J.D. Kim

Dong-Pusan College, Tsau-liang-hai, Busan, South Korea

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Publications (21)45.66 Total impact

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    ABSTRACT: We have been able to gain insights into ferroelectric thin films from measurements of the thickness-dependence of various characteristics of these films, such as coercive field (Ec), remnant polarization (Pr) and leakage current. Fully-strained SrRuO3 (SRO)/BaTiO3 (BTO)/SRO hetero-structures with ultra-thin BTO layers from 30 nm to 5 nm were deposited on SrTiO3 (001) substrates by pulsed laser deposition. Well-defined interfaces between the ferroelectric BTO layer and the electrode SRO layer were confirmed by a tunneling electron microscope image and by the thickness-independence of their coercive fields. The ferroelectric hysteresis loop was observed in the thinnest BTO layer (5 nm thickness). The decrease of ferroelectric polarization was observed as the BTO thickness decreased reduced, which agreed well with the theoretical prediction. Resistive switching behavior was not observed in the thinnest films, but was observed in thicker films after dielectric breakdown.
    No preview · Article · Aug 2005 · Thin Solid Films
  • H. S. Lee · J. I. Yoon · J. D. Kim · Pradeep Bansal
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    ABSTRACT: Experimental results of heat transfer characteristic and pressure gradients of hydrocarbon refrigerants R-290, R-600a, R-1270 and HCFC refrigerant R-22 during evaporating inside horizontal double pipe heat exchangers are presented. The test sections have one tube diameter of 12.70mm with 0.86mm wall thickness, another tube diameter of 9.52mm with 0.76mm wall thickness was used for this study. The local evaporating heat transfer coefficients of hydrocarbon refrigerants were higher than those of R-22. The average evaporating heat transfer coefficient increased as the mass flux increased. It is showed the higher values in hydrocarbon refrigerants than R-22. Comparing the heat transfer coefficient of experimental results with that of other correlations, the obtained results from the experiments had coincided with most of the Kandlikar’s correlation. Hydrocarbon refrigerants have higher pressure drop than R-22 in 12.7mm and 9.52mm. This results form the study can be used in the case of designing heat transfer exchangers using hydrocarbons as the refrigerant for the air-conditioning systems.
    No preview · Article · Jun 2005 · International Journal of Heat and Mass Transfer
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    ABSTRACT: To investigate the critical thickness of ferroelectric BaTiO3 (BTO) films, we fabricated fully strained SrRuO3/BTO/SrRuO3 heterostructures on SrTiO3 substrates by pulsed laser deposition with in situ reflection high-energy electron diffraction. We varied the BTO layer thickness from 3 to 30 nm. By fabricating 10×10 mum2 capacitors, we could observe polarization versus electric-field hysteresis loops, which demonstrate the existence of ferroelectricity in BTO layers thicker than 5 nm. This observation provides an experimental upper bound of 5 nm for the critical thickness. The BTO thickness-dependent scaling of the remanent polarization agrees with the predictions of recent first-principle simulations [J. Junquera and P. Ghosez, Nature 422, 506 (2003)].
    Full-text · Article · Mar 2005 · Applied Physics Letters
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    ABSTRACT: 7A high quality epitaxial SrRuO 3(SRO)/BaTiO 3(BTO)/SRO/SrTiO 3 (001) heterostructure was grown by pulsed laser deposition with in situ reflection high-energy electron diffraction. The growth mode and crystallinity of the heterostructure were verified by X-ray diffraction and atomic force microscopy. Ferroelectric (FE) hysteresis loops could be observed down to 9 nm of BTO thickness. Remanent polarization decreased as the FE layer thickness decreased. In addition, all the capacitors showed imprint phenomena. The strength of the imprint increased as the BTO layer thickness decreased. Possible origins of the thickness-dependent imprint and the polarization reduction are discussed.
    No preview · Article · Jan 2005 · Journal- Korean Physical Society
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    ABSTRACT: Calbindin D-28k (CB), a calcium-binding protein, containing neurons in the hippocampus plays an important role in hippocampal excitability in epilepsy. In the present study, we investigated changes of CB immunoreactivity after adrenalectomy (ADX) in the hippocampus and dentate gyrus of the seizure sensitive gerbil, which is susceptible to seizure to identify roles of CB in epileptogenesis. The changes of the CB immunoreactivity after ADX were significant in the hippocampal CA1 region. By 24 h after ADX, CB-immunoreactive CA1 pyramidal cells and CB immunoreactivity increased. At this time, well-stained dendrites projected to the stratum radiatum. Thereafter, the CB immunoreactivity decreased time dependently by 96 h after ADX. In the dentate gyrus, the changes of CB-immunoreactive neurons were mainly observed in the granule cell layer. The number and immunoreactivity of CB-immunoreactive neurons was high at 24 h after ADX, thereafter, those decreased by 96 h after ADX. These results suggest that glucocorticoid has an important role in modulating the seizure activity and CB serves an inhibitory function, which regulates the seizure activity and output signals from the hippocampus.
    No preview · Article · Nov 2004 · Anantomia Histologia Embryologia
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    ABSTRACT: To determine incidence of invasive Haemophilus influenzae type b (Hib) disease in a defined population of Jeonbuk Province, Korea, children <5 years were evaluated in prospective, population-based surveillance of invasive bacterial diseases using standardized methods for patient referral, clinical evaluation and laboratory testing (optimized culture, latex agglutination, polymerase chain reaction). Vaccine utilization was assessed with vaccination histories of patients in surveillance, monthly data on Hib vaccine distribution and a coverage survey of clinic patients in study population. From September 1999 to December 2001, 2176 children were evaluated for possible meningitis, 1541 had no cerebrospinal fluid (CSF) findings of meningitis, 605 had CSF abnormalities (suspected bacterial meningitis) but no pathogen identified; six patients had probable Hib meningitis and eight had confirmed Hib meningitis. The annual suspected bacterial meningitis incidence was 258.4/100,000 <5 years and the probable/confirmed Hib meningitis incidence was 6.0/100,000 <5 years. Pneumococcal meningitis incidence was 2.1/100,000 <5 years and Group B streptococcal meningitis incidence was 0.17/1000 live births. A total of 69,589 Hib vaccine doses were distributed during the study. Hib vaccine coverage was negligible initially but increased to 16% (complete Hib immunization) and 27% (partial immunization) in final months of study. Suspected bacterial meningitis incidence was high but proven invasive Hib meningitis incidence was low. Hib was leading cause of bacterial meningitis yet bacterial pathogens were identified in only 4% of abnormal CSF. These findings may reflect truly low incidence, presumptive antibiotic treatment, partial Hib immunization, or incomplete clinical evaluations. Given the apparent Hib meningitis burden in Jeonbuk Province, additional studies to describe other invasive Hib syndromes, Hib-associated mortality and disability, and economic impact of Hib disease will be useful to guide public health decisions regarding routine Hib vaccine introduction.
    Full-text · Article · Sep 2004 · Vaccine
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    ABSTRACT: Ginsenosides from Panax ginseng are metabolized by human intestinal bacteria after oral administration of ginseng extract. 20(S)-Protopanaxatriol (PPT) is one of the major metabolites of ginsenosides. Inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) are important enzymes that mediate inflammatory processes. Improper up-regulation of iNOS and/or COX-2 has been associated with the pathogenesis of inflammatory diseases and certain types of human cancers. Here, we investigated whether PPT could modulate iNOS and COX-2 expressions in RAW 264.7 macrophages stimulated with the endotoxin lipopolysaccharide (LPS). We found that PPT blocked the increase in LPS-induced iNOS and COX-2 expressions through inactivation of nuclear factor-kappaB by preventing I-kappaBalpha phosphorylation and degradation. Thus, it may be possible to develop PPT as a useful agent for chemoprevention of cancer or inflammatory diseases.
    No preview · Article · Apr 2004 · Cancer Letters
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    ABSTRACT: We investigated the effects of the gallotannin penta-O-galloyl-β-d-glucose (PGG) on interleukin (IL)-8 gene expression and nuclear factor (NF)-κB activation. PGG inhibited IL-8 production and gene expression in human monocytic U937 cells stimulated with phorbol myristate acetate (PMA), as measured by enzyme-linked immunosorbent assay and reverse transcription-polymerase chain reaction analysis, respectively. PGG also inhibited PMA-mediated NF-κB activation, as measured by electromobility shift assay. Furthermore, PGG prevented PMA-mediated degradation of the NF-κB inhibitory protein I-κBα, as measured by Western blot analysis. PGG also inhibited both IL-8 production and NF-κB activation in the U937 cells stimulated with tumor necrosis factor-α. These results suggest that PGG, a major constituent of the root cortex of Paeonia suffruticosa ANDREWS, can inhibit IL-8 gene expression by a mechanism involving its inhibition of NF-κB activation, which is dependent on I-κBα degradation.
    No preview · Article · Apr 2004 · International Immunopharmacology
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    H.J. Lee · S.C. Lee · J.D. Kim · Y.G. Oh · B.K. Kim · C.W. Kim · K.J. Kim
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    ABSTRACT: This study was conducted to investigate in vitro methane production of feed ingredients and relationship between the content of crude nutrients and methane production. Feed ingredients (total 26) were grouped as grains (5 ingredients), brans and hulls (8), oil seed meals (9) roughages (3), and animal by-product (1) from their nutrient composition and their methane production protential were measured by in vitro gas test. Among the groups, the in vitro methane productions for both 6 and 24 h incubation were highest in grains, followed by brans and hulls, oil meals and roughages, animal byproducts. Within the group of grains, methane production from wheat flour was the highest, followed by wheat, corn, tapioca, and then oat. Within the brans and hulls, soybean hull showed the highest methane production and cotton seed hull, the lowest. Methane production from oil meals was lower compared with grains and brans and hulls, and in decreasing order production from canola meal was followed by soybean meal, coconut meal, and corn germ meal (p
    Preview · Article · Aug 2003 · Asian Australasian Journal of Animal Sciences
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    ABSTRACT: Charge retention loss was investigated for Pt/Pb(Zr-0.4 Ti-0.6 )O-3 /Pt capacitors in short- ( t < 1 s) and long-time ( t > 1 s) regimes. The short-time retention loss behaviors of fatigued capacitors were well described by a power-law function and analyzed in terms of a superposition of polarization relaxation with a distribution of relaxation time. We showed that depolarization field governs the retention loss in the short-time regime. Fatigue-induced defects, probably the interfacial passive layers, seemed to increase the depolarization field. In the long-time regime, the retention loss is shown to be related to the internal field developed parallel to the polarization direction. Particularly in "opposite-state" retention, the internal field caused polarization backswitching resulting in a severe degradation of retention characteristics. The internal field developed during retention was estimated by using Merz equations of polarization switching. Defects dynamics under electric field was discussed in conjunction with the recovery process of imprint.
    No preview · Article · Jun 2003 · Integrated Ferroelectrics
  • T.W. Noh · S. Seo · B.S. Kang · J.D. Kim · J.-G. Yoon · Y.K. Lee · Y.S. Park
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    ABSTRACT: If ferroelectric random access memory is to become one of major non-volatile memories, the problems in conjunction with existing CMOS integration should be resolved. One of the problems is hydrogen-induced degradation, which occurs during the dielectric layer deposition or the forming gas annealing. We investigated the degradation mechanisms in widely used materials, such as SrBi2Ta2O9, Pb(Zr,Ti)O3 (PZT), and newly discovered (Bi,La)4Ti3O12 (BLT) films. We found that these materials have different hydrogen-induced degradation mechanisms: The degradation of the Bi-layered BLT and SET should be due to the chemical decomposition of weak Bi-O bond, but that of PZT is most likely come from trapped defects charges.
    No preview · Article · Apr 2003 · Journal- Korean Physical Society
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    ABSTRACT: Charge retention loss was investigated for Pt/Pb(Zr0.4Ti0.6)O3/Pt capacitors in short- (t < 1 s) and long-time (t > 1 s) regimes. The short-time retention loss behaviors of fatigued capacitors were well described by a power-law function and analyzed in terms of a superposition of polarization relaxation with a distribution of relaxation time. We showed that depolarization field governs the retention loss in the short-time regime. Fatigue-induced defects, probably the interfacial passive layers, seemed to increase the depolarization field. In the long-time regime, the retention loss is shown to be related to the internal field developed parallel to the polarization direction. Particularly in “opposite-state” retention, the internal field caused polarization backswitching resulting in a severe degradation of retention characteristics. The internal field developed during retention was estimated by using Merz equations of polarization switching. Defects dynamics under electric field was discussed in conjunction with the recovery process of imprint.
    Full-text · Article · Mar 2003 · Integrated Ferroelectrics
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    ABSTRACT: Effects of forming gas annealing (FGA) were investigated on ferroelectric Bi3.25La0.75Ti3O12 (BLT) thin films fabricated by a chemical solution deposition. With the FGA up to 350 °C, the Pt/BLT/Pt capacitors showed good ferroelectric characteristics without significant degradation. As the FGA temperature was increased, a decomposition of the BLT powder sample was observed by using thermogravimetric analysis. By comparing the time-dependent weight loss of BLT with that of Bi4Ti3O12 during FGA, La doping was found to significantly impede the decomposition rate. The decomposition, especially in the (Bi2O2)2+ layers, was discussed as a hydrogen-induced degradation mechanism in the Bi-layered perovskite ferroelectrics. © 2002 American Institute of Physics.
    No preview · Article · Sep 2002 · Applied Physics Letters
  • I.S Choi · J.D Kim · E Kim · J.I Yoon
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    ABSTRACT: This paper is concerned with the development of a new method for making and separating ice and saving floated ice by installing an evaporation plate at underwater within a storage tank. In a conventional harvest-type ice storage system, a tank saves ice by separating a formed ice from an installed evaporation plate, which is located above an ice storage tank as an ice storage system. A new harvest-type method shows better heat transfer efficiency than a convectional method. It is because the evaporation panel is directly contacted with water in a storage tank. Also, at a conventional system a circulating pump, a circulating water distributor and a piping are installed, but these components are not necessary in a new method. In this study two kinds of ice storage systems are experimentally investigated to study the thermal characteristics of ice storage tanks. The results show the applicable possibility and performance enhancement of a new type.
    No preview · Article · Mar 2002 · International Journal of Heat and Mass Transfer
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    ABSTRACT: A large amount of nitric oxide (NO) production following the induction of inducible NO synthase (iNOS) gene has been implicated in the pathogenesis of inflammatory diseases. A phenolic compound, bakuchiol, isolated from Psoralea corylifolia L. (Leguminosae) inhibited NO production in RAW 264.7 macrophages activated with interferon-γ and lipopolysaccharide. The mechanistic studies showed that bakuchiol inhibited the expression of iNOS mRNA through the inactivation of nuclear transcription factor-κB. Thus, bakuchiol may be a useful candidate for the development of a drug to treat inflammatory diseases related to iNOS gene over-expression.
    No preview · Article · Oct 2001 · International Immunopharmacology
  • J C Yoo · H O Pae · B M Choi · W I Kim · J D Kim · Y.M. Kim · H T Chung
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    ABSTRACT: The effects of ionizing irradiation on the nitric oxide (NO) production in murine embryonic liver cell line, BNL CL.2 cells, were investigated. Various doses (5-40 Gy) of radiation made BNL CL.2 cells responsive to interferon-gamma alone for the production of NO in a dose-dependent manner. Small amounts of lipopolysaccharide (LPS) or tumor necrosis factor-alpha (TNF-alpha) synergized with IFN-gamma in the production of NO from irradiated BNL CL.2 cells, even though LPS or TNF-alpha alone did not induce NO production from the same cells. Immunoblots showed parallel induction of inducible nitric oxide synthase (iNOS). NO production in irradiated BNL CL.2 cells by IFN-gamma or IFN-gamma plus LPS was decreased by the addition of catalase, suggesting that H(2)O(2) produced by ionizing irradiation primed the cells to trigger NO production in response to IFN-gamma or IFN-gamma plus LPS. Furthermore, the treatment of nongamma-irradiated BNL CL.2 cells with H(2)O(2) made the cells responsive to IFN-gamma or IFN-gamma plus LPS for the production of NO. This study shows that ionizing irradiation has the ability to induce iNOS gene expression in responsive to IFN-gamma via the formation of H(2)O(2) in BNL CL.2 murine embryonic liver cells.
    No preview · Article · Mar 2000 · Free Radical Biology and Medicine
  • H O Pae · J C Yoo · B M Choi · C L Kang · J D Kim · H T Chung
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    ABSTRACT: Taxol, an antineoplastic drug, increases the fraction of cells in G2/M phases of cell cycle, induces apoptosis of leukemic cells, and activates macrophages to produce nitric oxide (NO) in response to interferon-gamma. NO has been found to play roles as pro-apoptotic or anti-apoptotic effector molecules. In this study, we investigate effects of NO on taxol-induced apoptosis in human myeloid leukemia cell, HL-60. Incubation of the cells with taxol for 24 hr induced marked DNA fragmentation of HL-60 cells. Treatment of the cells with S-nitrosogluthathione (GSNO), a NO-generating agent, protected the cells against taxol-induced apoptosis. Cell cycle analysis showed that treatment of the cells with 100 nM taxol for 12 hr rendered the cells to be accumulated in G2/M phase, but the cotreatment of the cells with taxol and 0.1 mM GSNO decreased the accumulation of the cell in G2/M phases, suggesting that NO might interfere entering of taxol-treated cells into G2/M phases. Deferoxamine or mimosine, which can arrest cells mainly at G1/S phases, also decreased taxol-induced apoptosis and reduced the number of the taxol-treated cells arresting in G2/M phases. Thus, we conclude that a protective effect of NO on taxol-treated cells from apoptosis may be partially caused by interfering entering of the taxol-treated cells into G2/M phases.
    No preview · Article · Dec 1999 · Immunopharmacology and Immunotoxicology
  • M S Lee · C W Kang · H Ryu · J D Kim · H T Chung
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    ABSTRACT: We observed the response of plasma growth hormone (GH), insulin-like growth factor-I (IGF-I) and testosterone (T) to an acute period of ChunDoSunBup (CDSB) Qi-training. Although the basal level of GH was not different between the two groups, after the portion of the training in which the subjects were physically active (the mid-training point), plasma GH levels increased by 7.26 fold (p < 0.05) in the elderly trainees and by 1.66 fold (p < 0.05) in the young. In response to CDSB Qi-training, IGF-I levels in the young increased significantly at mid-training point, but there were no increase in the elderly. Significant correlations existed between GH and IGF-I levels in the young subjects, but not in the elderly. The T level at the mid-training point increased significantly in elderly subjects but not in the young. These results suggest that CDSB Qi-training is a potential method for modulating of the secretion of growth factor in the young and the elderly, but that the elderly IGF-I response does not equal that of the young. In addition, our study suggests CDSB Qi-training may be one mode of therapy applicable to growth factor related disorders such as GH deficiency in children and osteoporosis in the elderly, especially women.
    No preview · Article · Jan 1999 · The American Journal of Chinese Medicine
  • Hoon Ryu · S M Jeong · C D Jun · J H Lee · J D Kim · B S Lee · H T Chung
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    ABSTRACT: Growth hormone (GH) primes and augments O2- production in neutrophils. The exact signaling of the priming pathway by GH has not been demonstrated. In this study, we investigated intracellular signaling of priming by recombinant human growth hormone (rGH) in human neutrophils. A low concentration of rGH (10-100 ng/ml) significantly enhanced the O2- production from neutrophils triggered with N-formyl-1-methionyl-1-leucyl-1-phenylalanine in a dose-dependent manner. Recombinant GH directly increased the fluorescence intensity of intracellular Ca2+ labeled with fluo 3-AM in neutrophils. The change of fluorescence intensity of cytosolic Ca2+ was dependent on the rGH concentration. The peak level of fluorescence intensity was observed at 3 to 5 min after treatment with rGH. The priming effect of rGH on O2- production via Ca2+ was abrogated by Ca2+ channel blockers such as dentrolene and verapamil. Furthermore, preincubation with genistein, a tyrosine kinase inhibitor, blocked the rGH-induced increases in Ca2+ and O2- production. This finding suggests that GH can act through the increase of intracellular Ca2+ as a priming agent to activate neutrophils for an enhanced respiratory burst.
    No preview · Article · Apr 1997 · Brain Behavior and Immunity
  • M.K. Lee · H.S. Lee · G.P. Choi · D.H. Oh · J.D. Kim · C.Y. Yu · H.Y. Lee

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Publication Stats

449 Citations
45.66 Total Impact Points

Institutions

  • 2002-2005
    • Dong-Pusan College
      Tsau-liang-hai, Busan, South Korea
    • Seoul National University
      • Department of Physics and Astronomy
      Sŏul, Seoul, South Korea
  • 2004
    • Hallym University
      • College of Medicine
      Sŏul, Seoul, South Korea
  • 1999-2004
    • Wonkwang University School of Medicine and Hospital
      Riri, North Jeolla, South Korea
    • Chonbuk National University
      • College of Veterinary Medicine
      Tsiuentcheou, Jeollabuk-do, South Korea
  • 1997-2004
    • Wonkwang University
      • • College of Oriental Medicine
      • • Department of Medicine
      Riri, North Jeolla, South Korea
  • 2000
    • Kangwon National University
      • Department of Molecular and Cellular Biochemistry
      Gangneung, Gangwon, South Korea