• Proceedings of the Safety Management and Science Conference
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• 2004.11a
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• pp.153-164
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• 2004

The growing importance of product quality is becoming more and more daily apparent as we enter the age of globalization around the world. And the product safety is getting more focus as well as product quality. As a result, many domestic companies are putting a lot of emphasis on safety measures and management activities and these companies' products are mainly superior to other companies' product. When we separate the product quality procedure into 3 steps, i.e. quality secure-quality confirm-quality guarantee, of course the 1st step is the most important, but also 2nd step of product quality confirm process is important. And in mass production environment, sampling inspection is more desirable than the $100\;\%$ inspection procedure. As a part of globalization trend, KS system is also being revised and reestablished based on ISO, IEC, etc. which are based on international standard. Conventional KS sampling inspection standards were in many areas quite different from ISO sampling standards, only KS A 3102, 3104, 3151 are left and the rest become obsolete, and even the ones that are still around are planned to the gone step by step. It has been already 3 years since the new KS A ISO $2859-0\sim3$ sampling inspection process has been established which the abolition of the popular KS A 3101, KS A 3105, KS A 3109, yet the implementation rate is very slow. This study will attempt to analyze the new KS A ISO 2859-2 and KS A ISO 2859-3, and try to understand the difference as that the new standard can be easily understood and used widely among companies, by using examples. Our attempt is to help implement with the companies with active safety involvement but the final result can be spread among other companies as well in the near future.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.38C no.1
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• pp.1-11
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• 2013

Reducing the energy that consumed by tag is a key requirement for the wider acceptance of the active RFID systems that use battery constrained tags. When the reader is not interrogating, the active RFID standard protocols try to reduce energy consumption of tags by using sleep mode. On sleep mode tags is active by receiving a specific signals from reader, until tag receive a sleep mode command from the reader, a tag waste energy for remaining in RX mode. Overhearing is a state of a tag in which it wastes energy for maintaining active RX state while there is no frame destined to it. According to our analysis, the amount of energy consumed by a tag due to overhearing is several time larger than that consumed by the effective communication. We propose RANO(Reservation Aloha for No Overhearing) that is designed to inform a tag of its effective communication intervals to eliminate overhearing problem in active RFID communication. The performance of the proposed protocol was evaluated through the real world by changing the number of tags and size of data. The result of an experiment, the proposed protocol performed saving about 22 times less than the standard protocol did.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.49 no.5
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• pp.302-309
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• 2000

The tracking characteristics of silicone rubber degraded by accelerated outdoor exposure employing a weather-o-meter were investigated. The tracking test was performed according to ICE Publ.587 method but the concentration of conductive solution was two times higher than IEC standard in order to accelerate the tracking failure. The number of large effective scintillation and the current of high voltage circuit were measured simultaneously. It was shown that the number of effective scintillation had valuable information of the tracking degradation state of silicone rubber, while the average current between electrodes could not provide information enough for diagnosis. Based upon the experimental results, it could be said that the key factor accelerating tracking failure was not Joule heating by current but pyrolysis by burning of silicone rubber, and that reduction of contact angle was due to chain scission which resulted in the free radicals of low molecules.

• Proceedings of the KSR Conference
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• 2011.05a
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• pp.1195-1201
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• 2011

Since the release of safety standard IEC 61508 which defines functional safety of electronic safety-related systems, SIL(Safety Integrity Level) certification for railway systems has gained lots of attention lately. In this paper, we propose a new design technique of the computer board for train control systems with high reliability and safety. The board is designed with TMR(Triple Modular Redundancy) using a certified SIL3 Texas Instrument(TI)'s TMS570 MCU(Micro-Controller Unit) to guarantee safety and reliability. TMR for the control device is implemented on FPGA(Field Programmable Gate Array) which integrates a comparator, a CAN(Controller Area Network) communication module, built-in self-error checking, error discriminant function to improve the reliability of the board. Even if a malfunction of a processing module occurs, the safety control function based on the proposed technique lets the system operate properly by detecting and masking the malfunction. An RTOS (Real Time Operation System) called FreeRTOS is ported on the board so that reliable and stable operation and convenient software development can be provided.

• IEMEK Journal of Embedded Systems and Applications
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• v.2 no.3
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• pp.129-137
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• 2007

MPEG-4 FGS is one of scalable video coding schemes specified In ISO/IEC 14496-2 Amendment 2, and particularly standardized as a scheme for providing fine granular quality and temporal scalabilities. In this paper, we propose a sign-bit reduction technique in embedded bit-plane coding to enhance the coding efficiency of MPEG-4 FGS system. The general structure of the FGS system for the proposed scheme is based on the standard MPEG-4 FGS system. The proposed FGS enhancement-layer encoder takes as input the difference between the original DCT coefficient and the decision level of the quantizer instead of the difference between the original DCT coefficient and its reconstruction level. By this approach, the sign information of the enhancement-layer DCT coefficients can be the same as that of the base-layer ones at the same frequency index in DCT domain. Thus, overhead bits required for coding a lot of sign information of the enhancement-layer DCT coefficients in embedded bit-plane coding can be removed from the generated bitstream. It is shown by simulations that the proposed FGS coding system provides better coding performance, compared to the MPEG-4 FGS system in terms of compression efficiency.

• Journal of Korea Multimedia Society
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• v.20 no.8
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• pp.1338-1346
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• 2017

To achieve software quality and human-centred design for electronic ship navigation called e-navigation, an international guideline of software quality assurance and human-centred design was approved in 2015. Usability is a common goal of both software quality assurance and human-centred design as developing e-navigation system and software developments. Therefore, research is needed to evaluate the usability of e-navigation systems and software such as metrics that can use usability testing. This paper derives effectiveness metrics for e-Navigation usability testing based on international standards. The research method is to analyses and compares the effectiveness measurement and metrics in ISO 9241-11 for human-centered design and ISO/IEC 25022 and 25023 for software quality to find out measurements and metrics being defined commonly. The derived metrics are applied to Electronic Chart Display and Information System as a case study based on performance standard.

• Journal of Electrical Engineering and Technology
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• v.11 no.6
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• pp.1783-1786
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• 2016

The paper investigates the insulation properties of the supercritical $CO_2$ ($SCCO_2$) fluid as an insulating medium for electrical apparatuses. The insulating material is crucial for electrical apparatuses and $SF_6$ gas has been widely used for high power electrical apparatuses. There have been many research efforts to develop substituents for $SF_6$ gas because of high global warming potential. We obtained above 350 kV/mm insulation strength with 12.0 MPa $SCCO_2$. The positive and negative IEC standard pulses are applied between two 10 mm diameter spherical electrodes. The insulation strength of $SCCO_2$ is at least 2.5 times higher than that of $CO_2$ gas at 6.0MPa. The insulation strength of $SCCO_2$ fluid is about 10 times higher than that of $SF_6$ at 0.5MPa which is the ordinary operating pressure of electrical switchgears. Using the result, we expect that the time for switching and dielectric recovery could be reduced using $SCCO_2$ fluid as an insulating medium.

• The Transactions of the Korean Institute of Power Electronics
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• v.22 no.1
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• pp.82-88
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• 2017

This study proposes a new topology for the performance test of a valve consisting of a modular multilevel converter (MMC)-based static synchronous compensator (STATCOM). The conventional valve performance test equipment requires high-voltage AC source of several kV rating because the number of submodules to be tested in a valve should be at least six or eight. However, the power source of the proposed scheme is DC and not AC source. The DC power source voltage range of the proposed test circuit is from several volts to several tens of volts. Therefore, the size and cost for the performance test equipment can be reduced considerably compared with the conventional method. The proposed scheme satisfies the requirements of the IEC 62927 standard. Simulations are conducted for a valve of 50[MVA] MMC-based STATCOM. Experimental results with a scale-downed setup show the validity of the proposed performance test topology.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2007.11a
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• pp.195-197
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• 2007

This paper presents experimental results on the safety of persons due to a ground fault in 22.9 kV-Y distribution system In order to evaluate the touch voltages due to internal ground faults in a step down transformer based on the newly prescribed KS C IEC 60364 standard series, the verification tests in a 22.9 kV multi-grounded neutral system were carried out From the experimental results, it was found that there will be significant potential rise jeopardizing LV equipment insulation in case of separate grounding between HV and LV system and the effective measures against hazardous touch voltages due to a IN side ground fault in the common grounding system between HV and LV system are proposed. As a consequence, it was found that the equipotential bonding is an important prerequisite for the effectiveness of the protective measures for the safety of persons in the common ground system between 22.9 kV-Y and low-voltage grounding system.

• Journal of Ocean Engineering and Technology
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• v.28 no.4
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• pp.288-293
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• 2014

The IEC standard for onshore or offshore wind turbines requires additional dummy simulations (at least 5 s) for the transient responses due to initial conditions. An increase in the dummy time causes a considerable increase in the computational cost considering multiple design spirals with several thousand design load analysis cases. A time of 30 s is typically used in practical simulations for a wind turbine design with a fixed platform. However, 30 s may be insufficient for floating offshore wind turbines (FOWT) because the platforms have lower natural frequencies, and the transient responses will last much longer. In this paper, an initial condition application algorithm is implemented for WindHydro, and the appropriate dummy simulation time is investigated based on a series of dynamic simulations of a FOWT. As a result, it is found that more than 300 s is required for the platform to have stationary motion after the initial transient responses for the FOWT under the conditions considered.