• 한국기계가공학회지
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• 제5권4호
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• pp.7-12
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• 2006

Galvanized steel pipe, copper pipe and stainless steel pipe, which is being used in waterworks piping materials. In case of galvanized steel pipe, the precipitation of a product is being generated due to the pollution of the tap water, a white water phenomenon, and various corrosion reaction because a zinc ion is melted by tap water. And in case of a cupper pipe, many problems which is harm in sanitation appeared because of a inflow of harmfulness substance by a frequent accident of a water leakage. So, to prevent these problems, it is substituted for stainless steel pipe. However, those problems is still occurring because of badness of welding, a problem of a water leakage in connection part, and a increment of construction expenses. Therefore, this research has examined the laying period according to each piping thickness and a corrosion shape according to each laying depth after laying in various soils(sandy loam, loamy, clay loam, clay) using galvanized steel pipe, copper pipe, and stainless steel pipe. That is, we has studied the data which is necessary for a rational method of preserving the quality of water by examining the corrosion properties of piping materials in the soil environment which waterworks piping materials is being used.

• Maxillofacial Plastic and Reconstructive Surgery
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• 제42권
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• pp.18.1-18.9
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• 2020

Background: Bone grafting has been considered the gold standard for hard tissue reconstructive surgery and is widely used for large mandibular defect reconstruction. However, the midface encompasses delicate structures that are surrounded by a complex bone architecture, which makes bone grafting using traditional methods very challenging. Three-dimensional (3D) bioprinting is a developing technology that is derived from the evolution of additive manufacturing. It enables precise development of a scaffold from different available biomaterials that mimic the shape, size, and dimension of a defect without relying only on the surgeon's skills and capabilities, and subsequently, may enhance surgical outcomes and, in turn, patient satisfaction and quality of life. Review: This review summarizes different biomaterial classes that can be used in 3D bioprinters as bioinks to fabricate bone scaffolds, including polymers, bioceramics, and composites. It also describes the advantages and limitations of the three currently used 3D bioprinting technologies: inkjet bioprinting, micro-extrusion, and laserassisted bioprinting. Conclusions: Although 3D bioprinting technology is still in its infancy and requires further development and optimization both in biomaterials and techniques, it offers great promise and potential for facial reconstruction with improved outcome.

• International Journal of Precision Engineering and Manufacturing
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• 제2권2호
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• pp.38-47
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• 2001

This paper decribes the development of computer-aided design of a very precise progressice die for lead frame of semiconductor chip. The approach to the system is based on knowledgr-based rules. Knowledge of fie이 experts. This system has been written in AutoLISP using AutoCAD ona personal computer and the I-DEAS drafting programming Language on the I-DEAS mater series drafting with on HP9000/715(64) workstation. Data exchange between AutoCAD and I-DEAS master series drafting is accomplished using DXF(drawing exchange format) and IGES(initial graphics exchange specification) files. This system is composed of six main modules, which are input and shape treatment, production feasibility check, strip layout, data conversion, die layout, and post processing modules. Based on Knowledge-based rules, the system considers several factors, such as V-notches, dimple, pad chamfer, spank, cavity punch, camber, coined area, cross bow, material and thickness of product, complexities of blank geometry and punch profiles, specifications of available presses, and the availability of standard parts. As forming processes and the die design system using 2D geometry recognition are integrated with the technology of process planning, die design, and CAE analysis, the standardization of die part for lead frames requiting a high precision process is possible. The die layout drawing generated by the die layout module s displayed in graphic form. The developed system makes it possible to design and manufacture lead frame of a semiconductor more efficiently.

• 한국기계가공학회지
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• 제20권12호
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• pp.24-29
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• 2021

Recently, owing to the high demand for eco-friendly cars in the automotive industry, noise and vibrations have become major challenges. The use of laminated damping steel is increasing in response to these demands. Laminated damping steel is primarily used in sound insulation plates. The vibration energy is converted into thermal energy due to the viscoelastic resin being located between two steel sheets and being able to damp the vibrations when an external force, such as, noise or vibration is applied to the steel plate. Laminated damping steel is chiefly applied to dash panels in automotive body parts, and because of its structure, junction technology for bonding with other components is necessary. However, there has not been sufficient research conducted on junctions. In this study, regardless of the electrode shape, in the range of 4.0 ~ 8.0 kA welding current, the same welding force and welding time were applied which were 2.8 kN and 200 m/s (12 cycles) and the tensile shear load and nugget size were analyzed after the resistance spot welding between different materials of laminated damping steel with a thickness of 1.035 mm. The results show that in the range of 5 ~ 8 kA welding current, 1.035 mm laminated damping steel meets the MS181-15 standard, which is the technical standard of Hyundai-Kia Motors.

• 한국CDE학회논문집
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• 제1권3호
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• pp.203-214
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• 1996

An information sharing system, namely World Design View, is developed for browsing product design data on the World Wide Web environment. For the last few years information sharing has been rapidly emerging as an important research issue in the areas of concurrent engineering, product data management, virtual manufacturing, and so on. Since we are mainly concerned with product development, the key information that needs be communicated and shared is product data. The developed system puts the major advantages of STEP, OODB, and VRML together. The STEP standard provides a consistent data exchange format and application interfaces among different CAD/CAM systems. OODB is efficient and effective in dealing with complex data structures often found in engineering applications. Virtual worlds for 3-D product models can be created by VRML which is networked via the global Internet and hyperlinked with WWW. The World Design View system can support for members of virtual design teams, possibly distributed all over the world, to share 3-D shape information quickly and easily.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1998년도 가을 학술발표논문집(II)
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• pp.301-306
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• 1998

Aggregate as the component of High Flowing Concrete has much influence on the properties of High Flowing Concrete according to the quality and condition because the aggregate occupy a lot of concrete volume. The shape and size of aggregate affect a lot spatial passibility and fillingability. The segregation is easy to occur when the rate of Fine aggregate is high so that Fluidity is much affected by aggregate factor. In this study, therefore, we try to understand the various fluidity according to the fine aggregate of standard grade rang, the size of Coarse aggregate and the rate of fine aggregate to confirm the manufacturing possibility of High Flowing Concrete by examination on the influence of fresh state of high flowing concrete such as flowability, reinforcement passibility, fillingability, segregation resistance.

• 한국공작기계학회:학술대회논문집
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• 한국공작기계학회 2001년도 춘계학술대회 논문집(한국공작기계학회)
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• pp.34-39
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• 2001

The median barrier is one of the roadside hardware to prevent severe human and property damage from highway traffic accidents. The foreign standard of concrete median barrier was introduced and implemented without modification fitting to domestic vehicle and highway condition. In a car accident, median barrier doesn't protect vehicle effectively, especially for heavy vehicle such as bus and heavy truck. The purpose of this study is to develop the optimal performance design of concrete median barrier using the design of experiment with crash simulation analysis which is done by Pam-Crash that is one of the commercial crash simulation software. As a result of this study, an optimal design of concrete median barrier is obtained considering von Mises stress, volume and COG acceleration of truck.

• 한국공작기계학회:학술대회논문집
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• 한국공작기계학회 2001년도 춘계학술대회 논문집(한국공작기계학회)
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• pp.137-142
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• 2001

Since recent production system becomes that of the small quantity, large volume with high quality production, accurate and high speed inspection system is required. In such situation, noncontact 3D measurement system which utilized CCD cameras is useful technique in terms of system cost, speed of data acquisition, measuring accuracy and application. However, it has low accuracy compared with contact 3D measurement system because of the camera distortion, non uniformity of laser distribution and so on. For those reasons, in this paper precision enhancement method is studied considering radial camera distortion, and laser distribution. A distortion correction method is applied even to the standard lens. The laser slit beam trajectory is determined by 3 method: based of the Gaussian function signal approximation, the median method, the center of gravity method and the peak point of the Gaussian function method.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2004년도 춘계학술대회논문집
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• pp.753-758
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• 2004

This study is to suggest a probabilistic design determining configurations of slider air bearings with the dimensional manufacturing tolerances of the ABS. The probabilistic design problem is formulated to minimize the variation in flying height from a target value while satisfying the desired probabilities keeping the pitch and roll angles within suitable range. The proposed approach first solves the deterministic optimization problem. Then, beginning with this solution, the RBDO is continued with the probabilistic constraints affected by the random variables with a fixed standard deviation in normal distribution. The RBDO results are directly compared with the values of the initial design and the results of the deterministic optimization, respectively. The reliability analyses are performed by the descriptive sampling (DS) to show the effectiveness and accuracy of the proposed approach. It is demonstrated that the proposed RBDO approach can efficiently obtain an optimum solution satisfying all the desired probabilistic constraints.

• 한국소음진동공학회논문집
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• 제14권8호
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• pp.695-701
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• 2004

This study is to suggest a Probabilistic design determining configurations of slider air bearings with the dimensional manufacturing tolerances of the ABS. The probabilistic design problem is formulated to minimize the variation in flying height from a target value while satisfying the desired probabilities keeping the pitch and roll angles within a suitable range. The proposed approach first selves the deterministic optimization problem. Then, beginning with this solution, the RBDO is continued with the probabilistic constraints affected by the random variables with a fixed standard deviation in normal distribution. The RBDO results are directly compared with the values of the initial design and the results of the deterministic optimization, respectively. The reliability analyses are performed by the descriptive sampling (DS) to show the effectiveness and accuracy of the proposed approach. It is demonstrated that the Proposed RBDO approach can efficiently obtain an optimum solution satisfying all the desired probabilistic constraints.