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돼지설사 원인균 E. coli의 생육저해에 대한 유산균의 효과
姜國熙,成文喜,方泰瑛,龍球淵,林讚洙 成均館大學校 科學技術硏究所 1985 論文集 Vol.36 No.1
E. coli A_2 diarrhea causing bacteria of pigs was anaerobically inoculated with 10^5/ml into prereduced YS medium (10% reconstituted skim milk+0.1% yeast extract), and then lactic acid bacteria were inoculated with 10^5/ml and 10^7ml into previous inoculated samples of E. coli A_2. Inoculated samples cultured at 37℃, were tested to determine changes in viable numbers of organisms and pH. The experimental results are summerized as follows: 1. In the mixed culture medium of 10^5/ml E. coli A_2 and L. casei YIT9018, E. coli A_2 decreased after 36 hours from incubation. 2. In the mixed culture medium of 10^5/ml E. coli A_2 and L. acidophilus, E. coli A_2 drastically decreased after 24 hours from incubation and was almost disappeared after 72 hours from incubation. 3. In the mixed culture medium of 10^5/ml E. coli A_2 and L. bulgaricus, E. coif A_2 drastically decreased after 24 hours from incubation and was almost disappeared after 72 hours from incubation. 4. In the mixed culture medium of 10^5/ml E. coli A_2 and Str. thermophilus, E. coli A_2 decreased after 12 hours from incubation. 5. When the pH value of the mixed culture, was, 4. 5 below, E. coli A_2 decreased.
열처리 상태가 10Cr-1Mo-VNbN 주강의 기계적 성질 및 용접성에 미치는 영향
손대영,방국수,이경운,지병하 대한금속재료학회 2003 대한금속·재료학회지 Vol.41 No.11
Mechanical properties and weldability such as HAZ hardness, cold cracking susceptibility and hot ductility of two differently heat treated 10Cr-1Mo-VNbN cast steels were measured and compared. Because of high hardenability of the cast steel, as-annealed cast steel showed martensitic microstructure and thus had higher hardness than annealed-normalized-tempered cast steel which had tempered martensite. Because the welding electrode used resulted in a high hardness weld metal, both cast steels showed same weld metal cold cracking susceptibility even though the as-annealed cast steel had higher HAZ hardness than the annealed-normalizedtempered cast steel. Both cast steels had excellent hot ductility in high temperature range, indicating no risk of grain boundary liquation cracking in the HAZ. However, the as-annealed cast steel showed an inferior ductility in the intermediate temperature range of 1000~1150℃ because of larger unrecrystallized grain size.
Low Heat Input Welding to Improve Impact Touglness of Multipass FCAW-S Weld Metal
Kook-soo Bang,Chan Park,Ho-shin Jeong 한국해양공학회 2014 韓國海洋工學會誌 Vol.28 No.6
Multipass self-shielded flux cored arc welding with different heat inputs (1.3-2.0 kJ/㎜) was conducted to determine the effects of the heat input on the proportion of the reheated region, impact toughness, and diffusible hydrogen content in the weld metal. The reheated region showed twice the impact toughness of the as-deposited region because of its fine grained ferritic-pearlitic microstructure. With decreasing heat input, the proportion of the reheated region in the weld metal became higher, even if the depth of the region became shallower. Accordingly, the greatest impact toughness, 69 J at -40℃, was obtained for the lowest heat input welding, 1.3 kJ/㎜. Irrespective of the heat input, little difference was observed in the hardness and diffusible hydrogen content in the weld metal. This result implies that low heat input welding with 1.3 kJ/㎜ can be performed to obtain a higher proportion of reheated region and thus greater impact toughness for the weld metal without the concern of hydrogen cracking.
Clinical Features of Waldenstrom Macroglobulinemia in Korea
( Soo Mee Bang ),( Sook Ryun Park ),( Se Hoon Park ),( Eun Kyung Cho ),( Sung Soo Yoon ),( Dong Bok Shin ),( Jae Hoon Lee ),( Seon Yang Park ),( Byoung Kook Kim ),( Noe Kyeong Kim ) 대한내과학회 2004 The Korean Journal of Internal Medicine Vol.19 No.3
다층용접한 저합금 용접금속의 강도와 인성에 미치는 입열량 및 예열/패스간 온도의 영향
방국수(Kook-soo Bang),정호신(Ho-shin Jung),박찬(Chan Park) 한국해양공학회 2015 韓國海洋工學會誌 Vol.29 No.6
The effects of the heat input and preheat/interpass temperatures on the tensile strength and impact toughness of multipass welded weld metal were investigated and interpreted in terms of the recovery of the alloying elements and microstructure. Increases in both the heat input and preheat/interpass temperatures decreased the tensile strength of the weld metal. A lower recovery of alloying elements, especially Mn and Si, and smaller area fraction of acicular ferrite in the weld metal were observed in higher heat input welding, resulting in a lower tensile strength. In contrast, only a microstructure difference was observed at a higher preheat/interpass temperature. The impact toughness of the weld metal gradually increased with an increase in the heat input because of the lower tensile strength. However, it decreased again when the heat input was larger than 45 kJ/cm because of the much smaller area fraction of acicular ferrite. No effect of the preheat/interpass temperature on the impact toughness was observed. The formation of a weld metal heat-affect zone showed little effect on the impact toughness of the weld metal in this experiment.
발전용 저탄소 ASTM A356 CA6NM 마르텐사이트계 스테인리스 주강의 용접성
방국수 ( Kook Soo Bang ),박찬 ( Chan Park ),이주영 ( Jong Young Lee ),이경운 ( Kyong Woon Lee ) 대한금속재료학회(구 대한금속학회) 2011 대한금속·재료학회지 Vol.49 No.1
Weldability, especially HAZ cold cracking, weld metal solidification cracking, and HAZ liquation cracking susceptibilities, of ASTM A356 CA6NM martensitic stainless steel casting was investigated and compared with that of 9-12% Cr ferritic steel castings. Irrespective of the Cr and Ni content in the castings, the HAZ maximum hardness increased with an increase of carbon content. CA6NM steel, which has the lowest carbon content, had the lowest HAZ hardness and showed no cold cracking in y-slit cracking tests. CA6NM steel, meanwhile, showed the largest weld metal solidification cracking susceptibility in varestraint tests because of its higher amount of impurity elements, phosphorus, and sulfur. All castings investigated had good high temperature ductility in hot ductility tests and showed little difference in liquation cracking susceptibility.
셀프실드아크 용접금속의 확산성수소량에 미치는 용접변수의 영향
방국수(Kook-Soo Bang),박찬(Chan Park) 한국해양공학회 2013 韓國海洋工學會誌 Vol.27 No.5
The effects of the welding parameters, contact tip-to-workpiece distance (CIWD), current, and voltage on the diffusibel hydrogen content in weld metal deposited by self-shielded flux, cored are welding were investigated and rationalized by comparing the amount of heat generated in the extension length of the wire. This showed that as CTWD increased from 15mm to 25mm, the amount of heat generated was increased from 71.7J to 174.8J, and the hydrogen content was decreased from 11.3mL/100g to 5.9mL/100 g. Even if little difference was observed in the amount of heat generated, the hydrogen content was increased with an increase in voltage because of the longer arc length. A regression analysis showed that the regression coefficient of voltage in self-shielded flux cored arc welding is greater than that in CO₂ arc welding. This implies that voltage control is more important in self-shielded flux cored arc welding than in CO₂ arc welding.
저 탄소형 Ti-B 첨가강 강도와 인성에 미치는 B 의 영향 (1) : 모재의 강도와 인성 Strength and Toughness of Base Metal
방국수,안영호 대한금속재료학회(대한금속학회) 1996 대한금속·재료학회지 Vol.34 No.1
Based on the thermodynamic model between TiN-BN-AlN in austenite, the effect of the boron content of direct-quenched low-carbon type Ti-B containing steels on the tensile strength and impact toughness was investigated. Variation of tensile strength showed a good relationship with the calculated soluble boron content at the start cooling temperature, showing that the thermodynamic model was applicable to the prediction of the hardenability of direct-quenched Ti-B containing steels. Impact toughness was varied form 20J to 250J at -40℃, depending on microstructure which was determined by the soluble boron content and the cooling rate. The highest absorbed energy of 200∼250J was obtained at martensite and lower-bainite mixed microstructure, followed by 100∼200J at ferrite and bainite mixed microstructure and 20∼40J at bainite with martensite-austenite constituent microstructure.
Proposed Performance Criteria and Evaluation Procedures for Transmission System Planning in Korea
Kook, Kyung-Soo,Kim, Taihyun,Oh, Tae-Kyoo,Bang, Min-Jae The Korean Institute of Electrical Engineers 2002 KIEE International Transactions on Power Engineeri Vol.a2 No.4
This paper describes a proposed performance criteria and evaluation procedures for transmission system planning in Korea. Performance criteria of the transmission system are expected to be used as a guideline for investment into a transmission network. Moreover, performance evaluation procedures, which are based on current practices and widely accepted theories, are suggested to achieve fair and acceptable results.