• 한국정보디스플레이학회:학술대회논문집
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• 2007.08b
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• pp.1497-1499
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• 2007

Visual perception experiments were conducted to determine the acceptable limit of the contrast ratio of LCD TV under the watching condition. The results showed that the corresponding contrast ratio should be below 10,000:1 at the 3H(height of screen) distance in the living room environment.

• Journal of environmental and Sanitary engineering
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• v.16 no.2
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• pp.32-37
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• 2001

The purpose of this study was to investigate the created liquid post-acid fermentation of usability of denitrification as exterior carbon sources by pH control. The time of acid fermentation of food waste, the slower loading capacity of organic matter, the faster decomposition rate, but the density of generation Volatile Fermentation Acids(VFAs), was weak and, $SBOD_{5}$ : ST-N rate and $SBOD_{5}/SCOD_{Cr}$ rate was low. Between TS and VS, VS was decreased to 4.5th day fast, and then was decreased slowly. 1.5 days after stating the experiments, $SCOD_{Cr}$, $SBOD_{5}$, STOC and $VFA_{s}$ was decreased of increased slowly, and then increased fast. And after showing the highest density, it was tended to decreased fast. At the time of $SBOD_{5}$ with the highest density, at $SBOD_{5}$ : ST-N ratio, $R_1$ was 303:1, $R_2$ was 319:1, $R_3$was the highest. After studying $SBOD_{5}$ : ST-N ratio and $SBOD_{5}/SCOD_{Cr}$ ratio, as a carbon source of biological denitrification it was profitable composition ratio.

• Bulletin of the Korean Chemical Society
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• v.28 no.8
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• pp.1317-1321
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• 2007

Arginine conjugated PAMAM dendrimer, PAMAM-R was modified with propylene oxide via hydroxylation of primary amines of arginine residues. About 49 amines were detected to be converted to amino alcohols by 1H NMR. The newly synthesized polymer, PAMAM-R-PO was able to completely retard pDNA from a charge ratio of 2. The average diameter of PAMAM-R-PO polyplex was found to be 242 nm at a charge ratio of 30. The Zeta-potential value of PAMAM-R-PO polyplex was able to reach 20-30 mV over a charge ratio of 10. PAMAM-R-PO indicated higher cell viability than unmodified PAMAM-R on HeLa and 293 cells because of its hydroxylated amines. Transfection experiments on 293 cells showed that the transfection efficiency of PAMAM-R-PO was found to be 1.5-1.9 times higher than that of PEI25kDa at a charge ratio of 30. The polymer eventually displayed about 2 times greater transfection efficiency than PAMAM-R at the same charge ratio in the absence of serum. Therefore, we concluded that the modification of primary amines of PAMAMR to amino alcohols gives positive effects such as reduced cytotoxicity and enhanced transfection efficiency on 293 cells for gene delivery potency of PAMAM-R.

• Korean Journal of Materials Research
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• v.3 no.6
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• pp.661-667
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• 1993

Effects of $SiH_4//WF_6$(=R) ratio on the electrical properties of W films such as resistvity, contact resistance, junction leakage current in the selective W CVD technology for contact barrier metal were investigated with the emphasis on the role of $\alpha$-W Resistivity of W increases with increasing R, which is primarily due to the phase transformation from $\alpha$-W to , $\alpha$-W. $\alpha$-W found in the SiH4 reduced CVD W film is stabilized by Si incorporated into the W film rather than by oxygen. $\alpha$-W is found in the W film deposited on the Si substrate for high R, while $\alpha$-W is not found in the W film deposited on the TiN substrate even for high R. Also junction leakages increase with increasing R, which is caused not only by the vertical Si consumption but also the lateral Si consumption.

• The Journal of the Acoustical Society of Korea
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• v.42 no.4
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• pp.298-303
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• 2023

This study aimed to investigate the clinical utility of voiced sentence tasks for voice evaluation. To this end, we analyzed the correlation between perturbation-based acoustic measurements [jitter percent (jitter), shimmer percent (shimmer), Noise to Harmonic Ratio (NHR)] using sustained vowel phonation, and cepstrum-based acoustic measurements [Cepstral Peak Prominence (CPP), Low/High spectral ratio (L/H ratio)] using voiced sentences. As a result of analyzing data collected from 65 patients with voice disorders, there was a significant correlation between the CPP and jitter (r = -.624, p = .000), shimmer (r = -.530, p = .000), NHR (r = -.469, p = .000).This suggests that the cepstrum measurement of voiced sentences can be used as an alternative to the analysis limitations of the pathological voice such as not possible perturbation-based acoustic measurement, and result difference according to the analysis section.

• The Journal of Engineering Geology
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• v.15 no.3
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• pp.337-348
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• 2005

Jurassic granite from Pocheon area were tested to investigate the effect of microcracks on mechanical properties of the granite. Three oriented core specimens were used for uniaxial compressive tests and each core specimen are perpendicular to the axes'R'(rift plane),'c'(grain plane) and'H'(hardway plane), respectively Among vacious elastic constants, the variation of Poisson's ratio as function of the directions was examined. From the related chart between ratio of failure strength and Poisson's ratio, H-specimen shows the highest range in Poisson's ratio and Poisson's ratio decreases in the order of C-specimen and R-specimen. The curve pattern is nearly linear in stage $I\simIII$ but the slope increases abruptly in stage H-3. As shown in the related chart, diverging point of a curve is formed when ratio of failure strength is $0.92\sim0.96$ Stage IV -3 is out of elastic region. The behaviour of rock in the four fracturing stages was analyzed in term of the stress-volumetric strain me. From the stress increment-volumetric strain equations governing the behaviour of rock, characteristic material constants, a, n, Q, m and $\varepsilon_v^{mcf}$, were determined. Among these, inherent microcrack porosity$(a, 10^{-3})$ and compaction exponent(n) in the microcrack closure region(stage I ) show an order of $a^R(3.82)>a^G(3.38)>a^H(2.32)\;and\;n^R(3.69)>n^G(2.79)>n^H(1.99)4, respectively. Especially, critical volumetric microcrack strain($\varepsilon_v^{mcf}$) in the stage W is highest in the H-specimen, normal to the hardway plane. These results indicate a strong correlation between two major sets of microcracks and mechanical properties such as Poisson's ratio and material constants. Correlation of strength anisotropy with microcrack orientation can have important application in rock fracture studies.

• Proceedings of the Korea Concrete Institute Conference
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• 2001.11a
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• pp.903-906
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• 2001

The objective of this experimental study was to understand the effect of horizontal shear bar on the shear behavior of R.C. deep beams. Therefore, in the test program, the horizontal shear bar ratio($\rho_{sh}$) and shear span-to-overall depth ratio(a/h) are considered as two main variables. Test results indicate that for deep beams with a/h equal to 1.0, horizontal shear bar is less efficient in restricting the diagonal crack width development and enhancing the ultimate shear strength. So, it can be concluded that shear resistance of horizontal shear bar is related to a/h rather than clear span-to-effective depth ratio($l_{n}$/d) recommended in ACI code.

• Journal of the Korean Society of Combustion
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• v.22 no.4
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• pp.51-56
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• 2017

The decomposition of tetrafluoromethane has been investigated with the reaction mechanism proposed for freely propagating $CH_4/CF_4/O_2/N_2$ premixed flames on the oxygen enrichment. The factors affecting on the removal efficiency of tetrafluoromethane were analyzed. The increase in flame temperature due to oxygen enrichment has a great influence on the removal efficiency of tetrafluoromethane. At the same oxygen enrichment condition, the removal efficiency in the rich flame is higher than one in the lean flame. The increase of the F/H ratio leads to decrease the flame temperature and the removal efficiency of tetrafluoromethan is decreased at the flame temperature of 2600 K or lower, The elementary reactions that dominate the consumption of tetrafluoromethane are (R1) $CF_4+M=CF_3+F+M$ and (R2) $CF_4+H=CF_3+HF$. (R1) has the greatest effect on the consumption of tetrafluoromethane under the oxygen enhanced flames.

• Applied Chemistry for Engineering
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• v.10 no.3
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• pp.400-406
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• 1999

In an effort to obtain high efficiency in gas fired absorption chillers, a new working fluid has been developed with thc addition of the component of $LiNO_3$, LiCl and LiI to the conventional solution of $LiBr-H_2O$. The solubility and vapor pressure of the 4 component working fluid developed in this work were measured and compared to the results of $LiBr-H_2O$ solution. It was observed that there exists an optimal mole ratio of the inorganic salts in terms of solubility. The mole ratio of LiBr, $LiNO_3$ and LiCl was found to be around 5:1:1~2 in the $LiBr-LiNO_3-LiCl-H_2O$ mixture, and in the case of $LiBr-LiO_3-Lil-H_2O$ and $LiBr-Lil-LiCl-H_2O$ mixtures, the mole ratio of LiBr, $LiNO_3$ and Lil/ LiBr, LiI and LiCl were found to be around 5:1:1 and 5:1:0.5~1 respectively. The vapor pressure of the 4 component working fluid of the optimal mole ratio was increascd with adding the component of $LiNO_3$, LiCl and LiI except for $LiBr-LiNO_3-LiCl-H_2O$ mixture. The absorption capacity of $LiBr-LiNO_3-LiCl-H_2O$ mixture was obtained higher than that of $LiBr-H_2O$ mixture.

• 한국정보디스플레이학회:학술대회논문집
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• 2004.08a
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• pp.799-802
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• 2004

In this paper, the active backlight control technology with data processing algorithm was developed in order to improve image quality for IPS-mode LCD-TV applications. The image blinking problem caused by repeatedly abrupt change of the backlight luminance was solved by algorithms-Fba(Flexible Boundary algorithm) and Cfa(Cumulative Feedback algorithm)-and the optimized number and space of backlight dimming steps based on perception. In the IPS-mode 42" TFT-LCD panel, the dynamic contrast ratio can be more than twice the typical level by means of lower block luminance and higher white luminance. Additionally, Power consumption and LCD temperature was decreased.