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조영숙,박석규,박정로,김종홍,이종일,문주석 순천대학교 기초과학연구소 1993 基礎科學硏究誌 Vol.4 No.-
Tubers of Korean yams were analyzed in proximate, amino acid and fatty acid compositions. The yams were composed of moisture (70.6-86.1%), protein (5.8-9.2%), crude fat (0.2-0.9%) and reducing sugar (0.7-2.9%). The pH and titratable acidity of yam juice were 6.0-6.3 and 0.9-1.1 ㎎%, respectively. Total amino acid contents of the yams were 21.2-26.9% comprising essential amino acids of 49.2-57.3%, and the major amino acids were glutamic acid (2.9-4.3%), arginine (3.0-4.2%) and aspartic acid (2.2-2.8%). Thirteen fatty acids were detected, and the major fatty acids were linoleic (42.2-49.4%), palmitic (25.5-27.8%) and oleic acid (4.7-13.7%).
Jeong, Ill-Seok,Kim, Wan-Jae,Kim, Tae-Ryong,Jeon, Hyun-Ik Korean Nuclear Society 2011 Nuclear Engineering and Technology Vol.43 No.1
To define the effect of strain rate variation from 0.04% to 0.004%/s on environmental fatigue of CF8M cast stainless steel, which is used as a primary piping material in nuclear power plants, low-cycle fatigue tests were conducted at operating pressure and temperature condition of a pressurized water reactor, 15 MPa and $315^{\circ}C$, respectively. A high-pressure and high-temperature autoclave and cylindrical solid fatigue specimens were used for the strain-controlled low-cycle environmental fatigue tests. It was observed that the fatigue life of CF8M stainless steel is shortened as the strain rate decreases. Due to the effect of test temperature, the fatigue data of NUREG-6909 appears a slightly shorter than that obtained by KEPRI at the same stress amplitude of $1{\times}10^3$ MPa. The environmental fatigue correction factor $F_{en}$'s calculated with inputs of the test data increases with high strain amplitude, while the $F_{en}$'s of NUREG-6909 remain constant regardless of strain amplitude.
STRAIN RATE CHANGE FROM 0.04 TO 0.004%/S IN ANENVIRONMENTAL FATIGUE TEST OF CF8M CASTSTAINLESS STEEL
ILL-SEOK JEONG,WANJAE KIM,김태룡,HYUN-IK JEON 한국원자력학회 2011 Nuclear Engineering and Technology Vol.43 No.1
To define the effect of strain rate variation from 0.04% to 0.004%/s on environmental fatigue of CF8M cast stainlesssteel, which is used as a primary piping material in nuclear power plants, low-cycle fatigue tests were conducted at operatingpressure and temperature condition of a pressurized water reactor, 15 MPa and 315ºC, respectively. A high-pressure andhigh-temperature autoclave and cylindrical solid fatigue specimens were used for the strain-controlled low-cycle environmentalfatigue tests. It was observed that the fatigue life of CF8M stainless steel is shortened as the strain rate decreases. Due to theeffect of test temperature, the fatigue data of NUREG-6909 appears a slightly shorter than that obtained by KEPRI at thesame stress amplitude of 1x103MPa. The environmental fatigue correction factor Fen’s calculated with inputs of the test dataincreases with high strain amplitude, while the Fen’s of NUREG-6909 remain constant regardless of strain amplitude.
Environmental Fatigue Crack Propagation Behavior of Cast Stainless Steels under PWR Condition
Jeong, Ill Seok,Kim, Sang Jai,Song, Taek Ho,Kwon, Jong Jooh,Hong, Sung Yul,Cho, Sun Young Trans Tech Publications, Ltd. 2005 Key Engineering Materials Vol.297 No.-
<P>Environmental fatigue crack propagation of CF8M and CF8A steels used in the domestic nuclear power plants (NPPs) were investigated on the simulated pressurized water reactor (PWR) condition (temperature: 316°C, pressure: 15MPa). The test equipment for environmental fatigue (high temperature-high pressure loop, autoclave, load frame, and measurement system) was designed. As-received and 60-year aged specimens were used in the test. To compare with environmental fatigue test, another test in the air condition was performed. The fracture surfaces of specimens were difficult to verify the fracture modes such as striation, inter-granular crack and cleavage and so on. As the ferrite content of CF8M is increased, more particles on the fracture surface were peeled.</P>
변형률속도가 CF8M CASS 환경피로 수명에 미치는 영향 평가
정일석(Ill-Seok Jeong),하각현(Gak-Hyun Ha),전현익(Hyun-Ik Jeon) 대한기계학회 2009 대한기계학회 춘추학술대회 Vol.2009 No.5
The Environmental fatigue life of CF8M cast stainless steel is influenced by mechanical, environmental and metallurgical parameters, such as strain rate, strain amplitude, temperature, dissolved oxygen concentration, water flow rate and so on. In an actual plant, the mechanical and environmental parameters are changing during the plant operation. Therefore, the effect of such mechanical and environmental parameter changes on fatigue life evaluation have to be studied. Low cycle fatigue life of structural materials diminishes remarkably as functions of various parameters in high temperature and high pressure environments. Such reduction can be estimated by the fatigue life reduction factor(Fen). In this study, fatigue tests were performed under changing conditions of strain amplitude, strain rate. Fatigue life was measured in terms of the number of cycles with the variation of strain amplitudes at 0.004 %/s strain rate, and the fatigue life correction factor was evaluated according to the equation modified by U. S. Nuclear Regulatory Commission(U.S.NRC) and Japanese Environmental Fatigue Tests committee(JEFT).
정일석(Ill-Seok Jeong),김상재(Sang-Jai),홍승열(Sung-Yull Hong) 대한기계학회 2005 대한기계학회 춘추학술대회 Vol.2005 No.8
Among published environmental fatigue test data of stainless steels, Type 304 SS, Type 316 SS, Type 316N SS, Type 316 Weld SS, and cast stainless steel CF8M in Japan and U.S., useful data were quoted for analyzing the effect of sensitizing stainless steels in LWR environments. Temperature of the test data are 288~325℃ which is operating temperature range of LWR plants. Data were classified in terms of dissolved oxygen levels, strain rates in tension stroke, and sensitization. Then data were compared with logarithmic graph of vertical strain rate and horizontal fatigue life. Trend of sensitization was investigated for each type of stainless steels.
정일석(Ill-Seok Jeong),김상재(Sang-Jai Kim),홍승열(Sung-Yull Hong) 대한기계학회 2005 대한기계학회 춘추학술대회 Vol.2005 No.11
Among published environmental fatigue test data of stainless steels, Type 304 SS, Type 316 SS, Type 316N SS, Type 316 Weld SS, and cast stainless steel CF8M in Japan and U.S., useful data were quoted for analyzing the effect of sensitizing stainless steels in LWR environments. Temperature of the test data are 288~325℃ which is operating temperature range of LWR plants. Data were classified in terms of dissolved oxygen levels, strain rates in tension stroke, and sensitization. Then data were compared with logarithmic graph of vertical strain rate and horizontal fatigue life. Trend of sensitization was investigated for each type of stainless steels.
CF8M 스테인리스 강 저주기 환경피로 실험의 주기적 변형률 경화 특성
정일석(Ill-Seok Jeong),하각현(Gak-hyun Ha),김태룡(Tae-Ryong Kim),전현익(Hyun-Ik Jeon),김영신 대한기계학회 2007 대한기계학회 춘추학술대회 Vol.2007 No.5
Low-cycle environmental fatigue tests of cast austenitic stainless steel CF8M at the condition of fatigue strain rate 0.04%/sec were conducted at the pressure and temperature, 15MPa, 315℃ of a operating pressurized water reactor. The used test rig was limited to install an extensometer at the gauge length of the cylindrical fatigue specimen inside the small autoclave. So the magnet type LVDT’s were used to measure the fatigue displacement at the specimen shoulders inside the high temperature and high pressure water autoclave. However, the displacement and strain measured at the specimen shoulders is different from the one at the gauge length for the geometry and the cyclic strain hardening effect. FEM calculated the displacement and the strain of the gauge length from the data measured at the shoulders. Tensile test properties in elastic and plastic behavior of CF8M material were used in the FEM analysis. A series of low cycle fatigue tests simulating the cyclic strain hardening effect verified that the FEM calculation was well agreed with the simulated tests. The process and method developed in this study would be so useful to produce reliable environmental fatigue curves of CF8M stainless steel in pressurized water reactors.
고온고압 환경피로실험 오토클래이브 내부용 미소변위 측정장치 개발
정일석(Ill-Seok Jeong),하각현(Gak-hyun Ha),김태룡(Tae-Ryong Kim),전현익(Hyun-Ik Jeon),김영신(Young-Sin Kim) 대한기계학회 2008 대한기계학회 춘추학술대회 Vol.2008 No.11
An extensometer system to measure strain and displacement of cylindrical fatigue specimen in a autoclave of high temperature and high pressure environment has been developed by KEPRI. The extensometer reads the displacement caused by fatigue loads at the target length of the specimen installed inside the autoclave. The performance of the extensometer were tested at 15㎫, 315℃of a operating pressurized water reactor. Two LVDT’s of magnet type were connected to the extensometer and used for converting the fatigue displacement to electronic signal. The device is being used for developing environmental fatigue curve of CF8M cast austenitic stainless steel (CASS) in the test condition of low cycle and low strain. This paper introduces the background and results of the development.