• Title/Summary/Keyword: 상대오차

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Design-Based Small Area Estimation for the Korean Economically Active Population Survey (시군구 실업자 총계 추정을 위한 설계기반 간접추정법)

  • 정연수;이계오;이우일
    • The Korean Journal of Applied Statistics
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    • v.16 no.1
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    • pp.1-14
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    • 2003
  • In this study, we suggest the method of small area estimation based on the Economically Active Population Survey (EAPS) data in producing unemployment statistics for the local self-government areas (LSGAs) within large areas. The small area estimators considered are design-based indirect estimators such as the synthetic and composite estimators. The jackknife mean square error was used as a measure of accuracy of such small area estimators. The total unemployed and jackknife mean square errors of the 10 LSGAs within the large area of ChoongBuk region are derived from the estimation procedure suggested in this study, using EAPS data of December 2000. The reliability of small area estimators was assessed using the relative bias values and relative root mean square errors of these estimators. We find that under the current Korean EAPS system, the composite estimator turns out to be much more stable than other estimators.

The Relative Height Error Analysis of Digital Elevation Model on South Korea to Determine the TargetVertical Accuracy of CAS500-4 (농림위성의 목표 수직기하 정확도 결정을 위한 남한 지역 수치표고모델 상대 오차 분석)

  • Baek, Won-Kyung;Yu, Jin-Woo;Yoon, Young-Woong;Jung, Hyung-Sup;Lim, Joongbin
    • Korean Journal of Remote Sensing
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    • v.37 no.5_1
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    • pp.1043-1059
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    • 2021
  • Forest and agricultural land are very important factors in the environmental ecosystem and securing food resources. Forest and agricultural land should be monitored regularly. CAS500-4 data are expected to be effectively used as a supplement of monitoring forest and agricultural land. Prior to the launch of the CAS500-4, the relative canopy height error analysis of the digital elevation model on South Korea was performed to determine the vertical target accuracy. Especially, by considering area of interest of the CAS500-4 (mountainous or agricultural area), it is conducted that vertical error analysis according to the slope and canopy. For Gongju, Jeju, and Samcheok, the average root mean squared differences were calculated compared to the drone LiDAR digitalsurface models, which were filmed in autumn and winter and the 5 m digital elevation model from the National Geographic Information Institute. As a result, the Shuttle radar topography mission digital elevation model showed a root mean squared differences of about 8.35, 8.19, and 7.49 m, respectively, while the Copernicus digital elevation model showed a root mean squared differences of about 5.65, 6.73, and 7.39 m, respectively. In addition, the root mean squared difference of shuttle radar topography mission digital elevation model and the Copernicus digital elevation model according to the slope angle were estimated on South Korea compared to the 5 m digital elevation model from the National Geographic Information Institute. At the slope angle of between 0° to 5°, root mean squared differences of the Shuttle radar topography mission digital elevation model and the Copernicus digital elevation model showed 3.62 and 2.52 m, respectively. On the other hands root mean squared differences of the Shuttle radar topography mission digital elevation model and the Copernicus digital elevation model respectively showed about 10.16 and 11.62 m at the slope angle of 35° or higher.

A Numerical Analysis of the Heat Flow Equation using the Finite Element Method (유한요소법을 이용한 열흐름 방정식의 수치해석)

  • 이은구;김태한;김철성;강성수;이동렬
    • Proceedings of the IEEK Conference
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    • 2001.06b
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    • pp.161-164
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    • 2001
  • 정상상태에서 소자 내부의 격자온도 분포를 해석할 수 있는 시뮬레이터를 제작하였다. Slotboom 변수를 사용하여 열흐름 방정식을 이산화하였다. 또한 격자온도 분포를 고려한 초기 해의 설정 방법을 제안하였다. 제안된 방법의 타당성을 검증하기 위하여 N/sup + P 정합 다이오드에 대해 모의실험을 수행하여 MEDICI의 결과와 비교하였다 순방향 전압-전류 특성은 MEDICI의 결과와 비교하여 7% 이내의 최대 상대오차를 보였고 전위 분포와 온도 분포는 각각 2%, 2% 이내의 최대 상대오차를 보였다. BANDIS에서는 수렴을 위해 평균 3.7회 이하의 행렬 연산이 필요하였으며, MEDICI에서는 평균 5.1회 이하의 행렬 연산이 필요하였다.

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간이 선박조종 시뮬레이터 개선에 관한 연구

  • Choe, Won-Jin;Jeon, Seung-Hwan
    • Proceedings of the Korean Institute of Navigation and Port Research Conference
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    • 2019.11a
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    • pp.257-258
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    • 2019
  • 이 연구는 기 개발한 간이 선박조종 시뮬레이터의 조종성능 개선에 관한 것이다. 선박조종 시뮬레이터에서 모델선박의 조종성 지수는 임의로 정하는 것이 아니라 가능한 모델대상선박의 실제 움직임과 동등하거나 유사하게 설정되어야 한다. 선행연구에서는 이미 발표된 대학교 실습선(한바다호)의 선박조종 실선데이터를 기반으로 모델선박의 조종성 지수를 도출하였으나, 타각이 10°를 초과할 경우 네 종류의 실선시험 결과와 평균 17.9%의 상대오차가 발생하였다. 이에, 타각 10°, 20° 및 35°에서의 한바다호 조종성 지수에 대해 에르미트 보간을 이용하여 3차 다항식을 산출하고, 이를 모델선박에 적용하였다. 그 결과 타각 35° 이내의 전 구간에서 조종성능의 상대오차가 평균 13.7%에서 11.6%로 약 2.1% 개선됨을 확인하였다.

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Determination of the Optimal Sediment Discharge Formula for Hyeongsan River Using GSTARS (GSTARS모형을 이용한 형산강의 최적 유사량공식 결정)

  • Ahn, Jung Min;Lyu, Siwan;Lee, Nam Joo
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.32 no.1B
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    • pp.1-7
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    • 2012
  • Quasi-two dimensional numerical model (GSTARS) was applied to determine the optimal sediment discharge formula for simulating the sedimentologic characteristics of Hyeongsan river. The field measurements have been conducted to obtain the data, such as sediment discharge, bed material, and channel geometry, for model calibration and verification. The sediment discharge formulas, which have been generally used, have been assessed according to the average error, relative error, RMSE, RRMSE, discrepancy ratio and Nash-Sutcliffe efficiency coefficient for bed changes along the thalweg. From the results, Laursen formula(1958) shows the best performance to simulate the long-term bed change of Hyeongsan river.

Application of Slope-area Discharge Estimation Method using Continuously Observed Water Level Data in a Gravel Bed River -Case Study of the Dal Cheon River- (자갈하천에서 연속적인 수위 자료를 이용한 경사면적법 유량 산정 -달천 사례연구-)

  • Lee, Chan-Joo;Kim, Ji-Sung;Kim, Chi-Young;Kim, Dong-Gu
    • Journal of Korea Water Resources Association
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    • v.41 no.5
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    • pp.503-515
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    • 2008
  • In this study we calculate discharge by slope-area method using continuously observed water level data and analyse the results. This study is performed in the Dalcheon river reach of 960 m length including riffles and a pool, which is located downstream of the Goesan Dam. Three values of roughness coefficient are applied to discharge calculation, which are established using bed material size analysis. Another roughness coefficient value obtained from the river improvement plan is also used. Calculated discharges by slope-area method are compared with dam discharges. Relative difference from dam discharges appears to be largely affected by roughness values and a value of 0.042 or more seems most suitable for the entire study reach. Smaller roughness value is suitable to the reach which has gentler water surface slope than mean channel slope of the entire study reach, while a larger value to steeper reach. In case roughness value is set considering overall slope of the channel, it is desirable to select the entire calculation reach including both gentler and steeper sub-reaches. Since relative difference becomes nearly constant at over 500 cms, in case that verification of applied roughness is conducted with other directly measured discharge, accuracy of measurement by slope-area method for larger discharge may be improved.

The Comparison of the Performance for LMS Algorithm Family Using Asymptotic Relative Efficiency (점근상대효율을 이용한 최소평균제곱 계열 적응여파기의 성능 비교)

  • Sohn, Won
    • Journal of the Institute of Electronics Engineers of Korea SP
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    • v.37 no.6
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    • pp.70-75
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    • 2000
  • This paper examines the performance of adaptive filtering algorithms in relation to the asymptotic relative efficiency (ARE) of estimators. The adaptive filtering algorithms are Hybrid II and modified zero forcing (MZF) algorithms. The Hybrid II and MZF algorithms are simplified forms of the LMS algorithm, which use the polarity of the input signal, and polarities of the error and input signals, respectively. The ARE of estimators for each algorithm is analyzed under the condition of the same convergence speed. Computer simulations for adaptive equalization are performed to check the validity of the theory. The explicit expressions for the ARE values of the Hybrid II and MZF algorithms are derived, and its results have similar values to the results of computer simulation. It also revealed that the ARE values depend on the correlation coefficients between input signal and error signal.

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Assessment of Positioning Accuracy based on Medium- and Long-range GPS L1 Relative Positioning using Regional Ionospheric Grid Model (중·장기선 GPS L1 상대측위에서 격자형 지역 전리층 모델 적용에 따른 측위 정확도 영향 평가)

  • Son, Eun-Seong;Won, Jihye;Park, Kwan-Dong
    • Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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    • v.30 no.5
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    • pp.459-466
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    • 2012
  • The ionospheric delay is the largest error source in GPS positioning after the SA effect has been turned off. The ionospheric error can be easily removed by using ionospheric-free combinations but it is only restricted for dual-frequency receivers. Therefore, in this study, the regional ionospheric grid model was developed for single-frequency receivers. The developed model was compared with GIM to validate its accuracy. As a result, it yielded RMSE of 3.8 TECU for 10 days. And L1 medium- and long-range relative positioning was performed to evaluate positioning accuracy improvements. The positioning accuracy was improved by 46.7% compared with that without any correction of ionosphere and troposphere and was improved by 14.5% compared with that only tropospheric correction.

Design-Based Properties of Least Square Estimators of Panel Regression Coefficients Based on Complex Panel Data (복합패널 데이터에 기초한 최소제곱 패널회귀추정량의 설계기반 성질)

  • Kim, Kyu-Seong
    • Communications for Statistical Applications and Methods
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    • v.17 no.4
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    • pp.515-525
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    • 2010
  • We investigated design-based properties of the ordinary least square estimator(OLSE) and the weighted least square estimator(WLSE) in a panel regression model. Given a complex data we derive the magnitude of the design-based bias of two estimators and show that the bias of WLSE is smaller than that of OLSE. We also conducted a simulation study using Korean welfare panel data in order to compare design-based properties of two estimators numerically. In the study we found the followings. First, the relative bias of OLSE is nearly two times larger than that of WLSE and the bias ratio of OLSE is greater than that of WLSE. Also the relative bias of OLSE remains steady but that of WLSE becomes smaller as the sample size increases. Next, both the variance and mean square error(MSE) of two estimators decrease when the sample size increases. Also there is a tendency that the proportion of squared bias in MSE of OLSE increases as the sample size increase, but that of WLSE decreases. Finally, the variance of OLSE is smaller than that of WLSE in almost all cases and the MSE of OLSE is smaller in many cases. However, the number of cases of larger MSE of OLSE increases when the sample size increases.