• Journal of the Institute of Electronics Engineers of Korea TC
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• v.45 no.2
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• pp.6-12
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• 2008

In uplink cable modem link operated in time-division multiple access mode, it is crucial to employ a suitable preamble pattern enabling frame detection, coarse timing/carrier recovery. Preamble pattern based on the constant envelope zero autocorrelation sequence is proposed for the uplink cable modem compliant to the data over cable service interface specification. Frame detection, coarse/fine timing and carrier recovery algorithms suitable for the proposed preamble pattern are also proposed. We check up the performances using numerical results.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.12 no.3
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• pp.462-469
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• 2001

In this paper, local oscillator in K band using low frequency noise upconversion gain anaylsis was designed and measured. We extended Two Signal Method(TSM) to estimate upconversion gain and resulting phase noise. To confirm the validity of the proposed method, a free-running oscillator which had low upconversion gain was designed. The measured oscillation frequency was 23.42 GHz and phase noise at 1 MHz of offset was -105.2 dBc/Hz. Also, this oscillator was operated for subharmonic injection locked osci1lator(SILO). In this case, SILO showed ideal frequency multiplier phase noise characteristics at low subharmonic injection power level.

• KSBB Journal
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• v.6 no.4
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• pp.345-350
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• 1991

The purpose of this study is to investigate biomass characteristics and organic removal efficiency by changing superficial upflow velocity and organic loading rate in treating alcoholic distillery wastewater. Since the biomass concentration and the thickness of biofilm are very sensitive to superficial upflow velocity, a high concentration of biomass could be achieved by decreasing superficial upflow velocity that lowered the organic removal efficiency. Therefore, superficial upflow velocity should be controlled as to give optimum conditions and removal efficiency. Generally, activated sludge system shows 70% COD removal efficiency at$1.5kgCOD/m^3{\cdot}day$, but the fluidized-bed biofllm reactor shows 80% COD removal efficiency even at 6kgCOD/$m^2{\cdot}day$.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.48 no.5
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• pp.8-15
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• 2011

LTE-Advanced aims at peak data rates of 1Gbits/s for the downlink and 500 Mbits/s for the uplink, which can be accomplished only by using wide spectrum allocation of 100MHz as well as advanced multiple input multiple output antenna techniques to the uplink. This paper analyzes the uplink precoding techniques which include LTE codebook of downlink, singular value decomposition codebook, and equal gain transmission codebook over LTE defined single carrier frequency division multiplexing systems. Finally considering nonlinear transmit power amplifier model, it is shown that link-level performance of EGT is superior to those of any other precoding schemes.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.28 no.4B
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• pp.257-269
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• 2003

S(Synchrous)-DMT(Discrete Multi Tone) is an emerging cable modem technology applicable to the upstream channel for high speed multimedia communication. In this paper we analyze the transmitting and receiving process of S-DMT scheme and derive bit error probability of S-DMT scheme in the $\varepsilon$-mixture impulse noise model which appropriately reflects impulse noise model which approproately reflects impulse noise characteristics of upstream channel. The analysis results show a good match with the simulation results. We also compare Eb/No gain performance of S-DMT with TDMA in 16-, 32-, 64-QAM.

• Journal of Energy Engineering
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• v.24 no.1
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• pp.58-68
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• 2015

A marginal abatement cost analysis has been conducted to analyze the effects of abatement measures on greenhouse gas (GHG) emissions for the Korean residential sector. A bottom-up model using MESSAGE has been developed by defining the energy demand and constructing the reference energy system for the residential sector. A great amount of activity data has also been analyzed. Abatement potentials and related costs of individual abatement measures are investigated. The result from the marginal abatement cost analysis may provide general guidelines and procedures for the establishment of GHG abatement polices.

• Proceedings of the Korea Water Resources Association Conference
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• 2012.05a
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• pp.644-648
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• 2012

하천 내 설치하는 수제는 제방보호 및 유로변경의 목적으로 하천내 시공되는 구조물 중의 하나로서 하천복원과정에 있어 필수불가결한 구조물 중의 하나로 인식되고 있다. 수제는 대개 하나 이상의 일련의 군집형태로 수로 자체의 특성을 고려하여 설치가 되고 있다. 그러나 이러한 수제의 무분별한 설치는 주변 경관을 저해하거나 시공에 따른 비용 부담을 가중시키기 충분하다. 치수적 목적 이외에 경제적인 문제점을 해결하기 위해서는 실험을 통해 수제의 적절한 간격을 제시하는 것이 필요하다. 수제간격을 제시하기 위한 기초자료를 얻기 위해 본 연구에서는 기존 연직 및 하향군수제 하상변동실험과 동일한 조건으로 상향수제($\theta=45^{\circ}$)를 대상으로 수제간격에 대한 이동상 실험을 수행 하여 수제주변 및 수제역 내에서 발생하는 하상변동특성을 검토하였으며, 기존자료와 비교하였다. 실험결과 흐름집중 증가로 인해 국부세굴이 크게 발생하고 있으며 세굴폭은 수제길이의 3배 지점까지 영향을 미치고 있었으며, 퇴적고는 설치간격이 증가할수록 높게 형성되고 있었다. 연직 및 하향수제자료와 비교한 결과 상향수제는 수제끝단부에서 발생하는 국부적인 세굴에는 불리하나 수제역내 퇴적에는 유리한 것으로 나타났다.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.45 no.6
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• pp.1-9
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• 2008

This paper presents transmission parameters of DH(Dog-Horse) systems based on IEEE802.16e(WiBro) systems. DH requires higher uplink multimedia data rate, which is different from commercial WiBro systems. This paper designes some transmission parameters satisfying the DH system requirements and demonstrates link performance evaluation based on the parameters. For the transmission parameters, the number dwon/up link OFDM symbols are determined by 6/30, respectively. For reliable transmission of control signals, downlink modulation and coding rate are selected by QPSK, 1/2 coding rate and that of uplink is chosen by 16QAM 1/2 and 3/4 coding rate. Based on these parameters, computer simulations demonstrate the system performance of DH system.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.24 no.7B
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• pp.1252-1260
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• 1999

The HFC network has a architecture of a star topology in fiber optic trunks, and tree and branch topology is used in the part of coaxial cable. It is well known that the HFC upstream channel is noisy. Ingress, common mode distortion and impulse noise exist in the upstream channel. In order to provide Quality of Service(QoS) to users with real-time data such as voice, video and interactive services, the evolving IEEE 802.14 standard for HFC networks must include an effective priority scheme. The scheme separates and resolves collisions between stations in a priority order. It is important to simulate protocols under a practical environment. The proposed algorithm in this paper is simulated with the assumption that the collision detector made certain mistake due to noises. Simulation results show that the proposed algorithm is more efficient than existing tree-based algorithm under practical environment.

• Journal of Energy Engineering
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• v.25 no.3
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• pp.114-129
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• 2016

Since the release of mid-term domestic GHG goals until 2020, in 2009, some various GHG reduction policies have been proposed to reduce the emission rate about 30% compared to BAU scenario. There are two types of modeling approaches for identifying options required to meet greenhouse gas (GHG) abatement targets and assessing their economic impacts: top-down and bottom-up models. Examples of the bottom-up optimization models include MARKAL, MESSAGE, LEAP, and AIM, all of which are developed based on linear programming (LP) with a few differences in user interface and database utilization. The bottom-up model for electric sector requires demand management, regeneration energy mix, fuel conversation, etc., thus it has a very complex aspect to estimate some various policies. In this paper, we suggest a bottom-up BAU model for electric sector and how we can build it through step-by-step procedures such that includes load region, hydro-dam and pumping storage.