• Proceedings of the Korean Society of Precision Engineering Conference
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• 2001.04a
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• pp.910-913
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• 2001

Rapid Prototyping(RP) techniques have unique characteristics according to their working principle: the stair-stepped surface of a part due to layer-by-layer stacking, low building speed, and additional post-processing to improve surface roughness. A new RP process, Variable Lamination Manufacturing by using expandable polystyrene foam(VLM-S), has been developed to overcome the unfavorable characteristics. The objective of this study is to investigate the thermal characteristics and skeleton size effects as the hotwire cuts EPS foam sheet in order to improve dimensional accuracy of the parts, which is produced by VLM-S. Empirical and analytical approaches are performed to find the relationship between cutting speed and heat input, and the relationship between maximum available cutting speed and heat input. In addition, empirical approaches are carried out to find the relationship between cutting error and skeleton size, and cutting deviation and skeleton size. Based on these results, the optimal hotwire cutting condition and available minimum skeleton size are derived. The outcomes of this study are reflecting in the enhancement of VLM-S input data generation S/W.

• Fire Science and Engineering
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• v.16 no.4
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• pp.77-84
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• 2002

In this paper, we had analyzed comsbustion gases using a GASTEC colorimetric gas detector tube according to the method of NES 713 in order to combustion gases toxicity evaluation for beads polystyrene foam, extruded polystyrene foam, rigid polyurethane foam, flexible polyurethane foam, flexible polyvinyl chloride pipe, vinyl floor cover, polyethyelene foam(flame retardant untreated) and polyethyelene foam (flame retardant treated) of plastics material. As results of gas analyses by using this method, comsbustion gases producted from small specimens of plastics material had reached fatal to man at 30 minutes exposure time that had possesed toxicity index of more than 1. Toxicity indexes of each specimen were estimated range of 4.3∼179.2, flexible polyvinyl chloride showed the hightest toxicity index at 179.2, and beads polystyrene foams showed the lowest toxicity index at 4.3.

• Journal of the Korea Concrete Institute
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• v.13 no.1
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• pp.30-37
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• 2001

Generally, polymer mortar made with unsaturated polyester(UP) resin has a high curing shrinkage. This is an inadequate as repair material and construction products that have been widely used for years recently. To overcome these problems, polymer researchers and engineers have used shrinkage-reducing additives, which are usually specific thermoplastic polymers. The objective of this study is to evaluate the effects of shrinkage-reducing additive on the curing shrinkage and strengths of UP mortar. UP mortars are prepared with expanded polystyrene(EPS) ratio in styrene monomer(SM), (EPS/PS, PS=EPS+SM), and the ratio of total polystyrene resin(PS) to UP resin, (PS/UP). And it is tested for viscosity of UP resin, slump-flow, working life, flexural and compressive strengths, and curing shrinkage tests. From the test results, viscosity of resin for UP mortar increases with increasing PS content. Curing shrinkage of UP mortar is considerably smaller than that of plain UP mortar, nevertheless, reduction in the strengths is not recognized according to adding PS resin. In this study, we can obtain the optimum mix proportions of UP mortar using PS resin which made of waste expanded polystyrene.

• Polymer(Korea)
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• v.32 no.2
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• pp.183-188
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• 2008

Reinforced open cell micro structured foams were prepared by the polymerization of high internal phase emulsions incorporating inorganic thickeners. Organoclays were used as oil phase thickener, and sodium montmorillonite was used as aqueous phase thickener. Rheological properties of emulsions increased as oil phase thickener concentration and agitation speed increased, due to the reduced drop size reflecting both competition between continuous and dispersed phase viscosities and increase of shear force. Drop size variation with thickener concentration could be explained by a dimensional analysis between capillary number and viscosity ratio. Upon the foams polymerized by the emulsions, compression properties, such as crush strength and Young's modulus were measured and compared. Among the microcellular foams, the foam incorporated with an organoclay having reactive group showed outstanding properties. It is speculated that the exfoliated silicate layers inside polystyrene matrix, resulting in nanocomposite foam, are the main reason why this foam has enhanced properties.

• Proceedings of the Korea Concrete Institute Conference
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• 2006.05b
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• pp.301-304
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• 2006

The purpose of this study is to evaluate bonding properties of PMMA mortars using EPS with silane coupling agent. PMMA mortars are prepared with various silane coupling agent, and tested for flexural strength test, adhesion test in flexure and tensile strength in underwater and air. It is estimated that the application of silane coupling agent to PMMA mortar is more effective in underwater than air.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2018.11a
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• pp.111-113
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• 2018

국제항로표지협회에서는 일정 규모이상의 해양의 양식장에는 (등)부표를 의무적으로 설치할 것을 권고하고 있다. 현재 사용되는 철제와 프라스틱 부표는 제작비용이 너무 고가로서 자발적인 설치가 어려운 실정이다. 그러므로 기존 부표보다 훨씬 저렴하면서도, 친환경적이면서도 내구성이나 기능이 뛰어난 부표를 개발하여 어민들에게 보급할 필요가 있다. 본 연구에서는 가벼우면서도 견고한 EPS(발포폴리스티렌, 고밀도 스티로폼)를 내부재료로 사용하고, 외부에 폴리우레아를 충분한 두께로 도포한 등부표에 관한 연구를 하였다.

• Journal of the Korean Recycled Construction Resources Institute
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• v.3 no.4
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• pp.328-334
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• 2015

Building insulation materials use for the purpose of energy saving. Insulation materials can be classified inorganic and organic insulation materials. Inorganic insulation is used for fire resistive performance parts and organic insulation is used for thermal performance parts. Meanwhile, organic insulation is due to toxic gas emission in fire. Inorganic insulation is too heavy and low thermal performance than organic materials. This study is focused on evaluation of the physical properties of inorganic foam material using industrial by-products such as waste glass powder and fly ash. From the test result, inorganic foam materials for the applicability of fire-resistance and insulation light-weight materials.

• Journal of the Korean Society for Precision Engineering
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• v.17 no.12
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• pp.185-194
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• 2000

Rapid Prototyping(RP) techniques have their unique characteristics according to the working principles: stair-stepped surface of parts due to layer-by-layer stacking, low build speed caused by line-by-line solidification to build one layer, and additional post processing to improve surface roughness, so it is required very high cost to introduce and to maintain of RP apparatus. The objective of this study is to develop a new RP process, Variable Lamination Manufacturing using linear hotwire cutting technique and expandable polystyrene foam sheet as part material(VLM-S), and to investigate characteristics of part material, cutting characteristics by using linear hotwire cutting system and bonding. Experiments were carried out to investigate mechanical properties of part material such as anisotropy and directional tensile strength. In order to obtain optimal dimensional accuracy, surface roughness, and reduced cutting time, addition experiments were performed to find the relationship between cutting speed and cutting offset of hotwire, and heat generation of hotwire per unit length. So, adhesion strength tests according to ASTM test procedure showed that delamination did not occur at bonded area. Based on the data, a clover-shape was fabricated using unit shape part(USP) it is generated hotwire cutting. The results of present study have been reflected on the enhancement of the VLM-S process and apparatus.

• Journal of the Korean Society for Precision Engineering
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• v.18 no.8
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• pp.54-63
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• 2001

Rapid Prototyping(RP) techniques have their unique characteristics according to the working principles: stair-stepped surface of a part due to layer-by-layer stacking, low build speed caused by point-by-point or line-by-line solidification to build one layer, and additional posts processing to improve surface roughness, so high cost is required to introduce and to maintain the RP apparatus. The objective of this study is to develop a new RP process, Variable Lamination Manufacturing by using expandable polystyrene foam sheet as part material(VLM-S), and to design an apparatus for implementation of the process. So, the process parameters and design criterions of the apparatus were defined and the techniques were proposed to satisfy the design criterion. Based on the results, a knob-shape, pyramid shape. and a solid block were fabricated on the apparatus in which unit shape part(USP) was generated for building each layer.

• Journal of the Korea Institute of Building Construction
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• v.9 no.6
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• pp.121-129
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• 2009

The construction sites of small and medium buildings have small scale groundwork and the depth of excavation is often shallow. In this case, if the groundwork, girders, and ground slabs are built simultaneously by embedded assisting form rather than the existing conventional method to place concrete twice using the general form, we can expect to reduce the frame duration of the basement, resulting in cost savings. The existing embedded assisting form is restricted from use because there are cost problems with materials, labor costs,and with quality depending on the form's type. Therefore, this study is to provide an improved suggestion of building the groundwork, girders, and ground slabs simultaneously with Polystyrene by using the embedded assisting form. It also will compare the technique with existing methods of construction, and will verify its usefulness by evaluating each method of construction.