• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.15 no.3
• /
• pp.301-310
• /
• 2004

In this paper, a compact dual-mode filter structure without coupling gaps is proposed. The novel design is achieved by embedding a pair of equal crossed slots and spur-lines. Without coupling gaps between feed lines and patch resonator, the new filter can provide low insertion loss. It is found that this design has wide coupling range for dual-mode operation. It means that these characteristics of the proposed filter can reduce uncertainty in fabrication. By using two PIN diodes mounted inside a pair of spur-lines, the proposed structure works as a switchable filter. Also, it has a size reduction of about 34.7 %, compared with conventional dual-mode filters.

• Proceedings of the Korean Society of Propulsion Engineers Conference
• /
• 2017.05a
• /
• pp.277-284
• /
• 2017

This study is the results of the analytical research for a dual-model scramjet engine flowpath which is included inlet, isolator, combustor, and nozzle. To design a dual-mode scramjet engine and to investigate its performance, the performance analysis models and tools are required to develope for aerodynamic, thermodynamic characteristics, propulsion, and total system. Therefore, analysis models for air inlet, isolator, supersonic combustor, and nozzle of a dual-mode scramjet engine were accomplished, the performance characteristics of a dual-mode scramjet engine is investigated with using the developed analysis tools.

• Journal of KIISE:Computing Practices and Letters
• /
• v.15 no.4
• /
• pp.280-283
• /
• 2009

To improve coding performance of scalable video coding which is an emerging video coding standard as an extension of H.264/AVC, SVC uses not only intra prediction and inter prediction but inter-layer prediction. This causes a problem that computational complexity is increased. In this paper, we propose an efficient intra prediction mode decision method in spatial enhancement layer to reduce the computational complexity. The proposed method selects Inra_BL mode using RD cost of Intra_BL in advance. After that, intra mode is decided by only comparing DC modes. Experimental results show that the proposed method reduces 59% of the computation complexity of intra prediction coding, while the degradation in video quality is negligible.

• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.43 no.5
• /
• pp.466-471
• /
• 2015

In this paper, the design technique of the wide swath TOPS(Terrain Observation by Progressive Scan) imaging mode is introduced. The TOPS mode overcomes the scalloping limitations imposed by ScanSAR mode by steering the antenna pattern along track direction during the acquisition of a burst. This paper reports the operation concept of TOPS imaging and mode design result to extract the SAR operational parameters. Finally, several analyzed results such as IRF(Impulse Response Function), NESZ(Noise Equivalent Sigma Zero) and DTAR(Distributed Target Ambiguity Ratio) are presented.

• Journal of the Institute of Electronics Engineers of Korea SP
• /
• v.41 no.6
• /
• pp.165-173
• /
• 2004

H.264 is the newest international video coding standard that provides high coding efficiency. A macroblock in H.264 has 7 different motion-compensation block sizes in the Inter mode, and several different prediction directions in the Intra mode. In order to achieve as highest coding efficiency as possible, H.264 reference model employs complex mode decision technique based on rate-distortion (RD) optimization which requires high computational complexity. In this paper, we propose two techniques -'early SKIP mode decision' and 'selective intra mode decision' - which can further reduce the computational complexity. Simulation results show that without considerable performance degradation, the proposed methods reduce encoding time by 30% on average and save the number of computing rate-distortion cost by 72%.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.30 no.12C
• /
• pp.1144-1152
• /
• 2005

Intra prediction coding is one of the many coding-efficiency oriented tools of H.264/AVC, but it requires high computational complexity. Many fast intra coding algorithms have been proposed to reduce the computational complexity of intra prediction. While most of them have been focused on the mode decision methods themselves, we propose a fast algorithm in which new intra modes are substituted for the conventional intra modes so that the number of intra modes can be reduced. The simulation results show that the proposed method could reduce the encoding time of the overall sequence by $49\%$ without any noticeable degradation of the coding efficiency.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.29 no.5 s.236
• /
• pp.716-725
• /
• 2005

The method of substructure synthesis o. component mode synthesis(CMS) provides an effective means of dynamic analysis of very large and/or complex structures. In this study, residual dynamic flexibility attachment modes in hybrid component mode synthesis are considered for the purpose of exactly compensating the effect of higher order truncated modes. Following this way, the analysis accuracy of the synthesized structure can be improved effectively with less computational effort. In order to show the accuracy and effectiveness of the proposed hybrid component mode synthesis(HCMS), numerical experiments were carried out for the models of a clamped-clamped beam. The results verified the effectiveness of the proposed method.

• Korean Journal of Optics and Photonics
• /
• v.5 no.4
• /
• pp.466-472
• /
• 1994

An Argon laser pumped Ti:Sapphire laser has been constructed and self-mode locked. Mode-locking was initiated by a moving mirror mounted on the ball slider and maintained by the self-focusing in the laser crystal and an aperture inside the resonator. A prism pair was used to reduce group velocity dispersion. The bandwidth and the pulse width of the mode-locked pulse were 11 nm, $1000\pm20fs$, respectively. ively.

• Convergence Security Journal
• /
• v.8 no.4
• /
• pp.153-159
• /
• 2008

Graded-Index Multimode Optical fibers have recently received a lot of attention as regards their application and lightwave behavior in relation to broadband communication links. Accordingly, this aticle presents a novel lightwave mode analysis that solves the wave equation using a numerical analysis based on an eigenvalue problem method, thereby avoiding the typical complicated Bessel function method. Angular depedences and number of modes were observed as well. Future research implications will be possibly noticed such areas as bending effects and mode coupling analyses thru this research.

• Transactions of the Korean Society of Mechanical Engineers
• /
• v.15 no.3
• /
• pp.824-833
• /
• 1991

본 연구에서는 차체구조계의 진동모드 변수와 차실음향계의 음향모드변수들이 어떻게 관련되어 차실소음을 결정하는 가를 밝혔다. 그 결과, 수치해석 결과의 효용 성을 높이고 실내소음 평가방법을 체계화 시킬 수 있었으며, 효과적인 소음저감을 위 한 유용한 자료를 얻을 수가 있었다. 한편, 이제까지의 차실소음의 응답해석에서 가 장 큰 오차의 발생요인은 차체의 구조진동 모드데이타인데, 본 연구에서는 유한요소해 석 대신 모드시험 결과를 이용함으써, 유한요소 모델리이 어려운 경우의 소음 해석의 신뢰도를 높일수가 있었다.