• Journal of the Korean Data and Information Science Society
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• 제17권4호
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• pp.1343-1348
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• 2006

Parametric estimation of a truncated point in a right truncated Rayleigh distribution will be considered. The MLE, a bias reduced estimator and the ordinary jackknife estimator of the truncated point in the right truncated Rayleigh distribution will be compared by mean square errors. And proposed estimators of the reliability in the right truncated Rayleigh distribution will be compared by their mean squared errors.

• 한국지반공학회논문집
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• 제35권6호
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• pp.17-26
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• 2019

이 연구에서는 쇄석말뚝공법의 한계상태설계법 적용을 위하여 양질의 현장재하시험 자료로부터 저항편향계수의 통계적 특성을 분석하고 지반 불확실성 및 시공 오차를 고려한 총 저항편향계수를 산정하였다. 저항편향계수 산정을 위한 예측모델은 기존 모델들에 비하여 높은 예측성능을 보인 Bong and Kim(2017)의 MLR 모형을 활용하였으며 그 적합성을 평가하였다. 저항편향계수의 확률분포를 산정하기 위하여 카이제곱 적합도 검정을 수행하였으며 정규분포가 가장 적합한 것으로 나타났다. 공칭저항의 총 변동성은 점토의 비배수전단강도 및 쇄석말뚝 시공 시 발생할 수 있는 시공 오차에 대한 불확실성을 포함하여 산정하였다. 최종적으로 총 저항편향계수의 확률분포는 로그정규분포를 따르는 것으로 나타났다. 총 저항편향계수의 변동성에 따른 확률분포의 매개변수는 Monte Carlo 시뮬레이션을 통하여 산정하였으며, 간편한 적용을 위하여 이에 대한 회귀식을 제안하였다.

• 한국컴퓨터그래픽스학회논문지
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• 제17권2호
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• pp.1-9
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• 2011

최근의 지형시각화 연구에서는 대용량 데이터를 실시간에 처리하기 위하여 여러 가지 상세단계조절 기법을 사용한다. 하지만 상세단계조절을 통한 메쉬 간략화 과정에서 발생하는 기하오차 때문에 연속된 프레임에서 기하파핑 현상이 열어난다. 본 논문에서는 거칠기맵과 편향맵을 이용하여 기하파핑 현상을 효과적으로 줄일 수 있는 방법을 제안한다. 거칠기맵과 편향맵은 지형 메쉬를 구성하는 정점이 적은 기하오차를 가지는 위치로 이동 시켜주는 역할을 한다. 거칠기맵과 편향맵은 텍스쳐로 저장되기 때문에 GPU에서 사용하기 적합하다. 또한 편향맵을 이용한 정점 이동 연산은 GPU에서 수행되므로 병렬처리를 통한 빠른 시각화가 가능하다.

• 한국측량학회지
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• 제32권1호
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• pp.1-8
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• 2014

The positions, attitudes, and internal orientation parameters of three line scanners are critical factors in order to acquire the accurate location of objects on the ground. Based on the assumption that positions and attitudes of the sensors are derived either from direct geo-referencing which of using Global Positioning Systems (GPS) and Inertial Navigation Systems (INS), or from indirect geo-referencing which of using Ground Control Points (GCPs), this paper describes on biased effects of Internal Orientation Parameter (IOP) on the ground. The research concentrated on geometrical explanations of effects from different focal length biases on the ground. The Synthetic data was collected by reasonable flight trajectories and attitudes of three line scanners. The result of experiments demonstrated that the focal length bias in case of indirect geo-referencing does not have critical influences on the quality of reconstructed ground space. Also, the relationships between IO parameters and EO parameters were found by the correlation analysis. In fact, the focal length bias in case of the direct geo-referencing caused significant errors on coordinates of reconstructed objects. The RMSE values along the vertical direction and the amount of focal length bias turned out to be almost perfect linear relationship.

• 대기
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• 제25권2호
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• pp.375-387
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• 2015

A Selected Multi-model CONsensus (SMCON) technique was developed and verified for the tropical cyclone track forecast in the western North Pacific. The SMCON forecasts were produced by averaging numerical model forecasts showing low 70% latest 6 h prediction errors among 21 models. In the homogeneous comparison for 54 tropical cyclones in 2013 and 2014, the SMCON improvement rate was higher than the other forecasts such as the Non-Selected Multi-model CONsensus (NSMCON) and other numerical models (i.e., GDAPS, GEPS, GFS, HWRF, ECMWF, ECMWF_H, ECMWF_EPS, JGSM, TEPS). However, the SMCON showed lower or similar improvement rate than a few forecasts including ECMWF_EPS forecasts at 96 h in 2013 and at 72 h in 2014 and the TEPS forecast at 120 h in 2013. Mean track errors of the SMCON for two year were smaller than the NSMCON and these differences were 0.4, 1.2, 5.9, 12.9, 8.2 km at 24-, 48-, 72-, 96-, 120-h respectively. The SMCON error distributions showed smaller central tendency than the NSMCON's except 72-, 96-h forecasts in 2013. Similarly, the density for smaller track errors of the SMCON was higher than the NSMCON's except at 72-, 96-h forecast in 2013 in the kernel density estimation analysis. In addition, the NSMCON has lager range of errors above the third quantile and larger standard deviation than the SMCON's at 72-, 96-h forecasts in 2013. Also, the SMCON showed smaller bias than ECMWF_H for the cross track bias. Thus, we concluded that the SMCON could provide more reliable information on the tropical cyclone track forecast by reflecting the real-time performance of the numerical models.

• 경영과정보연구
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• 제35권4호
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• pp.213-227
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• 2016

본 연구는 경영자의 능력이 자본시장에서의 정보비대칭 현상에 미치는 영향을 살펴보았다. 이를 위해, 2000년부터 2013년까지 유가증권 시장에 상장된 2,246개 기업-연도 표본을 대상으로 경영자의 능력이 정보비대칭 변수의 대용치인 재무분석가의 이익예측 정보에 어떠한 영향을 미치는지를 분석하였다. 분석을 위해, Demerjian et al. (2012)의 방법에 따라 DEA(Data Envelopment Analysis)를 이용하여 경영자의 능력을 측정하였고, 이렇게 측정된 경영자의 능력 변수와 재무분석가의 이익예측 오차(error) 및 편의(bias) 변수와의 관계를 분석하였다. 분석결과, 경영자의 능력이 뛰어날수록 재무분석가의 이익예측오차가 감소하였고, 재무분석가의 낙관적인 이익예측편의 또한 감소하는 것으로 나타났다. 본 연구는 경영자의 높은 능력으로 인한 회계정보의 질적 향상이 자본시장에서 정보비대칭 현상을 감소시켰음을 보여주었다는 점에서 공헌점을 가진다.

• 한국해양공학회:학술대회논문집
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• 한국해양공학회 2003년도 춘계학술대회 논문집
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• pp.141-148
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• 2003

This paper presents a rotating ann test for assessment of an underwater hybrid navigation system for a semi-autonomous underwater vehicle. The navigation system consists of an inertial measurement unit (IMU), an ultra-short baseline (USBL) acoustic navigation sensor and a doppler velocity log (DVL) accompanying a magnetic compass. The errors of inertial measurement units increase with time due to the bias errors of gyros and accelerometers. A navigational system model is derived to include the error model of the USBL acoustic navigation sensor and the scale effect and bias errors of the DVL, of which the state equation composed of the navigation states and sensor parameters is 25 in the order. The conventional extended Kalman filter was used to propagate the error covariance, update the measurement errors and correct the state equation when the measurements are available. The rotating ann tests are conducted in the Ocean Engineering Basin of KRISO, KORDI to generate circular motion in laboratory, where the USBL system was absent in the basin. The hybrid underwater navigation system shows good tracking performance against the circular planar motion. Additionally this paper checked the effects of the sampling ratio of the navigation system and the possibility of the dead reckoning with the DVL and the magnetic compass to estimate the position of the vehicle.

• 한국측량학회지
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• 제6권1호
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• pp.42-47
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• 1988

본 연구에서는 자유강 개념에 의한 수준망조정에 편의추정법을 적용하였으며 이때 편의계수에 따른 표고오차의 분포를 해석하므로써 최적의 편의계수를 결정하였다. 또한 1점고정 및 2점고정망조정과 비교 고찰하여 자유망조정기장의 유용성을 제시하는데 목적을 두고 있다.

• 지역연구
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• 제14권2호
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• pp.35-50
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• 1998

This paper examines the determinants of imbalanced regional development in Korea during the period of 1985-1995. The review of previous analytical techniques have been used to analyze the determinants of disparities in regional development of disparities in regional development, but few has applied the regression technique which reduces a bias due to heterogeneity across region. The results of the study show that Kmenta model with per capita GRDP as dependent variable can reduce the heterogeneity bias in regional development and can minimize the statical errors in estimation and interpretation of the coefficients of the explanatory variables. According to the results of Kmenta model, urban infrastructure such as roads, information and communication facilities are major causes of regional disparity over the period of 1985-1995. The results of the study also indicate that local government should devote their policy efforts to identify and utilize the unique soci-economic characteristics of each locality in the process of regional development.

• Journal of Communications and Networks
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• 제14권5호
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• pp.540-545
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• 2012

In this paper, the lagged cross-correlation of two probability density functions constructed by kernel density estimation is proposed, and by maximizing the proposed function, adaptive filtering algorithms for supervised and unsupervised training are also introduced. From the results of simulation for blind equalization applications in multipath channels with impulsive and slowly varying direct current (DC) bias noise, it is observed that Gaussian kernel of the proposed algorithm cuts out the large errors due to impulsive noise, and the output affected by the DC bias noise can be effectively controlled by the lag ${\tau}$ intrinsically embedded in the proposed function.