• 전자공학회논문지A
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• 제33A권10호
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• pp.123-129
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• 1996

LDD structure is widely accepted in fabricating short channel MOSFETs due to reduced short channel effect originated form lower drain edge electric field. However, modeling of the LDD device is troublesome because the analysis methods of LDD region known are either too complicated or inaccurate. To solve the problem, this paper presents a nonlinear resistance model for the LDD region based on teh fact that the electron mobility changes with positive gate bias because accumulation layer of electrons is formed at the surface of the LDD region. To prove the usefulness of the model, single source/drain and LDD nMOSFETs were fabricated with 0.35$\mu$m CMOS technolgoy. For the fabricated devices we have measured I$_{ds}$-V$_{gs}$ characteristics and compare them to the modeling resutls. First of all, we calculated channel and LDD region mobility from I$_{ds}$-V$_{gs}$ characteristics of 1050$\AA$ sidewall, 5$\mu$m channel length LDD NMOSFET. Then we MOSFET and found good agreement with experiments. Next, we use calculated channel and LDD region mobility to model I$_{ds}$-V$_{gs}$ characteristics of LDD mMOSFET with 1400 and 1750$\AA$ sidewall and 5$\mu$m channel length and obtained good agreement with experiment. The single source/drain device characteristic modeling results indicates that the cahnnel mobility obtained form our model in LDD device is accurate. In the meantime, we found that the LDD region mobility is governed by phonon and surface roughness scattering from electric field dependence of the mobility. The proposed model is useful in device and circuit simulation because it can model LDD device successfully even though it is mathematically simple.

• 한국전자파학회논문지
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• 제15권10호
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• pp.931-937
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• 2004

본 논문은 주파수 선택적 레일레이 페이딩(Frequency selective Rayleigh fading) 환경 하에서 수신 신호들 간에 상관이 존재할 때, OFDM(Othogonal Frequency Division Multiplexing) 다중 안테나 시스템의 채널 용량을 연구하였다. 송, 수신안테나를 각각 두 개 사용하였을 때, 채널 용량을 상관 계수의 함수로 closed-form 형태로 유도하였고, 각 안테나 당 평균수신 신호 전력이 동일할 때와 동일하지 않을 때 채널 용량에 미치는 영향을 분석하였다. 분석 결과 수신 신호의 상관 계수가 증가할수록 채널 용량이 감소하였고, 수신 신호 상관 계수가 약 0.7보다 클 때 채널 용량은 급격히 감소하였다. 그리고 각 안테나 당 평균 수신 신호 전력이 동일할 때 채널 용량은 최대가 됨을 알 수 있었다.

• 상하수도학회지
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• 제26권4호
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• pp.503-512
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• 2012

In Yongwon channel, its natural flow of seawater is blocked by the construction of Busan New Port including the container berth. The channel was transformed into a narrow and long one, where it is possible that ships are only allowed to pass through the north-side channel of Gyeonmado located at the point of river mouth to Songjeongcheon. In addition, Yongwon channel is approximately 100 m wide on average and 3,600 m long, and has the highest slenderness ratio (length/width = 36). So it is considered that the changes in the terrain characteristics of Yongwon channel is likely to alter the circulation of sea water, thereby changing its water quality. In this study, the bottom sediment were collected from the 48 points of the Yongwon channel and the long-term leaching characteristics were analyzed. Thus, changes in sediment and water quality were analyzed through the sediment release test to investigate the degree of contamination. The sediment release from the inside region was higher than the outer region, which is due to the pollutant that comes form the downtown area. The results of this study can be used to predict the water quality in the future and prepare the economically optimized countermeasures to improve the water quality of Yongwon channel, Busan New Port.

• 한국콘텐츠학회논문지
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• 제11권10호
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• pp.93-107
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• 2011

우리나라의 경우 SO와 위성방송사업자는 직접사용채널을 운용할 수 있다. 그런데 직접사용채널을 어떠한 목적과 방식으로 운용할 것인지에 대해서는 방송법상 규정이 없다. 때문에 SO와 위성방송사업자는 직접 사용채널을 운용하지 않거나 운용하더라도 주로 수익채널로 활용하고 있는 실정이다. 이런 점에서 직접사용채널을 어떻게 운용하는 것이 바람직한가를 살펴보기 위하여 미국과 일본의 사례를 검토하였다. 미국의 경우 수익성 채널, 공동이용채널, 액세스 채널 등 다양한 성격으로 활용하고 있었다. 일본의 경우 지방자치 단체와 긴밀한 연계를 통해 지역소식과 이슈에 대한 여론을 형성하고, 지역행사를 안내하는 등 지역채널로 서의 성격이 강조되고 있었다. 우리나라의 경우 SO는 직접사용채널이 아닌 지역채널을 통해 일본과 유사한 성격의 지역채널을 운용하고 있고, 위성방송은 주로 자사의 수익을 목적으로 직접사용채널을 운용하고 있다. 이런 점에서 방송사업자의 자사 이익에 의해 운용하는 방식이 아니라 직접사용채널의 위상과 운용방안에 대한 심도깊은 논의를 통해 공익적 측면에서의 활용방안을 모색해야 할 것이다.

• Steel and Composite Structures
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• 제3권4호
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• pp.243-260
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• 2003

This paper reports on the development of a new composite slab system that uses a large- lipped steel channel and reinforced concrete. The advantages of this new system are that it serves as both a structural unit and an unsupported form and it has a secondary structural barrier function. A concrete pouring test was carried out for the large-lipped steel channel. Full-scale tests were carried out to assess the flexural strength-deformation characteristics and structural mechanics of the composite slab. The barrier mechanics of the steel channel concrete element (referred to as the SC subunit) of the composite slab are examined. The test results indicate that the new composite slab has excellent strength, ductility characteristics, and a structural barrier function in its SC subunit that is highly effective against severe loading.

• 한국방재학회:학술대회논문집
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• 한국방재학회 2007년도 정기총회 및 학술발표대회
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• pp.624-627
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• 2007

There are many channel confluences existing in natural river systems, where the hydraulics are very complex because of the interactive between tributary and main river The RMA-2 model Is applied in this paper to model the confluence between Uksu Chun subriver and Nam Chun main river. Based on three types of assumed confluence forms, the model resuits present the hydraulics at channel confluence can be divided into several zones including a zone of separation immediately downstream of the junction branch channel, a maximum and minimum velocity region at upstream and downstream in the confluent channel, and a shear plane developed between the two combing flows at downstream of confluent channel. And the different types of confluent forms performs a very high effect on drainability of tributary, so it is very necessary to design a reasonable confluent forms.

• Journal of Computing Science and Engineering
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• 제7권2호
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• pp.81-88
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• 2013

In cognitive radio or dynamic spectrum access networks, a rendezvous represents meeting two or more users on a common channel, and negotiating to establish data communication. The rendezvous problem is one of the most challenging tasks in cognitive radio ad hoc networks. Generally, this problem is simplified by using two well-known mechanisms: the first uses a predefined common control channel, while the second employs a channel hopping procedure. Yet, these two mechanisms form a life cycle, when they simplify the rendezvous problem in cognitive radio networks. The main purpose of this paper is to point out how and why this cycle forms.

• 한국전산유체공학회지
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• 제16권1호
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• pp.90-95
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• 2011

The Navier-Stokes equations are solved to study the flow characteristics of a micro viscous pump. The viscous micropump is consisted of a stationary disk with a spiral shaped channel and a rotating disk. A simple geometrical model for the tip clearance is proposed and validated by comparing computed flow rate with corresponding experimental data. Present numerical solutions show satisfactory agreement with the corresponding experimental data. The tip clearance effect is found to become significant as the rotational speed increases. As the pressure load increases, a reversed flow region is seen to form near the stationary disk. The height of the channel is shown to be optimized in terms of the flow rate for a given rotational speed and pressure load. The optimal height of the channel becomes small as the rotational speed decreases or the pressure load increases. The flow rate of the pump is found to be in proportion to the width of channel.

• 한국통신학회논문지
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• 제29권11A
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• pp.1237-1243
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• 2004

This paper presents and analyses the closed-form expression of the average bit error rate (BER) for an asynchronous direct-sequence code division multiple access (DS-CDMA) system with coherent binary phase shift keying (BPSK) modulation scheme using a maximal ratio combining (MRC) diversity over a Rician fading channel. In addition to the average BER, outage probability, and user capacity of system are estimated as performance measures. The results are general enough so that it includes Rayleigh fading and nonfading channel with zero and infinite Rician factor, respectively, as special cases. The effects of various channel models, processing gains, and diversity orders on the system performances are also considered for the typical multipath delay profiles characterized by Rician fading channel.

• IEIE Transactions on Smart Processing and Computing
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• 제3권4호
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• pp.240-245
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• 2014

How well the self-interference cancellation (SIC) technique performs is a primary issue in realizing an in-band full-duplex (FD) wireless communication system. One factor affecting its performance is channel estimation error on the self-interference channel. We propose a new analog SIC scheme which is robust to channel estimation error. It uses phase rotators in the radio frequency (RF) chain. We also derive closed-form equations for the residual self-interference of the proposed and the conventional schemes. The analytical and numerical results show that the residual self-interference under the proposed SIC scheme is less than that using the conventional scheme, even though channel estimation error is present.