• Journal of the Korean Geosynthetics Society
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• v.15 no.3
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• pp.39-47
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• 2016

In order to prevent leakage of leachate in offshore landfill, hydraulic barrier is indispensable. In the case of rubble mound revetment at offshore landfill, HDPE sheet in slope should be installed. In this study, seepage analysis were performed to evaluate seepage and flow in the seabed and revetment according to extended length of HDPE sheet by using SEEP/W. Results show that, in the case of low permeability layer is distributed where extended length of HDPE sheet was more than 1m, seepage flux in seabed and revetment was greatly reduced. In order to prevent seepage in seabed and revetment in the case of sand layer of high permeability is existed above low permeable layer, extended length of HDPE sheet and impermeable improvement width of permeable layer should be more than 1m at seabed.

• Journal of the Korean Geosynthetics Society
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• v.18 no.4
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• pp.97-106
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• 2019

This study was conducted to propose a reasonable requirement regulation of barrier system of rubble mound revetment offshore landfill for preventing contaminant leakage. The barrier is composed with bottom layer and side barrier. The bottom layer was assumed as impermeable clay layer and side barrier was composed with HDPE sheet (primary element) and mid-protection layer (supplementary element). Seepage-advection-dispersion numerical analysis has been conducted using SEEP/W and CTRAN/W programs under steady flow. As the results, the minimum required barrier regulations for hydraulic conductivity and thickness of the bottom layer were suggested. For side barrier, the extended length of HDPE sheet and the hydraulic conductivity of mid-protection layer were also suggested.

• Nuclear Engineering and Technology
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• v.33 no.2
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• pp.184-191
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• 2001

The effects of ${\gamma}$-irradiation on the crosslinking of high density polyethylene (HDPE) was investigated for the purpose of obtaining a suitable formulation for heat shrinkable materials. In this study the HDPE specimens were prepared by blending with cross linking agents and pressed into a 0.2 mm sheet at 18$0^{\circ}C$. ${\gamma}$-irradiation was conducted at 40 to 100 kGy in nitrogen. The heat shrinkable property and thermal mechanical property of the HDPE sheets have been investigated. It was found that the degree of crosslinking of the irradiated HDPE samples were increased with irradiation dose. Compared with the HDPE containing triallylisocyanurate, the HDPE containing trimethylol propane triacrylate shows a slight increase in crosslinking density. The heat transformation and dimension change of HDPE decreased with increasing radiation dose. The heat shrinkage of the samples increased with increasing annealing temperatures. The thermal resistance of HDPE increased upon the crosslinking of HDPE.

• Journal of the Korea Convergence Society
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• v.12 no.6
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• pp.33-38
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• 2021

In order to manufacture a lightweight medical radiation shielding sheet, a new shielding material was studied. We tried to verify the possibility of a shielding material by mixing egg shell powder, which is thrown away as food waste at home, with a polymer material. Existing lightweight materials satisfy eco-friendly conditions, but there are difficulties in the economics of shielding materials due to the cost of the material refining process. This study aims to solve this problem by using egg shells, which are household waste. A 3 mm-thick shielding sheet was fabricated using HDPE, a polymer material, and particle distribution within the cross-section of the shielding sheet was also verified. The shape of the particles was rough and there were voids between the particles, and the average weight per unit area was 1.5 g/cm². The shielding performance was around 20% in the low energy area and 10% in the high energy area, showing the possibility of a low-dose medical radiation shielding body.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2017.05a
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• pp.234-235
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• 2017

The bonding of the asphalt-based waterproof sheet is carried out in such a manner that the sheet and the sheet are adhered together and the lower adhesive layer of one sheet is adhered to the upper film layer of the other sheet, and the asphalt layer and the PE or HDPE film layer are bonded. When the joints are formed in the form of junctions between heterogeneous materials and exposed to the concrete joint movements and other deteriorating factors, the integrity of the joints can deteriorate and problems such as lifting and peeling off of the joints can occur. Therefore, this study was carried out to prevent unstable joint adhesion of the asphalt compound and film layer and to prevent defects in the adhesion between self - adhesive waterproof sheets. The self-adhesive waterproof sheet of this study can maximize bond stability by inducing bond between asphalt compounds during sheet-to-sheet bonding, thereby improving bonding strength.

• Journal of the Korean Geosynthetics Society
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• v.19 no.4
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• pp.1-9
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• 2020

This study analyzes contaminant movement under transient flow in a rubble mound revetment offshore waste landfill barrier system that prevents contaminant runoff. The barrier system consists of bottom layer and side barrier. For the bottom layer system, impermeable clay layer is used. For the side barrier system, the HDPE barrier sheet (primary element) plays the main role, and the intermediate protection layer (supplementary element) is responsible for the barrier. Seepage, advection, dispersion numerical analysis was carried out using SEEP / W and CTRAN / W programs. As a result, under abnormal conditions considering the fluctuation in tidal range, the volume and direction of the flow velocity vector of the pore water change with time and the dispersion concentration of the contaminant changes. When comparing the case of 2 m tidal range and 8 m tidal range, the larger the tide value, the higher the concentration of contaminant under abnormal conditions. It was found that the rate of change of the concentration of the contaminant changed depending on the change in the tidal range, and as a result, the outflow of the pollutant was smaller than that in the steady flow state.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.14 no.6
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• pp.3089-3095
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• 2013

The headliner was made of polyurethane(PU) and glass fiber(GF) composite materials are widely used as a sound insulation material. A large amount of waste materials occurs as a by-product in the headliner manufacturing process. In order to efficiently reuse the headliner waste materials, separation process of the components are very necessary. According to the results of thermal analysis, weight loss showed increase in the order polyurethane foam> non-foaming polyurethane> non-woven fabric> 1st layer> glass fiber in the range of up to $400^{\circ}C$. Analysis of the DSC characteristics, HDPE, LLDPE, PP, and Master Batch by adding additives the wasted scrap. As a result, except for the PP, there was no exothermic transition due to the crystallization.

• Journal of the Korean Institute of Landscape Architecture
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• v.29 no.1
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• pp.131-139
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• 2001

This paper aims at surveying through case studies the planting possibility on the interval artificial ground between the bank and the core landfill of the first section of works in the SUDOKWON Landfill area landfill area which was completed, followed by the layer-on-layer landfill process involving the latch or sealing layer against emitting landfill gas from the reclaimed waste. The survey results are as follows; 1. The layers of the artificial planting ground on the landfill were established on the basis of top-on-top procedure for a waste layer, a topping soil layer (T=50cm), a gas blocking layer (broken stones T=30cm), a filter layer (non-woven fabric 700g), a sheet protecting soil layer (T=20cm), and a blocking layer (HDPE SHEET 2.0mm), an irrigation layer (SAND T=30cm), a filter layer (non-woven fabric 700g), a sheet protecting soil layer (T=20cm), and a blocking layer (HDPE SHEET 2.0mm), an irrigation layer (SAND T=30cm), a filter layer (non-woven fabric 700g), a planting layer (T=90cm+), a top mound (T=2m). 2. Since no direct damage on the planting layer affected by the landfill gas was detected, planting is found to be still possible and successful except the severely unequal subsidence portion. 3. The mortality rate is discovered different on different trees: Pinus thunbergii (H3.0$\times$W1.0m) 11.25%, Pinus thunbergii (H2.5$\times$W0.8m) 4.73%, Koelreuteira paniculata 8.67%, Hibiscus syriacus 5.68%, Deutzia parviflora 6.50%, Forsythia koreana 8.17%, Rho. yedoense v. poukhanese 32.22%, and Spiraea pru v. symplicifolia 18.89%; although the last two of which are generally considered to have a strong generic growing character, they are subject to be weakened when exposed to the contaminated microclimate of the site like landfill gas. 4. The damage rates, on Pinus thunbergii, Koelreuteria paniculata, Hibiscus syracus, Forsythia koreana, Deutzia parviflora, Rho. yedoense v. poukhanense were shown to decrease to 7.31-17.69% in the second check (June 2000) lower than 5.77-46.92% in the first examination (June 1999), whereas the damage on Spiraea pru v. symplicifolia relatively increased. It is believed that preparatory method of the air pollution, change of temperature, odor by emitting landfill gas, and minute dust from vehicles should be made, and a research on this matter will be conducted in the near future.

• Journal of the Korea Institute of Military Science and Technology
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• v.17 no.1
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• pp.129-134
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• 2014

We have developed a cost-effective and facile method to manufacture a pouch-type chemical vapor sampler. Originally, the sampler was developed by U. S. Army Natick Soldier Research, Development, and Engineering Center(NSRDEC) to determine the protective capability of individual protective ensembles or Man-in-Simulant Test (MIST). They used a selectively permeable high density polyethylene(HDPE) as front membrane and aluminum/ Nylon barrier film as an impermeable back sheet in order to mimic the actual adsorption process that occurs when the skin is exposed to chemical weapons. However, it costs over twenty dollars per sampler and the minimum of quantity is 2500 per order. In addition, it is inconvenient to employ a variety of adsorbents into the sampler, which could prevent MIST researchers to do various tests for development of MIST methodologies. Here, we report the simple method to manufacture the sampler in a laboratory scale. All the materials we used are easily obtainable and inexpensive. In addition, all the procedures we perform are generally known. We used methyl salicylate(MeS) vapor to be adsorbed into the sampler and employed several different adsorbents to evaluate the performance of samplers. The results obtained by home-made samplers and commercially avaliable one showed no significant differences. Also, MeS vapor was selectively adsorbed into the sampler depending on adsorbents. We conclude that home-made samplers are capable of collecting any kind of chemical vapor for a variety of purposes.

• Journal of Soil and Groundwater Environment
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• v.14 no.4
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• pp.15-22
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• 2009

The remediation efficiency for a large scale petroleum-contaminated site was evaluated by using the Engineered Land-farming system which was consists of the following parameters; moisture & nutrient injector data, blower system, HDPE sheet and sump system. To enhance the degradation ability in the early stage, main nutrients such as nitrogen (N) and phosphorus (P) were adjusted for the site condition. As a result of the periodic tilling process, the concentration of contaminated soil was decreased to 348 mg/kg, which was lower than 500 mg/kg (regal standards) while satisfying remediation Efficiency of 82% (the maximum concentration of 1,893 mg/kg). The appropriate temperature range for an active operation was investigated between $28.9{\sim}35.6^{\circ}C$. For the contaminated soils having different initial concentration, the TPH (Total Petroleum Hydrocarbons) concentration was decreased evenly along with the CFU (Colony Forming Unit), moisture content and contaminant concentration after 38days of gratifying the legal standards of under 500 mg/kg.