• Journal of the Korean Society for Geothermal and Hydrothermal Energy
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• v.16 no.4
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• pp.1-8
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• 2020

For a central cooling system of a medical facility composed of absorption chiller and screw chiller, the study was conducted on how to minimize the energy cost. In consideration of the energy cost, the optimal operation method in which the operation method of the heat source is changed according to the size of the cooling load was derived through simulation analysis. When applying the optimal operation method, the indoor environment, energy consumption, and energy cost were analyzed and compared with the reference operation method.

• Journal of Internet Computing and Services
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• v.17 no.5
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• pp.97-110
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• 2016

Cryptanalysis is very important step for auditing and checking strength of any cryptosystem. Some of these cryptosystem ensures confidentiality and security of large information exchange from source to destination using symmetric key cryptography. The cryptanalyst investigates the strengths and identifies weakness key as well as enciphering algorithm. With increase in key size the time and effort required to guess the correct key increases so trend is increase key size from 8, 16, 24, 32, 56, 64, 128 and 256 bits to strengthen the cryptosystem and thus algorithm continues without compromise on the cost of time and computation. Automatic Variable Key (AVK) approach is an alternative to the approach of fixing up key size and adding security level with key variability adds new dimension in the development of secure cryptosystem. Likewise, whenever any new cryptographic method is invented to replace per-existing vulnerable cryptographic method, its deep analysis from all perspectives (Hacker / Cryptanalyst as well as User) is desirable and proper study and evaluation of its performance is must. This work investigates AVK based cryptic techniques, in future to exploit benefits of advances in computational methods like ANN, GA, SI etc. These techniques for cryptanalysis are changing drastically to reduce cryptographic complexity. In this paper a detailed survey and direction of development work has been conducted. The work compares these new methods with state of art approaches and presents future scope and direction from the cryptic mining perspectives.

• Journal of Microbiology and Biotechnology
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• v.8 no.6
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• pp.606-612
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• 1998

A microbial flocculant-producing gram-positive bacterium, strain TE11, was isolated from soil samples, and was identified as Bacillus subtilis by using the Midi system, the Biolog system, 16S rDNA sequence analysis, and some physiological and morphological characteristics. The maximum flocculant capsular biopolymer of TE11 strain (BCP, 4.9mg/ml) was obtained when it was grown in GA broth medium containing 3% glutamic acid, 2% glycerol, 0.5% citric acid, 0.5% $NH_4$Cl, 0.05% $MgSO_4.7H_2O,\; 0.05%\;K_2HPO_4\;,\; and\; 0.004%\; FeC1_3. 6H_2O,\; pH 7.2,\; at\; 30^{\circ}C$ for 70 h with shaking. When glycerol was used as an additional carbon source in the GA medium, TE11 produced only flocculant BCP without any by-product. The flocculant (BCP) was found to aggregate suspended kaolin and activated charcoal powder without cations, and its flocculating activity was significantly enhanced by the addition of bivalent cations such as $Ca^{2＋}.Zn^{2},\; and\; Mn^{2＋}$. The flocculation activity by addition of $Ca^{2+}$ was high in an acidic pH 4.0. In the case of $Zn^{2＋}$, high flocculating activity remained without significant loss in the broad range of pH 4.0 to 9.0.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2000.10a
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• pp.190-195
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• 2000

This paper presents the fabrication of the LNA which is operating at 2.13∼2.16 GHz for IMT-2000 lot-end receiver using series feedback and resistive decoupling circuit. Series feedback added to the source lead of a transistor keep the low noise characteristics and drop the input reflection coefficient of amplifier simultaneously. Also, it increases the stability of the LNA. Resistive decoupling circuit is suitable for input stage matching because a signal at low frequency is dissipated by a resistor in the matching network The amplifier consist of GaAs FET ATF-10136 for low noise stage and VNA-25 which is internally matched MMIC for high gain stage. The amplifier is fabricated with both the RF circuits and self bias circuit on the Teflon substrate with 3.5 permittivity. The measured results of the LNA which is fabricated using above design technique are presented more than 30 dB in gain P$\_$ldB/ 17 dB and less than 0.7 dB in noise figure, 1.5 in input$.$output SWR(Standing Wave Ratio).

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2006.11a
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• pp.129-130
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• 2006

A stoichiometric mixture of evaporating materials for $CdIn_2S_4$ single crystal thin films was prepared from horizontal furnace. To obtain the single crystal thin films, $CdIn_2S_4$ mixed crystal was deposited on thoroughly etched semi-insulating GaAs(100) substrate by hot wall epitaxy(HWE) system. The source and substrate temperatures were $630^{\circ}C$ and $420^{\circ}C$, respectively. After the as-grown $CdIn_2S_4$ single crystal thin films was annealed in Cd-, S-, and In-atmospheres, the origin of point defects of $CdIn_2S_4$ single crystal thin films has been investigated by the photoluminescence(PL) at 10 K. The native defects of $V_{cd}$, $V_s$, $Cd_{int}$, and $S_{int}$, obtained by PL measurements were classified as a donors or acceptors type. And we concluded that the heat-treatment m the S-atmosphere converted $CdIn_2S_4$ single crystal thin films to an optical p-type. Also. we confirmed that In in $CdIn_2S_4$/GaAs did not form the native defects because In in $CdIn_2S_4$ single crystal thin films existed in the form of stable bonds.

• Korean Journal of Materials Research
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• v.14 no.11
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• pp.755-763
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• 2004

A stoichiometric mixture of evaporating materials for $CuInse_2$ single crystal thin films was prepared from horizontal electric furnace. To obtain the single crystal thin films, $CuInse_2$ mixed crystal was deposited on thoroughly etched semi-insulating GaAs(100) substrate by the hot wall epitaxy (HWE) system. The source and substrate temperatures were $620^{\circ}C\;and\;410^{\circ}C$, respectively. The temperature dependence of the energy band gap of the $CuInse_2$ obtained from the absorption spectra was well described by the Varshni's relation, $E_{g}(T)=1.1851 eV - (8.99{\times}10^{-4} eV/K)T^2/(T+153 K)$. After the aa-grown $CuInse_2$ single crystal thin films was annealed in Cu-, Se-, and In-atmospheres, the origin of point defects of $CuInse_2$ single crystal thin films has been investigated by the photoluminescence(PL) at 10 K. The native defects of $V_{cu},\;V_{Se},\;Cu_{int},\;and\;Se_{int}$ obtained by PL measurements were classified as a donors or accepters type. And we concluded that the heat-treatment in the Cu-atmosphere converted $CuInse_2$ single crystal thin films to an optical n-type. Also, we confirmed that In in $CuInse_2$/GaAs did not form the native defects because In in $CuInse_2$ single crystal thin films existed in the form of stable bonds.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2006.05a
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• pp.239-242
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• 2006

LCD-BLU (Liquid Crystal Display - Back Light Unit) is one of kernel parts of LCD unit and it consists of several optical sheets(such as prism, diffuser and protector sheets), LGP (Light Guiding Plate), light source (CCFL or LED) and mold frame. The LGP of LCD-BLU is usually manufactured by forming numerous dots with $50{\sim}200$ um in diameter on it by etching process. But the surface of the etched dots of LGP is very rough due to the characteristics of the etching process during the mold fabrication, so that its light loss is high along with the dispersion of light into the surface. Accordingly, there is a limit in raising the luminance of LCD-BLU. In order to overcome the limit of current etched dot patterned LGP, optical pattern design with 50um micro-lens was applied in the present study. The micro-lens pattern fabricated by modified LiGA with thermal reflow process was applied to the optical design of LGP. The attention was paid to the effects of different aspect ratio (i.e. $0.2{\sim}0.5$) of optical pattern conditions to the brightness distribution of BLU with micro-lens patterned LGP. Finally, high aspect ratio micro-lens patterned LGP showed superior results to the one made by low aspect ratio in average luminance.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.07a
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• pp.257-265
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• 2002

A stoichiometric mixture of evaporating materials for AgInS$_2$ single crystal thin films was prepared from horizontal furnace. To obtain the single crystal thin films, AgInS$_2$ mixed crystal was deposited on thoroughly etched semi-insulating GaAs(100) substrate by the Hot Wall Epitaxy(HWE) system. The source and substrate temperatures were 680 $^{\circ}C$ and 410 $^{\circ}C$, respectively. The crystalline structure of the single crystal thin films was investigated by the photoluminescence and double crystal X-ray diffraction(DCXD). The carrier density and mobility of AgInS$_2$ single crystal thin films measured from Hall effect by van der Pauw method are 9.35${\times}$10$\^$16/ cm$\^$-3/ and 294 $\textrm{cm}^2$/V$.$s at 293 K, respectively. From the optical absorption measurement, the temperature dependence of the energy band gap on AgInS$_2$ single crystal thin films was found to be E$\_$g/(T) : 2.1365 eV - (9.89 ${\times}$ 10$\^$-3/ eV) T$^2$/(2930 + T). After the as-grown AgInS$_2$ single crystal thin films was annealed in Ag-, S-, and In-atmospheres, the origin of point defects of AgInS$_2$ single crystal thin films has been investigated by using the photoluminescence(PL) at 10 K. The native defects of V$\_$AG/, V$\_$S/, Ag$\_$int/, and S$\_$int/ obtained from PL measurements were classified as a donors or acceptors type. And we concluded that the heat-treatment in the S-atmosphere converted AgInS$_2$ single crystal thin films to an optical p-type. Also, we confirmed that In in AgInS$_2$/GaAs did not form the native defects because In in AgInS$_2$ single crystal thin films did exist in the form of stable bonds.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.11a
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• pp.141-142
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• 2008

Single crystal $ZnIn_2S_4$ layers were grown on thoroughly etched semi-insulating GaAs(100) substrate at $450^{\circ}C$ with hot wall epitaxy (HWE) system by evaporating $ZnIn_2S_4$ source at $610^{\circ}C$. The temperature dependence of the energy band gap of the $ZnIn_2S_4$ obtained from the absorption spectra was well described by the Varshni's relation, $E_g$(T) = 2.9514eV - ($7.24\times10^{-4}$ eV/K)$T^2$/(T + 489 K). After the as-grown $ZnIn_2S_4$ single crystal thin films was annealed in Zn-, S-, and In-atmospheres, the origin of point defects of $ZnIn_2S_4$ single crystal thin films has been investigated by the photoluminescence(PL) at 10 K. The native defects of $V_{Zn}$, $V_s$, $Zn_{int}$, and $S_{int}$, obtained by PL measurements were classified as a donors or acceptors type. And we concluded that the heat-treatment in the S-atmosphere converted $ZnIn_2S_4$ single crystal thin films to an optical p-type. Also, we confirmed that In in $ZnIn_2S_4$/GaAs did not form the native defects because In in $ZnIn_2S_4$ single crystal thin films existed in the form of stable bonds.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.07a
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• pp.386-391
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• 2003

Sing1e crystal $CuAlSe_2$ layers were grown on thoroughly etched semi-insulating GaAs(100) substrate at $410^{\circ}C$ with hot wall epitaxy (HWE) system by evaporating $CuAlSe_2$source at $680^{\circ}C$. The crystalline structure of the single crystal thin films was investigated by the photoluminescence(PL) and double crystal X-ray diffraction (DCXD). The carrier density and mobility of single crystal $CuAlSe_2$ thin films measured with Hall effect by van der Pauw method are $9.24{\times}10^{16}\;cm^{-3}$ and $295\;cm^2/V{\cdot}\;s$ at 293 K, respectively. The temperature dependence of the energy band gap of the $CuAlSe_2$ obtained from the absorption spectra was well described by the Varshni's relation, $E_g(T)\;=\;2.8382\;eV\;-\;(8.86\;{\times}\;10^{-4}\;eV/K)T^2/(T\;+\;155K)$. After the as-grown single crystal $CuAlSe_2$ thin films were annealed in Cu-, Se-, and Al-atmospheres, the origin of point defects of single crystal $CuAlSe_2$ thin films has been investigated by PL at 10 K. The native defects of $V_{Cd}$, $V_{Se}$, $Cd_{int}$, and $Se_{int}$ obtained by PL measurements were classified as donors or accepters. And we concluded that the heat-treatment in the Cu-atmosphere converted single crystal $CuAlSe_2$ thin films to an optical n-type. Also, we confirmed that Al in $CuAlSe_2/GaAs$ did not form the native defects because Al in single crystal $CuAlSe_2$ thin films existed in the form of stable bonds.