• Journal of Internet Computing and Services
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• v.2 no.5
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• pp.81-91
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• 2001

XML is a standard markup language for exchange and storage of formed or well-formed information in World Wide Web, Because the source data of XML message for exchange of information in World Woo Web Is stored in legacy database systems. it is necessary the easier connection between XML application and database systems, In Oracle8i. 9i. informix and SQL2000. DBMS vendors extend their DBMSs for XML. This approach for the connection between XML application and database system is Platform-dependent and DBMS-dependent. Therefore it is necessary the platform- and DBMS-independent approach for the connection between XML application and database system, In this paper. we modeled a set of middleware components for relational database design based on XML DTD is modeled, Those components are modeled on object-based algorithm for connection between XML application and database system.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.6 no.5
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• pp.653-660
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• 2002

This paper proposes a method for storing graphs and defining graph algorithms based on the well-developed relational database. In this method, graphs are represented in the form of relations. Each vertex and edge of a graph is represented as tuples of the table and saved in a database. We developed a library of graph operations for the storage and management of graphs and the development of graph applications. Furthermore, we defined graph algorithms in terms of relational algebraic operations such as projection, selection, and join. They can be implemented with the database language such as SQL. This database approach provides an efficient methodology to deal with very large-scale graphs and to support the development of graph applications.

• Proceedings of the Korean Information Science Society Conference
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• 2000.10a
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• pp.113-115
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• 2000

A GIS software GEO Millennium SystemTM has been developed to integrated with spatial database that combines conventional and spatially related data. As we known well the standard query language lacks the support of spatial data type and predicate, and can not serve as the query language in the spatial database directly; some extended strategies have been proposed, but some of them need their own storage manager, some introfuce new clause into the SELECT-FROM-WHERE structure, and some is very complex and available to us. So we designed our own query language on the conventional storage manager system. It supports the Spatial Data Type and predicate, and provides the full query capabilities of SQL on the non-spatial part of the database while being tightly integrated with the spatial part, without changing the standard SQL structure.

• The Journal of the Korea Contents Association
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• v.21 no.12
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• pp.84-94
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• 2021

Graph databases have been developed to efficiently store and query graph data composed of vertices and edges to express relationships between objects. Since the query types of graph database show very different characteristics from traditional NoSQL databases, benchmarking tools suitable for graph databases to verify the performance of the graph database are needed. In this paper, we propose an efficient graph database benchmarking system that supports diversity in graph inputs and queries. The proposed system utilizes OrientDB to conduct benchmarking for graph databases. In order to support the diversity of input graphs and query graphs, we use LDBC that is an existing graph data generation tool. We demonstrate the feasibility and effectiveness of the proposed scheme through analysis of benchmarking results. As a result of performance evaluation, it has been shown that the proposed system can generate customizable synthetic graph data, and benchmarking can be performed based on the generated graph data.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.12 no.7
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• pp.3227-3235
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• 2011

In this paper, a relational embedded DBMS was designed and a prototype 'Miracle' RDBMS (MDB) was developed. MDB is written in C and works on Unix, Linux and Windows platforms locally. It accesses database through SQL interfaces and API functions and uses $B^+$ tree index. It guarantees ACID in transactions and supports low concurrency control and processes SQL statements on a single table. To evaluate the performance of MDB on an ARM board EZ-S3C6410 and to compare the performance of MDB with that of SQLite, an experiment was carried out to estimate processing times for insertion, selection, update and deletion operations. The result shows that the average times for selections and insertions in MDB were 38.46% and 22.86% faster than those in SQLite, respectively, but the average times for updates and deletions in SQLite were 28.33% and 26.00% faster than MDB, respectively, This experiment shows that fetching data from database and sending data to database in MDB is faster than in SQLite, but $B^+$ tree index is implemented more effectively in SQlite than in MDB.

• The Journal of the Korea Contents Association
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• v.17 no.7
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• pp.93-100
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• 2017

Recently, demands for high-performance flash-based storage devices (i.e., flash SSD) have rapidly grown in social network services, cloud computing, super-computing, and enterprise storage systems. The industry and academic communities made the NVMe specification for high-performance storage devices, and NVMe-based flash SSDs can be now obtained in the market. In this article, we evaluate performance of NoSQL databases that social network services and cloud computing services heavily adopt by using NVMe-based flash SSDs. To this end, we use NVMe SSD that Samsung Electronics recently developed, and the SSD used in this study has performance up to 3.5GB/s for sequential read/write operations. We use WiredTiger for NoSQL databases, and it is a default storage engine for MongoDB. Our experimental results show that log processing in NoSQL databases is a major overhead when high-performance NVMe-based flash SSDs are used. Furthermore, we optimize components of log processing and optimized WiredTiger show up to 15 times better performance than original WiredTiger.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.12 no.7
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• pp.3375-3400
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• 2018

With the advent of database-as-a-service (DAAS) and cloud computing, more and more data owners are motivated to outsource their data to cloud database in consideration of convenience and cost. However, it has become a challenging work to provide security to database as service model in cloud computing, because adversaries may try to gain access to sensitive data, and curious or malicious administrators may capture and leak data. In order to realize privacy preservation, sensitive data should be encrypted before outsourcing. In this paper, we present a secure and practical system over encrypted cloud data, called QSDB (queryable and secure database), which simultaneously supports SQL query operations. The proposed system can store and process the floating point numbers without compromising the security of data. To balance tradeoff between data privacy protection and query processing efficiency, QSDB utilizes three different encryption models to encrypt data. Our strategy is to process as much queries as possible at the cloud server. Encryption of queries and decryption of encrypted queries results are performed at client. Experiments on the real-world data sets were conducted to demonstrate the efficiency and practicality of the proposed system.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2017.10a
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• pp.744-747
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• 2017

The Internet of things (IoT) needs to be an event-driven approach for efficient real time response and processing. An IoT gateway is sometimes employed to provide the connection and translation between devices and the cloud. Storing data in the local database, and then forwarding it on the cloud is a task to be relegated to a gateway device In this paper, we propose the design of the IoT gateway with Fog computing for storing data from sensors into a local database. In the procedure of designing storing tasks, we propose to use the interfacing software known as Ardulink MQTT bridge. MQTT is a protocol for sensors to publish data to the clients. When it comes to needing historical data, MQTT connector can push MQTT data into SQL database. We write an MQTT client and based on the message topic insert the values into a SQL Database The design of IoT gateway with Fog computing adds value because it provides processing of the data across multiple devices before it sends to the cloud.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2007.02a
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• pp.165-168
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• 2007

정보화 사회에서 사용자의 민감한 정보를 보호하는 가장 확실한 방법은 데이터의 암호화이다. 지금까지 암호화된 데이터에 대해 제안되어진 대부분의 기법들은 모든 종류의 SQL 쿼리가 가능하지 않았고 암호화 기법이나 효율성 등 다양한 측면에서 문제점을 가지고 있었다 본 고에서 제안하는 기법인 PPSQL은 'Perfect Unlinkability'를 보장한다. 이것은 데이터 자체를 암호화하는 것이 아니라 그 데이터의 열의 위치를 치환시킴으로써 데이터와 그 데이터 소유자와의 관계를 끊어버린다. 이렇게 데이터 자체를 암호화시키지 않음으로써 클라이언트가 쿼리를 만드는 방법이나 서버가 프로세스 하는 방법이 일반 DB와 거의 유사하다. 단지 셋업 시 암호화된 DB를 구축할 때와 서버에 의해 리턴된 결과를 클라이언트가 복호화 할 때의 추가적인 연산만이 필요하다. 또한 우리의 기법은 산술 연산이 가능하고 암호화된 데이터의 속성들 간의 교차 연산을 제외하고는 모든 종류의 SQL 쿼리가 가능하다.

• Proceedings of the Korean Information Science Society Conference
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• 2000.04b
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• pp.84-86
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• 2000

XML은 다양한 정보이 표현이 가능하고 이들 정보의 구조적 표현이 가능하여 많은 연구 분야에서 사용되고 있다. 이러한, XML 문서의 효율적인 검색과 저장 관리를 위하여 데이터베이스 시스템을 이용한 연구가 활발히 진행되고 있으나 기존의 연구들은 XML 문서에 대한 질의 수행을 위해 SQL 과 독립된 질의 언어를 정의함으로써 데이터베이스와 통합된 질의를 제공하지 못한다. 본 논문에서는 XML 문서와 데이터베이스의 통합된 질의를 위하여 XML 문서의 엘리먼트를 자료형으로 정의하는 DDL 구문의 추가와 질의어에서 이들 자료형에 대한 연산을 지원하는 DML 의 확장을 한다. 제안한 질의어는 SQL을 이용하여 XML 문서에 대한 질의를 처리함으로써 XML 문서와 데이터베이스의 통합된 질의를 가능하게 한다.