• Journal of Broadcast Engineering
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• v.2 no.1
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• pp.8-15
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• 1997

In this paper, a real-time operating Motion Picture Experts Group-1 (MPEG-1) audio encoder system is implemented using a TMS320C31 Digital Signal Processor (DSP) chip. The basic operation of the MPEG-1 audio encoder algorithm based on audio layer-2 and psychoacoustic model-1 is first verified by C-language. It is then realized using the Texas Instruments (Tl) assembly in order to reduce the overall execution time. Finally, the actual BSP circuit board for the encoder system is designed and implemented. In the system, the side-modules such as the analog-to-digital converter (ADC) control, the input/output (I/O) control, the bit-stream transmission from the DSP board to the PC and so on, are utilized with a field programmable gate array (FPGA) using very high speed hardware description language (VHDL) codes. The complete encoder system is able to process the stereo audio signal in real-time at the sampling frequency 48 kHz, and produces the encoded bit-stream with the bit-rate 192 kbps. The real-time operation capability of the encoder system and the good quality of the decoded sound are also confirmed using various types of actual stereo audio signals.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2009.05a
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• pp.63-67
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• 2009

In RFID system, Tag's Identification data is processed in host computer by application program. Example of application program is parking administration program, library state program etc.. Tag's ID that is recognized in reader is inputted to the Host computer. Application program of computer searches data in DB of computer such as Tag ID. After finding the same ID, host computer send to control command to driver H/W in accordance with application purpose. But, It need to confirm in long distance whether achievement process is acted normally. There will be the 2 methods, when we monitors the process in long distance. One is wired monitoring system, another is wireless monitoring system. Among wire method, internet communication network is useful. RFID system manufacture first in this treatise. RFID system Embody using EM4095 chip that is doing 125KHz by carrier wave. Tag's characteristic ID is sent in remote place through module that use W3100A chip. This system Manufacture, and data send-receive confirmed using simple application program. Reception confirm by result, and pictures show by whole system and each part. And a control program explained of each part.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.36 no.2A
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• pp.114-126
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• 2011

Video streaming over wireless multi-hop networks(WMNs) contains the following challenges from channel fading and variable bandwidth of wireless channel, and it cause degradation of video streaming performance. To overcome the challenges, currently, WMNs can use Forward Error Correction (FEC) mechanism. In WMNs, traditional FEC schemes, E2E-FEC and HbH-FEC, for video streaming are applied, but it has long transmission delay, high computational complexity and inefficient usage of resource. Also, to distinguish network status in streaming path, it has limitation. In this paper, we propose monitoring-based coordination of network-adaptive hop-to-end(H2E) FEC scheme. To enable proposed scheme, we apply a centralized coordinator. The coordinator has observing overall monitoring information and coordinating H2E-FEC mechanism. Main points of H2E-FEC is distinguishing operation range as well as selecting FEC starting node and redundancy from monitored results in coordination. To verify the proposed scheme, we perform extensive experiment over the OMF(Orbit Measurement Framework) and IEEE 802.1la-based multi-hop WMN testbed, and we carry out performance improvement, 17%, from performance comparison by existing FEC scheme.

• Journal of KIISE:Information Networking
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• v.35 no.5
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• pp.437-452
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• 2008

IEEE 802.16j MR networks introduce RSs (Relay Stations) within the IEEE 802.16 system in order to enhance the data throughput and extend the coverage. However, the current standardization defines that the BS (Base Station) controls MS's (Mobile Station's) handover, not only it induces the large signaling overhead but also handover latency could increase. In this paper, we propose a handover protocol in the MR networks where the high capability RSs that can process the MS's control functions are deployed. First, we classify the handover scenarios for the MR networks with the high capability RSs. Then, we define the MAC handover procedure, corresponding MAC management messages and the transmission routes for the proposed messages so that an 802.16e MS can perform seamless handover without noticing it is attached to an MR network. The simulation results show that the proposed handover protocol not only reduces the MAC management message overhead transferred through the wireless links compared to IEEE 802.16j/D1, which is the current standard for MR networks, but also performs the rapider and more secure MS handover than IEEE 802.16e and IEEE 802.16j/D1.

• 전자공학회논문지 IE
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• v.46 no.4
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• pp.1-7
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• 2009

The final goal of ITS and ETC will be to improve the traffic efficiency and mobile safety without new road construction. DSRC system is emerging nowadays as a solution of them. China DSRC standard which was released in May 2007 has low bit rate, short message and simple MAC control. The DSRC system users want a long lifetime over 1 year with just one battery. In this paper, we propose the SoC of very low power consumption architecture. Several digital logic concept and analog power control logics were used for very low power consumption. The SoC operation mode and clock speed, operation voltage range, wakeup signal detector, analog comparator and Internal Voltage Regulator & External Power Switch were designed. We confirmed that the SoC power consumption is under 8.5mA@20Mhz, 0.9mA@1Mhz in active mode, and under 5uA in power down mode, by computer simulation. The design of SoC was finished on Aug. 2008, and fabricated on Nov. 2008 with $0.18{\mu}m$ CMOS process.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.35 no.3B
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• pp.380-389
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• 2010

Since the internet is intend to be the best effort service, the system that stream a large amount of high quality medias need a techniques to overcome the network status for implementation. In this paper, we design and implement a method that estimate quickly whether network permits the needed bandwidth of media and a method that control QoS through that. Presented system uses Relative One-Way Delay(ROWD) trend in the case of the former, and leverages temporal encoding among Scalable Video Coding(SVC) that is apt to apply real time comparatively in the case of the latter. The streaming server classifies the medias by real time to several rates and begins transmission from top-level and is reported ROWD trend periodically from the client. In case of the server reported only 'Increase Trend', the sever decides that the current media exceeds the available bandwidth and downgrades the next media level. The system uses probe packet of difference quantity of the target level and the present level for upgrading the media level. In case of the server reported only 'No Increase Trend' by the ROWD trend response of the probe packet from client, the media level is upgraded. The experiment result in a fiber to the home(FTTH) environment shows progress that proposed system adapts faster in change of available bandwidth and shows that quality of service also improves.

• Journal of KIISE:Information Networking
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• v.33 no.4
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• pp.289-298
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• 2006

Algorithms for application-level multicast often use trees to deliver data from the source to the multiple receivers. With the tree structure, the throughput experienced by the descendant nodes will be determined by the performance of the slowest ancestor node. Furthermore, the failure of an ancestor node results in the suspension of the session of all the descendant nodes. This paper focuses on the transmission of data using multiple virtual forwarders, and suggests a scheme to overcome the drawbacks of the plain tree-based application layer multicast schemes. The proposed scheme elects multiple forwarders other than the parent node of the delivery tree. A receiver receives data from the multiple forwarders as well as the parent node and it can increase the amount of receiving data per time unit. The multiple forwarder helps a receiver to reduce the impact of the failure of an ancestor node. The proposed scheme suggests the forwarder selection algorithm to avoid the receipt of duplicate packets. We implemented the proposed scheme using MACEDON which provides a development environment for application layer multicast. We compared the proposed scheme with Bullet by applying the implementation in PlanetLab which is a global overlay network. The evaluation results show that the proposed scheme enhanced the throughput by 20 % and reduced the control overhead over 90 % compared with Bullet.

• 전기의세계
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• v.24 no.4
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• pp.42-51
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• 1975

전기공학은 그 분야가 광범위하면서 세분된 여러 소분야로 구성되어 있기 때문에 이를 간단한 몇마디로 표현하기는 불가능하다. 그러나 전기기술자는 전하를 위시하여 전하간의 힘 및 전하간의 에너지 교환에 관하여 주로 관여하게 된다. 즉 전기기술자는 전기적 에너지 및 정보의 발생, 전송, 기억 및 제어를 최적화할 책임이 있고, 그 분야는 부단히 팽창일로에 있으며 변해가고 있다. 즉 학문적인 기초이론 뿐만아니라 실제 응용분야인 산업분야에서도 눈부신 발전과 변화를 가져왔다. 현대산업 및 기술구조의 질적개선은 기술 반감기의 감소, 막대한 양의 정보처리, 시스템의 대형화, 복잡화 현상을 가져왔으며 기술자체가 사회경제활동에 미치는 영향을 극대화시켰다. 그러므로 오늘날의 모든 전기기술자들은 신뢰성을 고려한 보다 넓은 의미에서의 책임을 느껴야 한다. 조국의 근대화와 방위산업육성 과정에서 중추적 역할을 담당할 이러한 전기공학분야의 중견연구원 및 기술자를 양성하는 공과대학전기공학과의 교과과정 역시 부단히 변하는 각종 환경에 적응될 수 있는 dynamic한 것이 되어야 한다. 즉 공과대학 전기공학과이 교과과정은 어떤 특정되고 고정된 기술 또는 설계에 대한 교과목으로 치우치는 것보다 수명이 길고 강력한 응용력과 창의력을 발휘하여 우리의 기술을 토착화하여 이를 우리의 것으로 만들 수 있는 것이 되어야 한다. 이러한 국내외적인 현실을 고려하여 당학회에서는 1974년도 조사연구사업의 일환으로 교과과정조사회를 구성하여 국내의 여러대학의 전기공학과 교과과정편성에 다소의 도움을 주고저 일차적인 시안으로서 다음과 같은 특징을 갖는 교과과정을 작성하였다.{3}$N$_{4}$등의 산화물 및 질화물로 대표되는 분자성 비정질 물질로서 금지대는 2eV보다 큰 세종류로 크게 분류할 수 있다. 분류할 수 있다. 한다. 단 개개의 문제에 관한 구체적인 해석 또는 검토에 관하여는 다음 기회에 미루기로하고, 우선 여기서는 당면문제로서 대처하지 않으면 안될 자동주파수제어문제및 계통의 경제운용문제만에 한정하여, 이것을 우리나라의 현상과 관련시켜 개설하고, 이들의 자동화에 관한 기본적인 문제를 간단히 적어 보겠다. 가능하다. 제작완료된 ASIC은 기능시험을 완료했으며 실제 line-of-sight(LOS) 시스템 구현에 적용중이다. 시대를 살아 갈 회원들이다. '컨텐츠의 시대'가 개막되는 것이며, 신세기통신과 SK텔레콤은 선의의 경쟁 과 협력을 통해 이동인터넷 서비스의 컨텐츠를 개발해 나가게 될 것이다. 3배가 높았다. 효소 활성에 필수적인 물의 양에 따른 DIAION WA30의 라세미화 효율에 관하여 실험한 결과, 물의 양이 증가할수록 그 효율은 감소하였다. DIAION WA30을 라세미화 촉매로 사용하여 아이소옥탄 내에서 라세믹 나프록센 2,2,2-트리플로로에틸 씨오에스터의 효소적 DKR 반응을 수행해 보았다. 그 결과 DIAION WA30을 사용하지 않은 경우에 비해 반응 전환율과 생성물의 광학 순도는 급격히 향상되었다. 전통적 광학분할 반응의 최대 50%라는 전환율의 제한이 본 연구에서 찾은 DIAION WA30을 첨가함으로써 성공적으로 극복되었다. 또한 고체 염기촉매인 DIAION WA30의 사용은 라세미화 촉매의 회수 및 재사용이 가능하게 해준다.해준다

• Journal of the Korea Society of Computer and Information
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• v.15 no.3
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• pp.65-72
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• 2010

We propose the asymmetric 2.5Gbps/622Mbps PON(Passive Optical Network) in order to reduce the bandwith of filter at receiver with inverse RZ(Return to Zero) code coded downstream and NRZ(Non Return to Zero) upstream re-modulation. I theoretically analyze BER(Bit Error Rate) performance and the power sensitivity with the optimal threshold level by performing simulation with MATLAB according to the types of downstream data. The results have shown that the optimal threshold level at the optical receiver could be saturated at 0.33 as the optical received power increase more than -26dBm to keep $10^{-12}$ of BER to a minimum. Also the power sensitivity is more improved by about 3dB by fixing the threshold level at 0.33 than the conventional receiver. The proposed system can be a useful technology for optical access networks with asymmetric upstream and downstream data rates because the optical receiver can be used without controlling threshold levels and that does not require a light source in optical network unit (ONU) and its control circuits in the optical line termination (OLT).

• Journal of KIISE:Information Networking
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• v.35 no.4
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• pp.251-267
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• 2008

In this paper, we present a distributed topology control algorithm for constructing an optimized topology having a minimal search-time in unstructured peer-to-peer network. According to the proposed algorithm, each node selects the best nodes having higher hit-ratio than other nodes as many as the number being exponentially proportional to the hit-ratio of the node itself, and then it connects to them. The ensemble behavior of the proposed algorithm is very similar to the recrystrallizing phenomenon that is observed in nature. There is a partial order relationship among the hit-ratios of most nodes of constructed topology. Therefore once query message visits a node, it has a higher hit-ratio than the node that was visited last by the message. The query message even sent from freeloader can escape to the node having high hit-ratio by one hop forwarding, and it never revisits any freeloader again. Thus the search can be completed within a limited search time. We also propose the Chain-reactive search scheme using the constructed topology. Such a controlled multicasting reduces the query messages by 43 percent compared to that of the naive Gnutella using broadcasting, while it saves the search time by 94 percent. The search success rate of the proposed scheme is 99 percent.