• IEMEK Journal of Embedded Systems and Applications
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• v.11 no.6
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• pp.335-341
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• 2016

As information technology advances rapidly, various smart devices are becoming an essential element in our lives. Smart devices are providing services to users through applications up on the operating system. Operating systems have a variety of rules, such as scheduling applications and controlling hardwares. Among those rules, it is significant to protect private information in the information-oriented society. Therefore, isolation task, that makes certain memory space separated for each application, should highly be guaranteed. However, modern operating system offers the function to access the memory space from other applications for the sake of debugging. If this ability is misused, private information can be leaked or modified. Even though the access authority to memory is strictly managed, there exist cases found exploited. In this paper, we analyze the problems of the function provided in the Android environment that is the most popular and opened operating system. Also, we discuss how to avoid such kind of problems and verify with experiments.

• IMMUNE NETWORK
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• v.23 no.1
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• pp.11.1-11.11
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• 2023

Memory T cells that mediate fast and effective protection against reinfections are usually generated upon recognition on foreign Ags. However, a "memory-like" T-cell population, termed virtual memory T (T_VM) cells that acquire a memory phenotype in the absence of foreign Ag, has been reported. Although, like innate cells, T_VM cells reportedly play a role in first-line defense to bacterial or viral infections, their protective or pathological roles in immune-related diseases are largely unknown. In this review, we discuss the current understanding of T_VM cells, focusing on their distinct characteristics, immunological properties, and roles in various immune-related diseases, such as infections and cancers.

• IEMEK Journal of Embedded Systems and Applications
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• v.17 no.1
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• pp.59-65
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• 2022

Virtual memory is used as the method to ensure the safety of the system through memory protection in the real-time system. TLB miss caused by using virtual memory makes the real-time system WCET more pessimistically. TLB lockdown can be applied as a method to improve this problem. However, processors with limited TLB lockdown entries, a selection criterion is needed to efficiently utilize the TLB lockdown entry. In this paper, the most frequently accessed virtual pages in the process are applied to the TLB lockdown by analyzing memory profiling. The results showed that micro data TLB miss stall cycle and main data TLB miss stall cycle of the processor decreased by at least 4.7% and up to 29.7%.

• Journal of Internet Computing and Services
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• v.17 no.6
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• pp.93-101
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• 2016

As the Android smart phones become more popular, applications that handle users' personal data such as IDs or passwords and those that handle data directly related to companies' income such as in-game items are also increasing. Despite the need for such information to be protected, it can be modified by malicious users or leaked by attackers on the Android. The reason that this happens is because debugging functions of the Linux, base of the Android, are abused. If an application uses debugging functions, it can access the virtual memory of other applications. To prevent such abuse, access controls should be reinforced. However, these functions have been incorporated into Android O.S from its Linux base in unmodified form. In this paper, based on an analysis of both existing memory access functions and the Android environment, we proposes a function that verifies thread group ID and then protects against illegal use to reinforce access control. We conducted experiments to verify that the proposed method effectively reinforces access control. To do that, we made a simple application and modified data of the experimental application by using well-established memory editing applications. Under the existing Android environment, the memory editor applications could modify our application's data, but, after incorporating our changes on the same Android Operating System, it could not.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.11 no.4
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• pp.2276-2291
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• 2017

Data protection of removable storage devices is an important issue in information security. Unfortunately, most existing data protection mechanisms are aimed at protecting computer platform which is not suitable for ultra-low-power devices. To protect the flash disk appropriately and efficiently, we propose a trust based USB flash disk, named UTrustDisk. The data protection technologies in UTrustDisk include data authentication protocol, data confidentiality protection and data leakage prevention. Usually, the data integrity protection scheme is the bottleneck in the whole system and we accelerate it by WH universal hash function and speculative caching. The speculative caching will cache the potential hot chunks for reducing the memory bandwidth pollution. We adopt the symmetric encryption algorithm to protect data confidentiality. Before mounting the UTrustDisk, we will run a trusted virtual domain based lightweight virtual machine for preventing information leakage. Besides, we prove formally that UTrustDisk can prevent sensitive data from leaking out. Experimental results show that our scheme's average writing throughput is 44.8% higher than that of NH scheme, and 316% higher than that of SHA-1 scheme. And the success rate of speculative caching mechanism is up to 94.5% since the access pattern is usually sequential.