• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.61 no.11
• /
• pp.1732-1736
• /
• 2012

To increase speed up of train, in the field of catenary system, it is necessary to develop of new monitoring methods for dynamic interaction between pantograph and contact wire. Also, there is a need to develop technologies that constantly measure are from various railway structure such as uplift of contact wire, vibration of catenary, dynamic strain of contact line in tunnel. In this paper condition monitoring systems for dynamic performance of catenary systems in tunnel were proposed. An advanced method and results of field tests using high speed camera for monitoring of vertical upward movement of the grooved contact wire due to the force produced from the pantograph were presented. The proposed uplift measurement system of contact wire is expected to enhance precision of current collection quality performance assessment methods at high-speed lines.

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.57 no.2
• /
• pp.214-220
• /
• 2008

Most of converter system could obtain almost unity power factor and make input current sinusoidal waveform, but they have many problems, such as electromagnetic interference and switching losses caused by switching noise in main switch. To solve these problems in hard switching PFC converter, soft switching converter using a resonant between capacitor and inductor is invented In this paper, advantages and disadvantages of conventional ZVT(Zero-Voltage-Transition) soft switching converter using a auxiliary resonant circuit is discussed. Then Improved ZVT soft switching converter proposed. This improved ZVT converter's operation principal, specific property, design scheme of main are described. From Simulation and experiment results of conventional ZVT soft switching and improved ZVT soft switching converter with active snubber, characteristics of the converter are confirmed.

• Journal of Korean Institute of Industrial Engineers
• /
• v.22 no.1
• /
• pp.129-139
• /
• 1996

Fault tree analysis is NP-hard problem. In this paper, we present a method which reduces size of the fault tree by eliminating the irrelevant events. Irrelevant event is the event which has no contribution to the system failure. In a fault tree, the irrelevant events occur due to the existence of the replicated events. By investigating the structure of the replicated events we establish the conditions which characterize the irrelevant events. Based on these conditions we present the computational algorithm which eliminate the irrelevant events. Complexity of the algorithm is shown to be polynomial and so, this algorithm can be utilized efficiently in FTA.

• Proceedings of the KIEE Conference
• /
• 2015.07a
• /
• pp.559-560
• /
• 2015

본 논문에서는 송전선로재폐로에 대한 개념과 방식 및 전압별 재폐로 적용사례를 소개하고 345kV 송전선로보호반에 적용하고 있는 재폐로시스템과 현재 재페로시스템 검증시험법에 대한 소개와 본 논문에서 소개하고자 하는 재폐로시스템 검증장치를 기존방법과 비교하여 본 장치를 사용함으로써 얻을 수 있는 장점에 대해 서술하였다.

• Fibers and Polymers
• /
• v.4 no.4
• /
• pp.204-209
• /
• 2003

The effect of padding solution on the microwave heat dyeing of polyester fabric was studied extensively. Polyester fabrics were impregnated in aqueous urea solution and aqueous sodium chloride solution for 10 min and then dyed for 7 min by microwave apparatus (2450 MHz, 700 W) under optimum conditions which provide good exhaustion. Aqueous solutions of urea and sodium chloride showed more effective than water as a padding solution for microwave heat dyeing. The type of solvent added in padding media and its concentration significantly affects the K/S values of dyed polyester fabric. Added solvents such as n-hexane, acetone, and dimethyl formamide were also more effective than 100 % water as padding media for the microwave heat dyeing. It is supposed that the effect of used solvents on dyeing property of polyester fabrics depends on the solubility parameter difference between solvent and polyester fabric.

• Geomechanics and Engineering
• /
• v.16 no.2
• /
• pp.159-168
• /
• 2018

In this study, a real-time grouting management system based on the clogging theory was established to manage injection procedure in real time. This system is capable of estimating hydraulic permeability with the passage of time as the grout permeates through the ground, and therefore, capable of estimating real time injection distance and flow rate. By adopting the Controlled Injection Pressure (CoIP) model, it was feasible to predict the grout permeation status with the elapse of time by consecutively updating the hydraulic gradient and flow rate estimated from a clogging-induced alteration of pore volume. Moreover, a method to estimate the volume of the fractured gap according to the reduction in injection pressure was proposed. The validity of the proposed system was successfully established by comparing the estimated values with the measured field data.

• BMB Reports
• /
• v.34 no.4
• /
• pp.305-309
• /
• 2001

MatR in Rhizobium trifolii is a malonate-responsive transcription factor that regulates the expression of genes, matABC, enabling decarboxylation of malonyl-CoA into acetyl-CoA, synthesis of malonyl-CoA from malonate and CoA, and malonate transport. According to an analysis of the amino acid sequence homology, MatR belongs to the GntR family The proteins of this family have two-domain folds, the N-terminal helix-turn-helix DNA-binding domain and the C-terminal ligand-binding domain. In order to End the malonate binding site and amino acid residues that interact with RNA polymerase, a site-directed mutagenesis was performed. Analysis of the mutant MatR suggests that Arg-160 might be involved in malonate binding, whereas Arg-102 and Arg-174 are critical for the repression activity by interacting with RNA polymerase.

• Journal of Mechanical Science and Technology
• /
• v.16 no.4
• /
• pp.572-579
• /
• 2002

The experimental measurements were carried out to examine turbulent disintegration characteristics ejecting from a counter-flowing internal mixing pneumatic nozzle under variable conditions of swirl angles and air pressures. The air injection pressure was varied from 60 kPa to 180 kPa and four counter-flowing internal mixing nozzles with axi-symmetric tangential-drilled holes at swirl angle of 15$^{\circ}$, 30$^{\circ}$, 45$^{\circ}$, and 60$^{\circ}$to the central axis have been specially designed. The experimental results were quantitatively analyzed, focusing mainly on the comparison of turbulent atomization characteristics issuing from an internal mixing swirl nozzle. To illustrate the swirl phenomena, the distributions of mean velocities, turbulence intensities, volume flux, and SMD (Sauter Mean Diameter, or D$\sub$32/) were comparatively analyzed.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.24 no.9 s.180
• /
• pp.2174-2183
• /
• 2000

In this paper, the evaluation method of interfacial fracture toughness to apply the fracture toughness was investigated in adhesively bonded joints of AI/Ced./A1. Four types of adhesively bonded double-cantilever beam(DCB) joints with the interface crack were prepared for the test of interfacial fracture toughness. The experiments to measure the interfacial fracture toughness were performed under the various mixed-mode conditions. The critical energy release rate, Gc, was obtained by the experimental measurement of compliances. From the experimental results, the interfacial fracture toughness for the mixed-mode specimens is well characterized by the energy release rate, and the method of strength evaluation by the interfacial fracture toughness was discussed in adhesively bonded joints.

• 대한핵의학회:학술대회논문집
• /
• 2006.05a
• /
• pp.51-52
• /
• 2006