• The KIPS Transactions:PartA
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• v.18A no.6
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• pp.225-232
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• 2011

Restricted Hypercube-Like (RHL) graphs are a graph class that widely includes useful interconnection networks such as crossed cube, Mobius cube, Mcube, twisted cube, locally twisted cube, multiply twisted cube, and generalized twisted cube. In this paper, we show that for an m-dimensional RHL graph G, $m{\geq}4$, with an arbitrary faulty edge set $F{\subset}E(G)$, ${\mid}F{\mid}{\leq}m-2$, graph $G{\setminus}F$ has a hamiltonian path between any distinct two nodes s and t if dist(s, V(F))${\neq}1$ or dist(t, V(F))${\neq}1$. Graph $G{\setminus}F$ is the graph G whose faulty edges are removed. Set V(F) is the end vertex set of the edges in F and dist(v, V(F)) is the minimum distance between vertex v and the vertices in V(F).

• MALSORI
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• no.49
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• pp.63-75
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• 2004

Most existing telephone speech transmitted in current public networks is band-limited to 0.3-3.4 kHz. Compared with wideband speech(0-8 kHz), the narrowband speech lacks low-band (0-0.3 kHz) and high-band(3.4-8 kHz) components of sound. As a result, the speech is characterized by the reduced intelligibility and a muffled quality, and degraded speaker identification. Bandwidth extension is a technique to provide wideband speech quality, which means reconstruction of low-band and high-band components without any additional transmitted information. Our new approach considers to exploit harmonic synthesis method for reconstruction of low-band speech over the CELP coded speech. A spectral distortion measurement and listening test are introduced to assess the proposed method, and the improvement of synthesized speech quality was verified.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2004.11a
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• pp.53-56
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• 2004

H.264/AVC (baseline profile)은 MPEG-4 (simple profile)에 비하여 약 2배정도 향상된 압축 성능을 나타내는 것으로 알려져, DMB 방송, DVD 등에 사용될 예정이며, 다양한 멀티미디어 서비스에 사용될 차세대 비디오 압축 표준으로 인정받고 있다 하지만, 부호기의 복잡도는 MPEG-4 simple profile에 비하여 16배정도 높아져서, 실시간을 요구하는 서비스, 또는 임베디드 환경을 갖는 서비스에 사용하는데 심각한 제약을 갖는다. 따라서, 기존의 표준 코덱들을 대체하여 다양한 통신 환경에서 향상된 화질의 비디오 서비스를 제공하기 위해서는 코덱의 복잡도 개선이 매우 중요하다. 본 논문은 H.264/AVC 비디오 코덱을 임베디드 환경을 갖는 통신 서비스에 적용하기 위하여 코덱의 복잡도를 개선하기 위한 방법을 제시한다

• Journal of Communications and Networks
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• v.4 no.4
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• pp.321-335
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• 2002

Emergence of the fourth generation mobile communication system (4G system) is now in its dawn. This article proposes a perspective framework on the 4G system, and discusses various kinds of system aspects and technological requirements in terms of novel service features, spectrum management, radio access technologies, wired access integration, core network, and mobile terminal. The focus of the article is to define the scope and features of the 4G system in an overall system/network viewpoint. From the foreseeable development trends, it is highly expected that whatever emerges in the 4G system will be some kind of constantly evolving and grand recursive concatenation of all the existing system/network developments.

• Journal of Biomedical Engineering Research
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• v.27 no.6
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• pp.343-350
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• 2006

Medical magnetic stimulator generates strong magnetic field pulses. Clinical applications of the magnetic pulse are the stimulation of nervous system and the contraction of muscle. The unique source of the strong magnetic pulse is a capacitor-inductor resonator and this inductor generates a strong sinusoidal magnetic pulse by discharging the capacitor with high initial voltage. Continuous muscle contraction needs sequential generation of the magnetic pulses. However, to keep the magnitude of sequential pulses identical, an expensive high-voltage power supply have to support voltage drop of the capacitor between the pulses. A protection circuit between the supply and the resonator is necessary to protect the supply from reverse current caused by capacitor voltage reversal. In this paper, a new circuit structure of the magnetic stimulator adopting a low-frequency fly-back switching is proposed. The new circuit supports sequential pulse generation and allows the reverse current without damage. Performance of the new circuit is examined and a low-cost magnetic stimulator for urinary incontinence therapy is being developed using the presented method.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2004.11a
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• pp.113-116
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• 2004

T-DMB 서비스의 경우 무시할 수 없는 빈도로 자주 전송 오류가 발생할 가능성이 있으므로, 내부 비디오 코덱인 H.264/AVC는 이 전송 오류에 의한 영향을 극복하기 위한 방안을 갖추도록 설계되어야 한다. 본 논문은 이 경우에 대비하여, 오류 내성이 있는 새로운 부호화 모드 결정 기법을 제안한다. WCDMA 채널을 통한 전송 시뮬레이션을 통하여, 제안하는 부호화 모드 결정 기법을 적용하는 경우 오류 내성을 고려하지 않고 부호화 모드를 결정하는 경우에 비해서 고-복잡도의 경우에는 평균적으로 0.77dB, 저-복잡도의 경우에는 0.35dB의 재생화질 개선 효과가 있음을 보였다. 고-복잡도 부호화 모드 결정 기법의 경우는 H.263에서 제시된 고-복잡도 부호화 모드 결정 기법에 비해서 평균적으로 0.l1dB 개선된 값이다.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.45 no.5
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• pp.52-62
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• 2008

In this paper, we develop a method that changes the resolutions of images in an arbitrary block transform domain by using a filter that suits to the characteristics of the underlying images. To accomplish this, we represent each procedure resizing images in an arbitrary transform domain as matrix multiplications and we derive the matrix that scales the image resolutions from the matrix multiplications. The resolution scaling matrix is also designed to be able to select the up/down-sampling filter that suits the characteristics of the image. Experiments show that the proposed method produces the reliable performances when it is applied to various transforms and to images that are mixed with predicted and non-predicted blocks which are generated during video coding.

• Journal of Broadcast Engineering
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• v.10 no.4 s.29
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• pp.528-539
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• 2005

The H.264 has been adopted as the video codec for various multimedia services such as DMB and next-generation DVD because of its superior coding performance. However, the reference codec of the standard, the joint model (JM) contains quite a few algorithms which are too complex to be used for the resource-constraint embedded environment. This paper introduces very low-complexity H.264 encoding algorithm which is applicable for the embedded environment. The proposed algorithm was realized by restricting some coding tools on the basis that it should not cause too severe degradation of RD-performance and adding a few early termination and bypass conditions during the motion estimation and mode decision process. In case of encoding of 7.5fps QCIF sequence with 64kbpswith the proposed algorithm, the encoder yields worse PSNRs by 0.4 dB than the standard JM, but requires only $15\%$ of computational complexity and lowers the required memory and power consumption drastically. By porting the proposed H.264 codec into the PDA with Intel PXA255 Processor, we verified the feasibility of the H.264 based MMS(Multimedia Messaging Service) on PDA.

• The Journal of Korean Physical Therapy
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• v.21 no.3
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• pp.87-93
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• 2009

Purpose: TThis study examined the effect of repetitive magnetic stimulation (RMS) on the viability and proliferative response of human adipose tissue-derived stromal cells (hATSCs) in vitro. Methods: The hATSCs were cultured primarily from human adipose tissue harvested by liposuction and incubated in a $37^{\circ}C$ plastic chamber. The cells were exposed to a repetitive magnetic field using a customized magnetic stimulator (Biocon-5000, Mcube Technology). The RMS parameters were set as follows: repetition rate=10Hz, 25Hz (stimulus intensity 100%= 0.1 Tesla, at 4cm from the coil), stimulated time= 1, 5, and 20 minutes. Twenty four hours after one application of RMS, the hATSCs were compared with the sham stimulation, which were kept under the same conditions without the application of RMS. The cells were observed by optical microscopy to determine the morphology and assessed by trypan blue staining for cell proliferation. The apoptosis and viability of the hATSCs were also analyzed by fluorescence-activated cell sorting (FACS) analysis of Annexin V and MTT assay. Results: After RMS, the morphology of the hATSCs was not changed and the apoptosis of hATSCs were not increased compared to the sham stimulation. The viability of the cells was similar to the cells given the sham stimulation. Interestingly, the level of hATSC proliferation was significantly higher in all RMS groups. Conclusion: The application of RMS may not cause a change in morphology and viability of hATSCs but can increase the level of cell proliferation in vitro. RMS might be useful as an adjuvant tool in combination with stem cell therapy without adverse effects.