• 한국정밀공학회:학술대회논문집
• /
• 한국정밀공학회 2004년도 추계학술대회 논문집
• /
• pp.1414-1417
• /
• 2004

A thick-layered RP process, transfer-type variable lamination manufacturing using expandable polystyrene foam (VLMST) has been developed to have the advantageous characteristics such as high building speed, low cost for introduction and maintenance of VLM-ST apparatus, and little staircase surface irregularities of parts. However, VLM-ST has difficulty fabricating an axisymmetric shape and a large-sized freeform shape because of the limited sloping angles and small build size. The objective of this paper is to develop a multi-functional hotwire cutting system using EPS-foam (MHC). MHC employs a four-axis synchronized hotwire cutter with the structure of two XY movable heads and a turntable. In order to examine the applicability of the developed MHC apparatus, an axisymmetric shape, a polyhedral shape and a large-sized freeform shape were fabricated on the apparatus.

• 한국정밀공학회:학술대회논문집
• /
• 한국정밀공학회 2000년도 추계학술대회 논문집
• /
• pp.763-766
• /
• 2000

Rapid Prototyping(RP) techniques have their unique characteristics according to the working principles: stair-stepped surface of parts due to layer-by-layer stackin, 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 RP apparatus. The objective of this study is to develop software for automatic generation of unit shape part (USP) for a new RP process, Variable Lamination Manufacturing using linear hotwire cutting technique and expandable polystyrene foam sheet as part material (VLM-S). In order to examine the applicability of the developed software to VLM-S, USP's of general three-dimensional shapes, such as an auto-shift lever knob and a pyramid shape were generated.

• 한국화재소방학회:학술대회논문집
• /
• 한국화재소방학회 2010년도 춘계학술논문발표회 논문집
• /
• pp.383-388
• /
• 2010

1999년 씨랜드 청소년 수련원 화재로 19명이 사망하여 샌드위치 패널의 위험성이 대두되었으며, 2008년도 이천 냉동창고 화재 그리고 최근 2009년 11월 19일에도 샌드위치 패널로 건축된 물류창고에서 화재가 발생하였다. 이러한 샌드위치 패널로 시공된 물류창고 등의 화재는 확대가 빠르므로 난연재 소재의 샌드위치 패널의 필요성에 대한 관심이 높아져 가고 있다. 따라서 본 연구에서는 폴리스티렌 폼을 심재로 한 샌드위치 패널의 장점에 난연성을 부과하여 화재 안전성을 도출하는 하고자 한다. 샌드위치 패널의 심재로 주로 사용되어지는 EPS 비드에 저가의 물유리를 코팅하여 난연성을 도출하고자 한다. 2차 발포 성형시에 물유리가 고온의 스팀에 씻겨 내려가지 않고 남아서 난연성을 나타내도록 하는 것이 목표이다.

• 한국건설순환자원학회논문집
• /
• 제3권4호
• /
• pp.328-334
• /
• 2015

건축용 단열재는 에너지 절약을 목적으로 적용되며 불연 및 내화성능이 요구되는 부위는 무기계 섬유를 주재료로 사용하는 미네랄울 및 글라스울 소재가 적용된다. 하지만 무기계 소재인 미네랄울이나 글라스울은 특성상 수분에 취약하여 뭉침 및 처짐 현상 등이 발생하여 단열효과가 떨어지며 유기계 소재인 폴리스티렌폼이나 우레탄폼 등은 화재에 취약하고 일산화탄소 발생에 의한 가스유해성 등으로 적용에 한계를 갖고 있다. 본 연구에서는 폐유리분말과 플라이애시를 사용하여 가볍고 열전도율이 낮은 무기계 경량 발포소재를 제조하고 물리적 특성을 분석하여 단열용 제품으로서의 가능성을 확인하고자 하였다. 연구결과 폐유리분말과 플라이애시를 사용한 경량 발포소재는 균일한 공극을 형성하며 발포하였고 경량이며 불연재료이므로 불연성능 요구되는 부위에 사용이 가능하다.

• Journal of the Korean Wood Science and Technology
• /
• 제45권3호
• /
• pp.360-367
• /
• 2017

본 연구에서는 단열성능 및 물리적 성질이 우수한 친환경 목섬유 단열재의 제조 기술을 확립하기 위하여 멜라민 요소 폼알데하이드(MUF), 페놀 폼알데하이드(PF), emulsified MDI (eMDI) 및 라텍스계 수지 등 서로 다른 접착제로 제조한 저밀도섬유판의 특성을 비교하였다. 그 결과 MUF, PF, eMDI 수지 접착제로부터는 경질(硬質) 저밀도섬유판이, 라텍스계 수지 접착제로부터는 연질(軟質)의 저밀도섬유판이 각각 제조되었다. 모든 저밀도섬유판은 일반 중밀도섬유판에 비해 현저히 낮은 열전도율을 나타냈으며, 압출 발포 폴리스티렌과 유사한 단열 성능을 나타내는 것으로 조사되었다. 한편 본 연구에서 제조한 저밀도섬유판 중 eMDI를 사용한 것은 흡수 두께/길이 팽창률 및 휨 강도 등 물리적 성질이 가장 우수하였다.

• 한국소성가공학회:학술대회논문집
• /
• 한국소성가공학회 2001년도 추계학술대회 논문집
• /
• pp.190-194
• /
• 2001

The integration of rapid prototyping and tooling has the potential for the rapid net shape manufacturing of three-dimensional parts with geometrical complexity. In this study, a new rapid prototyping process, transfer type of Variable Lamination Manufacturing (VLM-ST), was proposed to manufacture net shape of 3-D prototypes. In order to examine the efficiency and applicability of the proposed process, various 3-D parts, such as a world-cup logo, and extruded cross and a knob shape, were fabricated on the apparatus. In addition, the new rapid tooling process, which is a triple reverse process, was proposed to manufacture of 3-D functional part using VLM-ST prototypes and the plastic part of the knob shape was produced by the new rapid tooling process.

• 한국정밀공학회지
• /
• 제22권4호
• /
• pp.194-202
• /
• 2005

The objective of this paper is to develop a multi-functional hotwire cutting system (MHC) using EPS-foam block or plate as the working material. Because the MHC apparatus employs a four-axis synchronized hotwire cutter with the structure of two XY movable heads and a turntable, it allows the easy fabrication of various 3D shapes, such as (1) an axisymmetric shape or a sweeping cross-sectioned pillar shape using the hot-strip in the form of sweeping surface and EPS foam block on the turntable, (2) a polyhedral complex shape using the hotwire and EPS foam block on the turntable, and (3) a ruled surface approximated freeform shape using the hotwire and EPS foam plate. In order to examine the applicability of the developed MHC apparatus, an axisymmetric shape, a polyhedral shape and a large-sized freeform shape were fabricated on the apparatus.

• 한국정밀공학회:학술대회논문집
• /
• 한국정밀공학회 2002년도 춘계학술대회 논문집
• /
• pp.947-951
• /
• 2002

During the hotwire cutting of EPS foam sheet, the dimensional accuracy and part quality of the cut par are highly dependent upon the thermal field in the EPS. The thermal field is determined by operating parameters such as heat input, cutting speed and cutting angle. The objective of this study is to investigate into the influence of cutting angle on the kerfwidth and part quality of the cut part in hotwire cutting of EPS foam using the experiments and the numerical analysis in the case of a single sloped cutting. In order to estimate an accurate temperature field, the transient thermal analysis using a moving coordinate system and the sloped heat flux model is carried out. From the results of the experiments and the analysis, it has been found that the effect of cutting angle on the kerfwidth and the melted area at the edge are 0.1 mm and 0.11 m$m^2$ respectively. The results of the experiments show that the surface roughness is not appreciably influenced by the cutting angle.

• 한국정밀공학회지
• /
• 제18권8호
• /
• pp.64-70
• /
• 2001

In all the Rapid Prototyping (RP) techniques, the computer-aided design (CAD) model of a three-dimensional part is sliced into horizontal layers of uniform, but not necessarily constant, thickness in the building direction. Each cross- sectional layer is successively deposited and, at the same time, bonded onto the previous layer. The stacked layers form a physical part of the model. The objective of this study is to develop a software for automatic generation of unit shape part(USP) for a new RP process, Variable Lamination Manufacturing using the linear hotwire cutting technique and expandable polystyrene foam sheet as part material(VLM-S). In order to examine the applicability of the developed software to VLM-S, USPs of general three-dimensional shapes, such as an auto-shift lever knob and a pyramid shape were generated.

• 한국정밀공학회:학술대회논문집
• /
• 한국정밀공학회 2002년도 추계학술대회 논문집
• /
• pp.176-180
• /
• 2002

All types of VLM-s process include the linear heat cutting of EPS foam to generate a layer with 3D shape. The dimensional accuracy and part quality of the cut part are dependent on the thermal characteristics in the EPS foam. The thermal characteristics are determined by operating parameters such as an effective heat input and cutting angle. The objective of this study is to investigate into the influence of cutting angle on the kerfwidth and the melted length of the cut part using the numerical analysis and the experiments in generally sloped cutting with two cutting angles. In order to estimate an accurate temperature field, the transient thermal analysis using moving coordinate system, the fully conformed mesh and the heat flux model with two cutting angles is carried out. From the results of the analysis and the experiments, it has been found that the influence of the rotational angle about x-axis in which the rotational axis is normal with hotwire cutting direction is appreciably negligible in comparison with that of the rotational angle about y-axis.