• Proceedings of the KIPE Conference
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• 2001.07a
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• pp.467-470
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• 2001

Power electronic converters generate the harmonic voltage and current, and these harmonics have the harmful effects on the various components. For example, passive components such as capacitor and inductor, transformer, motor and other components are mainly affected in the power electronic system. Thus, the design and manufacturing of the power converters, which have the harmonic-free or mitigation strategies, are required. In particular, the lifetime and durability of these components are main requirement for enhancing the overall stability of the system. So, in this paper, the harmonics-related problems to the neighbouring components and mitigation research trends are presented.

• Advances in aircraft and spacecraft science
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• v.5 no.6
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• pp.653-669
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• 2018

This work has the objective to analyze multibody mechanisms of inflatable structures for manned space applications. The focus is on the evaluation of the main characteristics of MaxFlex, a new module of MSC Adams including the effect of nonlinear flexible bodies. MaxFlex integrates the nonlinear Finite Element Analysis (FEA) of Nastran-SOL400-and the Adams multibody capabilities in one unique solver, providing an improvement concerning the concept and technology based on the co-simulation among solvers. MaxFlex converts the equations of motion of the nonlinear FEA into phase-space form and discretizes them according to the multibody system integrator framework. The numerical results deal with an inflatable manned space module having rigid components and a flexible coating made of Kevlar. This paper is a preliminary assessment of the computational capabilities of the software and does not provide realistic guidelines for the actual design of the structure. The analysis leads to some recommendations related to the main issues to consider in a nonlinear simulation including both rigid and flexible components. The results underline the importance of realistic deployment times and applied forces. Also, a proper structural modeling is necessary, but can lead to excessive computational overheads.

• Journal of the Korean Society of Tobacco Science
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• v.19 no.2
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• pp.124-128
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• 1997

Semivolatile components in mainstream smoke of cigarette attached the different type filter were analysed. Based on the main peak of GC profile, benzene, toluene, acetic acid, limonene, acetamide, pyridine, nicotine, phenol, pyrrole, and furfuryl alcohol were identified. The amount delivered of semivolatile components by each filter was evaluated with the ratio of areas of sample vs area% of ISTD. By comparing dual and triple filter to mono filter, the delivery amounts were 52% benzene, 62% toluene and 74% benzene, 84% toluene, respectively. The delivery amount of limonene which was known of tobacco taste component, were 52%, and 93% by dual and triple filter, respectively. Also, delivery amounts of acetic acid which was one of acidic compounds in smoke, were 86% and 83% by dual and triple filter, respectively. When adding the same amount of active carbon, the amounts delivered of vapour phase such as benzene and toluene by dual filter were lower than that of triple filter. But the delivery amounts of acetic acid and phenol by dual filter were higher than that of triple filter. This results assume that the pH of active carbon in filter affect to the adsorption or absorption of triacetin during filter making process.

• Analytical Science and Technology
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• v.8 no.4
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• pp.739-744
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• 1995

The two main methods to prepare water samples for analyzing volatile organic compounds(VOC's) were investigated. One is the purge and trap(PT) method and another is the head space(HS) sampling method. Both methods were effective to transfer the low boiling point components from the water sample onto the capillary column. The cryo-focusing at the top of the main capillary column was an effective way to obtain the sharpness of the chromatographic peaks but could be avoided when a semi-wide bore column was used. The recovery from the same amount of the sample was better in PT than in HS but a larger sample volume in HS method could compensate the lower efficiency. Therefore PT is suitable to the analysis of drinking water where the very low concentration must be determined. HS is suitable to waste water analysis because of the easiness of the operation. The repeatability was good and similar in both methods. For the contamination of the former sample, both methods were tough and could be used without any problems. The matrix effect which could change the equilibrium parameters in HS method was find negligible in many components. The actual samples such as tap water and river water were analyzed with both methods concerning 16 components regulated in Korea.

• Nuclear Engineering and Technology
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• v.50 no.1
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• pp.88-96
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• 2018

Concerns over reliability assessments of the main components in nuclear power plants (NPPs) related to aging and continuous operation have increased. The conventional reliability assessment for main components uses experimental correlations under general conditions. Most NPPs have been operating in Korea for a long time, and it is predictable that NPPs operating for the same number of years would show varying extent of aging and degradation. The conventional reliability assessment does not adequately reflect the characteristics of an individual plant. Therefore, the reliability of individual components and an individual plant was estimated according to operating data and conditions. It is essential to reflect aging as a characteristic of individual NPPs, and this is performed through prognostics. To handle this difficulty, in this paper, the general path model/Bayes, a data-based prognostic method, was used to update the reliability estimated from the generic database. As a case study, the authors consider the aging for steam generator tubes in NPPs and demonstrate the suggested methodology with data obtained from the probabilistic algorithm for the steam generator tube assessment program.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.19 no.12
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• pp.56-61
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• 2020

Fuel economy has always been a major issue in the automobile industry, especially owing to the associated environmental concerns. It is widely known that only 5-20% of the energy generated by automobiles running on internal combustion engine engines is used as power, while the rest is consumed because of friction between components. The main components of the reciprocating piston type compressor used in vehicles, such as the shaft, swash plate, piston, and cylinder, cause severe energy loss owing to frictional contact between each other. The wear contact between the main shaft and the other components is particularly severe. Most quality issues arise owing to the sticking phenomenon that occurs between these parts. In this study, a coating solution to reduce friction is prepared by mixing adhesive solid lubricant, organic binder-polyadimide, inorganic binder (Binder), and graphite in four different ratios, and the best combination is determined.

• Nuclear Engineering and Technology
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• v.55 no.11
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• pp.4266-4273
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• 2023

In a severe reactor accident, a crust will form on the surface of the molten material during the core melting process. The crust will have a contact melting with the internal components of the reactor. In this paper, the contact melting process of the molten material on the austenitic stainless steel plate bundles is studied. The contact melting model of parabolic molten material on the plate bundles is proposed, and the rule and main effect factors of the contact melting are analyzed. The results show that the melting velocity is proportional to the slope of the paraboloid, the heat flux and the distance between two plates D. The influence of melt gravity and the plate width on melting velocity is negligible. The thickness of the molten liquid film is proportional to the heat flux and plate width, and it is inversely proportional to the gravity. With the increase of D, the liquid film thickness decreases at first and then increases gradually. The liquid film thickness has a minimum against D. When the width of the plate is small, the width of the plate is the main factor affecting the thickness of the liquid film. The parameters are coupled with each other. In a severe reactor accident, the wider internal components of reactor, which can increase the thickness of the melting liquid film and reduce the net input heat flux from the molten material to the components, are the effective measures to delay the melting process.

• Journal of Electrical Engineering and Technology
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• v.10 no.4
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• pp.1422-1431
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• 2015

The reliability of power system components can be affected by a numbers of factors such as the health level of components, external environment and operation environment of power systems. These factors also affect the electrical parameters of power system components for example the thermal capacity of a transmission element. The relationship of component reliability and power system is, therefore, a complex nonlinear function related to the above-mentioned factors. Traditional approaches for reliability assessment of power systems do not take the influence of these factors into account. The assessment results could not, therefore, reflect the short-term trend of the system reliability performance considering the influence of the key factors and provide the system dispatchers with enough information to make decent operational decisions. This paper discusses some of these important operational issues from the perspective of power system reliability. The discussions include operational reliability of power systems, reliability influence models for main performance parameters of components, time-varying reliability models of components, and a reliability assessment algorithm for power system operations considering the time-varying characteristic of various parameters. The significance of these discussions and applications of the proposed techniques are illustrated by case study results using the IEEE-RTS.

• Journal of the Korean Institute of Navigation
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• v.25 no.4
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• pp.477-486
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• 2001

Although the ports are actually competing with various strategies, the definition and structural understanding of port competitive power are not known very much. Therefore this study has launched from this fact, and has the objective of obtaining the structural model of the competitive power, and understanding the components of the port competitive power. The following are the results of the study. First, the process began by abstracting the components that composed the port competitive power through recent research, and grouping it by the most core components using the KJ method. Also, by using the FSM(Fuzzy Structural Modeling) method to understand the structure of the grouped components, and the structural model of the port competitive power was able to obtain as the result. Second, when analyzing the obtained structural model, port expenses, main trunk location, port congestion and port facility came out to be the most important component groups, and especially port expenses was the most effective component that effected all the other components overall. Third, the component groups that were relatively less important, effected by most of the other components, and located on the top level of the structure model were the hinterland accessibility, port ownership, customs duties speed, and large ship port entrance possibility etc. Fourth, the results of this study will be able to be used when establishing competing strategies for our country's ports by proposing the relatively important components with the port competitive rower considered.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.07a
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• pp.135-138
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• 2002

VCO(Voltage Controlled Oscillator) is one of the main components governing the size, performance and power consumption of telecommunication devices. As the devices become much smaller, VCO need to have much smaller size with better characteristics. Buried type passive components of L,C,R were developed previously and the structure of these components are good for minimizing the size of VCO. Our own library of passive components is used in simulation and fabrication of VCO circuit, and surface mounted components like varactor diode are analysed using the measurement circuit designed by ourselves. Two-Dimensional simulation of VCO circuit and local three-Dimensional structure simulation are performed and their relation is obtained. In structure of multi-layered VCO, some components governing the characteristics of VCO are selected and placed on the top of oscillator for the good tuning process. In resonator part, the stripline structure and low loss glass/ceramic material are used to get higher Q value. In our research, a VCO oscillates in the 2.3∼2.36 GHz band is developed.