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A complementary method to determine the effective flow resistivity of the flat ground states
Sung Soo Jung,Cheol-Ho Hwang 한국물리학회 2004 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.44 No.4
A complementary method to keep a speaker and microphones vertical for determining the sound pressure level dierence was proposed to determine the eective ow resistivities of several ground states. The method could be well applied to at ground and the sound pressure level dierences measured had less scattering than those obtained by using the ordinary method which kept the speaker and the microphones horizontal. The ow resistivity of a cabbage farm was newly estimated as 200 cgs rayls. In the case of a rice plant, we estimated a ow resisitivity of 2 cgs rayls with the new analysis.
Sung, Hwa Jung,Hong, Soon Cheol,Yoo, Ji Hyun,Oh, Jee Hyun,Shin, Hye Jin,Choi, In Young,Ahn, Ki Hoon,Kim, Sun Haeng,Park, Yong,Kim, Byung Soo The Korean Academy of Medical Sciences 2010 JOURNAL OF KOREAN MEDICAL SCIENCE Vol.25 No.10
<P>This study was done to evaluate the stemness of human mesenchymal stem cells (hMSCs) derived from placenta according to the development stage and to compare the results to those from adult bone marrow (BM). Based on the source of hMSCs, three groups were defined: group I included term placentas, group II included first-trimester placentas, and group III included adult BM samples. The stemness was evaluated by the proliferation capacity, immunophenotypic expression, mesoderm differentiation, expression of pluripotency markers including telomerase activity. The cumulative population doubling, indicating the proliferation capacity, was significantly higher in group II (<I>P</I><0.001, 31.7±5.8 vs. 15.7±6.2 with group I, 9.2±4.9 with group III). The pattern of immunophenotypic expression and mesoderm differentiation into adipocytes and osteocytes were similar in all three groups. The expression of pluripotency markers including ALP, SSEA-4, TRA-1-60, TRA-1-81, Oct-4, and telomerase were strongly positive in group II, but very faint positive in the other groups. In conclusions, hMSCs from placentas have different characteristics according to their developmental stage and express mesenchymal stemness potentials similar to those from adult human BMs.</P>
Region-specific plasticity in the epileptic rat brain: A hippocampal and extrahippocampal analysis
Jung, Keun-Hwa,Chu, Kon,Lee, Soon-Tae,Kim, Jin-Hee,Kang, Kyung-Muk,Song, Eun-Cheol,Kim, Se-Jeong,Park, Hee-Kwon,Kim, Manho,Lee, Sang Kun,Roh, Jae-Kyu Blackwell Publishing Ltd 2009 Epilepsia Vol.50 No.3
<P>Summary</P><P><U>Purpose:</U> </P><P>Recent evidence suggests that aberrant neuro/gliogenesis and/or inflammation play critical roles in epileptogenesis. Although the plastic and inflammatory changes have been described in the postseizure hippocampus, little data is available concerning extrahippocampal regions, notably in the piriform and entorhinal cortices, amygdala, and parts of the thalamus. In this study, we examined histological changes in whole epileptic rat brain, with respect to cell death, cell genesis, and inflammation.</P><P><U>Methods and Results:</U> </P><P>Experimental status epilepticus (SE) was induced using a lithium-pilocarpine injection. Neuronal death was evident in the amygdala, piriform, and entorhinal cortices, as well as the subfields of hippocampus. Microglial activation was observed in more extended limbic areas, such as, the hippocampus, entorhinal, perirhinal and piriform cortices, amygdala, thalamus, and hypothalamus, and a robust increase of cell genesis was noted in these damaged areas. The majority of newly generated cells in extrahippocampal areas proliferated in situ, and differentiated mainly into astrocytes or oligodendrocytes. In addition, stromal cell-derived factor-1α was found to be induced in close temporal and anatomical association with seizure-induced plasticity.</P><P><U>Discussion:</U> </P><P>These findings indicate that neuronal death, inflammation, and cell genesis are substantially associated throughout the entire brain and that they may influence the epileptogenic process and clinical manifestations.</P>
PAUT-based defect detection method for submarine pressure hulls
Jung, Min-jae,Park, Byeong-cheol,Bae, Jeong-hoon,Shin, Sung-chul The Society of Naval Architects of Korea 2018 International Journal of Naval Architecture and Oc Vol.10 No.2
A submarine has a pressure hull that can withstand high hydraulic pressure and therefore, requires the use of highly advanced shipbuilding technology. When producing a pressure hull, periodic inspection, repair, and maintenance are conducted to maintain its soundness. Of the maintenance methods, Non-Destructive Testing (NDT) is the most effective, because it does not damage the target but sustains its original form and function while inspecting internal and external defects. The NDT process to detect defects in the welded parts of the submarine is applied through Magnetic particle Testing (MT) to detect surface defects and Ultrasonic Testing (UT) and Radiography Testing (RT) to detect internal defects. In comparison with RT, UT encounters difficulties in distinguishing the types of defects, can yield different results depending on the skills of the inspector, and stores no inspection record. At the same time, the use of RT gives rise to issues related to worker safety due to radiation exposure. RT is also difficult to apply from the perspectives of the manufacturing of the submarine and economic feasibility. Therefore, in this study, the Phased Array Ultrasonic Testing (PAUT) method was applied to propose an inspection method that can address the above disadvantages by designing a probe to enhance the precision of detection of hull defects and the reliability of calculations of defect size.
Energetics for Interfaces between Group IV Transition Metal Carbides and bcc Iron
Jung, Woo-Sang,Lee, Seung-Cheol,Chung, Soon-Hyo The Iron and Steel Institute of Japan 2008 ISIJ international Vol.48 No.9
<P>An <I>ab initio</I> study was carried out on interfacial energies and misfit strain energies at coherent interfaces between Fe(bcc structure) and MCs(NaCl structure, M=Ti, Zr, Hf). The interfacial energies at relaxed interfaces, Fe/TiC, Fe/ZrC and Fe/HfC, were 0.263, 0.153 and 0.271 J/m<SUP>2</SUP>, respectively. The influence of bond energy was estimated using the discrete lattice plane/nearest neighbor broken bond model. It was found that the dependence of interfacial energy on the type of carbide was closely related to changes of the bond energies between Fe, M and C atoms before and after formation of the interfaces Fe/MC. The misfit strain energies in Fe/TiC, Fe/ZrC and Fe/HfC systems were 0.390, 1.692 and 1.408 eV per 16 atoms (Fe; 8 atoms and MC; 8 atoms). The misfit strain energy became larger when the difference in lattice parameters between the bulk Fe and the bulk MCs increased.</P>
Entering and Exiting Routes of Hynobius leechii to a Breeding Site and Staying Time within the Site
Sung, Ha-Cheol,Lee, Jung-Hyun,Park, Dae-Sik The Ecological Society of Korea 2005 Journal of Ecology and Environment Vol.28 No.5
To study entering and exiting routes of male and female Hynobius leechii to a breeding site and staying time of them within the breeding site, we monitored a breeding population located in the research forests of Kangwon National University. The breeding site was surrounded by a drift fence associated with nine pitfall traps. The breeding season of this population was about one month, from 16 March to 13 April, 2005. Breeding males arrived earlier at the breeding pond than females did. The operational sex ratio (OSR), defined as the ratio of males to females which are ready to mate, over a breeding season was female-biased as 0.67 male vs 1 female (57 males vs 87 females), but daily OSRs, OSR in a particular day, within the breeding pond were male-biased with $1.36\sim7.5$ male vs f female in six days out of seven investigated days. While breeding males stayed in the breeding pond for about 11 days, breeding females left the pond as soon as they completed oviposition. However, the females stayed at terrestrial areas near the pond for about seven days before completely leaving the breeding site. Entering and exiting routes to the breeding site were different between males and females, and between ovulated and oviposited females. Both males and females arrived earlier at the breeding site stayed longer within the site. Males stayed longer within the breeding site lost more body weight.