• Clean Technology
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• v.2 no.2
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• pp.165-175
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• 1996

Cutting fluids in machining process are one of the parameters which have serious effects on the environment. A simple method to accomplish the environmentally clean process is to evaluate the effects of cutting fluids and select one which has the least environmental load. In this research, a process planning to select the best cutting fluid is suggested considering both machinability and environmental effects. The selection criteria and evaluation method named AHP are introduced. The planning process is illustrated with drilling characterized as a heavy-duty and low-speed process. Five standard fluids are compared with respect to five environmental attributes. Compounded cutting oils are superior to water-soluble oils in both machinability and environmental effects.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.15 no.2
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• pp.84-88
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• 2016

This study evaluated the structural safety of a heavy-duty integrated machine for grinding wheel forming. Structural analysis was performed to evaluate the structural safety of the base. The base was designed by dividing the single base and detachable base. The analysis conditions were applied to the own weight and the load of component parts. From the structural analysis results, although the stress of the detachable base was decreased, the amount of deformation was increased. If the deformation of the detachable base decreases, it is expected to be safer than the single base.

• Proceedings of the KSME Conference
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• 2008.11b
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• pp.3019-3025
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• 2008

An experimental study was performed to assess the effect of diesel and JP-8 aviation fuel on the spray characteristics, performance and emissions in a single cylinder optical diesel engine. Both fuels were injected via an 8-hole solenoid-driven injector in a common-rail injection system. For better understanding of spray development, the macroscopic images were captured with high speed camera, offered evidences for the results of performance and emissions. From macroscopic spray images, the spray tip penetration of JP-8 shorter than that of diesel while spray angle of JP-8 was wider than that of diesel. It indicates that the vaporization of JP-8 is superior to that of diesel. The lower cetane number of JP-8 resulted in increased portion of premixed combustion. The IMEP with JP-8 is lower than that of diesel-fueled engine. Especially, using JP-8 has a potential for reducing soot.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2011.05a
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• pp.196-197
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• 2011

Rudder, one of the most important component in the marine vessel, is now being decreased life time to serve due to cavitation erosion, vortex current, high flow speed suffer from ship speed going up dramatically. In this study, 10 kinds of thermal spray coating materials(2 of Zn alloy series, 3 of Al alloy series, 3 of Cu alloy series, 2 of STS alloy series) are chosen to apply on specimens and analyze micro structure, metallic composition, properties(porosity, oxidation) by using visual observation, XRD, EDX etc.. Additionally, to refine the characteristic of corrosion endurance for thermal spray coating layer, compared with thermal spray process and 5 kinds of heavy duty painting and AC paint (Anti-Corrosion Paint). Based on above mentioned experimental results, a priority of all coated specimens on corrosion-erosion endurances finalized and summarized there by desirable composition and process of thermal sprayed material properly.

• Journal of the Korean Society for Precision Engineering
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• v.30 no.10
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• pp.1069-1077
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• 2013

These days, the interest of high speed robotic system is increasing because it is very important to get the cost-competitiveness. The parallel kinematic mechanism is more useful than the serial kinematic mechanism. For the reason, the researches on the parallel robot system as a high speed robotic one are have been done by many researchers. In this paper, the research on the design and analysis of the high speed parallel robot has been done by the authors. First, Basic robot structure is designed and modal analysis is studied to get the basic characteristics of the vibrational motion. Second, the harmonic analysis is studied to get the information of the natural frequency in some different designs of the outer-arm of the parallel robot. Finally, actual robot system is designed and implemented and it is confirmed that the analysis results coincide with the experimental results.

• Transactions of Materials Processing
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• v.21 no.1
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• pp.67-74
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• 2012

Although high productivity is possible, cold forged helical gears have not been widely used due to difficulty in achieving mechanical properties as well as dimensional accuracy of the product. Confidence in the gear characteristics also is very important in heavy-duty gear applications. Therefore, the properties of forged gears must be compared to the properties of conventional machined gears. The properties might be different due to the different fabrication processes. In this study, machined and forged products both before and after heat-treated have been compared by measuring the residual stress and involute curve of the tooth. Characteristics of hardness and microstructure were also compared. Additionally, tooth fracture strength was compared for the heat-treated products. Moreover, the tooth strength and the fracture pattern were compared between the machined and forged gears. The forged gear showed decreased changes in residual stress and decreased changes in dimensions when compared to the machined gear before and after heat treatment. The forged gear was over 10% better than the machined gear in tooth strength.

• Journal of Drive and Control
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• v.14 no.4
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• pp.51-60
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• 2017

In this study to develop disaster response robot in complex disaster site, we present the design of hydraulic manipulators for armored robot systems. To this end, we performed voice of customer researches with firefighters and rescue personnel. We created and analyzed the mission scenario of firefighters and rescue personnel in complex disaster situations, and derived the required functions of the robot to successfully perform missions. A heavy-duty, heat resistant, dexterous hydraulic robot manipulators is designed to realize the required functions. The designed robot has been verified through simulations and analysis in terms of the working area of the robot, actuating torques, and temperature analysis.

• Journal of Power Electronics
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• v.19 no.6
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• pp.1351-1365
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• 2019

This paper proposes two modified Z-source inverter topologies, namely an embedded L-Z-source inverter (EL-ZSI) and a coupled inductor L-Z source inverter (CL-ZSI). The proposed topologies offer a high voltage gain with a reduced passive component count and reduction in source current ripple when compared to conventional ZSI topologies. Additionally, they prevent overshoot in the dc-link voltage by suppressing heavy inrush currents. This feature reduces the transition time to reach the peak value of the dc-link voltage, and reduces the risk of component failure and overrating due to the inrush current. EL-ZSI and CL-ZSI possess all of the inherent advantages of the conventional L-ZSI topology while eliminating its drawbacks. To verify the effectiveness of the proposed topologies, MATLAB/Simulink models and scaled down laboratory prototypes were constructed. Experiments were performed at a low shoot through duty ratio of 0.1 and a modulation index as high as 0.9 to obtain a peak dc-link voltage of 53 V. This paper demonstrates the superiority of the proposed topologies over conventional ZSI topologies through a detailed comparative analysis. Moreover, experimental results verify that the proposed topologies would be advantageous for renewable energy source applications since they provide voltage gain enhancement, inrush current, dc-link voltage overshoot suppression and a reduction of the peak to peak source current ripple.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.25 no.5
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• pp.261-268
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• 2013

Technologies for preventing contaminants deposition are a key issue in a modern duct system. When particulate matters deposit inside the exhaust pipes, which are widely used in the Urea-SCR system to reduce $NO_x$ emission from heavy duty diesel engines, many problems arise associated with increased flow resistance and corrosion. Therefore, the development of the urea deposition avoidance technologies is being treated as an important issue of the Urea-SCR system. An analytical study was carried out to investigate the effects of the wall flow around the mixer with the variation of the mixer housing surrounding and supporting the mixer, which is designed to increase the wall flow and then to reduce droplet deposition. The housing angles and the position of the mixer were changed：angles of $0^{\circ}$, $1^{\circ}$, $2^{\circ}$, and $3^{\circ}$, and mixer positions of 0 L, 0.5 L, and 1 L. The axial velocity distributions, maximum velocity, the half-width, and momentum distribution of the wall flow were investigated to examine the effect of the mixer-housing assembly geometry.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2016.10a
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• pp.670-671
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• 2016

AMT(Automated Manual Transmission) is manual transmission that can shift gear automatically by actuator. AMT is applied many commercial vehicles, for easy to operate and high fuel efficiency. 12-Steps AMT that is applied heavy duty commercial vehicle determine gear shifting point by using shifting map and auto shifting logic like other common auto transmissions. But shifting 1-step like common auto transmissions makes shifting crush, clutch abrasion, decrease fuel efficiency problems. In this paper, it deals with design of shifting map and auto shifting logic for 12-step AMT and result of performance test.