• 제목/요약/키워드: PCF

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IEEE 802.1 AVB 무선망에서의 프레임 전달 방법 (Frame Forwarding Method in IEEE 802.1 AVB Wireless Networks)

  • 김민준;전재현;권용식;김승호
    • 한국정보처리학회:학술대회논문집
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    • 한국정보처리학회 2009년도 추계학술발표대회
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    • pp.483-484
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    • 2009
  • IEEE 802.1 AVB는 LAN 상에서 동작하는 장치들의 시간을 동기화하고 저지연 스트리밍 서비스를 제공하기 위한 기술이다. 연구 중인 세부 표준 중에서도 IEEE 802.1Qav는 시간/손실에 민감한 스트림의 전달을 담당하는 표준이다. 현재 유선망에서의 프레임 전달 방법은 draft 버전 6에 이르러 거의 완성되어 가지만, 아직까지 무선망에 대한 표준은 정의되지 않고 있다. 따라서, 본 논문에서는 AVB 규격을 지원하는 무선망에서의 PCF 기반의 프레임 전달 방법을 제시한다.

THE OPPORTUNITIES AND CHALLENGES FOR CONTRACTUAL CONSIDERATION OF CONSTRUCTION-RELATED CARBON EMISSIONS FROM CIVIL INFRASTRUCTURE PROJECTS

  • Changbum Ahn;SangHyun Lee;Feniosky Pena-Mora
    • 국제학술발표논문집
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    • The 4th International Conference on Construction Engineering and Project Management Organized by the University of New South Wales
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    • pp.653-658
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    • 2011
  • Construction works of civil infrastructure projects generate a considerable amount of carbon emissions by utilizing a set of energy-intensive equipment and causing traffic congestion. However, the voluntary efforts of the contractor to mitigate these emissions are at an early stage. To address this issue, this paper explores the opportunities to take carbon emissions that would be caused from construction works into consideration in contracting methods and procedures. The opportunities for reducing carbon emissions from construction activities themselves are examined under the framework of Performance Contracting for Construction (PCfC), and carbon emissions from traffic congestion are attempted to be incorporated into the Road User Cost (RUC) calculation. This paper also identifies and discusses major challenges that must be confronted when considering the mitigation of these emissions in contracting methods and procedures.

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신생아기 급성 장염의 4종 바이러스 양성률 (Isolation rate of 4 type virus of acute gastroenteritis in full-term neonates during neonatal period)

  • 문수경;이재인;윤혜선;안영민
    • Clinical and Experimental Pediatrics
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    • 제50권9호
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    • pp.855-861
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    • 2007
  • 목 적 : 신생아기에 발생하는 급성 바이러스 장염의 원인중 가장 흔한 4종의 바이러스에 의한 장염의 임상적 특징, 증상, 양성률, 발생분포 등을 알아보고, 생활장소, 수유형태에 따른 차이점을 살펴보고자 하였다. 방 법 : 2004년 9월부터 2005년 8월까지 을지병원 소아과에 설사를 주증상으로 내원하여 급성 바이러스성 장염이 의심되어 입원하였던 이전에 건강했던 생후 4주 미만의 만삭 신생아 중에서 대변의 바이러스 검사가 가능했던 112명을 대상으로 하였다. 환아의 출생력, 임상적 특징, 임상 증상, 수유종류, 생활장소 등을 문진을 통해서 알아보고, 혈액검사, 소변검사, 방사선 검사, 대변에서 로타바이러스, 아스트로바이러스, 노로바이러스, 아데노바이러스 검사를 실시하였다. 결 과 : 112명의 입원 시 평균 나이는 $11.4{\pm}5.4$일, 평균 체중 감소는 $5.9{\pm}5.1%$, 평균 입원 기간은 $6.3{\pm}3.4$일이었고, 중등도 이상의 탈수는 51.7%, 대사성 산증을 동반한 경우는 13.4%였으며 입원 전까지 생활했던 장소는 조리원이 74.1%였고 수유 종류로는 혼합수유가 64.3%로 많았다. 대변에서 4종 바이러스 양성률은 33% 였고, 이중에서 로타바이러스가 59.5%, 아스트로바이러스가 29.7%, 노로바이러스가 10.8%를 차지하였고 아데노바이러스는 검출되지 않았다. 장소에 따른 바이러스 양성률에는 차이가 없었고, 두 곳 모두에서 로타바이러스가 주된 장염 바이러스로 확인되었고, 아스트로바이러스는 산후조리원에서, 노로바이러스는 집에서 각각 의미 있게 많이 검출되었다. 수유 종류에 따른 바이러스 양성률에는 차이가 없었다. 급성 장염의 발생분포는 대부분이 11월에서 12월에 집중되어서 발생하였고, 바이러스가 검출되었던 경우도 전체 분포와 유사한 양상을 보였다. 결 론 : 신생아시기에 바이러스 장염을 일으키는 흔한 4종의 바이러스 양성률은 33%였고, 이중 로타바이러스가 대부분을 차지하였으며, 생활장소나 수유형태에 따른 양성율의 차이는 보이지 않았고, 각 바이러스 간에 임상적 특징에도 차이가 없었다.

탄소시장과 탄소펀드 개발에 관한 연구 (A Study on the Carbon Market and Carbon Funds Development.)

  • 손우식;박명섭
    • 무역상무연구
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    • 제46권
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    • pp.265-313
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    • 2010
  • Kyoto Protocol is an international convention on concrete performance program for UNFCCC(United Nations Framework Convention on Climate Change), which regulate and prevent to global warming and officially came into effect on February 16, 2005. Kyoto flexible mechanisms, the agreed environmental system in March 1997 in the Third Conference of Parties in UNFCCC General Assembly, Emission Trading System(ETS), Clean Development Mechanism(CDM) and Joint Implementation(JI), are key policies related to environment. In advanced countries, greenhouse gas emissions should be reduced average 5.2% level compared to 1990 in total emissions during 2008-2012. World leading carbon market finished the trial on the EU ETS I greenhouse gas emissions trading system, EU ETS II is operated regularly after 2008. World Bank leads to make 'Prototype Carbon Fund(PCF)' in April 2004, which is the world first carbon fund and a representative public carbon fund type, World Bank operate various funds including present PCF. Thus, I would like to propose as follows in relation to this study: First, in the validity analysis of carbon funds, it would be needed to analyze the Emission Reduction Cost Efficiency(ERCE) of carbon. The ERCE is a break-even value which brings the Net Present Value(NPV) to zero. NPV approach is used among projects and it enables potential projects to be compared and evaluated the ERCE on the basis of the net present value of net future cash flows. Therefore, according to results of analysis, carbon funds should be developed and invested. Second, it would be necessary to allow of issuing bonds together with carbon funds, carbon finance etc. Third, carbon funds, it would be reasonable to have a relatively enough maturity in project and as a financial derivatives in the international financial markets, it is needed various types of transactions. Fourth, it would be needed to standardize the carbon emissions trading for more efficiently. Fifth, it would be necessary to establish and invest in various kinds of domestic and overseas global carbon funds, including governments, privates, governments and privates sectors. And it is also needed to establish the medium and long term plans for carbon funds. Sixth, it would be needed to foster the advanced trade mechanisms for carbon funds in the most effective ways. Finally, carbon funds should be used in harmony with international societies to reduce global warming as the social responsible investing funds and it should be contribute to sustainable development. In addition, it would seem that carbon funds should be studied on establishing the contributable standard of sustainable development in the future assignment.

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역삼투막 전처리로서의 2단 섬유상 여과기를 이용한 정수처리 연구 (Potable Water Treatment Study using the Double Stage Fiber Filter for the Pre-treatment of the Reverse Osmosis Membrane)

  • 배시열;장형욱;윤창한
    • 멤브레인
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    • 제20권2호
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    • pp.97-105
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    • 2010
  • 2009년 1월 3일부터 12월 1일까지 11개월간 공업용수를 주변지역에 공급하는 A정수장 응집침전조의 상등수를 대상으로 실험을 진행한 본 연구는 RO막 전처리 장치로서의 압력식 섬유여과기인 PCF 여과기 2대를 직렬연결한 공정의 적용 가능성을 평가한 것이다. 성능평가는 SDI (Silt Density Index)를 통해 간접적으로 RO막에 대한 전처리 성능을 평가하였다. 실험 기간 동안 PCF Filter로 유입된 원수의 탁도는 평균 0.79 (0.28~4.01) NTU이었으며, 처리수의 탁도는 평균 0.16(0.04~0.50) NTU로 탁도 제거효율은 평균 77%이었다. 일일 평균 처리유량은 약 230 $m^3$/day고 평균 역세유량은 8.7 $m^3$/day로 평균 역세수량은 3.8%로 나타났다. 여과수의 탁도 및 SDI 값은 측정 전 보관시간에 따라 증가하는데 이번 실험에서 몇몇 시료는 1~11일 동안 보관한 후 탁도 및 SDI가 측정되었으며, 이들 전체의 평균 SDI 값은 3.6 (2.26~5.00)으로 RO 제조업체에서 RO의 수명보증을 위해 통상 요구하는 SDI 값인 5.0 이하를 나타내었다. 따라서 RO 전처리공정의 SDI 측면에서 2단 섬유여과 공정이 적합함을 알 수 있었다.

인조골에서 식립 방법이 교정용 미니 임플란트의 기계적 안정성에 미치는 영향에 대한 예비연구 (The effects of different pilot-drilling methods on the mechanical stability of a mini-implant system at placement and removal: a preliminary study)

  • 조일식;추혜란;김성균;신윤섭;김덕수;김성훈;정규림;존황
    • 대한치과교정학회지
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    • 제41권5호
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    • pp.354-360
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    • 2011
  • Objective: To investigate the effects of different pilot-drilling methods on the biomechanical stability of self-tapping mini-implant systems at the time of placement in and removal from artificial bone blocks. Methods: Two types of artificial bone blocks (2-mm and 4-mm, 102-pounds per cubic foot [102-PCF] polyurethane foam layered over 100-mm, 40-PCF polyurethane foam) were custom-fabricated. Eight mini-implants were placed using the conventional motor-driven pilot-drilling method and another 8 mini-implants were placed using a novel manual pilot-drilling method (using a manual drill) within each of the 2-mm and 4-mm layered blocks. The maximum torque values at insertion and removal of the mini-implants were measured, and the total energy was calculated. The data were statistically analyzed using linear regression analysis. Results: The maximum insertion torque was similar regardless of block thickness or pilot-drilling method. Regardless of the pilot-drilling method, the maximum removal torque for the 4-mm block was statistically higher than that for the 2-mm block. For a given block, the total energy at both insertion and removal of the mini-implant for the manual pilot-drilling method were statistically higher than those for the motor-driven pilot-drilling method. Further, the total energies at removal for the 2-mm block was higher than that for the 4-mm block, but the energies at insertion were not influenced by the type of bone blocks. Conclusions: During the insertion and removal of mini-implants in artificial bone blocks, the effect of the manual pilot-drilling method on energy usage was similar to that of the conventional, motor-driven pilot-drilling method.

다차원 스펙트럼 해석법을 이용한 PDP TV의 저소음화 (Noise Reduction of PDP TV Using Multi-dimensional Spectral Analysis Method)

  • 양인형;정재은;곽형택;오재응
    • 한국소음진동공학회논문집
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    • 제21권1호
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    • pp.81-88
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    • 2011
  • The method is introduced for estimating the noise source contribution on the noise of PDP TV in a multiple-input system where the input sources may be coherent with each other. By the coherence function method, it is found that the biggest part of the noise source in the PDP TV noise is generated by the PCB boards which consume high power and produce high heat. This analysis is modeled as three-input/single-output system because the noise is generated by three main boards, X-board, Y-board, SMPS that are located close to each other. The coherence function method is proved to be useful tool for identifying of noise source. In this study, Transfer Path Analysis using MDSA is implemented to determine the quantitative noise contribution of each board for PDP TV with the rear case closed and with the rear case open. And the possibility of noise reduction is confirmed through the experimental method that isolates the most contributing board by adding sound-absorbing materials to it.

A Study on the Improvement of Membrane Separation and Optimal Coagulation by Using Effluent of Sewage Treatment Plant in Busan

  • Jung, Jin-Hee;Choi, Young-Ik;Han, Young-Rip
    • 한국환경과학회지
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    • 제22권10호
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    • pp.1353-1361
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    • 2013
  • The objectives of this paper are the characterization of the pretreatment of wastewater by microfiltration (MF) membranes for river maintenance and water recycling. This is done by investigation of the proper coagulation conditions, such as the types and doses of coagulants, mixing conditions (velocity gradients and mixing periods), pH, etc., using jar tests. The effluent water from a pore control fiber (PCF) filter located after the secondary clarifier at Kang-byeon Sewage Treatment Plant (K-STP) was used in these experiments. Two established coagulants, aluminum sulfate (Alum) and poly aluminum chloride (PAC), which are commonly used in sewage treatment plants to treat drinking water, were used in this research. The results indicate that the optimal coagulation velocity gradients (G) and agitation period (T) for both Alum and PAC were 200-250 $s^{-1}$ and 5 min respectively, but the coagulation efficiencies for both Alum and PAC were lower at low values of G and T. For a 60 min filtration period on the MF, the flux efficiencies ($J/J_0$ (%)) at the K-STP effluent that were coagulated by PAC and Alum were 92.9 % and 79.9 %, respectively, under the same coagulation conditions. It is concluded that an enhanced membrane process is possible by effective filtration of effluent at the K-STP using the coagulation-membrane separation process.

다차원 스펙트럼 해석법을 이용한 로드노이즈의 전달경로 해석 및 실내음압 예측 (Transfer Path Analysis and Interior Noise Estimation of the Road Noise Using Multi-Dimensional Spectral Analysis Method)

  • 박상길;강귀현;황성욱;오기석;노국희;오재응
    • 대한기계학회:학술대회논문집
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    • 대한기계학회 2008년도 추계학술대회A
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    • pp.779-784
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    • 2008
  • This paper presents a the method for estimating the noise source contribution on the road noise of the vehicle in a multiple input system where the input sources may be coherent with each other. By coherence function method, it is found that the biggest part of the noise source in the road noise is generated by structural vibration on the mechanical-acoustic transfer functions of vehicles. This analysis is modeled as four input/single output system because the noise is generated with four wheels that mechanism of the road noise is very complicated. The coherence function method is proved to be useful tool for identifying of noise source. The overall levels of the interior noise be coherence function method are compared with those measured and calculated by the frequency response function approach using mechanical excitation test. The experimental results have shown a good agreement with the results calculated by the coherence function method when the input sources are coherent strongly each other. The estimation of the road noise indicates that significant coherent can be achieved in the vehicle interior noise.

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무선랜에서의 실시간 및 비실시간 트래픽 스케줄링 (Scheduling of Real-time and Nonreal-time Traffics in IEEE 802.11 Wireless LAN)

  • Lee, Ju-Hee;Lee, Chae Y.
    • 한국경영과학회지
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    • 제28권2호
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    • pp.75-89
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    • 2003
  • Media Access Control (MAC) Protocol in IEEE 802.11 Wireless LAN standard supports two types of services, synchronous and asynchronous. Synchronous real-time traffic is served by Point Coordination Function (PCF) that implements polling access method. Asynchronous nonreal-time traffic is provided by Distributed Coordination Function (DCF) based on Carrier Sense Multiple Access with Collision Avoidance (CSMA/CA) protocol. Since real-time traffic is sensitive to delay, and nonreal-time traffic to error and throughput, proper traffic scheduling algorithm needs to be designed. But it is known that the standard IEEE 802.11 scheme is insufficient to serve real-time traffic. In this paper, real-time traffic scheduling and admission control algorithm is proposed. To satisfy the deadline violation probability of the real time traffic the downlink traffic is scheduled before the uplink by Earliest Due Date (EDD) rule. Admission of real-time connection is controlled to satisfy the minimum throughput of nonreal-time traffic which is estimated by exponential smoothing. Simulation is performed to have proper system capacity that satisfies the Quality of Service (QoS) requirement. Tradeoff between real-time and nonreal-time stations is demonstrated. The admission control and the EDD with downlink-first scheduling are illustrated to be effective for the real-time traffic in the wireless LAN.