Radiologic Management of Complications after Gastrectomy

Hyoung Ook Kim 대한외과학회 2019 대한외과학회 학술대회 초록집 Vol.2019 No.10

Investigation on the Spot for Grounding Systems in Buildings

Hyoung-Jun Gil,Dong-Woo Kim,Dong-Ook Kim,Hyang-Kon Kim 한국조명·전기설비학회 2010 조명·전기설비학회논문지 Vol.24 No.3

This paper deals with investigation on the spot for grounding systems of buildings based on international standards at construction sites. The investigation was carried out for grounding method, grounding type, shape of grounding electrode, grounding for a lightning protection system, continuity of steelwork in reinforced concrete structures, etc. The investigation on the spot was performed by a researcher and engineer with over fifteen years of industry experience all over the country. As a result of the investigation on the spot in 13 buildings, common grounding and structure grounding methods were dominant. The safety improvement methods include installation of equipotential bonding conductors for the connection to the main earthing terminal, equipotential bonding conductors for supplementary bonding, use of Surge Protective Devices (SPD), and safe connections between earthing conductors and the rebar.

NecroX as a Novel Class of Mitochondrial Reactive Oxygen Species and ONOO− Scavenger

Hyoung Jin Kim,Sun Young Koo,Bong-Hyun Ahn,Oeuk Park,Doo Hoe Park,Dong Ook Seo,Jong Heon Won,Hyeon Joo Yim,Hyo-Shin Kwak,Heui Sul Park,정철웅,Young Leem Oh,Soon Ha Kim 대한약학회 2010 Archives of Pharmacal Research Vol.33 No.11

Mitochondrial reactive oxygen species and reactive nitrogen species are proven to be major sources of oxidative stress in the cell; they play a prominent role in a wide range of human disorders resulting from nonapoptotic cell death. The aim of this study is to examine the cytoprotective effect of the NecroX series against harmful stresses, including pro-oxidant (tertiarybutylhydroperoxide), doxorubicin, CCl4, and hypoxic injury. In this study, these novel chemical molecules inhibited caspase-independent cell death with necrotic morphology, which is distinctly different from apoptosis, autophagy, and necroptosis. In addition, they displayed strong mitochondrial reactive oxygen species and ONOO− scavenging activity. Further, oral administration of these molecules in C57BL/6 mice attenuated streptozotocin-induced pancreatic islet β-cell destruction as well as CCl4-induced hepatotoxicity in vivo. Taken together, these results demonstrate that the NecroX series are involved in the blockade of nonapoptotic cell death against mitochondrial oxidative stresses. Thus, these chemical molecules are potential therapeutic agents in mitochondria-related human diseases involving necrotic tissue injury.

Effects of Position of Auxiliary Probe on Ground Resistance Measurement Using Fall-of-Potential Method

Hyoung Jun Gil,Dong Woo Kim,Dong Ook Kim,Ki Yeon Lee,Hyang Kon Kim 한국안전학회(구-한국산업안전학회) 2008 International Journal of Safety Vol.7 No.2

In this paper, the effects of the position and the angle of the potential probes on the measurements of the ground resistance using the fall-of-potential method are described and the testing techniques for minimizing the measuring errors are proposed. The fall-of-potential method is theoretically based on the potential and current measuring principle and the measuring error is primarily caused by the position and angle of auxiliary probes. In order to analyze the relative error in the measured value of the ground resistance due to the position of the potential probe, the ground resistance was measured for the case in which the distance of the current probe was fixed at 50[m] and the distance of the potential probe was located from l0[m] to 50[m). Also, the potential probe was located in turn at 30[˚], 45[˚], 60[˚], 90[˚], and 180[˚]. As a consequence, relative error decreased with increasing distance of the potential probe and decreasing angle between the current probe and potential probe. The results could help to determine the position of the potential probe during the ground resistance measurement.

Analysis of Risk Voltage for Grounding Electrode by Injection of Earth Leakage Current

( Hyoung Jun Gil ),( Dong Woo Kim ),( Dong Ook Kim ),( Ki Yeon Lee ),( Hyun Wook Moon ),( Hyang Kon Kim ),( Gyung Suk Kil ) 한국안전학회(구-한국산업안전학회) 2009 International Journal of Safety Vol.8 No.2

Endovascular Aneurysm Repair for Abdominal Aortic Aneurysm: A Comprehensive Review

Hyoung Ook Kim,Nam Yeol Yim,Jae Kyu Kim,Yang Jun Kang,Byung Chan Lee 대한영상의학회 2019 Korean Journal of Radiology Vol.20 No.8

Abdominal aortic aneurysm (AAA) can be defined as an abnormal, progressive dilatation of the abdominal aorta, carrying a substantial risk for fatal aneurysmal rupture. Endovascular aneurysmal repair (EVAR) for AAA is a minimally invasive endovascular procedure that involves the placement of a bifurcated or tubular stent-graft over the AAA to exclude the aneurysm from arterial circulation. In contrast to open surgical repair, EVAR only requires a stab incision, shorter procedure time, and early recovery. Although EVAR seems to be an attractive solution with many advantages for AAA repair, there are detailed requirements and many important aspects should be understood before the procedure. In this comprehensive review, fundamental information regarding AAA and EVAR is presented.

Blue Phosphorescence with High Quantum Efficiency Engaging the Trifluoromethylsulfonyl Group to Iridium Phenylpyridine Complexes

Kim, Jin-Hyoung,Kim, So-Yoen,Jang, Seol,Yi, Seungjun,Cho, Dae Won,Son, Ho-Jin,Kang, Sang Ook American Chemical Society 2019 Inorganic Chemistry Vol.58 No.23

<P>Incorporation of an electron-withdrawing −SO<SUB>2</SUB>CF<SUB>3</SUB> substituent to cyclometalating C^N-phenylpyridine (ppy) ligand resulted in an expected blue-shifted phosphorescence in the corresponding homoleptic <B>Ir(ppySCF</B><SUB><B>3</B></SUB><B>)</B><SUB><B>3</B></SUB> complex, showing the emission of λ<SUB>em</SUB> = 464 nm at 300 K. One of its heteroleptic derivatives, modified by a pyrazolyl borate LX ligand, <B>Ir(ppySCF</B><SUB><B>3</B></SUB><B>)</B><SUB><B>2</B></SUB><B>(bor)</B>, exhibited further blue-shifted phosphorescence of λ<SUB>em</SUB> = 460 nm at 300 K. Cyclic voltammograms (CVs) and density-functional theory (DFT) calculations supported the efficacy of the electron-withdrawing capability of the SO<SUB>2</SUB>CF<SUB>3</SUB> substituent lowering HOMO energy and obtained widened bandgaps and resumed blue emissions for all of the iridium complexes studied. The homoleptic complexes of both substituents, <B>Ir(ppySCF</B><SUB><B>3</B></SUB><B>)</B><SUB><B>3</B></SUB> and <B>Ir(ppySF)</B><SUB><B>3</B></SUB>, reached the higher quantum yields (<I>Φ</I><SUB>PL</SUB>) of (0.89 and 0.72), respectively. Similarly, emission quantum yields (<I>Φ</I><SUB>PL</SUB>) of the heteroleptic derivatives were reported to be (0.75, 0.83, and 0.87) for <B>Ir(ppySCF</B><SUB><B>3</B></SUB><B>)</B><SUB><B>2</B></SUB><B>(acac)</B>, <B>Ir(ppySCF</B><SUB><B>3</B></SUB><B>)</B><SUB><B>2</B></SUB><B>(bor)</B>, and <B>Ir(ppySCF</B><SUB><B>3</B></SUB><B>)</B><SUB><B>2</B></SUB><B>(pic)</B>, respectively. Emission kinetics support the enhanced quantum efficiency when <I>k</I><SUB>r</SUB> and <I>k</I><SUB>nr</SUB> values are compared between <B>Ir(ppySCF</B><SUB><B>3</B></SUB><B>)</B><SUB><B>3</B></SUB> and <B>Ir(ppySF)</B><SUB><B>3</B></SUB>, and both values favorably contribute to attaining a higher quantum efficiency for <B>Ir(ppySCF</B><SUB><B>3</B></SUB><B>)</B><SUB><B>3</B></SUB>. Among solution-processed multilayered devices having an ITO/PEDOT:PSS/TCTA:Ir dopant (10:1, <I>w</I>/<I>w</I>)/TmPyPB/Liq/Al structure, a heteroleptic dopant, <B>Ir(ppySCF</B><SUB><B>3</B></SUB><B>)</B><SUB><B>2</B></SUB><B>(bor)</B>, exhibited better device performance, reporting an external quantum efficiency (EQE) of 1.14%, current efficiency (CE) of 2.31 cd A<SUP>-1</SUP>, and power efficiency (PE) of 1.21 lm W<SUP>-1</SUP>, together with blue chromaticity of CIE<SUB>x,y</SUB> = (0.16, 0.32).</P><P>Blue phosphorescence of Ir(III) complexes can be tuned with the introducing of strong electron withdrawing substituents and the variation in the ancillary ligands.</P> [FIG OMISSION]</BR>

Triplet Energy Transfer between a Sacrificial PMP and Blue TPF2 Iridium Dopants Leading to Enhancement of OLED Device Performance

Kim, So-Yoen,Kim, Jin-Hyoung,Son, Mi Rang,Yi, Seungjun,Kim, Chul Hoon,Son, Ho-Jin,Kang, Sang Ook American Chemical Society 2019 JOURNAL OF PHYSICAL CHEMISTRY C - Vol.123 No.31

<P>In this study, we prepared phenylimidazole-based C^N-cyclometalated Ir(III) complexes (<B>DMP</B>, <B>TPF2</B>) and a C^C-cyclometalated Ir(III) complex (<B>PMP</B>), and investigated the energy transfer process by examining the intermolecular interactions between the two cyclometalated Ir(III) complexes. In films doped with 3% Ir(C^C)<SUB>3</SUB> complex (<B>PMP</B>) and 15% Ir(C^N)<SUB>3</SUB> complex (<B>DMP</B> or <B>TPF2</B>), the <B>PMP</B> effectively induced energy transfer to the <B>DMP</B> or <B>TPF2</B>. This intermolecular energy transfer process was investigated using a picosecond time-resolved emission spectroscopic method. In the case of mixing <B>PMP</B> with <B>DMP</B>, where two types of luminescence were observed at 470 and 580 nm, the emission at 470 nm was due to <B>DMP</B>, while the emission at 580 nm can be assigned as the intermolecular exciplex emission. By contrast, in the case of mixing <B>PMP</B> with <B>TPF2</B>, the emission at 465 nm corresponding to the <B>PMP</B> emission region decreased for 18.5 ns, while the emission at 530 nm corresponding to <B>TPF2</B> increased. This emission can be attributed to the energy transfer from <B>PMP</B> to <B>TPF2</B>. In addition, no change was observed in the longer wavelength region than the <B>TPF2</B> emission region for 10 μs. We analyzed the energy transfer process when <B>PMP</B> was added to the dopant (<B>DMP</B> and <B>TPF2</B>) and found that <B>TPF2</B> was more efficient than <B>DMP</B> in the device without <B>PMP</B> doping, but it showed performance deterioration in high current density (>1 mA/cm<SUP>2</SUP>) owing to activation of fluorinated ligands. Finally, it was confirmed that the operation lifetime and efficiency of the device were improved by doping 3% of <B>PMP</B> in emissive layer (EML).</P> [FIG OMISSION]</BR>

Influence of bulky substituents on the photophysical properties of homoleptic iridium(iii) complexes

Kim, Jin-Hyoung,Kim, So-Yoen,Cho, Dae Won,Son, Ho-Jin,Kang, Sang Ook The Royal Society of Chemistry 2019 Physical chemistry chemical physics Vol.21 No.13

<P>A new series of homoleptic cyclometalated iridium(iii) complexes based on a phenylpyridine (ppy) ligand containing bulky substituents have been synthesized and characterized. The phosphorescence behavior of the Ir complexes is investigated by steady-state and time-resolved emission spectroscopic techniques. Comparison of the results with those of the reference Ir(ppy)3 reveals that the emission color and photophysical properties of other Ir complexes are influenced by the electron-donating groups (-CH3 and phenyl derivatives) attached to the ppy ligand. In particular, systematic red-shifts are observed by increasing the electron-donating ability. The emission spectrum of Ir(Me-ppy)3, having a small electron-donating -CH3 group, is red-shifted; however, the emission quantum yield is low and the nonradiative decay constant is large. On the other hand, although bulky phenyl derivative-adducts (Ir(Ph-ppy)3, Ir(MePh-ppy)3, and Ir(diMePh-ppy)3) also exhibit red-shifted emission, their kinetic and photophysical behaviors are more optimal than those of Ir(Me-ppy)3, whose behavior does not follow the energy gap law. This deviation may be attributed to the orthogonal structure associated with the steric hindrance of bulky substituents. The molecular structure, molecular orbitals in singlet/triplet manifolds, and energy band gap are verified by density functional theory calculations.</P>

A Detailed Evaluation for the Nonradiative Processes in Highly Phosphorescent Iridium(III) Complexes

Kim, Jin-Hyoung,Kim, So-Yoen,Cho, Yang-Jin,Son, Ho-Jin,Cho, Dae Won,Kang, Sang Ook American Chemical Society 2018 JOURNAL OF PHYSICAL CHEMISTRY C - Vol.122 No.7

<P>To understand the intrinsic nature of nonradiative processes in heteroleptic cyclometalated Ir(III) complexes, highly phosphorescent Ir<SUP>3+</SUP> complexes containing 2-(3-sulfonylfluorophenyl)pyridine (ppySO<SUB>2</SUB>F) as the cyclometalated ligand were newly synthesized. Three ancillary ligands, acetylacetonate (acac), picolinate (pic), and <I>tetrakis</I>-pyrazolyl borate (bor), were employed for the preparation of the Ir(III) complexes [Ir(ppySO<SUB>2</SUB>F)<SUB>2</SUB>(acac)] (<B>Ir-acac</B>), [Ir(ppySO<SUB>2</SUB>F)<SUB>2</SUB>(pic)] (<B>Ir-pic</B>), and [Ir(ppySO<SUB>2</SUB>F)<SUB>2</SUB>(bor)] (<B>Ir-bor</B>). The molecular structures were characterized by X-ray crystallography. Blue phosphorescence maxima were observed at 458, 467, and 478 nm for <B>Ir-bor</B>, <B>Ir-pic</B>, and <B>Ir-acac</B>, respectively, at 77 K, and the corresponding emission quantum yields were determined to be 0.79, 0.80, and 0.98 in anaerobic CH<SUB>2</SUB>Cl<SUB>2</SUB> at 300 K. Additionally, the phosphorescence decay times were measured to be 3.58, 1.94, and 1.44<I>μ</I>s for <B>Ir-bor</B>, <B>Ir-pic</B>, and <B>Ir-acac</B>, respectively. No temperature dependence was observed for the emission lifetimes in 298–338 K. These results indicate that there is no activation barrier to crossing to a nonradiative state like metal-centered (MC, d–d) state. The radiative rate constants (<I>k</I><SUB>r</SUB>) are within a narrow range of 3.0–5.5 × 10<SUP>–5</SUP> s<SUP>–1</SUP>. However, the nonradiative rate constants (<I>k</I><SUB>nr</SUB>) are within a wide range of 14.2–0.52 × 10<SUP>–4</SUP> s<SUP>–1</SUP>. The <I>k</I><SUB>nr</SUB> values showed exponetial correlation with the energy gap. We carried out <I>ab</I> <I>initio</I> calculations to evaluate the energy states and their corresponding orbitals. The nonemissive MC states lie at higher energies than the emissive metal-to-ligand charge transfer (MLCT) state, and hence, the MC states can be excluded from the nonradiative pathway.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/jpccck/2018/jpccck.2018.122.issue-7/acs.jpcc.7b12449/production/images/medium/jp-2017-12449f_0009.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/jp7b12449'>ACS Electronic Supporting Info</A></P>