• Journal of the Korea Society of Computer and Information
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• v.18 no.9
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• pp.79-89
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• 2013

Recently, the need for outsourcing sensitive data has grown due to the wide spreading of cost-effective and flexible cloud service. However, there is a fundamental concern in using such service since users have to trust external servers. Therefore, searchable encryption can be a very valuable tool to meet the security requirements of data outsourcing. However, most of work on searchable encryption focus only on privacy preserving search function and relatively lacks research on encryption mechanism used to actually encrypt data. Without a suitable latter mechanism, searchable encryption cannot be deployed in real world cloud services. In this paper, we analyze previously used and possible data encryption mechanisms for multi-user searchable encryption system and discuss their pros and cons. Our results show that readily available tools such as broadcast encryption, attribute-based encryption, and proxy re-encryption do not provide suitable solutions. The main problem with existing tools is that they may require separate fully trusted servers and the difficulty in preventing collusion attacks between outsiders and semi-trusted servers.

• Journal of the Korea Society of Computer and Information
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• v.23 no.9
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• pp.35-42
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• 2018

In this paper, we propose an optimal streaming service method based on Hybrid CDN/P2P architecture. Recently, video streaming utilizes a CDN (Content Delivery Network) operation technique based on a Proxy Server, which is an end node located close to a user. However, since CDN has a fixed network traffic bandwidth and data information exchange among CDNs in the network is not smooth, it is difficult to guarantee traffic congestion and quality of image service. In the hybrid CDN/P2P network, a data selection technique is used to select only the data that is expected to be continuously requested among all the data in order to guarantee the QoS of the user who utilizes the limited bandwidth efficiently. In order to search user requested data, this technique effectively retrieves the storage information of the constituent nodes of CDN and P2P, and stores the new image information and calculates the deletion priority based on the request possibility as needed. Therefore, the streaming service scheme proposed in this paper can effectively improve the quality of the video streaming service on the network.

• The Journal of Asian Finance, Economics and Business
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• v.8 no.3
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• pp.69-77
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• 2021

The objective of this research is to explore the inconclusive theoretical and empirical association between institutional ownership and firm performance in the context of emerging Pakistani economy. The data set consists of all the non-financial firms listed on the Pakistan Stock Exchange (PSX). Annual data set covers the period ranging from 2010 to 2015. However, the econometric analysis does not include those firms with incomplete data. Thus the final data set comprised of an unbalanced panel of sample of 276 firms with 1231 firms years observations. Data related to the institutional ownership and other variables taken for the study were extracted through the annual financial reports of the firms. The research used Tobin's Q as a proxy of market measure of firm performance and tested the endogenous relation with institutional ownership through OLS and 2SLS approach. The study also applied Durbin-Wu-Hausman test to determine the endogeneity before analyzing the 2SLS model. The Durbin-Wu-Hausman Test (DWH) conform the endogenous link between institutional ownership and performance and vice versa. The results derived from 2SLS also confirm a highly significant relationship and two way direct proportional relationships between the institutional investment and corporate performance in the studied companies.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.1
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• pp.231-237
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• 2017

This study examines the relationship between voluntary information disclosure and the effective tax rate using Investor Relation (IR) as the proxy for the level of the firm's voluntary information disclosure, and effective corporate tax rate as the proxy for the level of tax avoidance. This study considers sample data from 1,396 firms listed on the Korea Composite Stock Price Index (KOSPI) from 2011-2014. The results of this study are as follows: Investor Relation (IR) had a positive correlation with effective corporate tax rate. This result got on with the result of additional analysis using extra measurement of effective corporate tax rate. According to these results, we expect that firms featuring greater voluntary information disclosure report enhanced business performance. This study contributes understanding how Investor Relation (IR) affects tax avoidance. We hope that this study can promote the development of capital markets and provide good news to investors for firms that have greater information disclosure.

• Journal of Information Processing Systems
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• v.12 no.2
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• pp.196-213
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• 2016

System Architecture Evolution (SAE) with Long Term Evolution (LTE) has been used as the key technology for the next generation mobile networks. To support mobility in the LTE/SAE-based mobile networks, the Proxy Mobile IPv6 (PMIP), in which the Mobile Access Gateway (MAG) of the PMIP is deployed at the Serving Gateway (S-GW) of LTE/SAE and the Local Mobility Anchor (LMA) of PMIP is employed at the PDN Gateway (P-GW) of LTE/SAE, is being considered. In the meantime, the Host Identity Protocol (HIP) and the Locator Identifier Separation Protocol (LISP) have recently been proposed with the identifier-locator separation principle, and they can be used for mobility management over the global-scale networks. In this paper, we discuss how to provide the inter-domain mobility management over PMIP-based LTE/SAE networks by investigating three possible scenarios: mobile IP with PMIP (denoted by MIP-PMIP-LTE/SAE), HIP with PMIP (denoted by HIP-PMIP-LTE/SAE), and LISP with PMIP (denoted by LISP-PMIP-LTE/SAE). For performance analysis of the candidate inter-domain mobility management schemes, we analyzed the traffic overhead at a central agent and the total transmission delay required for control and data packet delivery. From the numerical results, we can see that HIP-PMIP-LTE/SAE and LISP-PMIP-LTE/SAE are preferred to MIP-PMIP-LTE/SAE in terms of traffic overhead; whereas, LISP-PMIP-LTE/SAE is preferred to HIP-PMIP-LTE/SAE and MIP-PMIP-LTE/SAE in the viewpoint of total transmission delay.

• Proceedings of the Korea Contents Association Conference
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• 2006.11a
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• pp.478-482
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• 2006

This paper implemented speech-library and the Web Services that conversion the Web page for the speech recognition. The system is consisted of Web services consumer and Web services providers. The Web services consumer has libraries that Speech-library and proxy-library. The Speech -library has functions as follows from the user's speech extracted speech-data and searching the URL in link-table that is mapped with user's speech. The proxy-library calls two web services and is received the returning result. The Web services provider consisted of Parsing Web Services and Speech-Recognition Web Services. Parsing Web Services adds ActiveX control and reconstructs web page using the speech recognition. The speech recognizer is the web service providers that implemented in the previous study. As the result of experiment, we show that reconstructs web page and creates link-Table. Also searching the URL in link-table that is mapped with user's speech. Also confirmed returning the web page to user by searching URL in link-table that is mapped with the result of speech recognition web services.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.11
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• pp.637-643
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• 2017

This study analyzed the Quality of Accounting Earning of Investor Relations(IR). For this, we utilized Book-Tax Difference Variability as the proxy of the level of the Quality of Accounting Earning. This study used 2,106 sample data from 2011 to 2016 on the listed firm on KOSPI(Korea Composite Stock Price Index). In short, the study results are as follows. Investor Relation(IR) has a negative relevance with Book-Tax Difference Variability, which agreed with the result of additional analysis using extra sample. According to these results, we can expect that Investor Relations(IR) firms will report more faithful Accounting Earning. This study makes the following fresh contribution to the field. The study result confirms how Investor Relation(IR) affects the Quality of Accounting Earning. We hope that this study will help the development of capital market.

• Journal of Digital Contents Society
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• v.14 no.3
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• pp.283-290
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• 2013

The current centralized mobility control protocols such as proxy mobile IPv6 (PMIPv6) are dependent on a central mobility anchor to process all control/data traffic. However, such centralized mobility control protocols have some drawbacks such as traffic concentration into the core network and serious service degradation in case of the failure of such a centralized mobility anchor, etc. In this paper, therefore, in order to alleviate these drawbacks, we propose a PMIPv6-based distributed mobility control scheme considering a user's movement locality. Performance evaluation results demonstrate that the proposed scheme has apparent potentials to alleviate serious drawbacks of S-PMIP, which is a closely-related distributed mobility control scheme, as well as PMIPv6, while reducing the total mobility control cost.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.31 no.4A
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• pp.377-384
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• 2006

According to fast VoIP technology development, more and more companies change voice network into IP based network among branch offices. IP PBX, which is deployed up to now, composed of IP phone and VoIP Gateway. Every telphone has replaced with If phone which support VoIP and VoIP gateway is installed in PBTN connection point to relay voice data. It can reduce the communication expense of International call, long distance call and call between a headquater and a trance because it uses internet line. In this paper, IP PBX is implemented that can distribute call using PBX network only usig personal terminal without Proxy Server. Depending on Role, terminal can be registered Master, Server and Client and it is verified in terms of performance and validation.

• Asia-Pacific Journal of Business
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• v.11 no.4
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• pp.205-224
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• 2020

Purpose - This study aimed to identify the effects of ownership structures on agency costs in internationally diversified firms listed on the KOSDAQ market. Design/methodology/approach - A total of 5,824 samples were finally selected and empirically analyzed for a total of nine years from 2011 to 2019, during which the International Accounting Standards had been mandatory for firms listed on the KOSDAQ market. Findings - The results of this study showed that the effects of ownership structures on the ratio of asset turnover are positive for the major share and foreign equity ratios of international diversified firms. Moreover, by selecting the ratio of entertainment expenses as a proxy for agency expenses, this study confirmed that the effects of the ownership structure of an international diversified entity on entertainment expenditure were determined to show a significantly negative relation to entertainment expenditure, thus indicating that the higher the ratio of major shareholders, the more appropriately control the expenditure of entertainment expenses through arbitrary private deviations of the management.Furthermore, considering the effect of the ownership structure on the expenditure of sales and administrative expenses as a proxy variable for agency costs, this study verified that the majority share ratio of international diversified firms was negative to the expenditure of sales and administrative expenses, confirming that the higher the share of major shareholders, the lower the selling and administrative costs, but insignificant.Finally, as a result of determining whether the ownership structure of an international diversified firm affects the holding of free cash, the majority share of this firm shows a significantly negative relation to the ratio of the holding of surplus cash, indicating that the higher the proportion of major shareholders, the more appropriately control the holding of the entity's free cash through arbitrary private deviance by the manager. Research implications or Originality - Major shareholders of an internationally diversified firm listed on the KOSDAQ market play a positive role in the firm's performance by properly controlling agency costs that may be incurred by the management.