• KSII Transactions on Internet and Information Systems (TIIS)
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• v.16 no.5
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• pp.1634-1652
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• 2022

Due to the increasing need for data sharing in the age of big data, how to achieve data access control and implement user permission revocation in the blockchain environment becomes an urgent problem. To solve the above problems, we propose a novel blockchain-based data sharing scheme (BDSS) with fine-grained access control and permission revocation in this paper, which regards the medical environment as the application scenario. In this scheme, we separate the public part and private part of the electronic medical record (EMR). Then, we use symmetric searchable encryption (SSE) technology to encrypt these two parts separately, and use attribute-based encryption (ABE) technology to encrypt symmetric keys which used in SSE technology separately. This guarantees better fine-grained access control and makes patients to share data at ease. In addition, we design a mechanism for EMR permission grant and revocation so that hospital can verify attribute set to determine whether to grant and revoke access permission through blockchain, so it is no longer necessary for ciphertext re-encryption and key update. Finally, security analysis, security proof and performance evaluation demonstrate that the proposed scheme is safe and effective in practical applications.

• KIEAE Journal
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• v.7 no.5
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• pp.47-52
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• 2007

The high-rise apartment buildings have been constructed in large quantities to provide housing and used to be the popular residential types in Korea. However, it results that a number of problems are provoked such as the deteriorate of comfort and lack of sunshine access. Based on the judicial precedents, the sunshine access right should be guaranteed to enjoy uninterrupted sunlight for more than two hours continually between 9 am. and 3 pm or for more than four hours between 8 am and 4 pm in the winter solstice. The computer simulations are very strong tools to judge that the sunshine access right is infringed or not. This study aims to evaluate the efficiency of two computer simulation programs such as 3Dmax and Lightscape programs broadly used in field areas. For the study, the three dimensional computer models are suggested, and the simulations are performed on the 30 minutes intervals. Also, the simulation results are compared by the results of scaled model experiments.

• ETRI Journal
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• v.32 no.1
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• pp.112-119
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• 2010

We present a useful design for a free access mat which supports two frequency bands of 2.4 GHz and 5 GHz. The free access mat is a sheet-shaped waveguide which consists of a tightly coupled double-layered microstrip resonator array. It provides easy access for devices in short-range wireless communications. Interference is a common problem with conventional applications which use free space transmission. Our proposed wireless access system uses a subsidiary waveguide, the free access mat. Wireless devices are proximately coupled to the free access mat through which the coupled electromagnetic (EM) wave transmits. The arrival domain of the EM wave of an application is therefore limited to an area close to the free access mat. Wireless devices can be coupled to the free access mat at an arbitrary position without contact. We previously presented a free access mat for a single frequency band. This paper presents a free access mat for the two frequency bands of 2.4 GHz and 5 GHz. The free access mat uses a ring patch resonator array which is easily excited by typical antennas and is resistant to interference. These characteristics are demonstrated by numerical simulation and confirmed by experiment.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.16 no.2
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• pp.565-586
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• 2022

Cloud storage's elastic expansibility not only provides flexible services for data owners to store their data remotely, but also reduces storage operation and management costs of their data sharing. The data outsourced remotely in the storage space of cloud service provider also brings data security concerns about data integrity. Data integrity verification has become an important technology for detecting the integrity of remote shared data. However, users without data access rights to verify the data integrity will cause unnecessary overhead to data owner and cloud service provider. Especially malicious users who constantly launch data integrity verification will greatly waste service resources. Since data owner is a consumer purchasing cloud services, he needs to bear both the cost of data storage and that of data verification. This paper proposes a verification control algorithm in data integrity verification for remotely outsourced data. It designs an attribute-based encryption verification control algorithm for multiple verifiers. Moreover, data owner and cloud service provider construct a common access structure together and generate a verification sentinel to verify the authority of verifiers according to the access structure. Finally, since cloud service provider cannot know the access structure and the sentry generation operation, it can only authenticate verifiers with satisfying access policy to verify the data integrity for the corresponding outsourced data. Theoretical analysis and experimental results show that the proposed algorithm achieves fine-grained access control to multiple verifiers for the data integrity verification.

• Proceedings of the IEEK Conference
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• 2000.07a
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• pp.549-552
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• 2000

We address an access control in the mobile agent-based workflow system. The Role Based Access Control (RBAC) is suitable to model the access control for business processes. However, current RBAC models are not adequate to mobile agent-based workflow system. Because separation of duties becomes complicated and it is impossible to perform several workflows at the same time. To solve these problems, we limit the scope of privilege within the specified task. We define considerations, specification of constraints needed in RBAC when tasks are involved. Also, we present an access control scenario and algorithms in the mobile agent-based workflow system.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.13 no.3
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• pp.1523-1545
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• 2019

Cloud computing is now a widespread and economical option when data owners need to outsource or share their data. Designing secure and efficient data access control mechanism is one of the most challenging issues in cloud storage service. Anonymous broadcast encryption is a promising solution for its advantages in the respects of computation cost and communication overload. We bring forward an efficient anonymous identity-based broadcast encryption construction combined its application to the data access control mechanism in cloud storage service. The lengths for public parameters, user private key and ciphertext in the proposed scheme are all constant. Compared with the existing schemes, in terms of encrypting and decrypting computation cost, the construction of our scheme is more efficient. Furthermore, the proposed scheme is proved to achieve adaptive security against chosen-ciphertext attack adversaries in the standard model. Therefore, the proposed scheme is feasible for the system of data access control in cloud storage service.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.12 no.12
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• pp.6057-6078
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• 2018

Smart home systems provide a safe, comfortable, and convenient living environment for users, whereby users enjoy featured home services supported by the data collected and generated by smart devices in smart home systems. However, existing smart devices lack sufficient protection in terms of data security and privacy, and challenging security and privacy issues inevitably emerge when using these data. This article aims to address these challenging issues by proposing a private blockchain-based access control (PBAC) scheme. PBAC involves employing a private blockchain to provide an unforgeable and auditable foundation for smart home systems, that can thwart illegal data access, and ensure the accuracy, integrity, and timeliness of access records. A detailed security analysis shows that PBAC could preserve data security against various attacks. In addition, we conduct a comprehensive performance evaluation to demonstrate that PBAC is feasible and efficient.

• International Journal of Computer Science & Network Security
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• v.21 no.5
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• pp.168-174
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• 2021

The Cognitive radio (CR) is evolving technology for managing the spectrum bandwidth in wireless network. The security plays a vital role in wireless network where the secondary users are trying to access the primary user's bandwidth. During the allocation the any malicious user either he pretends to be primary user or secondary user to access the vital information's such as credentials, hacking the key, network jam, user overlapping etc. This research paper discusses on various types of attack and to prevent the attack in cognitive radio network. In this research, secondary users are identified by the primary user to access the primary network by the secondary users. The secondary users are given authorization to access the primary network. If any secondary user fails to provide the authorization, then that user will be treated as the malicious user. In this paper two approaches are suggested one by applying elliptic curve cryptography and the other method by using priority-based service access.

• Proceedings of the Korea Information Processing Society Conference
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• 2007.05a
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• pp.1107-1109
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• 2007

Context-based access control is an emerging approach for modeling adaptive solution, making access control management more flexible and powerful. However, these strategies are inadequate for the increased flexibility and performance that ubiquitous computing environment requires because such systems can not utilize effectively all benefit from this environment. In this paper, we propose a solution based on risk to make use of many context parameters in order to provide good decisions for a safety environment. We design a new model for risk assessment in ubiquitous computing environment and use risk as a key component in decision-making process in our access control model.

• Research in Community and Public Health Nursing
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• v.12 no.1
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• pp.150-167
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• 2001

This cross sectional study was done to find out the situation of computer online pornography access by 4th to 6th grade elementary school students. The subjects of this study were three elementary schools in Andong, which were selected randomly and 120 students randomly selected from 4th to 6th grade for a total of 360 students. The questionnaire was composed with the help of a community health nursing professor and through the reference review. The collected data were analysed by a PC SPSS 10.0 according to school grade and sex, an 12-test was implemented to learn what percent of students have computers and software which prohibit the viewing of online pornography, access motivation and time, content viewed, attitude after accessing the contents, and opinions about computer online pornography. The results of this study were as follows. 1. A total of 86.1% of students had computers at home. Most students placed computers in their own room, 78.9% of students had computer online communication experience. Higher grade students tended to have more experience of communications on the internet (P<0.001). Most students chatted on the internet once or twice a week and higher grade students tended to communicate online more frequently. (P<0.001). Most students used computers more than one hour a day (P<0.05). They used computers according to the following priorities: game, studying, listening to music, communications, chatting. 2. Regarding the frequency of going computer online more than seven times per week, male students showed a higher frequency than female students (P<0.05). Male students used computers more than one hour a day and female students less than half an hour (P<0.001). Male students mostly used computers to play computer games. On the other hand. female students used the computer to study, listen to music, and chat (P<0.001). 3. Regarding software installation to prevent access of computer online pornography, a total of 19.4% of students responded they installed one. but 80.6% didn't have any, 20.3% of students had accessed pornography, 46.6% of students responded. they first get to know to the computer online pornography through friends. 4. The reasons for accessing computer online pornography were ranked as follows: curiosity, interest, to release stress, and sex drive (P<0.05). Obscene contents were found in computer games, pictures, and video. Among these, pictures were the most common. 5. Regarding students' attitude toward online pornography, most students responded that they took much pleasure in the contents (P<0.05). 6. Regarding the question 'Does online pornography degrade morals and cause a sex crime', most students responded as 'no'. They also responded positively to the suggestion that the contents would be effective in preventing sex crimes and to release stress. 74.7% of students responded that males' access of the contents as proper but females' access as immoral. Regarding social efforts to protect students from this harmful environment. most replied that those efforts were unnecessary (P<0.001).