• Proceedings of the Korean Magnestics Society Conference
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• 1992.03a
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• pp.100-101
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• 1992

• Journal of the Mineralogical Society of Korea
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• v.18 no.3 s.45
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• pp.147-153
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• 2005

Naldrettite, recently discovered in the Mesamax Northwest deposit, Ungava region, northern Quebec, Canada, was reported as a new mineral. In order to confirm whether itis a natural equivalent of synthetic $Pd_2Sb$ phase or not, the pure $Pd_2Sb$ phase has been synthesized and investigated by reflected microscope, electron microprobe analyser, X-ray diffractometer, and micro-indentation hardness tester. Under reflected light synthetic $Pd_2Sb$ Phase is white with a creamy tint in both air and oil and weakly bireflectant. Anisotropism is strong, from brownish gray to greenish blue in air. Micro-indentation hardness test gives VHN100=293(242-322). Composition of the phase is $63.7\~64.3wt.\%\;Pd\;and\; 36.4\~36.8wt.\%$ Sb, and is entirely consistent. The phase, quenched from $500^{\circ}C$, is orthorhobic with space group $Cmc2_1$, and the cell parameters are a=3.366(1), b=17.523(3), c=6.929(2) ${\AA}$. All mineralogical properties of synthetic $Pd_2Sb$ compare very well with those of naldrettite, confirming that naldrettite is the natural analogue of the synthetic $Pd_2Sb$ phase.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.05b
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• pp.100-103
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• 2004

In this paper, BP learning algorithm is studied to apply as a PD source classification in GIS specimens. For occurred partial discharge, three defected models are made; floating particle, surface discharge of spacer, needle to plane. And PD data for discrimination were acquired from PD detector. And these data making use of a computer-aided discharge analyser, statistical and other discharge parameters is calculated to discrimination between different models of discharge sources. And also these parameter is applied to classify PD sources by neural networks. Neural Networks has good recognition rate for three PD sources.

• Journal of Energy Engineering
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• v.19 no.1
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• pp.21-24
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• 2010

We present a novel electrochemical method to fabricate a single Pd nanowire based on direct current assisted dielectropheresis (DEP) process between two predefined metal electrodes. The electrochemical methods was investigated as functions of frequency and voltage for optimal growth conditions of Pd nanowire. The synthesized Pd nanowire have a good resistance of $1\;k{\Omega}$, diameters of several hundred nanometers on average and lengths of $8\;{\mu}m$. Finally, the single Pd nanowire was capable of detecting hydrogen in the concentration range from 100 to 2500 ppm with high sensitivity and response time, thus demonstrating its suitability for use as a hydrogen sensor.

• Journal of Electrical Engineering and Technology
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• v.4 no.1
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• pp.123-130
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• 2009

The partial discharge (PD) measurement is a very effective method to assess the winding insulation condition of high-voltage machines, since most of the insulation failure processes are directly or indirectly caused by PD. On-line PD measurements, which can detect insulation defects of winding in the early stages on rotating machines in operation, have been accepted as the most important technique. The epoxy mica capacitive coupler is currently and extensively used for on-line detection of PD pulses of high-voltage rotating machines. To evaluate the feasibility of developing a capacitive coupler that is easier to manufacture at a lower cost compared to epoxy mica couplers, a 100pF capacitive coupler made of ceramic material is designed, fabricated and tested for on-line PD measurements of 23 kV electrical machines. A series of electrical tests and accelerated aging tests are performed on the ceramic coupler to evaluate the performance requirements, long-term reliability and thermal stability for in field application. The test results show that the newly developed ceramic coupler provides equal and improved performance at a lower cost compared to epoxy mica couplers, and estimated voltage life is anticipated to surpass 100 years.

• Proceedings of the Korean Vacuum Society Conference
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• 2000.02a
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• pp.145-145
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• 2000

M-CeO2 (M : noble metal) catalysts have been widely studied as three-way catalysts and methanol synthesis catalysts. Ceria is thought to play a number of roles in these catalysts. The Ce(IV)/Ce(III) redox pair may store/release gases under oxidizing/reducing conditions, extending the operational window. Additionally, metal-ceria interactions lead to several effects, including the dispersion of the active components and promoting the activation of molecules such as CO or NO. Pd is a promising component to current TWC formulations and behaves particularly well when compared with Pt and Rh-based catalysts for low-temperature oxidation of Co and hydrocarbon. However the effect of Pd-ceria interactions on the physicochemical properties of Pd and the redox properties of Ce is not elucidated yet. In order to know exactly about the metal-ceria interactions, the model study are expecting to give a better environment, resulting in the wide use of the surface science tools. The substrate was Si(100) wafer, on which Ta metal was sputtered as a thickness of 100nm. The CeO2 thin film of 30nm was deposited by using the magnetron sputtering. Spin coating and magnetron sputtering methods were used to make the Pd thin film layer. The prepared sample was investigated by in-situ XPS, AES, SEM and AFM analysis.

• Journal of Biomedical Engineering Research
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• v.20 no.6
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• pp.539-546
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• 1999

현재 상용화되고 있는 치과용 76.5% Pd-11.2% Cu-7.2% GarP 합금의 왁스모형을 원심주조기로 주조하여, 임상조건의 탈개스 및 세라믹 소성처리를 하였다. 이에따른 각각의 시편에 대해 미세조직의 변화를 주사전자현미경 및 EDS로 관찰하고, 최종적인 투과전자현미경으로 조사하였다. 각 조건의 편석, 결정립계 및 석출물부위를 주사전자현미경과 EDS 고 관찰한 결과, 이원계 Pd-GA합금의 안정상들에 해당하는 정량적인 조성비는, 단지 상대적으로 Ga의 성분비만 높게 감지되었다. 특히, 세라믹소성 처리후 미세조직에서 형성된 석출물에 근접한 기지조직일수록 Ga의 농도가 상대적으로 줄어든 고갈현상을 확인하엿다. 또한 투과전자현미경의 제한시야회절도형 분석결과, 주조 및 탈개스처리 후 미세조직의 편석부위에서는 GA의 가장 큰 강도를 보였고, 또 Ga과 Pd 고용체 사이에 미세한 판상의 석출물에 기인하는 줄무늬를 관찰하였다. 한편, 세라믹소성처리후 미세조직의 석출물은 금속간화합물 Pd2Ga으로 밝혀졌으며, 기지조직은 <100> 방향을 따라 약 25nm의 폭을 가지는 미세한 섬유상 형태의 소위 "tweed 조직'을 형성하였다.성하였다.

• Korean Journal of Materials Research
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• v.10 no.4
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• pp.295-300
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• 2000

Uniform silicon tip arrays were fabricated using the reactive ion etching followed by the reoxidation sharpening, and the effect of Pd-coated layer on electron emission characteristics was studied. The electron emission from Si field emitter arrays(FEAs) was a little, but improved by removing surface oxide on the FEA, but pronounced drastically by coating a $100-{\AA}-thick$ Pd metal layer. The turn-on voltage in the Pd-coated Si FEAs was reduced by 30 V in comparison with that in uncoated ones. This results from the increase of surface roughness at the tip apex by the Pd coating on Si FEA, via the decrease of the apex radius at which electrons are emitting. The Pd-coated emitters showed superior operating stability over a wide current range to that of the uncoated ones. This suggests that Pd coating enhances the high temperature stability and the surface inertness Si FEA.

• Journal of Ginseng Research
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• v.17 no.3
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• pp.187-195
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• 1993

We have examined the functional role of central dopaminergic processes on the behavioral pharmacological effects induced by psychotropics and red ginseng saponins of normal rats and compared with that of brain damaged rats. Desipramine and clomipramine produced, a significant depression of the locomotor activity in normal rats, but in brain damaged rats, they did not have any effect throughout the experimental period of 4 hours. Total saponin (50~200 mg/kg), PT (25~50 mg/kg), PD (25~50 mg/kg), $Rg_1$(12.5~25 mg/kg), $Rb_1$ (12.5~50 mg/kg) did not change, and high concentrations of PT (100 mg/kg), PD (100 mg/kg) and $Rg_1$ (50 mg/kg) showed a significant decrease in the locomotor activity of one hour after administration but total saponin (100 mg/kg), PD (25~50 mg/kg), Rgl (12.5 mg/kg), $Rb_1$ (12.5 mg/kg) markedly increased the locomotor activity of four hour after administration in normal rats. On the other hand, total saponin (50 mg/kg), PT (100 mg/kg) and PD (100 mg/kg) Produced a prominent stimulation of the locomotor activity in brain damaged rats. These results suggest that the inhibition of the locomotor activity induced by antidepressants was not affected by the sensitivity of cerebral DA system, whereas red ginseng saponin showed antifatigue effect and also the stimulation of the locomotor activity induced by red ginseng saponin was mediated by the inhibition of cerebral DA system. These psychotropic action of red ginseng saponins could be responsible for the beneficial effects on conditions of fatigue and decreased alertness.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.13 no.12
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• pp.6187-6195
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• 2012

Recycling process of iron should be developed for efficient recovery of neodymium(Nd), rare metal, from acid-leaching solution of neodymium magnet. In this study, $FeCl_3$ solution as iron source was used for synthesis of iron nanoparticle with the condition of various factors, etc, reductant, surfactant. $Na_4O_7P_2$ and polyvinylpyrrolidone(PVP) as surfactants, $NaBH_4$ as reductant, and palladium chloride($PdCl_2$) as a nucleation seed were used. Iron powder was analyzed with instruments of XRD, SEM and PSA for measuring shape and size. Iron nanoparticles were made at the ratio of 1 : 5(Fe (III) : $NaBH_4$) after 30 min of reduction time. Size and shape of iron particles synthesized were round-form and 50 nm ~ 100 nm size. Zeta-potential of iron at the 100 mg/L of $Na_4O_7P_2$ was negative value, which is good for dispersion of metal particle. When $Na_4O_7P_2$(100 mg/L), PVP($FeCl_3$ : PVP = 1 : 4, w/w) and Pd($FeCl_3$ : $PdCl_2$ = 1 : 0.001, w/w) were used, iron nanoparticles which are round-shape, well-dispersed, near 100 nm-sized can be made.