 대역 폭을 나타내었으며 중심주 파수는 40 MHz를 나타내었다. 또한 삽입 손실은 39 dB, 통과 대역에서의 리플(ripple)은 $\pm$ 0.8 dB 및 rejection은 17 dB를 나타내었다.

• Proceedings of the KIEE Conference
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• 2009.07a
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• pp.1515_1516
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• 2009

A 440MHz wireless and passive surface acoustic wave (SAW) based micro-sensor was developed for simultaneous measurement of temperature and humidity. The developed sensor is composed of a SAW reflective delay lines structured by an IDT (Inter-Digital Transducer), four reflectors and humidity sensitive film (polyimide). Polyimide was dry-ecthed by RIE (Reactive Ion Etching) to obtain high roughness, which gives the large reaction area resulting in high sensitivity. In wireless testing using a network analyzer, sharp reflection peaks with high S/N ratio, small signal attenuation, and few spurious peaks were observed in the time domain. High sensitivity towards the temperature and humidiy were also observed in the large concentration range. The obtained sensitivity was $16.8^{\circ}/^{\circ}C$ for temperature sensor and $15.8^{\circ}$/%RH for humidity sensor.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.54 no.2
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• pp.83-90
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• 2005

In this paper, we proposed the newly design method for extracting of the saw resonator characteristic. For the parameters of the proposed equivalent model, we adjusted and optimized the variables of several functions. As verification of proposed method, we firstly designed and fabricated cellular saw resonator by using the proposed model resonator. As the simulated and measured results of the proposed design method are almost equaled, we confirmed the usefulness of this method. we knew the usefulness of this method. Finally we designed the 800MHz cellular Tx/Rx band pass filter by using this designed resonator.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2004.05a
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• pp.563-567
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• 2004

In this paper, a remote temperature sensor based on surface acoustic wave is introduced and the issues on design, manufacturing, and test of the sensor are addressed. SAW sensors having single and double electrode are prepared on the 128$^{\circ}$ YX-LiNbO$_3$ Substrate. The frequency responses of SAW sensors on the temperature change are compared. To measure the change of center frequency, two center frequencies on the 3dB and 20dB are measured and compared. Since the center frequency on the temperature change from -30$^{\circ}C$ to 80$^{\circ}C$ is linearly changed, the SAW sensor is applicable to the temperature sensor.

• Proceedings of the Korea Electromagnetic Engineering Society Conference
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• 2003.11a
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• pp.140-144
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• 2003

To investigate failure analysis of surface acoustic wave (SAW) filter for radio frequency, high temperature storage test was carried out. The failure criteria were insertion loss at passband and rejection level at stopband. As a result, the insertion loss at passband increase about 4 dB was due to damages of interdigital transducer (IDT). That is caused by poor adhesion between metal electrode(AI) and piezoelectric substrate and defects on a manufacturing process. This result indicates that good adhesion between electrode and ceramic substrate is important factor And also we investigated the demage factors of electrode. Screen possible of saw filter using high temperature storage test(HTOL) in the manufacturing phase be presented.

• Proceedings of the Korean Vacuum Society Conference
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• 2014.02a
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• pp.392.1-392.1
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• 2014

Isoindigo based small molecules have attracted much attention in the field of optoelectronic devices due to their broad absorbance and high charge carrier mobilitiies. Herein, we investigate the field effect transistor characteristics of a series of isoindigo based donor-acceptor-donor (D-A-D) small molecules containing a variable number of thiophene moieties (named IDT, ID2T, and ID3T) which form pi-bridges between the D and A moieites and a different donor moiety (IDED). In order to improve the carrier mobility, 1-chloronaphthalene (CN) and 1,8-diiodooctane (DIO) as solvent additives were used. The film morphology, crystallinity and optical properties of the materials processed with various concentrations of solvent additives were investigated through atomic force microscopy (AFM), X-ray diffraction (XRD) and UV-vis absorption spectroscopy.

• Journal of the Korean Society for Nondestructive Testing
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• v.10 no.2
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• pp.56-62
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• 1990

Surface Acoustic Waves(SAW) are generated on silicon wafer and $YZ-LiTaO_3$ substrate and are detected by noncontact method. As wave sources two kinds of transducers are used : the wedge-type of 20.0 MHz and fabricated Interdigital Transducer(IDT) of 20.8 MHz. SAW are modulated by the optical chopper frequency and are syncronized with a laser beam. In signal processing, intensity variations of light due to the intensity of SAW are analyzed using lock- in amplifier. From the results, corresponding to the applied input power, the intensity variations of a deflected light by corrugations on the substrates are increased and saturation phenomenon is observed.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2018.06a
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• pp.84.2-84.2
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• 2018

최근 사람의 후각으로는 감지하기 어려운 유해, 폭발성 가스로 인한 안전사고 발생이 많아짐에 따라 높은 감도를 지닌 가스 센서의 필요성이 커지고 있다. 특히 가스 검지층으로 감도 및 안정성이 뛰어난 $SnO_2$를 이용한 가스 센서 연구와 더불어 촉매 효과에 대한 연구도 활발히 진행 중이다. 본 연구에서는 물리기상증착 공정의 증착압력 등 조건들을 변화시켜 형성한 다공성 나노 구조의 $SnO_2$ 가스 검지층 위에 촉매물질을 Sputtering 방식을 이용하여 증착하였다. SEM 분석을 통해 $SnO_2$ 검지층 내 촉매물질의 분포를 확인하였다. IDT 전극 기판 위에 먼저 나노 구조의 $SnO_2$ 가스 검지층을 형성하였고 그 후에 촉매물질을 증착하였다. 제작된 샘플은 $700^{\circ}C$에서 1시간동안 튜브 퍼니스로 열처리를 진행한 뒤 챔버 내에서 측정을 진행하였다. 측정은 $300^{\circ}C$에서 CO 농도, 습도를 변화시키며 감도, 반응시간, 회복시간에 대하여 분석하였다.

• Proceedings of the Korea Information Processing Society Conference
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• 2017.11a
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• pp.428-431
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• 2017

기업의 성장성과 기업 주식가치를 매출, 매출원가, 영업이익율 등의 정형데이터와 경제, 경영관련 뉴스 등 비정형 데이터를 토대로 다양한 알고리즘을 활용해 분석하고, 그 결과의 유의성을 검증한다. 주성분회귀분석, 인공신경망, 나이브 베이지안 분류자, 긍/부정 사전분석 모델을 통해 분석된 결과를 검토하여 각 분석모델 별 성능을 확인하고, 기업 성장성 예측을 위해 활용 가능한 모델과 필요한 데이터를 제시한다.