• 한국재료학회지
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• 제23권8호
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• pp.435-440
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• 2013

Transparent and conducting thin films of Ta-doped $SnO_2$ were fabricated on a glass substrate by a pulse laser deposition(PLD) method. The structural, optical, and electrical properties of these films were investigated as a function of doping level, oxygen partial pressure, substrate temperature, and film thickness. XRD results revealed that all the deposited films were polycrystalline and the intensity of the (211) plane of $SnO_2$ decreased with an increase of Ta content. However, the orientation of the films changed from (211) to (110) with an increase in oxygen partial pressure (40 to 100 mTorr) and substrate temperature. The crystallinity of the films also increased with the substrate temperature. The electrical resistivity measurements showed that the resistivity of the films decreased with an increase in Ta doping, which exhibited the lowest resistivity (${\rho}{\sim}1.1{\times}10^{-3}{\Omega}{\cdot}cm$) for 10 wt% Ta-doped $SnO_2$ film, and then increased further. However, the resistivity continuously decreased with the oxygen partial pressure and substrate temperature. The optical bandgap of the 10 wt% Ta-doped $SnO_2$ film increased (3.67 to 3.78 eV) with an increase in film thickness from 100-700 nm, and the figure of merit revealed an increasing trend with the film thickness.

• 한국수소및신에너지학회논문집
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• 제29권4호
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• pp.401-409
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• 2018

A numerical investigation has been conducted to find the effects of pressure losses by struts and rakes, and averaging methods on the performance of a multi-stage axial fan and a multi-stage axial compressor. Struts and rakes which produce pressure losses are installed upstream of the aerodynamic inlet plane in the fan and the compressor rigs. Some of normal stator vanes are substituted with thick vanes with total pressure probes to measure total pressure between stages. Three-dimensional Reynolds-averaged Navier- Stokes equations with $k-{\omega}$ SST turbulence model were applied to analyze the pressure losses by the struts, inlet rakes, and thick instrumented vanes. The hexahedral grids were used to construct computational domain. Inlet pressure losses were evaluated for the compressor as a function of Mach number. The passage pressure losses due to the instrumented vanes were evaluated at the two speed lines in the fan. Total properties, such as pressure and temperature, were evaluated at the exit of the fan and the compressor with two different averaging methods which are area-averaging and mass-averaging, respectively.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2010년도 하계학술대회 논문집
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• pp.388-388
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• 2010

In this study, Ferroelectric vinylidene fluoride-trifluoroethylene (VF2-TrFE) copolymer films were directly deposited on degenerated Si (n+, $0.002\;{\Omega}{\cdot}cm$) using by spin coating method. A 1~5 wt% diluted solution of purified vinylidene fluoride-trifluoroethylene (VF2:TrFE = 70:30) in a dimethylformamide (DMF) solvent were prepared and deposited on silicon wafers at a spin rate of 2000 ~ 4000 rpm for 2 ~ 30 seconds. After annealing in a vacuum ambient at 100 ~ $200^{\circ}C$ for 60 min, upper aluminum electrodes were deposited by vacuum evaporation for electrical measurement. X-ray diffraction results showed that the VF2-TrFE films on Si substrates had $\beta$-phase of copolymer structures. The capacitance on highly doped Si wafer showed hysteresis behavior like a butterfly shape and this result indicates clearly that the copolymer films have ferroelectric properties. The typical measured remnant polarization ($P_r$) and coercive filed ($E_c$) values were about $5.7\;{\mu}C/cm^2$ and 710 kV/em, respectively, in an applied electric field of ${\pm}$ 1.5 MV/em. The gate leakage current densities measured at room temperature was less than $7{\times}10^{-7}\; A/cm^2$ under a field of 1 MV/cm.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2010년도 하계학술대회 논문집
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• pp.244-244
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• 2010

Doping process of crystalline silicon solar cell process is very important which is as influential on efficiency of solar. Doping process consists of pre -deposition and diffusion. Each of these processes is important in the process temperature and process time. Through these process conditions variable, p-n junction depth can be controled to low and high. In this paper, we studied a optimized doping pre-deposition temperature for high solar cell efficiency. Using a $200{\mu}m$ thickness multi-crystalline silicon wafer, fixed conditions are texture condition, sheet resistance($50\;{\Omega}/sq$), ARC thickness(80nm), metal formation condition and edge isolation condition. The three variable conditions of pre-deposition temperature are $790^{\circ}C$, $805^{\circ}C$ and $820^{\circ}C$. In the $790^{\circ}C$ pre-deposition temperature, we achieved a best solar cell efficiency of 16.2%. Through this experiment result, we find a high efficiency condition in a low pre-deposition temperature than the high pre-deposition temperature. We optimized a pre-deposition temperature for high solar cell efficiency.

• 한국전기전자재료학회논문지
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• 제24권11호
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• pp.882-889
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• 2011

In this study, we have investigated the effects of Co doping on I-V curves, bulk trap levels and grain boundary characteristics of ZnO-$Bi_2O_3$ (ZB) varistor. From I-V characteristics the nonlinear coefficient (a) and the grain boundary resistivity (${\rho}_{gb}$) decreased as 32${\rightarrow}$22 and 18.4${\rightarrow}0.6{\times}10^9{\Omega}cm$ with sintering temperature (900~1,300$^{\circ}C$), respectively. Admittance spectra and dielectric functions show two bulk traps of zinc interstitial, $Zn_i^{{\cdot}{\cdot}}$(0.16~0.18 eV) and oxygen vacancy, $V_o^{{\cdot}}$ (0.28~0.33 eV). The barrier of grain boundaries in ZBCo (ZnO-$Bi_2O_3-Co_3O_4$) could be electrochemically single type. However, its thermal stability was slightly disturbed by ambient oxygen because the apparent activation energy of grain boundaries was changed from 0.93 eV at the 460~580 K to 1.13 eV at the 620~700 K. It is revealed that Co dopant in ZB reduced the heterogeneity of the barrier in grain boundaries and stabilized the barrier against the ambient temperature.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2008년도 추계학술대회 논문집 Vol.21
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• pp.20-21
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• 2008

Ferroelectric vinylidene fluoride-trifluoroethylene ($VF_2$-TrFE) copolymer films were directly deposited on degenerated Si ($n^+$, 0.002 $\Omega{\cdot}cm$) using by dip coating method. A 1 ~ 3 wt% diluted solution of purified vinylidene fluoride-trifluoroethylene ($VF_2$:TrFE=70:30) in a dimethylformamide (DMF) solvent were prepared and deposited on silicon wafers using dip coating method for 10 seconds. After Post-Annealing in a vacuum ambient at 100~200 $^{\circ}C$ for 60 min, upper aluminum electrodes were deposited by thermal evaporation through the shadow mask to complete the MFS structure. The ferroelectric $\beta$-phase peak of films, depending on the annealing temperature, started to show up around $125^{\circ}C$, and the intensity of the peak increased with increasing annealing temperature. Above $175^{\circ}C$, the peak started to decrease. The C-V characteristics were measured using a Precision LCR meter (HP 4284A) with frequency of 1MHz and a signal amplitude of 20 mV. The leakage-current versus electric-field characteristics was measured by mean of a pA meter/DC voltage source (HP 4140B).

• 한국축산식품학회지
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• 제35권3호
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• pp.330-338
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• 2015

The effects of dietary supplementation of processed sulfur in pigs according to the level provided during the fattening phase were examined. The pigs were divided into three groups: control (CON), non-sulfur fed pigs; T1, 0.1% processed sulfur fed pigs; T2, 0.3% processed sulfur fed pigs. Physicochemical and sensory properties, as well as meat quality and oxidative stability of the Longissimus dorsi muscle were investigated. The feeding of processed sulfur did not affect moisture and protein contents (p>0.05). However, the crude fat content of T2 was significantly decreased compared to CON (p<0.05), while the pH value of T2 was significantly higher than those of both CON and T1 (p<0.05). Cooking loss and expressible drip of T2 were also significantly lower than that of CON (p<0.05). The redness of meat from T1 was significantly higher than both CON and T2 (p<0.01). During storage, lipid oxidation of the meat from sulfur fed pigs (T1 and T2) was inhibited compared to CON. Examination of omega-3 polyunsaturated fatty acids revealed T2 to have significantly higher content than CON (p<0.05). In the sensory test, the juiciness and overall acceptability of T2 recorded higher scores than CON. This study demonstrated that meat from 0.3% processed sulfur fed pigs had improved nutrition and quality, with extended shelf-life.

• Journal of Magnetics
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• 제9권2호
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• pp.52-59
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• 2004

As deposited and annealed MTJs with the structure of $Ta(5 nm)/Cu(10 nm)/Ta(5 nm)/Ni_{80}Fe_{20}(2 nm)/Cu(5 nm)/ Ir_{25}Mn_{75}(10 nm)/Co_{70}Fe_{30}(2.5 nm)/Al-O/Co_{70}Fe_{30}(2.5nm)/Ni_{80}Fe_{20}(t)/Ta(5nm)/Ni_{80}Fe_{20}(t)/Ta(5 nm)$, where t=10, 30, 60 and 100 nm were characterized by XRD and magnetic hysteresis loops measurements. The XRD measurements were done in grazing incidence $(GID scan-2{\theta})$ and ${\theta}-2{\theta}$ geometry, by rocking curve $(scan-{\omega})$ and pole figures in order to establish correlation between texture and crystallites size and magnetic parameters of exchange biased and interlayer coupling. The variations of shifting and coercivity field of free and pinned layers after annealing in $300^{\circ}C$ correlate with the improvement of ［111］ texture and grains size of $Ni_{80}Fe_{20}$ and $Ir_{25}Mn_{75}$ respectively. The exchange biased and the coercivity fields of the pinned layer linearly increased with increasing grain size of $Ir_{25}Mn_{75}$, The reciprocal proportionality between interlayer coupling and coercivity fields of the free layer and grain size of $Ni_{80}Fe_{20}$ was found. The enhancement of interlayer coupling between pinned and free layers, after annealing treatment, indicates on the correlated in-phase roughness of dipolar interacting interfaces due to increase of crystallites size of $Ni_{80}Fe_{20}$.

• 대한한방부인과학회지
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• 제23권1호
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• pp.83-96
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• 2010

Purpose: A survey was conducted by questionnaire to investigate outpatients' intake status of health food. Methods: The survey of visiting oriental OB&GY clinic in 4 hospitals of oriental medicine and 1 oriental medical clinic has found the status of health food intake. Results: 1. Total respondents were 339(Male: 54, Female: 264) and their average age was $41.4{\pm}11.8$. Outpatients of oriental medicine clinic were 113, outpatients of hospitals of oriental medicine were 226. 2. Among the respondents, 156(40%) persons were taking health food as of today and the proportion of health food intake by oriental medicine clinic's outpatients is higher than the proportion of outpatients of hospitals of oriental medicine. 3. There is no difference in educational background and income among the outpatients who visited the oriental medicine clinic or hospitals of oriental medicine. And the middle income group's health food intake ratio was the highest. 4. The survey showed that heath food intake ratio got higher as persons became old. 5. Among the health foods, the multi-vitamin was most frequently taken. And omega 3, Ginseng steamed red, Vitamin C, Glucosamine, Calcium m were also frequently taken. Conclusion: A study for health food intake status by clinic is indispensable to establish the standard for efficient intake of health food.

• 센서학회지
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• 제13권2호
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• pp.128-132
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• 2004

Short wave infrared (SWIR) photovoltaic devices have been fabricated from metal organic vapour phase epitaxy (MOVPE) grown n- on p- HgCdTe films on GaAs substrates. The MOVPE grown films were processed into mesa type discrete devices with wet chemical etching employed for meas delineation and ZnS surface passivatlon. ZnS was thermally evaporated from effusion cell in an ultra high vacuum (UHV) chamber. The main features of the ZnS deposited from effusion cell in UHV chamber are low fixed surface charge density, and small hysteresis. It was found that a negative flat band voltage with -0.6 V has been obtained for Metal Insulator Semiconductor (MIS) capacitor which was evaporated at $910^{\circ}C$ for 90 min. Current-Voltage (I-V) and temperature dependence of the I-V characteristics were measured in the temperature range 80 - 300 K. The Zero bias dynamic resistance-area product ($R_{0}A$) was about $7500{\Omega}-cm^{2}$ at room temperature. The physical mechanisms that dominate dark current properties in the HgCdTe photodiodes are examined by the dependence of the $R_{0}A$ product upon reciprocal temperature. From theoretical considerations and known current expressions for thermal and tunnelling process, the device is shown to be diffusion limited up to 180 K and g-r limited at temperature below this.