• KSII Transactions on Internet and Information Systems (TIIS)
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• v.13 no.7
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• pp.3733-3755
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• 2019

E-cash has its merits comparing with other payment modes. However, there are two problems, which are how to achieve practical/complete tracing and how to achieve it in compact E-cash. First, the bank and the TTP (i.e., trusted third party) have different duties and powers in the reality. Therefore, double-spending tracing is bank's task, while unconditional tracing is TTP's task. In addition, it is desirable to provide lost-coin tracing before they are spent by anyone else. Second, compact E-cash is an efficient scheme, but tracing the coins from double-spender without TTP results in poor efficiency. To solve the problems, we present a compact E-cash scheme. For this purpose, we design an embedded structure of knowledge proof based on a new pseudorandom function and improve the computation complexity from O(k) to O(1). Double-spending tracing needs leaking dishonest users' secret knowledge, but preserving the anonymity of honest users needs zero-knowledge property, and our special knowledge proof achieves it with complete proofs. Moreover, the design is also useful for other applications, where both keeping zero-knowledge and leaking information are necessary.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.32 no.2
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• pp.405-416
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• 2022

Current AI technology is improving the quality of life by using machine learning based on data. When using machine learning, transmitting distributed data and collecting it in one place goes through a de-identification process because there is a risk of privacy infringement. De-identification data causes information damage and omission, which degrades the performance of the machine learning process and complicates the preprocessing process. Accordingly, Google announced joint learning in 2016, a method of de-identifying data and learning without the process of collecting data into one server. This paper analyzed the effectiveness by comparing the difference between the learning performance of data that went through the de-identification process of K anonymity and differential privacy reproduction data using actual financial data. As a result of the experiment, the accuracy of original data learning was 79% for k=2, 76% for k=5, 52% for k=7, 50% for 𝜖=1, and 82% for 𝜖=0.1, and 86% for Federated learning.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.23 no.5
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• pp.977-983
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• 2013

This paper presents result of researching personal information exposure of Korean twitter and facebook users. Personally identifiable information such as e-mail and phone numer is exposed in the accounts less than 1%. However there are many cases that a person is identified by non personally identifiable information. For example, 350 thousands accounts are distinguished with other accounts because its name is unique. Using combination of information such as name and high school, we can distinguish 2.97 millions accounts. We also found 170 thousands account pairs that are candidate of one users' own account. Linkability between two accounts in two different domains means that the person is identified. Currently, only personally identifiable information is protected by policy. This paper shows that the policy has limited effects under the circumstances that a person can be identified by non personally identifiable information and the account linking is possible.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.27 no.6
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• pp.1519-1534
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• 2017

Data de-identification is the one of the technique that preserves individual data privacy and provides useful information of data to the analyst. However, original de-identification techniques like k-anonymity have vulnerabilities to background knowledge attacks. On the contrary, differential privacy has a lot of researches and studies within several years because it has both strong privacy preserving and useful utility. In this paper, we analyze various models based on differential privacy and formalize a differentially private model on financial data. As a result, we can formalize a differentially private model on financial data and show that it has both security guarantees and good usefulness.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.10 no.3
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• pp.1273-1288
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• 2016

With the swift growth of wireless technologies, an increasing number of users rely on the mobile services which can exchange information in mobile networks. Security is of key issue when a user tries to access those services in this network environment. Many authentication schemes have been presented with the purpose of authenticating entities and wishing to communicate securely. Recently, Chou et al. and Farash-Attari presented two ID authentication schemes. They both claimed that their scheme could withstand various attacks. However, we find that the two authentication schemes are vulnerable to trace attack while having a problem of clock synchronization. Additionally, we show that Farash-Attari's scheme is still susceptible to key-compromise impersonation attack. Therefore, we present an enhanced scheme to remedy the security weaknesses which are troubled in these schemes. We also demonstrate the completeness of the enhanced scheme through the Burrow-Abadi-Needham (BAN) logic. Security analysis shows that our scheme prevents the drawbacks found in the two authentication schemes while supporting better secure attributes. In addition, our scheme owns low computation overheads compared with other related schemes. As a result, our enhanced scheme seems to be more practical and suitable for resource-constrained mobile devices in mobile networks.

• Korean Journal of Adult Nursing
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• v.21 no.4
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• pp.423-434
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• 2009

Purpose: This study was conducted to evaluate successful aging (SA) in elderly individuals and to determine the factors that influence SA. Methods: The subjects included 207 elderly individuals from D city, Korea. The data were obtained between July 1 and August 30, 2008. The participants were assured of anonymity and confidentiality. For the evaluation, Kim & Shin's SA scale, Lawton's instrumental activities of daily living (IADL) scale, Jon's self-esteem scale, Kee's geriatric depression scale short form-Korean (GDSSF-K), and Hong's productive activities scale were used. The data were analyzed using descriptive statistics, the t-test, analysis of variance (ANOVA), and Pearson correlation coefficients; multiple regression analysis was performed using the SPSS/WIN 10.0 program. Results: The maximum score for SA was 34, and the mean score was 22.62. It was found that SA was significantly correlated to IADL, self-esteem, depression, and productive activity. Depression was the most powerful predictor of SA and it accounted for 40.6% of the total variance in SA. Self-esteem, productive activity, living situation, economic status, and age together accounted for 62.1% of the total variation in SA. Conclusion: Depression, self-esteem, and productive activity were identified as variables that influence SA. On the basis of these results, we conclude that nurses should assist elderly individuals in order to facilitate SA. Moreover, individualized nursing management strategies must be developed in order to facilitate SA.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2008.10a
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• pp.703-707
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• 2008

Nowadays, Internet becomes an essential element in our life. We can make use of numerous on-line services through Internet such as information search, on-line shopping, e-mail service, etc. But, while getting the benefits of Internet service, invasion of our privacy frequently occurs because on-line service providers tend to request excessive or unnecessary personal information. So, there have been some researches on anonymous authentication, which means that user can authenticate herself, not revealing her identity or personal information. But, most of the researches are not somewhat applicable to current authentication infrastructure. In this paper, we propose a pseudonym-based anonymous PKI with short group signature. Using our proposed scheme, we can provide anonymity with conditional traceability to current PKI.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.20 no.2
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• pp.260-267
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• 2016

The Internet has brought lots of changes to us sharing information mutually. However, as all social symptom have double-sided character, it has serious social problem. Vicious users have been taking advantage of anonymity on the Internet, stating comments aggressively for defamation, personal attacks, privacy violation and more. Malicious comments on the Internet are creating the biggest problem regarding unlawful acts and insults which occur on the Internet. In order to solve the issues, several studies have been done to efficiently manage the comments. However, there are limitations to recognize modified malicious vocabulary in previous research. So, in this paper, we propose a malicious comments detection technique by improving limitation of previous studies. The experimental result has shown accuracy of 87.8% providing higher accuracy as compared to previous studies done.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• v.9 no.2
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• pp.545-548
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• 2005

Recently, the computing environment of P2P come out to solve the excessive load of the server in the computing environment of the client/server. Currently, operated computing environment of P2P is mainly spreading out P2P system of read name or anonymity base about a publisher, sender and receiver of the file. But, to the current file protection there is three problem. The first problem is to a host become attack target. The second is to received file loose attack of Brute Force. The third is to define target of attack of DOS. To solve the this problem. it divide file into block unit. Each block is safely scattered peers. This paper propose the distribution P2P system of file division. Both proposing system solve the this problem and promote efficiency of file application.

• Journal of Digital Convergence
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• v.11 no.12
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• pp.537-549
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• 2013

This study examines implications for the Korean military health survey from literature review on foreign military health surveys. The authors discuss backgrounds, objectives, participants, methods, contents, organizations involved, and cycles of foreign military health surveys from literature review from peer-reviewed journals as well as reports and documents collected from web-sites of governmental organizations. Common and distinguishing characteristics were found from foreign military health surveys. First, the military health surveys have evolved in phases in the direction of reducing health risk factors. Second, the importance of mental health is being emphasized. Third, cooperations and collaborations of governments, universities, and professional agencies are important in order to ensure anonymity and expertise on data collection and analysis. Finally, health surveys are conducted on a regular basis through institutionalization. To monitor and to promote health of military personnel, it is critical for Korea to establish the legal and institutional environment and to recognize the importance as well as the need of military health surveys at the national level.