• Proceedings of the KSME Conference
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• 2007.05b
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• pp.2038-2043
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• 2007

Analysis of the internal state of the blast furnace is needed to predict and control the operating condition. Especially, it is important to develop modeling of blast furnace for predicting cohesive zone because shape of cohesive zone influences on overall operating condition of blast furnace such as gas flow, temperature distribution and chemical reactions. Because many previous blast furnace models assumed cohesive zone to be fixed, they can't evaluate change of cohesive zone shape by operation condition such as PCR, blast condition and production rate. In this study, an axi-symmetric 2-dimensional steady state model is proposed to simulate blast furnace process using the general purpose-simulation code. And Porous media is assumed for the gas flow and the potential flow for the solid flow. Velocity, pressure and temperature distribution for gas and solid are displayed as the simulation results. The cohesive zones are figured in 3 different operating conditions.

• 제어로봇시스템학회:학술대회논문집
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• 1997.10a
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• pp.1520-1523
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• 1997

A rigorous dynamic simulation was performed in binary gas mixture H$_{2}$/CO (70:30 vol.%) to determinate start-up operating conditions of PSA(Pressure Swing Adsorption) processes. The rigorous dynamic model for the PSA process contains an Ergun equation for expressing the pressure drop in a bed, and valve equations to compute the boundary pressure change of the bed. As the result of the continuous dynamic simulation of 100 operating cyles in various initial conditions, the unsteady-state appeared in the early period and the cyclic steady-state came out about 20th cycle in feed condition and vaccum condition, and 30th cycle in pure H$_{2}$ condition. As time goes by valve equations made change the pressure at each end of the bed in ressurization, countercurrunt-depressurization and pressure equalization steps. The H$_{2}$ purity and the recovery is 99.99% and 86.73% respectively, which is slightly higher than the experimental data. Main contributiion of this study includes supplying fundamental technologies of handling combined variables PSA processes by developing rigorous models.

• Proceedings of the KIPE Conference
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• 2016.07a
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• pp.231-232
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• 2016

This paper investigates the design of multi-winding coupled inductor for minimum inductor current ripple. Based on the general circuit model of coupled inductor together with the operating principles of dc-dc converter, the relationship between the ripple size of inductor current and the coupling factor is derived under the different duty ratio. The optimal coupling factor of n-phase multi-winding coupled inductor which corresponds to a minimum inductor ripple current becomes -(1/n-1), i.e. a complete inverse coupling without leakage inductance, as the duty ratio of steady-state operating point approaches 1/n, 2/n, ${\cdots}$ or (n-1)/n. In an opposite manner, the optimal coupling factor value of zero, i.e. zero mutual inductance, is required when the duty ratio of steady-state operating point approaches either zero or one. Therefore, coupled inductors having optimal coupling factor can minimize the ripple current of inductor and inductor size.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.26 no.8
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• pp.27-34
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• 2012

This paper proposes variable incremental conductance(IC) algorithm for maximum power point tracking(MPPT) control of photovoltaic. The conventional perturbation & observation(PO) and IC MPPT control algorithm generally uses fixed step size. A small step size reduces a tracking error in the steady state but slows a tracking speed in the transient state. Also, a large step size is fast a tracking speed but increases a tracking error. Therefore, this paper proposes variable IC MPPT algorithm that adjust automatically step size according to operating conditions. To improve a tracking speed and accuracy, when operating point is far from the maximum power point(MPP), the step size uses maximum value and when a operating point is near from the MPP, the step size uses variable step size that adjust according to slope of P-V curve. The validity of MPPT algorithm proposed in this paper prove through compare with conventional PO and IC MPPT algorithm.

• Journal of Biosystems Engineering
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• v.33 no.5
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• pp.333-339
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• 2008

The purpose of this study was to develop a portable electronic nose system to measure volatile components of agricultural and food products. Also, a graphical operating software to control the electronic nose system and to acquire signals through the Internet was developed. An array of five commercial metal oxide gas sensors was used to detect various volatile gas components of target samples. Transient and steady state signals were analyzed to extract variables related to sample states, To find optimal operating conditions of the system, several experiments were performed with different gas chambers, vacuum pumps, gas sampling temperatures, and sample container sizes. The patterns of gas sensor signals were analysed to find effects of the various conditions.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2000.10a
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• pp.36-39
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• 2000

This paper presents the technology of condition diagnosis & life estimation on insulation system of the traction motor. In the non-destructive methods for diagnosis of coil insulation state, residual dielectric strength is estimated by the D-map which consist of the partial discharge quantity Q and average degradation degree $\Delta$. In the operating history of machine, the N-Y life estimation method is based on the stop-starting numbers and operating times with considering each degradation factor by the thermal, electrical and heat-cycle stress. With the on-line conditioning monitoring on the currents of traction motors, detecting the abnormal operating state due to bearing faults, stator or armature faults, eccentricity related faults and broken rotor bars can be performed.

• KIEE International Transaction on Electrical Machinery and Energy Conversion Systems
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• v.3B no.3
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• pp.139-146
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• 2003

In this paper, the steady-state operating performance analysis for the three-phase squirrel cage rotor self-excited induction generator (SEIG) driven by a variable-speed prime mover (VSPM) in addition to a constant-speed prime mover (CSPM) is presented on the basis of an effective algorithm based on its frequency-domain equivalent circuit. The operating characteristics of the three-phase SEIG coupled by a VSPM and/or a CSPM are evaluated on line processing under the condition of the electrical passive load parameters variations with simple and efficient computation processing procedure in unregulated voltage control loop scheme. A three-phase SEIG prototype setup with a VSPM as well as a CSPM is implemented for the small-scale clean renewable and alternative energy utilizations. The experimental operating characteristic results are illustrated and give good agreements with the simulation ones.

• Proceedings of the KIPE Conference
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• 2017.07a
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• pp.88-89
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• 2017

This paper investigates the design of multi-winding coupled inductor for minimum inductor current ripple in rapid traction battery charger systems. Based on the general circuit model of multi-winding coupled inductor together with the operating principles of dc-dc converter, the relationship between the ripple size of inductor current and the coupling factor is derived under the different duty ratio. The optimal coupling factor which corresponds to a minimum inductor ripple current becomes -(1/n-1), i.e. a complete inverse coupling without leakage inductance, as the steady-state duty ratio operating point approaches 1/n, 2/n, … or (n1)/n. In an opposite manner, the optimal coupling factor value of zero, i.e. zero mutual inductance, is required when the steady-state duty ratio operating point approaches either zero or one.

• Proceedings of the KIPE Conference
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• 2015.07a
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• pp.195-196
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• 2015

This paper investigates the design of coupled inductor for minimum inductor current ripple in rapid traction battery charger systems. Based on the general circuit model of coupled inductor together with the operating principles of dc-dc converter, the relationship between the ripple size of inductor current and the coupling factor is derived under the different duty ratio. The optimal coupling factor which corresponds to a minimum inductor ripple current becomes -0.5, i.e. a complete inverse coupling without leakage inductance, as the steady-state duty ratio operating point approaches 1/3 or 2/3. In an opposite manner, the optimal coupling factor value of zero, i.e. zero mutual inductance, is required when the steady-state duty ratio operating point approaches either zero or one. Coupled inductors having optimal coupling factor can minimize the ripple current of inductor and battery current resulting in a reliable and efficient operation of battery chargers.

• The KIPS Transactions:PartA
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• v.11A no.4
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• pp.227-234
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• 2004

A panic state is often caused by careless computer control. It could be also caused by a kernel programmer's mistake. When panic is occurred, the process of the panic state has to be checked, then if it can be restored, operating system restores it, but if not, operating system runs the panic function to stop the system in the kernel hardening O.S. To decide recovery of the process, the type of the panic for the present process should be checked. The value type and the address type have to restore the process. If the system process has a panic state, the system should be designed to shutdown hardening function in the Linux operating system.