• Journal of applied mathematics & informatics
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• v.27 no.1_2
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• pp.205-215
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• 2009

Sufficient conditions for the existence of at least one solution of the boundary value problems for higher order nonlinear difference equations $\{{{{{\Delta^n}x(i-1)=f(i,x(i),{\Delta}x(i),{\cdots},\Delta^{n-2}x(i)),i{\in}[1,T+1],\atop%20{\Delta^m}x(0)=0,m{\in}[0,n-3],}\atop%20\Delta^{n-2}x(0)=\phi(\Delta^{n-1}(0)),}\atop%20\Delta^{n-1}x(T+1)=-\psi(\Delta^{n-2}x(T+1))}\$. are established.

• Journal of the Korean Society of Safety
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• v.17 no.1
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• pp.18-24
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• 2002

This study verified the relationship between fracture mechanics parameters(${\Delta}K,\;K_{max}$) and X-ray parameters ($(\sigma}_r,;B$) for G365 steel at elevated temperature up to $300{\circ}C$. The fatigue crack propagation test were carried out and X-ray diffraction technique according to crack length direction was applied to fatigue fractured surface. The residual stress on the fracture surface was found to increase in low ${\Delta}K$ region, reach to a maximum value at a certain value of $K_{max}$ or ${\Delta}K$ and then decrease. Residual stress was independent on stress ratio by arrangement of ${\Delta}K$ and half value breadth was independent by the arrangement of $K_{max}$. The equation of ${\sigma}_r-{\Delta}K$ was established by the experimental data. Therefore, fracture mechanics parameters could be estimated by the measurement of X-ray parameters.

• Journal of the Semiconductor & Display Technology
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• v.9 no.1
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• pp.67-71
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• 2010

Head up display’s cooling system is auto-diagnosed resulting from the external environment. The quantity of heat depending on this Head up display’s cooling system layout determines the speed of FAN for system cooling. In other words, a system’s heat quantity is planned through the air density depending on altitude, the amount of wind in air depending on FAN control condition, and the algorithm that is proportional to delta temperature. To detect the altitude, we use the criteria of delta T, which is determined by the subtracted value of LED junction temperature, and atmospheric temperature that is recorded on the Head up display system. Depending on the classification of delta T value, the altitude section is determined. While we can use GPS as the tool to detect the altitude, we should predict the change of the air density as the altitude alters, and should not just measure the altitude. And the value of delta T is used as the criterion of detecting the altitude for increasing the cooling efficiency of the car’s inner Head up display system with reflecting the speed of the FAN dependent upon the air density. In our theory, altitude is depending on the value of delta T and stabilizing or maintaining the system’s temperature by changing FAN’s rpm depending on determined value of altitude.

• Korean Journal of Food Science and Technology
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• v.31 no.3
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• pp.575-580
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• 1999

In this study, the quality changes of Hoelen was investigated, which were color differences, browning degrees, total phenolic compounds and electron donating abilities to optimize drying condition using hot air and far infrared drying by changing conditions such as temperatures, air velocities and radiation distances. In color values, ${\Delta}b\;value$ decreased with increasing temperatures, while ${\Delta}L$, ${\Delta}a$ and ${\Delta}E\;value$ increased. The browning degrees showed the similar tendency with the color values. Total phenolic components of Hoelen decreased with increasing drying temperature and air velocity, and decreasing radiation distance. On the other hand, there was no significant difference in the changes of electron donating abilities (EDA) of Hoelen among drying methods and conditions. As a result, the hot air drying was more effective method than the far infrared was.

• Journal of the Korean Chemical Society
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• v.36 no.4
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• pp.517-522
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• 1992

The reaction of ${\beta}$-picoline with substituted benzoyl chlorides has been studied by means of conductometry under various pressures in acetonitrile. From the values of pseudo-first order and second order rate constants, the activation parameters (${\Delta}V{\neq}$, ${\Delta}{\beta}{\neq}$, ${\Delta}H{\neq}$, ${\Delta}S{\neq}$ and ${\Delta}G{\neq}$) and the pressure dependence of Hammett ${\rho}$ value were studied. The activation volume, the activation compressibility coefficient and the activation entropy were all negative. By increasing pressure the rate constant and Hammett ${\rho}$ value were increased, and the reaction mechanism was proceed in bond formation favored.

• Proceedings of the KSME Conference
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• 2001.11a
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• pp.317-323
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• 2001

This study verified the relationship between fracture mechanics parameters$({\Delta}K,\;{\Delta}K_{eff},\;K_{max})$ and X-ray parameters $(\sigma_r,\;B)$ for SG365 steel at elevated temperature up to $300^{\circ}C$. The fatigue crack propagation test were carried out and X-ray diffraction technique according to crack length direction was applied to fatigue fractured surface. The residual stress on the fracture surface was found to increase low ${\Delta}K$ region, reach to a maximum value at a certain value of $K_{max}\;or\;{\Delta}K$ and then decrease. Residual stress were independent on stress ratio by arrangement of ${\Delta}K$ and half value breadth were independent by the arrangement of $K_{max}$. The equation of $\sigma_r-{\Delta}K$ was established by the experimental data. Therefore, fracture mechanics parameters could be estimated by the measurement of X-ray parameters.

• The Journal of Korean Academy of Prosthodontics
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• v.42 no.5
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• pp.514-523
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• 2004

Statement of problem: All-ceramic restorations have been advocated for superior esthetics. Various post and core systems have been used to improve the strength of damaged teeth, but it is unclear whether they affect the final shade of finished all-ceramic restorations. Purpose: The influence of different types of post and core systems on light transmission through all-ceramic crowns was assessed by spectrophotometric analysis. Also the masking effect of different thickness of ceramic ingot was evaluated. Material and Methods : Forty-five sample disks (15mm in diameter) at several thickness(1.0, 1.5, 2.0mm) and value(shade 100, 200, 300) were made in heat pressed ceramic(IPS-Empress). Background specimens simulating gold-alloy cast posts(Type III casting gold alloy), metal posts(Ni-Cr casting alloy) and ceramic posts(CosmoPost) were fabrica-ted. Resin composite(Z250, A3 shade) was used as a tooth substrate reference. For each combination, the change in color was measured with a spectrophotometer. Readings were performed for 2 conditions (1) ability of ceramic to mask the core in relation to its thickness(1.0, 1.5, or 2.0mm) ; (2) influence of post and core types on the final color of the ceramic. Data were recorded according to the CIE $L^*a^*b^*$ systems and color difference($\Delta$E) was calculated. Results: 100 shade ingot: when ceramic thickness was 1.0mm, $\Delta$E value for ceramic post larger than 1 but $\Delta$E value for metal and gold post was larger than 2. For ceramic thickness of 1.5mm, only $\Delta$E value for metal was larger than 2, and the other samples' $\Delta$E value was smaller than 2. For ceramic thickness of 2.0mm, $\Delta$E values for all specimens was smaller than 2. 200 shade ingot: when ceramic thickness was 1.0mm, $\Delta$E value for ceramic post was smaller than 1 but $\Delta$E value for metal and gold post was larger than 2. For ceramic thickness of 1.5 mm, only the $\Delta$E value for metal was larger than 2, and the other samples' $\Delta$E value was smaller than 2. For ceramic thickness of 2.0mm, $\Delta$E values for all specimens was smaller than 1. 300 shade ingot: when ceramic thickness was 1.0mm, only $\Delta$E value for metal was larger than 2 and the other samples' $\Delta$E value was smaller than 2. For ceramic thickness of 1.5mm, $\Delta$E values for all specimens was smaller than 1. For ceramic thickness of 2.0mm, $\Delta$E values for all specimens was smaller than 1. Conclusion: The final esthetic result of the IPS-Empress glass-ceramic restoration was not affected by the presence of different core materials when the thickness was more than 2.0 mm. When ceramic thickness decreases to 1.5mm, it is advised to take the substrate aspects into consideration. If the ceramic thickness is less than 1.0mm, using the tooth color matched substrate is strongly recommended.

• Journal of the Korean Institute of Telematics and Electronics C
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• v.34C no.4
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• pp.26-35
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• 1997

This paper proposes a multi-bit $\Sigma\Delta$ modulator arcitecture which eliminates signal clipping problem. To avoid signal clipping, the output values of intgrators are monitored and modified by a reference value. This oepration is recorded as a digital code to restore actual signal value. Due to the digital code, the substraction of feedback value from the multi-bit quantizer can be calculated by a digital adder and this simplifies dAC operation making the accurate DAC of conventional multi-bit $\Sigma\Delta$ modulator scheme unnecessary. These features make N-th modulator can be implemented by sharing an integrator among N stages to decrease the required chip area. As an experimental example, a 4th order .sum..DELTA. modulator with oversampling ratio of 64 was simulated to show over 130 DB SNR at rail-to-rail input sinusoidal signal.

• Journal of Microbiology and Biotechnology
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• v.12 no.1
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• pp.149-152
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• 2002

The effect of pressure on the catalytic properties of glutamate racemase from Aquifex pyrophilus, an extremophilic bacterium, was investigated. The activation volume for the overall reaction $({\Delta}V^{\neq})$ and catalysis $({{Delta}V_{cat}}^{\neq})$ was -96.97 ml/mol and 4.97 ml/mol, respectively, while the reaction volume for the substrate binding (${\Delta}V_{K_m^-1}$) was -101.94 ml/mol. The large negative ${\Delta}V^{\neq}$ for the overall reaction indicated that the pressurization of glutamate racemase resulted in enhanced catalytic efficiencies. In addition, this value was also due to the large negative ${Delta}V_{K_m^-1}$ for the substrate binding. The negative value of ${Delta}V_{K_m^-1}$ implied that the conformational changes in the enzyme molecule occurred during the substrate binding process, thereby increasing the degree of hydration. The small value of ${{Delta}V_{cat}}^{\neq}$suggested that the pressure did not affect the glutamate racemase catalysis after the substrate binding.

• Journal of Environmental Health Sciences
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• v.28 no.5
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• pp.4-12
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• 2002

It is well-known method to use Ethylene Oxide (ETO) as a fumigant to preserve cultural heritage from the attack of some bacteria and insects. In this article, we investigated co]or change of some cultural material upon treating ETO. The cultural material was selected from Korean paper (hanji), ancient books, blue prints, pigments (DA, DB, DC, DD, DE and DF). hemp cloths, and colored pictures (DG, DH, Dl, DJ, DK). The $\Delta$E value in chromaticity coordinates for each item was obtained upon treatment with ETO at concentration of 200, 250, 380, 500, 710 g/m$^3$ respectively. The $\Delta$E value was derived from the equation of L*at with the data checked 24 hr, 48 hr, and 72 hrs respectively. The Korean papers(hanji) showed slightly change in color by $\Delta$E 0.8. In the case of ancient books, it showed $\Delta$E 2.91 which was easily distinguishable with the naked eyes. For the almost 73％ of blue prints, the value of $\Delta$E was as much as more than 4.0 that it is recommended not to use. In the case of pigments, the value of $\Delta$E was ranged from 0.15 up to 4.0 so that it should be very careful before use. The hemp cloth dyed with natural indigo showed less than 1.00 in $\Delta$E, while various colored hemp cloth showed wide range of $\Delta$E from 1.00 to 4.00. Finally, from the fact that the color change was as small as less than 1.00 for the colored pictures, it is thought that treatment with ETO is one of method to be used to this purpose.