• 한국전기전자재료학회:학술대회논문집
• /
• 한국전기전자재료학회 2010년도 하계학술대회 논문집
• /
• pp.16-16
• /
• 2010

The multilayer piezoelectric transformer was manufactured using $Pb(Zn_{1/2}W_{1/2})O_3-Pb(Mn_{1/3}Nb_{2/3})O_3-Pb(Zr_{0.48}Ti_{0.52})O_3$ (abbreviated as PZW-PMN-PZT) ceramics and their electrical properties were investigated. The $k_{eff}$ of the input and the output calculated from the resonant and anti-resonant frequencies were 0.403 and 0.233, respectively. The voltage step-up ratio showed the maximum value in the vicinity of 81kHz. The multilayer piezoelectric transformer showed the temperature rise of about $36^{\circ}C$ at the output power of 12w.

• 한국콘크리트학회:학술대회논문집
• /
• 한국콘크리트학회 1996년도 봄 학술발표회 논문집
• /
• pp.107-111
• /
• 1996

The testing specimens were made from the standard mix proportion according to those of domestic PC factories to establish a basic data for the Accelerated Curing Effect. The experimental tests were conducted according to the conditions of each sub-curing periods. By comparing the results of compression tests on de-molded and 28-day water-curing specimens, we find that the most effective curing condition to obtain more than the required design strength after 28 days of water curing may be as follwings; the presteaming period does not affect seriously and less than $30^{\circ}C$/hr-the rate of temperature rise and less than $82^{\circ}C$ - maximum temperature are necessary. It seems that post-curing procedure is very important factor to increase the effect of accelerated curing.

• 복식
• /
• 제52권3호
• /
• pp.19-27
• /
• 2002

This paper surveys the mordanting and dyeing properties of Sophora japonica L. Appropriate extraction, dyeing and mordanting condition of Sophora japonica L. were determined, and the effect of mordanting method on dye uptake and color fastness of dyed fabric was investigated. The maximum absorbance of Sophora japonica L. solution was 367.6mn, rutin solution was 365.6mn. The color of Sophora japonica L. solution was affected at pH 2 and pH 8~9. The optimum temperature to extract Sophora japonica L. was during 1 hour in 8$0^{\circ}C$. The effective dyeing temperature and time of silk were 10$0^{\circ}C$, 60min. K/S value of dyeing fabrics was increased by pre-mordanting treatment, especially Fe, Sn, Cr. In the case of Sophora japonica L. light fastness was increased by Fe mordanting. Perspiration fastness was better in acidic solution than that in alkaline solution. Fastness to rubbing and dry-cleaning were good in general.

• 한국자동차공학회논문집
• /
• 제13권5호
• /
• pp.181-187
• /
• 2005

The behavior of fox adsorption and desorption of the NOx storage catalyst supported on Ba additive were studied by the TPA/TPD experiments and reactivity tests. Applying the transient responses and NOx TPA/TPD test by CLD were effective methods to analyze the characteristics of the NOx storage catalyst. NOx variation of the NOx storage catalyst in the lean air/fuel conditions according to temperature was dominated by NOx adsorption and desorption rather than catalytic reduction. The presence of reductants in the lean mixture promoted the NOx desorption at the $500^{\circ}C$ higher temperature. The temperatures for maximum NOx conversion with CH4 and $C_3H_6$ as a rich spike reductant appear around $500^{\circ}C\;and\; 400^{\circ}C$ respectively.

• 한국분말재료학회지
• /
• 제18권5호
• /
• pp.401-405
• /
• 2011

Half-heusler phase ZrNiSn is one of the potential thermoelectric materials for high temperature application. In an attempt to investigate the effect of Sb doping on thermoelectric properties, half-heusler phase $ZrNiSn_{1-x}Sb_x$ ($0{\leq}x{\leq}0.08$) was synthesized by mechanical alloying of stoichiometric elemental powder compositions, and consolidated by vacuum hot pressing. Phase transformations during mechanical alloying and hot consolidation were investigated using XRD. Sb doped ZrNiSn was successfully produced in all doping ranges by vacuum hot pressing using as-milled powders without subsequent annealing. Thermoelectric properties as functions of temperature and Sb contents were evaluated for the hot pressed specimens. Sb doping up to x=0.04 in $ZrNiSn_{1-x}Sb_x$ was shown to be effective on thermoelectric properties and the figure of merit (ZT) was shown to reach to the maximum at x=0.02 in this study.

• JSTS:Journal of Semiconductor Technology and Science
• /
• 제13권1호
• /
• pp.65-70
• /
• 2013

A 0.18-${\mu}m$ 3.3 V grounded-gate NMOS (GGNMOS) I/O cell array for timing controller (TCON) application is proposed for improving electrical overstress (EOS) robustness. The improved cell array consists of 20 GGNMOS, 4 inserted well taps, 2 end-well taps and shallow trench isolation (STI). Technology computer-aided design (TCAD) simulation results show that the inserted well taps and extended drain contact gate spacing (DCGS) is effective in preventing EOS failure, e.g. local burnout. Thermodynamic models for device simulation enable us to obtain lattice temperature distributions inside the cells. The peak value of the maximum lattice temperature in the improved GGNMOS cell array is lower than that in a conventional GGNMOS cell array. The inserted well taps also improve the uniformity of turn-on of GGNMOS cells. EOS test results show the validity of the simulation results on improvement of EOS robustness of the new GGNMOS I/O cell array.

• 한국세라믹학회지
• /
• 제48권3호
• /
• pp.251-256
• /
• 2011

The luminescence properties of polycrystalline ZnO annealed in reducing ambience ($H_2/N_2$) have been studied. An effective quenching of green luminescence with enhanced UV emission from polycrystalline ZnO is observed for the reduced ZnO. The variations of the UV and green luminescence band upon reduction treatment are investigated as a function of temperature in the range between 20 and 300 K. Upon annealing treatment in reducing ambience, the optical quality of polycrystalline ZnO is improved. The UV to green intensity ratio of sintered ZnO approaches close to zero (~0.05). However, this ratio reaches more than 13 at room temperature for polycrystalline ZnO annealed at $800^{\circ}C$ in reducing ambience. Furthermore, the full width at half maximum (FWHM) of the UV band of polycrystalline ZnO is reduced compared to unannealed polycrystalline ZnO. Electron paramagnetic resonance (EPR) measurements clearly show that there is no direct correlation between the green luminescence and oxygen vacancy concentration for reduced polycrystalline ZnO.

• Journal of Microbiology and Biotechnology
• /
• 제15권2호
• /
• pp.412-420
• /
• 2005

In order to investigate factors affecting the denitrification in the F-STEP PROCESS using a loess ball as support media and Pseudomonas DWC 17-8, calcining temperature, loess ball size, pH, nitrate concentration, working temperature, and inhibitor were studied in batch mode using synthetic sludge. A 5- 10 mm of loess ball (960$^{circ}$ of calcining temperature) was the most suitable for denitrification. When the initial pH was increased from 3.0 to 7.0, the removal efficiency of nitrate was increased. Specifically, at initial pH of 7.0, the maximum removal efficiency of nitrate was 5.0 mg/min. When the initial concentration of nitrate was increased from 100 to 400 mg/l, the removal efficiency of nitrate was proportional to the concentration of nitrate. The maximum removal efficiency of nitrate was 5.72 mg/min at 400 mg/l of initial concentration. When the operating temperature was increased from 10 to 30$^{circ}$, the removal efficiency of nitrate was increased from 0.76 to 6.15 mg/min, and at above 40$^{circ}$ of operating temperature, it was decreased from 4.0 to 2.0 mg/min. Among the various inhibitors, higher than 10$^{-1}$ M of sodium azide abolished this reaction completely. When the KCN concentration was above 10$^{-1}$ M, the reaction was inhibited completely. In the case of 2,4-dinitrophenol and sodium sulphide, it was inhibited at above 10$^{-2}$ M completely. For testing the various flow orders of the F-STEP PROCESS for effective denitrification using practical wastewater, continuous experiments under the optimum conditions were carried out for 60 days. Among the various processes, the PROCESS A gave the highest efficiencies of denitrification, nitrification, and total nitrogen (TN) removal with 86.5, 89.5, and $90\%$, respectively. For scale-up in the PROCESS A, real farm wastewater was used and pilot tests carried out for 90 days. The denitrification efficiency was $97.5\%$, which was increased by $12.7\%$. The efficiencies of TN removal and nitrification were 96.6 and $70.0\%$, respectively. The removal efficiency of chemical oxygen demand (COD) was $63.7\%$, which was increased by $20\%$.

• 설비공학논문집
• /
• 제24권1호
• /
• pp.51-60
• /
• 2012

Optimization procedures of performance analysis for ORC(Organic Rankine Cycle) system are established to the characteristics of low temperature heat sources such as open-type and closed-type. Effective heat recovery and heat extraction related to maximum power of the cycle as well as heat quality and thermal efficiency must be considered in the case of the open-type low temperature heat source. On the other hand, in the case of the closed-type low temperature heat source, only thermal efficiency is important due to constant heat input. In this study, thermal efficiency and exergy efficiency representing a level of close to Carnot cycle are studied, as useful index for the optimization of the ORC system. To validate the results of cycle analysis, those are compared with appropriate experimental data of ORC system as a thermal efficiency point of view.

• 한국태양에너지학회:학술대회논문집
• /
• 한국태양에너지학회 2011년도 춘계학술발표대회 논문집
• /
• pp.68-73
• /
• 2011

An experimental study was conducted to investigate the thermal performance of a medium-temperature heat pipe against the charge amount of working fluid. The container and the wick of the heat pipe were made of stainless steel and the working fluid was Dowtherm-A for medium-temperature applications around $250^{\circ}C$. The diameter and length of the heat pipe were 25.4 mm and 1 m, respectively. The maximum thermal load was 1 kW and the working fluid charge ratio varied from 372% to 420%. The results showed that the thermal resistance ranged from 0.12 to $250^{\circ}C/W$ and the effective thermal conductance ranged from 7,703 to $8,898 W/m{\cdot}K$. Dry-out occurred for the heat pipe with 372% fill-charge at the heat load of 950 W, while the other heat pipes with higher charge amount did not encounter dry-out up to 1060 W.