• Title/Summary/Keyword: 오 계수

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The Implementation of 16-QAM and 49-QPR for Effective Frequency Bandwidth (효과적인 주파수 대역활용을 위한 16-QAM과 49-QPR 시스템의 실현)

  • 진연강;방성일;서형모;강홍구;장상건;김종수
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.14 no.6
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    • pp.713-728
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    • 1989
  • In this paper, 16-QAM and 49-QPR systems utilized the raised cosine filter instead of LPF with the rectangular frequency characteristics as limiting channel bandwidth are implemented to measure their performances and effects of ISI. With the use of the raised cosine filter, and increase in SNR immunity can be obtained for specified spectrally efficient applications. Examination of the measured results reveals that the bandwidthe efficiency of 49-QPR implement is improved by about 8% and 15% higher than those of 16-QAM implement with the raised cosine characteristics having roll-off factor, a=0.5 and a=1, respectively. Also, equations for eye diagrams and error probability of 49-QPR system with AWGN and ISI are derived to analyze its performance and compared with the case of 16-QAM system.

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A Study on Friction Behavior of Textured Surface in Unlubricated State (무윤활 상태에서 미세공이 가공된 표면의 마찰거동에 관한 연구)

  • Oh, Seok-Ju;Kim, Sung-Gi;Kim, Kyung-Woong
    • Tribology and Lubricants
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    • v.25 no.4
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    • pp.217-224
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    • 2009
  • In this study, friction tests were carried out in order to investigate the friction behavior of textured surface in unlubricated state using ball-on-disk type apparatus. Test specimens were SUJ2 bearing steel ball and SM45C steel disk. Square arrays of circular micro-dimples were created on the surface of disk specimen by Nd:YAG Laser. Friction tests were performed for the disk specimen with various micro-dimple parameters and was also conducted for the variation of normal loads and relative velocities. The results showed that fiction coefficient of textured surface was lower than that of non-textured surface and the deeper depth of micro-dimple was, the lower friction coefficient obtained at the same diameter of micro-dimple in unlubricated state. Area density of micro-dimple had an effect on the friction coefficient. It was also found that friction coefficient generally decreased with the increase of normal load and relative velocity.

A Comparative Analysis of the Bacterial Growth Kinetic Parameters for Various Biological Nutrient Removal Processes (각종 질소·인 제거공정에서 도출된 미생물 성장 동역학 계수 비교 분석)

  • Lim, Se-Ho;Ko, Kwang Baik;Oh, Young-Khee
    • Journal of Korean Society on Water Environment
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    • v.20 no.6
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    • pp.647-651
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    • 2004
  • In this study, some of bacterial growth kinetic parameters were delineated and evaluated for the biological nutrient removal processes such as the $A^2/O$, 4stage-BNR, Intermittent Cycle Extended Aeration System(ICEAS) and Intermittently Aerated Cylindrical Oxidation Ditch(IACOD) processes. $Y_H$ values for the ICEAS process ranged from 0.71 to 0.74, and were higher than those for the other processes. It seems to indicated that organic carbons uptaked by microorganism were more used up for cell synthesis rather than for energy components in the ICEAS process. $b_H$ for the ICEAS and IACOD processes were lower than those for $A^2/O$ and 4stage-BNR processes. The $\mu_{max{\cdot}A}$ for the ICEAS was higher than those for the other processes, which indicated that desirable operating conditions for nitrifying bacteria's growth were established.

A Study on the Coupled Shaft-torsional and Blade-bending Vibrations in the Flexible Rotor-coupling-blade System (유연체 로터-커플링-블레이드 시스템의 로터 축과 블레이드의 연성 진동에 관한 연구)

  • Oh, Byung-Young;Lee, Sun-Sook;Yoon, Hyungwon;Cha, Seog-Ju;Na, Sungsoo
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.15 no.9 s.102
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    • pp.1023-1029
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    • 2005
  • In this paper, a dynamic model for the rotor shaft-coupling-blade system was developed. The blades are attached to a disk and driven by an electric motor shaft which is flexible in torsion. We assumed that the shaft torsional flexibility was lumped in the flexible coupling which is usually adopted in rotor systems. The Lagrangian approach with the small deformation theory for both blade-bending and shaft-torsional deformations was employed for developing the equation of the motion. The Assumed Modes Method was used for estimating the blade transverse deflection. The numerical results highlight the effects of both structural damping of the system and the torsional stiffness of the flexible coupling to the dynamic response of the blade. The results showed strong coupling between the blade bending and shaft torsional vibrations in the form of inertial nonlinearity, stiffness hardening and softening.

A People Counting Technique for Video Surveillance and Monitoring(VSAM) Systems (비디오에 의한 감시 및 관측(VSAM) 시스템을 위한 사람의 계수기법)

  • Do, Yong-Tae
    • Journal of Sensor Science and Technology
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    • v.11 no.1
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    • pp.28-38
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    • 2002
  • People are important targets for video surveillance and monitoring(VSAM) but difficult to be analyzed. In this paper, a technique to count people in image sequences is dealt as a prerequisite procedure for automatic tracking and behaviour analysis. A group of people is divided at local minima of the line connecting the highest pixels on the binary image of the people extracted from the image taken by a stationary video camera. As the properties of the divided regions vary according to the relative positions of the people in a group, different states are assigned for the completely occluded, partially occluded, completed separated individual, and wrongly divided regions. By analyzing the transition of the states of divided regions, the number of people on the site monitored is estimated. The technique is checked in real experimental situations.

The Analysis on Energy Performance according to Characteristics of Glazing in High-rise Office Buildings (Glazing 특성에 따른 고층 오피스 건물의 에너지성능 분석)

  • Hwang, Woo-Jin;Kim, Kyo-Joon;Choi, Won-Ki
    • 한국태양에너지학회:학술대회논문집
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    • 2011.04a
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    • pp.156-161
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    • 2011
  • In case of newly constructed buildings, the construction type is almost Curtain-wall system or large window in building skin. However, these kind of buildings have problems with regulations on building energy efficiency. And national regulations on building energy efficiency limit only the V-factor of window(except infiltration), it is hard to predict energy consumption of Curtain-wall buildings which gain large solar energy in summer. In this study, the influence of LSG(Light to Solar Gain) on energy performance was theoretically analyzed with simulation. LSG is the value of VLT divide SHGC and represents the optical performance of the glass or glazing. The Window & Therm program developed in LBNL was used to analyze window systems and EnergyPlus was used to building energy. Cases of glazing are three types; single coated Low-e clear glazing, tripple coated Low-e clear glazing, tripple coated Low-e tinted glazing. The results of this study are follows; 1) The building energy consumption of Alt-l, 2, 3 were about 300, 253, $259kWh/m^2{\cdot}yr$ respectively. Therefore, improvement of LSG could save the energy up to 16%. 2) The saved energy could be converted 1 billion won as annual benefit of total energy costs 3) SHGC and LSG more influence on cooling energy than heating energy in office buildings.

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The Simulation and Characterization of Interdigital Capacitor for Microwave Applications (마이크로 웨이브 응용을 위한 Iterdigital 캐패시터의 시뮬레이션 및 특성분석)

  • Woo, Tae-Ho;Yoon, Sang-Oh;Koh, Jung-Hyuk
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2008.06a
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    • pp.353-353
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    • 2008
  • 트랜지스터 속도는 현저하게 향상되어지는 반면에 RFICs(RF integrated circuits)는 대용량화, 고속화, 고집적화, 소형화, 고 효율화 온칩(on-chip) 수동소자의 부재에 의해 발전을 이루지 못하였다. 즉, 최근 전자기기의 집적화, 초소형화 됨에 따라 실장 밀도를 높이기 위해 부품의 소형화가 강하게 요구되는 동시에 Radio Frequency(RF)에서 이용가능한 수동소자인 capacitor를 개발하고자 본 논문에서는 손가락 모양(interdigital configuration)을 갖는 RF capacitor를 Ansoft사의 HFSS를 이용하여 이상적인 S-parameter, 정전용랑(capacitance), 손실계수(loss tangent)를 도출하고자 한다. 680um의 $Al_2O_3$ 기판에 BST doped MgO을 30um, Chromium과 gold를 각각 5um로 증착시켰다. 핑거 개수 (n, number), 핑거 길이(1, length), 핑거 간격(g, gap), 핑거 너비(w, width)를 변화 시켜가면서 이상적인 결과 값에 가까운 모양 (interdigital configuration)을 얻을 수 있었다. 핑거 수 3 개 일 때 입력 값에 대하여 손실 없는 출력 값(투과값)을 갖는 $S_{21}$이 1.5GHz에서 6dB이하로 떨어졌으며 핑거 간격이 줄고 핑거 너비가 커지고 핑거길이가 커질수록 높은 캐패시턴스 값을 갖는 것을 확인 할 수 있었다.

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Water Quality Impact Assessment Due to Dredging in the Downstream of the Nakdong River (낙동강 하류부에서의 오니준설에 따른 수질영향 분석)

  • Cho, Hong-Je;Han, Kun-Yeun;Kim, Sang-Ho
    • Water for future
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    • v.29 no.3
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    • pp.177-186
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    • 1996
  • QUAL2E model was applied to assess the water quality variations due to dredging of the bottom deposit in the downstream of the Nakdong River. A variedflow analysis was performed for the reach of Namji to Nakdong Estuary to estimate the hydraulic parameters. BFGS (Broyden-Fletcher-Goldfarb-Shanno) method was applied to determine the optimum reaction parameters and model verrification was performed based on these. Water quality modeling of dredging effects for BOD and DO in the reach was performed under low and average flow conditions and alternatives. It revealed that dredging had significant effedcts on the improvement of water quality in the reach.

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3-D Analysis of Temperature Distribution in Transformers (변압기의 3차원 온도분포 해석)

  • 오연호;송기동;선종호
    • The Transactions of the Korean Institute of Electrical Engineers B
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    • v.52 no.9
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    • pp.434-441
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    • 2003
  • This paper deals with the temperature characteristics according to the cooling medium and the duct size in model transformers. For the analysis and the temperature-rise tests, two 400kVA model transformers have been manufactured. One has been filled with the alpha oil as the cooling medium and constructed the duct sizes of $3\textrm{mm}$ and $5\textrm{mm}$ in the low-voltage and high-voltage windings respectively. The other has been filled the beta oil and the duct sizes were $4\textrm{mm}$ and $6\textrm{mm}$. The temperature-rise tests have been performed by the back-to-back method and the load factor has been controlled the range of 90%∼130%. The temperature values have been measured by the thermocouple and from the sixteen points in each transformer. A commercial CFD program "FLUENT" has been used for the analysis of temperature distribution. The geometry of transformer has been modeled to 3-dimensional by using the hybrid calculation mesh including the radiator. And also, the natural convection velocity has been measured at the oil top position, and compared with the calculated results.

Development of the parameter maps of the Modified Bartlett-Lewis Retangular Pulse Model for Han River Basin of Korea (한강유역에 대한 Modified Bartlett-Lewis Rectangular Pulse 모형의 매개변수 지도 작성)

  • Kim, Dong-Kyun;Lee, Seung-Oh;Jung, Young-Hoon;Kim, Soo-Young
    • Proceedings of the Korea Water Resources Association Conference
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    • 2012.05a
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    • pp.456-456
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    • 2012
  • 한강유역에 위치한 247개의 강우계에서 관측된 강우 자료를 분석하여 Modified Bartlett-Lewis Retangular Pulse Model (MBLRPM)의 매개변수들을 산정하고, 이들의 지도를 작성한 후, 이들의 정확도 및 매개변수들의 시/공간적 변화 유형을 분석하였다. 이를 위한 첫번째 과정으로, 각 강우 게이지에 대해 MBLRPM의 매개변수에 사용되는 통계치 (각 달에 대한 1, 3, 12, 24시간 누적 수준에서의 평균, 분산, 자기 상관계수, 무강우 확률)들을 계산한다. 이 후, 격자화된 한강유역의 각 셀에 대하여 앞서 계산된 강우 통계치를 Ordinary Kriging 공간 보간법을 통하여 할당한다. 이 후, 각 셀에 할당된 강우 통계치를 사용하여 MBLRPM의 매개변수들을 산정하여 각 매개변수들의 지도를 각 달에 대하여 얻는다. 매개변수 지도를 사용하여 MBLRPM에 의해 생성된 강우 데이터들은 관측치의 통계치를 정확성있게 재현하였으며, 시/공간적 경향성을 분석한 결과, 강우세포의 지속기간과 관련된 매개 변수를 제외한 나머지 5개의 매개변수들은 확연한 공간적 경향성을 보인 한 편, 시간적 경향성은 잘 나타나지 않았다. 본 연구 결과는 매개변수 산정이 힘든 MBLRPM의 특성을 극복하게 해주어 가상 강우 생성을 용이하게 함으로써 강우에 영향을 받는 여러 종류의 연구 주제에 대해 불확실성 분석을 할 수 있게 한다는 점에서 의미를 가질 수 있다.

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