• 한국해양공학회:학술대회논문집
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• 한국해양공학회 2002년도 추계학술대회 논문집
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• pp.354-358
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• 2002

This paper describes the need for a ductile Fiber Reinforced Plastics (FRP) reinforcement for concrete structures. To promte the degradation of the adhesive condition at the fiber/matrix micro interface without matrix dissolution loss were carried out in salt water surrounding. The absorption properties and the bending strength were compared about GFRP rebar and steel bar.

• 공업화학
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• 제34권4호
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• pp.421-425
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• 2023

Polymethyl methacrylate (PMMA), polycarbonate (PC), polyvinyl chloride (PVC), 그리고 polyacetal을 포함하는 일부 플라스틱류에 대한 연기특성을 조사하였다. 연기밀도는 ISO 5659-2의 기준에 의해 연기밀도시험기를 이용하여 정적인 연기 특성의 관련 값을 측정하였다. 또한 불꽃을 동반하는 연소와 불꽃을 동반하지 않는 연소를 구분하여 측정하였다. 불꽃방식의 복사열 50 kW/m² 의 조건하에서 연기의 최대비광학밀도(D_m) 측정값은 PMMA (401.26)가 최저로, PVC (1345.04)가 최대로 나타났다. 또한 비불꽃방식의 복사열 50 kW/m² 의 조건하에서 연기의 D_m 측정값은 PMMA (262.82) 가 최저로, PVC (1385.43)가 최대로 나타났다. 대상물의 연소 시 연기발생은 복사열 유속의 영향을 상당히 받으며, 탄화성 플라스틱은 연소 시 비탄화성 플라스틱보다 높은 연기 발생량을 나타내었다. 주 고분자 사슬에 방향족 그룹이 있는 폴리머는 열분해로 인해 다량의 숯이 생성되므로 다량의 연기를 발생시켰다.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2005년도 춘계학술대회 논문집
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• pp.430-433
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• 2005

Laser bonding between similar and dissimilar thermoplastics has been investigated by making use of laser transmission weld technique. Spot welding of two layers of plastic materials has been demonstrated by using of a high-quality diode-laser with 808nm wavelength. Weld areas increases according to power density, exposure time. The results of peel out test show that peel strengths increase with the area of molten plastics. Layers, which have the same chemical properties, have good bonding qualities. A bonding method which dye film is coated on the interface is used for laser bonding between plastics with high transmission for laser wavelength. Laser transmission bonding is worthy of attention because it is not in contact, requires a few tooling devices, allows a flexible energy delivery and produces nearly invisible welds

• Journal of Korean Society for Atmospheric Environment
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• 제11권E호
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• pp.13-21
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• 1995

This Pilot study identifies potential dioxin and furan sources and medical plastic wastes produced from hospital solid waste streams. In this study, air emissions of dioxins and furans from sources in the U.S., which were estimated by the U.S. Environmental Protection Agency (EPA), were summarized. Potential loading routes of dioxins and furans to the U.S.-Canada Great Lakes region have also been identified in trcent surveys. In addition, medical and hospital solid wastes produced in typical large city hospitals were characterized as important potential sources of dioxins and furans. Plastic contents in medical Plastics Characterization Survey (MMPCS), plastics composition data were obtained from a survey of five Massachusetts Hospitals and Medical Centers. By identifying plastic wastes as a percentage of total hospital wastes, we were able to use data from a preliminary study that analyzed the waste stream of 16 major New York City hospitals (NYCMWS) characterizing the plastic content of the wasters. This study determined the types of plastic wastes included in each medical waste stream (regulated medical waste or non regulated medical waste) and it discussed the potential for recyclibility of hospital plastic wastes. The combination of the NYCMWS and the MMPCS surveys provides for the first overview of the size of the recycling task of hospital plastic wastes and the potential of dioxin elimination if dioxin generating plastics were to be eliminated from hospital use.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2003년도 춘계학술대회 논문집
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• pp.1354-1357
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• 2003

Mold Analysis is crucial factors in the design of injection molding process. Since the qualify of products depends on filing, shrinkage and etc, the procedure of prediction through analysis in the design of injection molding process is needed. In many cases, this kind of analysis makes it possible to predict pressure pattern which determines the condition of injection molding process. Crystallinity is the factor that determines the shrinkage of products. The studies showed the factors that had been related to the degree of crystallinity, which were mostly Weight Reduction, mold temperature and melt temperature. Therefore, the objective of this study is to see the differences of the degree of crystallinity depending on the positions of foamed plastics. The procedure of this study is as the following. First, Simulate the pressure gradient in mold cavity that can produces specimen by using Moldflow. Secondly, produce specimen and measure the degree or crystallinity of each part of specimen by using XRD. Lastly, identify the sensitivity of conventional plastic and foamed plastic on pressure gradient by comparing the simulation and the results of measurement.

• 한국정밀공학회지
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• 제26권6호
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• pp.42-49
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• 2009

The optical elements made of plastics are normally produced by mass production such as injection molding with use of precision dies and molds. It costs to prepare the dies and molds, and it is only justified to prepare such expensive dies and molds when the parts are massively produced. On the other hand, it is too expensive and inefficient when precision plastic parts are needed only in small quantities, such as a case of trial manufacturing of new products. An ultra-precision diamond cutting is one of promising processes to produce the precision plastic parts in such cases. But it is commonly believed that an ultra-precision cutting of plastics for optical components is very difficult, because they are thermo-plastic material. In the present research, an ultra-precision diamond cutting of polycarbonate (PC), that is one of typical optical materials, was tried by using elliptical vibration cutting method. It is experimentally proved that good optical surfaces were obtained by using elliptical vibration cutting in cases of grooving and flat surfaces. The maximum surface roughness of less than 60 nm in peak to valley value is acquired.

• 한국정밀공학회지
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• 제23권8호
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• pp.195-202
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• 2006

High-speed machining (HSM) with excellent quality and dimensional accuracy has been widely used to create 3D structures of metal and plastics. However, the high-speed machining process is not suitable for the rapid realization of 3D thin-walled product because it consumes considerably long time in fixturing process of a work piece. In this paper, an effective rapid manufacturing process is proposed to fabricate 3D thin-walled products directly using HSM, phase change filling and ultrasonic welding. The filling process is useful to hold the thin-walled product during the machining step. The ultrasonic welding process is introduced to make one piece product from two piece parts that are machined by HSM and filling process. The proposed rapid manufacturing (RM) process has been shown that the RM process enables to fabricate the 3D thin-walled products using ABS plastics and aluminum metals from 3D CAD data to functional parts.

• 청정기술
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• 제25권4호
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• pp.289-295
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• 2019

비닐, 플라스틱의 사용이 전 세계에서 지속적으로 증가하고 있으나, 세계 각국의 폐비닐 또는 폐플라스틱의 처리를 위한 수입이 금지됨에 따라 자국 내의 친환경적 처리 또는 이용이 요구되고 있다. 폐비닐, 폐플라스틱의 친환경적인 처리에 대한 수요가 점차 증가하고 있으나, 폐비닐에 묻어 있는 이물질로 인하여 환경친화적인 재활용 방법이 제한되고 있다. 또한 기존의 매립, 소각 방법은 2차 오염의 발생과 처리 비용의 증가를 야기시키고 있다. 따라서 폐비닐에 포함되어 있는 타재질 및 이물질의 선별 제거는 폐비닐의 고부가가치 재활용을 가능케 할 수 있다. 특히 파쇄/선별이 단일 기기에서 동시에 이루어지는 신공정은 자원 재활용을 극대화시킨다. 본 연구는 파쇄/선별 융합 공정을 통해 이루어지는 폐비닐의 분리, 열적 재활용, 물질 재활용의 기술경제성을 평가하였다. 특히 국내 환경 정책에 따른 다양한 지원금들의 변화가 미치는 영향을 고찰하였다. 재활용 인센티브의 가격과 소각에 참여하는 폐비닐의 수율에 따라서 순현재가치와 내부수익률이 크게 변동되었다.

• Design & Manufacturing
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• 제9권1호
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• pp.23-26
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• 2015

For mass production of plastics, injection molds have multi-cavities. However, filling imbalance between cavity to cavity always has occurred in multi-cavities mold, and this has caused low quality of plastics part. In this study, the closed-loop-control system which can control temperature of hot manifold and nozzle in hot runner mold for filling balance has been suggested, and a series of experiment about difference of filling time and weight in cavity-to-cavity was conducted. As a result of using closed-loop-control system, a remarkable improvement in reducing filling imbalance was confirmed.

• International Journal of Automotive Technology
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• 제4권4호
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• pp.203-211
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• 2003

This paper describes a method for a falling weight impact test to estimate the impact energy absorbing characteristics and impact strength of CFRP (Carbon-fiber reinforced plastics) laminate plates based on considerations of stress wave propagation theory, which were converted to measurements of load and displacement verses time. The delamination area of impacted specimens for the different ply orientations was measured with an ultrasonic C-scanner to determine the correlation between impact energy and delamination area. The energy absorbed by a quasi-isotropic specimen having four interfaces was higher than that of orthotropic laminates with two interfaces. The more interfaces, the greater the energy absorbed. The absorbed energy of a hybrid specimen embedding GFRP (Glass-fiber reinforced plastics) layer was higher than that of normal specimens. Also, a falling weight impact tester was built to evaluate the characteristics and impact strength of CFRPs.