• Journal of Environmental Impact Assessment
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• v.20 no.5
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• pp.627-640
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• 2011

이 논문에서는 일사량과 일조시간에 관한 통상적인 선형관계식보다 정확한 비선형 관계식에 대한 적용검토를 수행한다. 일조시간을 이용한 일사량 추정에 이어서 Penman-Monteith 방정식을 이용하여 기준 증발산량을 추정하였다. 우리나라 20개 지점의 1997년부터 2006년까지의 일사량 및 일조시간 자료를 포함한 기상자료를 이용하여 선형 그리고 수정 비선형 Angstrom 방정식을 보정하고 기준 증발산량을 추정하였다. 일조시간과 일사량 사이의 선형과 비선형 관계식을 이용한 기준 증발산량의 상대비교를 수행하였다. 선형 및 비선형 관계식을 이용한 방법 모두 RMS 오차는 5.96, NSC(Nash-Sutcliffe Coefficient)는 0.95로 추정되었고, 그 차이는 매우 미미하였다. 그러나 상대적으로 일사량이 기준 증발산량에 크게 기여하는 하계에는 그 차이가 증가하기 때문에 보다 개선된 비선형 관계식을 이용하는 방법에 대한 엄밀한 검토가 필요하다.

• Journal of the Institute of Convergence Signal Processing
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• v.6 no.2
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• pp.95-99
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• 2005

This paper presents an accurate recovery method of the reference clock which is needed for network synchronization in two-way satellite multimedia systems compliant with DVB-RCS specification and which use closed loop method for burst synchronization. In these systems, the remote station transmits TDMA burst via return link. For burst synchronization, it obtains reference clock from program clock reference (PCR) defined by MPEG-2 system specification. The PCR is generated periodically at the hub system by sampling system clock which runs at 27MHz $\pm$ 30ppm. Since the reference clock is recovered by means of digital PLL(DPLL) using imprecise PCR values due to variable random jitter, the recovered clock frequency of remote station doesn't exactly match reference clock of hub station. We propose a robust recovery method of reference clock against random delay jitter The simulation results show that the recovery error is remarkably decreased from 5 clocks to 1 clock of 27MHz relative to the general DPLL recovery method.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.33 no.2
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• pp.83-94
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• 2015

Recently, the necessity of spatial data in unaccessible area was challenged to set up various plans and policies for preparing the unification and the cooperative projects between South-North Korea. Therefore, this paper planned to evaluate the possibility of adopting the error tolerance in Geometric correction for 1/5,000 digital topographic mapping, using the PLEIADES images and the TerraSAR GCPs (Ground Control Points). The geometric correction was performed by changing the number and placement of GCPs by GPS (Global Positioning System) surveying, as the optimal placement of 5 GCPs were selected considering the geometric stability and steady rate. The positional accuracy evaluated by the TerraSAR GCPs, which were selected by optimal placement of GCPs. The RMSE in control points were X=±0.64m, Y=±0.46m, Z=±0.28m. While the result of geometric correction for PLEIADES images confirmed that the RMSE in control points were X=±0.34m, Y=±0.27m, Z=±0.11m, the RMSE in check points were X=±0.50m, Y=±0.30m, Z=±0.66m. Through this study, we believe if spatial data can integrate with the PLEIADES images and the optimal TerraSAR GCPs, it will be able to obtain the high-precision spatial data for adopting the regulation of 1/5,000 digital topographic map, which adjusts the computation as well as the error bound.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.26 no.6
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• pp.405-412
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• 2014

A number of algal bloom models (red-tide models) have been developed and applied to simulate the redtide growth and decline patterns as the interest on the phytoplankton blooms has been continuously increased. The quantitative error analysis of the model is of great importance because the accurate prediction of the red-tide occurrence and transport pattern can be used to setup the effective mitigations and counter-measures on the coastal ecosystem, aquaculture and fisheries damages. The word "red-tide model" is widely used without any clear definitions and references. It makes the comparative evaluation of the ecological models difficult and confusable. It is highly required to do the performance test of the red-tide models based on the suitable classification and appropriate error analysis because model structures are different even though the same/similar words (e.g., red-tide, algal bloom, phytoplankton growth, ecological or ecosystem models) are used. Thus, the references on the model classification are suggested and the advantage and disadvantage of the models are also suggested. The processes and methods on the performance test (quantitative error analysis) are recommend to the practical use of the red-tide model in the coastal seas. It is suggested in each stage of the modeling procedures, such as verification, calibration, validation, and application steps. These suggested references and methods can be attributed to the effective/efficient marine policy decision and the coastal ecosystem management plan setup considering the red-tide and/or ecological models uncertainty.

• Proceedings of the KIEE Conference
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• 2011.07a
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• pp.1621-1623
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• 2011

발전소 수명연장의 필요성과 더불어 발전기 수명예측기법이 발전기 제작사를 중심으로 연구되어 왔으며 국내에도 수명예측과 관련기술들이 주로 일본의 영향을 받아 도입되어 발전소 현장에 활용되고 있고 평가의 신뢰성을 높이기 위해 노력하고 있다. 본 연구에서는 국내에 적용되고 있는 발전기 수명예측방법과 적용기준을 살펴보고 실제 발전소를 대상으로 수명평가한 사례중에서 평가결과의 신뢰성에 문제가 될 수 있는 몇가지 사례를 예시하고 분석하였다. 그 결과로 수명예측의 신뢰성을 높이기 위해서는 발전기의 냉각방식에 따라 수명평가 기준이 달리 적용되어야 한다는 것과, 최대부분방전량 측정오차를 줄여야 한다는 것, 고정자권선 단말부 흡습에 대한 고려가 필요하다는 것 등을 제시하였다.

• Proceedings of the Korea Water Resources Association Conference
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• 2008.05a
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• pp.1804-1808
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• 2008

최적유역관리 및 수질개선을 목표로 시행되고 있는 오염총량관리제도의 실질적인 효과를 달성하기 위해서는 해당 유역의 현황, 오염물질 배출특성 규명, 기준유량 및 기준수질의 산정이 요구되며, 하천 수리 수문 수질 모형화를 위한 장기간의 수질.유량 변동의 조사 및 분석이 선차적인 과제이다. 환경부는 오염총량관리제의 효율적인 추진을 위해 2004년 8월부터 현재까지 8일 간격(30회 이상/년)으로 오염총량관리 단위유역 41개 지점과 시도요구 6개 지점 등 총 47개의 지점에 대해 직 간접적으로 유량자료를 생성하고 있다. 이에 따라 관측한 수질 및 유량 자료는 단위유역별 오염부하량 산정, 삭감부하량 할당 및 이행평가에 활용하고 있는 상태이다. 또한 건설교통부, 수자원공사 등의 수문관측 기관에서는 도산, 낙동, 금호 등의 단위유역 지점에 대한 유량측정을 실시하여 주요 수자원계획시 기초자료로 활용하고 있다. 본 연구는 낙동강 유역의 기존 건설교통부, 수자원공사 관측망 측점지점에 대한 자료의 결측수 및 결측율, 수위-유량 관계곡선식 등의 정확도를 표준오차 및 불확실도를 정량적으로 산정하여 유량측정결과의 오염 총량과리를 위한 이용 가능성을 평가 및 소개하고자 한다.

• Proceedings of the Korean Nuclear Society Conference
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• 1995.05b
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• pp.883-888
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• 1995

본 연구에서 말단선량계에 대한 선량평가시 선량환산인자를 산출하기 위해 1995년의 ANSI N13.32 기준인 “말단선량계의 성능평가를 위한 기준”에서 제안된 기준 팬덤을 가지고 MCNP 전산코드를 이용하여 커마근사법에 의해 수행하였다. ANSI N13.32의 기준팬텀은 손·발 그리고 손가락을 대표하는 원통형으로서 특히 손·발 팬텀에 대해서는 뼈등가물질로 알루미늄을 삽입한 것을 제안함에 따라 본 계산 목적을 위하여 팬텀설계를 똑같이 모사하였으며 사용된 광자빔 에너지는 20keV에서부터 1.5MeV에 걸쳐 14개의 단일에너지를 선택하여 수행하였다. 본 연구에서 전산수행한 결과를 ANSI N13.32의 실험적 결과와 비교해 볼 때 50keV에서부터 1.5 MeV까지의 에너지 영역에서는 최대오차 6% 이내에서 거의 일치함을 보였다.

• The Korean Journal of Applied Statistics
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• v.30 no.5
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• pp.733-745
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• 2017

Local composite quantile regression is a useful non-parametric regression method widely used for its high efficiency. Data smoothing methods using kernel are typically used in the estimation process with performances that rely largely on the smoothing parameter rather than the kernel. However, $L_2$-norm is generally used as criterion to estimate the performance of the regression function. In addition, many studies have been conducted on the selection of smoothing parameters that minimize mean square error (MSE) or mean integrated square error (MISE). In this paper, we explored the optimality of selecting smoothing parameters that determine the performance of non-parametric regression models using local linear composite quantile regression. As evaluation criteria for the choice of smoothing parameter, we used mean absolute error (MAE) and mean integrated absolute error (MIAE), which have not been researched extensively due to mathematical difficulties. We proved the uniqueness of the optimal smoothing parameter based on MAE and MIAE. Furthermore, we compared the optimal smoothing parameter based on the proposed criteria (MAE and MIAE) with existing criteria (MSE and MISE). In this process, the properties of the proposed method were investigated through simulation studies in various situations.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.13 no.5
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• pp.11-20
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• 2014

Due to the importance of vehicle detector which plays an essential role in generating real-life traffic information, maintaining detector data quality is preeminent in advanced traffic management and information systems (ATMIS). To this end, agencies periodically conduct performance tests on detectors. Detector evaluation is generally performed by comparing baseline data with corresponding detector data. Here, two important things need to be addressed; one is errors (or uncertainties) included in baseline data and the other is the confidence interval concept to represent evaluation results of sample data to corresponding ones of population. To resolve these problems, a new detector evaluation scheme is introduced and the scheme is applied to individual level detector evaluations of loop, video image, and radar detectors. The purpose of individual level evaluation is to eliminate the balancing (or cancelling-out) effects of over- and under-counts. As a consequence, the proposed scheme is proven to be effectively applied to real-world detector evaluations.

• Journal of Radiation Protection and Research
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• v.31 no.1
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• pp.17-23
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• 2006

The purpose of this study is to provide the guidance necessary for making a selection of error distributions by analyzing influence of statistical distribution for a type of bioassay measurement error on the intake estimation. For this purpose, intakes were estimated using maximum likelihood method for cases that error distributions are normal and lognormal, and comparisons between two distributions for the estimated intakes were made. According to the results of this study, in case that measurement results for lung retention are somewhat greater than the limit of detection it appeared that distribution types have negligible influence on the results. Whereas in case of measurement results for the daily excretion rate, the results obtained from assumption of a lognormal distribution were 10 % higher than those obtained from assumption of a normal distribution. In view of these facts, in case where uncertainty component is governed by counting statistics it is considered that distribution type have no influence on intake estimation. Whereas in case where the others are predominant, it is concluded that it is clearly desirable to estimate the intake assuming a lognormal distribution.