• Journal of the Korea Institute of Military Science and Technology
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• v.20 no.5
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• pp.654-664
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• 2017

The temperature profiles upon high speed impact of reactive structural materials were analyzed. A two color pyrometer, which included high-speed camera, spectral splitter, and band pass filters, was utilized to measure transient temperature profiles during and after reactive metal samples impacted into steel plate with velocities of 1600~1700 m/s. The spatial temperature distribution was analyzed from the ratio of spectral radiances at two different wavelength in infrared zone, i.e. 700 and 900 nm. The measured temperatures were calibrated with black body source. Two different types of metal samples, namely aluminum and nickel, were employed to understand reaction behavior upon the impact of samples in ambient condition. According to our experiments, the Ni sample appeared to barely react with ambient air producing an instant small fireball, while Al sample reacts violently with air generating a relatively prolong fireball.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.53 no.10
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• pp.495-499
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• 2004

Characteristics of ohmic Ni/Si/Ni contacts to n-type 4H-SiC are investigated systematically. The ohmic contacts were formed by annealing Ni/Si/Ni sputtered sequentially The annealings were performed at 950℃ using RTP in vacuum ambient and N₂ ambient, respectively. The specific contact resistivity(p/sub c/), sheet resistance(R/sub s/), contact resistance (R/sub c/) transfer length(L/sub T/) were calculated from resistance(R/sub T/) versus contact spacing(d) measurements obtained from TLM(transmission line method) structure. While the resulting measurement values of sample annealed at vacuum ambient were p/sub c/ = 3.8×10/sup -5/Ω㎠, R/sub c/ = 4.9 Ω and R/sub T/ = 9.8 Ω, those of sample annealed at N₂ ambient were p/sub c/ = 2.29×10/sup -4/Ω㎠, R/sub c/ = 12.9 Ω and R/sub T/ = 25.8 Ω. The physical properties of contacts were examined using XRD 3nd AES. The results showed that nickel silicide was formed on SiC and Ni was migrated into SiC. This result indicates that Ni/Si/Ni ohmic contact would be useful in high performance electronic devices.

• Proceedings of the KSME Conference
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• 2004.11a
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• pp.90-95
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• 2004

The probabilistic fracture analysis is used to determine the effects of uncertainties involved in material properties, location and size of flaws, etc, which can not be addressed using a deterministic approach. In this paper the probabilistic fracture analysis is applied for evaluating the RV(Reactor Vessel) under PTS(Pressurised Thermal Shock). A semi-elliptical axial crack is assumed in the inside surface of RV. The selected random parameters are initial crack depth, neutron fluence, chemical composition of material (copper, nickel and phosphorous) and $RT_{NDT}$. The deterministically calculated $K_I$ and crack tip temperature are used for the probabilistic calculation. Using Monte Carlo simulation, the crack initiation probability for fixed flaw and PNNL(Pacific Northwest National Laboratory) flaw distribution is calculated. As the results show initiation probability of fixed flaw is much higher than that of PNNL distribution, the postulated crack sizes of 1/10t in this paper and 1/4t of ASME are evaluated to be very conservative.

• Proceedings of the Materials Research Society of Korea Conference
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• 2003.11a
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• pp.216-216
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• 2003

The layered nickel oxides (LiNiO$_2$) have been studied for possible use as cathode materials i3l 4V lithium batteries. Although LiCoO$_2$ has been known as the best candidate material for Li-ion batteries, which produces the best performance LiNiO$_2$ is generally accepted as an attractive cathode material, because of its various advantages such as lower cost higher discharge capacity and better reversibility. In this investigation, we calculated the electric state of LiNiO$_2$ using DV-X$\alpha$ molecular orbital method in order to obtain the information of chemical bonding among the Li, Ni and O. In LiNiO$_2$, alternate layers of Li and Ni occupy the octahedral sites of a cubic close packing of oxide ions, making up a rhombohedral structure with an R-3m space group, Li in 3a, Ni in 3b, and O in 6c sites. On the basis of this, we made the cluster model and studied ionization of each atoms and interaction between atoms according to Mullilcen population analysis.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.27 no.9
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• pp.547-550
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• 2014

In this study, the electrical characteristics of the nickel (Ni)/carbon nanotube (CNT)/$SiO_2$ structures were investigated in order to analyze the mechanism of CNT in MOS device structures. We fabricated 4H-SiC MOS capacitors with or without CNTs. CNT was dispersed by isopropyl alcohol. The capacitance-voltage (C-V) and current-voltage (I-V) are characterized. Both devices were measured by Keithley 4200 SCS. The experimental flatband voltage ($V_{FB}$) shift was positive. Near-interface trap charge density ($N_{it}$) and negative oxide trap charge density ($N_{ox}$) value of CNT embedded MOS capacitors was less than that values of reference samples. Also, the leakage current of CNT embedded MOS capacitors is higher than reference samples. It has been found that its oxide quality is related to charge carriers and/or defect states in the interface of MOS capacitors.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.55 no.11
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• pp.544-547
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• 2006

In this paper, we present a temperature-controlled system for MEMS electrical resistance heaters without a temperature sensor. To rapidly control the heater temperature, the microheater system developed consists of a power supply, power amplifier, digital ${\underline{P}}roportional-{\underline{I}}ntegral-{\underline{D}}ifferential$ (PID) controller, and a quarter bridge circuit with the microheater and three resistors are nominally balanced. The microheaters are calibrated inside a convection oven to obtain the temperature coefficient with a linear or quadratic fit. A voltage amplifier applies the supply voltage proportional to the control signal from the PID controller. Small changes in heater resistance generate a finite voltage across the quarter bridge circuit, which is fed back to the PID controller to compare with the set-point and to generate the control signal. Two MEMS microheaters are used for evaluating the developed control system - a NiCr serpentine microheater for a preconcentrator and a Nickel microheater for ${\underline{P}}olymerase\;{\underline{C}}hain\;{\underline{R}}eaction$ (PCR) chip.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2001.04a
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• pp.172-181
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• 2001

Upflow anaerobic sludge blanket (UASB) system employs granular sludge to treat various wastewaters including landfill leachate. CH$_4$ production of the granules determines overall performance of a UASB reactor. Sludge granules are developed by self-granulation of microorganisms and dynamic balance between granule growth and decay results in coexistence of granules with different sizes in the reactor. In this study, granules taken from a laboratory-scale UASB reactor were classified into 4 groups based on their diameters and their Physicochemical characteristics we were investigated. Each group was analyzed for settling ability, specific methanogenic activity (SMA), and elemental content. Settling ability was proportional to granule diameter. suggesting effective detainment of larger granules in the reactor. When acetate or glucose was used as a substrate, all groups showed relatively slight difference in SMA. However SMA with a volatile fatty acid mixture showed significant increase with granule diameter, suggesting better establishment of syntrophic relationship in larger granules. Larger granules showed higher value of SMA upon environmental changes (i.e., PH, temperature, or toxicant concentration). Comparative analysis of elemental contents showed that content (dry weight %) of most tested elements (iron, calcium, phosphorus, zinc, nickel. and manganese) deceased with granule diameter, suggesting importance of these elements for initial granulation. Taken together, this study verified experimentally that Physicochemical Properties of granules are related to granule size distributions. Overall results of physicochemical characterization supports that larger.

• Journal of the Korean Chemical Society
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• v.31 no.3
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• pp.231-235
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• 1987

In 10M chloride (4M HCl + 6M LiCl) solution, cobalt, but not nickel, formed complex anion (${CoCl_3}^-$), and this anion was extracted by a liquid anion exchanger with Amberlite LA-2. The ion exchange capacity was 2.175meq of cobalt complex per unit ml of Amberlite LA-2. Upon eluting the resin with 0.4M nitric acid, the cobalt complex was stripped and transfered into eluate quantitatively. By using this separation method in the chloride solution dissolved with 50mg of cobalt (II) and 500mg of nikel(II), recovery of cobalt were 99.6 percent.

• Journal of Technologic Dentistry
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• v.5 no.1
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• pp.19-26
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• 1983

I got a conclusion as a result of that in case of constructing a full denture using acrylic resin teeth, porcelain teeth, and forming posterior occlusal surface of the artificial teeth by Type III Gold and Nickel crome alloy thus construdting a full denture and therefore comparing the above case with abrasion of Natural teeth. The result were as follows : 1. The abrasion of Natural teeth and the abrasion of full denture constructed by Type III gold has a close resemblance. 2. The one that has the hightest degree of abrasion is full denture that's using, with acrylic resin teeth, maxillary and mandibular And the lowest abrasion is natural teeth-natural teeth. 3. In case of single denture, that's opposing to natural teeth, the one that has the hightest degree of abrasion is a full denture that's using Acrylic resin teeth and the lowest abrasion is a full denture that's forming occlusal surface by Type III gold. 4. The single denture, which is opposing to type III gold teeth, was abraded above everything by full denture which is constructed by porcelain teeth. 5. In the same teeth, the abrasion of mandibular teeth was greater than that of mandibular teeth was greater than that of maxillary teeth. 6. The abrasion degree of Acrylic resin teeth has no direct mutual connection with material hardness which is opposing to.

• Proceedings of the Korean Society of Applied Pharmacology
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• 2001.11a
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• pp.91-91
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• 2001

Nramp2, also known as DMT1 and DCT1, is a 12-transmembrane domain protein responsible for dietary iron uptake as well as metal ions such as lead, manganese, zinc, copper, nickel, cadmium, and cobalt. High expression of DMT1 increase lead uptake, and DMT1-dependent lead transport was H -dependent and inhibited by iron ions. The molecular mechanism of lead transport in CNS is as yet unknown. although interactions between iron and lead at the level of absorption have been known for some time. The process of lead uptake into astrocytes was not known yet. Nramp2 may mediate transport of heavy metal into astrocytes. We investigated whether Nramp2 mediate transport of lead into astrocytes. And we do whether Nramp2 was expressed highly by deprivation of iron in Astrocytes, and lead uptake into astrocytes was influenced by expression of Nramp2. Immortalized human fetal astrocyte(SV-FHA) cells were cultured in medium containing Dulbecco's modified Eagle's medium and treated with Deferoxamine. Northern blot analysis was done for determining mRNA level of DMT1 and lead uptake assay was done in incubation condition of pH 5.5 and 7.4.