• 한국정밀공학회지
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• 제17권4호
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• pp.7-21
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• 2000

This paper describes an overview of the thixoforming and thixomolding processes. Semi-solid metalworking (SSM), which is called the thixoforming process of aluminium materials, incorporates the elements of both casting and for the manufacture of near net shape parts. The SSM has some advantages such as net shape or near net shape manufacturing, the ability to form thin walls, excellent surface finish, tight tolerance, and excellent dimensional precision. The thixomolding process of Mg alloy (AZ9l) is a combination of two technologies both conventional die casting and plastic injection molding. The feed material used is a machined chip with a geometry of approximately 1 mm square and a length of 2~3 mm. The semi-solid forming (SSF) of high quality aluminium and magnesium parts will be established in the automotive and electronic industry, in the future. The hybrid method of casting/forging has been caused attention. This process uses a preformed material made by casting instead of the wrought material and finishes it by a single forging process. This process is expected to lower costs without sacrificing the mechanical and finishes it by a single forging process. The process is expected to lower costs without sacrificing the mechanical properties. The authors, intending that the casting/forging process contributes to a reduction in production cost of aluminum automotive parts in Korea, describes the feature of the casting/forging process, aluminum alloys suitable for the cast preform, microstructure and mechanical properties of the cast preform, application examples of cast/forging, and further study.

• 자동차안전학회지
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• 제8권4호
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• pp.24-30
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• 2016

In Korea, the Vehicle Dismantler and Recycler industry is supervised by the Ministry of Land, Infrastructure and Transport under the Automobile Management Act. Also, Korean Automotive recycling businesses are supervised by the Minister of Environment under the Resource Recirculation Act. The main concern of the Minister of Environment is how the wastes from Dismantled vehicles will be environmentally removed, stored, treated, recycled or disposed. In 2000, the European Union (EU) adopted the End-of-Life Vehicles Directive (2000/53/EC) which required Members to ensure the collection, treatment and recovery of end-of-life vehicles (ELVs). The Directive, the most tightly regulated and precautionary legal systems, required that the last owner of a vehicle could drop off the ELV at an authorized treatment facility and that the producers of the ELV should pay the cost of the program. The adoption of the ELVs directive has led the development of Automotive Dismantler and Recycler networks to reuse, refurbish, remanufacture, recycle and recover parts and materials embedded in ELVs. Also, the ELVs directive which has had an insignificant impact on Korean manufacturers has strong presence in the European market and has been successfully externalized on them. The Korean manufacturers not only achieve the 85% recycling target set by the ELVs directive but also meet the Extended Producer Responsibility (EPR) which requires manufacturers to contribute dismantling process. In order to improve the Korean vehicle dismantling and recycling system, the Automobile Management Act and the Resource Recirculation Act should be harmonized. Particularly the roles of the Ministry of Land, Infrastructure and Transport and the Minister of Environment should be sharply divided. Like Japan, the ELV management needs to be highly centralized, regulated, and controlled by the ministry specialized in Vehicle, namely the Ministry of Land, Infrastructure and Transport and the sub organizations. Like EU Members, recovery, reuse, and recycling must be distinguished. Recovery is defined as the final productive use of the parts and materials embedded in ELVs, which includes reuse and remanufacture of parts and recycling of the other materials. Dismantling process and reuse and remanufacture of parts must be governed by the Ministry of Land, Infrastructure and Transport. For environmental recycling or disposal of waste materials, such as CFCs, glass and plastic material, and toxic substances, governmental financial support system should be in place.

• Maxillofacial Plastic and Reconstructive Surgery
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• 제28권3호
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• pp.262-267
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• 2006

The term temporomandibular disorders is used to describe a group of conditions that involve the temporomandibular joint, masticatory muscles, and associated structures. Many modalities have been proposed for treating temporomandibular disorders, including medication, physical therapy, occlusal stabilization splints with or without manual repositioning, surgery, and arthrocentesis. Temporomandibular disorders are treated in a step-wise manner. Initially, conservative treatment is used. Depending on the response, more aggressive interventions may be necessary. This usually takes the form of arthrocentesis. Arthrocentesis is used in the treatment of not only acute, closed, and locked TMJs but also various other temporomandibular disorders. Recently, the intra-articular injection of sodium hyaluronate after arthrocentesis was shown to have long-term palliative effects on TMJ symptoms. Synovial fluid consists of plasma and glycosaminoglycan, including hyaluronic acid derived from synovial cells. Sodium hyaluronate, the sodium salt of hyaluronic acid, is a high-molecular-weight polysaccharide and a major component of synovial fluid. This highly viscous substance has analgesic properties, lubricant effects, and anti-inflammatory actions; it causes cartilage formation and plays a role in the nutrition of avascular parts of the disc and condylar cartilage. We conclude that the intra-articular injection of sodium hyaluronate is effective for treating temporomandibular disorders.

• 소성∙가공
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• 제18권2호
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• pp.122-127
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• 2009

The injection mold with multi-cavity is essential for mass production of plastic products. Multi-cavity molds are designed to geometrically balanced runner system to uniformly fill to each cavity. However, despite geometrical balanced runner system, filling imbalances between cavity to cavity have always been observed in injection molding. To solve these problems, many studies such as Melt Flipper, RC Pin, and others have been presented. The results of these studies have been an effect on filling balances in multi-cavity molds. But, those have had a limitation that additional insert parts must have existed in the mold. In this study, a new runner system is suggested for filling balance between cavity to cavity using "Melt-Buffer" with simple change of runner shape. A series of simulation to confirm feasibility of Melt-Buffer's effects was conducted using injection molding CAE program. Also, a series of injection molding experiment was conducted using plastic materials such as ABS and PP. As results of this study, feasibilities of filling balances by Melt-Buffer were confirmed.

• 한국생산제조학회지
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• 제22권4호
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• pp.693-699
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• 2013

Environmental issues are attracting increasing interest worldwide, and accordingly, environmental regulations for vehicles are being made more stringent. As a result, the car industry is conducting studies focusing on fuel efficiency and lightweight vehicles. To manufacture lightweight vehicles, existing steel parts are replaced by composite materials and lightweight metals. In this study, the fatigue life of a new material for manufacturing lightweight car door hinges was predicted using a finite-element analysis program. The existing steel material was replaced by carbon-fiber-reinforced plastic (CFRP) and aluminum alloy 6061, and the test results were analyzed. The maximum stress decreased by approximately three times, whereas the fatigue life and safety factor increased. When only CFRP was used, its allowable stress, safety factor, and fatigue life were excellent, but the sagging of the product exceeded the allowable value, which posed a limitation in use. Therefore, it seems desirable to use an appropriate combination of steel, AA6061, and CFRP for this product.

• Design & Manufacturing
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• 제6권2호
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• pp.90-95
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• 2012

The sheet metal forming proceccing is very important and indispensable in the automotive industry because the accuracy of prsee worked parts is directly related to the automotive quality. But when making mold it is difficult and expensive to modify mold. mold design technology is a critical technology in press plastic working. When design the mold there are lots of variables in press plastic working according to worked material, mold materials, conditions of heat treatment, clearance and so on. Abrasion of mold depends on these kind of conditions and sheared surface which is crucial for quality of product also depends on them. In this study, we conduct research on abrasion loss of mold according to 8, 10 and 12% of clearance for thickness of 1.0mm of worked material out of mold design variables of the products whose worked materials are high carbon steel and carbon tool steel by a practical experiment and perform a comparative evaluation of difference of abrasion loss mold with the alloy tool steel (STD11) and Tungsten Carbide (WC).

• International Journal of Automotive Technology
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• 제1권1호
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• pp.35-41
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• 2000

The crashworthiness of vehicles with finite element methods depends on the geometry modeling and the material properties. The vehicle body structures are generally composed of various members such as frames, stamped panels and deep-drawn parts from sheet metals. In order to ensure the impact characteristics of auto-body structures, the dynamic behavior of sheet metals must be examined to provide the appropriate constitutive relation. In this paper, high strain-rate tensile tests have been carried out with a tension type split Hopkinson bar apparatus specially designed for sheet metals. Experimental results from both static and dynamic tests with the tension split Hopkinson bar apparatus are interpolated to construct the Johnson-Cook and a modified Johnson-Cook equation as the constitutive relation, that should be applied to simulation of the dynamic behavior of auto-body structures. Simulation of auto-body structures has been carried out with an elasto-plastic finite element method with explicit time integration. The stress integration scheme with the plastic predictor-elastic corrector method is adopted in order to accurately keep track of the stress-strain relation for the rate-dependent model accurately. The crashworthiness of the structure with quasi-static constitutive relation is compared to the one with the rate-dependent constitutive model. Numerical simulation has been carried out for frontal frames and a hood of an automobile. Deformed shapes and the Impact energy absorption of the structure are investigated with the variation of the strain rate.

• 한국정밀공학회지
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• 제29권1호
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• pp.96-102
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• 2012

The current establishment of car engineering plastic piping polyethylene (PE) tube used as bonding state or part of the health or safety of fusion is very important. A part of these fusion methods to determine the soundness of the short-term trials and long-term tests can be largely classified. Typical tests included short-term strength, tensile strength, impact strength, compressive strength, resiliency and compression. Polyethylene (PE) pipes installed in the domestic terms of overall penetration rate of 45% has been used. However, polyethylene (PE) pipes have reliability problems, and these occurs mostly in part by defective welding. Therefore, the test is necessary for safety. Non-destructive methods (ultrasonic testing) are difficult to be used. Therefore, Polyethylene (PE) pipe are used. Fusion of thses materilas is necessary in these field however, its technical, and basic research has not been studied well. In this research, short-term strength of welding parts, its tensile strength, hardness, fatigue, and microstructure have been analyzed to find the optimum process conditions to improve mechanical properties.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2008년도 추계학술대회논문집
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• pp.230-236
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• 2008

In this paper, a model-based stick-slip compensation for the micro-positioning is proposed using an enhanced stick-slip model based on statistical rough surface contact model. The smart structure is comprised with PZT (lead (Pb) zirconia (Zr) Titanate (Ti)) based stack actuator incorporating with the PID (Proportional-Integral-Derivative) control algorithm, mechanical displacement amplifier and positioning devices. For the stick-slip compensation, the elastic-plastic static friction model is used considering the elastic-plastic asperity contact in the rough surfaces statistically. Mathematical model of system for the positioning apparatus was derived from the dynamic behaviors of structural parts. PID feedback control algorithms with the developed stick-slip model as well as feedforward friction compensator are formulated for achieving the accurate positioning performance. Experimental results are provided to show the performances of friction control using the developed positioning apparatus.

• 한국정밀공학회지
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• 제17권4호
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• pp.226-232
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• 2000

This paper develops a finite element model for studying the crashworthiness analysis of a mid-size truck. A simulation for a truck frontal crash to a rigid barrier using the model is performed with PAM-CRASH installed in super computer SP2. Full vehicle model is composed of 86467 shell elements, 165 beam elements and 98 bar elements, and 86769 nodes. The model uses four material model such as elastic, elastic-plastic(steel), rigid and elastic-plastic(rubber) material model which are in PAM-CRASH. Frame and suspension system are modeled with 28774 shell elements and 31412 nodes. Cab is modeled with 34680 shell elements and 57 beam elements, and 36254 nodes. Bumper is modeled with 2262 shell elements, and 2508 nodes. Axle, steering shaft, etc are modeled using beam or bar elements. Mounting parts are modeled using rigid bodies. Bodies are interconnected using nodal constrains or joint options. To verify the developed model, frontal crash test with 30mph velocity to a rigid barrier is carried out. In the crash test, vehicle pulse at lower part of b-pillar is measured, and deformed shapes of frame and driver seat area are photographed. Those measured vehicle pulse and photographed pictures are compared those from the simulation to verify the developed finite element model.