http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
Lim, Sangyeob,Shin, Chansun,Heo, Jungwoo,Kim, Sangeun,Jin, Hyung-Ha,Kwon, Junhyun,Guim, Hwanuk,Jang, Dongchan Elsevier 2018 JOURNAL OF NUCLEAR MATERIALS Vol.503 No.-
<P><B>Abstract</B></P> <P>HT9, a ferritic/martensitic steel, is a candidate structural material for next-generation advanced reactors. Its microstructure is a typical tempered martensite showing a hierarchical lath-block-and-packet structure. We investigate the specimen size effect and strengthening contribution of various microstructural boundaries manifested in the compression tests of micropillars with diameters ranging from 0.5 to 17 μm. It is observed that micropillars with diameters larger than 3 μm show uniform deformation and plastic flow curves comparable to the bulk flow curve. Localized deformation by a few pronounced slip bands occurs in micropillars with diameters smaller than 1 μm, and the yield strength is reduced. Careful examination of the sizes of the microstructural features and cross-sections of the micropillars shows that the block boundaries are the most effective strengthening boundaries in tempered martensitic microstructure. The bulk mechanical properties of HT9 can be evaluated from a micropillar with diameter as low as 3 μm.</P>
Jin, Hyung-Ha,Lim, Sangyeob,Kwon, Junhyun Elsevier 2017 Nuclear instruments & methods in physics research. Vol.409 No.-
<P><B>Abstract</B></P> <P>Microstructural changes in austenitic stainless steel caused by hydrogen ion irradiation were investigated using transmission electron microscopy (TEM). It has been confirmed that the irradiation induced the formation of martensite along the grain boundary; the martensite phase exhibited a crystal orientation relationship with the adjacent austenite phase. The results of this study also indicate that the concentration of Cr in the martensite phase is lower compared to that in the austenite matrix. The TEM results showed the development of asymmetric radiation-induced segregation (RIS) near the grain boundary, which leads to local changes in the chemical composition such as reduction of Cr near the grain boundary. The asymmetric RIS serves as a prerequisite for the formation of the martensite under hydrogen irradiation.</P>
Sung‑Soo Kim,Sangyeob Lim,Dong‑Hyun Ahn,Gyeong‑Geun Lee,Kunok Chang 대한금속·재료학회 2019 METALS AND MATERIALS International Vol.25 No.4
We analyzed the microstructural characteristics such as number density and length and width of hydrides in Zr–2.5 wt%Nbpressure tube. The hydrogen was charged cathodically and the hydride-contained sample was evaluated using the advancedanalysis methodologies. We performed a diff erential scanning calorimetry analysis to more quantitatively understand thethermodynamics of the hydride formation/growth process. We characterized the micrograph of hydride-contained Zr samplesto estimate the microstructural characteristics of the matrix and hydrides. We investigated eff ects of hydrogen concentrationand microstructure of matrix on determining microstructural measures of the hydrides. Particularly, we found that β phasein the matrix becomes isolated during the heat treatment same or above 475 °C and this change increases the inhomogeneousnucleation sites signifi cantly. We claim that the microstructure change of this matrix phase greatly increases the numberdensity of hydride.
Study on the mechanical properties and microstructure of Zr-2.5wt%Nb pressure tube material
Ahn, Dong-Hyun,Lim, Sangyeob,Lee, Gyeong-Geun,Chun, Young-Bum Elsevier 2019 JOURNAL OF NUCLEAR MATERIALS Vol.523 No.-
<P><B>Abstract</B></P> <P>In order to study the mechanical properties and the anisotropy of a Zr-2.5 wt%Nb pressure tube material, tensile tests along the principal tube directions, which are axial, transverse and radial, were performed at room temperature using a pressure tube. The effect of tube length was evaluated, by using samples from the tube's back-end, middle, and front-end. Strong anisotropy among the principal directions was found, and increased strengths were obtained with increased distance from the front-end location. Microstructure analysis by X-ray diffraction, electron backscatter diffraction, and scanning electron microscopy indicated that increasing defect density along the tube was the main reason for the increasing strength. Although texture mainly determined the anisotropy of the tensile strengths, the ratio between the axial and radial strengths could be considerably altered by hydride plates. Depending on how the hydride plate was placed with regard to the deformation direction, the yield strength and strain hardening ability were reduced differently by the hydride. The deterioration effect of the hydrides did not show linear dependency on the hydrogen contents due to other microstructure variations. We had a brief discussion about which parameters might result in the non-linear change found in the deterioration along the tube.</P>
Jin, Hyung-Ha,Ko, Eunsol,Lim, Sangyeob,Kwon, Junhyun,Shin, Chansun ELSEVIER 2017 JOURNAL OF NUCLEAR MATERIALS Vol.493 No.-
<P><B>Abstract</B></P> <P>We investigated the microstructural and hardness changes in austenitic stainless steel after Fe ion irradiation at 400, 300, and 200 °C using transmission electron microscopy (TEM) and nanoindentation. The size of the Frank loops increased and the density decreased with increasing irradiation temperature. Radiation-induced segregation (RIS) was detected across high-angle grain boundaries, and the degree of RIS increases with increasing irradiation temperature. Ni–Si clusters were observed using high-resolution TEM in the sample irradiated at 400 °C. The results of this work are compared with the literature data of self-ion and proton irradiation at comparable temperatures and damage levels on stainless steels with a similar material composition with this study. Despite the differences in dose rate, alloy composition and incident ion energy, the irradiation temperature dependence of RIS and the size and density of radiation defects followed the same trends, and were very comparable in magnitude.</P>
Ji Hee Han,Hyeong Gyeong Kim,Hun Tae Lim,Jeong Jun Kim,SangYeob Lee 한국응용곤충학회 2013 한국응용곤충학회 학술대회논문집 Vol.2013 No.10
Beet armyworm, Spodoptera exigua are difficult to control using chemical insecticides because of the development of insecticide resistance. For eco-friendly beet armyworm managements, various control agents are required. Entomopathogenic fungus is one of promise control agents as an alternative to chemical control agent. We isolated entomopathogenic fungi from soil samples of suwon by insect-bait method using Galleria mellonella and conducted bioassay to larva of beet armyworm. As a result of bioassay isolate FG274, FG340, FG344 had high virulence as 100% against second instar larva of S. exigua. To identify the fungus isolates, their’s morphological characteristic was observed and ITS of 18srRNA was sequenced. ITS sequence of FT274, 340, 344 were highly matched (100%) to that of Beauveria bassiana, Paecilomyces fumosoroseus, Metarhizium anisopliae. To investigate the optimal concentration, three isolates were sprayed at three different concentration(1×106 ,107 and 108 conidia/㎖) in laboratory conditions. 나타내었다.
Mechanistic insights into lead-accelerated stress corrosion cracking of Alloy 600
Hur, Do Haeng,Choi, Won-Ik,Song, Geun Dong,Jeon, Soon-Hyeok,Lim, Sangyeob Elsevier 2018 Corrosion science Vol.145 No.-
<P><B>Abstract</B></P> <P>The purpose of this work is to provide insights into the lead-accelerated stress corrosion cracking mechanisms of Alloy 600 from the perspective of the electrochemical role of lead. Lead-species were electrochemically reduced at the oxide/matrix interface, which increased the dissolution rate of the alloy elements (preferentially Cr) from and oxidation of the matrix. These electrochemical processes resulted in the fast formation of defective thick oxides with a relatively lower Cr content, which provide paths for the migration of lead-species toward the interface. Finally, the mechanistic model of fast cracking by lead contamination is described.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Pb-species is electrochemically reduced to metallic Pb at the oxide/matrix interface. </LI> <LI> The fraction of metallic Pb incorporated in oxides increases toward the interface. </LI> <LI> The dissolution of the matrix is stimulated by the reduction to metallic Pb. </LI> <LI> The accelerated corrosion process induces the formation of defective thick oxides. </LI> </UL> </P>