• International Journal of Computer Science & Network Security
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• v.22 no.7
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• pp.427-442
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• 2022

MP3 is one of the most widely used file formats for encoding and representing audio data. One of the reasons for this popularity is their significant ability to reduce audio file sizes in comparison to other encoding techniques. Additionally, other reasons also include ease of implementation, its availability and good technical support. Steganography is the art of shielding the communication between two parties from the eyes of attackers. In steganography, a secret message in the form of a copyright mark, concealed communication, or serial number can be embedded in an innocuous file (e.g., computer code, video film, or audio recording), making it impossible for the wrong party to access the hidden message during the exchange of data. This paper describes a new steganography algorithm for encoding secret messages in MP3 audio files using an improved least significant bit (LSB) technique with high embedding capacity. Test results obtained shows that the efficiency of this technique is higher compared to other LSB techniques.

• International Journal of Internet, Broadcasting and Communication
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• v.14 no.3
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• pp.1-7
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• 2022

This paper aims to compare the mean object size of M/G/1/PS model with that of M/BP/1 model used in the web service. The mean object size is one of important measure to control and manage web service economically. M/G/1/PS model utilizes the processor sharing in which CPU rotates in round-robin order giving time quantum to multiple tasks. M/BP/1 model uses the Bounded Pareto distribution to describe the web service according to file size. We may infer that the mean waiting latencies of M/G/1/PS and M/BP/1 model are equal to the mean waiting latency of the deterministic model using the round robin scheduling with the time quantum. Based on the inference, we can find the mean object size of M/G/1/PS model and M/BP/1 model, respectively. Numerical experiments show that when the system load is smaller than the medium, the mean object sizes of the M/G/1/PS model and the M/BP/1 model become the same. In particular, when the shaping parameter is 1.5 and the lower and upper bound of the file size is small in the M/BP/1 model, the mean object sizes of M/G/1/PS model and M/BP/1 model are the same. These results confirm that it is beneficial to use a small file size in a web service.

• Journal of the Korean Institute of Telematics and Electronics A
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• v.31A no.10
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• pp.21-30
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• 1994

We discussed the Distributed Control System's design on preface and analyzed time of the real-time communication by using designed system. The DCS proposed in this thesis was implemented to network file system having recovery advantage and shared memory method to access file system of a Remote Station with ease. Also, this system minimized the network delay-time by using the real-time VME147 board. In implemented DCS, the performance analysis of real-time process of a Remote Station was done to get the total time for reak-tune communication from a Remote Station to the Central Station after terminating of process. For the analysis of system performance, we experiented by three steps. Firstly, we measuredthe processing the of LOOP function that real-time CPU convertes to-2,500~10.000 values from the input data of the Analog Interface Card. Secondly, we measured the processing time of the LOGIC function and the LOOP function. Lastly, we measured total processing time for communication from a Remote Station to the Centrol Station.

• 한국정보통신설비학회:학술대회논문집
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• 2004.08a
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• pp.124-127
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• 2004

최근 인터넷의 급속한 발전과 함께 인터넷에 접속되는 서버의 수가 기하 급수적으로 증가하고 있다. 이러한 인터넷의 보급과 함께 중요한 문제로 부각되는 것이 보안 문제이다. 최근 서버를 리눅스(Linux)로 구축하는 사례가 늘고 있다. 본 논문에서는 현재 널리 사용되고 있는 리눅스의 파일시스템을 보안적인 차원에서 문제점이 무엇인지 분석하고 이를 해결하는 방안으로 리눅스 커널 레벨에서 동작하는 새로운 리눅스 보안 파일시스템을 구현하였다.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 1992.04b
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• pp.476-485
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• 1992

기업간에 교환되는 문서를 EDI의 자료 구조를 이용하여 효율적으로 전송하고 저장할 수 있다. 본 연구는 이를 위한 변환 처리 스프트웨어인 KU-EDI를 이용하여 작성되는 메시지들에 대한 통신처리를 위한 통신 프로토콜에 관한 연구이다. EDI시스템을 지원하는 프로토콜들인 X.400MHS(Message Handling System), X.435 PEDI, FTAM(File Transfer Access Management), X.25, Odette FTP(File Transfer Protocol)들에 관해 조사 연구 및 비교분석을 하였다. KU-EDI를 위한 통신 프로토타입 모델로서 현재 EDI를 가장 잘 지원해 주는 OSI의 MHS에 기초하여 UA(User Agent), MS(Message Store), 그리고 MTA(Message Transfer Agent)로 구분을 해서 시스템을 설계하고 구현했다. 이 EDI/MHS모델에서 UA, MS, MTA는 한 시스템내에서 상호작용 한다.

• Journal of the Korea Society for Simulation
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• v.12 no.2
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• pp.25-34
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• 2003

Because of explosive growth in demand for web-based multimedia applications, proper proxy caching for large multimedia object (especially video) has become needed. For a video object which is much larger in size and has different access characteristics than the traditional web object such as image and text, caching the whole video file as a single web object is not efficient for the proxy cache. In this paper, we propose a proxy caching strategy with the constant-sized segment for video file and an improved proxy cache replacement policy. Through the event-driven simulation under various conditions, we show that our proposal is more efficient than the variable-sized segment strategy which has been proven to have higher hit ratio than other traditional proxy cache strategies.

• The Journal of Society for e-Business Studies
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• v.3 no.1
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• pp.1-22
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• 1998

SDAI (Standard Data Access Interface) is an interface specification of accessing various storage systems such as file systems and database management systems for STEP data. Using SDAI, both application program developers and CAD/CAM system developers can be relieved from dealing with STEP physical file or system dependent DBMS operations. In this paper, we present implementations of SDAI on different data models, i.e., relational, extended relational, and object-oriented. In order to implement SDAI, we need to translate the EXPRESS information model into target data models. The schema translation process for three different data models are compared and other implementation issues are discussed.

• Proceedings of the KIEE Conference
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• 2001.07d
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• pp.2678-2680
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• 2001

We develop a total solution system for applications, which is called a data processing module system(DPMS), based on ASP, PDF, JAVA, and MSSQL. The DPMS system provides a realtime telematic guidance in the fields of application, recruiting, and management. The user documents the PDF file on the Web browser and store the file in DB for correction. The DPMS discovered the difficulties in data input due to 2 byte problem of Korean language. This result leads to the usage of Korean language as well as others. Test results through free-charge access confirm that the DPMS outperforms the conventional systems based on ASP with HTML in view of simplicity and confidentiality.

• International Journal of Computer Science & Network Security
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• v.23 no.2
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• pp.89-95
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• 2023

Cloud computing today provides huge computational resources, storage capacity, and many kinds of data services. Data sharing in the cloud is the practice of exchanging files between various users via cloud technology. The main difficulty with file sharing in the public cloud is maintaining privacy and integrity through data encryption. To address this issue, this paper proposes an Enhanced RSA encryption schema (ERSA) for data sharing in the public cloud that protects privacy and strengthens data integrity. The data owners store their files in the cloud after encrypting the data using the ERSA which combines the RSA algorithm, XOR operation, and SHA-512. This approach can preserve the confidentiality and integrity of a file in any cloud system while data owners are authorized with their unique identities for data access. Furthermore, analysis and experimental results are presented to verify the efficiency and security of the proposed schema.

• The Transactions of the Korea Information Processing Society
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• v.6 no.5
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• pp.1189-1202
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• 1999

As compared with VOD data, NOD article data has the following characteristics: it is created at any time, has a short life cycle, is selected as not one article but several articles by a user, and has high access locality in time. Because of these intrinsic features, user access patterns of NOD article data are different from those of VOD. Thus, building NOD system using the existing techniques of VOD system leads to poor performance. In this paper, we analysis the log file of a currently running electronic newspaper, show that the popularity distribution of NOD articles is different from Zipf distribution of VOD data, and suggest a new popularity model of NOD article data MS-Zipf(Multi-Selection Zipf) distribution and its approximate solution. Also we present a life cycle model of NOD article data, which shows changes of popularity over time. Using this life cycle model, we develop LLBF (Largest Life-cycle Based Frequency) prefetching algorithm and analysis he performance by simulation. The developed LLBF algorithm supports the similar level in hit-ratio to the other prefetching algorithms such as LRU(Least Recently Used) etc, while decreasing the number of data replacement in article prefetching and reducing the overhead of the prefetching in system performance. Using the accurate user access patterns of NOD article data, we could analysis correctly the performance of NOD server system and develop the efficient policies in the implementation of NOD server system.