• The Journal of the Korea institute of electronic communication sciences
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• v.15 no.5
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• pp.791-798
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• 2020

The share of advanced technology in modern weapon systems are gradually increasing, and life cycle of components are shortened due to the rapid speed of technological development. On the other hand, the weapon systems have a characteristic that takes a long time in the requirement stage of weapon to the operation and maintenance stage. Due to inevitably, obsolescence of the main components for parts occurs in the acquisition phase. The obsolescence parts could cause delays in mass production schedules, and further adversely affects operational availability due to poor supply of repair parts during in the maintenance phase. However, business managers are obliged to maximize the performance while minimizing the cost of the total life cycle of the design, production, and operation stages. It is necessary to establish and implement an appropriate components and parts of life cycle management plan. In this research, we analyzed the effectiveness of parts obsolescence management through cost avoidance and total life cycle cost that can be reduced through proper parts obsolescence management.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.5
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• pp.257-265
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• 2020

Parts obsolescence is a component type, in which raw materials or parts that make up a weapons system, are developed and produced according to demand, but they age due to changes in technology or market conditions. The weapon system equipment currently being used by the military is having difficulty in procurement, maintenance, and operation because of the obsolescence of parts. Parts obsolescence during the life cycle of a weapons system affects not only the combat readiness of the military but also the economic loss of material, parts, and equipment manufacturers and suppliers. On the other hand, advanced technology has reduced the life span of electronic components that make up the weapons system. In addition, because of the nature of the weapons system, the obsolescence of components takes decades from development to disposal, which has a serious adverse effect on equipment readiness and life cycle costs. Therefore, it is necessary to manage systematically the parts obsolescence from development until the disposal of the weapons system equipment. This study examined the system of component control in developed countries to present a proper management plan for local situations and propose development plans for the early settlement of component control.

• Journal of the Korea Safety Management & Science
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• v.19 no.3
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• pp.97-107
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• 2017

This research studies on the demand forecasting for service parts considering parts life cycle, that gets relatively less attentions in the field of forecasting. Our goal is to develop forecasting method robust across many situations, not necessarily optimal for a limited number of specific situations. For this purpose, we first extensively analyze the drawbacks of the existing forecasting methods, then we propose the new demand forecasting method by using these findings and reinforcement leaning technique. Using simulation experiments, we proved that the proposed forecasting method is better than the existing methods under various experimental environments.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.22 no.2
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• pp.409-417
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• 2021

The standardization of weapon system parts is one of the elements of parts management and is an important factor for reducing the cost of acquiring and maintaining a weapon system, enhancing its reliability, improving interoperability, alleviating parts obsolescence problems, improving logistics efficiency, and strengthening the military's combat readiness. This study examined how to manage parts of domestic R&D weapon systems, overseas imports weapon system parts, and various commercial parts from a standardization perspective, and to study parts management methods for standardizing parts in the future. This system was used to achieve systematic part standardization in a military weapon system. To this end, this study investigated what elements are used to standardize weapon system parts. The importance and weight of each element were calculated using the AHP (Analytic Hierarchy Process), one of the decision-making techniques, and the design stage standards using the part selection method were studied. Through this, the selection process of standard parts, which has been made according to the experience and subjective judgment of designers and personnel, was improved to propose a systematic and objective method of standardizing weapons parts.

• Proceedings of the Korean Nuclear Society Conference
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• 1995.10a
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• pp.153-158
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• 1995

All of the nuclear power plants in Korea we operating with analog instrumentation and control (I&C) equipment which are increasingly faced with frequent troubles, obsolescence and high maintenance expenses. Electrical and computer technology has improved rapidly in recent years and has been applied to other industries. So it is strongly recommended we adopt modern digital and computer technology to improve plant safety and availability. The advanced I&C system, namely, Integrated Intelligent Instrumentation and Control System (I$^3$CS) will be developed for beyond the next generation nuclear power plant. I$^3$CS consists of three major parts, the advanced compact workstation, distributed digital control and protection system including Automatic Start-up/shutdown Intelligent Control System (ASICS) and the computer-based alarm processing and operator support system, namely, Diagnosis, Response, and operator Aid Management System (DREAMS).

• Proceedings of the KIPE Conference
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• 2018.07a
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• pp.177-179
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• 2018

After Fukushima nuclear accident at 2011, nuclear industrial has been focused on operation and maintenance phase, not design and construction phase. Continued good operating performance of nuclear power plants has been the best critical issue to nuclear utilities. Replacement for complete components as well as parts of components is being procured because nuclear utilities must maintain safety and reliability of operating nuclear power plants. However, many suppliers and manufacturers are giving up a nuclear quality assurance program under reduction in new construction of nuclear power plants. It is able to be increased difficulty in procuring spare parts to support operations and maintenance of nuclear power plants. Over 20% of nuclear power plant equipment in some countries is obsolete. Owing to obsolescence of nuclear safety-related items and/or withdrawing a nuclear quality assurance program of suppliers and manufactures, some replacement item and part might be procured to the item not covered by appendix B to USNRC 10 CFR Part 50. Under various methods of the nuclear repair and replacement methodology, utilities are supposed to establish a typical program for a repair and replacement of an electrical equipment and its parts in conjunction with a nuclear quality assurance. Concerning this typical program, this study suggests the repair and replacement methodology of electrical equipments used in nuclear power plants by procurement of a power supply, based on nuclear regulations, codes, standards, guidelines, specific and general technical information, etc..

• Nuclear Engineering and Technology
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• v.53 no.7
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• pp.2237-2250
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• 2021

The analog-based Ex-core Neutron Flux Monitoring System (ENFMS) in Korean Nuclear Power Plants (NPPs) has been performing its intended functions successfully for a long time. On the other hand, the primary concern with the extended use of analog systems is the aging effect, such as mechanical failures, environmental degradation, and obsolescence. The transition to a digital-based Man-Machine Interface Systems (MMIS) in Korea and other countries has been accelerating, but some systems are still analog-based IC systems, such as the ENFMS in APR1400 NPPs. Digitalized ENFMS can become a reality using computers and microprocessors owing to the progress in digital electronics and information technology. This paper presents the result of the first phase of the research on the digitalization of the ENFMS signal processing electronics for NPPs operated or produced in Korea. It has two main parts: (1) review engineering bases of ex-core neutron flux monitoring system, including nuclear engineering, instrumentation techniques, and analog and digital signal processing techniques, and (2) analysis of analog signal processing electronics of ENFMS for OPR1000 and APR1400 power plants. They are prerequisite to the second phase of the research which is the detailed implementation of the digitalization.

• Journal of architectural history
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• v.19 no.1
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• pp.27-50
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• 2010

This paper was to analyze the fusion between the organic and inorganic characteristics performed in architecture and urbanism, especially on the characteristics found in the works of Archigram group who was very active during 1960s and 70s. Generally, it was thought that Archigram drew its ideas mainly from a mechanist metaphor and that the diagrams of its members were based on the notion of the material obsolescence, which could be placed in a British tectonic tradition. But, Archigram's works has been continually influenced by the biological-organic analogy from the birth of the group to its dissolution. Simply, the importance that the biological-organic analogy takes in the works of Archigram has changed periodically according to the change of its members. We can divide generally Archigram group in two parts : on one hand, nascent members such as Peter Cook, Dennis Greene, Michael Webb ; on the another hand, three members who participated from LCC such as Warren Chalk, Ron Herron, Dennis Crompton. As the new three LCC members participated, Archigram Group focalized on the technological part more than ever. But, when its members dispersed geographically and professionally, its biological-organic analogy came out again at the surface of their works. However, Archigram's organic and inorganic characteristics did not always adhere in opposing position with each other and took the form of coexistence in harmony at the same period. That is, the works of Archigram were persuing the creation of community that nature, technology and architecture could communicate and harmonize with each other through the intergration between organic and inorganic characteristics. The reason why Archigram became the one of the most excellent architectural avant-garde group in the 60s was mainly to receive asssitance with the fact that two small groups having contradictory tendencies got together and formed the Archigram group.

• Applied Microscopy
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• v.38 no.2
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• pp.107-115
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• 2008

The filtration barrier of kidney consists of endothelial cell, glomerular capillary, glomerular basement membrane, mesangial matrix, and podocyte. In aged rats, the morphological changes were shown in various parts, including the glomerulus. These changes were thickening of basement membrane and mesangial matrix, crescent formation of glomerular capillary, deformity of foot processes, glomerular sclerosis and obsolescence. But these glomerular morphologies are partial images or few serial images analysis. In this study, we examined the morphological alteration of glomerulus in the young and aged rats by light microscopy, transmission electron microscopy and three dimensional reconstruction. We were found in aged rat glomerulus, expansion of urinary space and mesangial matrix, thickening and degrading of glomerular basement membrane, decreasing in podocyte foot processes, fragmentation of podocytic nucleus membrane. These observations indicate that may provide useful data for investigating the pathogenesis of age-related dysfunction of kidney.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.41 no.1
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• pp.50-58
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• 2018

Intermittent demand is a demand with a pattern in which zero demands occur frequently and non-zero demands occur sporadically. This type of demand mainly appears in spare parts with very low demand. Croston's method, which is an initiative intermittent demand forecasting method, estimates the average demand by separately estimating the size of non-zero demands and the interval between non-zero demands. Such smoothing type of forecasting methods can be suitable for mid-term or long-term demand forecasting because those provides the same demand forecasts during the forecasting horizon. However, the smoothing type of forecasting methods aims at short-term forecasting, so the estimated average forecast is a factor to decrease accuracy. In this paper, we propose a forecasting method to improve short-term accuracy by improving Croston's method for intermittent demand forecasting. The proposed forecasting method estimates both the non-zero demand size and the zero demands' interval separately, as in Croston's method, but the forecast at a future period adjusted by binomial weight according to occurrence probability. This serves to improve the accuracy of short-term forecasts. In this paper, we first prove the unbiasedness of the proposed method as an important attribute in forecasting. The performance of the proposed method is compared with those of five existing forecasting methods via eight evaluation criteria. The simulation results show that the proposed forecasting method is superior to other methods in terms of all evaluation criteria in short-term forecasting regardless of average size and dispersion parameter of demands. However, the larger the average demand size and dispersion are, that is, the closer to continuous demand, the less the performance gap with other forecasting methods.