• Journal of the Korea Academia-Industrial cooperation Society
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• v.9 no.2
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• pp.303-310
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• 2008

We fabricated hydrogenated amorphous silicon(a-Si:H) 140 nm thick film on a $180\;nm-SiO_2/Si$ substrate with an inductively-coupled plasma chemical vapor deposition(ICP-CVD) equipment at $250^{\circ}C$. Moreover, 30 nm-Ni film was deposited with a thermal-evaporator sequently. Then the film stack was annealed to induce silicides by a rapid thermal annealer(RTA) at $200{\sim}500^{\circ}C$ in every $50^{\circ}C$ for 30 minuets. We employed a four-point tester, high resolution X-ray diffraction(HRXRD), field emission scanning electron microscope(FE-SEM), transmission electron microscope(TEM), and scanning probe microscope(SPM) in order to examine the sheet resistance, phase transformation, in-plane microstructure, cross-sectional microstructure evolution, and surface roughness, respectively. We confirmed that nano-thick high resistive $Ni_3Si$, mid-resistive $Ni_2Si$, and low resistive NiSi phases were stable at the temperature of <300, $350{\sim}450^{\circ}C$, and >$450^{\circ}C$, respectively. Through SPM analysis, we confirmed the surface roughness of nickel silicide was below 12 nm, which implied that it was superior over employing the glass and polymer substrates.

• Journal of Hydrogen and New Energy
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• v.16 no.4
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• pp.356-363
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• 2005

The purpose of this paper is to investigate the optimal condition of the Syngas production by reforming of fuel using plasmatron. Plasma was generated by air and arc discharge. The effects of applied steam, $CO_2$ or Ni-catalyst on fuel conversion, as well as hydrogen yield and $H_2$/CO ratio were studied. When the variations of $O_2$/fuel ratio, $H_2O$/fuel flow ratio and $CO_2$/fuel flow ratio were $0.94{\sim}1.48$, $4.3{\sim}10$ and $0.8{\sim}3.05$, respectively. Under the condition mentioned above, result of $H_2O$/fuel flow ratio was maximum $H_2$ concentration, or $28.2{\sim}31.6%$, and result of $H_2O$/fuel flow ratio with catalyst was minimum CO concentration or $6.6{\sim}7.1%$. and $H_2$/CO ratio were $3.89{\sim}4.86$.

• Journal of Hydrogen and New Energy
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• v.34 no.6
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• pp.575-580
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• 2023

An electrode was prepared by dip-coating NiFe₂O₄ powder on stainless steel (SUS) support for the application in the alkaline water electrolysis. The prepared electrode was analyzed using scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDXS), and was evaluated for the voltage properties with the change of current density in oxygen evolution reaction (OER) and hydrgen evolution reaction (HER) using 1, 3 and 7 M KOH solution. From the SEM and EDXS analysis, it was confirmed that the prepared electrode had NiFe₂O₄ on the SUS support. In OER and HER, the voltage in the 7 M KOH solution had a value of 1.35 and -1.90 V at 0.2 and -0.2 A/cm² of the current density, respectively. It was considered that the prepared electrode could be use as an electrode in the alkaline water electrolysis from the experimental results.

• Atmosphere
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• v.28 no.3
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• pp.325-336
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• 2018

This study investigates robust features of interdecadal changes in the Northern hemisphere summer tropical-extratropical teleconnection occurred around the mid-to-late 1990s by analyzing four different reanalysis data for atmospheric circulation and temperature, two precipitation reconstructions, and two sea surface temperature (SST) data during the satellite observation era of 1980~2017. For the last 38 years, there has been a significant increasing trend in anticyclonic circulation at lower and upper troposphere and 2 m air temperature with wavenumber-5 Rossby wave structure in the Northern Hemisphere (NH) extratropics. The increase has been accompanied with the significant weakening and northward shift of jet stream over Eurasia and the North Pacific. It is further found that there has been a significant interdecadal shift occurred around the mid-to-late 1990s in the two distinct modes of tropical-extratropical teleconnection: Western Pacific-North America (WPNA) and circumglobal teleconnection (CGT) pattern. After mid-to-late 1990s, the WPNA has played more important role in modulating the extratropical atmospheric circulation and surface climate, which has been preferentially occurred during the El $Ni{\tilde{n}}o$-Southern Oscillation (ENSO) decaying or transition summer such as 1998, 2010 and 2016. During these summers, severe heat waves were occurred over many parts of the NH extratropics due to the combined effect of the increasing trend in the barotropic anticyclonic circulation and the significant WPNA across the NH. Although weakened, the CGT also contributed to some of hot summers over many parts of the NH extratropics such as 1999, 2000, 2008, 2011, and 2012 when weak to moderate La $Ni{\tilde{n}}o$ was persisted.

• Journal of the Korean Chemical Society
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• v.38 no.4
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• pp.295-301
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• 1994

The Ru(Ⅲ), Ni(Ⅱ), Cu(Ⅱ), and Pd(Ⅱ) complexes of N$_4$-polydentate ligands(meso-Me$_6$-[14]-ane, rac-Me$_6$-[14]-ane, and cyclam) have been prepared and their catalytic activity and selectivity in the oxidation of olefins in the presence of oxidant such as NaOCl, H$_2$O$_2$, t-BuOOH, and PhIO studied. The oxidations of cyclohexene, 1-hexene, cyclooctene, 1-octene, and styrene as substrates have been investigated gas chromatographically. The Ru(Ⅲ)-N$_4$ complexes showed high selectivity for epoxide in the catalyzed oxidation of olefins with NaOCl. The catalytic activities of Ru(Ⅲ)-N$_4$ complexes were discussed in terms of the flexibility of N$_4$-polydentate ligands, the Ru(Ⅲ)-Cl bond interaction and the steric effect of oxidants. The oxidation of 1-octene using PhIO as oxidant was carried out to verify. The Pd(Ⅱ) complex turned out to be more active catalyst than the Ni(Ⅱ) complexes.

• The Journal of Korean Academy of Prosthodontics
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• v.23 no.1
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• pp.83-95
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• 1985

The purpose of this study was to evaluate microstructures on the etched surface of 11 base metal alloys for dental restorations and to observe the relationship between the etching pattern and beryllium. For this purpose, the following experiments were done; 11 base metal alloys were etched in (1) 10% $H_2SO_4$, (2) 10% $H_2SO_4$, 9 parts+methanol 1 part (3) Conc. $HNO_3$ 25%+glacial acetic acid 25%+$H_2O$ 50% (4) Conc. $HNO_3$ 5% (5) 2% glacial acetic acid added to Conc. $HNO_3$ 1% solution, with their etching conditions varied. Etched surface of alloys were examined under the scanning electron microscope. Results were as follows; 1. Almost all of Ni-Cr-Be alloys showed gooed etchd surface in $H_2SO_4$, solution, while some of those alloys which contains no beryllium showed good etched surface in $HNO_3$ solution. 2. Main components of etching solution can vary etching pattern of alloys. 3. Gamma prime phase relief, which can be found in all Ni-Cr-Be alloys, can't be found in any alloy that contains no beryllium.

• Proceedings of the Korean Vacuum Society Conference
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• 2010.08a
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• pp.210-210
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• 2010

ABO2 형태를 가진 delafossite 구조 산화물은 p-type 투명전도체 소재로 유명하다. Delafossite 구조가 p-type 투명전도체에 적합한 결정적인 이유는 밴드갭이 넓고 공유결합에 유리하기 때문이다. 투명전도체는 가시광선의 흡수가 없도록 band gap을 넓히는 것이 우선인데 이러한 band gap이 넓은 구조가 delafossite이다. 또한 delafossite 구조는 구조적으로 각각의 산화물 이온들이 유사 사면체 배위(pseudo-tetrahedral coordination)을 갖는다. 이러한 사면체 배위결합구조에서 산소이온은 비결합면이 없기 때문에 더욱더 공유결합성을 향상시킬 것으로 생각된다. 여기서 A는 +1가 cation, B은 +3가 cation으로 구성되어 있다. A자리에는 1가 원소인 팔라듐, 플래티늄, 은, 구리 등을 가질 수 있고. B자리에 3가 원소이면서도 크기가 알루미늄보다는 크고 란타늄보다는 작은 금속이 들어갈 수 있다. Delafossite 구조는 상온에서 2종류의 polytype (상온에서 Rhombohedaral 구조와 hexagonal 구조)이 존재하며 이들은 각각 3R(Rm) 및2H (P63/mmc)의 결정 구조를 가지고 있다. CuCrO2는 일반적으로 3R결정구조를 가지는 것으로 알려져 있다. delafossite 구조는 전기적 이방성을 띄고 있는데 c-축 방향으로의 전기적 특성이 a-축 방향으로의 전기적 특성보다 약 1000배 높은 물성을 띈다고 한다. 이는 c-축 방향의 원자 위치 때문인데 CuCrO2의 경우 Cu-O-Cr-O-Cu로서 3d-2p-3d-2p-3d 궤도를 가지기 때문인 것으로 알려져 있다.[ref] 반면 c-축으로 에피성장된 박막의 경우 +3가 이온이 위치한 layer에서 hole hopping에 의해 캐리어가 전도된다고 알려져 있기도 하다. 본 연구에서는 PLD를 이용하여 c-plane 사파이어 기판위에 성장된 delafossite구조인 CuCrO2박막의 특성을 알아보았다. p-type 특성을 위하여 CuCrO2에 Ni를 첨가하였으며 그에 따른 구조적 전기적 특성을 조사하였다. 성장온도와 도핑농도를 변화시켜 특성을 연구하였다. 결정구조적 특성과 전기적 특성을 분석하려 한다.

• Journal of the Korean Society of Clothing and Textiles
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• v.33 no.6
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• pp.853-859
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• 2009

Endometriosis becomes the most common cause of pelvic pain and infertility women. The cause of endometriosis has ever been entirely proven. However, an increased use of commercial feminine hygiene products such as tampons and sanitary napkins was considered one of the major affect. Harmful substances in feminine hygiene products was analyzed and evaluated. Samples of commercial products obtained from Korea, Japan, America, Germany, and China were analyzed for six hazardous inorganic elements (chromium, cobalt, nickel, copper, cadmium and lead). In the extractable heavy metals of napkins, Cr, Ni and Cu were found in all of the samples, while Cd was detected only in two samples. In the tampons, Cr, Ni and Cu were found in all of the samples. The presence of Co and Cd was not detected in all samples The concentrations of extractable heavy metals in the tampons were lower than those in the sanitary napkins. The content of extractable heavy metals in the sanitary products was compared with the criteria of the 100 $\ddot{O}KO$ TEX Standard. It was confirmed that the level of heavy metals in the sanitary products posed no serious risk to health, based on the human-ecological criteria defined by the 100 $\ddot{O}KO$ TEX Standard.

• Bulletin of the Korean Chemical Society
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• v.21 no.3
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• pp.317-320
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• 2000

Layered $K_2NiF_4$type ($C_nH_{2n+1}NH_3)_2PbCl_4$(n=6, 8 and 10) system, or alkylammonium tetrachloroplumbate compound, has been synthesized from $PbCl_2$ and $C_nH_{2n+1}NH_3Cl$ solutions under argon ambient pressure for 12hrs at $90^{\circ}C$. The crystal structure of the compound has been analyzed using X-ray powder diffaction in the range of $5^{\circ}{\leq}2{\theta}{\leq}55^{\circ}$, and all samples assigned to an orthorhombic system. Local distances of the Pb-Cl bond have been determined by Pb $L_{III}$-edge extended X-ray absorption fine structure (EXAFS) spectroscopy. The vibration modes of alkylammonium chains and the absorpton peaks of an excition have been examined by FT-IR and UV-Vis. reflectance spectra, respectively. The phase transition temperatures of the compounds have been studied by using DSC. According to the thermal analysis, two phase transition temperatures have been observed in the compositons of n=8 and 10.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.10 no.3
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• pp.334-342
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• 1998

In this experimental study, methanol was chosen as a system material for a long -distance heat transportation. Not only transition metals but also noble metals were investigated as an active component, and several metal oxides, such as ${\gamma}$-$Al_2$,$O_3$, $SiO_2$, etc. as a support. In general, transition metal catalysts absorbed more heat than noble metal catalysts. The amount of heat absorption and CO selectivity depends on temperature and methanol partial pressure, and 25$0^{\circ}C$ Ni/$SiO_2$ catalyst showed the best result for methanol decomposition reaction.