• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2007년도 추계학술대회 논문집
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• pp.517-518
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• 2007

• 한국군사과학기술학회지
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• 제23권1호
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• pp.52-58
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• 2020

In this paper, a 2-dimensional phase comparison direction finding receiver was designed and fabricated. For 2-D comparison direction finding, direction finding formulas were derived from a uniformly arranged of four antennas. Based on this, a direction finding receiver was designed using Matlab simulink, and the direction finding receiver was fabricated. To analyze the performance of the designed direction finding receiver, the injection direction finding accuracy and simulation results were compared. As a result of the test, the fabricated direction finding receiver showed a maximum of 3° RMS precision, and the result of both tests showed similar trends. Also, it was confirmed that the direction finding accuracy of elevation angle is about 2.7 times better than azimuth angle, and both models performed well within 0.7° RMS at the boresight.

• 한국농업기계학회:학술대회논문집
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• 한국농업기계학회 2000년도 하계 학술대회 논문집
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• pp.275-280
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• 2000

• 융합정보논문지
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• 제7권5호
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• pp.83-88
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• 2017

본 논문은 F-16 전투기 축소모델을 사용한 위상비교 방향 탐지 장치의 방위각 정확도 시험에 대해서 기술하였다. 전투기 하부면에 안테나를 배치하면 항공기 구조물에 의한 전파 반사가 일어나서 방위각 측정오차가 발생한다. 본 연구에서는 F-16 전투기를 5:1로 축소 모델링하고 전투기 하부면에 5개 안테나를 원형으로 설치한 다음 $0-360^{\circ}$ 방위각에서 $1^{\circ}$ 간격으로 전파를 수신하였다. 이 때 5개 안테나에 수신되는 전파의 위상을 수치해석으로 계산하여 방향 탐지정확도 시험을 실시하였다. 축소모델을 사용해서 시험한 위상비교 방향 탐지 방식의 방위각 오차는 신호잡음세기가 0dB 이상인 경우 평균 $0.5^{\circ}$ 이하로 측정되어서 전투기의 위상비교 방향 탐지 장치 설계에 유용하게 활용할 수 있을 것으로 판단된다.

• Journal of Trauma and Injury
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• 제22권2호
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• pp.148-153
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• 2009

Purpose: The osmolar gap increases in proportion to the ethanol level. Some previous studies have shown that the correlation between the osmolar gap and the ethanol level is weak in trauma patient by using an indirect comparison with other patients. We conducted a direct comparison of the correlation of the osmolar gap to the ethanol level between trauma patients and non-trauma patients. We also analyzed the accuracy of the estimated ethanol level between the two groups. Methods: The research candidates were adult patients who had visited the emergency department of our hospital from December 2003 to November 2008. By using a retrospective chart review, we classified them into three subgroups: non-trauma without shock, trauma without shock, and trauma with shock. In each group, we compared the correlation between the osmolar gap and the measured ethanol level, and we analyzed the accuracy of the estimated ethanol level by using Lin's concordance correlation coefficient. Results: Four hundred forty-seven patients were enrolled in this study. For correlation of the osmolar gap and the measured ethanol level, Pearson's correlation coefficient was 0.916 in all patients, 0.939 in non-trauma without shock patients, 0.917 in trauma without shock patients, and 0.844 in trauma with shock patients. In the analysis of the accuracy of the estimated ethanol level by using Lin's concordance correlation coefficient, the accuracy in trauma with shock patients was lower than that in non-trauma without shock patients. Conclusion: We found that the correlation between the osmolar gap and the measured ethanol level in the patient group with trauma was lower than it was in the patient group without trauma. Moreover trauma patients with shock had a lower accuracy of the estimated ethanol level than non-trauma patients.

• Journal of Astronomy and Space Sciences
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• 제39권4호
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• pp.159-167
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• 2022

Because of the small number of spacecraft available in the Earth's magnetosphere at any given time, it is not possible to obtain direct measurements of the fundamental quantities, such as the magnetic field and plasma density, with a spatial coverage necessary for studying, global magnetospheric phenomena. In such cases, empirical as well as physics-based models are proven to be extremely valuable. This requires not only having high fidelity and high accuracy models, but also knowing the weakness and strength of such models. In this study, we assess the accuracy of the widely used Tsyganenko magnetic field models, T96, T01, and T04, by comparing the calculated magnetic field with the ones measured in-situ by the GOES satellites during geomagnetically disturbed times. We first set the baseline accuracy of the models from a data-model comparison during the intervals of geomagnetically quiet times. During quiet times, we find that all three models exhibit a systematic error of about 10% in the magnetic field magnitude, while the error in the field vector direction is on average less than 1%. We then assess the model accuracy by a data-model comparison during twelve geomagnetic storm events. We find that the errors in both the magnitude and the direction are well maintained at the quiet-time level throughout the storm phase, except during the main phase of the storms in which the largest error can reach 15% on average, and exceed well over 70% in the worst case. Interestingly, the largest error occurs not at the Dst minimum but 2-3 hours before the minimum. Finally, the T96 model has consistently underperformed compared to the other models, likely due to the lack of computation for the effects of ring current. However, the T96 and T01 models are accurate enough for most of the time except for highly disturbed periods.

• 제어로봇시스템학회논문지
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• 제5권1호
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• pp.88-94
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• 1999

This paper presents an accuracy evaluation method for muzzle velocity measurement systems. Among various measuring techniques, the solenoid coil scheme and the doppler radar scheme are considered due to their popularity in applications. The error sources are first identified and their effects on the accuracy of the measuring systems are quantified using mathmatical equations. The theoritic accuracy limits are then verified through comparison with experimental results. From the accuracy point of view, they turn out to be standard velocity measuring systems.

• Journal of Chest Surgery
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• 제29권1호
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• pp.52-58
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• 1996

Sixty six patients who were operated as lung cancer during the period from Mar. 1991 to Sep. 1993 at the department of Thoracic and cardiovascular surgery, were reviewed retrospectively and the accuracy of regional lymph node in preoperative CT were compared with histopathologlc report obtained from operation. The age ranged from 30 to 72 years old (mean age : 56.5), and 51 patients were male and 15 patients were female. The author analysed the true positive, true negative, false positive and false negative and sensitivity, specificity, positive predictive index, negative predictive index and accuracy of each nodes. The result is that there were differences between seven nodal groups in specificity, sensitivity, positive predictive Index, negative predictive index and accuracy. The range of each nodal group is from 81.7 to 98.3% The nodes of the most poor accuracy are aortopulmonary area and hilar area.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2000년도 추계학술대회 논문집
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• pp.330-333
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• 2000

Dimensional accuracy and surface quality are very important in rapid prototyping especially when the models are used for the production of tools. This paper presents the development of benchmarking part to investigate dimensional accuracy and surface finish. A new test part is designed to perform benchmarking of major rapid prototyping processes such as selective laser sintering, laminated object manufacturing, stereolithography apparatus, and fused deposition modeling. The test part design includes basic manufacturing features such as holes, walls, squares, cylinder and etc. In addition, the small features are included in order to evaluate the fine details that can be manufactured by a specific RP process. The CMM program that automatically measures different features in the test part is also developed. The evaluation of accuracy as well as surface roughness are discussed for major rapid prototyping processes.

• 품질경영학회지
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• 제43권4호
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• pp.521-532
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• 2015

Purpose: The purpose of this study is to compare two multivariate cumulative sum (MCUSUM) charts designed for spatio-temporal surveillance in terms of not only temporal detection performance but also spatial detection performance. Method: Experiments under various configurations are designed and performed to test two CUSUM charts, namely SMCUSUM and RMCUSUM. In addition to average run length(ARL), two measures of spatial identification accuracy are reported and compared. Results: The RMCUSUM chart provides higher level of spatial identification accuracy while two charts show comparable performance in terms of ARL. Conclusion: The RMCUSUM chart has more flexibility, robustness, and spatial identification accuracy when compared to those of the SMCUSUM chart. We recommend to use the RMCUSUM chart if control limit calibration is not an urgent task.