• Journal of the Korean Applied Science and Technology
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• v.32 no.3
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• pp.461-468
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• 2015

Simultanious quantitative determination of Cetyltrimetyl ammonium chloride(CTM), Stearamidopropyl dimetylamine(SAP), Behentriammonium chloride(BHT), Dihexadeyldimethyl ammonium chloride(DHDDM) was carried out by reversed phase HPLC. The 0.2% TFA/Methanol was used for the mobile phase of gradient conditions. An Alltech $C_{18}$($250mm{\times}4.6mm$ i.d., $5{\mu}m$)and the selected ELSD detector was applied. The analysis results of HPLC showed good linearity with correlation coefficient of $r^2=0.997$ in the rage of $130{\sim}1980.5{\mu}g/mL$ and detection limit.

• Journal of the Korean Ceramic Society
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• v.47 no.6
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• pp.598-602
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• 2010

When metal oxides are added into crystalline glaze, colors of glaze and crystals are similar as colorants generally. But the case of NiO in zinc crystalline glaze is different from general color development. When NiO is added to zinc crystalline glaze it can develop two or three colors. The active use of color development mechanism by adding NiO to the zinc crystalline glaze to control color of the base glaze and crystal with stability is investigated. This report is expected to contribute to the ceramic industry in improving application of zinc crystalline glaze. For the experiment of NiO, the quantity of NiO additives is changed to the base glaze for the most adequate formation of willemite crystal from previous research and firing condition: temperature increasing speed $5^{\circ}C/min$, holding 1 h at $1270^{\circ}C$, annealing speed $3^{\circ}C/min$ till $1170^{\circ}C$, holding 2 h at $1170^{\circ}C$ then naturally annealed. The samples are characterized by X-ray diffraction (XRD), UV-vis, and Micro-Raman. The result of the procedure as follows; Ni substitutes for Zn ion then glaze develops blue willemite crystals, as if cobalt is used, on brown glaze base. When NiO quantity is increased to over 5 wt%, willemite size is decreased, and the density of the crystal is increased, at the same time $Ni_2SiO_4$ (olivine) phase, the second phase, has been developed. The excessive NiO is reacted with silicate in the glass then developed green $Ni_2SiO_4$ (olivine), and quantity of $Ni_2SiO_4$ (olivine) is increased as quantity of willemite is decreased. It is proved to create three colors, blue, brown and green by controlling the quantity of NiO to the zinc crystalline glaze and it will improve the multiple use of colors to the ceramic design.

• Journal of Technologic Dentistry
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• v.40 no.3
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• pp.125-131
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• 2018

Purpose: Automatic dental prosthesis manufacturing process was accelerated by the spread of dental CAD / CAM system. The CAD / CAM system with milling alloys were needed supplement. So, sintered alloy blocks were introduced. In this study, we want to study sintered alloy block. And to evaluate the alloy block manufacture and alloy properties. Methods: The alloy powders were prepared by high pressure water dispersion method. The sintered alloy blocks were prepared by low temperature pressing method. Their components observation were EDX, and the alloy structure was observed by XRD. Results: Co-Cr alloy powders were observed to have a circle shape with an average diameter of about $100{\mu}m$ and a Ni-Cr alloy powder had a circle shape with an average diameter of about $50{\mu}m$. The Co-Cr alloy block is composed of Co (34.62 wt%), Cr (17.33 wt%), Mo (2.98 wt%), Si (0.36 wt%) and C (44.17 wt%). The Ni-Cr alloy powder was composed of Ni (40.29 wt%), Cr (19.37 wt%), Mo (3.53 wt%), Si (0.52 wt%) and C (33.18 wt%). The peak of the Co and CoCr peaks were observed in the CoCr alloy body by the means of XRD study. Cr2Ni3 of the peak was observed in the Ni-Cr alloy material. Conclusion : As a result, the following conclusions were obtained. 1. Prepared by high-pressure water-law Co-Cr alloy powder has an average diameter $100{\mu}m$, Ni-Cr alloy powder was found to have the form of sphere having an average diameter $50{\mu}m$. 2. Co-Cr alloy and Ni-Cr alloy block produced by low-temperature processing showed a certain ratio. 3. In the XRD study, Co phase appeared in Co-Cr alloy block after sintering. and Cr2Ni3 phase appeared in Ni-Cr alloy block after sintering.

• Applied Chemistry for Engineering
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• v.8 no.3
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• pp.410-415
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• 1997

Fibrious potassium hexatitanate whisker was produced from the calcination process using a mixture of the natural rutile ore and industrial $K_2CO_3$. Fibrous Potassium titanate was prepared by the following procedures the starting material consisting of $K_2O{\cdot}4.4TiO_2$ was calcined at $1050^{\circ}C$ for 3 hrs. The calcined products obtained under the above condition consisted mainly of potassium hexatitanate with a small admixture of potassium dititanate and potassium tetratitanate. Therefore the single phase of potassium hexatitanate was obtained by heat treatment of $850^{\circ}C$, 3 hrs.

• Asian Pacific Journal of Cancer Prevention
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• v.13 no.10
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• pp.5037-5042
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• 2012

Background: Tobacco contains agents which generate various potent DNA adducts that can cause gene mutations. Production of DNA adducts may be neutralized by glutathione S transferase (GST) along with other phase I and phase II enzyme systems. The existence of null type of GST among the population increases the susceptibility to various disorders and diseases. The present study focuses on the impact of high tobacco usage and possible null type mutation in GST loci. Methods: Genotypes of GST were detected by multiplex polymerase chain reaction in unrelated 504 volunteers of high tobacco using natives of Gujarat. Allelic frequencies were calculated using Statistical Package for Social Studies-16 software. Hardy Weinberg Equilibrium (HWE) was calculated using Chi square test. Two sided Fisher's significance test was used to compare allelic frequencies of different populations. Results: The frequency of homozygous null genotype of GSTM1 and GSTT1 were 20% (95% CI 16.7-23.9) and 35.5% (95% CI 31.4-39.9) respectively. The GSTM1 and GSTT1 null allele frequency distribution in the Gujarat population was significantly deviating from HWE. GSTT1 null frequency of Gujaratians was significantly higher and different to all reported low tobacco using Indian ethnics, while GSTM1 was not differing significantly. Conclusion: Tobacco usage significantly influences the rate of mutation and frequency of GSTT1 and M1 null types among the habituates. The rate of mutation in GSTT1 loci was an undeviating response to the dose of tobacco usage among the population. This mutational impact of tobacco on GSTT1 postulates the possible gene - environment interaction and selection of null genotype among the subjects to prone them under susceptible status for various cancers and even worst to cure the population with GSTT1 dependent drugs.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.34 no.5
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• pp.471-479
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• 2010

The adiabatic two-phase flow in single rectangular microchannels was studied for different aspect ratios. The working fluids were liquid water and nitrogen gas. The hydraulic diameters of the rectangular microchannels were 490, 322, and $143\;{\mu}m$, and the widths of the microchannels were around $500\;{\mu}m$. The two-phase flow pattern was visualized using a high-speed camera and a long-distance microscope. This study was focused on bubble flow regimes. From the visualized images, the bubble velocity, bubble length, number of bubbles, and void fraction were evaluated. Further, the pressure drop in a single bubble was evaluated by using a unit cell model. The bubble velocity is proportional to the superficial velocity. Further, the relationship between the void fraction and the volumetric quality is linear. The pressure drop in a single elongated bubble is strongly related to the aspect ratio. Finally, the new correlation about the pressure drop of a single elongated bubble in the rectangular microchannel was proposed.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.16 no.9
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• pp.795-800
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• 2003

The dielectric and piezoelectric properties of the xPb(A $l_{0.5}$N $b_{0.5}$) $O_3$-(1-x)Pb(Z $r_{0.52}$ $Ti_{0.48}$) $O_3$ [xPAN-(1-x)PZT] thin films by pulsed laser deposition (PLD) were investigated as a function of PAN contents. The effect of texture on dielectric and piezoelectric properties of the 0.05PAN-0.95PZT thin films having the highest piezoelectric constant( $d_{33}$) was studied more precisely. For 0$\leq$x$\leq$0.15 compositions in xPAN-(1-x)PZT thin films, the well-developed perovskite phase with (111) preferred orientation was obtained at the deposition temperature of 50$0^{\circ}C$. With increasing PAN content, remanent polarization and coercive field decreased. The dielectric constant increased with an increase of PAN content until it reached 1450 at $\chi$= 0.05, and then decreased for higher PAN content. The maximum points of dielectric constant coincides with the maximum points of the piezoelectric constant $d_{33}$.33/.33/././.

• Corrosion Science and Technology
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• v.3 no.5
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• pp.198-208
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• 2004

Although there has been no general agreement on the mechanism of primary water stress corrosion cracking (PWSCC) as one of major degradation modes of Ni-base alloys in pressurized water reactors (PWR's), common postulation derived from previous studies is that the damage to the alloy substrate can be related to mass transport characteristics and/or repair properties of overlaid oxide film. Recently, it was shown that the oxide film structure and PWSCC initiation time as well as crack growth rate were systematically varied as a function of dissolved hydrogen concentration in high temperature water, supporting the postulation. In order to understand how the oxide film composition can vary with water chemistry, this study was conducted to characterize oxide films on Alloy 600 by an in-situ Raman spectroscopy. Based on both experimental and thermodynamic prediction results, Ni/NiO thermodynamic equilibrium condition was defined as a function of electrochemical potential and temperature. The results agree well with Attanasio et al.'s data by contact electrical resistance measurements. The anomalously high PWSCC growth rate consistently observed in the vicinity of Ni/NiO equilibrium is then attributed to weak thermodynamic stability of NiO. Redox-induced phase transition between Ni metal and NiO may undermine the integrity of NiO and enhance presumably the percolation of oxidizing environment through the oxide film, especially along grain boundaries. The redox-induced grain boundary oxide degradation mechanism has been postulated and will be tested by using the in-situ Raman facility.

• Journal of the Korea Furniture Society
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• v.20 no.5
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• pp.467-479
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• 2009

The high-tech computer technology developments have greatly affected the area of design education. Starting from the mid 80s, innovations in visual presentation methods have heightened with 2D computer graphic programs, CAD & 3D modeling, and Rapid Prototype that allows dimensional generation. The specialty and quality in design studio education have advanced due to the development in presentation methods such as Power Point and Keynote. But there are many problems with the current method of presenting the visual outcome in a data format using beam projectors, which is a vertical presenting method compared to the old studio study method of conducting discussions and reviews based on the substantial outcome. The essence of studio study that allows for comparisons and analysis by horizontally opening up the various work outcomes is being offset. Also the requirement for manual idea sketching work that plays an important role in the initial design phase continuing to decrease due to the digital working process dependence and cumbersome procedures in the presentation. In order to resolve this problem, the CALM system (Class Applied LCD Modular System) has been developed that replaces the method of attaching the sketches or renderings on the wall with a digital multi-display system. In a nutshell, individuals will upload the outcomes online and display them on the CALM system studio that is composed of 32 LCD (Columns: 4 $\times$ Rows: 8) monitors that are 19 inches in size so that various personnel can openly study the design outcomes. Also the central 42 inch PDP monitor that offers touch pad capability allows each design outcome to be described and examined by expanding. The concept phase of this development process has elevated to the production of an operating prototype that is being reviewed of its practicality. It is considered that the development of this system will decrease the extreme tendency of depending on digital operation but achieve revitalization of a more realistic and opened studio study environment compared to the individual consulting method of the old study approach.

• Applied Biological Chemistry
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• v.47 no.2
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• pp.164-169
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• 2004

In the course of our screening for biocontrol agent (BCA) against Streptomyces scabiei and S. turgidiscabies causing potato scab using 5,000 actinomtcete isolates, 9 antagonistic strains were selected as BCA candidates through in vitro and in vivo assay. An antagonistic strain, A020645 was highly resistant to some pesticides and antibiotics such as dazomet and mancozeb and showed high control value in vivo. Two bioactive compounds (compound A, B) were purified by anion exchange chromatography, solid phase (ODS) extraction, TLC and reverse phase HPLC. Their chemical structures are now thought to be nucleoside derivative as determined by $^1H-NMR$ data analysis. Their full chemical structures would be elucidated through $^{13}C-NMR$, HMQC and HMBC analyses. Further studies will be focused on fitness in soil and formulation of the BCA candidates.