• 조명전기설비학회논문지
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• 제28권6호
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• pp.7-14
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• 2014

We proposed a new algorithm to improve the calculation speed of forward ray tracing method which was quite a problem in conventional Monte Carlo algorithm. To verify the accuracy and the effect of improving calculation speed, we directly compared integrating sphere characteristics with conventional ray tracing algorithm under the same condition which was referred in a reference paper. By applying new algorithm to an absolute reflectometer, we calculated the degree of errors which were caused by baffle and port characteristics to find optimal system design condition.

• 한국정보시스템학회지:정보시스템연구
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• 제26권3호
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• pp.63-90
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• 2017

Purpose This study proposes a novel system trading model using case-based reasoning (CBR) based on absolute similarity threshold. The proposed model is designed to optimize the absolute similarity threshold, feature selection, and instance selection of CBR by using genetic algorithm (GA). With these mechanisms, it enables us to yield higher returns from stock market trading. Design/Methodology/Approach The proposed CBR model uses the absolute similarity threshold varying from 0 to 1, which serves as a criterion for selecting appropriate neighbors in the nearest neighbor (NN) algorithm. Since it determines the nearest neighbors on an absolute basis, it fails to select the appropriate neighbors from time to time. In system trading, it is interpreted as the signal of 'hold'. That is, the system trading model proposed in this study makes trading decisions such as 'buy' or 'sell' only if the model produces a clear signal for stock market prediction. Also, in order to improve the prediction accuracy and the rate of return, the proposed model adopts optimal feature selection and instance selection, which are known to be very effective in enhancing the performance of CBR. To validate the usefulness of the proposed model, we applied it to the index trading of KOSPI200 from 2009 to 2016. Findings Experimental results showed that the proposed model with optimal feature or instance selection could yield higher returns compared to the benchmark as well as the various comparison models (including logistic regression, multiple discriminant analysis, artificial neural network, support vector machine, and traditional CBR). In particular, the proposed model with optimal instance selection showed the best rate of return among all the models. This implies that the application of CBR with the absolute similarity threshold as well as the optimal instance selection may be effective in system trading from the perspective of returns.

• 한국측량학회지
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• 제25권6_2호
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• pp.635-643
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• 2007

국내에 고해상도 지도제작용 항공디지털카메라 영상의 도입 및 공급이 현실화됨에 따라 항공디지털카메라 영상을 이용한 수치지도의 제작 및 갱신에 많은 관심이 모아지고 있다. 본 연구는 푸쉬부룸 항공디지털카메라 영상을 이용하여 기존의 1/1,000 수치지도의 갱신방법을 제시하고자 하였다. GPS측량성과를 이용하여 기하보정을 수행하고, 수치도화를 위해 수치사진측량시스템을 이용하였다. 수치도화는 건물 및 도로를 묘사하였고, GPS측량성과를 이용하여 절대위치정확도 평가와 해석도화에 의해 제작된 수치지도를 이용하여 상대위치정확도 평가를 수행하였다. 절대위치정확도 평가결과, RMSE가 X, Y축으로 각각 ${\pm}0.172m,\;{\pm}0.127m$, 평균거리오차는 0.208m, 상대위치정확도 평가결과, RMSE가 X, Y축으로 각각 ${\pm}0.238m,\;{\pm}0.281m$, 평균거리오차는 0.337m로 나타났다. 따라서, 본 연구에서 제시한 항공디지털카메라 영상을 이용한 수치지도 갱신방법은 국토지리정보원 규정의 허용오차 이내였으므로, 향후 국가기본도 제작은 물론 지자체의 GIS사업 및 다양한 분야에 활용할 수 있다.

• 한국대기환경학회지
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• 제16권3호
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• pp.265-275
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• 2000

By using thermal desorption/gas chromatograph/flame ionization detector(TD/GC/FID), this study was carried out to evalute an accuracy and a precision on Benzene(B), Toluene(T), o-Xylene(X) analysis in an industrial hygiene laboratory. Limits of detection of TD/GC/FID on B, T, X were showed 13.75ng/sample or less. For the accuracy of the method by concentration levels, overall bias was showed 7.7% as an absolute value, and the pooled coefficient of variation showed 3.51%. For the precision on repeatability of peak area and retention time between within-run and between-run of analytical system, it is showed the results of within-run gave better than those of between-run. Also the accuracy by sorbents(Tenax TA and Chromosorb 106)was evaluated, and the precision on reproducibility between MDHS72 and this study was compared. It is showed it is possible for TD/GC/FID to evaluate accurately B, T, X concentration levels of less than 1ppm at indoor or outdoor of workplaces in Korea.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2001년도 춘계학술대회 논문집
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• pp.135-139
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• 2001

This paper describes a string resonator that is used for the interrogation system of a Fiber Bragg Grating(FBG) strain sensor. The strain on the fiber piece is calculated from the measured frequency based on that the natural frequency of a string is a function of the applied absolute strain. Existing research considered a fiber as a string, but a fiber is not a string in the strict sense due to its bending stiffness, thus the fiber should be modeled as a beam accompanied with an axial force. In the vibration modeling, the relationship between the strain and the natural frequency is derived, and then the resonance condition is described in terms of both the phase and the mode shape for sustaining resonant motion. Several experiments verify the effectiveness of the proposed model of the fiber. The performance of the string resonator is analyzed by measuring the frequency change according to the applied strains in the dynamic range of 1100$\mu\varepsilon$ referred to the displacement from capacitance sensor. From the experimental results, the implemented string resonator provides the accuracy of $\pm$3$\mu\varepsilon$, the quasi-static resolution of ~0.1$\mu\varepsilon$(rms) which amount to be $\pm$0.17$\mu\textrm{m}$ and ~6nm respectively, in case of fiber length of 56mm. For a dynamic strain, it can provide the accuracy of ~3$\mu\varepsilon$ until the frequency comes to 8Hz. As a consequence, the string resonator proposed for FBG sensor provides the high accuracy and the high resolution in strain measurement, and also it is expecting to be used, for the application, to not only strain but also displacement measuring device.

• 대한인간공학회지
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• 제19권2호
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• pp.87-99
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• 2000

This study aims to examine a fuzzy logic-based human expert EMG prediction model (FLHEPM) for predicting electromyographic responses of trunk muscles due to manual lifting based on two task (control) variables. The FLHEPM utilizes two variables as inputs and ten muscle activities as outputs. As the results, the lifting task variables could be represented with the fuzzy membership functions. This provides flexibility to combine different scales of model variables in order to design the EMG prediction system. In model development, it was possible to generate the initial fuzzy rules using the neural network, but not all the rules were appropriate (87% correct ratio). With regard to the model precision, the EMG signals could be predicted with reasonable accuracy that the model shows mean absolute error of 8.43% ranging from 4.97% to 13.16% and mean absolute difference of 6.4% ranging from 2.88% to 11.59%. However, the model prediction accuracy is limited by use of only two task variables which were available for this study (out of five proposed task variables). Ultimately, the neuro-fuzzy approach utilizing all five variables to predict either the EMG activities or the spinal loading due to dynamic lifting tasks should be developed.

• 제어로봇시스템학회논문지
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• 제13권10호
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• pp.949-955
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• 2007

This paper proposes an efficient localization algorithm in the RFID sensor space for the precise localization of a mobile robot. The RFID sensor space consists of embedded sensors and a mobile robot. The embedded sensors, that is tags are holding the absolute position data and provide them to the robot which carries a reader and requests the absolute position fur localization. The reader, it is called as antenna usually, gets several tag data at the same time within its readable range. It takes time to read all the tags and to process the data to estimate the position, which is a major factor to deteriorate the localization accuracy. In this paper, an efficient algorithm to estimate the position and orientation of the mobile robot as quickly as possible has been proposed. Along with the algorithm, a new allocation of the tags in the RFID sensor space is also proposed to improve the localization accuracy. The proposed algorithms are demonstrated and verified through the real experiments.

• Journal of the Optical Society of Korea
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• 제18권4호
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• pp.335-340
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• 2014

Based on Zernike polynomial fitting, we propose an algorithm believed to be new for interferometric measurements of rotationally asymmetric surface deviation of optics. This method tests and calculates each angular surface by choosing specified rotation angles with lowest error. The entire figure can be obtained by superimposing these sub-surfaces. Simulation and experiment studies for verifying the proposed algorithm are presented. The results show that the accuracy of the proposed method is higher than single-rotation algorithm and almost comparable to the rotation-averaging algorithm with fewer rotation measurements. The new algorithm can achieve a balance between the efficiency and accuracy.

• 한국측량학회지
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• 제19권1호
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• pp.1-8
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• 2001

본 연구는 SA가동 중단 후 GPS절대 측위 정확도의 향상 정도를 파악하는데 있다. 이를 위해 SA가동 중단 전후의 GPS C/A코드 의사 거리를 이용하여 위성 시계 오차량과 관측점 좌표를 산출하였으며, 이를 JPL 정밀궤도력에 포함되어 있는 위성 시계 오차량 및 관측점의 기지성과와 비교하였다. 비교 결과, GPS 위성 시계 오차 보정량은 SA가동시 약 $\pm$ 40m폭으로 변동을 보인 반면, SA중단 후 $\pm$2m이내로 급격히 감소되었음을 알 수 있었으며, 3차원 좌표성과에 대한 95% 확률오차는 SA 가동시 약 $\pm$65m 였으나, 가동 중단후 X. Y는 약 $\pm$10m, Z는 약 $\pm$15m로 GPS 절대 측위 정확도가 상당히 향상되었음을 알 수 있었다.

• 한국측량학회:학술대회논문집
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• 한국측량학회 2010년 춘계학술발표회 논문집
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• pp.285-287
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• 2010

It is recently enlarged to necessity of 3D spatial information model in urban areas. and in order to that, It is increased to use the terrestrial LiDAR. The Point clouds which are received by terrestrial LiDAR take a relateive coordinate. For transform into absolute coordinate, it carry out GPS surveying. However, it is difficult to geo-referencing of point clouds using the GPS due to high buildings and facilities in urban area. This study suggests a methodology, that is geo-referencing of point clouds which is received from terresstrial LiDAR in urban area and then verified accuracy of geo-referencing of point clouds. In order to geo-Referencing of point clouds which are received in Engineering building of Yonsei Univ., it was be setout through GPS surveying, and then obtained absolute coordinate of real building. Using this coordinate, It was operated geo-referencing of point clouds, verified accuracy between check point and geo-referenced point clouds. As a result, RMSE of check point shows that GPS surveying is 6.9~8.0cm.