• Korean Chemical Engineering Research
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• v.48 no.6
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• pp.763-767
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• 2010

High-pressure phase behavior for the binary mixture of 1-propanol with supercritical $CO_2$ has been measured by means of a high-pressure phase equilibrium apparatus equipped with a variable-volume view cell. The equilibrium loci of the pressure - composition and pressure - temperature were obtained for the binary mixture of 1-propanol + $CO_2$ system at 305.15 K, 313.15 K, 323.15 K and 333.15 K, and from 2 MPa to 11 MPa. The critical temperature of the mixture increased with the temperature. The pressure-composition line for the binary mixture of $CO_2$-1-propanol system showed a typical type-II phase behavior. The experimental P-x envelopes were correlated by using the Peng-Robinson equation of state in a satisfactory manner to obtain the parameters with $k_{ij}=0.116$ and ${\eta}_{ij}=-0.065$.

• Journal of the Korean Association of Geographic Information Studies
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• v.18 no.3
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• pp.52-62
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• 2015

As a recent dominant web trend, mobile first strategy has been emphasized, and interests with respect to responsive web that provides effective methodology to various mobile devices and their display resolution are also increasing. However, it is an early adoption stage in web mapping for geo-spatial applications. This study is to present some practical examples of layouts using responsive web technologies linked to geo-spatial open platform. Suggestive consideration points for further application of responsive web to geo-spatial services are presented. On test implementing, HTML5, JavaScript, and CSS3 were used, and web mapping processing using OpenLayers was performed. It is expected that responsive web applications for contents derived from geo-spatial information or location data increase.

• The KIPS Transactions:PartD
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• v.9D no.1
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• pp.111-126
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• 2002

As the technical aspect of the web system development is, unlike the existing main frame or client/server environment, greatly influenced by the dynamic and variable factors and carried out in a comparatively short period, practical and efficient process to which the developer may adapt with ease is very much required for the web system development. However, while the technological substitute, language and architecture composition have been much discussed, in connection with web system development growing rapidly, standardized development process and its deliverables have been rarely discussed. This thesis analyzes problems of the existing web system development processes and as the substitutes for them, proposes web system development process based on the domain features derived from the concepts of iteration and increment. For the classification of domains, five domains in total are set by interlocking web system factors and web site types and the workflows for two domains applied to projects are incorporated focused on work content and deliverables. The proposed process applies to the development of intranet system and is compared with the existing web development processes by the measure classified into components and elements.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.34 no.8B
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• pp.797-804
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• 2009

Recently, SIP(Session Initiation Protocol) is used to set up and manage sessions for multimedia applications such as VoIP(Voice over IP) and IMS(IP Multimedia Subsystem). However, because SIP operates over the Internet, it is exposed to pre-existed internet security threats such as service degradation or service disruptions. Multimedia applications which are delay sensitive even suffers more from the threats mentioned above. The proposed methods so far to detect SIP INVITE flooding are CUSUM(Cumulative Sum), Hellinger distance and adaptive threshold, but among methods only take normal state into consideration. So, it is not capable of adapting the condition of the network congestion which are dynamically changing. In this paper, SIP INVITE flooding detection algorithm considering network congestion which enables efficient detections of such attacks is proposed. The proposed algorithm is expected to detect other types of attacks such as BYE and CANCEL more precisely compared to other methods.

• The KIPS Transactions:PartA
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• v.16A no.4
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• pp.289-298
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• 2009

Generally, RFID systems are composed of one reader and several passive tags, and share the single wireless channel. For this reason, collisions occurwhen more than two tags simultaneously respond to the reader's inquiry. To achieve this problem, many papers, such as QT[8], HCT[10], BSCTTA[2], and QT-BCS[9], have been proposed. In this paper, we propose the tree-based anti-collision algorithm using a bit change sensing unit (TABCS) based on BSCTTA algorithm. The proposed algorithm can identify bits returned from tags through bit change sensing unit, even if multi collisions occur. So, it rapidly generates the unique prefix to indentify each tag, and reduce the total of bits. As the result, the cost of identifying all tag IDs is relatively reduced as compared with existing algorithms. It is verified through simulations that the proposed algorithm surpass other existing algorithms.

• Journal of Industrial Convergence
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• v.18 no.5
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• pp.23-29
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• 2020

The Internet of things (IoT) is the extension of Internet connectivity into various devices and everyday objects. Embedded with electronics, Internet connectivity and other forms of hardware. The IoT poses significant risk to the entire digital ecosystem. This is because so many of these devices are designed without a built-in security system to keep them from being hijacked by hackers. This paper proposed a mutual authentication protocol for IoT Devices using symmetric-key algorithm. The proposed protocol use symmetric key cryptographic algorithm to securely encrypt data on radio channel. In addition, the secret key used for encryption is random number of devices that improves security by using variable secret keys. The proposed protocol blocked attacker and enabled legal deives to communicate because only authenticated devices transmit data by a mutual authentication protocol. Finally, our scheme is safe for attacks such as eavesdropping attack, location tracking, replay attack, spoofing attack and denial of service attack and we confirmed the safety by attack scenario.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.24 no.2
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• pp.149-157
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• 2020

Today, due to the large amount of data duplication caused by the increase in user data, various deduplication studies have been conducted. However, research on personal storage is relatively poor. Personal storage, unlike high-performance computers, needs to perform deduplication while reducing CPU and memory resource usage. In this paper, we propose an adaptive algorithm that selectively applies fixed size chunking (FSC) and whole file chunking (WFH) according to the file type and size in order to maintain the deduplication rate and reduce the load in personal storage. We propose an algorithm for minimization. The experimental results show that the proposed file system has more than 1.3 times slower at first write operation but less than 3 times reducing in memory usage compare to LessFS and it is 2.5 times faster at rewrite operation.

• Journal of Practical Engineering Education
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• v.15 no.2
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• pp.519-528
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• 2023

Recently, for the preservation and transmission of cultural heritage, various researches and content development based on technologies such as virtual reality, augmented reality, and extended reality, which are the core technologies of the 4th industrial revolution era, are being conducted. Intangible cultural heritage is variable, unlike tangible cultural heritage, so it changes greatly depending on time and space, and as a result, it is in danger of being discontinued due to the aging and death of the inheritors. In this study, the current status and cases of related realistic content production were collected and analyzed, focusing on statistical data, intangible cultural heritage training centers through search portals, and platform cases. As a result of the analysis, it was found that overall, there were very few cases of use in content and transfer education using intangible cultural heritage. Through this study, we will consider ways to revitalize the effective transfer education of intangible cultural heritage that is on the verge of being cut off from transmission.

• Asia-Pacific Journal of Business Venturing and Entrepreneurship
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• v.15 no.4
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• pp.245-261
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• 2020

The aim of this study is to investigate the correlation between the support activities provided by the franchiser and how they affect the intention of the contract renewal and business performances made by franchisees, developing dynamic trust between these transactional partners. Various supportive activities between franchiser and franchisees were divided into financial and non-financial activities and dynamic trust into Transitional-based trust, Calculative-based trust, Relational-based trust, and Balanced-based trust. These trust types, which are variable and adjustable based on the opportunistic behaviors of business parties, were applied to define the impact of the support activities on the contract renewal intention and the performances. This study was developed around domestic franchisees. An investigator visited business owners and manager level-employees, explained the purpose of the survey prior to the response, and the answers were directly written by hands. A total of 348 copies were used for the analysis. As the results of the analysis, first, financial support activities were found to have a positive(+) effect on transitional-based trust, calculative-based trust, and balanced-based trust. On the other hand, non-financial support activities were found to have a positive(+) effect on calculative-based trust, relational-based trust, and balanced-based trust, and there was no significant relationship on transitional-based trust. Second, the dynamic trust had a statistically significant positive(+) effect on inducing the contract renewal. Lastly, in the relationship between the dynamic trust and its impact on business performances, only transitional-based trust, and relational-based trust were found to have a positive(+) effect on the financial performances. In addition, relational-based trust showed a meaningful positive(+) relationship on the non-financial performances, and non-financial performace showed a meaningful positive(+) relationship on the re-contract intention. From the results, it can be concluded that the financial and non-financial activities for a win-win partnership between franchiser and franchisees are essential in not only forming dynamic trust but also boosting business performances as well as maintaining the business relationship. Thus, it suggests that building a win-win partnership can be promoted more efficiently by specifying activities best suitable for a particular relationship. In addition, a specific set of activities could be presented for establishing the level of trust that is formed in situations that vary depending on transaction risks and interdependency arising from having the transactional relationship based on the contract as the franchise industry features. Eventually, it is expected that this study can provide a way to promote the qualitative improvement of the franchise industry by identifying factors essential to establishing a sustainable win-win system and relationships that can improve the business performance of franchisees.

• Journal of Korean Society of Transportation
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• v.21 no.4
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• pp.113-132
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• 2003

Using nonradial data envelopment analysis(DEA) under assumptions of strong disposability and variable returns scale, this paper annually estimates productive. technical and allocative efficiencies of three publicly-owned rail transit properties which are different in terms of organizational type: Seoul Subway Corporation(SSC, local public corporation), the Seoul Metropolitan Electrified Railways sector (SMESRS) of Korea National Railroad(the national railway operator controlled by the Ministry of Construction and Transportation(MOCT)), and Busan Urban Transit Authority (BUTA, the national authority controlled by MOCT). Using the estimation results of Tobit regression analysis. the paper next computes their true productive, true technical and true allocative efficiencies, which reflect only the impacts of internal factors such as production activity by removing the impacts of external factors such as an organizational type and a track utilization rate. And the paper also computes an organizational efficiency and annually gross efficiencies for each property. The paper then conceptualized that the property produces a single output(car-kilometers) using four inputs(labor, electricity, car & maintenance and track) and uses unbalanced panel data consisted of annual observations on SSC, SMESRS and BUTA. The results obtained from DEA show that, on an average, SSC is the most efficient property on the productive and allocative sides, while SMESRS is the most technically-efficient one. On the other hand. BUTA is the most efficient one on the truly-productive and allocative sides, while SMESRS on the truly-technical side. Another important result is that the differences in true efficiency estimates among the three properties are considerably smaller than those in efficiency estimates. Besides. the most cost-efficient organizational type appears to be a local public corporation represented by SSC, which is also the most grossly-efficient property. These results suggest that a measure to sort out the impacts of external factors on the efficiency of rail transit properties is required to assess fairly it, and that a measure to restructure (establish) an existing(a new) rail transit property into a local public corporation(or authority) is required to improve its cost efficiency.