• Proceedings of the IEEK Conference
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• 2002.07c
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• pp.1428-1431
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• 2002

It is general opinion that the future mobile multimedia networks will use different standards and a prospective solution to this problem will be software defined radio (SDR) techniques. SDR provides the flexibility to support multiple air interfaces and signal processing functions at the same time. Especially, digital signal processors and FPGAs are widely used for implementation of these adaptive and flexible functions of a baseband modem for SDR applications. Also, it is known that the modulation schemes of OCQPSK (Orthogonal Complex QPSK) and HPSK (Hybrid PSK) are used for IMT-2000 services of cdma2000 and WCDMA, respectively. Thus, in this paper, we design and implement an OCQPSK / HPSK modem using a DSP chip of Texas Instrument's TMS320C6701. One modulation scheme is operated by adaptive selection between the two schemes and 5 physical traffic channels differentiated by orthogonal codes are implemented in one DSP chip and each channel has 1Mbps data rates and 8Mcps chip rates.

• Proceedings of the KSME Conference
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• 2004.04a
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• pp.1114-1119
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• 2004

In a foaming process of microcellular plastics (MCPs) with a injection molding, research on the viscosity change that occurs when the gas is injected to the polymer has received little attention despite its importance. The purpose of this paper is to provide the basic data required to determine the processing condition by measuring viscosity changes against the gas injection rates of the blowing agent, and to verify the influence of the viscosity change on the flow condition of polymer inside the mold at the injection process.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 1998.05a
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• pp.155-158
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• 1998

차세대 이동통신 서비스는 영상을 포함한 멀티미디어 서비스나 고속 데이터통신 서비스가 가능해야한다. 본 논문에서는 W-CDMA 방식을 이용한 IMT-2000 단말기의 주파수 합성기를 포함하는 송신부를 설계한다. 요구되는 성능은 채널간격 10MHz, 변ㆍ복조 방식은 QPSK, 데이터 전송속도는 4.096Mcps, 주파수 합성기는 19.2MHz의 기준 주파수로 2,200∼2,300MHz 및 140MHz/260MHz의 주파수를 만든다. 구현된 주파수 합성기 및 송신부가 IMT-2000단말기의 요구 성능을 만족함을 보이고, W-CDMA를 이용한 WLL, Wireless LAN등 다양한 무선장비에 이용될 것으로 기대된다.

• Proceedings of the Korean Society For Composite Materials Conference
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• 2001.10a
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• pp.121-124
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• 2001

Surface-modified silica holds considerable promise in the development of advanced materials for good mechanical properties and stability. In this work, the surface and mechanical interfacial properties of silicas treated with silane coupling agents, such as Y-methacryloxy propyl trimethoxy silane (MPS). Y-glycidoxy propyl trimethoxy silane (GPS), and Y-mercapto propyl trimethoxy silane (MCPS), are investigated. The effect of silane surface treatments of silica on the surface properties and surface energetics are studied in terms of surface functional values and contact angle measurements. And their mechanical interfacial properties of the silica/rubber composites are studied by the composite tearing energy ($G_{IIIC}$). As a result. the mechanical interfacial properties are improved in the case of silane-treated composites compared with untreated one. It reveals that the functional groups on silica surface by silane surface treatments play an important role in improving the degree of adhesion at interfaces in a silica-filled rubber system.

• Journal of Computing Science and Engineering
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• v.10 no.3
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• pp.75-84
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• 2016

Medical cyber-physical systems (MCPS) integrate sensors, actuators, and software to improve patient safety and quality of healthcare. These systems introduce major challenges to safety analysis because the patient's physiology is complex, nonlinear, unobservable, and uncertain. To cope with the challenge that unidentified physiological parameters may exhibit short-term variances in certain clinical scenarios, we propose a novel run-time predictive safety monitoring technique that leverages a maximal model coupled with online training of a computational virtual subject (CVS) set. The proposed monitor predicts safety-critical events at run-time using only clinically available measurements. We apply the technique to a surgical glucose control case study. Evaluation on retrospective real clinical data shows that the algorithm achieves 96% sensitivity with a low average false alarm rate of 0.5 false alarm per surgery.

• Journal of Advanced Navigation Technology
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• v.2 no.2
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• pp.116-125
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• 1998

Most of modern mobile communication systems require low distortion in addition to high power and high efficiency characteristics for power amplifiers. The power amplifiers cause adjacent channel interference by intermodulation and spectral regrowth. In order to analyze the effects of the power amplifier on communication system, a 22Mcps spreaded digital modulated signal source and a ISM band power amplifier have been constructed, ACPR characteristics are simulated and measured for the RZ and NRZ encoded signals.

• The Journal of the Acoustical Society of Korea
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• v.15 no.5
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• pp.13-20
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• 1996

Recently, for implementation of neural networks extensive studies have been done especially VLSI technology has been regarded as the one of the most attractive means to implement neural networks. The main drawbacks of digital VLSI implementations are their large area and slow processing speed. In this paper to solve the speed and size problems we designed the efficient architecture using the binary convolution method for basic operation of neural cell, multiplication and addition. When it is used for implementing 3-layer network with 16 neural cell per layer that used neural cell based on binary convolution, clock of 50MHz and 26MCPS on 0.8${\mu}$ standard cell library has been achieved.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2006.05a
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• pp.421-422
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• 2006

According to the industrialization the using of polymers is increased by their mechanical or commercial demands. At now, the using of polymers is become bigger and bigger than yet. On the other words, our whole life is covered by the polymers. Due to the extended polymer using, the material cost is higher and higher. Therefore, the people used the polymer foaming process using the gas. The polymer foaming using the pentane or butane gas is prohibited by the government cause of the explosiveness and non-environmental friendly. Therefore, the members of MIT invented the Micro-cellular Polymer Foaming in 1980. The Micro-cellular Polymers has many cells in the polymer matrix. By compare between non-foamed polymers, the Micro-cellular Polymers have low material cost, soundproof and shock less. The purpose of this study is to study the twice foamed polymer by batch process. To know the reaction by step of microcellular foaming process, we measure the density of polymer. And to viewing the cell morphology, we used the scanning electron microscopy(SEM).

• ETRI Journal
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• v.34 no.2
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• pp.216-225
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• 2012

This paper presents a transceiver module for human body communications whereby a spread signal with a group of 64 Walsh codes is directly transferred through a human body at a chip rate of 32 Mcps. Frequency selective digital transmission moves the signal spectrum over 5 MHz without continuous frequency modulation and increases the immunity to induced interference by the processing gain. A simple receiver structure with no additional analog circuitry for the transmitter has been developed and has a sensitivity of 250 ${\mu}V_{pp}$. The high sensitivity of the receiver makes it possible to communicate between mobile devices using a human body as the transmission medium. It enables half-duplex communication of 2 Mbps within an operating range of up to 170 cm between the ultra-mobile PCs held between fingertips of each hand with a packet error rate of lower than $10^{-6}$. The transceiver module consumes 59 mA with a 3.3 V power supply.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.6 no.4
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• pp.3-38
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• 1996

The mobile station shall convolutionally encode the data transmitted on the reverse traffic channel and the access channel prior to interleaving. Code symbols output from the convolutional encoder are repeated before being interleaved except the 9600 bps data rate. All the symbols are then interleaved, 64-ary orthogonal modulation, direct-sequence spreading, quadrature spreading, baseband filtering and QPSK transmission. The sync, paging, and forward traffic channel except the pilot channel in the forward CDMA channel are convolutionally encoded, block interleaved, spread with Walsh function at a fixed chip rate of 1.2288 Mcps to provide orthogonal channelization among all code channels. Following the spreading operation, the I and Q impulses are applied to respective baseband filters. After that, these impulses shall be transmitted by QPSK. Authentication in the CDMA system is the process for confirming the identity of the mobile station by exchanging information between a mobile station and the base station. The authentication scheme is to generate a 18-bit hash code from the 152-bit message length appended with 24-bit or 40-bit padding. Several techniques are proposed for the authentication data computation in this paper. To protect sensitive subscriber information, it shall be required enciphering ceratin fields of selected traffic channel signaling messages. The message encryption can be accomplished in two ways, i.e., external encryption and internal encryption.