• 전자통신동향분석
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• 제14권4호통권58호
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• pp.1-9
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• 1999

In this paper, we summarize the lessons learned from the applications of the software reliability engineering to a large-scale software project. The considered software is the software system of the TDX-10 ISDN switching system. The considered software consists of many components, called functional blocks. These functional blocks serve as the unit of coding and test. The software is continuing to be developed by adding new functional blocks. We are mainly concerned with the analysis of the effects of these software components to software reliability and with the analysis of the reliability evolution. We analyze the static characteristics of the software related to software reliability using failure data collected during system test. We also discussed a pattern which represents a local and global growth of the software reliability as version evolves. To find the pattern of software of the TDX-10 ISDN system, we apply the S-shaped model to a collection of failure data sets of each evolutionary version and the Goel-Okumoto (G-O) model to a grouped overall failure data set. We expect this pattern analysis will be helpful to plan and manage necessary human/resources for a new similar software project which is developed under the same developing circumstances by estimating the total software failures with respect to its size and time.

• 센서학회지
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• 제24권5호
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• pp.326-330
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• 2015

The recent development of Sensor technology has broadened its applications to many fields of industry including railroad. The sensor technology enables the railroad system to monitor and control. This paper suggests the sensor based system design for evaluating and improving the reliability and safety of the ICT system. For this purpose, the reliability and the level of safety integrity of a general gateway have been predicted quantitatively and the supplementary design has been proposed for RAMS improvement. RAMS requirements for each life cycle stipulated in IEC 62278. RAMS activity is capable of producing significant and effective reductions in operation costs and time.

• Journal of Power Electronics
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• 제15권5호
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• pp.1149-1157
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• 2015

As a key part in the wind turbine system, the power electronic converter is proven to have high failure rates. At the same time, the failure of the wind power converter is becoming more unacceptable because of the quick growth in capacity, remote locations to reach, and strong impact to the power grid. As a result, the correct assessment of reliable performance for power electronics is a crucial and emerging need; the assessment is essential for design improvement, as well as for the extension of converter lifetime and reduction of energy cost. Unfortunately, there still exists a lack of suitable physic-of-failure based evaluation tools for a reliability assessment in power electronics. In this paper, an advanced tool structure which can acquire various reliability metrics of wind power converter is proposed. The tool is based on failure mechanisms in critical components of the system and mission profiles in wind turbines. Potential methodologies, challenges, and technology trends involved in this tool structure are also discussed. Finally, a simplified version of the tool is demonstrated on a wind power converter based on Double Fed Induction Generator system. With the proposed tool structure, more detailed information of reliability performances in a wind power converter can be obtained before the converter can actually fail in the field and many potential research topics can also be initiated.

• 한국전기전자재료학회논문지
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• 제36권3호
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• pp.214-225
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• 2023

Piezoelectric actuators, which utilize piezoelectric crystals or ceramics, are commonly used in precision positioning applications, offering high-speed response and precise control. However, the use of low-performance ceramics and expensive single crystals is limiting their versatile use in the actuator market, necessitating the development of both high-performance and cost-effective piezoelectric materials capable of delivering higher forces and displacements. The use of textured Pb (lead)-based piezoelectric ceramics formed by so-called templated grain growth method has been identified as a promising strategy to address the performance and cost issue. This review article provides insights into recent advances in texturing Pb-based piezoelectric ceramics for improved performance in actuation applications. We discussed the relevant issues in detail focusing on current challenges and emerging trends in the textured piezoelectric ceramics for their reliability and performance in actuator applications. We discussed in detail focusing on current challenges and emerging trends of textured piezoelectric ceramics for their reliability and performance in actuator applications. In conclusion, the article provides an outlook on the future direction of textured piezoelectric ceramics in actuator applications, highlighting the potential for further success in this field.

• 전자통신동향분석
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• 제36권6호
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• pp.13-24
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• 2021

Industrial networks has been developing various technologies from fieldbus technology to industrial Ethernet and time-sensitive networking. The industry expects that the 5G mobile network will solve the diverse and highly specific industrial site requirements. Accordingly, 3GPP has been developing standard functions to provide ultra-high reliability, ultra-high speed, ultra-connection, and ultra-low latency services, and 3GPP Rel-16 began developing ultra-low latency and ultra-high reliability communication functions for 5G mobile networks to support vertical industries. In this paper, we show the related standardization trends and requirements to apply industrial IoT service scenarios to 5G mobile networks, and in particular, we introduce 5G system features and extended 5G system architecture to provide time sensitive communication and time synchronization services.

• 소성∙가공
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• 제11권2호
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• pp.103-107
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• 2002

With the great demand for WDM (Wavelength Division Multiplexing) optical communications, optical switches are expected to become one of the dominant components in future networks. Conventional mechanical switches suffer from poor reliability and large size; however, many micromachined optical switches with moving mirrors have been proposed for high scale OXC (Optical Crossconnect) or ADM (Add/Drop Multiplex) because of the low power consumption and high reliability of these switches. In this paper, we introduce the technological trends of optical switches using MEMS, related micromachining technologies and their characteristics.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2005년도 춘계학술대회 논문집 전기설비전문위원
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• pp.10-12
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• 2005

This paper describes MV switchgear technology trends and diagnosis technology. MV switchgear has been rapidly changed into compact, reliability and safety situation. And suggested road-map to implement condition assessment or condition based maintenance. On-line diagnosis technology, life evaluation technology and system technology are suggested.

• Smart Structures and Systems
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• 제14권2호
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• pp.209-224
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• 2014

With more and more built long-term structural health monitoring (SHM) systems, it has been considered to apply monitored data to learn the reliability of bridges. In this paper, based on a long-term SHM system, especially in which the sensors were embedded from the beginning of the construction of the bridge, a method to calculate the localized reliability around an embedded sensor is recommended and implemented. In the reliability analysis, the probability distribution of loading can be the statistics of stress transferred from the monitored strain which covered the effects of both the live and dead loads directly, and it means that the mean value and deviation of loads are fully derived from the monitored data. The probability distribution of resistance may be the statistics of strength of the material of the bridge accordingly. With five years' monitored strains, the localized reliabilities around the monitoring sensors of a bridge were computed by the method. Further, the monitored stresses are classified into two time segments in one year period to count the loading probability distribution according to the local climate conditions, which helps us to learn the reliability in different time segments and their evolvement trends. The results show that reliabilities and their evolvement trends in different parts of the bridge are different though they are all reliable yet. The method recommended in this paper is feasible to learn the localized reliabilities revealed from monitored data of a long-term SHM system of bridges, which would help bridge engineers and managers to decide a bridge inspection or maintenance strategy.

• 전자통신동향분석
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• 제37권3호
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• pp.23-32
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• 2022

This paper provides an overview of optical transport technology for 5G mobile fronthaul. The configuration of fronthaul network is classified with dedicated fiber, passive WDM(Wavelength Division Multiplexing), active WDM, and semi-active WDM, which has its own advantages and drawbacks. Various WDM technology is applied for fronthaul transport, depending on the wavelength bands, required number of wavelength channels, configuration of fronthaul network, etc. In order to meet the increasing transport capacity, a 50/100 Gbps optical transceiver will be used in place of the present 10/25 Gbps technology. Trends will be continued to enhance the flexibility and reliability of the fronthaul optical network supporting highly advanced 5G mobile services.

• 한국전기전자재료학회논문지
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• 제32권5호
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• pp.371-375
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• 2019

Developing a thin-film transistor with characteristics such as a large area, high mobility, and high reliability are key elements required for the next generation on displays. In this paper, we have investigated the research trends related to improving the reliability of oxide-semiconductor-based thin-film transistors, which are the primary focus of study in the field of optical displays. It has been reported that thermal treatment in a high-pressure oxygen atmosphere reduces the threshold voltage shift from -7.1 V to -1.9 V under NBIS. Additionally, a device with a $SiO_2/Si_3N_4$ dual-structure has a lower threshold voltage (-0.82 V) under NBIS than a single-gate-insulator-based device (-11.6 V). The dual channel structure with different oxygen partial pressures was also confirmed to have a stable threshold voltage under NBIS. These can be considered for further study to improve the NBIS problem.