• Nuclear Engineering and Technology
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• v.11 no.3
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• pp.203-212
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• 1979

The thermal decomposition of simulated Magnox highly active waste and of HARVEST feed slurries (SW and SG) which include tile glass forming chemicals has been studied. The waste and the slurries are almost completely calcined by 500-55$0^{\circ}C$. The colour of the solids from the slurries varies little until about 90$0^{\circ}C$ when it darkens considerably. The slurries begin to vitrify at this temperature and are completely vitrified at 1000-105$0^{\circ}C$. On the other hand. the sulphate impurity in SN slurry causes a yellow phase to separate above 75$0^{\circ}C$. The density of the intermediate solids is fairly low until 650$^{\circ}$-$700^{\circ}C$ is reached. This temperature seems to mark the onset of fluxing as tile density rises quickly to 2g/㎤ at 700$^{\circ}$ -80$0^{\circ}C$. The strengh of the solids decreases with temperature up to 50$0^{\circ}C$, and then rises as the solids begin to sinter. Below 50$0^{\circ}C$ the SN solids are the stronger. suggesting that the impurity renders this silica more reactive.

• Nuclear Engineering and Technology
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• v.20 no.2
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• pp.120-131
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• 1988

A souce term model describes mathematically the source of radionuclides as they begin slow migration and decay in deep groundwater. Various source term models based on mass-transfer analysis and measurement-based source term models are reviewed. Ganerally, two processes are involved in leaching or dissolution: (1) chemical reactions and (2) mass transfer by diffusion. The chemical reaction controls the dissolution rates only during the early stage of exposure to groundwater. The exterior-field mass transfer may control the long term dissolution rates from the waste solid in a geologic repository. Mass-transfer analyses re3y on detailed and careful application of the governing equations that describe the mechanistic processes of transport of material between and within phases. If used correctly, source term models based on mass-transfer theory are valuable and necessary tools for developing reliable predictions.

• Proceedings of the Korean Radioactive Waste Society Conference
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• 2003.11a
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• pp.220-225
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• 2003

Generally, liquid radioactive wastes generated in nuclear power plant exist in powder form which do not contain moisture through the evaporating process of the Liquid Waste Management System and drying process of the Concentrated Waste Drying System. This powder form wastes are blended homogeneously with paraffin solidification agent and packed in metal drum to ensure its stability during handling and disposal. However, it was experienced that the powder form wastes were not blended homogeneously and separated into two layers in metal drum, on the other hand, a Portion of powder was adhered and solidified to the Inside parts of facility during the blending process. And the flaw of blending process above would come in case the mole ratio of Boron to Sodium in liquid radioactive wastes exceeds 0.2.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.29 no.2C
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• pp.315-323
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• 2004

In this paper we present a method to generate the bit stream of static video test patterns for testing the picture quality in DTV system. The proposed user-defined quantization table is suitable for the static video test pattern and for minimizing the deterioration of picture quality by quantization, the underflow or overflow of video buffer generated on the process of coding the static video test pattern is compensated by a adaptive zero stuffing algorithm so that optimal picture quality is implemented. Experimental result showed that the test pattern stream encoded by MPEG-2 software with the proposed algorithm had a stable bit rate and good video quality during the decoding process, which is about 3 dB higher than that of the conventional case.

• Journal of Energy Engineering
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• v.4 no.3
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• pp.372-378
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• 1995

분류층 석탄가스 반응온도에서 slag의 배출 조건을 원활하게 유지하기 위하여 CaCO3를 flux로 사용한 용융특성을 파악하였다. 첨가에 의한 용융온도는 flux 주입량에 따라 감소하다가 증가하였다. 최저 용융온도의 범위는 ash중 CaO 농도기준 30-40%의 범위에서 나타났으며, Base/Acid ratio에 따라 최소 용융온도는 ash중 무기물간의 eutetic effect가 작용함을 알 수 있었다. 고온에서의 slag 조성은 ash의 조성과 비교시 알카리 산화물의 휘발화와 SO2의 감소를 보여주고 있으며, salg중 환원성 가스가 증가함에 따라 금속 산화물의 환원에 의해 SiO2 조성은 증가하였다. CaCO3를 혼합한 시료를 질소분위기하에서 조제하여 점도를 측정한 결과, low silica ash의 경우 낮은 점도치를 보여주나, 250 poise 이하의 범위에서 고화되는 현상이 발생하였다. high silica ash에서는 CaCO3 투입에 의해 slag 점도는 감소하였는데, slag 분석 결과 CaO가 산소 제공물질(oxide doner)로 작용하여 silicate의 응집현상을 억제하는 것으로 나타났다.

• Proceedings of the Korean Nuclear Society Conference
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• 1996.05b
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• pp.707-712
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• 1996

중대사고시 원자로 압력용기내 또는 원자로 공동(cavity) 내에서의 노심용융물은 주입되는 물로 인하여 물과 접촉하는 표면이 냉각되면서 피막층(crust)이 형성된다. 이러한 피막층의 형성은 노심용융물과 냉각수 사이의 열전달 현상에 영향을 미치며 중대사고 발생시 사고 진행에 중요한 역할을 한다. 본 연구에서는 이러한 용융물의 피막층 형성의 해석모델을 수립하기 위해 전이현상과 전도와 대류를 포함하는 2차원 열전달과 상변화를 수반하는 문제를 포함하는 운동량방정식과 에너지방정식을 2차원으로 구성하였으며 에너지방정식은 엔탈피의 함수로 나타내었다. 그리고 이러한 2차원 지배방정식을 해석하기 위해 유한차분법 및 SIMPIER 알고리즘을 이용하였다. 비교대상으로는 한국원자력연구소에서 수행한 냉각수의 비등과 기체주입 효과가 고려되지 않은 실험을 대상으로 하였다. 계산결과 용융물의 피막층은 파동(wave) 형태로 형성되었으며 일정시간이 경과하면 변화가 없는 안정한 상태가 되었다. 용융물 내에서의 온도분포는 액체상태일 경우에는 하부가열면과 상변화가 일어나는 경계면부근을 제외하고는 거의 일정한 온도분포를 나타내고 있으며 용융물이 고화된 피막층에서는 급격한 온도변화를 보여주고 있다.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.06a
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• pp.92-92
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• 2008

PDP의 저가화, 친환경화, 고화질화는 타 디스플레이와 경쟁을 위해 필수적이고 그로 인한 소재의 개발이 필요하다. 저가화는 부품, 공정에서도 가능하지만 소재에서의 원가가 상당부분을 차지하고 있기 때문에 소재 개발이 중요하며, 친환경화는 현재 유전체에서 많이 사용되고 있는 유해소재를 친환경 소재로 대체함으로써 개발이 이루어지고 있다. 그래서 우리는 현재 PDP에서 전극물질로 사용되어지는 고가의 Ag를 Gu입자에 Ag 박막으로 코팅한 Ag/Cu 전극 powder를 사용하여 저가의 전극 paste를 만들고 스크린 프린터와 노광장비를 사용하여 전극을 형성하였다. 그 후 친환경적인 Pb free 투명유전체를 입히고 전극과의 상호 매칭성을 연구 하였다. 결과적으로 기존 PDP 공정에서 볼 수 없었던 황변현상, 전극착색현상, 전극입자의 터짐성 등 많은 현상이 일어났지만, 기존 공정 온도보다 낮은 온도로 공정한 결과, 이러한 문제들이 줄어드는 것을 확인하였다. 이로써 공정단가의 저가화와 제품의 친환경을 가면서도 기존과 차이가 제품을 실현할 수 있을 것이다.

• Journal of the Speleological Society of Korea
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• no.67
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• pp.1-9
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• 2005

The lava-calcification which was found in Geunjisul located in Jeju-do (Korea) was investigated to analyse the cause of calcification through the internal factor of cave structure and surroundings in company with relevant ecological system. The volcanic cave is degenerated after formation from volcano lava extravasation, however, the cave became more stronger with solidification and petrification by the reinforced structure of calcification as the cement in concrete buildings unprecedentedly if the lava-calcification occurred in the cave. Such a Progressive Phenomena of lava-calcification was verified in progress first in Geonjigul located at Hyubjae-ri, but those would be found in other simiiar case of caves distributed and connected with seaside of shelly sand beach.

• Nuclear Engineering and Technology
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• v.8 no.4
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• pp.231-242
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• 1976

The effects of temperature and pressure of leaching water on the leaching of radionuclides from bitumen-waste products were studied. The principal results are as follows: The fraction of $^{90}$ Sr and $^{137}$ Cs leached for periods of up to 120 days at 8atm was 2.1$\times$10$^{-6}$ ($\textrm{cm}^2$/g)$^{-1}$ , day$^{-1}$ and 6.02$\times$10$^{-5}$ ($\textrm{cm}^2$/g)$^{-1}$ day$^{-1}$ respectively and at 5$^{\circ}C$, 1.7$\times$10$^{-5}$ ($\textrm{cm}^2$/g)$^{-1}$ day$^{-1}$ and 4.01$\times$10$^{-5}$ ($\textrm{cm}^2$/g)$^{-1}$ day$^{-1}$ respectively. These values were lower than those in atmospheric pressure and room temperature. No diffence in the leaching rate with sea and distilled water was observed for the bitumen-waste products containing 40wt% salts. It appears that these results could be saved by improving safety in the dumping of sea. The effect of the softening point of pure asphalt or bitumen-waste product by $^{60}$ Co irradiation was increased with increasing total dose. Irradiation of asphalts at a total dose of 5.8$\times$10$^{8}$ rad showed no evidence of volume and caused no swelling. The functional groups of blown asphalt by infrared spectra are also identified.

• Applied Chemistry for Engineering
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• v.24 no.2
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• pp.144-147
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• 2013

Sweating, which is the excretion of oil on the surface of a solid product containing several kinds of pigments in oil and is also solidified with wax, is a unique phenomenon often observed on the surface of cover make-up or lipstick. The cause of sweating is an imbalanced formula. Many studies have been conducted to decrease the symptoms of sweating in the field of cosmetics. Differential scanning calorimetry (DSC) is a thermo-analytical technique that measures the amount of heat required to increase the temperature of a sample as a function of temperature or time under certain conditions. DSC has been used to determine the thermal properties of oil/wax structures. This study investigates how the thermal characteristics correlate with the sweating symptoms. An oil/wax formulation with an optimal melting point was studied in an attempt to make a stable product by considering the thermal properties that represent minimal structural changes with temperature variation. In addition, the sweating of the oil/wax formulation was observed over a various temperature range. As a result, it was found that sweating was minimized when the structure remained static or little bit changed over a variety of temperatures.