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김윤재,정우영,이동훈,Yoon-Jae Kim,Woo-Young Jung,Dong-Hoon Lee 대한핵의학기술학회 2023 핵의학 기술 Vol.27 No.1
Purpose The long-term trend of extrinsic uniformity by type of gamma camera was analyzed, and the factors affecting uniformity were investigated. Based on this, the purpose was to predict the life of the gamma camera, pay attention to factors that affect uniformity, and obtain better quality images. Materials and methods Four of the gamma cameras in operation at a senior general hospital in Seoul were selected and the trend of extrinsic uniformity from the first operation date to the present was analyzed. In order to minimize various factors affecting uniformity, a detailed analysis was conducted by calculating the monthly and annual average of the uniformity values. Results Two Symbia E gamma cameras from SIEMENS, one Symbia Evo Excel gamma camera, and one Symbia Intevo16 gamma camera were selected and analyzed. The uniformity of Symbia E<sub>1</sub> (2012 warehousing) changed unevenly, and the uniformity of Symbia E<sub>2</sub> (2014 warehousing) changed according to the replacement cycle of <sup>57</sup>Co sheet sources. The uniformity of Symbia Evo Excel (received in 2017) and Symbia Intevo 16 (received in 2017) was constant compared to Symbia E. Conclusion The extrinsic uniformity of the gamma camera gradually increased over time. However, there was a difference in uniformity for each type of gamma camera, and there was a change in uniformity in which the cause could not be accurately identified. In order to improve the quality of the image, it is necessary to periodically check changes in uniformity and minimize factors that affect uniformity.
스트레스 조건에 노출된 Angelfish Pterophyllum scalare의 행동 변화 분석 및 예측
김윤재 ( Yoon-jae Kim ),노혜민 ( Hea-min No ),김도형 ( Do-hyung Kim ) 한국수산과학회 2021 한국수산과학회지 Vol.54 No.6
The behavior of angelfish Pterophyllum scalare exposed to low and high temperatures was monitored by video tracking, and information such as the initial speed, changes in speed, and locations of the fish in the tank were analyzed. The water temperature was raised from 26℃ to 36℃ or lowered from 26℃ to 16℃ for 4 h. The control group was maintained at 26℃ for 8 h. The experiment was repeated five times for each group. Machine learning analysis comprising a long short-term memory model was used to train and test the behavioral data (80 s) after pre-processing. Results showed that when the water temperature changed to 36℃ or 16℃, the average speed, changes in speed and fractal dimension value were significantly lower than those in the control group. Machine learning analysis revealed that the accuracy of 80-s video footage data was 87.4%. The machine learning used in this study could distinguish between the optimal temperature group and changing temperature groups with specificity and sensitivity percentages of 86.9% and 87.4%, respectively. Therefore, video tracking technology can be used to effectively analyze fish behavior. In addition, it can be used as an early warning system for fish health in aquariums and fish farms.
현대사회의 영상물의 새로운 조건과 영상에 대한 새로운 정의에 대한 연구
김윤재(Kim Yoon-Jae) 한국문화산업학회 2004 문화산업연구 Vol.4 No.2
Our views on things are closely associated with what we know or believe. Recent possibility to reproduce works of art has changed popular attitude towards arts. For the reason, there have been a lot of discussions about a new definition of arts. In his "Image Communication and Society", John Burger discusses problems of images involved with social communication in present-day society focusing on the process of accepting images in arts. This article is intended to examine discussions about images based on John Berger's "Image and Image Language", and discuss new conditions and definition of images in contemporary society. Our views on things are closely associated with what we know or believe. Recent possibility to reproduce works of art has changed popular attitude towards arts. For the reason, there have been a lot of discussions about a new definition of arts. In his "Image Communication and Society", John Burger discusses problems of images involved with social communication in present-day society focusing on the process of accepting images in arts. This article is intended to examine discussions about images based on John Berger's "Image and Image Language", and discuss new conditions and definition of images in contemporary society.
다공성 재료의 물리적 성질의 흡음률에 대한 영향 및 물리적 성질추정
김윤재(Yoon Jae Kim),강연준(Yeon June Kang),김정수(Jung Soo Kim),맹주영(Joo Young Maeng),윤형준(Hyung June Youn) 한국자동차공학회 2005 한국자동차공학회 춘 추계 학술대회 논문집 Vol.2005 No.5_2
The performance of acoustical materials is determined by their macroscopic physical parameters. However, these parameters are difficult to measure accurately, in some cases. The influence of each parameter on the normal incidence absorption coefficient and surface impedance was studied to estimate the properties of acoustical materials. This paper is focused on the procedure of properties estimation of porous materials by numerical method.
김윤재(Yoon Jae Kim),백상민(Sang Min Baek),오원석(Won Seok Oh),고정인(Jeong In Go) 한국항공우주학회 2019 韓國航空宇宙學會誌 Vol.47 No.12
본 논문에서는 하이브리드 복합재를 전자기학적 성능을 단순화하여 설계하는 방법을 제안한다. 제안 방법은 전통적인 간단한 이론들을 바탕으로 하며 최적 설계 등과 같은 기존 하이브리드 복합재의 설계 방법들에 비하여 간단하다. 따라서, 실제적인 문제에 대하여 보다 쉽게 적용할 수 있다. 본 논문은 등가 유전율 및 다층 유전체에서의 전파 전송 이론을 이용한다. 우선, 설계 영역을 전자기학적 기능에 따라 몇 개의 영역으로 구분하고 각 영역을 등가 유전율로 표현하였다. 입사각 안정성과 투과 성능을 고려하여 가능한 유전율 조합을 산출하고 몇 번의 전자기 성능 해석을 통하여 기본 설계 형상을 도출하였다. 제안한 설계 방법의 타당성을 간접적으로 확인하기 최종 설계안에 대한 전파투과시험을 수행하였다. This paper represents an simplified design method of hybrid composites. The proposed method is very simple compared to conventional design approaches and easy to apply to practical design problems. The method is based on not complex optimization approaches but conventional theories. The equivalent dielectric properties concept and multi-layered dielectric slab theory are an important theoretical background of the proposed method. This approach divide the design domain into several domain which have theoretically different electro- agnetic functionality. Then, the domains are expressed by equivalent dielectric properties. Numerical analysis are performed several types of design candidates. S-parameter test for final design was conducted for validate the proposed approach indirectly.
김윤재(Yoon-Jae Kim),박동희(Dong-Hee Park),황용석(Yong-Seok Hwang) 한국생산제조학회 2004 한국공작기계학회 춘계학술대회논문집 Vol.2004 No.-
A ion source using inductively coupled plasma has been tested in order to test its feasibility as a high brightness ion source for focused ion beam. When operating the ion source with filter magnets in front of plasma electrode for a negative ion source, lower emittances are expected. Extracted beam emittances are measured with an Allison-type scanning device for various plasma parameters and extraction conditions. The normalized emittance has been measured to be around 0.2 πmmmrad with beam currents of up to 0.55 ㎃. In particular, noting that multicusp magnets have a role in decreasing the emittance as well as increasing plasma discharge efficiency, transverse magnetic field has been confirmed to be a useful tool for decreasing emittance via electron energy control.