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디지털 X-선 영상 시스템 기반 촬영조건 변화에 따른 노이즈 특성 및 2개의 필터 조합을 이용한 개선 효과 연구
유원종,강성현,이용구,이영진 대한전자공학회 2018 전자공학회논문지 Vol.55 No.1
The purpose of this study was to evaluate image performances with various kVp and mAs and to analysis improvement effect using noise filtering in digital X-ray imaging system. First of all, we evaluated noise properties using acquired X-ray images as function of kVp and mAs. Then, Wiener filter, median filter and Gaussian filter were used in acquired images and coefficient of variation (COV) was calculated. Also, we designed new filters using 2 filter combination and evaluated COV after application of these filters. According to the results, the COV results decreased when we increased kVp and mAs and Wiener filter was superior in 1 filter situation. In addition, we confirmed lowest COV result by using Wiener-Median filter in 2 filter combination situation. In conclusion, we analyzed various noise filters in digital X-ray imaging system and our results demonstrated that 2 filter combination is better than 1 filter situation. 본 연구의 목적은 디지털 X-선 영상 시스템 기반 관전압 및 관전류 변화에 따른 노이즈의 특성 및 필터링을 통한 개선 효과를 분석하는 것이다. 먼저 관전압과 관전류 변화에 따른 X-선 영상을 획득하여 노이즈 특성을 분석하였다. 이어서, 각각의 촬영 영상을 Wiener 필터, Median 필터 및 Gaussian 필터를 적용하여 coefficient of variation (COV)를 평가하였다. 또한 위의 언급한 3종류의 필터들을 2종류씩 조합한 필터도 새롭게 모델링하여 적용한 후 COV를 비교 평가하였다. 결과적으로 관전압과 관전류가 증가함에 따라 COV값이 감소되는 것을 확인할 수 있었고, 1개의 필터를 사용하였을 경우 Wiener 필터가 가장 우수한 결과값을 도출하였다. 또한, 2종류를 조합한 필터 중에서는 Wiener-Median 필터가 낮은 COV값을 얻을 수 있었다. 결론적으로, 디지털 X-선 영상 시스템에서의 다양한 필터의 특성에 관하여 분석할 수 있었고, 2종류의 필터를 조합하는 경우 노이즈 감소 효율이 향상됨을 증명하였다.
Performance Enhancement of Thin Film LSCF Cathodes by Gold Current Collecting Layer
유원종,차석원,이예근,이윤호,조구영,박태현,Waqas Hassan Tanveer,김우성 한국정밀공학회 2016 International Journal of Precision Engineering and Vol.3 No.2
Performance improvement of a thin film lanthanum strontium cobalt iron oxide (La0.6Sr0.4Co0.8Fe0.2O1-δ, LSCF) cathode deposited by pulsed laser deposition (PLD) was achieved by utilizing a sputtered gold (Au) film as a current collecting layer. To improve low inplane electric conductivity of the porous LSCF film due to its columnar structure, fabrication of the well-connected and porous current collector is applied by sputtering. The effects of the Au current collecting layer for solid oxide fuel cells (SOFCs) with the LSCF cathode are electrochemically characterized. The cell without the current collecting layer shows 14 Ω·cm2 of ohmic resistance, while the cell with the current collecting layer exhibits 5.5 Ω·cm2 of ohmic resistance at 550 oC. In addition, the cell with the Au layer shows almost four times higher peak power density than the cell without the Au layer. Therefore, the results suggest that the puttered Au current collecting layer enables fabrication of porous LSCF cathode with enhanced electric conductivity and improves the performance of the fuel cell.
외상후 뇌손상 환자에서 Tc-99m-HMPAO 국소뇌혈류 SPECT 와 자기공명영상의 비교
유원종,이상훈,손형선,이한진,박정미,정수교,김춘열,박용휘,신경섭 ( Won Jong Yoo,Sang Hoon Lee,Hyung Sun Sohn,Han Jin Lee,Jeong Mi Park,Soo Kyo Chung,Choon Yul Kim,Yong Whee Bahk,Kyung Sub Shinn ) 대한핵의학회 1994 핵의학 분자영상 Vol.28 No.3
The purpose of this study was to compare Tc 99m HMPAO SPECT with MRI aft,er acute and subacute closed head injury. There were thirty two focal lesions in all cases of these, Fifteen lesions(47%) were seen on both MRI and SPECT. Fourteen lesions(44%) were seen only on MRI. Three lesions(9%) were seen only on SPECT. Of the 14 lesions seen only on MRl, one was epidural hematoma, two were subdural hematoma, three were subdural hygroma, one was intracerebral hematoma, four were contusion, and three were diffuse axonal injuries. SPECT detected 52% of the focal lesions found on MRI. For the detection of lesions, MRl was superior to SPECT in fourteen cases, while SPKCT was superior to MRI in three cases. In conclusion, there was a tendency that detection rate af the traumat,ic lesions was higher on MRI, but the SPECT could delineate more wide extent, of lesion.
Effects of Microstructure of Ni Anode on Nanotemplate Based Low Temperature Solid Oxide Fuel Cells
유원종,Sangbong Ryu,Waqas Hassan Tanveer,Gu Young Cho,Suk Won Cha 한국정밀공학회 2020 International Journal of Precision Engineering and Vol.21 No.11
For nano-porous anodized aluminum oxide (AAO) template based low temperature solid oxide fuel cells (LT-SOFCs), anode structure has crucial effects on electrochemical characteristics because of triple phase boundary densities and electrical connectivity of metal catalysts on porous AAO substrates. In this study, we investigated effects of fabrication processes of Ni anode for AAO template based LT-SOFCs. Ni anodes were prepared at various deposition pressure, i.e. low pressure, high pressure and low pressure–high pressure, on nano-porous AAO substrates by physical vapor deposition. Surface morphology and cross-sectional structure of various Ni anodes were systematically evaluated. Electrochemical characterizations of LTSOFCs with various anode structures were successfully conducted at 500 °C. The Ni anode prepared at low pressure showed high electrical conductivity and low catalytic activity. However, Ni anode which was fabricated at high pressure exhibited poor electrical conductivity and good catalytic activity. Bilayer Ni anode which was deposited in sequence at low pressure and high pressure presented both good electrical conductivity and good catalytic activity. The LT-SOFC with the bilayer Ni anode cell achieved the best performance, 201 mW/cm 2 at 500 °C. Electrochemical impedance spectroscopy analysis was conducted to reveal detailed behaviors of AAO based LT-SOFCs. Therefore, we successfully optimized the anode structure for high performance AAO template based LT-SOFCs.