• Transactions of the Korean Society of Machine Tool Engineers
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• v.17 no.5
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• pp.10-22
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• 2008

In an automotive body structure, a design configuration that fulfills structural requirements such as deflection, stiffness and strength is necessary for structural design and is composed of various components. The integrated design is used to obtain a minimum weight structure with optimal or feasible performance based on conflicting constraints and boundaries. The mechanical design must begin with the definition of one or more concepts for structure and specification requirements in a given application environment. Structural optimization is then introduced as an integral part of the product design and used to yield a superior design to the conventional linear one. Although finite element analysis has been firmly established and extensively used in the past, geometric and material nonlinear analyses have also received considerable attention over the past decades. Also, nonlinear analysis may be useful in the area of structural designs where instability phenomena can include critical design criteria such as plastic strain and residual deformation. This proposed approach can be used for complicated structural analysis for an integrated design process with the nonlinear feasible local flexibilities between system and subsystems.

• Proceedings of the KIEE Conference
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• 2004.11a
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• pp.233-236
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• 2004

Recently, the polymer insulators that are used for high voltage applications have some advantages such as light weight, small size, vandalism resistance, hydrophobicity and easy making process. During outdoor service of polymer insulators, the surface of the insulating material is frequently subjected to moisture and contamination that lead to dry band arcing. Their tracking resistance, erosion resistance, end sealing and shed design are very important because dry band arcing causes degradation of polymer surface. The shape design of porcelain insulator is formalized but design standard for polymer insulator is no standardized up to now, much research is necessary in real condition. In this paper, the surface and tracking properties of polymer suspension insulator for power transmission is investigated with ICP-AES, SEM, EDX, tracking wheel test and flashover voltage test. The diagnosis of insulator sample in tracking test hass been analyzed by leakage current STRI Guide and thermal image.

• Transactions of the Korean Society of Automotive Engineers
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• v.1 no.2
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• pp.103-116
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• 1993

Recently, engineering ceramics called as the 3 material have been concerned significantly with some excellent mechanical properties and many functions as new materials for high precision mechanical components and engineering parts for at large. Then, for designing engineering parts using engineering ceramics, bending strength value data with high reliability is more essential than any other mechanical properties. But, because of brittleness and structural characteristic, it is very hard to grind with conventional tools, and the generation of cracks and various defects of engineering ceramics parts during grinding machining process are serious problems. Thus, in present study, surface grinding experiments with various machining conditions using resin bond diamond wheels are carried out to obtain the most excellent guality of testpiece surface and optimum step of grinding process for the high efficient stock removal rate to save running time. As the results from grinding experiments and 3-points bending strength test of ground Al2O3 ceramics parts on Korean Standard, manufactured in our country and Japan, basic technology and know-how to develop the optimum grinding machining conditions and also high bending strength values with high reliability are obtained.

• Journal of Power System Engineering
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• v.6 no.4
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• pp.30-35
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• 2002

This study represents the effects of the material of the air cleaner on the performance in a 4-stroke spark-ignition engine for motorcycles. This study is mainly focused on the possibility of the adopting the STS wire mesh air cleaner of a S.I engine. For investigating the possibility of that, the engine power, the fuel consumption and the exhaust gas analysis were carried out for the synthetic fiber air cleaner and the different size of 200 mesh, 250 mesh, 300 mesh of STS wire mash air cleaner. As the results of this study, the performance of STS wire air cleaner was similar to the fiber air cleaner at 9000 rpm but 300 mesh of STS air cleaner had a high engine power and torque at 9500 rpm. In the case of the synthetic fiber air cleaner the concentration of CO was low at 6500 rpm and in the case of the 300 mesh in STS wire mesh air cleaner the concentration of HC was lowest at all experimental regions.

• Elastomers and Composites
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• v.39 no.3
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• pp.228-233
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• 2004

A bushing is a device used in automotive suspension systems to reduce the load transmitted from the wheel to the frame of the vehicle. A bushing is a hollow cylinder, which is bonded to a solid steel shaft at its inner surface and a steel sleeve at its outer surface. The relation between the force applied to the shaft and the relative deformation of a bushing is nonlinear and exhibits features of viscoelasticity. Since a force-displacement relation for bushings is important for multibody dynamics numerical simulations, the relation is expressed in terms of a force relaxation function and a method of determination by experiments on bushings has been developed. For the nonlinear viscoelastic axial response, Pipkin-Rogers model, the direct relation of force and displacement, has been derived from experiment. It is shown that the predictions by the proposed force-displacement relation are in very good agreement with the experimental results.

• Design & Manufacturing
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• v.15 no.4
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• pp.37-42
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• 2021

The tube necking process increases the thickness of the material, and some of the tube necking products require cutting on the inside of the formed product as a post-process. In order to prevent over-cutting or un-cutting due to increased thickness during cutting, it is necessary to know in advance the increase in thickness after forming. Therefore, in this study, the thickness change according to the tube necking was observed. Aluminum 3003-F and 6061-O were used for the materials used in the experiment, and necking was carried out up to 50% of the outer diameter of the tube through five processes. The two materials were formed under the same conditions, and the thickness of three points was observed in each process. In addition, the thickness increase of the two materials was compared, and the trend of thickness increase according to the cumulative necking ratio was observed. As a result of the experiment, both materials had the smallest thickness at the end of the formed product. In addition, as a result of comparing the thickness measurement values of the two materials, the maximum difference was 0.1mm, indicating that there was no difference in thickness between the two materials.

• Structural Engineering and Mechanics
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• v.90 no.2
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• pp.177-187
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• 2024

In this study, compared two distinct estimation methods (stress charts and regression equations) proposed by the Indian road congress design guideline (IRC:58-2015) to determine flexural stress in Jointed Plain Concrete Pavement (JPCP). The occurrence of critical flexural stresses in pavement slabs is due to the combined effects of wheel loads and temperature. These stresses depend on various factors such as material properties of concrete, soil-subgrade strength, loading, and geometric properties of the slab. In order to account for the practical variability of these factors, critical edge stresses are determined using both methods and compared considering tied concrete shoulder. IRC:58 (2015) suggests, the stresses calculated by both the procedures should provide the same results. However, when these stresses are compared for the same configurations and same loading conditions, large variations are observed. The effect of tied concrete shoulder on reduction in critical edge stress is observed. Based on the study, certain important conclusions and recommendations are presented.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.34 no.5
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• pp.645-649
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• 2010

Induction hardening has been used to improve the torsional strength and characteristics of wear for axle shaft that is used to transmit driving torque from the differential to the wheel in automobiles. After the rapid heating and cooling processes of induction hardening are carried out, the shaft has residual stress and material properties change; this affects the allowable transmitted torque. The objective of this study is to predict the distribution of residual stress and estimate the torsional strength of induction-hardened axle shafts with residual stress. In this study, the finite element method is used to study the thermomechanical behavior of the material, and the results are compared with experimental results. The results indicate that the torsional strength of the axle shaft depends on the surface hardening depth and distribution of residual stress.

• Journal of Biosystems Engineering
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• v.17 no.3
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• pp.229-236
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• 1992

In an effort to localize the spray-dryer which is markedly used for drying food materials, a experiment was carried out with a wheel type atomizer locally designed and manufactured to evaluate the effect of rotational speed, feed rate and physical properties of liquid food material on the droplet size, and to develop a model to predict the droplet size sprayed at various operational conditions. The result are summarized as follows. 1. The frequency of droplet size sprayed from the atomizer at every treatment were similar to normal distributions. 2. Under the test conditions adopted in this study, that is, rotational speed of the atomizer ranging from 15,000 to 20,000 rpm (55.0 m/sec - 73.3 m/sec), feed rate from 14 to 37 kg/hr and viscosity of the material from 1.14 to 350 cP, the mean volume-surface dia. of droplets was decreased as increase in rotational speed and was not affected significantly by the feed rate and viscosity. 3. Through the dimensional analysis, a prediction model was developed as follows : $$\frac{Dvs}{r}=K[\frac{Q}{{\mu}r}]^a[\frac{rN^2}{g}]^b[\frac{{\rho}^2r^3g}{{\mu}^2}]^c[\frac{L}{r}]^d$$ and it was proved that the above model was better in degree of fitness than other models reported. 4. A prediction equation for the droplet size sprayed from the atomizer under the test was expressed as follows : $$\frac{Dvs}{r}=0.0215[\frac{Q}{{\mu}r}]^{0.06}[\frac{rN^2}{g}]^{0.3314}[\frac{{\mu}^2}{{\rho}^2r^3g}]^{0.0158}$$.

• International Journal of Highway Engineering
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• v.7 no.4 s.26
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• pp.9-20
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• 2005

This study was carried out to select most efficient bonding methods of geogrid at the interface of old concrete pavement before placing asphalt overlay layer for reflection cracking retardation. Three bonding methods, a RSC-4 emulsified asphalt, a compound and an unsaturated polyester resin (UPR) were compared in this study. Three types of asphalt mixture (AC 60-80, RLDPE 8%, PG 76-22) and a dense-graded aggregate were used for overlay asphalt pavement. A reinforcing material which consists of a woven fabric underneath a glass fiber grid was used. An expedite test method which is for simulating mixed mode (mode I and II) fracture test was performed using a wheel tracker in laboratory. Cracking development by load repetition was measured as fatigue life (number of load cycle) and expansion of specimen body were measured for each test specimen. The results showed that UPR was the best and RSC-4 the next. But considering field applicability, RSC-4 was considered as an appropriate choice for bonding reinforcing material.