• The KIPS Transactions:PartA
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• v.11A no.3
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• pp.213-216
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• 2004

Proirity queues(PQ) can be used in applications such as scheduling or sorting. The data structures for PQ can be constructed with or without pointers. The implicit representation without pointers uses less memory space than pointer-based representation. It if shown that a 2-heap, a traditional Implicit PQ based on a binary tree, is slower than an f-heap based on a 8-ary tree. This is because 8-heap utilizes cache memory more efficiently This paper presents a novel fast implicit heap called 8-heap＊ which is easier to implement. Experimental results show that the 8-heap＊ is faster than 8-heap as well as 2-heap.

• Journal of KIISE:Computing Practices and Letters
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• v.10 no.1
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• pp.1-13
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• 2004

The Semantic Web introduces the next generation of the Web by establishing a semantic layer of machine-understandable data to enable machines (i.e intelligent agents) retrieve more relevant information and execute automated web services using semantic information. Ontology-related technologies are very important to evolve the World Wide Web of today into the Semantic Web in representation and share of semantic data. In this paper, we proposed and implemented the efficient ontology management system, K-Box, which constructs and manages ontologies using topic maps. We can use K-Box system to construct, store and retrieve ontologies. K-Box system has several components: Topicmap Factory, Topicmap Provider, Topicmap Query Processor, Topicmap Object Wrapper, Topicmap Cache Manager, Topicmap Storage Wrapper.

• The KIPS Transactions:PartD
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• v.8D no.1
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• pp.1-9
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• 2001

The SQL CLl (Call Level Interface) is a database application programming interface (API) that fits the client-server environment, and its de facto standards such as ODBC and JDBC are widely employed in various applications. The current SQL CLl standards, however, do not specify enough features for efficient retrieval of large objects (LOBs) that constitute the multimedia data. In this paper, we propose the LOB caching through the SQL CLl and describe the extension of the SQL eLl to achieve such a goal. We implement our proposal by extending the SQL CLl library for BADA - II DBMS developed at ETRI, and evaluate the performance of LOB retrieval through the cache compared to that of LOB retrieval conducted solely with the functions specified in the current SQL CLl standards.

• International Journal of Internet, Broadcasting and Communication
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• v.10 no.4
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• pp.6-11
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• 2018

As embedded memory technology evolves, the traditional Static Random Access Memory (SRAM) technology has reached the end of development. For deepening the manufacturing process technology, the next generation memory technology is highly required because of the exponentially increasing leakage current of SRAM. Non-volatile memories such as STT-MRAM (Spin Torque Transfer Magnetic Random Access Memory), PCM (Phase Change Memory) are good candidates for replacing SRAM technology in embedded memory systems. They have many advanced characteristics in the perspective of power consumption, leakage power, size (density) and latency. Nonetheless, nonvolatile memories have two major problems that hinder their use it the next-generation memory. First, the lifetime of the nonvolatile memory cell is limited by the number of write operations. Next, the write operation consumes more latency and power than the same size of the read operation.These disadvantages can be solved using the compiler. The disadvantage of non-volatile memory is in write operations. Therefore, when the compiler decides the layout of the data, it is solved by optimizing the write operation to allocate a lot of data to the SRAM. This study provides insights into how these compiler and architectural designs can be developed.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.34 no.6B
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• pp.615-622
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• 2009

In this paper, we consider the problem of applying NEMO in PMIPv6, and propose a method to support network mobility. When an MR enters a PMIPv6 domain, an MAG recognizes the MR to access using the BU message. And the MAG makes a tunnel between the MAG and the MR. The MR do not make tunnel fundamentally except for handover. Therefore, the PMIPv6 protocol needs to modify the original algorithm and the BCE data filed. However, the proposed method can use NEMO without protocol modification. To show verification, we implement our proposed algorithm with added BCE data filed using C program, and configure a testbed network. Through a network connectivity procedure, we can see that our proposed method can support network mobility within the PMIPv6 network.

• Proceedings of the Korea Information Processing Society Conference
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• 2017.11a
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• pp.702-705
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• 2017

최근 들어 개인정보 보호의 중요성에 대한 인식이 높아지고 있다. 개인정보 위협 요소 증가 및 유출 사고 증가 등으로 개인정보 보호 필요성이 높아지고 있으며, 개인정보보호법 발효 및 시행에 따른 기술적 보호 마련을 위하여 외국계 카드 발행사에서 지속적으로 PCI DSS(Payment Card Industry Data Security Standard)의 준수를 요청하고 있다. 카드 소유자의 데이터를 전송, 처리, 저장하는 환경에 대한 인증으로 적격업체 선정의 자격을 주기도 한다. 이러한 보안성 심의 기준이 강화되고 있으나 DB 암호화 제품인 TDE(Transparent Data Encryption) 방식의 암호화 방법은 암호화 기능 이외에 접근제어, 키 기밀성 보장을 위한 옵션의 추가 도입 검토가 필요하며, 서비스를 위해서 DB 전용 메모리 영역(SGA)의 Buffer Cache에 평문(Plain Text)으로 복호화한 후 로드하여 사용하므로 예상치 못한 또 다른 심각한 데이터 유출의 위험이 있다. 본 논문에서는 개인정보 암호화 방법을 연구하고 구현과정에서 발생한 문제에 대한 해결 과정을 설명하였다.

• Journal of Information Processing Systems
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• v.18 no.2
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• pp.245-257
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• 2022

In the Internet of Things (IoT) era, the types of devices used by one user are becoming more diverse and the number of devices is also increasing. However, a forensic investigator is restricted to exploit or collect all the user's devices; there are legal issues (e.g., privacy, jurisdiction) and technical issues (e.g., computing resources, the increase in storage capacity). Therefore, in the digital forensics field, it has been a challenge to acquire information that remains on the devices that could not be collected, by analyzing the seized devices. In this study, we focus on the fact that multiple devices share data through account synchronization of the online platform. We propose a novel way of identifying the user's interest through analyzing the remnants of targeted advertising which is provided based on the visited websites or search terms of logged-in users. We introduce a detailed methodology to pick out the targeted advertising from cache data and infer the user's interest using deep learning. In this process, an improved learning model considering the unique characteristics of advertisement is implemented. The experimental result demonstrates that the proposed method can effectively identify the user interest even though only one device is examined.

• The KIPS Transactions:PartA
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• v.12A no.3 s.93
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• pp.243-252
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• 2005

This paper introduces a noble modeling technique to build data communication prediction models in multiprocessors, using Least-Squares and Robust Estimation methods. A set of sample communication rates are collected by using a few small input data sets into workload programs. By applying estimation methods to these samples, we can build analytic models that precisely estimate communication rates for huge input data sets. The primary advantage is that, since the models depend only on data set size not on the specifications of target systems or workloads, they can be utilized to various systems and applications. In addition, the fact that the algorithmic behavioral characteristics of workloads are reflected into the models entitles them to model diverse other performance metrics. In this paper, we built models for cache miss rates which are the main causes of data communication in shared memory multiprocessor systems. The results present excellent prediction error rates; below $1\%$ for five cases out of 12, and about $3\%$ for the rest cases.

• Journal of the Institute of Electronics and Information Engineers
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• v.49 no.12
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• pp.149-155
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• 2012

SSD is a storage device of having high-performance controller and cache buffer and consists of many NAND flash memories. Because NAND flash memory does not support in-place update, valid pages are invalidated when update and erase operations are issued in file system and then invalid pages are completely deleted via garbage collection. However, garbage collection performs many erase operations of long latency and then it reduces I/O performance and increases wear leveling in SSD. In this paper, we propose a new method of de-duplicating valid data and recycling invalid data. The method de-duplicates valid data and then recycles invalid data so that it improves de-duplication ratio. Due to reducing number of writes and garbage collection, the method could increase I/O performance and decrease wear leveling in SSD. Experimental result shows that it can reduce maximum 20% number of garbage collections and 9% I/O latency than those of general case.

• Journal of KIISE:Computing Practices and Letters
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• v.6 no.4
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• pp.383-392
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• 2000

Currently, multiprocessors are evaluated almost exclusively with scientific applications. Commercial applications are rarely explored because it is difficult to obtain the source codes of commercial DBMS. Even when the source code is available, such as for POSTGRES, understanding the source code enough to perform detailed meaningful performance evaluations is a daunting task for computer architects.To evaluate multiprocessors with commercial applications, we have developed our own DBMS, called EZDB. EZDB is a parallelized DBMS, loosely inspired from POSTGRES, and running on top of a software architecture simulator. It is capable of executing parallel programs written in SQL. Contrary to POSTGRES, EZDB is not intended as a prototype for a production-quality DBMS. Its purpose is to easily run and evaluate the performance of commercial applications on multiprocessor architectures. To illustrate the usefulness of EZDB, we showed the cache performance data collected for the TPC-B benchmark on a shared-memory multiprocessor. The simulation results showed that the data structures exhibited unique sharing characteristics and that their locality properties and working sets were very different from those in scientific applications.