• Proceedings of the Korean Society of Computer Information Conference
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• 2018.07a
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• pp.177-178
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• 2018

본 논문에서는 와전류 탐상시험을 이용하여 전력선의 절연상태 진단을 수행하였다. 전력선은 6~18 가닥의 선으로 이루어져 있는데 절연상태 변화를 위해 수산화나트륨으로 전력선의 부식을 유도하였으며, 18~27 시간으로 부식시간을 설정하여 시편을 구분하였다. 전력선의 인장력시험, 뒤틀림시험, 전자주사현미경 등을 통하여 물리적 특성을 검토하였으며, 또한 200~800[mV]의 전압에서 부식에 따른 와전류 특성을 조사하였다.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.06a
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• pp.212-213
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• 2008

This paper describes the analysis of the device characteristics of the NPT type 1200V Insulated gate Bipolar Transistor. In case of NPT type IGBT devices, optimized n-epi layer thickness and concentration is important to obtain low on-state voltage and breakdown voltage characteristics. In this paper, we analyzed on-state and off-state characteristics of NPT type IGBT. Breakdown voltage of designed IGBT was higher than 1200V when we optimized Field Limiting Ring structures. And also, on-state voltage characteristics was shown less then 2.5V at 25A of drain current.

• Journal of Electrical Engineering and Technology
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• v.11 no.1
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• pp.192-199
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• 2016

With changes in insulated defects, the environment, and so on, new partial discharge (PD) data are highly different from the original samples. It leads to a decrease in on-line recognition rate. The UHF signal and pulse current signal of four kinds of typical artificial defect models in gas insulated switchgear (GIS) are obtained simultaneously by experiment. The relationship map of ultra-high frequency (UHF) cumulative energy and its corresponding apparent discharge of four kinds of typical artificial defect models are plotted. UHF cumulative energy and its corresponding apparent discharge are used as inputs. The support vector machine (SVM) incremental method is constructed. Examples show that the PD SVM incremental method based on simulated annealing (SA) effectively speeds up the data update rate and improves the adaptability of the classifier compared with the original method, in that the total sample is constituted by the old and new data. The PD SVM incremental method is a better pattern recognition technology for PD on-line monitoring.

• KOREAN JOURNAL OF PACKAGING SCIENCE & TECHNOLOGY
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• v.29 no.1
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• pp.27-33
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• 2023

An optimized design of the transportation insulated box must be considered to control the thermal damage in order to maintain the fresh condition for temperature-sensitive medicine and frozen food safety. The inside temperature of the insulated box is a natural convection enclosure state, thermal stratification naturally occurs as time passes in case of with outside heat load. The latent heat material (LHM) placement inside the box maintains the target temperature of the product for temperature fluctuations during transport, and LHM application is a common and efficient method. In this work, inside temperature stratification in an insulated box depending on the LHM pack position is numerically simulated and experimented. The insulated box is made up of vacuum insulation panel (VIP), and LHM modules are placed over six faces inside the box, with the same weight. The temperature curves for 72 hrs as experiment results clearly show the temperature stratification in the upper, middle, and lower at the LHM melting time region. However, the temperature stratification state is uniformly changed in accordance with the condition of the upper and lower placement weight of the LHM pack. And also, the temperature uniformity by changed placement weight of LHM has an effect on maintaining time for target air temperature inside the box. These results provide information on the optimized design of the insulated box with LHM.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.25 no.4
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• pp.253-260
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• 2012

IGBT (insulated gate bipolar transistor) have received wide attention because of their high current conduction and good switching characteristics. To reduce the power loss of IGBT, the on state voltage drop should be lowered and the switching time should be shorted. However, there is Trade-off between the breakdown voltage and the on state voltage drop. To achieving good electrical characteristics, field stop IGBT (FS IGBT) is proposed. In this paper, 1,200 V planar gate non punch-through IGBT (planar gate NPT IGBT), planar gate FS IGBT and trench gate FS IGBT is designed and optimized. The simulation results are compared with each three structures. In results, we optain optimal design parameters and confirm excellence of trench gate FS IGBT. Experimental result by using medici, shows 40% improvement of on state voltage drop.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.32 no.5
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• pp.366-370
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• 2019

In this paper, a single N+ emitter trench gate-type insulated gate bipolar transistor (IGBT) device was studied using T-CAD, in order to achieve a low on-state voltage drop (Vce-sat) and high breakdown voltage, which would reduce power loss and device reliability. Using the simulation, the threshold voltage, breakdown voltage, and on-state voltage drop were studied as a function of the temperature, the length of time in the diffusion process (drive-in) after implant, and the trench gate depth. During the drive-in process, a $20^{\circ}C$ change in temperature from 1,000 to $1,160^{\circ}C$ over a 150 minute time frame resulted in a 1 to 4 V change in the threshold voltage and a 24 to 2.6 V change in the on-state voltage drop. As a result, a 0.5 um change in the trench depth of 3.5 to 7.5 um resulted in the breakdown voltage decreasing from 802 to 692 V.

• Steel and Composite Structures
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• v.15 no.6
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• pp.705-724
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• 2013

The behaviour of steel column at elevated temperature is significantly different than that at ambient temperature due to its changes in the mechanical properties with temperature. Reported literature suggests that steel column may become vulnerable when exposed to fire condition, since its strength and capacity decrease rapidly with temperature. The present study aims at investigating the lateral load resistance of non-insulated steel columns under fire exposure through finite element analysis. The studied parameters include moment-rotation behaviour, lateral load-deflection behaviour, stiffness and ductility of columns at different axial load levels. It was observed that when the temperature of the column was increased, there was a significant reduction in the lateral load and moment capacity of the non-insulated steel columns. Moreover, it was noted that the stiffness and ductility of steel columns decreased sharply with the increase in temperature, especially for temperatures above $400^{\circ}C$. In addition, the lateral load capacity and the moment capacity of columns were plotted against fire exposure time, which revealed that in fire conditions, the non-insulated steel columns experience substantial reduction in lateral load resistance within 15 minutes of fire exposure.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.07a
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• pp.292-295
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• 2002

In this work, transient characteristics of NPT(Non Punch Through)-IGBT(Insulated Gate Bipolar Transistor) have been studied with different temperatures analytically. Power losses are caused by heat generated in MIT-IGBT for steady state and transient state conditions. We therefore have focused on the analysis of excess carrier concentration and excess charge injected into N-drift layer with different temperatures and have obtained anode voltage drop during turn-off with lifetime of 2.4[${\mu}$s].

• KIEE International Transactions on Power Engineering
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• v.4A no.1
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• pp.33-41
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• 2004

Knowledge of partial discharge (PD) is important to accurately diagnose and predict the condition of insulation. The PD phenomenon is highly complex and seems to be random in its occurrence. This paper indicates the possible use of chaos theory for the recognition and distinction concerning PD signals. Chaos refers to a state where the predictive abilities of a systems future are lost and the system is rendered aperiodic. The analysis of PD using deterministic chaos comprises of the study of the basic system dynamics of the PD phenomenon. This involves the construction of the PD attractor in state space. The simulation results show that the variance of an orthogonal axis in an attractor of chaos theory increases according to the magnitude and the number of PDs. However, it is difficult to clearly identify the characteristics of the PDs. Thus, we calculated the magnitude on an orthogonal axis in an attractor using singular value decomposition (SVD) and principal component analysis (PCA) to extract the numerical characteristics. In this paper, we proposed the condition monitoring method for gas insulated switchgear (GIS) using SVD for efficient calculation of the variance. Thousands of simulations have proven the accuracy and effectiveness of the proposed algorithm.

• Nuclear Engineering and Technology
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• v.49 no.1
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• pp.209-215
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• 2017

Fast neutron irradiation was used to improve the switching speed of a 600-V nonpunch-through insulated gate bipolar transistor. Fast neutron irradiation was carried out at 30-MeV energy in doses of $1{\times}10^8n/cm^2$, $1{\times}10^9n/cm^2$, $1{\times}10^{10}n/cm^2$, and $1{\times}10^{11}n/cm^2$. Electrical characteristics such as current-voltage, forward on-state voltage drop, and switching speed of the device were analyzed and compared with those prior to irradiation. The on-state voltage drop of the initial devices prior to irradiation was 2.08 V, which increased to 2.10 V, 2.20 V, 2.3 V, and 2.4 V, respectively, depending on the irradiation dose. This effect arises because of the lattice defects generated by the fast neutrons. In particular, the turnoff delay time was reduced to 92 nanoseconds, 45% of that prior to irradiation, which means there is a substantial improvement in the switching speed of the device.