• Title/Summary/Keyword: 실측실험

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Performance Analysis of OFDM Communication Systems Considering PDP of Mobile Channels (이동통신 채널의 PDP에 따른 OFDM 통신 시스템의 성능 분석)

  • Lee, Jong-Gil
    • Journal of the Korea Institute of Information and Communication Engineering
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    • v.9 no.6
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    • pp.1182-1188
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    • 2005
  • In this paper, various power delay profiles (PDP) are simulated to study the influence of the PDP shape on the bit error rate (BER) performance of Orthogonal Frequency Division Multiplexing (OFDM) communication systems. Assuming Rayleigh fading with 16-QAM modulation scheme, the simulation focuses on the investigation of the various shapes of the PDP which are often characterized by peaks, slope, attenuation and distance of an echo profile of waves. This yields information about the properties of the channel, and can be applied to decide the performance of the systems according to the channel.

A Measurement of Passengers' Walking Speed on Passenger Ship(II) (연안여객선 일반 승선자의 보행속도 실측(II) -비숙련 일반인을 대상으로 한 실험-)

  • Hwang, Kwang-Il;Son, Byeung-Hun;Na, Wook-Jung;Ahn, Chang-Hwan;Hong, Won-Hwa;Lee, Soo-Ho;Koo, Jae-Hyeok;Jeon, Byeong-Cheong
    • Proceedings of the Korean Society of Marine Engineers Conference
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    • 2012.06a
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    • pp.206-207
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    • 2012
  • We need to develop intelligent smart card made unskilled general public's to the shelter on Passenger Ship. prior to development, we have to study passenger of characteristic. so we researched about domestic unskilled general public's of walking speed in refuge situation.

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Entrance Surface Dose according to Dose Calculation : Head and Wrist (피폭선량 산출을 통한 피부입사선량 계산: 머리 및 손목을 중심으로)

  • Sung, Ho-Jin;Han, Jae-Bok;Song, Jong-Nam;Choi, Nam-Gil
    • Journal of radiological science and technology
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    • v.39 no.3
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    • pp.305-312
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    • 2016
  • This study were compared with the direct measurement and indirect dose methods through various dose calculation in head and wrist. And, the modified equation was proposed considering equipment type, setting conditions, tube voltage, inherent filter, added filter and its accompanied back scatter factor. As a result, it decreased the error of the direct measurement than the existing dose calculation. Accordingly, diagnostic radiography patient dose comparison would become easier and radiogrphic exposure control and evaluation will become more efficient. The study findings are expected to be useful in patients' effective dose rate evaluation and dose reduction.

A Case Study of Pier Scour Considering Soil Erodibility (지반의 침식특성을 이용한 교각세굴 사례 연구)

  • 곽기석;정문경;이주형;박재현
    • Journal of the Korean Geotechnical Society
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    • v.20 no.3
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    • pp.67-74
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    • 2004
  • A case study was performed to verify the applicability of existing formulae for predicting bridge scour in cases where its piers are founded in fine-grained soils. The object of study was the Kanghwa Choji Bridge area where the streambed consists of mainly clayey soil. Site investigation included: direct measurement of scour depths around piers using an ultrasonic probe; and collection of undisturbed soil samples which were later used to determine geotechnical properties and scour rate under different stream velocities. Scour depth prediction was made by employing several conventional methods and compared with the measured value. All methods, not taking soil's intrinsic property against erosion into consideration, overestimated scour depth by a factor of 3.6 to 6.5. On the other hand, the SRICOS method yielded a reasonably acceptable overestimation by a factor of 1.7.

Applicability of Existing Formulae for Composite Roughness (기존 복합 조도계수 산정식의 적용성)

  • Kim, Ji-Sung;Lee, Chan-Joo;Kim, Keuk-Soo;Kim, Won
    • Proceedings of the Korea Water Resources Association Conference
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    • 2010.05a
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    • pp.1084-1088
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    • 2010
  • 일반적으로 자연하천에서는 횡방향 흐름저항 요소가 매우 다를 수 있다. 이러한 하천은 흐름저항 요인에 따라 몇 개의 소단면으로 구분될 수 있으며, 1차원 해석을 위해서는 단면 전체를 대표하는 복합 조도계수(composite roughness coefficient)를 사용함으로써 수위 또는 평균유속의 계산이 가능해 진다. 복합 조도계수는 각 소단면의 면적(A), 윤변(P), 또는 동수반경(R)을 적절히 조합하여 각 소단면의 조도계수에 가중치를 부여하면서 계산되는데, 각 산정식들의 개발과정에 도입된 가정 조건에 따라 상이한 가중치를 부여하게 되며, 일부 산정식들에서는 횡방향으로 동일한 재료로 구성된 조건에서도 복합 조도계수 산정 결과는 하상재료에 의한 조도계수와 다른 값을 산정하게 된다. 본 연구에서는 13개의 기존 복합 조도계수 산정식을 이론적으로 검토하였고, 소규모 실내 수리실험자료로부터 실측 복합 조도계수와 계산된 값을 비교 분석하였으며, 소단면 분할방법에 의한 기존 산정식의 적용성을 분석하였다. 분석결과, 윤변을 가중치로 사용하는 경우는 실측 복합 조도계수 그리고 각 산정식에 의한 계산 복합 조도계수의 차이가 비교적 작게 나타났으나 각 산정식의 가정조건에 유의하여야 하는 것으로 나타났다. 한편 단면적 또는 윤변과 동수반경을 조합하여 가중치로 사용하는 경우는 방법별로 큰 차이를 보이는 것으로 분석되었고, 그 원인은 단면분할 방법에 기인하므로 이러한 방법을 적용할 경우에는 소단면 분할방법에 특히 주의하여야 함을 알 수 있다.

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An Experimental Study for Drainage Capacity Improvement of Waterway with Steep Slope (급경사 사면 도수로의 배수능력 개선을 위한 실험적 연구)

  • Kim, Jung Soo;Kim, Ju Hyung;Yoon, Sei Eui
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.33 no.6
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    • pp.2303-2315
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    • 2013
  • In general, the waterway was installed for drain water from steep slope and waterway cover was set up to prevent overflow and water separation at berm of waterway. In this study, hydraulic experiment was conducted to analyze the flow characteristics and enact standard design criteria of the waterway. Hydraulic experimental apparatus which can change the slope of waterway and the length of berm were installed to analyze of flow characteristics at the waterway. The slopes of waterway were $40^{\circ}$, $50^{\circ}$, $60^{\circ}$, and $70^{\circ}$ and the range of discharge were 1.0~5.6 ${\ell}/s$. The flow in berm was distinguished two types such as hydraulic jump and splash flow. These kinds of flows depended on the rates of discharge in waterway. When inlet discharge was below 1.1~2.0 ${\ell}/s$, the separation phenomenon of water was generated at upper and lower portion in berm by the splash flow. The scattering range of water particles and length of water separation was measured depending on the slope of waterway. The start point of scattering was about 20 cm(1.3B) from the place connected upper waterway with brem and the length of water separation was till 210 cm(3.5B) from the place connected lower waterway with brem. Therefore, the waterway cover needed to install from starting of berm to 1B and from the lower part of berm to 3.5B.

Characteristics of Load-Settlement Behaviour for Embeded Piles Using Load-Transfer Mechanism (하중전이기법을 이용한 매입말뚝의 하중-침하 거동특성)

  • Oh, Se Wook
    • Journal of the Korean GEO-environmental Society
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    • v.2 no.4
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    • pp.51-61
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    • 2001
  • A series of model tests and analyses by load transfer function were performed to study load-settlement behaviour with relative compaction ratio of soil and embeded depth of pile. In the model tests, embeded depth ratio(L/D) of pile were installed 15, 20, 25 and relative compaction of soil(RC) is 85%, 95% and then cement were injected at around perimeter of pile. For analysis of embedded pile, the paper were compared results of model tests with analysis results by Vijayvergiya model and Castelli model, Gwizdala model of elastic plasticity-perfect plastic model and then the fitness load transfer mechanism was proposed to predict load-settlement behaviour of embeded pile. The analysis results of predicted bearing capacity by load transfer function, ultimate bearing capacity of embeded pile were approached to measured value and behaviour of initial load-settlement curve were estimated that load transfer function by Castelli were similar to measured value. The result of axial load analysis of bored pile shows that skin friction estimated by load transfer mechanism is investigated more a little than that of measured values.

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A Study on Implementation of Transient Radiation Effects on Electronics(TREE) Assessment System (전자소자의 과도방사선피해 평가체계 구축 연구)

  • Lee, Nam-Ho;Hwang, Young-Gwan;Kim, Jong-Ryul;Jeong, Sang-Hun;Oh, Seung-Chan
    • Journal of the Korea Institute of Information and Communication Engineering
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    • v.16 no.10
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    • pp.2329-2334
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    • 2012
  • In this paper, we performed a study of damage assessment model development to analyze the initial nuclear pulse radiation damage to semiconductor devices for military weapon systems. At first we modeled(M) the nuclear pulse radiation and diode device, and simulated(S) the output characteristics of the device to the input. Then the manufactured diodes which had the same characteristics with the modeled one were irradiated to the similar pulsed type radiation and their output signals were measured simultaneously. Error between the M & S results and the measured values of the analysis was 22.9%. Through the error value we could confirm that the damage assessment model simulated the TREE effects with a quite accuracy.

A Two Dimensional in Bended Open Channel Flows (만곡수로에서 2차원 흐름해석)

  • Yoon, Sei Eui;Lee, Jong Tae;Lee, Won Hwan
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.6 no.1
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    • pp.87-94
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    • 1986
  • Under natural condition, many rivers had shallow and gently curved shape in plane. A two dimensional mathematical model of the flow was a very attractive one. The flow characteristics in bended open channels were analyzed. The mathematical model based on the mass and the momentum equation of the two-dimensional unsteady flow was developed by introducing finite difference method and the double sweep algorithm. For the purpose of the verification of this model, the modeling results were applied to the L.F.M flume and the I.I.H.R flume. The results had a good agreement with the experimental data of the flumes. The results could be more close to the experimental data by controlling Chezy Coefficients in order to reduce the effect of friction around side wall, and be studied the importance of the convective term. The water surface profile, the direction and scale of depth average mean velocity and the path of the thread of maximum velocity in bended open channels could be computed.

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A Study on the Navigation Signal Characteristics of China Beidou Satellite Navigation System (중국의 BeiDou 위성항법시스템의 항법신호 분석에 관한 연구)

  • Ko, Kwang-Soob;Choi, Chang-Mook
    • Journal of the Korea Institute of Information and Communication Engineering
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    • v.19 no.8
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    • pp.1951-1958
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    • 2015
  • The paper is focused on not only the system characteristics of BeiDou, China GNSS, but also the statistic analysis based on its real data received from the BeiDou's satellite navigation messages. The 6-7 satellites, which are more than minimum number of 4 satellites to obtain 3-D position, are available for receiving navigation signal in stable case. It was also verified that the available satellites are deviated to specific coordinate and their signals are still unstable. Only as long as the received signal with the high stability, the precision of the BeiDou navigation satellite navigation system was identified with 5m level in deviation. The Beidou system is expected to be rising as a darkhorse in the future of the global satellite navigation area.