• Proceedings of the Korean Information Science Society Conference
• /
• 2008.06d
• /
• pp.377-382
• /
• 2008

본 논문에서는 대역폭의 감소를 가능하게 하는 프레임 드로핑을 MPEG-4파일 포맷을 따르는 미디어에 적용 했을 때, 암호화를 통하여 저작권을 보호할 수 있는 방법을 제안하였다. 프레임 드로핑은 특정 비디오 프레임을 제거함으로써 서버의 과부하를 줄이는 방법이다. 프레임 간의 종속성이 가장 적은 B 프레임을 먼저 제거하고 종속성의 관계에 따라 I, P 프레임 순서대로 제거한다. 드로핑 된 파일을 서버에 저장후 전송하는 방법과 전송 시에 실시간 드로핑을 이용하여 전송하는 두 가지 방법을 설계하였다. MPEG-4 데이터의 암호화에는 3가지 방법을 설계하였고, 블록암호화 알고리즘은 DES(Data Encryption Standartd)를 사용하였다. 이러한 방법으로 MPEG-4 스트리밍 서비스 시에 서버의 DRM 솔루션을 구현하고, 최적의 방법을 선택하기 위해 드로핑, 암호화, 복호화 및 영상의 품질을 비교하였다.

• Proceedings of the KIEE Conference
• /
• 2001.07a
• /
• pp.65-67
• /
• 2001

Because of the difficulty of acquiring new generation sites and right- of-way, additional units have been added to the existing generation sites and the transmission system has been developed into highly meshed configuration. The reliable operation of power systems has been restricted by this system characteristics. The enhancement of system analysis techniques and establishment of appropriate measures have been required in this situation. In addition the deregulation of electric power industry in Korea would give rise to better tools for power system analysis and control. In this paper, dynamic models were developed.

• Proceedings of the KIEE Conference
• /
• 2001.07a
• /
• pp.68-70
• /
• 2001

Because of the difficulty of acquiring new generation sites and right- of-way, additional units have been added to the existing generation sites and the transmission system has been developed into highly meshed configuration. The reliable operation of power systems has been restricted by this system characteristics. The enhancement of system analysis techniques and establishment of appropriate measures have been required in this situation. In addition the deregulation of electric power industry in Korea would give rise to better tools fur power system analysis and control. In this paper, dynamic models were developed and stability studies were implemented using developed dynamic models of EUROSTAG and compared with the simulation results of PSS/E.

• Journal of electromagnetic engineering and science
• /
• v.11 no.4
• /
• pp.290-297
• /
• 2011

Recent progresses in the live electrooptic imaging (LEI) technique are reviewed with emphasis on its functionality of real-time visual accesses to traveling electric waves in the GHz range. Together with the principles, configurations, and procedures for the visual observation experiments by an LEI camera system, the following results are described as examples indicating the wide application ranges of the technique; Ku-band waves on arrayed planar antennas, waves on a Gb/s-class digital circuit, W-band waves traveling both in slab-waveguide modes and aerially, backward-traveling wave along composite right/left-handed transmission line, and, waves in monolithic microwave integrated circuit module case.

• Journal of electromagnetic engineering and science
• /
• v.13 no.4
• /
• pp.245-250
• /
• 2013

This paper presents a tunable bandpass filter based on the varactor-loaded composite right- and left-handed transmission line (CRLH-TL). The proposed filter is composed of one CRLH-TL unit cell, which corresponds to the third-order bandpass filter. The tunable bandpass filter is designed using only lumped-elements. The use of lumped elements saves space and lowers the fabrication cost. The size of the proposed tunable bandpass filter is $17mm{\times}5mm$, neglecting the feed lines and DC lines. All of the varactors are controlled by one DC bias. The center frequency of the bandpass filter can be controlled by varying the value of the varactors. The tunable range of the center frequency is from 412.5 to 670 MHz. The insertion loss is less than 3 dB, the return loss is more than 10 dB in the passband.

• Journal of electromagnetic engineering and science
• /
• v.15 no.1
• /
• pp.31-36
• /
• 2015

The design of a new compact band-pass filter is proposed, which is based on the microstrip composite right- and left-handed transmission- line (CRLH-TL) structure. Particularly, the interdigital coupled (IDC) lines of the CRLH geometry are proposed to be parted by inserting open stubs to meet the specifications on the passband. In addition, there is another pair of stubs to complete the design in a limited space. These are considered in the TL-based analysis and the design parameters are calculated by genetic algorithm optimization. The measurement is shown to be acceptable and agreeable with the circuit and electromagnetic field simulations. In addition, the zerothorder resonance (ZOR) phenomenon is verified.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.10 no.2
• /
• pp.271-275
• /
• 2006

In STP, network performance differs depending on topology configuration. Therefore, we need to configure right topology for the optimal efficiency of networking. This paper suggest the optimal topology configuration for efficient networking between ethernet switchs. It finds out the best topology configuration by calculation mathematical model which uses transmission time between root switch and other switchs in the same domain. And it also analysed performance difference on locations of root switch. Through the performance analysis, we could conclude that placing the root switch in the center is the most efficient.

• Journal of Electrical Engineering and Technology
• /
• v.9 no.3
• /
• pp.997-1001
• /
• 2014

In this paper, the interference in small MIMO antennas having two identical composite right- and left-handed transmission-line(CRLH-TL)-based radiating elements is remarkably decreased. The radiating element has the broadside-capacitive coupling as well as slots to be equivalent to the CRLH-TL to prevent the size from increasing for an LTE high band. The suspended line bridging the two radiating elements is optimized to lower the interference between them down to -23 dB, while the overall MIMO antenna system is compact and its antenna performance is acceptable. The design is tested for 2.5 GHz.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 1996.10a
• /
• pp.91-97
• /
• 1996

We have all heard sounds that did not sound "right" while riding in an automobile. Objectionable sounds are difficult to find and understand because the sound field is complex and dynamic in the near field of an automobile. Many different noise sources and transmission paths must be understood before an engineering change can be recommended. This paper reviews the fundamental characterization of sound and chscusses the Sound Intensity measurement technique. Sound intensity measurements locate sources and sinks of acoustic energy. Used with narrowband analysis equipment, acoustic noise sources can be identified. Sound intensity measurements are made -in-situ and do not require specmi anechoic facilities. The measurement results in a vector representation of the near field sound field and can discriminate between multiple sound sources.d sources.

• Structural Engineering and Mechanics
• /
• v.3 no.1
• /
• pp.11-23
• /
• 1995

The examined model consists of two substructures linked by a right angle rigid line joint. One element is a wall loaded externally along its upper edge by an uneven vertical load. The other element, defined as a plate, is not loaded. Stresses and displacements in the vicinity of the joint are analysed, considering the lateral distribution which leads to three-dimensional effects. The proposed solution combines classical approach with numerical means, using appropriate stress distribution polynomial functions along the joint. Space structure constructions supply cases of interest.