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김은경 ( Eun-gyeong Kim ),김민경 ( Min-kyung Kim ),권현애 ( Hyun-ae Kwon ),윤도경 ( Do-kyung Youn ),구정헌 ( Jeong-heon Koo ),박소연 ( So-yeon Park ),이희근 ( Hui-geun Lee ),조명희 ( Myeong-hui Jo ),하도윤 ( Do-yun Hah ),김철호 ( 한국동물위생학회(구 한국가축위생학회) 2018 韓國家畜衛生學會誌 Vol.41 No.3
Salmonella Enteritidis (S. Enteritidis) are found in animals, humans, and environment. In addition, S. Enteritidis draws attention to the public health concerns due to carriage of antibiotic resistance traits. For these reasons, the prevalence and antibiotic resistance patterns of S. Enteritidis are significant issues with regard to public health. To address this issues, a total of 24 strains of S. Enteritidis from 164 samples collected from several slaughterhouses in Gyeong-Nam province in order for antibiotic resistance profiles. Subsequently, we characterized the genotyping by random amplification polymorphic DNA (RAPD)-PCR. As a result, very high level of resistance to protein synthesis inhibition antibiotics and most isolates were susceptible to others. Six random primers were used for RAPD-PCR to reveal genotypes of S. Enteritidis isolates. One of the primer, P1245, generated 147 distinct RAPD-PCR fragments ranging from 400∼3000 bp. The number of RAPD-PCR products ranged from 4 to 8 for this primer. The RAPD-PCR fragments could be placed these strains into 3 subgroups and 2 classes by UPGMA cluster analysis. Interestingly, several S. Enteritidis that isolated from different slaughterhouses showed same genotype. These results showed only limited genetic variation among the isolates, those were grouped into a few different patterns of antibiotic resistance.
김두희,김경근 가톨릭대학산업의학센타 산업의학연구소 1987 韓國의 産業醫學 Vol.26 No.4
This survey was carried out from the 72 male radiotechnologist who are working in several hospitals and local clinics in Taegu city during three months from the first of June to the end of september, 1986. The blood pictures were counted by the Coulter Counter Model S-plus. The mean value of WBC was 6,397±1,489/㎣, is this significantly lower than in rural group (p<0.01). 13 of the 72 subjects (18.1%) were below 5000/㎣ WBC. WBC count of the radiotechnologists is special photograpyhing room was signitificantly lower than that of those who were in computed tomography room and radio-isotope room (p<0.05). The mean value of RBC was 4.71±0.39×?/㎣, it was significantly lower than in rural control group (p<0.05). 29.2 percent of the subjects were below 4.50×?/㎟ The mean value of hemoglobin was 14.8±13.9gm/㎗. 16 of the 72 subjects(22.2%) were below 14㎎/이. The mean value of hematocrit was 42.9±3.96%, it was significantly lower than in rural group (p<0.01). 15 of the 72 subjects(20>8%) were below 40%. The mean value of platelet was 222.1±56.61×10³/㎣, it was significantly lower than in urban group (P<0.02). 30 of the 72 subjects (41.7%) were below 200.0×10³/㎣.
기계학습을 이용한 유동가속부식 모델링: 랜덤 포레스트와 비선형 회귀분석과의 비교
이경근 ( Gyeong-geun Lee ),이은희 ( Eun Hee Lee ),김성우 ( Sung-woo Kim ),김경모 ( Kyung-mo Kim ),김동진 ( Dong-jin Kim ) 한국부식방식학회(구 한국부식학회) 2019 Corrosion Science and Technology Vol.18 No.2
Flow-Accelerated Corrosion (FAC) is a phenomenon in which a protective coating on a metal surface is dissolved by a flow of fluid in a metal pipe, leading to continuous wall-thinning. Recently, many countries have developed computer codes to manage FAC in power plants, and the FAC prediction model in these computer codes plays an important role in predictive performance. Herein, the FAC prediction model was developed by applying a machine learning method and the conventional nonlinear regression method. The random forest, a widely used machine learning technique in predictive modeling led to easy calculation of FAC tendency for five input variables: flow rate, temperature, pH, Cr content, and dissolved oxygen concentration. However, the model showed significant errors in some input conditions, and it was difficult to obtain proper regression results without using additional data points. In contrast, nonlinear regression analysis predicted robust estimation even with relatively insufficient data by assuming an empirical equation and the model showed better predictive power when the interaction between DO and pH was considered. The comparative analysis of this study is believed to provide important insights for developing a more sophisticated FAC prediction model.
최경근 ( Gyeong-geun Choe ),이봉환 ( Bong-hwan Lee ) 한국정보처리학회 2010 한국정보처리학회 학술대회논문집 Vol.17 No.2
클라우드 컴퓨팅 환경에서 사용자들이 사용하는 다양한 어플리케이션은 워크플로우들로 표현된다. 이러한 구조에서의 클라우드 어플리케이션은 워크플로우의 각 작업에 따라 클라우드 서비스가 수행된다. 클라우드 서비스는 동시에 많은 사용자들의 어플리케이션인 다중 워크플로우가 발생되어 워크플로우 내의 작업들이 적절하게 서비스 되어야한다. 따라서, 본 논문에서는 클라우드 컴퓨팅을 고려한 다중 사용자의 워크플로우의 작업 스케줄링 기법을 제안한다.
Lee, Gyeong-Geun,Lee, Yong-Bok,Kwon, Jun-Hyun Korean Nuclear Society 2012 Nuclear Engineering and Technology Vol.44 No.5
The decrease in the fracture toughness of ferritic steels in a reactor pressure vessel is an important factor in determining the lifetime of a nuclear power plant. A surveillance program has been in place in Korea since 1979 to assess the structural integrity of RPV steels. In this work, the surveillance data were collected and analyzed statistically in order to derive the empirical relationship between the embrittlement and strengthening of irradiated reactor pressure vessel steels. There was a linear relationship between the yield strength change and the transition temperature shift change at 41 J due to irradiation. The proportional coefficient was about $0.5^{\circ}C$/MPa in the base metals (plate/forgings). The upper shelf energy decrease ratio was non-linearly proportional to the yield strength change, and most of the data lay along the trend curve of the US results. The transition regime temperature interval, ${\Delta}T_T$, was less than the US data. The overall change from irradiation was very similar to the US results. It is expected that the results of this study will be applied to basic research on the multiscale modeling of the irradiation embrittlement of RPV materials in Korea.
Effect of a sintering process on the electrical properties of SnO2 gas sensors.
Lee, Gyeong-Geun,Kang, Suk-Joong L,Kwon, Junhyun,Kim, Duk Su American Scientific Publishers 2010 Journal of nanoscience and nanotechnology Vol.10 No.1
<P>SnO2 is a widely used sensor material that exhibits high sensitivity. It is known for its complex sensing characteristics, and its microstructure is an important parameter related to electrical properties and mechanical rigidity. Understanding of its microstructural effects is therefore essential to examine sensing mechanisms that may apply to industrial devices. In this work, the effect of a sintering process on the electrical properties is investigated. The sintering temperature and the relative density were chosen as process variables. The grain size of the specimen increased as the sintering temperature increased, whereas the relative density did not change. The apparent activation energy for conduction varied as the compacting pressure and the sintering conditions changed. Samples with a high density and large particle size showed low activation energy for conduction and low sensitivity at 375 degrees C. In an attempt to improve the properties, the powder was heat-treated at 1000 degrees C for 10 hours before compacting and sintering. The samples with heat-treated powder showed a slight decrease in the activation energy depending on the density and comparable sensitivity compared to non-treated powder at a high density. Pre-treatment of powder can be a simple means of thermal stability under high operating temperatures.</P>
초고온가스로 헬륨 분위기에서 Alloy 617의 고온 부식 거동
이경근 ( Gyeong Geun Lee ),정수진 ( Su Jin Jung ),김대종 ( Dae Jong Kim ),정용환 ( Yong Whan Jeong ),김동진 ( Dong Jin Kim ) 대한금속재료학회(구 대한금속학회) 2012 대한금속·재료학회지 Vol.50 No.9
Alloy 617 is a Ni-base superalloy and a candidate material for the intermediate heat exchanger (IHX) of a very high temperature gas reactor (VHTR) which is one of the next generation nuclear reactors under development. The high operating temperature of VHTR enables various applications such as mass production of hydrogen with high energy efficiency. Alloy 617 has good creep resistance and phase stability at high temperatures in an air environment. However, it was reported that the mechanical properties decreased at a high temperature in an impure helium environment. In this study, high-temperature corrosion tests were carried out at 850℃-950℃ in a helium environment containing the impurity gases H2, CO, and CH4, in order to examine the corrosion behavior of Alloy 617. Until 250 h, Alloy 617 specimens showed a parabolic oxidation behavior at all temperatures. The activation energy for oxidation in helium environment was 154 kJ/mol. The SEM and EDS results elucidated a Cr-rich surface oxide layer, Al-rich internal oxides and depletion of grain boundary carbides. The thickness and depths of degraded layers also showed a parabolic relationship with time. A normal grain growth was observed in the Cr-rich surface oxide layer. When corrosion tests were conducted in a pure helium environment, the oxidation was suppressed drastically. It was elucidated that minor impurity gases in the helium would have detrimental effects on the high- temperature corrosion behavior of Alloy 617 for the VHTR application.