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Journal of Rare Earths 2015年第4期33卷 403-410页

作者： nahm.Choonwoo Semiconductor Ceramics Laboratory Department of Electrical Engineering Dongeui University

The microstructure, electrical and dielectric properties, and DC-accelerated aging of the ZPCCA （ZnO-Pr6O11-CoO- Cr203-A1203） ceramics were investigated with various contents of Er203. The ceramic phases consisted of a bulk phase of ZnO grains, and a minor secondary phase of mixture of Pr6O11 and Er203. The increase of the content of doped Er203 increased the densities of sintered pellet from 5.66 to 5.85 g/cm3, and decreased the average grain size from 9.6 to 6.3 μm. With the increase of the content of doped Er203, the breakdown field increased from 2390 to 4530 V/cm, and the nonlinear coefficient increased from 28.4 to 39.1. The sample doped with 0.25 mol.% Er203 exhibited the strongest electrical stability; variation rates for the breakdown field measured at 1.0 mA/cm2, and for the non-ohmic coefficient were -3.4% and -23,8%, respectively, after application of a stress of 0.95 Eu/125 ℃/24 h.

关键词： microstructure Er203 electrical properties aging behavior varistor ceramics rare earths

Sintering effect on ageing behavior of rare earths (Pr_6O_(11)-Er_2O_3-Y_2O_3 )-doped ZnO varistor ceramics

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Journal of Rare Earths 2012年第10期30卷 1028-1033页

作者： Choon-Woo nahm Semiconductor Ceramics Laboratory Department of Electrical Engineering Dongeui University

The electrical properties and ageing behavior of the rare earths （Pr6O11-Er2O3-Y2O3）-doped ZnO varistor ceramics were systematically investigated at sintering temperature range of 1335-1350°C. With an increase in the sintering temperature, the sintered density increased from 5.41 to 5.64g/cm3 and the average grain size increased from 5.8 to 7.9μm. The varistor properties and ageing behavior were significantly affected by small sintering temperature range of 1335-1350°C. The breakdown field noticeably decreased from 5767 to 3628V/cm with an increase in the sintering temperature. The varistor ceramics exhibited the highest nonlinear coefficient （43.2） at the sintering temperature of 1340°C. The varistor ceramics sintered at 1350°C exhibited a surprisingly excellent stability by exhibiting 0.3% in the variation rate of the breakdown field and 0.3% in the variation rate of the nonlinear coefficient for ageing stress of 0.95 E1mA/150°C/24 h.

关键词： sintering rare earths nonlinear properties ageing varistors

Nonlinear behavior of Tb_4O_7-modified ZnO-Pr_6O_(11)-based ceramics with high breakdown field

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Journal of Rare Earths 2013年第3期31卷 276-280页

作者： Choon-Woo nahm Semiconductor Ceramics Laboratory Department of Electrical EngineeringDongeui UniversityBusan 614-714Korea

The effect of Tb407 on electrical behavior of the ZnO-Pr6Oll-based varistor ceramics was investigated. Microstructural analysis indicated that the addition of Tb407 decreased average grain size from 3.6 to 3.2 and increased the sintered density from 5.58 to 5.68 g/cm3. As the amount ofTb407 increased, the breakdown field increased from 9393 to 12437 V/cm and the nonlinear coefficient increased from 50 to 65. The varistor ceramics added with 0.5 mol.% in the amount of Tb407 exhibited an excellent stability by exhibiting 0. 1% in the variation rate of the breakdown field, 0% in the variation rate of the nonlinear coefficient, and 8.8% in the variation rate of the leakage current density for DC-accelerated aging stress of 0.85 E1 mA/115 ℃/24 h.

关键词： doping ZnO breakdown field electrical properties varistor ceramics rare earths

Sintering effect on electrical properties and pulse aging behavior of(V_2O_5-Mn_3O_4-Er_2O_3 )-doped zinc oxide varistor ceramics

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Journal of Rare Earths 2014年第1期32卷 29-36页

作者： Choon-W.nahm Semiconductor Ceramics Laboratory Department of Electrical Engineering Dongeui University

The effect of sintering temperature on microstructure, electrical properties, and pulse aging behavior of （V2O5-Mn3O4-Er2O3）-doped zinc oxide varistor ceramics was systematically studied. When the sintering temperature increased, the average grain size increased from 6.1 to 8.7μm and the sintered density decreased from 5.52 to 5.43 g/cm3. The breakdown field decreased from 3856 to 922 V/cm with an increase in the sintering temperature up to 900 °C, whereas a further increase to 2352 V/cm at 925 °C. The nonlinear coefficient increased pronouncedly from 4.6 to 30.0 with an increase in the sintering temperature. The varistor ceramics sintered at 850 °C exhibited the best clamping characteristics, with the clamp voltage ratio of the range of 2.22-2.88 for pulse current of 1-25 A. The varistor ceramics sintered at 925 °C exhibited the strongest stability, with %ΔE1 mA/cm2=-8.8% after applying the multi-pulse current of 25 A.

关键词： ceramics sintering electrical properties pulse aging behavior varistors rare earths

Low-temperature crystalline lead-free piezoelectric thin films grown on 2D perovskite nanosheet for flexible electronic device applications

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Nano Research 2019年第10期12卷 2559-2567页

作者： Jong-Hyun Kim Sang Hyo Kweon Sahn nahm KU-KIST Graduate School of Converging Science and Technology Korea University145 Anam-roSeongbuk-guSeoul 02841Republic of Korea Department of Material Science and Engineering Korea University145 Anam-roSeongbuk-guSeoul 02841Republic of Korea Department of Mechanical Engineering Kobe University1-1 Rokkodai-choNadaKobe 657-8501Japan

A monolayer of Sr2Nb3Oio(SNO)is deposited on the Pt/Ti/SiCWSi(Pt?Si)or Pt/Ti/polyimide(Pt-Pl)substrate by using the Langmuir-Blodgett method and employed as a seed-layer for the growth of a crystalline(Nai_xKx)NbO3(NKN)film at 350℃.The crystalline NKN film is grown along the[001]direction on the SNO/Pt-Si(or SNO/Pt-PI)*** to the presence of oxygen vacancies in the SNO seed-layer,the NKN film exhibits low ferroelectric properties and large leakage *** ameliorate these properties,the SNO/Pt-Si substrate is annealed in a 50 Torr oxygen atmosphere at 300℃,which removes the oxygen ***,the NKN film deposited on this substrate exhibits promising electrical properties,namely a dielectric constant of 278,dissipation factor of 1.7%,a piezoelectric 8nstant of 175 pm`V^-1,and a leakage current density of 6.47 x 10^-7 A cm^-2 at-0.2 MV *** electrical properties are obtained from the NKN film grown on the flexible SNO/Pt-PI substrate at 350°***,the NKN films grown on the SNO seed-layer at 350°C can be applied to electronic devices with flexible polymer substrates.

关键词： lead-free piezoelectric thin films low-temperature-deposition process two-dimensional(2D)nanosheet seed-layers polymer substrates

Improvement in the Adhesion Between Electrode of a SOFC and Ag Paste as a Current Collector by Au Deposition

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Journal of Materials Science & Technology 2015年第3期31卷 257-263页

作者： Sang Koo Jeon Seung Hoon nahm.Oh Heon Kwon Department of Safety Engineering Pukyong National University Center for Energy Materials Metrology Korea Research Institute or Standards and Science

This paper reports the use of Au films to improve the performance of the stacked solid oxide fuel cell(SOFC) based on the characterization of the interface and the adhesion between the electrodes of the SOFCs and the Ag paste. The specimens were manufactured to perform the experiment as follows. A Si O2 wafer with a 300 mm notch was attached to the electrodes of a SOFC by a Ag paste and Au film, which were deposited on the electrodes by sputtering for 1 min or 5 min deposition time and annealed at300 C for 1 h. The four-point bending test was performed, which resulted in the formation of an extended crack at the tip on the wafer notch, and the crack propagation was observed using a stereo microscope equipped with a charge-coupled device(CCD). Consequently, the interfacial adhesion energy and the effect of the Au film between the each electrode and the Ag paste can be evaluated. On the cathode, the interfacial adhesion energy without Au film was 2.59 J/m2(upper value) and the adhesion energy increased to 11.59 J/m2(upper value) and 15.89 J/m2(lower value) with the Au film. On the anode,the interfacial adhesion energy without Au film was 1.74 J/m2(upper value), which increased to 11.07 J/m2(upper value) and 14.74 J/m2(lower value) with the Au film. In addition, the interface areas were analyzed by scanning electron microscopy(SEM) and energy dispersive spectroscopy(EDS) to estimate the interface delamination.

关键词： Solid oxide fuel cell Au film Interfacial adhesion

Electromagnetically Induced Transparency in an Atom-Molecule Bose-Einstein Condensate

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Communications in Theoretical Physics 2007年第3X期48卷 461-464页

作者： JIN Guang-Ri Chul Koo Kim Kyun nahm Institute of Physics and Applied Physics Yonsei University Seoul 120-749 Korea Department of Physics Yonsei University Wonju 220-710 Korea

We propose a new measurement scheme for the atom-molecule dark state by using electromagnetically induced transparency （FIT） technique. Based on a density-matrix formalism, we calculate the absorption coefficient numerically. The appearance of the EIT dip in the spectra profile gives clear evidence for the creation of the dark state in the atom-molecule Bose--Einstein condensate.

关键词： electromagnetically induced transparency dark state Bose-Einsteln condensate

Artificial synaptic and self-rectifying properties of crystalline(Na_(1-x)K_(x))NbO_(3)thin films grown on Sr_(2)Nb_(3)O_(10)nanosheet seed layers

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Journal of Materials Science & Technology 2022年第28期123卷 136-143页

作者： In-Su Kim Jong-Un Woo Hyun-Gyu Hwang Bumjoo Kim Sahn nahm Department of Materials Science and Engineering Korea UniversitySeoul 02841Republic of Korea KU-KIST Graduate School of Converging Science and Technology Korea UniversitySeoul 02841Republic of Korea

Crystalline(Na_(1-x)K_(x))NbO_(3)(NKN)thin films were deposited on Sr_(2)Nb_(3)O_(10)/TiN/Si(S-TS)substrates at 370°***_(2)Nb_(3)O_(10)(SNO)nanosheets served as a template for the formation of crystalline NKN films at low *** the NKN film was deposited on one SNO monolayer,the NKN memristor exhibited normal bipolar switching characteristics,which could be attributed to the formation and destruction of oxygen vacancy ***,the NKN memristor with one SNO monolayer exhibited artificial synaptic ***,the NKN memristor deposited on two SNO monolayers exhibited self-rectifying bipolar switching properties,with the two SNO monolayers acting as tunneling barriers in the *** conduction mechanism of the NKN memristor with two SNO monolayers in the highresistance state is attributed to Schottky emission,direct tunneling,and Fowler–Nordheim(FN)*** current conduction in this memristor in the low-resistance state was governed by direct tunneling and FN ***,the NKN memristor with two SNO monolayers exhibited large ON/OFF and rectification ratios and artificial synaptic ***,an NKN memristor with two SNO monolayers can be used for fabricating artificial synaptic devices with a cross-point array structure.

关键词： Bipolar switching properties Self-rectifying bipolar switching properties Artificial synaptic properties Crystalline NKN thin film Sr_(2)Nb_(3)O_(10)nanosheet seed layer

Oxcarbazepine for trigeminal neuralgia may induce lower extremity weakness: A case report

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World Journal of Clinical Cases 2020年第5期8卷 922-927页

作者： Hyun-Gul Song Francis Sahngun nahm Department of Anesthesiology and Pain Medicine Seoul Metropolitan Government-Seoul National University Boramae Medical CenterSeoul 07061South Korea Department of Anesthesiology and Pain Medicine Seoul National University Bundang HospitalSeongnam 13620South Korea

BACKGROUND Although few studies have reported hyponatremia due to carbamazepine or oxcarbazepine in patients with epilepsy,no study has investigated cases of carbamazepine-or oxcarbazepine-induced hyponatremia or unsteady gait in patients with neuropathic ***,we report a case of oxcarbazepineinduced lower leg weakness in a patient with trigeminal neuralgia and summarize the diagnosis,treatment,and changes of clinical *** SUMMARY A 78-year-old male with a history of lumbar spinal stenosis was admitted to the hospital after he experienced lancinating pain around his right cheek,eyes,and lip,and was diagnosed with trigeminal neuralgia at the right maxillary and mandibular *** was prescribed oxcarbazepine(600 mg/d),milnacipran(25 mg/d),and oxycodone/naloxone(20 mg/10 mg/d)for four *** years later,the patient experienced symptoms associated with spinal stenosis,including pain in the lower extremities and unsteady *** serum sodium level was 127 mmol/*** oxcarbazepine to be the cause of the hyponatremia,oxcarbazepine administration was put on hold and the patient was switched to *** subsequent visit,the patient’s serum sodium level had normalized to 143 mmol/L and his unsteady gait had *** Oxcarbazepine-induced hyponatremia may cause lower extremity weakness and unsteady gait,which should be differentiated from those caused by spinal stenosis.

关键词： Case report Drug-related side effects and adverse reactions Hyponatremia Oxcarbazepine Spinal stenosis Trigeminal neuralgia