• Journal of the Optical Society of Korea
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• v.19 no.2
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• pp.165-168
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• 2015

A simple method to determine the focal length of a lens using the Talbot image is presented. This method uses only one grating, requiring neither Moir$\acute{e}$ fringe analysis nor the angle between the gratings. The original Fourier transform was used to access the spectrum beyond the limitation set of the usual fast Fourier transform to determine the (de)magnification accurately enough to be used for the focal length. A set of Talbot images simulated numerically with the Fresnel diffraction integral was used to demonstrate the method. For focal lengths between 5550 mm and 5650 mm, the mean difference between the focal lengths determined from the Talbot images and the true values was 3.3 mm with the standard deviation of the difference being 3.8 mm. The true focal lengths can be recovered with an accuracy of 0.06%.

• Honam Mathematical Journal
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• v.30 no.3
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• pp.581-587
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• 2008

In this paper, to have a better a posteriori error bound of the average case error between the true value of I(f) and the Trapezoidal rule on subintervals using zero mean-Gaussian, we prove that a new average error between the difference of the true value of I(f) from the composite Trapezoidal rule and that of the composite Trapezoidal rule from the simple Trapezoidal rule is bounded by $c_rH^{2r+3}$ through direct computation of constants $c_r$ for r ${\leq}$ 2 under the assumption that we have subintervals (for simplicity equal length h) partitioning [0, 1].

• Journal of Institute of Control, Robotics and Systems
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• v.13 no.6
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• pp.525-530
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• 2007

In this paper, a performance comparison between traditional TPN (true proportional navigation) guidance law and PPN(pure proportional navigation) guidance law is made, based on a short range surface-to-air missile simulation program. This simulation program has a nonlinear aerodynamic missile model, a roll stabilized autopilot, a nonlinear radar model, and a target model, According to the simulation results, the PPN guidance law has better performances than TPN guidance law under the condition of evasive target.

• Advances in pediatric surgery
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• v.2 no.1
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• pp.53-58
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• 1996

Congenital duplication of the gallbladder, including true duplication and septated gallbladder, is an uncommon but potentially complicated malformation. It presents biliary colic associated with acute or chronic cholecystitis. It can be diagnosed preoperatively by various imaging tools such as real-time ultrasonography, biliary scintigraphy, oral cholecystography, or endoscopic retrograde cholangiography. It can be safely managed by either laparoscopic or open procedures. This report describes a 6-year-old girl with true duplication of gallbladder diagnosed preoperatively by real-time ultrasonography and treated by open cholecystectomy.

• Journal of Gifted/Talented Education
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• v.7 no.1
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• pp.77-116
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• 1997

The paper-and-pencil multiplce choise test has been widely used to identify gifted and talented student in Korea. Such test have several drawbacks; such~a s not being able to assess creative problem solving abilities and high level thinking abilities which are important characteristics of gifted students. The Korean Educational Development Institute (KEDI) developed a performance assessment which challenged traditional methods of identification. The 5-day summer camp was held to select gifted students for the Korean Minjok Leadership Academy. 211 students were evaluated in the aspects of creative problem solving abilities, high level thinking abilities, task commitments, and cooperativeness with various performance tasks, such as essay tests, conversations, oral examinations, computer simulations, puzzles, experiments, group discussions, debates, research reports, and games. As a result, it was found that there were several limitations of the performance assessment in terms of low reliability, requiring high costs and many professionals, and taking long times and large spaces. Expanding and continuing research should follow in order for a performance assessment to use widely as an identification methods because it assesses 'true' abilities of each individual student. follow in order for a performance assessment to use widely as an identification methods because it assesses 'true' abilities of each individual student.

• 대한예방의학회:학술대회논문집
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• 1994.02b
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• pp.142-149
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• 1994

Substitution of graphic representation for extensive lists of numerical statistical data is highly desirable by both editors and readers of medical journals, faced with an exploding abundance of contemporary medical literature. A novel graphic tool. the 'double-ring diagram', is described herein which permits visual representation of information regarding certain statistical variables used to describe the performance of a test or physical sign in the diagnosis of a disease. The diagram is relatively easy to construct on the basis of a number of primary data such as the prevalence and the true positive, true negative. false positive and false negative test results. These values are reflected in the diagram along with the values of other statistical variables derived from them. such as the sensitivity. specificity, predictive values for positive and negative test result. and accuracy. This diagram may be useful in visualizing a test's performance and facilitating visual comparison of performance of two or more tests.

• Journal of the Korean Data and Information Science Society
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• v.25 no.6
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• pp.1521-1530
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• 2014

The ROC analysis is considered for multiple class diagnosis. There exist many criteria to find optimal thresholds and measure the accuracy of diagnostic tests for k dimensional ROC analysis. In this paper, we proposed a diagnostic accuracy measure called the correct classification simple rate, which is defined as the summation of true rates for each classification distribution and expressed as a function of summation of sequential true rates for two consecutive distributions. This measure does not weight accuracy across categories by the category prevalence and is comparable across populations for multiple class diagnosis. It is found that this accuracy measure does not only have a relationship with Kolmogorov - Smirnov statistics, but also can be represented as a linear function of some optimal threshold criteria. With these facts, the suggested measure could be applied to test for comparing multiple distributions.

• Journal of Korean Institute of Industrial Engineers
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• v.14 no.2
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• pp.91-97
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• 1988

In accelerated life testing, a relationship is usually assumed between the stress and a parameter of the lifetime distribution. However, the true relationship is not usually known, and therefore, the experimenter may wish to provide protections against the likely departures from the assumed relationship. This paper considers an accelerated life test in which two stress levels are involved, and the lifetime of each test item at a stress level is assumed to have an independent, identical, exponential distribution. For the case where a first order relationship is assumed while the true one is quadratic, a procedure is developed for allocating test items to stress levels such that the bias and/or the variance of the estimated(log-transformed) mean lifetime at the use condition is minimized.

• Proceedings of the Korea Contents Association Conference
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• 2018.05a
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• pp.179-180
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• 2018

최근 N스크린 세대의 새로운 소비 주도층인 밀레니얼세대(10대~20대 초반)의 증가로 모바일 YouTube 동영상 시청자가 증가하였다. 이로 인해 광고 노출 가능성이 높아지고 있어 YouTube 인스트림 광고가 광고주들의 높은 주목을 받고 있다. 그러나 현재 광고 게재에 따른 정확한 노출 효과에 대한 연구 분석 자료는 현저히 부족하다. 이에 모바일 YouTube 동영상 시청자 수가 가장 높은 10대~20대 초반을 대상으로 국내 YouTube 인스트림 광고 사례 10개를 선정하여 선택적 시청에 따른 시청자들의 행태 파악과 광고 몰입도를 분석해 보았다. 분석 결과 소구 유형별 광고 몰입도는 이성소구보다 감성소구가 컸으며, 그 중 유머소구의 광고 몰입도가 가장 크게 나타났다. 본 연구 결과가 향후 광고 노출 효과를 높이는데 도움이 되기를 기대한다.

• Magazine of the Korean Society of Agricultural Engineers
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• v.23 no.2
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• pp.45-53
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• 1981

Long term precipitation gaging station record (58 years) was analyzed by progressive mean method to compare the estimated effective period of records for computing mean and probable values. Obtained results are as follows: 1. Fifty-eight years precipitation records at Jinju, Gyeong Sang Nam Do was analyzed by double mass analysis method. Result was appeared that the record was consistent with time. 2. The effective period of records for estimating mean values with the departure of 5% or less from the true mean are up to 33 years for annual precipitation, 20 years for annual maximum daily precipitation and 45 years for maximum successive dry days in summer season. 3. To estimate the probable values by Gumbel-Chow method within the departure of 5% level from true value, periods of 51 years, 38 years and 45 years were required for annual precipitation, annual maximum daily precipitation and maximum successive dry days in summer season, respectively.