• International Journal of Advanced Culture Technology
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• v.3 no.2
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• pp.100-109
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• 2015

Environmental problems from petroleum-based plastic wastes have been rapidly increasing in recent years. The alternative solution is focus on the development of environmental friendly plastic derived from renewable resource. Poly(lactic acid) (PLA) is a biodegradable polymer synthesized from biomass having potential to replace the petroleum-based non-degradable polymers utilizations. PLA can be synthesized by two methods: (1) ring-opening of lactide intermediate and (2) direct polycondensation of lactic acid processes. The latter process has advantages on high yields and high purity of polymer products, materials handling and ease of process treatments. The polymerization process of PLA synthesis has been widely studied in a laboratory scale. However, the mass scale production using direct polycondensation of lactic acid has not been reported. We have investigated the kinetics and scale-up process of direct polycondensation method to produce PLA in a pilot scale. The order of reaction is 2 and activation energy of lactic acid to lactic acid oligomers is 61.58 kJ/mol. The pre-polymer was further polymerized in a solid state polymerization (SSP) process. The synthesized PLA from both the laboratory and pilot scales show the comparable properties such as melting temperature and molecular weight. The appearance of synthesized PLA is yellow-white solid powder.

• Journal of the Korean Ceramic Society
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• v.21 no.4
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• pp.323-326
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• 1984

In this study we are going to develop the process of a synthesis about BaTiO3 at the room temperature. We use BaTiO3 as a high dielectric constant in many dielectric materials and more stable in the temperature, We need high temperature over 1300$^{\circ}C$ for the synthesis of BaTiO3 by the process of industrials and there are difficulty which synthesize a final products not to have a intermediate composition. So we studied to synthesize a pure BaTiO3 from the room temperature to 90$^{\circ}C$ and also to develop the process of synthesis which can control the particle size and which has the final product not to have a intermediate composition.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.07a
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• pp.554-557
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• 2001

In this work, we had synthesis the GaN powder by direct reaction between Ga and NH$_3$at the temperature range of 1000∼1150$^{\circ}C$, and investigated the reaction condition dependence of the GaN yield and some properties of GaN powder. The synthesized powder had Platelet and prismatic shape and showed hexagonal crystalline structure with the lattice constants of a= 3.1895 ${\AA}$, c= 5.18394 ${\AA}$, and the ratio of c/a = 1.6253. The GaN powder synthesis processes were examined based on the oxidation process of mater, and found as combined with mass transport process for the initial stage and diffusion-limited reaction for the extended reaction.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.22 no.10
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• pp.966-980
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• 2011

Radar receiving echo signal provides target information - range, velocity and position by signal magnitude and Doppler shift, which are determined by target reflection characteristics and target maneuver. Target angle error is extracted from the magnitude ratio of difference channel to sum channel. In this paper, we introduce a radar Return Signal Simulation Equipment(RSSE) which is implemented for the purpose of performance analysis and evaluation of phased array multi-function radar(MFR). It generates multi-target environment with jamming signals using MC-DDS (Multi-Channel Direct Digital Synthesis), and has scalability by using the efficient hardware configuration. The performance of the developed RSSE has been evaluated under various test environments. Especially, we proved that required target detection performance is achieved by RSP(Radar Signal Processor) interfaced RSSE configuration.

• Bulletin of the Korean Chemical Society
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• v.33 no.8
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• pp.2581-2584
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• 2012

Hexafluoroisopropanol (HFIP) is explored as an effective medium for the synthesis of quinoxaline derivatives in high yields at room temperature. The solvent (HFIP) can be readily separated from reaction products and recovered in excellent purity for direct reuse.

• Journal of the Korean Ceramic Society
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• v.32 no.8
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• pp.931-937
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• 1995

AlN powder and whiskers were synthesized by direct nitridation of aluminum powder in pure nitrogen atmosphere. The nitridation reaction of aluminum powder was initiated by heating the sample to the ignition temperature and the reaction was finished in less than 3 minutes. AlN whisker-shaped morphology was observed predominantly when the sample was heated above 90$0^{\circ}C$.

• Journal of the Korean Institute of Telematics and Electronics A
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• v.28A no.1
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• pp.74-84
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• 1991

This paper presents an algorithm for technology-dependent logic optimization and technology mapping, and describes a performance-driven logic synthesis system, SILOS, implemented based on the proposed algorithm. The system analyzes circuits and resynthesizes the critical sections such that generated circuit operates opertes within time constraints, using only gate types supported by library for direct implementation. Experimental results show that the system can be a viable tool in synthesizing high-performance logic circuits.

• Bulletin of the Korean Chemical Society
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• v.20 no.8
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• pp.875-878
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• 1999

A new concept ？？soft solution processing？？ has been introduced to fabricate advanced solid state materials in an economical, environmentally friendly, and energy and material efficient way. The prepared films show the desired and prospective properties despite of low temperature synthesis and no post-synthesis annealing. Successful examples demonstrate that soft solution processing is capable of preparing advanced materials with planned properties through the easy control of reaction conditions in a suitable aqueous solution in a single synthetic step without huge energy consumption and without any sophisticated equipment.

• Bulletin of the Korean Chemical Society
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• v.28 no.10
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• pp.1665-1669
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• 2007

A direct regioselective α-hydroxyamination of α-branched aldehydes with nitrosobenzene using cis-5-benzylproline as catalyst has been developed for the preparation of α-hydroxyamino aldehydes possessing a quaternary carbon center. Such compounds are versatile building blocks for the synthesis of quaternary α- amino acids, β-amino alcohols, and 1,2-diamines.

• Proceedings of the KIEE Conference
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• 1991.07a
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• pp.217-220
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• 1991

Ni-Zn ferrite powders in the few hundred angstrum size range and up have been synthesized by a wet direct method. The coprecipitate were prepared by adding alkaline solution into the constituent metal ions solution. and subsequent calcined at various temperature. At 95, the particles were ultrafine spherical shaped particles of about 500(A) in diameter.