• Journal of the Korea Society for Simulation
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• v.3 no.1
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• pp.125-134
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• 1994

In real-time database systems, transactions's commitment done before the given deadlines is more important than just getting the maximum throughput. Transactions missing the given deadlines are no longer meaningful in real-time applications. Therefore, there is a need for new transaction processing models to meet the given deadlines in real-time database applications, because moat conventional transaction models are not designed to meet deadlines. In this paper we propose a new transaction models which uses multiple versions of a data item. The model uses read-from graphs and dynamic reorder of transactions to meet deadlines. A read-from graph contains the past read semantics of read operations and support the model to decide which database operation to be taken. Then, we show simulation results comparing the proposed model with other transaction models such as two phase locking model and the optimistic concurrency control model.

• Journal of Information Processing Systems
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• v.11 no.3
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• pp.389-405
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• 2015

Most traditional database systems exploit a record-oriented model where the attributes of a record are placed contiguously in a hard disk to achieve high performance writes. However, for read-mostly data warehouse systems, the column-oriented database has become a proper model because of its superior read performance. Today, flash memory is largely recognized as the preferred storage media for high-speed database systems. In this paper, we introduce a column-oriented database model based on flash memory and then propose a new column-aware flash indexing scheme for the high-speed column-oriented data warehouse systems. Our index management scheme, which uses an enhanced $B^+$-Tree, achieves superior search performance by indexing an embedded segment and packing an unused space in internal and leaf nodes. Based on the performance results of two test databases, we concluded that the column-aware flash index management outperforms the traditional scheme in the respect of the mixed operation throughput and its response time.

• Proceedings of the Korea Information Processing Society Conference
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• 2018.05a
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• pp.44-47
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• 2018

시계열 데이터 처리를 위해 방대한 양의 데이터를 스토리지에서 빠르게 읽어와 처리하려는 움직임이 많아지고 있다. 이를 위해 스토리지의 read latency 를 개선하기 위한 여러 기법들이 제안되었지만, 이 기법들은 분산 노드의 스토리지 자원을 충분히 활용하지 못한다는 한계가 있다. 따라서 우리는 시계열 데이터를 실시간으로 처리하기 위해 스토리지에 병렬적으로 접근하여 read latency 를 개선하는 기법을 제안한다. 제안된 기법은 분산 환경에서 스토리지에 병렬적으로 접근하여, 각 노드에서 부분적으로 데이터를 읽어와 전체 데이터를 읽어오는 지연시간을 줄인다. 우리는 제안된 기법을 여러 노드로 구성된 분산 환경에서 구현하였다. 제안된 기법을 적용한 결과, 전체 데이터를 읽어오는 read latency 가 기존 기법보다 28.04% 줄어든 것을 확인하였다.

• ETRI Journal
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• v.38 no.3
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• pp.518-528
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• 2016

The searching of an extensive document database for documents that are locally similar to a given query document, and the subsequent detection of similar regions between such documents, is considered as an essential task in the fields of information retrieval and data management. In this paper, we present a framework for such a task. The proposed framework employs the method of short-read mapping, which is used in bioinformatics to reveal similarities between genomic sequences. In this paper, documents are considered biological objects; consequently, edit operations between locally similar documents are viewed as an evolutionary process. Accordingly, we are able to apply the method of evolution tracing in the detection of similar regions between documents. In addition, we propose heuristic methods to address issues associated with the different stages of the proposed framework, for example, a frequency-based fragment ordering method and a locality-aware interval aggregation method. Extensive experiments covering various scenarios related to the search of an extensive document database for documents that are locally similar to a given query document are considered, and the results indicate that the proposed framework outperforms existing methods.

• Phonetics and Speech Sciences
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• v.9 no.2
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• pp.9-22
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• 2017

The purpose of this paper is to report the whole process of developing Korean Standard Speech Database (KSS DB). This project is supported by SPO (Supreme Prosecutors' Office) research grant for three years from 2014 to 2016. KSS DB is designed to provide speech data for acoustic-phonetic and phonological studies and speaker recognition system. For the samples to represent the spoken Korean, sociolinguistic factors, such as region (9 regional dialects), age (5 age groups over 20) and gender (male and female) were considered. The goal of the project is to collect over 3,000 male and female speakers of nine regional dialects and five age groups employing direct and indirect methods. Speech samples of 3,191 speakers (2,829 speakers and 362 speakers using direct and indirect methods, respectively) are collected and databased. KSS DB designs to collect read and spontaneous speech samples from each speaker carrying out 5 speech tasks: three (pseudo-)spontaneous speech tasks (producing prolonged simple vowels, 28 blanked sentences and spontaneous talk) and two read speech tasks (reading 55 phonetically and phonologically rich sentences and reading three short passages). KSS DB includes a 16-bit, 44.1kHz speech waveform file and a orthographic file for each speech task.

• Journal of KIISE:Computing Practices and Letters
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• v.14 no.8
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• pp.758-762
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• 2008

Embedded systems usually utilize Flash Memories with very nice characteristics of non-volatility, low access time, low power and so on. For the multimedia database systems, R-tree is an indexing tree with nice characteristics for multimedia access. MR-tree, which is an upgraded version of R-tree, has shown better performance in searching, inserting and deleting operations than R-tree. Flash memory has sectors and blocks as a unit of read, write and delete operations. Especially, the delete is done on a unit of 512 byte blocks with very large operation time and it is also known that read and write operations on a unit of block matches caching nature of MT-tree. Our research optimizes MR-tree operations in a unit of Flash memory blocks. Such an adjusting leads in better indexing performance in database accesses. With MR-tree on a 512B block units we achieved fast search time of database indexing with low height of MR-tree as well as faster update time of database indexing with the best fit of flash memory blocks. Thus MR-tree with optimized operations shows good characteristics to be a database index schemes on any systems with flash memory.

• Digital Contents
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• no.8 s.159
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• pp.66-71
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• 2006

예전에 모뎀을 통한 PC통신이 한창 유행할 때, ROM족이라는 유행어가 있었다. RAM(Random Access Memory)과 함께 컴퓨터의 기억장치로 활용되는, 읽기만 가능한 저장매체(Read Only Memory)를 뜻하는 용어였다. 그런데 이 용어는 이 속성을 빗대어 게시판을 읽기만 하는 회원(Read Only Member)을 가리키는 말로도 쓰였다. 정보화시대에 있어서 정보라는 것, 비록 형태가 없는 것들이 대부분이지만 이 역시 누군가가 사용하기 위해서는 누군가가 만들어내야 한다. 수요와 공급이 일어나는 정보 유통 구조다. 혹자는 ROM족으로 소비생활에만 치중하지만, 또 다른 혹자들은 소비와 생산을 동시에 하는 프로슈머(ProSumer) 역할을 한다. 이번호에서는 이러한 생산성을 띤 소비자들에 대한 이야기를 하고자 한다.

• Proceedings of the IEEK Conference
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• 2000.07b
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• pp.735-738
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• 2000

The most important issue in database security is correct concurrency control under the restrictive security policy. The goal of secure transaction management is to keep security and provide many concurrent users with the high availability of database. In this paper, we consider the security environment of multidatabase system with replicated data. The read-from relationship in the existed serializability is improper in security environment. So, we define new read-from relationship and propose new secure 1-copy quasi-seriailzability by utilizing this relationship and display some examples. This security environment requires both the existed local autonomy and the security autonomy as newly defined restriction. To solve covert channel problem is the most difficult issue in developing secure scheduling scheme. The proposed secure 1-copy quasi-serializability is very proper for global transactions in that this serializability not violates security autonomy and prevents covert channel between global transactions.

• Proceedings of the Korea Database Society Conference
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• 1996.04a
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• pp.3-29
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• 1996

Multimedia Management -Naive View -images, audio, and video -store these as BLOBs, along with a tag, in an RDB for read retrieval(omitted)

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.7
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• pp.293-300
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• 2016

Traditional databases exploit a record-based model, where the attributes of a record are placed contiguously in a slow hard disk to achieve high performance. On the other hand, for read-intensive data analysis systems, the column-based compressed database has become a proper model because of its superior read performance. Currently, flash memory SSD is largely recognized as the preferred storage media for high-speed analysis systems. This paper introduces a compressed column-storage model and proposes a new index and its data management scheme for a high-capacity data warehouse system. The proposed index management scheme is based on the asymmetric index duplication and achieves superior search performance using the master index and compact index, particularly for large read-mostly databases. In addition, the data management scheme contributes to the read performance and high reliability by compressing the related columns and replicating them in two mirrored SSD. Based on the results of the performance evaluation under the high workload conditions, the data management scheme outperforms the traditional scheme in terms of the search throughput and response time.