데이터 배선 용량 최소화를 위한 비정질 실리콘 박막 트렌지스터 배열의 최적화 설계와 구현

김창원,윤정기,김선용,김종효,Kim, C.W.,Yoon, J.K.,Kim, S.Y.,Kim, J.H. 대한의용생체공학회 2008 의공학회지 Vol.29 No.5

Thin-film transistor (TFT) arrays for an x-ray detector require quite different design concept from that of the conventional active-matrix liquid crystal devices (AM-LCDs). In this paper anew design of TFT array which uses only SiNx for passivation layer is described to meet the detector performance and the product availability simultaneously. For the purpose of optimizing the design parameters of the TFT array, a Spice simulation was performed. As a result, some parameters, such as the TFT width, the data line capacitance, and the storage capacitance, were able to be fixed. The other parameters were decided within a permissible range of the TFT process especially the photolithography process and the wet etch process. Then we adapted the TFT array which had been produced by the proposed design to our prototype model (FDXD-1417 and evaluated it clinically by comparing with a commercial model (EPEX, Hologic, Beford, USA). The results say that our prototype model is slightly better than EPEX system in chest PA images. So we can prove the technical usefulness and the commercial values of the proposed TFT design.

비정질 셀레늄층과 비정질 실리콘TFT배열을 사용하는 디지털 X-선 검출기의 영상특성 평가

김창원,윤정기,김종효,Kim, Chang-Won,Yoon, Jeong-Key,Kim, Jong-Hyo 한국의학물리학회 2008 의학물리 Vol.19 No.4

이 연구에서는 저자들이 개발한 비정질 셀레늄층과 비정질 실리콘TFT배열을 사용하는 직접방식 디지털 X-선 영상 검출기에 대해 IEC (international electrotechnical commission)와 같은 국제표준으로 권고된 측정방법에 따라 특성을 평가하였다. 영상 성능 묘사에 사용되는 측정은 응답특성(response characteristic), 변조전달함수(MTF, modulation transfer function), 잡음전력스펙트럼(NPS, noise power spectrum), 양자검출효율(DQE, detective quantum efficiency), 양자제한 성능을 포함하고 있다. 영상특성평가 결과, 개발된 검출기의 DQE 값은 최저주파수와 최고주파수에서 각각 40%와 25%이었다. 해외 타사의 제품과 비교해서도 우월한 값을 나타내었다. 또한 MTF는 간접방식 DR, CR과 비교하면 매우 우월한 성능을 보이고 있다. 또한 양자 제한된 특성을 평가한 결과, 0.023 mR 이하에서만 제한된 특성을 보여 일반촬영용도로서 적합성을 확인할 수 있었다. In this study, we have conducted characterization of imaging performance for a flat panel digital X-ray detector using amorphous Selenium and a-Si TFT which was developed by the authors. The procedures for characterization were in concordance with internationally recommended standards such as IEC (international electrotechnical commission). The measures used for imaging performance characterization include response characteristic, modulation transfer function (MTF), detective quantum efficiency (DQE), noise power spectrum (NPS), and quantum limited performance. The measured DQEs at lowest and highest spatial frequencies were 40% and 25% respectively, which was superior to that of commercial products by overseas vendor. The MTF values were significantly superior to that of CR and indirect type DRs. The quantum limited performance showed the detector was limited by quantum noise at the entrance exposure level below 0.023 mR, which is sufficiently low for general X-ray examination.

광섬유 마이켈슨 간섭계형 교류 전류 센서

김창원,박동수,김명규,이정희,강신원,손병기 ( Chang Won Kim,Dong Su Park,Myung Gyoo Kim,Jung Hee Lee,Shin Won Kang,Byung Ki Sohn ) 한국센서학회 1995 센서학회지 Vol.4 No.2

A Michelson interferometric AC current sensor has been fabricated by using a single mode optical fiber and a cylindrical PZT tube of which a radial dimension varies with applied voltage. The signal processing scheme used in this work, measures the magnitude of AC current regardless of the frequency of the current. An AC current is measured by counting the number of interference fringe during half cycle of the AC current. he number of interference fringes varies linearly with the magnitude of the current and the error range is within 5% at the temperature range from -20 ℃ to 80 ℃.

IMT-2000 & PCS 무선대역전송용 광 송수신기 제작 및 특성분석

김창원,김병직,오윤제,양광진,Kim, Chang-Won,Kim, Byeong-Jik,O, Yun-Je,Yang, Gwang-Jin 대한전자공학회 2000 電子工學會論文誌-TC (Telecommunications) Vol.37 No.7

In this paper, we proposed an fiber-optic transceivers based on the analog optical transmission techniques of incorporating the SCM (subcarrier multiplexing) and WDM (wavelength-division multiplexing ) method, which can be used to transmission of IMT-2000 and PCS wireless frequency band and analyzed overall those parameters related with fabrication. Especially in the impedance matching network between RF signal and LD, we proposed the method of deriving optimal performance using simulation techniques. In the frequency band of 1.7GHz∼2.25GHz, experimental data for the gain flatness and the noise floor of the optical link were also presented $\pm$1.5dB and -130dBm respectively when the link Rain was 0dB. 본 논문에서는 SCM과 WDM방식의 아날로그 광 전송기술을 기반으로 IMT-2000 및 PCS 양 무선주파 수대역 전송에 사용 가능한 광 송수신기의 구조를 제안하고 이의 제작에 관련된 여러 파라미터들을 분석하였다. 특히 송신부의 고주파 신호와 LD사이의 임피던스 정합회로는 시뮬레이션을 통해 최적의 성능을 도출 하는 방법을 제안하였고, 또한 1.7GHz∼2.25GHz 대역에서 광 링크의 gain이 0dB일 때, 광 링크의 gain flatness 및 noise floor가 각각 ±1.5dB 및 -130dBm인 결과를 얻었다

표준화된 MIP기법을 이용한 삼차원 CT문맥조영술: 간경화 환자의 문맥전신측부순환 평가에 있어서의 유용성

김창원,이준우,이석홍,Kim, Chang-Won,Lee, Jun-U,Lee, Seok-Hong 대한영상의학회 2003 대한영상의학회지 Vol.49 No.2

목적:간경화 환자의 문맥전신측부순환의 평가에 있어서 표준화된 maximal intensity projec-tion (MIP)기법으로 얻은 삼차원 CT문맥조영술의 유용성을 평가해 보고자 하였다.대상과 방법:다검출나선식 CT를 촬영한 환자 중 간경화에 동반되어 문맥전신측부순환이 형성된 25명의 환자를 대상으로 하였다.후기동맥기 영상을 computer workstation으로 전송한후 표준화된 방법과 표준화 하지 않은 MIP기법으로 삼차원 CT문맥조영술 영상을 얻었으며각각 재구성 영상을 만드는데 걸리는 시간을 측정하였다.표준화된 MIP 영상은 총 8개의 평면으로 얻었는데,즉 비정맥-문맥 접합부위에서 coronal,lordotic coronal,lordotic coronal RAO 30 。,lordotic coronal LAO 30 。영상을 얻고,좌신정맥을 축으로 하는 lordotic oronal 영상을 얻었다.추가로 식도하부,위저,비문 부위에서 횡단면 MIP 영상을 얻었다.두 기법에의해 만들어진 영상을 2명의 방사선과 의사의 합의 하에 문맥전신측부순환을 평가하고,이를 서로 비교하였다.문맥전신측부순환의 평가는 좌위정맥의 확장,식도정맥류,식도주위정맥류, 위정맥류,비정맥류,제대주위정맥의 확장,비-신정맥문합,위-신정맥문합,그 외 장간막측부 순환,후복막강정맥문합,대망측부순환의 존재 유무를 평가하였다. 결과 :표준화하지 않은 MIP기법을 이용한 문맥조영술은 만드는데 평균 11분 23초 소요되었으며,표준화된 MIP기법을 이용한 문맥조영술을 얻는 데는 평균 6분 5초 소요되었다. 표준화된 MIP기법을 이용한 삼차원 CT 문맥조영술에선 좌위정맥의 확장은 25예,식도정맥류,식도주위정맥류,위정맥류,비정맥류는 각각 18예,13예,4예,4예에서 관찰되었다.제대주위정맥의 확장은 4예,비-신정맥,위-신정맥,위-비-신정맥문합의 경우는 각각 3예,3예,1예가 관찰되었다.표준화하지 않은 MIP기법에선 표준화된 MIP기법에서와 같은 문맥전신측부순환이 관찰되었으나,추가로 비정맥류 1예,장간막측부순환 4예,후복막강정맥문합 3예,대망측부순환이 2예가 관찰되었다. 결론:표준화된 MIP 기법을 이용한 삼차원 CT 문맥조영술은 간경화 환자의 문맥전신측부순환을 평가하는데 좋은 방법이며,영상을 재구성하는 개인적인 차이를 없애고,영상의 재구성시간을 단축시키는데 도움이 될 것으로 생각한다. Purpose: To assess the usefulness of three-dimensional CT portography using a standardized maximum intensity projection (MIP) technique for the evaluation of portosystemic collaterals in cirrhotic patients. Materials and Methods: In 25 cirrhotic patients with portosystemic collaterals, three-phase CT using a multidetector-row helical CT scanner was performed to evaluate liver disease. Late arterial-phase images were transferred to an Advantage Windows 3.1 workstation (Gener Electric). Axial images were reconstructed by means of three-dimensional CT portography, using both a standardized and a non-standardized MIP technique, and the respective reconstruction times were determined. Three-imensional CT portography with the standardized technique involved eight planes, namely the spleno-portal confluence axis (coronal, lordotic coronal, lordotic coronal RAO 30 degree, and lordotic coronal LAO 30 degree), the left renal vein axis (lordotic coronal), and axial MIP images (lower esophagus level, gastric fundus level and splenic hilum). The eight MIP images obtained in each case were interpreted by two radiologists, who reached a consensus in their evaluation. The portosystemic collaterals evaluated were as follows: left gastric vein dilatation; esophageal, paraesophageal, gastric, and splenic varix; paraumbilical vein dilatation; gastro-renal, spleno-renal, and gastrospleno-renal shunt; mesenteric, retroperitoneal, and omental collaterals. Results: The average reconstruction time using the non-standardized MIP technique was 11 minutes 23 seconds, and with the standardized technique, the time was 6 minutes 5 seconds. Three-dimensional CT portography with the standardized technique demonstrated left gastric vein dilatation (n=25), esophageal varix (n=18), paraesophageal varix (n=13), gastric varix (n=4), splenic varix (n=4), paraumbilical vein dilatation (n=4), gastro-renal shunt (n=3), spleno-renal shunt (n=3), and gastro-spleno-renal shunt (n=1). Using three-dimensional CT portography and the non-standardized MIP technique, the portosystemic collaterals demonstrated were similar to those demonstrated using the standardized technique. Additionally, howerer, the former revealed features not revealed by the latter, namely splenic varix (n=1), mesenteric collaterals (n=4), retroperitoneal collaterals (n=3), and omental collaterals (n=2). Conclusion: In patients with liver desease, three-dimensional CT portography using a standardized of MIP technique helps evaluate portosystemic collaterals, reduces interobserver bias, and saves reconstruction time.

이슈진단 및 분석 - 교무.학사의 현안과 대학의 미래

김창원,Kim, Chang-Won 한국대학교육협의회 2014 大學敎育 Vol.184 No.-

하수처리장 실시간 제어.진단 운영 기술 동향

김창원,김예진,Kim, Chang-Won,Kim, Ye-Jin 한국수자원학회 2011 물과 미래(한국수자원학회지) Vol.44 No.8

실용적 적용을 위한 미생물연료전지의 운전 조건과 설계 인자

김창원,차재환,최수정,유하나,Kim, Chang-Won,Cha, Jae-Hwan,Choi, Soo-Jung,Yu, Ha-Na 대한환경공학회 2009 대한환경공학회지 Vol.31 No.9

배향된 $\beta-Si_3N_4$ Whisker를 함유하는 $Si_3N_4$ 복합체의 기계적 특성에 미치는 소결조제와 소결온도의 영향

김창원,최명제,박찬,박동수,Kim, Chang-Won,Choi, Myoung-Jae,Park, Chan,Park, Dong-Soo 한국세라믹학회 2000 한국세라믹학회지 Vol.37 No.1

Gas pressure sintered silicon nitride based composites with 5 wt% $\beta$-Si3N4 whiskers were prepared, and the variations depending on sintering additives and sintering temperature were studied. Sintering additives were 6 wt% Y2O3-1 wt% MgO(6Y1M), 6 wt%Y2O3-1 wt% Al2O3(6Y1A), 6 wt% Y2O3-1 wt% SiO2(6Y1S), and whiskers were unidirectionally oriented by a modified tape casting technique. Samples were fully densified by gas pressure sintering at 2148 K and 2273 K. As the sintering temperature increased, the size of large elongated grains was increased. Three point flexural strength of 6Y1M and 6Y1M samples was higher than that of 6Y1S sample, and the strength decreased as the sintering temperature increased. The indentation crack length became shorter for the sample sintered at higher temperature, and the difference between the cracks length parallel to and normal to the direction of whisker alignment was decreased. In case of cracks 45$^{\circ}$off the whisker alignment direction, the crack length anisotropy disappeared.

환경공학 교육의 현황과 발전 과제

김창원,Kim, Chang-Won 한국대학교육협의회 1997 大學敎育 Vol.89 No.-