• 한국윤활학회:학술대회논문집
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• 한국윤활학회 1999년도 제30회 추계학술대회
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• pp.257-262
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• 1999

The economic loss arisen from the abrasion wear have been increasing at every industrial field. To reduce the economic loss we developed a new process, which is named MAHa process(Metallic Adhesives for HArdening). MAHa process is a process to weld tungsten carbide(WC) to the surface of a plain carbon steel so that it may stay longer under the severe abrasive environment. The depth of the WC layer ranges from 0.5 mm to 5 m. Compared with the conventional technology, arc-augmented welding which bonds WC on the flat surface only, MAHa process has the merits that it can make a robust WC layer on the round or wave- shaped surface also. How to turn the WC powder into a flexible mat is the key technology of the MAHa process. We invented new polymer materials to accomplish such a goal and both the MAHa process and the invented materials were applied for patents. For the application, the inner wall of elbow of Concrete Pump Truck(CPT) was maharized(MAHa process-treated) and the new WC layer on the inner wall was made successfully. The elbow was equipped to a CPT.

• Journal of Welding and Joining
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• 제24권2호
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• pp.57-63
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• 2006

In this study, the curing kinetics and thermal degradation of underfill were investigated using differential scanning calorimetry (DSC) and thermo gravimetry analysis (TGA). The mechanical and thermal properties of underfill were characterized using dynamic mechanical analysis (DMA) and thermo-mechanical analysis (TMA). Also, we presented on underfill dispensing process using Prostar tool. The non-isothermal DSC scans at various heating rates, the exothermic reaction peak became narrower with increasing the heating rate. The thermal degradation of underfill was composed of two processes, which involved chemical reactions between the degrading polymer and oxygen from the air atmosphere. The results of fluidity phenomena were simulated using Star CD program, the fluidity of the underfills with lower viscosity was faster.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2005년도 춘계 학술기술논문발표대회 논문집
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• pp.223-226
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• 2005

In this study on the appliable Asphalt sheet of monolithic and inorganic matter waterproofing ,Fing material using of field because of problem of complex waterproofing sheet. Before this cement polymer modified waterproof coating and appliable asphalt sheet of monolithic whether have stability by method of construction about all style waterproofing that evaluate to new method of construction development naturally big emphasis put and try to approach. Did performance test item first at, as a result, drew by suitable thing in all KS items. This is considered to have more effective spot construction work because if means that have stability by material as well as method of construction.

• 한국정밀공학회지
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• 제28권5호
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• pp.578-584
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• 2011

In mechanical cutting process, burr was generated at workpiece by cutting tool generally. It is working disturbance during manufacturing process. Besides burr was taken shape relatively large size more micro scale machining than macro scale machining. Many researches have been studied to remove micro burr(de-burring), because it was negative effect for accuracy of machining shape. However, micro de-burring was constrained by burr height, micro feature and so on. In this paper, experimental research was carried out to compare de-burring characteristics of $Al_2O_3$ abrasive and polymer.

• 한국레이저가공학회지
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• 제18권4호
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• pp.6-11
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• 2015

Specially designed and 3D printed samples were prepared and joined by a diode laser source. To increase the strength of joining and reliability of samples, the surface was patterned by using a 3D printer. The joining surface was prepared as hemispherical shape with no-patterns, 0.5mm pitch, 0.75mm pitch and 1mm pitch. The optical properties of samples were measured by using an integrated sphere where classical Kubelka-Munk theory and modified Richard-Mudgetts theory for the analysis applied. Scanning speed was set at 500mm/min and laser power was varied between 9 and 10watts for the preliminary joining characteristic analysis.

• 대한용접접합학회:학술대회논문집
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• 대한용접접합학회 2005년도 춘계학술발표대회 개요집
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• pp.43-45
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• 2005

A precise bonding technique, transmission laser bonding using energy transfer, for polymer micro devices is presented. The irradiated IR laser beam passes through the transparent part and absorbed on the opaque part. The absorbed energy is converted to heat and bonding takes place. In order to optimize the bonding quality, the temperature profile on the interface must be obtained. Using optical measurements of the both plates, the absorbed energy can be calculated and heat transfer model was applied for obtaining the transient temperature profile. The transmission laser bonding has a potential in the local precise bonding in MEMS or Lab-on-a-chip.

• Journal of Welding and Joining
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• 제32권4호
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• pp.20-25
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• 2014

Laser heat source was applied on 3D poly urethane model built by 3D printer and cellulous acetate for joining. A diode laser with 808nm wavelength was transmitted through the 3D model and applied on the boundary of ABS/Acetate and 3D poly urethane model. Based on the experimental result, the ABS and 3D built poly-urethane polymers was successfully joined, but the mechanical strength was not enough at the joining boundaries in the range of 6watt to 8watt of laser heat source. However, biodegradable acetate was successfully joined without damaging the 3D built model and mechanical strength was properly achieved. The optimum laser power was found between 5watt and 8watt with scanning speed of 500mm/min, 700mm/min and 1,000mm/min. Based on the SEM analysis the filling mechanism was that the applied pressure on 3D built model squeezed the fluidic thermoplastics, ABS and acetate, into the structure of 3D model. Therefore soundness of joining was strongly depending on the viscosity of thermoplastics in polymers. The developed laser process is expected to increase productivity and minimize the cost for the final products.

• 한국공작기계학회:학술대회논문집
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• 한국공작기계학회 2004년도 춘계학술대회 논문집
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• pp.76-81
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• 2004

Injection molding is the most widely used process fir the industrial forming of plastic articles. During an injection molding process of composites, the fiber-matrix separation and fiber orientation are caused by the flow of molten polymer/fiber mixture. As a result. the product tends to be nonhomogeneous and anisotropic. Hence, it is very important to clarify the relations between separation orientation and injection molding conditions. So far, there is no research on the measurement of fiber orientation using image processing. In this study, the effects of fiber content ratio and molding condition on the fiber orientation-angle distributions are studied experientially. Using the image processing method, the fiber orientation distribution of welding pars in injection-molded products is assessed. And the effects of fiber content and injection mold shapes on the fiber orientation in case of fiber reinforced polymeric composites are studied experimentally.

• Journal of Welding and Joining
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• 제33권2호
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• pp.78-84
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• 2015

Self-piercing rivet(SPR) is mechanical joining methods and which can be joining dissimilar materials. Unlike conventional riveting, SPR also needs no pre-drilled holes. During plastically deformation, SPR pierces upper sheet and joins it to under sheet. SPR has been mainly applied to the joining the automobile body and some materials, such as glass fiber reinforced polymer and aluminum alloy, which represent the sheet-formed materials for lightweight automobile. Glass fiber reinforced plastic(GFRP) has been considered as a partial application of the automobile body which is lighter than steels and stronger than aluminium alloys. It is needed SPR to join Al alloy sheets and GFRP ones. In this paper, in order to design the rivet and anvil, which are suitable for GFRP, the joinability was examined through simulations of SPR joining between GFRP and Al alloy sheets. For this study, AutoCAD was used for the modeling and the simulated using commercial FEM code DEFORM-2D. The simulated results for SPR process joining between GFRP and Al alloys were confirmed by the same conditions as experimental trials.

• Journal of Welding and Joining
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• 제15권1호
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• pp.116-124
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• 1997

A scope of this study is to establish the optimum plasma spray conditions for fine ($5\mu\textrm{m}$) $Al_2O_3$ powder. However, the flowability of the $Al_2O_3$ powder is not so good because of irregular particle shape and fine particle size. Therefore, powder feeding system was modified by 1) change of powder feeding line material from polymer to copper 2) shorten the powder feeding tube length 3) heating the powder feeding system to $80^{\circ}C$4) vibrating the powder feeding line continuously, in order to feed the fine powder homogeneously. The homogeneous powder feeding conditions were obtained with the modified powder feeding system by controlling the powder carrier gas flow and the powder flow rate indicator. The best plasma spraying conditions for the fine $Al_2O_3$ powder were found out as 40kw gun power, 80 g/min. powder feed rate and 50 mm working distance after characterizing the microstructure, hardness and wear loss of the $Al_2O_3$ coating layer.