• Transactions of the Korean Society of Mechanical Engineers A
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• v.30 no.8 s.251
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• pp.916-922
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• 2006

In recent years there has been a growing interest for the use of natural fibers in composite applications due to their low cost, environmental friendliness, and good mechanical properties. The purpose of this study is to determine the characteristic of bending strength on bamboo fiber reinforced polymer composites. The parameters of RTM process depend on the weight ratio of bamboo fiber and resin, the number of bamboo ply and amount of hardening agent. Mechanical properties was investigated for each process factor of polymer composites. Test result shows that bending strength was a maximum(approximately 85MPa) value when composite thickness was 6mm and weight ratio of resin was 13%.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.6 no.3
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• pp.112-118
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• 2007

Recently, the machine tools called multi-task machines, which mounted rotary axes on the table or spindle are used increasingly. Accordingly, multi-task machine tool takes a growing interest on the motion accuracy of feed drive system. In this study, measurement and diagnosis of motion errors ware attempted from circular pattern obtained by using DBB (Double ball bar) device. Those were obtained at both clockwise and counter clockwise motions in mutually perpendicularly intersecting three planes. The reliability of error measurement system for multi-task machine tool was verified by the direct test cutting.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.6 no.3
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• pp.31-37
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• 2007

Recently, the machine tools called multi-task machines, which mounted rotary axes on the table or spindle are used increasingly. Accordingly, multi-task machine tool takes a growing interest on the motion accuracy of feed drive system. In this study, measurement and diagnosis of motion errors ware attempted from circular pattern obtained by using DBB (Double ball bar) device. Those were obtained at both clockwise and counter clockwise motions in mutually perpendicularly intersecting three planes. The reliability of error measurement system for multi-task machine tool was verified by the direct test cutting.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1997.10a
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• pp.825-828
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• 1997

The market share of plastic fuel tube in automobile part is now growing rapidly. Especially fuel tube makers have had their efforts to develop tube module not only with dimensional accuracy, spring back and cost competitiveness. In this study, we used steam bending process for heat relaxation on PA12 plastic fuel tube's 128 types experimental bending conditions. we present the results of this process system in term of dimensional accuracy, and spring back.

• Proceedings of the KSME Conference
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• 2003.11a
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• pp.1642-1647
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• 2003

The market of the horizontal axis washing machine (drum washing machine) has been growing drastically in Korea by about 80% annually since 2000. As market grows fast, the customerTs demands concerning quality becomes more strict and various. Imbalance sensing is a key technology to reduce the NVH problem in a washing machine, because the laundry is time-variant and uncontrollable source of imbalance, which can cause more than 200kgf exciting force. In this paper, imbalance-sensing methods are briefly reviewed, new acceleration sensing circuits are examined, and finally the control algorithm of spinning process is proposed and validated.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.11 no.4
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• pp.131-137
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• 2012

This article is about using the fuel mixed with 10% and 20% bio-ethanol to gasoline for the engine as a way to reduce carbon emission before commercializing future automobiles like fuel cell cars. The fuel mixed with 10% and 20% bio-ethanol showed output equivalent to that of the previous gasoline fuel. CO and $CO_2$ emission was somewhat reduced, but the difference was not significant. And the consumption of the fuel increased slightly. However, bio-ethanol is produced from bio mass growing with the absorption of carbon dioxide, so the total amount of carbon dioxide did not increase according to the result. In NOx, as the use of ethanol increases, the effect of reduction gets greater, and the emission of oxygen showed almost no change compared with gasoline.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1996.11a
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• pp.194-199
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• 1996

Grinding burn formed on the ground surface is related to the maximum temperature of workpiece surface and wheel temperature in the grinding process. The thermal characteristics of workpiece and grinding conditions on the surface temperature of the oxidation growing layer after get out of contact with the grinding wheel. The assumption used in grinding power signatures leads to the local temperature distribution between grinding wheel and workpiece, i.e., a single curve determines temperatures anywhere within the grinding wheel at anytime. This information is useful in the study of the grinding bum penetration into the wheel and thus provides an presentation of grinding trouble monitoring for the burning. On the basis of grinding power signatures in the wheel, thermally optimum conditions are defined and controlled. To cope with grinding burn, the use of grinding power signatures is an effective monitoring systems when occurring the grinding process. In this paper, the identified parameters suggested in this study which are derived from the grinding power signatures are presented.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.10 no.7
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• pp.3171-3191
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• 2016

Due to growing demand on wireless data traffic, a large number of different types of base stations (BSs) have been installed. However, space-time dependent wireless data traffic densities can result in a significant number of idle BSs, which implies the waste of power resources. To deal with this problem, we propose an active state control algorithm based on semi-Markov decision process (SMDP) for a heterogeneous network. A MDP in discrete time domain is formulated from continuous domain with some approximation. Suboptimal on-line learning algorithm with a random policy is proposed to solve the problem. We explicitly include coverage constraint so that active cells can provide the same signal to noise ratio (SNR) coverage with a targeted outage rate. Simulation results verify that the proposed algorithm properly controls the active state depending on traffic densities without increasing the number of handovers excessively while providing average user perceived rate (UPR) in a more power efficient way than a conventional algorithm.

• Journal of Environmental Impact Assessment
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• v.15 no.1
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• pp.13-22
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• 2006

The Korean government adopted the integrated stream water management policy recently with growing perception that natural disasters and pollution in Korea have been due not only to such human factors as urbanization and industrialization, but also to the policy of functionally separated management of irrigation, flood control and ecological management. Contrary to its good intention, research result shows that it is not realistic to expect that this new integrated policy in Korea will work well. In order to be an effective policy and program evaluation, this paper suggests that evaluation indicator on related programs and projects should be made through bottom-up process. For example, environmental benefit should be taken into account rather than just economic benefit, and cultural and social characteristics in the project region should be also considered seriously.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.21 no.4
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• pp.362-367
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• 2008

We have Manufactured the low-k dielectric interlayer fabricated by plasma enhanced chemical vapor deposition (PECVD), The thin film of SiOCH is studied correlation between components and Dielectric constant. The precursor was evaporated and introduced with the flow rates from 16 sccm to 25 sccm by 1sccm step in the constant flow rate of 60 sccm $O_2$ in process chamber. The chemical characteristics of SiOCH were analyzed by measuring FT/IR absorption lines and obtained each dielectric constant measuring C-V. Then compare respectively. ILD of BTMSM/$O_2$ could have low dielectric constant about $k\sim2$, and react sensitively. Also dielectric constant could be decreased by the effects of decreasing $CH_3$ and growing Si-O-Si(C) after annealing process.