• The Transactions of the Korean Institute of Electrical Engineers D
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• v.55 no.3
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• pp.115-118
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• 2006

In the steel industry, a steel melting electric arc furnace is used to produce both carbon and alloy steels. Steel scrap which is charged into the furnace is heated by means of electric arc between graphite electrodes and the scrap. In this melting process, current is supplied to the furnace through HCC(high current cable) which connect the furnace and transformer. Four HCCs are assigned to each phase in our system to divide the current. Since a sudden cable breaking result in the shutdown of melting process, an aging detection of HCC is very important for both an improvement of productivity and cost reduction. In this paper, the aging of the HCC is estimated by using the current ratio between four HCCs.

• Proceedings of the KIEE Conference
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• 2015.07a
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• pp.331-332
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• 2015

Since $20^{th}$ century, along with the rapid industrial advancement, the concentrated urban development in specific large cities have made people migrate to those cities, thus causing problems in the power system stability. In case of Korea, more than 40% of the power system demand comes from the consumers in Seoul Metropolitan area and the rate is expected to increase. With the continuous increase of power demand, in order to meet the demand for system reliability improvement, the power system was multi-looped for reliability enhancement, the problem of fault current happened. In this situation, there are several methods for fault current reduction likes current limiting reactor, replacing circuit breaker, splitting busses, etc. But these methods reached its limit, power system needs more fundamental solutions such as grid segmentation. In this paper, we assume grid segmentation already has been progressed using VSC BTB HVDC. Then, this paper discusses operating point of HVDC in metropolitan area considering loss minimization and handy flow control. The simulation is proceeded on 2027 KEPCO system.

• Proceedings of the KIEE Conference
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• 2006.05a
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• pp.63-65
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• 2006

A electrical fault is defined as any abnormal condition caused by a reduction in the insulation strength. To define the potential risk of the electric installation, measurement of leakage current has been getting considered, but because the measured leakage current value also contained leakage current by capacitance, the measured value could not be adapted to absolute reference to the installation. Therefore, in this paper, the correlation between the condition of electric installation and leakage current were analyzed. The result focuses on to detect them in a cost efficient way.

• The KIPS Transactions:PartA
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• v.8A no.4
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• pp.319-330
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• 2001

In virtual memory system, when a process attempts to access a page that is not resident in memory, the system generates and handles a page fault that causes unpredictable delay. So virtual memory system is not appropriate for the real-time system, because it can increase the deadline miss ratio of real-time task. In multimedia system, virtual memory system may degrade the QoS(quality of service) of multimedia application. Furthermore, in general-purpose operating system, whenever a new task is dynamically loaded, virtual memory system suffers from extensive page fault that cause transient overloading state. In this paper, we present efficient overloading control mechanism called RBPFH (Rate-Based Page Fault Handling). A significant feature of the RBPFH algorithm is page fault dispersion that keeps page fault ratio from exceeding available bound by monitoring current system resources. Furthermore, whenever the amount of available system resource is changed, the RBPFH algorithm dynamically adjusts the page fault handling rate. The RBPFH algorithm is implemented in the Linux operating system and its performance measured. The results demonstrate RBPFH\`s superior performance in supporting multimedia applications. Experiment result shows that RBPFH could achieve 10%∼20% reduction in deadline miss ratio and 50%∼60% reduction in average delay.

• Proceedings of the KIEE Conference
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• 2015.07a
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• pp.153-154
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• 2015

Voltage Source Converter HVDC (VSC-HVDC) are a better alternative than conventional thyristor based HVDC systems. Unfortunately, VSC-HVDC's full potential cannot be utilized up till now due to absence of suitable HVDC protection. Recently, hybrid HVDC circuit breakers (HDCCB) have been developed and successfully lab tested. However, their application and feasibility in VSC-HVDC needs to be investigated. In this research paper we have modelled an existing HDCCB and evaluated its impact on fault reduction and interruption in VSC-HVDC systems. The HDCCB was applied in Korean Jeju-Haenam VSC-HVDC system model and its impact was analyzed for HVDC line-to-ground and line-to-line faults. HDCCB successfully interrupted the fault current and prevented the damages to costly IGBTs and converter transformers.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.55 no.4
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• pp.196-201
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• 2006

A electrical fault that may generate an electrical disaster is defined as any abnormal condition caused by reduction in the insulation strength. To find out the abnormal condition, periodical inspections have being performed every 3 years. Recently, the number of empty houses during normal working hours is rising by dramatic increase in the number of nuclear families and double income families. To define the potential risk of the electric installation, measurement of zero phase current has been being considered. But the measured value could not be adapted to an absolute reference to the installation because the measured zero phase current value also contained capacitive leakage current. Therefore, in this paper, the correlation between the condition of the electrical installation and the zero phase current was analyzed. The result focuses on to detect them in a cost efficient way.

• Proceedings of the KIEE Conference
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• 1995.07b
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• pp.500-502
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• 1995

Whenever faults(a fault) occur(s) in a particular section of a distribution system, some of loads get disconnected and are left unsupplied. Service should be restored to these affected load points as quickly as possible through network reconfiguration. An efficient technique is presented in this paper for this purpose. Network reduction and strategy testing the voltage and current constraints are the main contributions of this paper.

• Proceedings of the IEEK Conference
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• 2000.07a
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• pp.367-370
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• 2000

It is shown that $I_{DDQ}$ testing is very useful for shipping fault-free CMOS ICs. However, test time of $I_{DDQ}$ testing is extremely larger than one of logic testing. In this paper, a new test input sequence generation methodology is proposed to reduce the test time of $I_{DDQ}$ testing. At first, it is Shown that $I_{DDQ}$ test time Will be denominated by charge supply current for load capacitance of gates whose output logic values are changed by test input vector application and the charge current depends on input sequence of test vectors. After that, a test input sequence generation methodology is proposed. The feasibility is checked by some experiments.riments.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.53 no.2
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• pp.43-50
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• 2004

Percentage differential characteristic relaying(PDR) has been recognized as the principal basis for power transformer protection. Second harmonic restraint PDR has been widely used for magnetizing inrush in practice. Nowadays, relaying signals can contain 2nd harmonic component to a large extent even in a normal state, and 2nd harmonic ratio indicates a tendency of relative reduction because of the advancement of material. Further, as the power system voltage becomes higher and more underground cables are used, larger 2nd harmonic component in the differential current under internal fault is observed. And then, conventional 2nd harmonic restraint PDR exposes some doubt in reliability. It is, therefore, necessary to develop a new algorithm for performance improvement of conventional protective relaying. This paper proposes an advanced protective relaying algorithm by using voltage-current trend and flux-differential current slope characteristic. To evaluate the performance of the proposed algorithm, we have made comparative studies of PDR, fuzzy relaying and DWT relaying. The paper is constructed power system model including power transformer, utilizing the WatATP, and data collection is made through simulation of various internal faults and inrush. As the results of test, the new proposed algorithm was proven to be faster and more reliable.

• Health Policy and Management
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• v.2 no.1
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• pp.80-114
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• 1992

Current compensation schemes for medical malpractice based on negligence is absolutely malfunctioning in Korea. Focussing on the reform of present tort systems for resolving medical malpractice disputes, this paper discusses the alternative models of the Social Relief Schemes for Medical Malpractice (SRSMM). Alternative models of SRSMM should fundamentally be based on either negligence or nofalult compensation principle. On the foundation of the previous relief principle, the SRSMM should be equupped with three major components-the preventio/reduction of the sharp increasing medical malpractice, the effective and efficient resolving process for malpractice disputes and the proper social financing scheme for compensation. The paper deals with pros and cons of the possible alternative models for reform centering on the three major components of the scheme. As conclusions, administrative arbitration machinaries and a compulsory fund for compensating the injured under the negligence principle are proposed to resolve the current problems Korea has faced.