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Algorithm for Scaling of the Decoder inputs with Variable Transmission Rate (가변 전송율을 갖는 디코더 입력의 스케일링을 위한 알고리듬)

  • 진익수;심재영
    • Journal of the Korea Institute of Information and Communication Engineering
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    • v.7 no.5
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    • pp.887-892
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    • 2003
  • In this paper, we propose a simple scaling algorithm for CDMA mobile communications where a voice traffic signals are transmitted by individual one of several data rates at every frames. The traditional method is based on using look-up table called SMT(symbol metric table), but the proposed algorithm is real-time direct scaling method through simple bit manipulations without lookup table. The bit error rate performance is calculated by computer simulation over AWGN and Rayleigh fading channels. From the results, it is shown that the proposed algorithm outperforms the traditional SMT method on Rayleigh channel by 0.3∼0.8dB, while achieving the less H/W complexity.

Tools for Light Curve of Exoplanet Transit Observation with Youth

  • Kang, Wonseok;Kim, Taewoo;Yoo, Jihyun;Kim, Jeong-eun;Kang, Min;Noh, Hannah
    • The Bulletin of The Korean Astronomical Society
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    • v.42 no.2
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    • pp.70.2-70.2
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    • 2017
  • Transit event of exoplanet is a good example of observational studies with youth, because the event is geometrically simple and its analysis is essential to astronomical observation. Therefore, we developed the package of data reduction and aperture photometry in Python for educational purpose. In 27 July, we observed the transit event of TrES-3b with the students of "NYSC Space Science Club" program, and presented the Python package, PyPhotW for data reduction and aperture photometry. PyPhotW consists of simple functions for youth to understand the processes easier. Nonetheless, the photometric results of PyPhotW show a good agreement with those of Source Extractor, ${\Delta}m{\sim}-0.01{\pm}0.03$ and $-0.04{\pm}0.08$ for TrES-3b and TrES-5b time-series observations in 27 - 28 July.

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Dispersity and Electro-Conductivity of PU Grafted MWCNT/PU Composite via Simple Blending Method (블렌딩을 이용한 폴리우레탄 그라프트 다중벽 탄소나노튜브/폴리우레탄 복합체의 전기 전도성 및 분산 특성)

  • Yun, Sung-Jin;Im, Hyun-Gu;Kim, Joo-Heon
    • Applied Chemistry for Engineering
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    • v.21 no.5
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    • pp.500-504
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    • 2010
  • The PU-g-MWNTs/PU film was synthesized by simple blending method to fabricate composites which have excellent mechanical and electrical properties. PU-g-MWNTs based composite revealed much enhanced dispersity than pristine MWNTs composite because of interfacial interaction related with interfacial compatibility between polymer matrix and PU on the MWNTs surface. The electro-conductivity of composite was measured as a function of PU-g-MWNTs concentration. The results were correlated with percolation threshold theory. As a result, the critical concentration and exponent of electro-conductivity behavior was equal to 0.78 wt% and 0.945.

The Unsteady 2-D Numerical Analysis in a Horizontal Pipe with Thermal Stratification Phenomena (열성층현상이 존재하는 수평배관내에서의 비정상 2차원 수치해석)

  • Youm, Hag-Ki;Park, Man-Heung;Kim, Sang-Nung
    • Nuclear Engineering and Technology
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    • v.28 no.1
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    • pp.27-35
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    • 1996
  • In this paper, an unsteady analytical model for the thermal stratification in the pressurizer surge line of PWR plant has been proposed to investigate the temperature profile, flow characteristics, and thermal stress in the pipe. In this model, the interface level, between hot and cold fluid, is assumed to be a function of time while the other models had developed for time independent or steady state. The dimensionless governing equations are solved by using a SIMPLE (Semi-Implicit Method for Pressure Linked Equations) algorithm. The analysis result for an example shows that the maximum dimensionless temperature difference is about 0.78 between hot and cold sections of pipe wall and the maximum thermal stress by thermal stratification is calculated about 276 MPa at the dimensionless time 27.0 under given conditions.

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Investigation of the effect of grain size on liquefaction potential of sands

  • Sonmezer, Yetis Bulent;Akyuz, Abdussamed;Kayabali, Kamil
    • Geomechanics and Engineering
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    • v.20 no.3
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    • pp.243-254
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    • 2020
  • Due to the permanent damage to structures during earthquakes, soil liquefaction is an important issue in geotechnical earthquake engineering that needs to be investigated. Typical examples of soil liquefaction have been observed in many earthquakes, particularly in Alaska, Niigata (1964), San Fernando (1971), Loma Prieta (1989), Kobe (1995) and Izmit (1999) earthquakes. In this study, liquefaction behavior of uniform sands of different grain sizes was investigated by using the energy-based method. For this purpose, a total of 36 deformation-controlled tests were conducted on water-saturated samples in undrained conditions by using the cyclic simple shear test method and considering the relative density, effective stress and mean grain size parameters that affect the cumulative liquefaction energy. The results showed that as the mean grain size decreases, the liquefaction potential of the sand increases. In addition, with increasing effective stress and relative density, the resistance of sand against liquefaction decreases. Multiple regression analysis was performed on the test results and separate correlations were proposed for the samples with mean grain size of 0.11-0.26 mm and for the ones with 0.45-0.85 mm. The recommended relationships were compared to the ones existing in the literature and compatible results were obtained.

A study on the sanitary condition of wells in a rural area, Korea. (일부 농촌지역의 정호에 대한 환경위생학적 조사연구)

  • 이성호;이선덕
    • Journal of Environmental Health Sciences
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    • v.3 no.1
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    • pp.48-52
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    • 1976
  • A study was carried out to investigate the sanitary condition of 107 wells in Jungil Ri, Kyunggi province and Daeso Ri, Choongbuck province, from July 1, to August 30, 1975. In this study, coliform groups were examined by the membrane filter method as well as general sanitary condition, pH value, ammonia nitrogen, hardness and water temperature. The following results were obtained: 1. Average value of general sanitary condition in the wells were 15$\circ$C in temperature, pH 6.4, hardness 124ppm and Cl ion 34ppm. 2. Coliform group was positive at all out of 30 open wells and 33 out of 45 pumped wells, while only 7 out of 32 tap water in the simple typed water supply system showed the evidence of coliform groups. 3. The positive rate of ammonia nitrogen revealed 13% out of 107 wells and that of nitrite nitrogen was 36.4% and 6 wells rate of 5.6% were ammonia nitrogen and nitrite nitrogen positive at same time. 4. Colflorin group positive of 32 tap water in the simple typed water supply system 3(27%) out of 11 samples with no residual chlorine, 3(17%) out of 17 with 0.1 to 0.5ppm, 1 out of 3 with 0.6 to 1.0 ppm and none out of 1 with 1.1 to 1.5 ppm.

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A study on establishing the aerodynamic database though the external flow method of a rotating vehicle (회전 운동하는 비행체의 외부 유동장 해석을 통한 공력데이터베이스 구축 연구)

  • Kang, Tae-Woo;Ahn, Jong-Moo;Lee, Hee-Rang;Choi, Jae-Ho
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.18 no.8
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    • pp.41-47
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    • 2017
  • With the introduction of new technologies, ground weapons have led to the development of artificial intelligence and the attention of major developed countries. In this study, CFD was performed through the BLU-103 model to obtain aerodynamic data for aircraft that are subjected to rotational motion. To simulate the steady-state of a rotating body, the body was fixed and the principle of rotating the body by rotating the surrounding air was used. In order to examine the aerodynamic feasibility of the rotating aircraft, the analysis was carried out at intervals of $30^{\circ}$ angle from $0^{\circ}$ to $90^{\circ}$ for the simple shape and the side slip angle. It was confirmed that the drag coefficient for the simple model satisfies the quantitative results of 1.0 ~ 1.2 through CD presented in "Drag Book". The aerodynamic data was constructed by applying the valid input verified through the simple type analysis conditions to the actual shape, and the tendency was analyzed. The analysis confirmed that CX, CZ and CY increase not only in the simple model but also in the rotation of the actual model. Especially, the influence of CZ was judged to have contributed to the flight.

COMMUTATIVE MONOID OF THE SET OF k-ISOMORPHISM CLASSES OF SIMPLE CLOSED k-SURFACES IN Z3

  • Han, Sang-Eon
    • Honam Mathematical Journal
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    • v.32 no.1
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    • pp.141-155
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    • 2010
  • In this paper we prove that with some hypothesis the set of k-isomorphism classes of simple closed k-surfaces in ${\mathbf{Z}}^3$ forms a commutative monoid with an operation derived from a digital connected sum, k ${\in}$ {18,26}. Besides, with some hypothesis the set of k-homotopy equivalence classes of closed k-surfaces in ${\mathbf{Z}}^3$ is also proved to be a commutative monoid with the above operation, k ${\in}$ {18,26}.

Effects of reflective index of fiber sensor coil end on current measurement (광CT 센서코일 끝단의 반사율이 전류측정에 미치는 영향)

  • Park, Hyoung-Jun;Kim, Hyun-Jin;Song, Min-Ho
    • Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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    • 2008.05a
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    • pp.74-77
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    • 2008
  • We improved an efficiency of fiber-optic current transformer by using a metal-coated sensor coil. To reduce the linear birefringence, we used a length of spun fiber as sensor coil, and then used a flint glass fiber coil for comparison. To make the sensor coil in the reflection type, we used different reflection mirrors at the end of the sensor coil, such as a Faraday rotator mirror, a simple mirror, a metal-coated fiber end and a simple fiber end. From the experimental results, the linear error of current measurements were less than ${\sim}$ 0.2 % regardless of the mirror types. The metal-coated sensor was the most cost-effective considering the fabrication cost and the simple structure.

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Statistical notes for clinical researchers: simple linear regression 2 - evaluation of regression line

  • Kim, Hae-Young
    • Restorative Dentistry and Endodontics
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    • v.43 no.3
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    • pp.34.1-34.5
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    • 2018
  • In the previous section, we established a simple linear regression line by finding the slope and intercept using the least square method as: ${\hat{Y}}=30.79+0.71X$. Finding the regression line was a mathematical procedure. After that we need to evaluate the usefulness or effectiveness of the regression line, whether the regression model helps explain the variability of the dependent variable. Also, statistical inference of the regression line is required to make a conclusion at the population level, because practically, we work with a sample, which is a small part of population. Basic assumption of sampling method is simple random sampling.