• Journal of Mechanical Science and Technology
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• 제14권9호
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• pp.928-934
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• 2000

This paper describes a method developed for the simulation of ring pack lubrication characteristic in an internal combustion engine. In general, the quantity of oil supply for piston ring lubrication may be insufficient in filling the entire volume formed at the interference between the piston ring and the cylinder liner. Thus the oil starvation condition should be considered in analyzing piston ring lubrication. In order to reasonably estimate the amount of oil left over on the cylinder liner, the flow rate at the posterior portion of the interface should be calculated with an adequate boundary condition that confirms flow continuity condition. In this analysis, oil starvation and open-end boundary conditions are considered at the inlet and outlet of the piston rings. The lubrication characteristic of each piston ring is obtained by an iterative method with sequential steps. It is revealed that piston rings are operated under oil starvation in most operating cycles and the result under these conditions are quite different from that with the fully-flooded assumption.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 한국정밀공학회 1995년도 추계학술대회 논문집
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• pp.365-368
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• 1995

Rotary Compressor has many AE(Acoustic Emission) sources according to condition of parts because it is operated with combination of various parts. In this study, analysis of AE raw signal generated form Rotary compressor which artificially-made parts inflicted abnormal condition was carried out. AE raw signals were acquired form high-speed A/D board, and many burst type signals were observed. By analyzing burst type signals which is caused form internal AE source,efficient AE parameters for monitoring and diagnosis were presented.

• International Journal of Highway Engineering
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• 제6권4호
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• pp.55-63
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• 2004

It is necessary to use the pavement condition index which evaluates the conditions of pavement objectively and is utilized for effective pavement management. PSI, MCI, UPCI are currently used indices, however, they do not play a role as general indices due to their unfair considerations only for users or managers. Thus, this paper pointed out the problems of current indices and developed a new pavement condition index. Also, a sensitivity analysis on the material properties was conducted for the proposed index using the real data obtained from fields. The material properties affected the index in order of surface thickness, asphalt viscosity and asphalt content.

• Journal of Institute of Control, Robotics and Systems
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• 제11권11호
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• pp.895-900
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• 2005

We derive a linear matrix inequality(LMI) condition guaranteeing that any invariant zeros of a triple (A, B, C) lie in the open left half plane of the complex plane, i.e. $C(sI-A)^{-1}B$ is minimum phase. The LMI condition is equivalent to a certain constrained Lyapunov matrix equation which can be found in many results relating to stability analysis or control design. We show that the LMI condition can be used to simplify various control engineering problems such as a dynamic output feedback control problem, a variable structure static output feedback control problem, and a nonlinear system observer design problem. Finally, we give some numerical examples.

• The Transactions of The Korean Institute of Electrical Engineers
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• 제64권2호
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• pp.331-337
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• 2015

The power flow analysis of electrified railway is required complicated calculation, because of variable load. Train runs trough rail supplied by electric power therefore, the load value in electrified railway system fluctuates along time. The power flow algorithm in electrified railway system is different from general power system, and the power flow simulation is peformed by the particular simulation software. Powerail is simulation software for analysis of traction power supply system developed by KRRI, in 2008. This consists of load forecasting module, including TPS and time scheduling, and power flow module. This software was verified by measured current under normal feeding condition, however, has not been verified by voltage on the condition of extended feeding. This paper presents the verification of PowerRail based on voltage drop under extended feeding condition. This is performed by comparing simulation result with field test. Field test and simulation is done in commercial railway line.

• Proceedings of the KSR Conference
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• 한국철도학회 2005년도 춘계학술대회 논문집
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• pp.14-19
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• 2005

An accelerated life test (ALT) is used to estimate the reliability of machinery parts and system with a design specification as soon as possible. However, accelerated life test results with simple and severe conditions are inconsistent with physical phenomena in real service condition. Therefore, to assure the safety of the machinery system, it is necessary to establish the appropriate test condition of the ALT of machinery element. In this study, fatigue analysis of the spur gear as a part of the gear box system in the rolling stock was performed. Moreover, based on the results, appropriate test condition of the ALT is developed using both the probabilistic model of the linear damage rule and accelerated durability analysis simulation.

• Proceedings of the KSR Conference
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• 한국철도학회 2010년도 춘계학술대회 논문집
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• pp.942-946
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• 2010

As the major sources of interior noise of train at running condition are the wheel/rail contact noise, the traction motor's noise and the driving gear's noise and these noise sources are transmitted through the car body, the noises of HVAC and air duct can be ignored. But the interior noise of train at standstill condition is decided by HVAC's noise and noise from the diffuser through the air duct. the interior noise prediction of train at standstill condition should be performed considering the shape of air duct, the air velocity and noise reduction property inside the air duct. But it is hard to estimate the interior noise level by the numerical method. Therefore train maker predict the interior noise level using The commercial noise prediction program. This paper introduce the noise prediction method of the train at standstill condition using the commercial program appling the ray tracing method and statistical energy analysis.

• Journal of the Korean Society for Precision Engineering
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• 제28권8호
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• pp.894-903
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• 2011

In this paper, the capability index is introduced in order to improve the reliability of new concept machine tools and the method to improve the machine accuracy from the analysis of cutting process, statistical methodology and influence factors are proposed. In addition, the rib structure of bed and column in machine tools is analyzed by using the thermal impact method in order to analogize the rib pattern which has the small thermal deformation under thermal boundary condition. In the analysis of column rib structure, thermal boundary condition is separated to heat conduction and heat transfer to appropriate real boundary condition. Finally, performance chart of bed and column rib structure is provided for designer to estimate each rib pattern and select rib structure appropriating to thermal condition.

• KSTLE International Journal
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• 제3권1호
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• pp.54-59
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• 2002

It can be effective on failure diagnosis of oil-lubricated tribological system to analyze operating conditions with morphological characteristics of wear debris in a lubricated machine. And it can be recognized that results are processed threshold images of wear debris. But it is needed to analyse and identify a morphology of wear debris in order to predict and estimate a operating condition of the lubricated machine. If the morphological characteristics of wear debris are identified by the computer image analysis and the neural network, it is possible to recognize the friction condition. In this study, wear debris in the lubricating oil are extracted from membrane filter (0.45 ${\mu}m$) and the quantitative value fur shape parameters of wear debris was calculated through the computer image processing. Four shape parameters were investigated and friction condition was recognized very well by the neural network.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2009년도 추계학술대회 논문집
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• pp.614-618
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• 2009

The effects of design parameters for small scale hydro power(SSHP) plants due to rainfall condition have been studied. The model to predict hydrologic performance for SSHP plants is used in this study. The results from analysis for rainfall conditions based on KIER model show that the capacity and load factor of SSHP site had large difference between the period. Especially, the hydrologic performance of SSHP site such as design flowrate due to rainfall condition of recent period varied sensitively. And also, the methodology represented in this study can be used to decide the primary design specifications of SSHP sites.