• Journal of Powder Materials
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• v.24 no.1
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• pp.11-16
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• 2017

In this study, simple chemical synthesis of green emitting Cd-free InP/ZnS QDs is accomplished by reacting In, P, Zn, and S precursors by one-pot process. The particle size and the optical properties were tailored, by controlling various experimental conditions, including [In]/[MA] (MA: myristic acid) mole ratio, reaction temperature and reaction time. The results of ultraviolet-visible spectroscopy (UV-vis), and of photoluminescence (PL), reveal that the exciton emission of InP was improved by surface coating, with a layer of ZnS. We report the correlation between each experimental condition and the luminescent properties of InP/ZnS core/shell QDs. Transmission electron microscopy (TEM), and X-ray powder diffraction (XRD) techniques were used to characterize the as-synthesized QDs. In contrast to core nanoparticles, InP/ZnS core/shell treated with surface coating shows a clear ultraviolet peak. Besides this work, we need to study what clearly determines the shell kinetic growth mechanism of InP/ZnS core shell QDs.

• Journal of Powder Materials
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• v.21 no.3
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• pp.202-206
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• 2014

Leaching of MOCVD dust in the LED industry is an essential stage for hydro-metallurgical recovery of pure Ga and In. To recover Ga and In, the leaching behavior of MOCVD scrap of an LED, which contains significant amounts of Ga, In, Al and Fe in various phases, has been investigated. The leaching process must be performed effectively to maximize recovery of Ga and In metals using the most efficient lixiviant. Crystalline structure and metallic composition of the raw MOCVD dust were analyzed prior to digestion. Subsequently, various mineral acids were tested to comprehensively study and optimize the leaching parameters such as acidity, pulp density, temperature and time. The most effective leaching of Ga and In was observed for a boiling 4 M HCl solution vigorously stirred at 400 rpm. Phase transformation of GaN into gallium oxide by heat treatment also improved the leaching efficiency of Ga. Subsequently high purity Ga and In can be recovered by series of hydro processes.

• Journal of Powder Materials
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• v.19 no.3
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• pp.210-214
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• 2012

Mass production-capable $Li_2MnSiO_4$ powder was synthesized for use as cathode material in state-of-the-art lithium-ion batteries. These batteries are main powder sources for high tech-end digital electronic equipments and electric vehicles in the near future and they must possess high specific capacity and durable charge-discharge characteristics. Amorphous silicone was quite superior to crystalline one as starting material to fabricate silicone oxide with high reactivity between precursors of sol-gel type reaction intermediates. The amorphous silicone starting material also has beneficial effect of efficiently controlling secondary phases, most notably $Li_xSiO_x$. Lastly, carbon was coated on $Li_2MnSiO_4$ powders by using sucrose to afford some improved electrical conductivity. The carbon-coated $Li_2MnSiO_4$ cathode material was further characterized using SEM, XRD, and galvanostatic charge/discharge test method for morphological and electrochemical examinations. Coin cell was subject to 1.5-4.8 V at C/20, where 74 mAh/g was observed during primary discharge cycle.

• Resources Recycling
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• v.24 no.4
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• pp.50-55
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• 2015

In this study, we have investigated solvent extraction of Ga and recovery of high pure Ga solution from MOCVD dust for manufacturing of LED chip. Effect of extractan, concentration of extractant were examined for choosing the more effective extractant and high pure Ga solution was fabricated by multi-stage extraction/stripping process. For extraction/separation of Ga based on the analysis of raw-material in previous study, 3 different extractants PC 99A, DP-8R, Cyanex 272 has been investigated and the extraction efficiency of 1.5 M Cyanex 272 was 43.8%. It was conformed that extraction efficiency of Ga was 83% in multi-stage extraction and 5N high purity Ga stripping solution without impurities also obtained.

• IEIE Transactions on Smart Processing and Computing
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• v.6 no.2
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• pp.85-92
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• 2017

This paper presents a dehazing method based on a fuzzy membership function and variational method. The proposed algorithm consists of three steps: i) estimate transmission through a pixel-based operation using a fuzzy membership function, ii) refine the transmission using an L1-norm-based regularization method, and iii) obtain the result of haze removal based on a hazy image formation model using the refined transmission. In order to prevent color distortion of the sky region seen in conventional methods, we use a trapezoid-type fuzzy membership function. The proposed method acquires high-quality images without halo artifacts and loss of color contrast.

• Korean Journal of Remote Sensing
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• v.1 no.1
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• pp.29-37
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• 1985

A low cost image processing system based on a CROMEMCO microcomputer called KAIS-MIPS, is developed for processing remotely sensed Landsat data. It hardware system can be easily interfacd with other peripheral devices. The software system provides flexibility, expansibility, portability, and maintainability as well as extensive processing capacity. As an example, processing and land use classification of Landsat 2 data for the Inchun city and its 6vicinity in Korea are provided.

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2006.09b
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• pp.907.1-907.1
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• 2006

• Journal of Powder Materials
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• v.21 no.2
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• pp.142-146
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• 2014

Fundamental experiences have been studied for development of pre-treatment process of Sn by-products such as solders. Dry and wet separation/recovery processes were considered by the differences of physical properties. The by-products, which are analyzed by solder metal and oxides. The metal and oxide were simply separated by dry ball-milling process for 12 hours, after that recovery metal powder might be reusable as lead or lead-free solders. In terms of wet separation process, samples were dissolved in $HNO_3+H_2O_2$ and the precipitation were analyzed by $SnO_2$. Overall efficiency of recovery might be increasing via developing simple pre-treatment process.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.27 no.5
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• pp.268-273
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• 2017

In this study, nickel hydroxide crystalline powders were synthesized by continuous reaction in the taylor fluid flow using nickel chloride, nickel sulphate and sodium hydroxide as raw materials and compared with those prepared by a conventional batch type reaction. The crystallinity of nickel hydroxide prepared by the Taylor fluid flow reaction was higher than that of nickel hydroxide obtained by batch reaction. The particle size of nickel hydroxide decreased about 2.5 to 3.6 times, and the specific surface area was increased.

• Proceedings of the Korean Nuclear Society Conference
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• 1997.05a
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• pp.133-138
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• 1997

For a long time, a number of alarm processing techniques have been researched to reduce the number of actuated alarms for operators to deal with effectively during the abnormal as well as the normal conditions. However, the strategy that the only systems with a few clear technologies should be used as a part of an alarm annunciation system has been adopted considering the effectiveness and the reliability in actual alarm processing systems. Therefore, alarm processing systems have difficult knowledge-base maintenance problems and limited expansion or enhancement defects. To solve these shortcomings, the integrated knowledge-base which can express the general information related to all the alarm processing techniques is proposed and its management tool, Knowledge Input Tool for Alarm (KIT-A) which can handle the data of the knowledge-base efficiently is developed. Since the integrated knowledge-base with KIT-A can manipulate all the alarm information without the modification of alarm processing system itself, it is expected to considerably advance the overall capability of maintenance and enhancement of the alarm processing systems.