• Bulletin of the Korean Chemical Society
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• v.33 no.7
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• pp.2309-2314
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• 2012

Ag deposited N-$TiO_2$ composite nanoparticles were prepared via $NH_3$ plasma treatment. X-ray diffraction, UV-vis spectroscopy, photoluminescence, and X-ray photoelectron spectroscopy were used to characterize the prepared $TiO_2$ samples. The plasma treatment did not change the phase composition and particle sizes of $TiO_2$ samples, but extended its absorption edges to the visible light region. The photocatalytic activities were tested in the degradation of an aqueous solution of a reactive dyestuff, methylene blue, under visible light. The photocatalytic activities of Ag deposited N-$TiO_2$ composite nanoparticles were much higher than Ag-$TiO_2$, N-$TiO_2$, and P25. A possible mechanism for the photocatalysis was proposed.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.11a
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• pp.135-136
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• 2008

이 실험에서는 비휘발성 메모리에서의 블로킹 층으로 $SiN_x$ 박막을 사용하였다. ELA (poly-Si) 기판위에 $SiO_xN_y$ 박막을 성장하기 전에 BHF를 이용해 자연 산화막을 제거하였다. 터널 층을 위해 2.7nm두께의 $SiO_xN_y$를 ICP-CVD 장비를 이용해 유리기판위에 증착하였다. 다음으로 $SiH_4/H_2$기체를 이용， ICP-CVD장비를 이용해 전하 저장을 위한 a-Si 박막을 증착하고, 마지막으로 a-Si층 위에 $SiN_x$ 층을 형성하였다. $SiN_x$ 박막을 형성하는데 최적의 조건을 찾기 위해 가스의 구성 비율 및 증착시간을 변화시키고 온도와 RF power도 바꿔주었다. 굴절률이 1.79 고 두께가 30 nm 인 $SiN_x$는 블로킹 층으로 사용하기 위한 것이다. 제작된 NSO-NVM 소자의 전기적 메모리 특성은 on current가 약 $10^{-5}$ A 이고 off current가 약 $5\times10^{-13}$ A로 전류 점멸비$(I_{ON}/I_{OFF})$는 약 $1\times10^7$ 이고 Swing 값은 0.53V/decade 이다. 1ms 동안의 programming/erasing 결과 약 3.5 V의 넓은 메모리 윈도우 크기를 가진다는 것을 확인할 수 있다.

• Journal of the Korean Ceramic Society
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• v.25 no.2
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• pp.143-153
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• 1988

In order to synthesize the partially stabilized $\alpha$-Sialon, A1N and Y2O3 were added to synthesized $\alpha$-Si3N4. The phase composition, mechanical properties, micro structure, etc, of the synthesized $\alpha$-Sialon were investigated. Partially stabilized $\alpha$-Sialon ceramics could be synthesized from the composition which was a little deviated from x=0.4, x=0.6 composition along the Si3N4.0.1Y2O3:0.9AlN tie line at 1750-180$0^{\circ}C$ for 2 hrs in N2 atmosphere. It is assumed that A1N is more closely related than Y2O3 to the formation of $\alpha$-Sialon, and that A1N is more easily dissolved into $\alpha$-structure than into $\beta$-structure. In Ya2O3-rich phase mechanical properties were observed to be poor because of formation of mellilite, grain growth, and thermal decomposition of $\alpha$-Sialon. The maximum values of M.O.R, KIC and hardness are 723 MPa, 4.5MN/㎥/2 and 19.3 GPa, respectively, and they were observed for the $\alpha$-Sialon ceramics sintered at 178$0^{\circ}C$.

• Journal of the Korean Ceramic Society
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• v.40 no.11
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• pp.1058-1061
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• 2003

Gallium Nitride (GaN) powders were synthesized by calcining a gallium(III) sulfate salt in flowing ammonia in the temperature range 500-1100$^{\circ}C$. The process of conversion of the salt to GaN was monitored by X-Ray Diffraction (XRD). The salt decomposed to ${\gamma}$-Ga$_2$O$_3$ and then converted to GaN without ${\gamma}$-${\beta}$Ga$_2$O$_3$ phase transition. Variations in XRD patterns and weight loss of samples with temperature indicate that the conversion of ${\gamma}$-Ga$_2$O$_3$ to GaN does not proceed through Ga$_2$O but stepwise via amorphous gallium oxynitride (GaO$\_$x/N$\_$y/) as intermediates. Room-temperature photoluminescence spectra of GaN powders obtained showed the emission peak at 363 nm and no yellow band.

• Bulletin of the Korean Chemical Society
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• v.33 no.4
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• pp.1303-1309
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• 2012

A novel ligand N,N'-(2,6-pyridinedicarbonyl)bis[N-(carboxymethyl)] (L1) was designed and synthesized. Four co-luminescence groups of Sm-La-pyridyl carboxylic acids systems were researched, which are $K_4Sm_{(1-x)}-La_x(L_1)Cl_3{\cdot}y_1H_2O$, $K_4Sm_{(1-x)}La_x(L_2)Cl_3{\cdot}y_2H_2O$, $K_6Sm_{2(1-x)}La_{2x}(L_3)Cl_6{\cdot}y_3H_2O$, $K_4Sm_{(1-x)}La_x(L_4)Cl_3{\cdot}y_4H_2O$. The results indicated the addition of La(III) could sensitize the luminescence of Sm(III) obviously in a certain range, enhancing emission intensity of Sm-pyridyl carboxylic acids relative to the undoped ones. The optimal mole percentages of La(III) in the mixed ions for $L_1$, $L_2$, $L_3$, $L_4$ were confirmed to be 0.6, 0.5, 0.3, 0.6, respectively. The mechanism of the fluorescence enhancement effect was discussed in detail. Furthermore, the binding interaction of $K_4Sm_{0.4}La_{0.6}(L_4)Cl_3{\cdot}5H_2O$ with bovine serum albumin (BSA) have been investigated due to its potential biological activity. The binding site number n was equal to 1.0 and binding constant $K_a$ was about $2.5{\times}10^5\;L{\cdot}mol^{-1}$.

• Korean Journal of Environment and Ecology
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• v.12 no.2
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• pp.131-137
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• 1998

This study was performed to investigate tree injury with air pollution and acid precipitation in industrial area and rural area. This study analyzed the ion properties of pollutant precipitated in the forest of Ulsan ＆ Onsan area and correlation between S $O_2$concentration in air and the degree of forest decline. pH of industrial area was lower than that of rural area and electrical conductivity and pH had a negative correlation(r=-.7861$^{**}$). Correlation of cation and anion(especially S $O_{4}$$^{2-}$, N $O_{3}$$^{[-10]}$ ) in precipitation and S $O_2$in air was higher in industrial area. In seasonal change, winter and spring were higher. In the analysis of correlation between forest decline and variables of precipitation properties, correlation coefficient was higher by following order: S $O_{4}$$^{2-}$>pH>EC>N $O_{3}$$^{[-10]}$ >S $O_{2}$$^{2-}$>C $l^{[-10]}$ . Regression formula by computation was Y = 5.1007-0.7811 $X_2$(pH) +0.0253 $X_{5}$ (S $O_{4}$$^{2-}$) +0.0275 $X_{6}$ (N $O_{3}$$^{[-10]}$ ). In considering the result of this study, it was predicted that air pollution and acid rain would affect soil acidification and forest decline continuously.y.

• Journal of Korean Ophthalmic Optics Society
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• v.5 no.1
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• pp.7-11
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• 2000

The anti-reflective anti-static (ARAS) optical film is designed using absorbent materials such as ITO, $TiN_xW_y$, Ag by Essential Macleod program. [air ${\mid}TiN_xW_y{\mid}SiO_2{\mid}$ glass] two layer shows wide-band AR coating in the wavelength range of 450~700 nm. The reflectivity, transmittance of this coating are below 0.5%, about 75%, respectively. [air $SiO_2{\mid}TiO_2{\mid}SiO_2{\mid}$, ITO glass] layer can adjust reflectance of below 0.5% with above 97% transmittance. In the [air ${\mid}SiO_2{\mid}TiO_2{\mid}SiO_2{\mid}$ Ag glass] layer, the transmission can be controlled at above 96% with reflectance of 1~2%.

• Journal of Sensor Science and Technology
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• v.1 no.1
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• pp.5-12
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• 1992

We have fabricated a-Si:H multilayer for contact-type linear image sensor by means of RF glow discharge decomposition method. The ITO/i-a-Si:H/Al structure has relatively high dark current due to indium diffusion and carrier injection from both electrodes, resulting in low photocurrent to dark current. To suppress the dark current and to enhance interface electric field between ITO and i-a-Si:H film we have fabricated ITO/insulator/i-a-S:H/p-a-S:H/Al multilayer film with blocking structure. The photocurrent of ITO/$SiO_{2}(300{\AA})$/i-a-Si:H/p-a-Si:H($1500{\AA}$)/Al multilayer sensor with 5V bias voltage became saturated at about 20nA under $20{\mu}W/cm^{2}$ light intensity, while the dark current was less than 0.1nA. To increase the light generation efficiency we have adopted ITO/$SiO_{x}N_{y}(300{\AA})$/i-a-Si:H/p-a-Si:H($1500{\AA}$)/Al structure, showing photocurrent of 30nA and dark current of 0.08nA with 5V bias voltage. Also the spectral photosensitivity of the multilayer was enhanced for short wavelength visible region of 560nm, compared with that of the a-Si:H monolayer of 630nm. And its photoresponse time was about 0.3msec with the film homogeneity of 5% deviation.

• Applied Chemistry for Engineering
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• v.17 no.5
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• pp.471-475
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• 2006

$VO_x$ thin films with the thickness of 450 nm were prepared on a $Pt/Ti/SiO_{2}/Si$ substrate at room temperature by a reactive radio frequency (rf) magnetron sputtering method. The deposition rates of $VO_x$ thin films were investigated as a function of $O_{2}$ concentration and rf power. As the $O_{2}$ concentration in a $O_{2}/Ar$ mixture increased, the deposition rate decreased. However, the deposition rate increased with increasing rf power. The deposited $VO_x$ thin films were annealed at $450^{\circ}C$ for 2, 4, and 6 h in $O_{2}$ and $N_{2}$ ambient. After annealing, the phase changes of $VO_x$ thin films were investigated using X-ray diffraction analysis. The plane and cross-sectional views of $VO_x$ thin films before and after annealing were observed by field emission scanning electron microscopy. The metal-insulator transition (MIT) properties of $VO_x$ thin films were measured using current-voltage measurement. The excellent MIT properties were observed in $VO_x$ thin films annealed in $O_{2}$ ambient.

• Journal of the Korean Electrochemical Society
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• v.6 no.4
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• pp.266-270
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• 2003

The $LiN_{0.8}Co_{0.2}O_2$ has shown outstanding electrochemical properties. The microstructure of $LiN_{0.8}Co_{0.2}O_2$ cathode was investigated by using TEM (transmission electron microscopy) and X-ray diffraction techniques. The $LiN_{0.8}Co_{0.2}O_2$ was produced by sol-gel method to synthesize fine particles less than $1{\mu}m$ in the average diameter. In this study, emphasis was given to the examination and interpretation of the microstructural change during charge-discharge cycling experiments, which appeared to be one of the main causes of early degradation of rechargeable batteries. Results showed that the $1{\mu}m$ cathode produced by sol-gel method had high reversible capacity and excellent cycling stability due to its homogeneous distribution of Ni and Co cations on u atomic scale. In particular, the $1{\mu}m$ cathode did not show severe strain induced structural defects or cubic spinel disordering during cycling experiments, which had been observed in the conventional $LiCoO_2$ cathode. The $LiNi_{0.8}Co_{0.2-x}M_x[M=Al]$ compounds show good reversibility but low discharge capacity.