• Smart Media Journal
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• v.12 no.2
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• pp.76-82
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• 2023

In the 4th industrial revolution, the blockchain that distributes and manages data through a P2P network is used as a new decentralized networking paradigm in various fields such as manufacturing, culture, and public service. However, with the advent of quantum computers, quantum algorithms that are able to break existing cryptosystems such as hash function, symmetric key, and public key cryptography have been introduced. Currently, because most major blockchain systems use an elliptic curve cryptography to generate signatures for transactions, they are insecure against the quantum adversary. For this reason, the research on the quantum-resistant blockchain that utilizes lattice-based cryptography for transaction signatures is needed. Therefore, in this paper, we propose a blind signature scheme for the blockchain in which the contents of the signature can be verified later, as well as signing by hiding the contents to be signed using lattice-based cryptography with the property of quantum resistance. In addition, we prove the security of the proposed scheme using a random oracle model.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.23 no.1
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• pp.103-110
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• 2019

Electronic voting has been followed by a lot of research as it provides convenience to voters and increases participation rates. Nevertheless, electronic voting has not been widespread yet. The existing electronic voting system does not guarantee credibility, and there arises a question on the security that the voting could be forged or altered by the attack to the central server. In this paper, we proposed blockchain based systems to solve the problems in electronic voting. Although the blockchain may guarantee the security of transaction data, there have been only a few electronic voting systems implemented using the blockchain. We developed blockchain enabled voting and brought out some of its related legal, technical and operational challenges to enforce more security in voting. Unlike centralized voting, the systems could enforce security and solve the problems such as forgery or alteration of transaction data caused by hacking or any attempts to gain control of the central server system.

• KIPS Transactions on Software and Data Engineering
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• v.11 no.7
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• pp.283-290
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• 2022

Blockchain is a technology that secures integrity and transparency by distributing and storing transaction details within multiple node networks. Recently, research is being conducted to secure integrity by applying blockchain to Bill of Lading (B/L documents) of monetary value. In this paper, we study a blockchain-based bill of lading system to improve usability. The shippers register the issued bill of lading on the blockchain, and banks in each country read it to conduct L/C transactions. The consignees receive the goods after completing certification with a quick response code (QR) containing the bill of lading information. Through this, shippers enjoy merits in that they can shorten the time and cost of sending shipping documents by mail and prove the integrity of the documents. The consignees have the advantage of being able to check the documents at the same time as they are registered and trust the transaction. Finally, on the bank side, the security of shipping documents is ensured and verification can be done quickly.

• Land and Housing Review
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• v.12 no.2
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• pp.33-45
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• 2021

Due to recent changes in government policy, officetels have received attention as alternative assets, along with the uplift of office and apartment prices in Seoul. However, the current officetel price indexes use small-size samples and, thus, there is a critique on their accuracy. They rely on valuation prices which lag the market trend and do not properly reflect the volatile nature of the property market, resulting in 'smoothing'. Therefore, the purpose of this paper is to create the officetel price index using transaction data. The data, provided by the Ministry of Land, Infrastructure and Transport from 2005 to 2020, includes sales prices and rental prices - Jeonsei and monthly rent (and their combinations). This study employed a repeat sales model for sales, jeonsei, and monthly rent indexes. It also contributes to improving conversion rates (between deposit and monthly rent) as a supplementary indicator. The main findings are as follows. First, the officetel price index and jeonsei index reached 132.5P and 163.9P, respectively, in Q4 2020 (1Q 2011=100.0P). However, the rent index was approximately below 100.0. Sales prices and jeonsei continued to rise due to high demand while monthly rent was largely unchanged due to vacancy risk. Second, the increase in the officetel sales price was lower than other housing types such as apartments and villas. Third, the employed approach has seen a potential to produce more reliable officetel price indexes reflecting high volatility compared to those indexes produced by other institutions, contributing to resolving 'smoothing'. As seen in the application in Seoul, this approach can enhance accuracy and, therefore, better assist market players to understand the market trend, which is much valuable under great uncertainties such as COVID-19 environments.

• KNOM Review
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• v.23 no.1
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• pp.26-33
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• 2020

Bitcoin is an electronic money that does not rely on centralized institutions such as banks and financial institutions, unlike the world's paper currencies such as dollar, won, euro and yen. In Bitcoin network, a block with transaction details is generated by mining, and the message that the block has been created is broadcast to all participating nodes in a broadcasting method to secure reliability through verification. Likewise, the mining and block propagation methods in the Bitcoin network are greatly affected by the performance of the P2P network. For example, in the case of mining, the node receiving the reward for mining varies depending on whether the block is first mined in the network and the proof of mining is propagated faster. In this paper, we applied local characteristics and Round-to-Trip(RTT) measurement to solve the problems of the existing neighbor connection method and block propagation method performed in Bitcoin network. An algorithm to improve block propagation speed is presented. Through experiments, we compare the performance of the improved algorithm with the existing algorithm to verify that the overall block propagation time is reduced.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 2003.05a
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• pp.44-52
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• 2003

인터넷 뱅킹은 다른 정보시스템이나 웹기반 시스템에 비해 보안에 대한 우려가 높으면서, 다른 거래자들과의 사용자간 거래가 지원되는 P2P적 요소를 가지고 있다. 따라서 보안우려와 거래파트너는 인터넷 뱅킹 사용에 많은 영향을 주는 중요한 요소로 간주될 수 있다. 본 연구에서는 기존의 기술수용모형에 보안우려와 거래파트너 영향을 외부변수로 도입한 확장된 기술수용모형을 제안하였다. 이를 위해 기존에 사용하고 있던 유용성 대신에 편리성을 도입하였고 보안우려와 사용용이성 및 사용은 부( )의 관계, 거래파트너 영향과 편리성 및 사용은 정(+)의 관계에 의해 기존의 기술수용모형에 확장하였다. 실증적 검증을 위해 설문조사를 하였고 조사결과는 구조방정식에 의해 분석하여 만족할만한 모형적합도를 얻었고, '보안우려-사용용이성' 관계를 제외한 모든 가설이 채택되었다.

• Journal of the Korean Society of Clothing and Textiles
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• v.29 no.11
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• pp.1432-1443
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• 2005

The purpose of this study was to identify the relationship among the sub-dimensions of interaction and the relationship between interactions and needs satisfactions in the apparel brand online communities. Subjects of 317 members for 9 selected apparel communities responded the questionnaire in the home-page or in the attached file. The results were as follows: The suggested structural equation model which showed the relationship between the interactions and needs satisfaction in communities were accepted($\chi^2=63.80/df.=48/p=0.06$, GFI=0.97, AGFI=0.95, RMR=0.045, NFI=0.93, AIC=123.80). The interaction of company-consumer hads a positive influence on the interaction of consumers-consumers(H1) and the interaction of consumers-consumers had a positive influence on the interaction of consumers-company(H2). The interaction among community members had a positive influence on the satisfaction of interest needs(H3), transaction needs(H4) and relationship needs(H5) in the community. The relationship needs satisfaction had a positive influence on the interaction of members to the company(H6). Therefore, marketers in apparel company should be fully aware of reciprocal influence among types of interaction when planning marketing programs to promote each type of interaction. Furthermore, they also have to plan marketing activities to manage effective interaction.

• Journal of Intelligence and Information Systems
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• v.19 no.2
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• pp.39-54
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• 2013

Recent explosive increase of electronic commerce provides many advantageous purchase opportunities to customers. In this situation, customers who do not have enough knowledge about their purchases, may accept product recommendations. Product recommender systems automatically reflect user's preference and provide recommendation list to the users. Thus, product recommender system in online shopping store has been known as one of the most popular tools for one-to-one marketing. However, recommender systems which do not properly reflect user's preference cause user's disappointment and waste of time. In this study, we propose a novel recommender system which uses data mining and multi-model ensemble techniques to enhance the recommendation performance through reflecting the precise user's preference. The research data is collected from the real-world online shopping store, which deals products from famous art galleries and museums in Korea. The data initially contain 5759 transaction data, but finally remain 3167 transaction data after deletion of null data. In this study, we transform the categorical variables into dummy variables and exclude outlier data. The proposed model consists of two steps. The first step predicts customers who have high likelihood to purchase products in the online shopping store. In this step, we first use logistic regression, decision trees, and artificial neural networks to predict customers who have high likelihood to purchase products in each product group. We perform above data mining techniques using SAS E-Miner software. In this study, we partition datasets into two sets as modeling and validation sets for the logistic regression and decision trees. We also partition datasets into three sets as training, test, and validation sets for the artificial neural network model. The validation dataset is equal for the all experiments. Then we composite the results of each predictor using the multi-model ensemble techniques such as bagging and bumping. Bagging is the abbreviation of "Bootstrap Aggregation" and it composite outputs from several machine learning techniques for raising the performance and stability of prediction or classification. This technique is special form of the averaging method. Bumping is the abbreviation of "Bootstrap Umbrella of Model Parameter," and it only considers the model which has the lowest error value. The results show that bumping outperforms bagging and the other predictors except for "Poster" product group. For the "Poster" product group, artificial neural network model performs better than the other models. In the second step, we use the market basket analysis to extract association rules for co-purchased products. We can extract thirty one association rules according to values of Lift, Support, and Confidence measure. We set the minimum transaction frequency to support associations as 5%, maximum number of items in an association as 4, and minimum confidence for rule generation as 10%. This study also excludes the extracted association rules below 1 of lift value. We finally get fifteen association rules by excluding duplicate rules. Among the fifteen association rules, eleven rules contain association between products in "Office Supplies" product group, one rules include the association between "Office Supplies" and "Fashion" product groups, and other three rules contain association between "Office Supplies" and "Home Decoration" product groups. Finally, the proposed product recommender systems provides list of recommendations to the proper customers. We test the usability of the proposed system by using prototype and real-world transaction and profile data. For this end, we construct the prototype system by using the ASP, Java Script and Microsoft Access. In addition, we survey about user satisfaction for the recommended product list from the proposed system and the randomly selected product lists. The participants for the survey are 173 persons who use MSN Messenger, Daum Caf$\acute{e}$, and P2P services. We evaluate the user satisfaction using five-scale Likert measure. This study also performs "Paired Sample T-test" for the results of the survey. The results show that the proposed model outperforms the random selection model with 1% statistical significance level. It means that the users satisfied the recommended product list significantly. The results also show that the proposed system may be useful in real-world online shopping store.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.29 no.2
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• pp.377-391
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• 2019

Recently, system studies using tokens and block chains for authentication, access control, etc in IoT environment have been going on at home and abroad. However, existing token-based systems are not suitable for IoT environments in terms of security, reliability, and scalability because they have centralized characteristics. In addition, the system using the block chain has to overload the IoT device because it has to repeatedly perform the calculation of the hash et to hold the block chain and store all the blocks. In this paper, we intend to manage the access rights through tokens for proper access control in the IoT. In addition, we apply the Tangle to configure the P2P distributed ledger network environment to solve the problem of the centralized structure and to manage the token. The authentication process and the access right grant process are performed to issue a token and share a transaction for issuing the token so that all the nodes can verify the validity of the token. And we intent to reduce the access control process by reducing the repeated authentication process and the access authorization process by reusing the already issued token.

• Journal of Korean Academy of Nursing
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• v.4 no.2
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• pp.78-92
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• 1974

It is the purpose of this study to make clear the way in which people can lead a more desirable human life, that is, to ascertain the method of achieving therapeutic change through transaction between nurses and psychiatric patients. The various problems proposed by th9 above-stated aims of study can be shown, such as: What kind of influences does the method of a nurse′s communication have upon the response of psychiatric patients? 1) What are the general methods of communication used by the nurses? 2) Are there any differences between the control group and experimental group in the patients′ "Child" response? 3) Are there any differences between the control group and experimental group in the Patients "Adult" response? 4) What is the most desirable method of communication for therapeutic change in the patients? In an effort to solve the above questions this study attempted and managed to draw a random sampling of 200 patients being accommodated in the National Mental Hospital by dividing them into two groups, experimental groups and control groups, and recording the transactions between nurses and patients. In the course of carrying,: out this study, the experimental group was interviewed by the nurses specially trained In the P.A.C theory. and the control group interviewed at random by the nurses with no special training in communication. Further, the communication between nurses and patients in a free, relaxed atmosphere was allowed only for 15 minutes, whereupon the nurses were requested to make process-recording according to her memory of nurse patient transaction. The process-recording which recorded a series ol transactions between the nurses and the patients was analyzed according to Berne and Harris′transactional Analysis Standard. Through this standard, the writer of this study examined the significance of difference to compare the transactions brought forth between the experimental group and the control group. The following is a summary of the study which the writer of this thesis undertook. Hypothesis to The method of communication which the nurses usually apply to the patients will be higher in "Parent" than in "Adult". The communication which the nurses carried out in the control group turned out to be not significant between "Adult" and "Parent" Accordingly hypothesis 1. carne to be rejected. Hypothesis 2. The patients "Adult" response will be higher in the experimental group than in the control group. According to the result of a CR examination, as the communication showed a significant difference on P〈.01 level′ hypothesis 2 became affirmative. Hypothesis 3. The patients′"Child" response will be higher in the control group than in the experimental group. Hypothesis 3 proved affirmative since it showed an significant degree on P〈.01 level according to the result of a CR examination. Hypothesis 4 "Adult" response of the patient will be higher in frequency by nurses′"Adult" stimulus than nurse′s "Parent" stimulus Chi-square examination revealed significant difference on P〈.05 level. Hypo. 4 is affirmed. The following conclusions are drawn out based on the result of this study. 1) The generally used method of communication stimulus used by nurses for patients proved to be "Adult" and "Parent" in similar proportion. 2) The group in which the nurses could increase the patients "Adult" response proved to be higher in the experimental group than in the control group. Therefore, the communication (or stimulus) which has been applied in the experimental group can be said to be possible method of achieving therapeutic change. 3) Since the patients′"Child" response were higher in the control group than in the experimental group the communication method used In the control group was suggested as the less agreeable method of achieving therapeutic change than that used in the experimental Group. 4) "Adult" response of patient was elicited in significantly greater percentage when the "Adult" stimulus was used by the nurse. Therefore the most desirable method of-communication to give therapeutic change definitely was shown to be the "Adult" stimulus. Recommendations for further studies are as follows: 1) Studies on nurses′role perception in nurse-patient relationships. 2) Studies on patients′response to the method of communication used by nurses according to variables such as sex, social status, educational background, state of health. 3) Application of T.A, method to various groups of patients. 4) Study of various methods to improve student skill in use of process recording.