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Aging estimation of reactor pressure vessel in the field using magnetic properties
Baek, Un Bong,Ryu, Kwon Sang,Kim, Amkee,Nahm, Seung Hoon Elsevier 2009 Journal of loss prevention in the process industri Vol.22 No.6
<P><B>Abstract</B></P><P>Many researchers have been interested in the nondestructive measurement methods for estimating components damage in order to assure the safe service of steel structures. It is recognized that the evaluating techniques based on magnetic measurement can offer a great potential because of high susceptibility to the change of several metallurgical factors. Magnetic property such as coercive force was measured. The coercive force at room temperature monotonously increased with the increase of frequency. The correlation between the magnetic properties of used material and that of un-used material was studied. The coercive force gradient at room temperature increased with the increase of aging. Hence the estimating method using magnetic properties allows one to evaluate the extent of material aging for reactor pressure vessel.</P>
A Study on Fatigue Properties of Sc Added Al 2519 Alloy
Baek, Un Bong,Park, Jong Seo,Chung, In Hyun,Nahm, Seung Hoon,Ma, Young Hwa,Lee, Yong Yun Trans Tech Publications, Ltd. 2005 Key Engineering Materials Vol.297 No.-
<P>The high cycle fatigue properties of two kinds of wrought Al 2519 alloys without and with scandium of 0.10% were investigated. The fatigue strength was determined at R = 0.1 under constant amplitude loading conditions in air. The alloy with scandium of 0.10% showed a little lower tensile yield strength and higher fatigue strength values. The fine grained Al-0.10Sc alloy exhibited a higher resistance against fatigue crack nucleation despite the lower yield stress in comparison to the coarse grained Al 2519 alloy. The results can be explained mainly with the microstructural differences between both alloys. This results are due to the presence of coherent Al3 (Sc, Zr) precipitates and a very fine subgrain structure.</P>
Baek, Seung-Wook,Song, Eun Ju,Kim, Jung Hyun,Jung, Myungsik,Baek, Un Bong,Nahm, Seung Hoon Elsevier 2017 Scripta materialia Vol.130 No.-
<P><B>Abstract</B></P> <P>Metal additive manufacturing (AM) technology as the emerging future manufacturing technology can be applied to the hydrogen service including hydrogen energy utilized industry. Direct metal tooling (DMT), one of the 3-D printing technologies, was used to manufacture an austenitic stainless steel part, and its mechanical properties and hydrogen embrittlement (HE) behavior were studied using the small specimen test technique under 10-MPa pressurized hydrogen gas. This part showed high HE resistance with minimal strain-induced transformation of austenite to martensite. This result indicates that parts produced using DMT are suitable for use in facilities for hydrogen service and hydrogen infrastructure.</P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>
Magnetic Shielding Effect on Halbach Cylinder used in Magnetic Refrigerators
Un Bong Baek,Jong Suk Lee,Seong-Cho Yu,Kwon-Sang Ryu 한국자기학회 2014 Journal of Magnetics Vol.19 No.4
The system for producing magnetic field constitutes an important component of magnetic refrigerator. Many researchers have directed significant effort to increase the magnetic field intensity, because the magnetocaloric effect at the Curie temperature increases with the power of 2/3 of the magnetic field. In this study, we report the simulation of the magnetic field intensity at polar axis of a Halbach cylinder (HC) by i) changing the length and thickness of the HC, ii) having with or without gap of the HC, and iii) surrounding the HC with a soft magnet shell, acting as a shielding. We simulated the field distribution of a HC with a finite size. Furthermore, the detailed numerical results of the magnetic field distribution and its dependence on shielding are presented in this study.
백민혁(Baek Min Hyuck),김재훈(Kim Jae Hoo),백운봉(Baek Un Bong),이해무(Lee Hae Moo),강전일(Kang Jeon Il) 대한기계학회 2010 대한기계학회 춘추학술대회 Vol.2010 No.11
In this study, Strain controled fatigue properties were experimentally measured for 9Cr-1Mo crossweld steel. This test data will using design and life assessment for fossil power plant boiler head and steam pipes. Strain controled fatigue test performed at room temperature and high temperature (design temperature). Temperature effect for low cycle fatigue is discussed in detail. The microstructure according to the room temperature and 538 ℃ are discussed.
백운봉(Un Bong Baek),이윤희(Yun-Hee Lee),이해무(Hae Moo Lee),유권상(Kyun Sang Ryu),정인현(In-Hyun Jung),박종서(Jong-Suh Park),남승훈(Seung Hoon Nahm),신형섭(Hyung Sup Shin) 대한기계학회 2010 대한기계학회 춘추학술대회 Vol.2010 No.11
An important part of the ongoing preparation toward the hydrogen economy is to validate the existing and proposed materials for reliable and safe storage, transport, and distribution of hydrogen gas. The Materials measurement center at KRISS runs a research program that focuses on measuring the material properties of metallic material in a gaseous hydrogen environment. This effort will help determine the susceptibility of existing and high pressure hydrogen tank steels to hydrogen embrittlement and hydrogen-assisted crack growth in gaseous hydrogen.
백운봉(Baek Un Bong),이해무(Lee Hae Moo),이윤희(Lee Yun Hee),남승훈(Nahm Seung Hoon) 대한기계학회 2009 대한기계학회 춘추학술대회 Vol.2009 No.5
In this study. Low cycle fatigue properties were experimentally measured for 9Cr-1Mo steel. This test data will using design and life assessment for fossile power plant boiler head and steam pipes. Low cycle fatigue test performed at room temperature and high temperature(design temperature). Temperature effect for low cycle fatigue is discussed in detail. Standardization performed that the temperature calibration method for high temperature low cycle fatigue. The measured Reversals to failure vs true strain amplitude curve for the 9Cr-lMo steel at room temperature as shown in Fig. 1.