• The Journal of Engineering Geology
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• v.13 no.2
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• pp.171-191
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• 2003

The objective of this present study is to understand long term(500 years) thermohydromechanical interaction behavior on joints adjacent to a repository cavern, when high level radioactive wastes are disposed of within discontinuous granitic rock masses, and then, to contribute this understanding to the development of a disposal concept. The model includes a saturated discontinuous granitic rock mass, PWR spent nuclear fuels in a disposal canister surrounded with compacted bentonite inside a deposition hole, and mixed bentonite backfilled in the rest of the space within a repository cavern. It is assumed that two joint sets exist within a model. Joint set 1 includes joints of $56^{\circ}$ dip angle, spaced 20m apart, and joint set 2 is in the perpendicular direction to joint set 1 and includes joints of $34^{\circ}$ dip angle, spaced 20m apart. The two dimensional distinct element code, UDEC is used for the analysis. To understand the joint behavior adjacent to the repository cavern, Barton-Bandis joint model is used. Effect of the decay heat from PWR spent fuels on the repository model has been analyzed, and a steady state flow algorithm is used for the hydraulic analysis.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.35 no.7
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• pp.693-699
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• 2011

Internal combustion engines running on syngas, which can be obtained from biomass or organic wastes, are expected to be one of the suitable alternatives for power generation, because they are environment-friendly and do not contribute to the depletion of fossil fuels. However, syngas has variable compositions and a lower heating value than pure natural gas, owing to which the combustion conditions need to be adjusted in order to achieve stable combustion. In this study, a gas that has the same characteristics as syngas, such as low heating value (LHV), was produced by mixing $N_2$ with compressed natural gas (CNG). In addition, this study investigates the combustion characteristics of syngas when it is mixed with hydrogen in a ratio ranging from 10% to 30% with a constant LHV of total gas.

• Journal of the Korea Organic Resources Recycling Association
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• v.3 no.2
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• pp.47-57
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• 1995

The purpose of this study was to investigate the effect of mechanical mixing intensity on composting. The major parameters investigated were the mixing intensity and initial moisture content. Laboratory scale composting reactors with mixing equipment were used in this study. Wastes used for the study were raw nightsoil sludge, nightsoil sludge after vacuum evaporation treatment and pig manure. When moisture contents were 60% and 63%, amount of organic material degraded in the continuous mixing reactors was higher than that in the intermittent mixing reactors. Compost produced from reactors with continuous mixing had better texture than that obtained from reactors with intermittent mixing. When moisture content was 68%, organic waste was kneaded rather than mixed in the continuous mixing reactors. Amount of organic material degraded in the continuous mixing reactors also was lower than that in the intermittent mixing reactors.

• Journal of Hydrogen and New Energy
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• v.26 no.3
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• pp.199-205
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• 2015

Organic wastes such as food waste (FW), livestock wastewater (LW), and sewage sludge (SWS) can produce hydrogen ($H_2$) by anaerobic acid fermentation. Expecially, FW which has high carbohydrate content produces $H_2$ and short chain fatty acids by indigenous $H_2$ producing microorganisms without adding inoculum, however $H_2$ production rate (HPR) and yield have to be improved to use a commercially available technology. In this study, LW was mixed to FW in different ratios (on chemical oxygen demand (COD) basis) as an auxiliary substrate. The mixture of FW and LW was pretreated at pH 2 using 6 N HCl for 12 h and then fermented at $37^{\circ}C$ for 28 h. HPR of FW, 254 mL $H_2/L/h$, was increased with the addition of LW, however, mixing ratio of LW to FW was reversely related to HPR, exhibiting HPR of 737, 733, 599, and 389 mL $H_2/L/h$ at the ratio of FW:LW=10:1, 10:2, 10:3, and 10:4 on COD basis, respectively. Maximum HPR and $H_2$ production yield of 737 $H_2/L/h$ and 1.74 mol $H_2/mol$ hexoseadded were obtained respectively at the ratio of FW:LW=10:1. Butyrate was the main organic acid produced and propionate was not detected throughout the experiment.

• Journal of the Korean Ceramic Society
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• v.39 no.6
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• pp.576-581
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• 2002

In order to simultaneously vitrify the ton Exchange Resin(IER) and Dry Active Waste(DAW) generated from the Nuclear Power Plants, a vitrification pilot test was conducted using an induction cold crucible melter. The PCT result evaluating the chemical durability of the vitrified from showed that the final glass was more durable than the benchmark glass. Liquidus temperature for the final vitrified form was 1048 K(775$\^{C}$) fur heat treatment experiments. The value of the compressive strength for the vitrified form was ninety times higher than the regulation limit, 34 kg/㎠. The glasses on bottom, middle and top of the CCM were homogeneous with no secondary phase. The precipitation of the magnetic metal phase was able to be avoided by simultaneously fEeding of DAW with IER containing strongly reducing organics. Volume reduction factor of 74 was achieved through the vitrification Pilot test for mixed waste.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.26 no.1
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• pp.21-25
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• 2014

A drying machine for discarded Citrus scrap was developed in this study. The Citrus produced in Jeju Province was treated as wastes (a) after making a beverage, such as drinking juice, and (b) if the size of the product did not fit with its agricultural product criteria. Various types of drying machine were developed in this study, and different kinds of technologies were combined improve the performance. To enhance the performance, the system was maintained in a vacuum state, and a high frequency micro wave was activated to the waste Citrus scrap, to heat up the moisture inside the Citrus kernels. The frequency of the micro-wave was 2.6 GHz, which is the resonant frequency of the molecules. Experiments were conducted with a vacuum of 50, 100, 150, 300, 500, and 700 mbar. The waste Citrus scrap has two types of status : (a) original scrap, and (b) mixed with blender. As results, specimen (a) shows a 0.13 g/sec evaporation rate, while specimen (b) shows a 0.19 g/sec rate, at 50 mbar of environment vacuum condition. For the drying efficiency, specimens (a) and (b) show 0.15 g/W and 0.24 g/W, respectively.

• Journal of the Korea Institute of Building Construction
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• v.11 no.4
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• pp.363-370
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• 2011

This study considerated reject ash, wastes of coal-fired power plants, to use mineral admixtures for cement. The pozzolan activity selected the fineness of the efficient reject ash through comparison and it compared to the fly ash that are widely used for concrete mixed material. Cement composites was prepared replacing of slag cement by fineness reject ash and fly ash, and properties of cement composites was tested by paste(setting time, fluidity, instrumental analysis) and mortar(compressive strength). Instrumental analysis results showed hydration reaction of fineness reject ash was not different from fly ash, but had more dense micro structures. Results of physical properties showed fineness reject ash shorten setting time, increased compressive strength compared by fly ash. Therefore using fineness reject ash with $6,000cm^2$/g to concrete mineral admixtures or cement composites was might be possible and could contribute to improve properties of concrete.

• Korean Journal of Crystallography
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• v.14 no.1
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• pp.1-6
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• 2003

NiZn-ferrites were synthesized from the waste catalysts. which were by product of styrene monomer process and buried underground as an industrial wastes, and their magnetic properties were investigated. Nickel oxide and zinc oxide powders were mixed with finely ground waste catalysts, and spinel type ferrite was obtained by calcination at 900℃ and sintering at 1325℃ for 5 hours. The initial permeabilities were measured and reflection losses were calculated from S-parameters for the composition of Ni/sub x/Zn/sub 1-x/Fe₂O₄(x=0.36, 0.50, 0.66) and (Ni/sub 0.5/Zn/sub 0.5)/sub 1-y/Fe/sub 2+y/O₄(y=-0.02, 0, 0.02).

• Journal of the Korea Organic Resources Recycling Association
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• v.26 no.1
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• pp.13-19
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• 2018

25 local districts in Seoul have been running Waste Transfer Stations(WTSs) to secure regional collection bases, to connect between collection systems and waste treatment systems, and to commit various pre-screening of mixed wastes. There were, however, few previous researches to define how much WTSs are beneficial to waste collection system at least in Korea. So this study analyzed costs of waste collection systems with varied haul distances from waste sources(WSs) to WTS or building types of WTSs. Major results showed that the closer WTS is to WS or the cheaper the construction cost of WTS is, the lower the cost of waste collection system is. There was an additional result that WTS system with more than 15 km of total haul distance might be useful in Seoul and encapsulation of WTS in building or underground will make effective total haul distances longer up to 35km.

• Journal of the Korean Ceramic Society
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• v.38 no.12
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• pp.1162-1166
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• 2001

NiZn-ferrite was synthesized from waste catalysts, which were produced from styrene monomer process and buried underground as an industrial wastes, and its magnetic properties were investigated. Nickel oxide and zinc oxide powders were mixed with finely ground waste catalysts, and spinel type ferrite was obtained by calcination at 900$\^{C}$ and sintering at 1230$\^{C}$ for 5 hours. The intial permeability was measured and reflection loss was calculated from S-parameters for the composition of Ni$\_$x/Zn$\_$1-x/Fe$_2$O$_4$(x=0.36, 0.50, 0.66). NiZn-ferrite synthesized from waste iron oxide catalyst showed a feasibility for the use as electromagnetic wave absorber in X-band.