• Journal of Communications and Networks
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• v.12 no.1
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• pp.52-66
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• 2010

Since large objects consume substantial resources, web proxy caching incurs a fundamental trade-off between performance (i.e., hit-ratio and latency) and overhead (i.e., resource usage), in terms of caching and relaying large objects to users. This paper investigates how and to what extent the current dedicated-server based web proxy caching scheme is affected by large file transfers in a high bandwidth campus network environment. We use a series of trace-based performance analyses and profiling of various resource components in our experimental squid proxy cache server. Large file transfers often overwhelm our cache server. This causes a bottleneck in a web network, by saturating the network bandwidth of the cache server. Due to the requests for large objects, response times required for delivery of concurrently requested small objects increase, by a factor as high as a few million, in the worst cases. We argue that this cache bandwidth bottleneck problem is due to the fundamental limitations of the current centralized web proxy caching model that scales poorly when there are a limited amount of dedicated resources. This is a serious threat to the viability of the current web proxy caching model, particularly in a high bandwidth access network, since it leads to sporadic disconnections of the downstream access network from the global web network. We propose a peer-to-peer cooperative web caching scheme to address the cache bandwidth bottleneck problem. We show that it performs the task of caching and delivery of large objects in an efficient and cost-effective manner, without generating significant overheads for participating peers.

• The Journal of Information Technology
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• v.7 no.3
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• pp.63-81
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• 2004

The third party logistics(3PL) is generally understood as the logistics activities providing a comprehensive logistics services, all or partly outsourced by the customers on a larger term contract basis, ranging from making logistics strategies to implementing information technology services. A lot of companies in advanced countries such as the U.S.A. or some of the European countries have actively outsourced to logistics service providers in efforts to increase the efficiencies in logistics operation rather than doing themselves. In light of these environments, outsourcing to third parties has become a strategic issue demanding greater attention in corporate boardrooms. First, after deciding their logistics outsourcing, the companies have to set up their aims of 3PL through the development of logistical strategies. Second, the companies must decide service provider that fits to their business environment and conditions. As it is reported that 3PL services will bring a high rate of return and its potential will be more signigicant, providers and users of 3PL services and government ministry should prepare the way of improvement of logistics institution and plan to activate 3PL services to reach the advanced foreign countries level.

• Journal of Korea Multimedia Society
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• v.10 no.9
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• pp.1106-1116
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• 2007

Recently e-commerce trade on the web has grown rapidly in scale and complexity, just as web site designs and web servers have become more complicated. In view of these complexities, it is obviously difficult to analyse web user's data since they web users employ so many different web paths. The existing association rule investigation algorithms identify all items with a high correlation. However even though users often only want to find items in which they have interest, it is still difficult to find the rules they want out of all of the many association rules found by existing algorithms. In this paper, we propose a system linking each node with the sequence association rule, linking all routes after finding a path corresponding to a user with the association rule-one of the data mining techniques which identify user patterns in web user paths. The suggested system helps us construct individualized or customer-subdivided sites using the sequence association rule in order to harmonize the paths of web users with user characters.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.12 no.1
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• pp.189-195
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• 2008

The OFDMA Physical layer in the WiMAX standard of IEEE 802.16e adopts 114 LDPC codes with various code rates and block sizes as a channel coding scheme to meet varying channel environments and different requirements for transmission performance. In this paper, the performances of the LDPC codes are evaluated according to various code rates and block-lengths throueh simulation studies using min-sum decoding algorithm in AWGN chamois. As the block-length increases and the code rate decreases, the BER performance improves. In the cases with code rates of 2/3 and 3/4, where two different codes ate specified for each code rate, the codes with code rates of 2/3A and 3/4B outperform those of 2/3B and 3/4A, respectively. Through the statistical analyses of the number of decoding iterations the decoding complexity and the word error rates of LDPC codes are estimated. The results can be used to trade-off between the performance and the complexity in designs of LDPC decoders.

• Korean Journal of Labor Studies
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• v.24 no.1
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• pp.261-295
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• 2018

This study draws on data from the 1st (2005) to 6th (2015) waves of the Workplace Panel Survey regarding workplaces with labor representatives, i.e., a trade union or labor-management council, and analyzes these using a fixed effects panel data model to examine the relationship between the level of worker participation and the economic performance of workplaces. Analysis results indicate that higher levels of worker participation in an earlier time period are associated with higher per-worker value added (productivity) and per-worker labor costs (wages) at the current time period, but only up to a certain level beyond which the effect is found to decrease, thus forming an inverted-U shape pattern. Considered from a broad framework, these results are in line with the theoretical predictions by Freeman and Lazear (1995), who had established the logic behind the dynamics of the participation of labor representatives in management activities. In view of the fact that the current average level of worker participation in Korea is very low, the empirical analysis results of this study presents the policy implication that raising the level of workplace participation somewhat beyond current levels would yield improvements in economic performance in terms of the shared rent between labor and management - i.e., productivity (per-worker value added).

• Journal of the Korea Institute of Information Security & Cryptology
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• v.12 no.2
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• pp.35-44
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• 2002

In this paper, an implementation method of RSA exponentiator based on Radix-$2^k$ modular multiplication algorithm is presented and verified. We use Booth receding algorithm to implement Radix-$2^k$ modular multiplication and implement radix-16 modular multiplier using 2K-byte memory and CSA(carry-save adder) array - with two full adder and three half adder delays. For high speed final addition we use a reduced carry generation and propagation scheme called pseudo carry look-ahead adder. Furthermore, the optimum value of the radix is presented through the trade-off between the operating frequency and the throughput for given Silicon technology. We have verified 1,024-bit RSA processor using Altera FPGA EP2K1500E device and Samsung 0.3$\mu\textrm{m}$ technology. In case of the radix-16 modular multiplication algorithm, (n+4+1)/4 clock cycles are needed and the 1,024-bit modular exponentiation is performed in 5.38ms at 50MHz.

• New & Renewable Energy
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• v.17 no.1
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• pp.50-60
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• 2021

This study investigated the reference case in the UK where legality and sustainability were systematically established for forest biomass represented by wood pellets. The UK is the country that best utilizes the trade value of wood pellets based on sustainability, with bioenergy accounting for 31% of total renewable energy production. The UK imported wood pellet, estimated 8,697 thousand tons in 2019. The UK government has continuously improved the renewable generation policy system to ensure the sustainability of wood pellets. The weighted average greenhouse gas emissions of a UK biomass power plant that received a Renewable Obligation Certificate (ROC) in 2018-19 was 26.71 gCO2e/MJ. These power plants are expected to meet the upper limit of 72.2 gCO2e/MJ by 2025. To issue an ROC, the biomass power plant must demonstrate that 70% of its total biofuel usage is sustainable. The UK uses the Sustainable Biomass Program (SBP) certification system, which is gradually expanding to other European countries, to prove the sustainability of biomass energy fuels. Global wood pellet production with SBP certification in 2019 was 10.5 Mt. This trend has significant implications for introducing additional sustainability into the wood pellet policy of South Korea.

• Transactions of the Korean hydrogen and new energy society
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• v.34 no.2
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• pp.91-99
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• 2023

Participation in power trading using surplus power is considered a business model active in the domestic energy trade market, but it is limited only if the legal requirements according to the type, capacity, and use of the facilities to be applied for are satisfied. The hydrogen residential demonstration model presented in this paper includes solar power, energy storage system (ESS), fuel cell, and water electrolysis facilities in electrical facilities for private use with low-voltage power receiving system. The concept of operations strategy for this model focuses on securing the energy self-sufficiency ratio of the entire system, securing economic feasibility through the optimal operation module installed in the energy management system (EMS), and securing the stability of the internal power balancing issue during the stand-alone mode. An electric facility configuration method of a hydrogen residential complex demonstrated to achieve this operational goal has a structure in which individual energy sources are electrically connected to the main bus, and ESS is also directly connected to the main bus instead of a renewable connection type to perform charging/discharging operation for energy balancing management in the complex. If surplus power exists after scheduling, participation in power trading through reverse transmission parallel operation can be considered to solve the energy balancing problem and ensure profitability. Consequentially, this paper reviews the legal regulations on participation in electric power trading using surplus power from hydrogen residential models that can produce and consume power, gas, and thermal energy including hybrid distributed power sources, and suggests action plans.

• Food Science of Animal Resources
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• v.42 no.2
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• pp.313-320
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• 2022

Brazil is considered as a great broiler feet exporter, especially for the Chinese trade. Contact lesions at the tibiotarsal region are responsible for economic losses and there is no model for its classification, thereby this study presents a fast and practical grade system to be used in the poultry industry and proposes these lesion characterizations into three different grades. For this, correlation was made between macroscopic, histological findings and microbiological quantification (Escherichia coli, Staphylococcus spp., Streptococcus spp. and sulphite-reducing clostridia) from contact lesions in the tibiotarsal region of 112 broiler carcasses, divided in four groups (n=28), accordingly to the lesion's intensity. There were no significant differences in microbiological quantification among the groups (p>0.05) except for the grade 3 group, as grade 1 and 2 lesions were in the early stages and histopathological changes such as ulceration were not observed. In grade 3 lesion group, it was observed bacterial cocci grume and ulceration at the articular region and significantly higher microbiological count (p<0.05) for E. coli and Staphylococcus spp. In conclusion, the visual standard proposed in this work, correlated and confirmed by the histopathologic, and microbiologic characterization, allows to precise and fast ascertainment of the contact lesion grade in the tibiotarsal regions of broiler carcasses. Moreover, it should be highlighted that grades 1 and 2 alterations are not caused by an inflammatory process caused by pathogenic agents and should not be considered a public health risk.

• Journal of the Korean Institute of Gas
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• v.28 no.2
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• pp.56-65
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• 2024

This study was conducted for the purpose of analyzing the impact of ESG activities of gas-related energy companies (organizations) striving for carbon neutrality on job performance through employees' organizational pride and organizational trust. The survey results of 345 gas-related public organizations and private companies were analyzed using Smart PLS 4.0, and the research model and hypothesis were established and verified. As a result of the verification, ESG activities related to environmental (E) activities did not affect organizational pride and organizational trust, but social (S) activities and governance (G) activities were found to have a significant impact on organizational pride and organizational trust. In addition, organizational pride and organizational trust were found to have an effect on job performance. In particular, it was confirmed that the higher the organizational pride of ESG organization members, the higher the impact of organizational trust on job performance. The study seek to suggest a development direction relation to ESG activities of gas-related energy companies (organizations).