• Journal of KIISE:Information Networking
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• v.36 no.6
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• pp.471-480
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• 2009

One of the principal impediments to the achievement of a scalable access control for a large number of subscribers in a public broadcast is to distribute key update messages reliably to all stateless receivers. However, in a public broadcast, the rekeying messages can be dropped or compromised during the transmission over an insecure broadcast channel, or transmitted to the receivers while it was off-line. In this study, we propose a novel group key management scheme that features a mechanism that allows the legitimate receivers to recover the current group key even if they lose key update messages for long-term sessions using short hint messages and member computation. The performance analysis result shows that the proposed scheme has advantages of the scalable and efficient rekeying compared with the previous reliable group key distribution schemes. The proposed key management scheme targets a conditional access system in a media broadcast where there is no feedback channel from receivers to the broadcasting station.

• The Journal of the Korea Contents Association
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• v.4 no.3
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• pp.53-60
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• 2004

In this paper we present user authentication and key distribution using threshold PKC(Public Key Cryptosystem), which is secure against the dictionary attack. The n servers hold a t-out-of-n sharing of the dealer's secret key. When the server authenticate a user, at least f of them cooperate they can reconstruct password verifier.

• Electronics and Telecommunications Trends
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• v.33 no.6
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• pp.94-106
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• 2018

A quantum key distribution (QKD) provides in principle an unconditional secure communication unlike the standard public key cryptography depending on the computational complexity. In particular, free-space QKD can give a secure solution even without a fiber-based infrastructure. In this paper, we investigate an overview of recent research trends in the free-space QKD system, including satellite and handheld moving platforms. In addition, we show the key components for a free-space QKD system such as the integrated components, single photon detectors, and quantum random number generator. We discuss the technical challenges and progress toward a future free- space QKD system and components.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.12 no.6
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• pp.71-80
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• 2002

To provide the confidentiality of messages transmitted over the network, the use of cryptographic system is increasing gradually and the hybrid cryptosystem, which combines the advantages of the symmetric cryptosystem and the public key cryptosystem is widely used. In this paper, we proposes a new hybrid cryptosystem capable of providing implicit authentication for the sender of the ciphertext by means of the 1-pass key distribution protocol that offers implicit key authentication, hash function and symmetric cryptosystem. Also, we describe some examples such as the Diffie-Hellman based system and the Nyberg-Ruppel based system. The proposed hybrid cryptosystem is an efficient more than general public key cryptosystems in the aspect of computation work and provides implicit authentication for the sender without additional increase of the communication overhead.

• Journal of the Korean Society for Library and Information Science
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• v.56 no.4
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• pp.377-397
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• 2022

The number of public libraries in Korea has been increasing. However, the focus was on quantitative growth, while it did not have much interests in whether its growth trend are have deviations by region, and if that is a fact, what factors caused such a disparity. For this reason, this study analyzes spatial distribution of public libraries in Korea and its affecting factors of regional gap. As a result, public libraries are constantly distributing in the metropolitan area and the distribution of public libraries showed deviations by region. The results of analysis regarding the determinants of public libraries distribution, rate of population growth, the number of businesses and financial independence rate are found to have a positive effect but local taxes per capita are not. Especially economic power of region and financial ability of a local government are key factors of regional disparity. It shows empirically that the supply of public libraries has been determined by the convenience of suppliers.

• Journal of information and communication convergence engineering
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• v.15 no.3
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• pp.160-164
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• 2017

Public key cryptography (PKC) is the basic building block for the cryptography applications such as encryption, key distribution, and digital signature scheme. Among many PKC, elliptic curve cryptography (ECC) is the most widely used in IT systems. Recently, very efficient Montgomery-Twisted-Edward (MoTE)-ECC was suggested, which supports low complexity for the finite field arithmetic, group operation, and scalar multiplication. However, we cannot directly adopt the MoTE-ECC to new PKC systems since the cryptography is not fully evaluated in terms of performance on the Internet of Things (IoT) platforms, which only supports very limited computation power, energy, and storage. In this paper, we fully evaluate the MoTE-ECC implementations on the representative IoT devices (16-bit MSP processors). The implementation is highly optimized for the target platform and compared in three different factors (ROM, RAM, and execution time). The work provides good reference results for a gradual transition from legacy ECC to MoTE-ECC on emerging IoT platforms.

• The Journal of Industrial Distribution & Business
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• v.13 no.3
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• pp.13-24
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• 2022

Purpose: The purpose of this paper is to investigate key factors that affect customer dissatisfaction on public transportation system by highlighting the necessity of citizen participation and improved management of advanced technology for sustainability. Research questions applied in this study include following; i) how are factors on dissatisfaction related to types of transportation modes; ii) how do perceived proposed factors affect citizen dissatisfaction; iii) how do the improvement of public transportation service affect the level of expected satisfaction; and iv) how do expected satisfaction affect policy agreement and government trust. Research design, data and methodology: For qualitative research, civil opinions were collected and chi-square analysis was applied using keywords. For quantitative research, online survey was collected and factor and multiple regression analyses were applied. 3) Results: This study found that efficiency of operation system and safety on dissatisfaction showed significant in all three public transportation modes. This study found that perception of government policy and trust on government will increase as expected satisfaction increases. Conclusions: This study provides managerial and policy implications on society and policy makers by addressing necessity of improving strategies for public transportation system with the consideration of citizen relationship management and sustainable development.

• Journal of Environmental Impact Assessment
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• v.22 no.3
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• pp.255-264
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• 2013

This paper diagnosed the assessment problems and development types of the simple statement of the Sea Area Utilization Consultation System. and suggested the key assessment items for system improvement. The major types of Public Water occupation and use, and distribution characteristic of regional and coastal were analyzed by evaluate 529 review items during 2010-2012. The artificial structure installation including harbor and fishing port facilities in the South and West coast, and seawater supply and drainage for land-based aquaculture and power plant were dominated. The checklists considering each types of occupation and use in Public Water were suggested. In addition, policy proposals for system improvement were suggested.

• Journal of Internet Computing and Services
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• v.11 no.4
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• pp.143-158
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• 2010

The illegal leakage of enterprise digital confidential information will threaten the enterprise with bankruptcy. Today since most small-and-medium companies have no capability to fight against illegally compromising their critically confidential documents in spite of knowing the leakage of them, strongly safe distribution system of the digital confidential documents should be designed so in secure as to prevent any malicious intent of embezzlement from accessing the critical information. Current DRM-based protection system is not always perfect to protect the digital secrets, even seems to leave the secrets open. Therefore our study has analyzed the illegal leakage paths that hackers attack against and the vulnerability of the current protection systems. As result, we study the group communication based system architecture satisfying the security conditions to make even legitimate working employee keep out of the confidential documents, without performance degradation. The main idea of this architecture is to stay every secrets in encrypted form; to isolate the encrypted documents from the crypto-key; to associate every entity with one activity and to authenticate every entity with DSA-based public key system; multiple authentication method make hackers too busy to get a privilege to access the secrets with too many puzzle pieces. This paper deal with the basic architectural structure for the above issues.

• Asian Pacific Journal of Cancer Prevention
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• v.15 no.13
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• pp.5299-5303
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• 2014

Background: To explore etiology for providing scientific clues for the prevention of lung cancer. Materials and Methods: Data for lung cancer incidence and meteorological geographic factors from 25 counties in Zhejiang province of China during 2011 were studied. Stepwise multiple regression and correlation analysis were performed to analyze the geographic distribution and epidemiology of lung cancer. Results: 8,291 new cases (5,998 in males and 2,293 females) of lung cancer during 2011 in Zhejiang province were reported in the 25 studied counties. Reported and standardized incidence rates for lung cancer were 58.0 and 47.0 per 100,000 population, respectively. The incidence of lung cancer increased with age. Geographic distribution analysis shows that the standardized incidence rates of lung cancer in northeastern Zhejiang province were higher than in the southwestern part, such as in Nanhu, Fuyang, Wuxing and Yuyao counties, where the rates were more than 50 per 100,000 population. In the southwestern Zhejiang province, for instance, in Yueqing, Xianju and Jiande counties, the standardized incidence rates of lung cancer were lower than 37 per 100,000 population. Spearman correlation tests showed that forest coverage rate, air quality index (AQI), and annual precipitation level are associated with the incidence of lung cancer. Conclusions: Lung cancer in Zhejiang province shows obvious regional differences. High incidence appears associated with low forest coverage rate, poor air quality and low annual precipitation. Therefore, increasing the forest coverage rate and controlling air pollution may play an important role in lung cancer prevention.