• Korean Journal of Optics and Photonics
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• v.10 no.6
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• pp.473-481
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• 1999

We propose a new scheme of hologram multiplexing that can improve the crosstalk noise in the conventional phase-code multiplexing. Our method is based on the idea that the separate holograms to be stored in a certain region of the photorefractve material should have relative phase other than $180^{\circ}$. To demonstrate the new idea we fabricate a phase spatial light modulator using piezo-electric material. The experimental result shows that the crosstalk noise in the restored holograms is reduced much in our method. We also computer simulate the hologram multiplexing and compare the result with the experimental data.l data.

• Proceedings of the Korea Information Processing Society Conference
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• 2011.04a
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• pp.3-6
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• 2011

IT 기술의 발전에 따른 전력 사용량 증가로 인해서 친환경 재생 에너지에 대한 관심이 집중되고 있는 상황으로 다양한 재생 에너지자원 가운데 풍력에너지 개발이 전 세계적으로 급속히 증가하고 있다. 그러나 풍력발전기를 제어하는 제어기의 소프트웨어·하드웨어적인 문제로 인해 불규칙한 에너지 생산과 유지보수를 위한 비용이 증가함에 따라 최근에는 풍력제어기의 고장분석 및 고장 감내 제어에 대한 연구가 활발히 진행되고 있는 상황이다. 본 논문에서는 이와 같은 풍력발전기가 지속적으로 일정한 에너지 생산과 유지보수 절감이 가능하도록 하기 위해 풍력제어시스템 차원에서의 고장에 대해서 감내 가능한 고가용성의 미들웨어에 대한 구조를 제안한다. 풍력제어시스템의 고 가용성 미들웨어는 가상 운영체제를 기반으로 이중화 구조를 가지고 있으며, 주 운영체제에서 소프트웨어적인 고장이 발생 시 다음 우선순위의 가상 운영체제에서 지속적인 서비스를 제공할 수 있도록 각각의 가상 운영체제 환경을 관리한다.

• The Journal of the Acoustical Society of Korea
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• v.23 no.1
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• pp.54-60
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• 2004

In order to mitigate the problems in storage space and network bandwidth for the full CD quality audio, current digital audio is always restricted by sampling rate and bandwidth. This restriction normally results in low sample rate audio or calls for the data compression scheme such as MP3. However, they can only reproduce a lower frequency range than a regular CD quality because of the Nyquist sampling theory. Consequently they lose rich spatial information embedded in high frequency. The propose of this paper is to propose efficient high frequency enhancement of low sample rate audio using n adaptive filtering and DWT analysis and synthesis. The proposed algorithm uses the LMS adaptive algorithm to estimate the missing high frequency contents in DWT domain and it then reconstructs the spectrally enhanced audio by using the DWT synthesis procedure. Several experiments with real speech and audio are performed and compared with other algorithm. From the experimental results of spectrogram and sonic test, we confirm that the proposed algorithm outperforms the other algorithm and reasonably works well for the most of audio cases.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.43 no.2 s.308
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• pp.28-32
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• 2006

In this paper, NTSC TV Transmitter Modulo will be designed and produced which make possible playing the motion picture not only on TV but also on portable TV. NTSC TV Transmitter Module modulates signals that received Video and Audio signals from a mobile on NTSC TV CH4 mechanism. so it has an advantage of convenience that watching the motion picture of mobile on TV without any other cable through transmitting signals by wireless. But it has some demerits of long size antenna and noise sensitiveness. In the future, if some problems like a size of antenna distortion of signal and noise can be solved through continuous researching about Radio Frequency part, it is possible to play mobile motion pictures on the more media like a camcorder, DVD player and so on.

• The Journal of the Korea institute of electronic communication sciences
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• v.6 no.1
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• pp.84-89
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• 2011

Musical sheet recognition is an emerging area as the role of computers in music increases. Although there are several well-known programs for composition, they have a limitation in that they cannot edit or play music generated from other programs. In this paper, we propose an algorithm that can read, recognize, and play music using printed sheets. The proposed algorithm first removes lines using horizontal histogram and extracts symbols. The symbols belong to one of the three categories; notes, rests, and other signs. Notes are recognized using the context information and rests and signs are recognized using a fuzzy ART algorithm. The proposed algorithm were applied to 50 pages of musical sheets and the experimental results showed that it is effective in automatic recognition of musical sheets.

• The KIPS Transactions:PartD
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• v.9D no.1
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• pp.57-64
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• 2002

Few studies have been systematically pursued on a multimedia data mining in despite of the overwhelming amounts of multimedia data by the development of computer capacity, storage technology and Internet. Based on the preliminary image processing and content-based image retrieval technology, this paper presents the methods for discovering association rules from recurrent items with spatial relationships in huge data repositories. Furthermore, multimedia mining algorithm is proposed to find implicit association rules among objects of which content-based descriptors such as color, texture, shape and etc. are recurrent and of which descriptors have spatial relationships. The algorithm with recurrent items in images shows high efficiency to find set of frequent items as compared to the Apriori algorithm. The multimedia association-rules algorithm is specially effective when the collection of images is homogeneous and it can be applied to many multimedia-related application fields.

• Asia-pacific Journal of Multimedia Services Convergent with Art, Humanities, and Sociology
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• v.6 no.3
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• pp.31-39
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• 2016

As the computer technology is developed, score-writers that can edit music have more improved functions. A user not only can insert notes, chords, and musical symbols conveniently, but also can listen to music displayed in the score. Existing commercial score-writers make scores look good and play notes through VSTi(Virtual Studio Technology instrument). However chord accompaniment function is so vulnerable that it is hard to know whether or not displayed chords are suitable for music. If a score-writer has a proper function that plays chord sound good to hear, it will be a good reference to band music sheet writers. In this paper, to improve chord playback function in existing score-writers, we propose an algorithm that selects suitable chord tones for chord playback and implemented a program. If we apply this algorithm, the chord play function of a score-writer will be strengthened and resultantly a music sheet writer who makes a band music can make scores more conveniently.

• Korean Journal of Optics and Photonics
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• v.15 no.4
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• pp.299-308
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• 2004

We proposed more efficient encoding methods that can design a multi-channel multi-level phase only computer-generated hologram(CGH) that can reconstruct many objects simultaneously without a conjugate image. We used a fabrication technique for the pixel oriented CGH for designing the pattern of the proposed multi-channel CGH. We investigated the difference of the optical efficiency(η), mean square error(MSE) and signal-to-noise ratio(SNR) of multi-channel CGHs that were designed by three kinds of encoding methods according to the number of quantization phase levels, and we estimated the performance of the pattern of the proposed multi-channel CGH. Generally, as the number of input objects' reference patterns stored in the CGH is increased, the reconstruction quality of the CGH is degraded. But we observed through computer simulation that the diffraction efficiency of the 1-ch CGH is 70%, and those of the 2-ch, 4-ch, 8-ch CGHs are 62%, 62% and 63%. Therefore we found that the diffraction efficiencies of the multi-channel CGHs using the newly proposed encoding method are similar to that of 1-ch CGH. We implemented the CGH optically using a liquid crystal spatial light phase modulator that consisted of a PAL-SLM efficiently coupled with a XGA type LCD by an optical lens and an LD for illuminating the LCD. We discussed the output images that are reconstructed from the PAL-SLM.

• The KIPS Transactions:PartB
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• v.9B no.2
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• pp.181-190
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• 2002

This paper proposes a motion-video multimedia system needed for computer applications like remote lecturing, distance learning, product demonstrations, and so on. The applications need a multimedia system which can author and play a motion-Video that is composed with computer screen images and audio continuously varing as time flows, not with real motion videos. Since the computer screen images are not like the real world video images in several rejects, MPEG is not competent as a compression algorithm for computer screen images raring continuously In this paper a new compression algorithm has been proposed, and a multimedia system that authors and plays a motion-video file which contains computer screen images and audio has been implemented. Also this paper shows the result of performance evaluation of both the compression algorithm and the multimedia system implemented in the paper.

• Korean Journal of Optics and Photonics
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• v.16 no.1
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• pp.43-49
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• 2005

In this paper, we propose a method for optimizing a computer-generated hologram(CGH) by combining the Tabu Search(TS) algorithm with the Simulated Annealing(SA) algorithm. By replacing an initial random pattern of the SA algorithm with an approximately ideal hologram pattern of the TS algorithm, we design a CGH which has high diffraction efficiency(DE). We compared the performance of the proposed algorithm with the SA algorithm using computer simulation and an optical experiment. As a result, we confirmed diffraction efficiency and uniformity to be enhanced in the proposed algorithm.