• The Korean Journal of Applied Statistics
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• v.26 no.3
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• pp.549-568
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• 2013

This paper discusses conversion methods between multiple decrement models and associated single decrement models. One of most popular assumptions on fractional age is UDD(uniform distribution of decrement) or constant force of mortality in actuarial practice. Instead of these assumptions, this paper suggests cubic spline interpolation to approximate the distribution of fractional age with the continuous force of decrements. Conversion formulas are derived. The comparisons of these two methods based on the numerical data show that the cubic spline interpolation approach is more accurate.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.14 no.1
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• pp.86-93
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• 2002

In this study, numerical experiments were performed to decide the proper size off finite element for the analysis of harbor resonance problems. Various sizes of finite elements were considered from 1/3 to 1/60 of wavelength to model a fully opened rectangular harbor. Through the numerical results, the proper number of finite elements per wavelength were revealed to be nine within two percents errors allowed in resonant period and amplification ratio, while twelve within one percent error. It was fecund that error rates of resonant periods decrease linearly, while those of amplification ratio decrease with oscillating form as the size of an element decreases. The error of amplification ratio increases more rapidly than that of resonant period in case of element numbers below nine.

• 제어로봇시스템학회:학술대회논문집
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• 1996.10b
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• pp.796-799
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• 1996

광섬유는 코어(Core), 클레드(Clad), 그리고 1,2차 코팅(Coating)으로 구성되어 있다. 본 연구에서는 광섬유의 코팅에 생기는 결함의 유무 및 종류와 크기를 분류하는 Vision System을 구현하였다. 전처리 과정으로, CCD Camera를 이용하여 얻은 화상에 대하여 Sobel 연산자로 경계선을 추출하고, 문턱값(Threshold Value)을 적용하여 이진 화상을 만든다. 외경 정보 추출을 위하여, 투영 정보, 수리 형태학(Mathematical Morphology)적 연산을 수행하고, 결함의 종류와 크기를 효율적으로 분류하도록 Tree Classifier를 설계하였다. 실험 결과로서 각 결함 별 오차율, 전체 오차율(Total Error Rate)등을 제시하였다.

• Proceedings of the Korean Institute of Intelligent Systems Conference
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• 1998.10a
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• pp.166-172
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• 1998

PD 제어기는 산업현장에 가장 널리 운영되는 제어알고리즘이지만 지금까지 보편적으로 사용되고 있는 PID 파라메터 동조방법인 Ziegler-Nichols 동조법으로는 화학공정 같은 비선형 특성이 크거나, 시정수가 큰 플래트에서는 좋은 성능을 얻을 수 없다. 본 논문에서는 릴레이 동조 실험을 통하여 임계 이득과 발진주기를 구하고, 이 값들로부터 Z-N 동조법을 적용하여 초기 동조값을 구한다. 이 값에 의해서 얻어진 공정 출력의 오차와 오차변화율을 입력으로 한 퍼지 동조기를 통하여 PID 제어기의 비례이득과 적분시간을 구하는 동조 방법을 제시한다.

• Journal of Korean Society of Transportation
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• v.26 no.4
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• pp.123-133
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• 2008

Information collection systems and applications in a ubiquitous environment has emerged as a leading issue in transportation and logistics. A productive application example is a traffic information collection system based on probe vehicles and wireless communication technology. Estimation of hourly OD pairs using probe OD data is a possible target. Since probe OD data consists of sample OD pairs, which vary over time and space, computation of sample rates of OD pairs and expansion of sample OD pairs into static OD pairs is required. In this paper, the authors proposed a method to estimate sample OD data with probe data in Jeju City and expand those into static OD data. Mean absolute percentage difference (MAPD) error between observed traffic volume and assigned traffic volume was about 22.9%. After removing abnormal data, MAPD error improved to 17.6%. Development of static OD estimation methods using probe vehicle data in a real environment is considered the main contribution of this paper.

• Journal of Astronomy and Space Sciences
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• v.15 no.1
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• pp.119-138
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• 1998

Recently measurements of atmospheric trace gases from satellite are vigorous. So the development of its data processing algorithm is important. In this study, retrievalof vertical ozone profile from the atmospheric transmittance measured by satellite solar occultation method and its sensitivity to temperature and pressure are investigated. The measured transmittance from satellite is assumed to be given by the limb path transmittance simulated using annual averaged Umkehr data for Seoul. The limb path transmittance between wavelengths $9.89{\mu}m$ and $10.2{\mu}m$ is simulated with respect to tangent heights using the ozone data of HALOE SIDS(Hallogen Occultation Experiment Simulated Instrument Data Set) as an initial profile. Other input data such as pressure and temperature are also from HALOE SIDS. Vertical ozone profile is correctly retrieved from the measured transmittance by onion-peeling method from 50km to 11km tangent heights with the vertical resolution of 3km. The bias error of $\pm0.001$ in measured transmittance, the forced error of $\pm3K$ in each layer temperature, and the forced $\pm3%$ error in each layer pressure are assumed for sensitivity tests. These errors are based on the ADEOS/ILAS error limitation. The error in ozone amount ranges from -6.5% to +6.9% due to transmittance error, from -9.5% to +10.5% due to temperature error, and from -5.1% to +5.4% due to pressure error, respectively. The present study suggests that accurate vertical ozone profile can be retrieved from satellite solar occultation method. Accuracy of vertical temperature profile is especially important in the retrieval of vertical ozone profile.

• The Journal of Korean Academy of Prosthodontics
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• v.59 no.3
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• pp.261-270
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• 2021

Purpose. The aim of this study was (1) to compare the reverse engineering technique with other existing measurement methods and (2) to analyze the effect of implant angulations and impression coping types on implant impression accuracy with reverse engineering technique. Materials and methods. Three different master models were fabricated and the distance between the two implant center points in parallel master model was measured with different three methods; digital caliper measurement (Group DC), optical measuring (Group OM), and reverse engineering technique (Group RE). The 90 experimental models were fabricated with three types of impression copings for the three different implant angulation and the angular and distance error rate were calculated. One-way ANOVA was used for comparison among the evaluation methods (P < .05). The error rates of experimental groups were analyzed by two-way ANOVA (P < .05). Results. While there was significant difference between Group DC and RE (P < .05), Group OM had no significant difference compared with other groups (P > .05). The standard deviations in reverse engineering were much lower than those of digital caliper and optical measurement. Hybrid groups had no significant difference from the pick-up groups in distance error rates (P > .05). Conclusion. The reverse engineering technique demonstrated its potential as an evaluation technique of 3D accuracy of impression techniques.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.22 no.4
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• pp.78-96
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• 2023

Urban traffic information is collected by various systems such as VDS, DSRC, and radar. Recently, with the development of deep learning technology, smart intersection systems are expanding, are more widely distributed, and it is possible to collect a variety of information such as traffic volume, and vehicle type and speed. However, as a result of reviewing related literature, the performance evaluation criteria so far are rbs-based evaluation systems that do not consider the deep learning area, and only consider the percent error of 'reference value-measured value'. Therefore, a new performance evaluation method is needed. Therefore, in this study, individual error, interval error, and overall error are calculated by using a formula that considers deep learning performance indicators such as precision and recall based on data ratio and weight. As a result, error rates for measurement value 1 were 3.99 and 3.54, and rates for measurement value 2 were 5.34 and 5.07.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2009.11a
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• pp.269-272
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• 2009

본 논문에서는 변이지도의 정확도 향상을 위하여, 비용 함수를 이용한 교차 일치성 검사 기법을 제안하고, 다양한 조건의 실험을 통하여 제안한 알고리듬이 효율적임을 보였다. 좌우 변이정보를 이용하는 교차 일치성 검사로 오정합을 검출하는 방법을 시도해왔다. 하지만 이러한 방법은 물체의 경계에서 발생하는 오정합을 찾기가 어렵다. 본 논문에서는 최종 변이의 신뢰도 향상을 위해 교차 일치성 검사의 정확도를 높이는 방법을 제안하였다. 일반적으로 영역 기반 스테레오정합 방법은 물체의 경계에서 정확도 높지 못하다. 이러한 문제점을 해결하기 위해 정합창의 크기를 늘리거나 특징 점을 이용한 적응적 가변 정합창을 적용하는 방법을 시도하였다. 하지만, 여전히 기존 교차 일치성 검사를 통한 오정합 검출은 부정확하다. 이러한 영역의 비용 함수 값들을 비교한 결과 첫 번째와 두 번째 값의 차이가 적거나 크게 나타난다. 제안한 방법은 기존 방법에 비해 오정합 검출 능력을 향상 시킨다. 제안한 방법의 결과를 확인하기 위해 스테레오 비전에서 많이 사용되는 영상을 적용하고 분석하였다. 또한, 기존 교차 일치성 검사 방법과 제안한 방법의 객관적으로 비교하기 위해 전체 영역에 대한 오차율 (error ratio)과 교차 일치성 검사로 유효하다고 판단된 변이 값 중 실제 변이 값과 일치하지 않은 변이값의 오차율을 비교하였다. 실험 결과 기존 방법에 비해 제안한 방법이 1~5%정도 낮은 오차율을 보였다

• The Journal of the Korea Contents Association
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• v.16 no.5
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• pp.104-112
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• 2016

The Adaboost chooses a good set of features in rounds. On each round, it chooses the optimal feature and its threshold value by minimizing the weighted error of classification. The involved process of classification performs a hard decision. In this paper, we expand the process of classification to a soft fuzzy decision. We believe this expansion could allow some flexibility to the Adaboost algorithm as well as a good performance especially when the size of a training data set is not large enough. The typical Adaboost algorithm assigns a same weight to each training datum on the first round of a training process. We propose a new algorithm to assign different initial weights based on some statistical properties of involved features. In experimental results, we assess that the proposed method shows higher performance than the traditional one.