• Journal of Korean Society of Industrial and Systems Engineering
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• v.17 no.32
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• pp.121-126
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• 1994

Setup Time Reduction is an important aspect of the Just-in-Time(JIT) and Zero Inventory(Zl) Concepts since it supports reductions in manufacturing lead times and inventories. It also enables small lot sizes and kanban systems implementation for material flow - achieving major improvements in production floor management. One concept fundamental to the pursuit of JIT production in Japan and other countries is adoption of a setup time reduction. This paper looks at the necessities of setup time reduction and the relations to machine utilization. By using an EOQ model for evaluate the effect of setup time reduction, we get the results that over 75 % reduction in setup time is obtain the desired results in the lot size reduction.

• Communications for Statistical Applications and Methods
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• v.23 no.2
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• pp.93-103
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• 2016

In the paper, we discuss dimension reduction of predictors ${\mathbf{X}}{\in}{{\mathbb{R}}^p}$ in a regression of $Y{\mid}{\mathbf{X}}$ with a notion of sufficiency that is called sufficient dimension reduction. In sufficient dimension reduction, the original predictors ${\mathbf{X}}$ are replaced by its lower-dimensional linear projection without loss of information on selected aspects of the conditional distribution. Depending on the aspects, the central subspace, the central mean subspace and the central $k^{th}$-moment subspace are defined and investigated as primary interests. Then the relationships among the three subspaces and the changes in the three subspaces for non-singular transformation of ${\mathbf{X}}$ are studied. We discuss the two conditions to guarantee the existence of the three subspaces that constrain the marginal distribution of ${\mathbf{X}}$ and the conditional distribution of $Y{\mid}{\mathbf{X}}$. A general approach to estimate them is also introduced along with an explanation for conditions commonly assumed in most sufficient dimension reduction methodologies.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2012.10a
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• pp.169-174
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• 2012

Reduction unit is one of the most important components for railway vehicle because torque of motor must be transmitted to wheels of vehicle by reduction unit. However, According to advanced studies, it has been often broke down due to the damage, fatigue and wear of gear. To solve this problem, defect diagnosis methods of gear have been mainly using the vibration diagnosis technology through vibration waveform and frequency analysis. However, We should know vibration characteristics of normal state reduction unit prior to defect diagnosis. So in this paper, We had analyzed vibration characteristics of reduction unit in order to utilize monitoring system development. Comparison of targets is the vibration characteristics of normal state reduction unit about Electric Multiple Unit(EMU) and the High-speed trains(KTX, KTX II).

• Nuclear Engineering and Technology
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• v.35 no.1
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• pp.25-34
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• 2003

The research on the development of the fault monitoring system for the thermal reduction reactor has been performed preliminarily in order to support the successful operation of the thermal reduction reactor. The final task of the development of the fault monitoring system is to assure the integrity of the thermal$_3$ reduction reactor by the acoustic emission (AE) method. The objectives of this paper are to identify and characterize the fault-induced signals for the discrimination of the various AE signals acquired during the reactor operation. The AE data acquisition and analysis system was constructed and applied to the fault monitoring of the small- scale reduction reactor, Through the series of experiments, the various signals such as background noise, operating signals, and fault-induced signals were measured and their characteristics were identified, which will be used in the signal discrimination for further application to full-scale thermal reduction reactor.

• Transactions of the Korean Society of Automotive Engineers
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• v.10 no.5
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• pp.138-146
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• 2002

The new type of vibration reduction material far an automotive interior, which is spray-type liquid material, is developed in this study The new material has better damping property and lower mass density than other damping materials, for example asphalt sheet. It can be sprayed by an automatic robot, so it is expected to improve productivity and cut down manpower. And it solves a poor adhesion problem and makes an automotive to be lightweight by optimizing spray process. So, It is a next generation automotive vibration reduction material. In this paper, the chemical process for making the new damping materials is described. And then, the damping properties of the vibration reduction materials are analyzed by modal testing of damping treatment specimens. The new vibration reduction materials have good damping properties than asphalt sheet in the experimental results.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.32 no.1
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• pp.1-9
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• 2000

This study was carried out to improve the opacity of printing paper. Conventional filler loading enhanced the opacity of paper, but subsequently caused reduction of paper strength of paper. We try to seek a new filler loading method so-called beater loading that enhances opacity of paper as well as sustained desire strength. In our experiment, comparing to direct loading method, the beater loading method enhanced 0.8% of opacity and 0.2% of brightness. This also decreased the rates of strength reduction of paper. Therefore, the results obtained in this study indicated that beater loading was a very effective method to improve the opacity of paper while not to decreased so much of paper strength.

• Journal of Korean Society of Water and Wastewater
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• v.18 no.4
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• pp.508-514
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• 2004

Industrial and municipal wastewater treatment plants produce large amounts of sludge cakes for final disposal. This problem is an inevitable drawback inherent to the activated sludge process. Both the reduction of the amount of sludge produced and improvement of its dewaterability are presently very important issue also in Korea. So many pre-treatment processes have been developed in order to improve sludge dewatering efficiency. In this study the effects of hydrogen peroxide and paper sludge mixing processes were considered as reasonable alternatives to enhance sludge dewaterability. The CST of sludge was significantly decreased, and dewaterability improved by hydrogen peroxide oxidation treatment. The optimum dosage of hydrogen peroxide was proved to be 10mg/g-TS (when TS of sludge was 2%) with the conditions of pH 4 and only 1~2 minutes of reaction time. The mixing of paper sludge with sewage sludge was turned out to be very effective in reduction of sludge cake; 30% of sludge cake reduction was accomplished. Optimum mixing ratio of paper sludge was about 30%(v/v). This process also could save 25% of polymer to be required. These two alternatives are somewhat realistic, but it was concluded that paper sludge mixing process will be the best choice.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.53 no.5
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• pp.283-294
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• 2004

This paper introduces the new Direct Torque Control(DTC) method based on the estimated torque in Switched Reluctance Motor(SRM) and applies the proposed DTC to SRM for the instantaneous torque ripple reduction. The nonlinear characteristics of SRM is considered in the calculation of the estimated torque and the theory is described in this paper. Current control is one of the kernel elements of torque controller and the performance of the current control should be high for this work. But the conventional PI current control has a weak point in SRM application because of motional EMF. Consequently, this paper makes up for the weakness of PI controller through present of new current controller, that is termed the non-interference current control. The ability of proposed torque and current controller is verified through simulation and experiment.

• Proceedings of the Korea Society for Energy Engineering kosee Conference
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• 1992.11a
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• pp.39-40
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• 1992

This paper dealt with the manufacturing of binary alloy catalyst and showed simple electrochemical method for determing catalytic activity of oxygen reduction in acid or alkaline electrolyte. The catalyst was prepared by impregnating transition metal salts on platinum or silver particles adsorbed before on carbon paper substrate. The electrochemical characteristics of the catalysts was investigated with carbon paper electrode or PTFE-boned porous electrode and then cathodic current densities and tafel slopes were compared. As a result, of all binary catalysts utilized in this work, Pt-Fe, Pt-Mo showed better oxygen reduction activity than pure platinum catalyst in acid electrolyte and Ag-Fe, Ag-Pt, and Ag-Ni-Bi-Ti catalyst did than pure silver catalyst in alkaline electrolyte. The current density of Pt-Fe electrode in acid electrolyte was one and half times higher than that of Pt electrode(~500mA/$\textrm{cm}^2$ at 0.7VvsNHE).

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2002.11a
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• pp.333.1-333
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• 2002

This paper suggests the noise reduction method of the engine cooling fan. It was estimated the fannoise contribution at the engine room and identified the noise source at the rotating fan by sound intensity method, first. And it has been developed the program for predicting the noise spectrum of axial flow fan. The radiated acoustic pressure is expressed the discrete frequency noise peaks at BPF and its harmonics and the line spectrum at the broad band by the noise generation mechanisms. In this paper it is shown that the comparison of the measuted and calculaed noise spectra of fn for the validation of the noise predictiong program. And this paper presents the characteristics of a fan noise due to modify the design parameters. Accordingly, it was obtained the design parameter values for noise reduction of fan.