• Journal of Practical Engineering Education
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• v.13 no.2
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• pp.393-403
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• 2021

The purpose of this study is to propose a method of designing a systematic panel survey at the institutional level to lay the foundation for data-based decision-making using vocational training teachers and instructors as the population. In this study, the target population and sampling frame, which are the main elements necessary for planning a panel survey, are proposed. Also based on expert advice and empirical data analysis, the sampling unit and sampling method taking into account the outer and inner variables are presented, comprehensively considering the representativeness of data, the efficiency and sustainability of data collection. As a result of the study, with the unit of the panel as a vocational training institution, a two-stage stratified proportional sampling plan is proposed so that the institution selected as the panel and the vocational training teachers and instructors belonging to the institution can participate in the survey. Based on this, implications for the panel survey sample design are presented.

• The Korean Journal of Applied Statistics
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• v.32 no.3
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• pp.349-374
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• 2019

A class imbalance problem arises when one class outnumbers the other class by a large proportion in binary data. Studies such as transforming the learning data have been conducted to solve this imbalance problem. In this study, we compared resampling methods among methods to deal with an imbalance in the classification problem. We sought to find a way to more effectively detect the minority class in the data. Through simulation, a total of 20 methods of over-sampling, under-sampling, and combined method of over- and under-sampling were compared. The logistic regression, support vector machine, and random forest models, which are commonly used in classification problems, were used as classifiers. The simulation results showed that the random under sampling (RUS) method had the highest sensitivity with an accuracy over 0.5. The next most sensitive method was an over-sampling adaptive synthetic sampling approach. This revealed that the RUS method was suitable for finding minority class values. The results of applying to some real data sets were similar to those of the simulation.

• The Journal of Korean Society for Radiation Therapy
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• v.23 no.2
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• pp.97-102
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• 2011

Purpose: IMRT QA using 2Dimensional array detector is carried out with condition for discrete dose distribution clinically. And it can affect uncertainty of evaluation using gamma method. We analyze gamma index variation according to grid size and suggest validate range of grid size for IMRT QA in Hospital. Materials and Methods: We performed QA using OniPro I'mRT system software version 1.7b on 10 patients (head and neck) for IMRT. The reference dose plane (grid size, 0.1 cm; location, [0, 0, 0]) from RTP was compared with the dose plane that has different grid size (0.1 cm, 0.5 cm, 1.0 cm, 2.0 cm, 4.0 cm) and different location (along Y-axis 0 cm, 0.2 cm, 0.5 cm, 1.0 cm). The gamma index variation was evaluated by observing the level of changes in Gamma pass rate, Average signal, Standard deviation for each case. Results: The average signal for each grid size showed difference levels of 0%, -0.19%, -0.04%, -0.46%, -8.32% and the standard deviation for each grid size showed difference levels of 0%, -0.30%, 1.24%, -0.70%, -7.99%. The gamma pass rate for each grid size showed difference levels of 0%, 0.27%, -1.43%, 5.32%, 5.60%. The gamma evaluation results according to distance in grid size range of 0.1 cm to 1.0 cm showed good agreement with reference condition (grid size 0.1 cm) within 1.5% and over 5% in case of the grid size was greater than 2.0 cm. Conclusion: We recognize that the grid size of gamma evaluation can make errors of IMRT QA. So we have to consider uncertainty of gamma evaluation according to the grid size and apply smaller than 2 cm grid size to reduce error and increase accuracy clinically.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 1999.06b
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• pp.109-114
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• 1999

동영상을 효율적으로 검색하기 위해서 동영상을 장면 단위로 분할하는 과정이 필요하다 이 논문에서는 동영상에서 장면이 전환되는 지점을 빠르게 검출하는 방법을 제안한다. 먼저 MPEG 압축 영상에 대하여 시간적 표본화를 통하여 추출된 압축 영역의 데이터를 사용하여 장면 전환의 후보 구간들을 정하고, 다음으로 이들 구간 안에서 각 프레임의 화소값을 얻고, 이를 사용하여 정확한 장면 전환 지점을 찾아낸다. 제안된 방법은 빠른 검출 속도와 함께 높은 정확성을 갖는다. 또한 카메라 플래시 때문에 장면 전환으로 잘못 검출되는 것을 방지할 수 있는 방법을 제안한다.

• Journal of Wetlands Research
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• v.20 no.2
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• pp.105-115
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• 2018

The frequency analysis of hydrometeorological data is one of the most important factors in response to natural disaster damage, and design standards for a disaster prevention facilities. In case of frequency analysis of hydrometeorological data, it assumes that observation data have statistical stationarity, and a parametric method considering the parameter of probability distribution is applied. For a parametric method, it is necessary to sufficiently collect reliable data; however, snowfall observations are needed to compensate for insufficient data in Korea, because of reducing the number of days for snowfall observations and mean maximum daily snowfall depth due to climate change. In this study, we conducted the frequency analysis for snowfall using the Bootstrap method and SIR algorithm which are the resampling methods that can overcome the problems of insufficient data. For the 58 meteorological stations distributed evenly in Korea, the probability of snowfall depth was estimated by non-parametric frequency analysis using the maximum daily snowfall depth data. The results of frequency based snowfall depth show that most stations representing the rate of change were found to be consistent in both parametric and non-parametric frequency analysis. According to the results, observed data and Bootstrap method showed a difference of -19.2% to 3.9%, and the Bootstrap method and SIR(Sampling Importance Resampling) algorithm showed a difference of -7.7 to 137.8%. This study shows that the resampling methods can do the frequency analysis of the snowfall depth that has insufficient observed samples, which can be applied to interpretation of other natural disasters such as summer typhoons with seasonal characteristics.

• Journal of Engineering Education Research
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• v.12 no.2
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• pp.89-95
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• 2009

This thesis investigated way of employment, education course of a training school of Programmable Logic Controller a Field. I inquired into a demand of an engineer and a necessary level of professional education. As a result, I have a purpose in what offer the information that cared for a beginning to work elevation and education training and boat development of a student more than. Faced a human power demand in an education demand and a field rehearsal student demand and analyzed it. The sample extraction used industrial classification, work of scale, Assignment sample extraction way (quota sampling). All data called at a silver phone and the investigated, The data parser analyzed the statistics that used Microsoft Excel.

• Journal of Engineering Education Research
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• v.11 no.3
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• pp.90-95
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• 2008

This thesis investigated way of employment, education course of a training school of electrical company. I inquired into a demand of an engineer and a necessary level of professional education. As a result, I have a purpose in what offer the information that cared for a beginning to work elevation and education training and boat development of a student more than. Faced a human power demand in an education demand and a field rehearsal student demand and analyzed it. The sample extraction used industrial classification, work of scale, Assignment sample extraction way (quota Sampling). All data called at a silver phone and the investigated, The data parser analyzed the statistics that used Microsoft Excel.

• The Korean Journal of Applied Statistics
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• v.34 no.6
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• pp.889-904
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• 2021

This study is a follow-up study of Kang and Kim (2020). In this study, we derive the sample influence functions of the t-statistic which were not directly derived in previous researches. Throughout these results, we both mathematically examine the relationship between the empirical influence function and the sample influence function, and consider a method to approximate the sample influence function by the empirical influence function. Also, the validity of the relationship between an approximated sample influence function and the empirical influence function is verified by a simulation of a random sample of size 300 from normal distribution. As a result of the simulation, the relationship between the sample influence function which is derived from the t-statistic and the empirical influence function, and the method of approximating the sample influence function through the empirical influence function were verified. This research has significance in proposing both a method which reduces errors in approximation of the empirical influence function and an effective and practical method that evolves from previous research which approximates the sample influence function directly through the empirical influence function by constant revision.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.15 no.6
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• pp.3774-3780
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• 2014

This study examined green tea fermented by the addition of sun-dried salt to increase the extraction of Procyanidins and Gallic acid and Theaflavins. An experiment on the change in the amount of the extract according to the saturation degree of sun-dried salt was performed. The sample of fermented only green tea extracted only Gallic acid (0.004 mg/g). No Procyanidins and Theaflavins were extracted. When the green tea was fermented by sun-dried salt, large amounts of the three compounds were extracted: Procyanidins, 75%(0.244 mg/g) and 100%(0.949 mg/g); Gallic acid, 75%(0.386 mg/g) and 100%(0.691 mg/g), and Theaflavins, 75%(0.083 mg/g). According to the date of fermentation, the largest amount of Procyanidins, Gallic acid and Theaflavins extracted were on the 2nd day(0.295 mg/g) and 7th day(2,256 mg/g) and 4th day(0.168 mg/g), respectively.

• Proceedings of the KAIS Fall Conference
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• 2003.06a
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• pp.143-145
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• 2003

본 논문은 벤처기업을 합리적으로 평가할 수 있는 평가모형과 방법을 제시할 목적으로 코스닥 등록기업 중 무작위추출에 의해 선정된 99개 빈처기업을 분석표본으로 삼았으며 기업별 시장주가로 2000년 1월부터 2001년12월까지의 최고, 최저, 평균주가를 추출하였다. 본 논문에서는 벤처기업가치평가 모형으로 실물옵tus 평가 모형 쿵 성장옵션모형을 이용하여 각 기업의 현재가격, 행사가격, 변동성, 행사기간, 무위험이자율의 5개 변수로 벤처기업의 옵션가치를 산출하고 여기에 잔존가치를 현금흐름 할인법으로 한인 산출하여 그 값을 합하여 기업가치를 평가하였고 또한 현금흐름 할인법(DCF)을 이용하여 기업가치를 평가하였다. 여기에 사용된 각종 파라미터 값은 우리나라 벤처기업과 산업의 자료를 중심으로 추출하여 본 모형에 적용, 기업의 가치를 실증적으로 평가하였다.