• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
• /
• v.10 no.4
• /
• pp.281-294
• /
• 2012

The current status of the computer codes for the analysis of coupled thermal-hydrological-mechanical behavior occurred in a high-level waste repository was investigated. Based on the reported results on the comparison between the predictions using the computer codes and the experimental data from the in-situ tests, the reliability of the existing computer codes was analyzed. The presented codes simulated considerably well the coupled thermal-hydrological-mechanical behavior in the near-field rock of the repository without buffer, but the predictions for the engineered barrier system of the repository located at saturated hard rock were not satisfactory. To apply the current thermal-hydrological-mechanical models to the assessment of the performance of engineered barrier system, a major improvement on the mathematical models which analyze the distribution of water content and total pressure in the buffer is required.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
• /
• v.6 no.2
• /
• pp.101-109
• /
• 2008

For the Kyungju bentonite which is considered as a candidate material for the buffer and backfill in the high-level waste repository, the thermal conductivities of compacted bentonite and a bentonite-sand mixture were measured. The thermal conductivities of the compacted bentonites with a dry density of 1.2 to $1.8\;Mg/m^3$ and the bentonite-sand mixture with a dry density of 1.6 and $1.8\;Mg/m^3$ were measured within the gravimetric water content range of 10wt% to 20wt% and the sand fraction range of 10 to 30wt%. The thermal conductivity of compacted bentonite and a bentonite-sand mixture increases with increasing dry density and sand weight fraction in the case of constant water weight fraction, and increases with increasing water weight fraction and sand weight fraction in the case of constant dry density. The empirical correlations to describe the thermal conductivity of compacted bentonite and a bentonite-sand mixture as a function of water fraction at each dry density were suggested. These correlations can predict the thermal conductivities of bentonite and a bentonite-sand mixture with a difference below 10%.

• Journal of the Korea Furniture Society
• /
• v.10 no.1
• /
• pp.95-102
• /
• 1999

The objective of this paper was the development of boards made from waste newspapers. The boards were produced from particle ONP(old newspaper) to reduce energy consumption in the board production process. ONP boards bonded with polyurethan adhesives(PU) were produced on a laboratory scale, and their physical and mechanical properties were examined. The average density of the ONP was $0.48g/cm^3$, and the densities of the boards were $0.50-0.90g/cm^3$. Therefore, th compaction ratios of the boards were in the range of 1.04-1.88. The results obtained were as follows: 1) An increase in board density results in a corresponding improvement in bending properties. 2) An increase in board density results in increased thermal conductivity. 3) In this research, ONP board can be used only for interior applications. To gain exrerior applications, the dimensional stability properties(thickness swelling and water absorption) need to be improved.

• Journal of Korean Society on Water Environment
• /
• v.35 no.4
• /
• pp.299-307
• /
• 2019

The purpose of this study was to investigate the effect of low temperature thermal pre-treatment on biodegradation of waste activated sludge for anaerobic digestion as a countermeasure for increasing sludge generation. The experimental condition was accomplished in 2 %, 4 %, and 6 % TS concentration, and $70^{\circ}C$, $80^{\circ}C$, $90^{\circ}C$ of temperature for a maximum of 120 minutes retention time. Then, it was followed by analysis of physical/chemical properties, BMP test and composition of biogas. The biogas characteristic was evaluated by applying the modified Gomperz model. As a result, solubility of dissolved substrate, such as $SCOD_{Cr}$, soluble carbohydrate, and soluble protein, and biogas production increased as temperature increased. Solubilization efficiency at $90^{\circ}C$ was 18.4 %, 17.03 % and 16.88% in 2 %, 4 %, and 6 % TS concentration respectively. Also, solubilization rates of carbohydrate and protein similarly increased. BMP test results also showed that methane production in excess sludge increased to 0.194, 0.187 and $0.182m^3/kg$ VS. respectively, and lag phase decreased to 0.145, 0.220, 0.351 day due to acceleration of the hydrolysis step. Consequently, low-temperature thermal pre-treatment could increase biodegradability of sludge, positively affecting biogas production and sludge reduction.

• Proceedings of the Korean Institute of Building Construction Conference
• /
• 2012.05a
• /
• pp.217-218
• /
• 2012

To prevent energy waste in buildings used heat insulator. Heat insulator materials can be classified inorganic and organic. The organic material is be toxic gas emission, when a fire occurs. And it has lower water resistance. The inorganic material is heavy and worse thermal performance than organic materials. This study focused on thermal conductivity and density of inorganic foam material for using industrial by-products materials.

• Journal of Environmental Science International
• /
• v.13 no.4
• /
• pp.403-412
• /
• 2004

Waste water-soluble cutting oil was treated with WI type #1 and WI type #2. The properties of the original water-soluble cutting oil were pH=l0.4, viscosity=1.4cP, CODcr=44,750 ppm, and TOC=10,569 ppm. However, the properties of the oil used for more than 3 months were changed to pH=7.82, viscosity=2.1cP, CODcr=151,000 ppm, and TOC=74,556 ppm. It might be attributed to the fact that molecular chains were cut due to thermal oxidation and impurities such as metal chips were incorporated in to the oil during the operation processes. To prevent the putrefaction of oil, the sterilization effect of ozone and UV on the microorganism in the oil was investigated. Ozone treatment showed that 99.99% of the microorganism was annihilated with 30 minutes contact time and 60 minutes were necessary for the same effect when UV was used. Ozone treatment could cut molecular chains of the oil due to strong sterilization power, which was evidenced by the increase of TOC from 25,132 ppm at instantaneous contact to 28,888 ppm at 30 minutes contact time. However, UV treatment didn't show severe changes in TOC values and thus, seemed to cause of severe cut of molecular chains. When the activated carbon was used to treat the waste water-soluble cutting oil, TOC decreased to 25,417 ppm with 0.lg carbon and to 15,946 ppm with 5.0g carbon. This results indicated that the waste oil of small molecular chains could be eliminated by adsorption. From the results, it could be concluded that these treatment techniques could be proposed to remove the waste oil of small molecular chains resulting in the degradation of the oil properties. In addition, these experimental results could be used for the correlation with future works such as investigation of the molecular distribution according to the sizes, lengths, and molecular weight of the chains.

• International Journal of Air-Conditioning and Refrigeration
• /
• v.11 no.2
• /
• pp.73-81
• /
• 2003

The performance of heat exchanger using oscillating heat pipe (OHP) for low temperature waste heat recovery was evaluated. OHP used in this study was made from low finned copper tubes connected by many turns to become the closed loop of serpentine structure. The OHP heat exchanger was formed into shell and tube type. R-22 and R-141b were used as the working fluids of OHP with a fill ratio of 40 vol.%. Water was used as the working fluid of shell side. As the experimental parameters, the inlet temperature difference between heating and cooling water and the mass velocity of water were changed. The mass velocity of water was changed from 30 kg/$m^2$s to 92 kg/$m^2$s. The experimental results showed that the heat recovery rate linearly increased as the mass velocity and the inlet temperature difference of water increased. Finally, the performance of OHP heat exchanger was evaluated by $\varepsilon$-NTU method. It was found that the effectiveness would be 80% if NTU were about 1.5.

• Journal of the Korean Ceramic Society
• /
• v.46 no.3
• /
• pp.275-281
• /
• 2009

Porous materials were manufactured by hydrothermal treatment of waste bottle glass without foam agent. Factorial design was applied to analyze data by statistical methods and deal with the important factors for a process. The largest effect for porosity was for temperature of hydrothermal treatment. Amount of water and temperature-water interaction appeared to have little effect. The particle size of raw material was also identified as a major factor by one-way ANOVA and the porosity decreased as the size increased. The sintering temperature was not statistically significant for the porosity but was significant for the pore size. The porous material had compressive strength and thermal conductivity comparing with those of ALC (autoclaved lightweight concrete), although it has higher porosity than for ALC.

• KOREAN JOURNAL OF PACKAGING SCIENCE & TECHNOLOGY
• /
• v.15 no.1
• /
• pp.25-32
• /
• 2009

It is now widely recognized that the disposal of packaging waste is an increasing environmental concern. Recent interest in polymer waste management of packaging materials has added incentive to the research. Poly(vinyl alcohol) is a readily biodegradable water-soluble polymer. However, this polymer cannot be processed by conventional extrusion technologies because the melting point of PVA is close to its decomposition temperature. Therefore, PVA films have been mostly prepared by solvent casting from water. Applications of PVA include sizing, binders, fibers, and films for agricultural chemicals and hospital laundry bags. A better understanding of PVA films, which also play important roles in the degradation of plastics, will expand the usage of PVA. Composite films based on PVA generally exhibit better mechanical and thermal properties than pure PVA. The aim of this review article is to review types, formation, and properties of PVA films and PVA based composite films used in packaging related researches.

• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.34 no.6
• /
• pp.607-613
• /
• 2010

A seawater distiller, in which the waste heat from a portable electric generator was used, with a multiple-effect diffusion still was designed. The waste gas from small generators commonly used in islands has not yet been used because it has less thermal energy; however, this waste gas can be used as a heat source for small-capacity distillers and as an additional heat source for solar stills. The proposed distiller comprises a series of closely spaced parallel partitions that are placed in contact with saline-soaked wicks. In the distiller, evaporation and condensation processes are repeated to recycle the thermal energy for increasing the distillate productivity. Experimental results show that the proposed distiller with only one-effect still can produce at least 6.7 kg/day of distilled water; the proposed distiller with a ten-effect still is expected to produce 43 kg/day of distilled water. This amount of distillate is approximately four times the maximum daily productivity of the solar stills, as determined in outdoor experiments.