• Journal of the Korea Academia-Industrial cooperation Society
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• v.10 no.6
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• pp.1346-1352
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• 2009

Warranty cost of automobile parts varies depending on the parts failure rate in a warranty region of individual markets. Parts failure rate is significantly affected by usage-rate given that other stressors of individual markets are similar. Accordingly, warranty cost can be predicted by failure modeling which reflects usage-rate and using a stochastic process. In this paper, one-dimensional approach is used by applying accelerated failure time model on the assumption that the usage-rate is linear. Such model can explain changes in parts failure rate depending on the changes in usage-rate since it can be expressed as a function of usage-rate. Therefore, acquisition of usage-rate in a new market will automatically lead to estimate of failure rate even without warranty data and warranty cost of parts can be predicted through a renewal process in replacement cases. A case study using warranty data of two real markets is presented in the application part of this paper.

• Smart Media Journal
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• v.13 no.1
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• pp.18-23
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• 2024

Power efficiency management in smart farms is important due to its link to climate change. As climate change negatively impacts agriculture, future agriculture is expected to utilize smart farms to minimize climate impacts, but smart farms' power consumption may exacerbate the climate crisis due to the current electricity production system. Therefore, it is essential to efficiently manage and optimize the power usage of smart farms. In this study, we propose a system that monitors the power usage of smart farm equipment in real time and predicts the power usage one hour later using GRU. CT sensors are installed to collect power usage data, which are analyzed to detect and prevent abnormal patterns, and combined with IoT technology to efficiently manage and monitor the overall power usage. This helps to optimize power usage, improve energy efficiency, and reduce carbon emissions. The system is expected to improve not only the energy management of smart farms, but also the overall efficiency of energy use.

• Journal of the Korean Home Economics Association
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• v.42 no.2
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• pp.1-18
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• 2004

The purpose of this study was to investigate the degree of relationship satisfaction and self-disclosure in real-space friend relations and cyber-space friend relations. The sample was 248 middle and high school students, and 107 undergraduates. The main findings of this study are as follows: 1) Relationship satisfaction is significantly higher in cyber-space friend relations than in real-space friend relations. 2) In contrast to relationship satisfaction, self-disclosure is significantly higher in real-space friend relations than in cyber-space friend relations. 3) Self-disclosure differs significantly in terms of grade, gender, number of friends, communication method, and daily internet usage.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.27 no.3
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• pp.43-49
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• 2013

Recently harmonics flowing into power system is increasing as the usage of semiconductor equipments and switching mode power equipments are increasing. Harmonics cause problems such as heat increasing and reduction in capacity of transformers, especially the harmonics flowing into a distribution transformer can lead to the lifetime reduction of transformer. In this paper, we are about to develop a device that can monitor harmonics in real-time as it is affixed to a distribution transformer. Unlike the existing expensive harmonic analysis device, a new harmonic analysis algorithm is proposed in order to implement low-cost equipment. The real-time harmonic analysis algorithm proposed in this paper allows implementation on low performance microcontrollers, thus it can monitor the harmonic in real-time as it is individually affixed to the transformer. Therefore, it would improve the reliability of the transformer and stable power system operation would be possible as it can prevent the transformer accidents in advance.

• Proceedings of the Korea Society for Simulation Conference
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• 1998.03a
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• pp.27-31
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• 1998

The growing usage of multimedia communication applications with specific bandwidth and real-time delivery requirements has created the needs for quality of service(QoS). In response to the growing demand for an integrated services, the Reservation Protocol(RSVP) has been designed to exchange resource reservation among routers in the internet. RSVP protocol provides the quality of service for real-time applications but the network efficiency is reduced because of the limited bandwidth. In order to use network resources efficiently. We compare the resource efficiency of traditional reservation methods with that of the proposed method and evaluate the performance of the internet phone.

• Asia pacific journal of information systems
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• v.12 no.3
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• pp.89-113
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• 2002

As Mobile Internet users grow rapidly, Mobile Internet Companies will be in a fierce race to catch a new customer. In this situation, companies want to identify of what factors make peoples use Mobile Internet in order to develop the effective Mobile Internet services and to supply the higher service quality. However, prior researches on Mobile Internet focused on technical area such as higher data delivery, efficient compression of images, so they do not have given companies beneficial materials for making fascinating Mobile Internet service. To offer the service development materials, this research investigated important factors to use Mobile Internet from the viewpoint of customer. Moreover, the study was progressed how much these factors influenced Mobile Internet actual usage. After being surveyed service adopting model and significant factors in Marketing and in MIS(Management Information System), this study was suggested Mobile Internet Adopting Model reflected in Mobile Internet characteristics. To collect the effective data, Internet survey had been done for two weeks. The respondents were identified if they were real Mobile Internet users and how much they had used Mobile Internet for a month. The results were that important factors of Mobile Internet usage were Usefulness, Usability, System Quality and Instant Connectivity. Perceived Value of Mobile Internet influenced Mobile Internet Behavioral Intention significantly and Behavioral Intention had a significant effect on Mobile Intent usage by results. This paper concludes with discussion of these results and their implications for researcher and Mobile Internet company managers.

• Journal of Korean Society of Water and Wastewater
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• v.28 no.5
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• pp.509-516
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• 2014

This study describes a reasonable planning method for water meter replacement which can minimize the metering under-registration for an increasement of revenue water. The increment analysis of real water usage was used to establish a replacement plan. The meter replacement database collected from K City was used as the basis of this analysis. The database included 964 connections of domestic and non-domestic consumers that had their meter replaced by aging at 2011. The result showed that the corelation between unregistered water volume and water meter age was lower than commonly expected where the current criteria of replacement is only water meter age(8 years) excluding the meters older than 13 years. And in the analysis result of water usage for 8 years, the total amount and increment of water usage had a significant effect on unregistered water volume. However the relation was different tendency as a total volume and slope of increment. In case of total water volume was larger than 10,000, larger than 7,000 and increment of 0.0 ~ -0.3, larger than 6,000 and increment more than -0.3 were analysed to need a replacement because of metering under-registration.

• Asia pacific journal of information systems
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• v.16 no.3
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• pp.159-176
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• 2006

Collaborative filtering is one of the popular techniques for personalized recommendation in e-commerce. In collaborative filtering, user profiles are usually managed per product category in order to reduce data sparsity. Product diversification of Internet storefronts and multiple product category sales of e-commerce portals require cross-product category usage of user profiles in order to overcome the cold start problem of collaborative filtering. In this paper, we study the feasibility of cross-product category usage of user profiles, and suggest a method to improve recommendation performance of cross-product category user profiling. First, we investigate whether user profiles on a product category can be used to recommend products in other product categories. Furthermore, a way of utilizing user profiles selectively is suggested to increase recommendation performance of cross-product category user profiling. The feasibility of cross-product category user profiling and the usefulness of the proposed method are tested with real click stream data of an Internet storefront which sells multiple product categories including books, music CDs, and DVDs. The experiment results show that user profiles on a product category can be used to recommend products in other product categories. Also, the selective usage of user profiles based on correlations between subcategories of two product categories provides better performance than the whole usage of user profiles.

• Journal of IKEEE
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• v.23 no.2
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• pp.448-453
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• 2019

Under the conflicting objectives of maximum user satisfaction and fast launching, there exist great needs for automated mobile app testing. In automated app testing, detection of usage-state changes is one of the most important issues for minimizing human intervention and testing of various usage scenarios. Because conventional approaches utilizing pre-collected training examples can not handle the rapid evolution of apps, we propose a novel method detecting changes in usage-state through graph-entropy. In the proposed method, widgets in a screen shot are recognized through DNNs and 'onverted graphs. We compared the performance of the proposed method with a SIFT (Scale-Invariant Feature Transform) based method on 20 real-world apps. In most cases, our method achieved superior results, but we found some situations where further improvements are required.

• Korean journal of communication and information
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• v.46
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• pp.485-510
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• 2009

Since the inception of Internet Protocol TV's real-time service on January, 2009, technological challenges and lack of content diversity of IPTV have been cited as problem areas. While past researches focused on IPTV's technological, industrial and policy facets, this research surveyed the viewers' viewing and usage patterns, and the level of service satisfaction among actual audiences of MegaTV, SKBroadband, and LGTV since January. The results show that subscription fee and content types were the two dominant determinants in audience's choice of a particular IPTV company. The high users of IPTV were on average aged between 30-39, and women tended to be heavier users than men. The surveyed audience also regarded IPTV to be more similar to the Internet than any other medium such as Cable TV and Satellite TV. IPTV audience cited 'lifestyle service' and 'additional service' offerings to be highly relevant to their usage and satisfaction; interactive service and educational service also showed high correlation to usage and satisfaction. The most watched contents on IPTV were domestic TV series, followed by foreign movies and variety shows. 'Fees for additional features,' 'lack of real-time terrestrial TV service', and 'lack of content variety' were the major areas of concern for IPTV viewers. They answered that the monthly fee was the most important factor in the selection of IPTV. Use of pay-per-view contents and add-on interactive service fees were also seen as problematic. With regards to future usage, the IPTV audience revealed that they were very sensitive and reluctant to pay for additional services. While existing researches concentrated on IPTV's technological problems and lack of content diversity, this study illuminated the more pragmatical side of the viewers, namely, the importance of price in audience's selection of an IPTV service provider. From these results, it is recommended that, before doing anything else, the service providers try to meet the audience's expected price points in order to garner the full potential of IPTV and the attendant mass audience.