• Communications for Statistical Applications and Methods
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• v.4 no.2
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• pp.327-332
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• 1997

다층 신경망은 비모수 회귀함수 추정의 한 방법이다. 다충 신경망을 학습시키기 위해 역전파 알고리즘이 널리 사용되고 있다. 그러나 이 알고리즘은 이상치에 매우 민감하여 이상치를 포함하고 있는 자료에 대하여 원하지 않는 회귀함수를 추정한다. 본 논문에서는 통계물리에서 자주 사용하는 방법을 이용하여 로버스트 역전파 알고리즘을 제안하고 수학적으로 신경망과 매우 유사한 PRP(projection pursuit regression) 방법, 일반적인 역전파 알고리즘과 모의실험을 통해 비교 분석한다.

• Proceedings of the Korea Information Processing Society Conference
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• 2015.10a
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• pp.1786-1787
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• 2015

무안경 3차원 입체영상 시스템은 광고 패널, 공연 전시 등에 활용되고 있다. 본 연구에서는 무안경식 입체영상 시스템의 디스플레이로 활용되고 있는 렌티큘러 방식 3차원 입체 영상에 대해 화질변화에 따른 사용자의 반응을 뇌파 (Electroencephalogram, EEFG) 측정을 통해 분석하였다. 총 26명의 피험자를 대상으로 렌티큘러 방식의 디스플레이를 통해 최적입체영상과 왜곡입체영상을 차례로 제시하고 각 영상에 대해 획득한 뇌파를 통계 분석하여 상관관계를 확인하였다. 분석 결과 뇌파진동 중 알파파의 경우 최적입체영상과 왜곡입체영상 사이에서 통계적으로 유의미한 차이가 확인되지 않았으나 베타파의 경우 통계적으로 유의미한 차이가 확인되었다. 베타파의 경우 왜곡입체영상에서 최적입체영상보다 통계적으로 유의미하게 높게 나타났으며 이는 왜곡입체영상 시청 시 피로감 또는 불안감 증폭에 따른 베타파의 뇌파활동이 높아진 것으로 예상된다. 본 연구결과를 바탕으로 랜티큘러 방식의 무안경 입체영상에 대한 객관적 사용자 평가를 위해 뇌파분석을 활용한 접근 방법이 가능함을 확인하였다.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2022.06a
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• pp.167-170
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• 2022

2022년은 세계 최초로 지상파 UHD 본방송이 2017년에 시작되고 5년이 경과한 시점이다. 이제는 과거의 추진 경과를 살펴보고 기술의 발전과 미디어 환경 변화에 필요한 정책을 새롭게 추진하는 노력이 필요한 시점이라고 할 수 있다. 2015년에는 "지상파 UHD 방송 도입을 위한 정책 방안"이 마련되고, 2020년에는 "지상파 UHD 방송 활성화 방안"이 수립되어 지상파 UHD 방송 추진의 중심 역할을 수행하였다. 시청자가 원하는 지상파 UHD 방송은 어떤 모습이고, 불편한 점은 무엇인지, 어떤 점을 개선해 주면 좋은지에 대한 질문과 그에 대한 답을 찾는 노력은 아쉬움이 남는다. 시청자들은 UHD 방송 화질에 만족하는지? HDTV를 UHD TV로 교체하기 위한 필요·충분조건은 무엇인지에 대한 질문의 답변을 지속적으로 분석할 필요가 있다. 지상파 방송사와 UHD KOREA는 그동안 조사한 시청자의 지상파 UHD 방송에 대한 통계자료를 분석하고 정리하였다. 이를 토대로 새로운 미디어 환경에 필요하고 UHD 미디어 정책 수립과 추진에 기여할 수 있는 시청자 조사와 분석을 지속적으로 추진하려고 한다.

• Journal of the Korean Society for Marine Environment & Energy
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• v.16 no.1
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• pp.36-41
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• 2013

In this paper time series wave data are simulated using wave spectrum with random phases of the wave signal. The simulated wave signals are used to study the effect of the sampling rate on the ocean wave characteristics. Effect of sampling rate on wave data which include extreme wave such as freak waves are examined and various wave characteristics including abnormality index (AI), kurtosis of wave profile and maximum wave height are examined. Various wave heights are decreased as the sampling rate decreases. The zero-th moment of the wave spectrum does not affect much on the sampling rate but the second moment are greately affected on the sampling rate. The error due to the sampling rate is decreases as the wave period increases. The error in significant wave height based on the wave spectrum $H_s$ is smaller than that on the time domain method $H_{1/3}$. AI index and kurtosis of wave profile do not deviate much from the exact date as long as the sampling rate is greater than 1 Hz. Ocean wave measurement with the sampling frequency higher than 1 Hz will result the error less than 5% in estimating the height of extreme waves.

• Proceedings of the Korean Society of Coastal and Ocean Engineers Conference
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• 1993.07a
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• pp.137-141
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• 1993

최근 천해역에서의 파랑의 변화양상에대한 많은 연구가 수행되어 괄목할만한 진전을 보였으나 그 연구범위가 단일한 형태의 파랑을 대상으로한 확정론적인 접근방법에 치우쳐 있었다. 그러나 해수면의 상당 부분은 언제나 불규칙한 파랑에 의해 점유되어 있다. 이러한 불규칙성은 바람의 mechanical energy가 해수면으로 전이되는 과정에 기인하는 데 ［Phillips, 1980］ 따라서 파랑장의 해석에는 통계적인 방법이 이용되곤한다. (중략)

• Journal of Practical Agriculture & Fisheries Research
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• v.21 no.1
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• pp.49-59
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• 2019

The field trial was performed to evaluate the rice growth and yield in different direct seeding methods after Italian Ryegrass Harvest The required time for seed emergence was for 7 ~ 8days in the tested direct seeding methods and there was high in seedling establishment in order of wet hill-seeding with iron-coated seeds > water seeding with iron-coated seeds > wet hill-seeding with soil coverage with pregerminated seeds. The rice plant height was shorter in the tested direct seeding methods than that of machine transplanting until 45day after seeding but there was not significant difference in terms of statistical analysis at 63day after seeding. The growth of tiller number in the rice plant was high in water seeding with iron-coated seeds and wet hill-seeding with soil coverage and low in wet hill-seeding with iron-coated seeds compared to machine transplanting. The yield component in the tested direct seeding methods was not significant difference in terms of statistical analysis. The milled rice yield in the tested direct seeding methods was higher 2 ~ 8% being with 4.94 ~ 5.24t/ha than that of machine transplanting but there was not significant difference in terms of statistical analysis. The percentage of head rice was low in the tested direct seeding methods compared to machine transplanting. The weedy rice was not occurred in the tested rice cultivation methods. In conclusion the direct seeding method would be recommended to be a suitable to in following by Italian ryegrass harvesting in southern area of Korea in terms of reduction in production cost and high income basis for rice growing farmers.

• The Korean Journal of Applied Statistics
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• v.12 no.2
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• pp.505-515
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• 1999

인공신경망 모형을 적합시키는데 사용하는 역전파 알고리즘을 로버스트하게 만드는 새로운 오차함수를 제안했으며, 새 방법의 성능을 확인하기 위해 Liano가 제안한 방법에 따라 모의실험을 수행했다. 실험결과 새 방법은 LMS방법만큼 안정적이었으며, Liano의 LMLS방법보다 더 로버스트했다. 또 실제 사례를 분석함으로써 이 방법이 의미있는 방법임을 보였다. 새 방법은 특히 오차가 없거나 작은 오차를 갖는 표본에 대해서도 좋은 성질을 가짐으로서 대형오차의 유무에 관계없이 항상 사용할 수 있는 방법으로 판명되었다.

• Clinical and Experimental Pediatrics
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• v.51 no.8
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• pp.861-867
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• 2008

Purpose : We carried out this study to determine if there is any difference in the occurrence rate of the epileptiform discharge between awake EEG and sleep EEG and if there are any factors influencing on the occurrence rate of EEG. Methods : This study included 178 epileptic children who had visited neurology clinic of the department of pediatrics, Pusan National University Hospital from July 2005 to July 2006. The medical and EEG records of these children who had had both awake EEG and sleep EEG were reviewed. We analysed the occurrence rate of the epileptiform discharge between awake EEG and sleep EEG. We investigated the related clinical factors which included sex, seizure types, underlying causes, age at first seizure, antiepileptic drug (AED) medication, age at recording, and background activity. Results : Among 178 epileptic children, 91 patients (51.1%) showed epileptiform discharge in awake or sleep states, 10 patients (11.0%) abnormal only in awake, 40 patients (44.0%) abnormal only in sleep, 41 patients (45.0%) abnormal in both awake EEG and sleep EEG. The occurrence rate of sleep EEG was 81 of 178 patients (45.5%) which was more than that of the awake EEG (28.7%) (P<0.001). The occurrence rate of sleep EEG is more than that of the awake EEG regardless of sex and underlying causes. But there is no significant difference from awake EEG and sleep EEG in finding the epileptiform discharge in the patient with generalized seizure, younger than 5 years old at first seizure, younger than 10 years old at recording, no antiepileptic medication, and abnormal background activity. Conclusion : The sleep EEG is thought to be more helpful in the diagnosis of childhood epilepsy.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.32 no.9
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• pp.88-93
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• 2004

A method is suggested for validating the existence of bias error on GPS carrier measurement. The baseline constraint is used as an addition measurement, which augments the original measurement equation. The detection probability is calculated on both cases. The first case is using GPS carrier measurement only, the second case is using GPS carrier and a baseline constraint. The improvement of the detection probability is shown, and the advantage of using baseline constraint is described statistically, the results of the simulation is shown and analyzed.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.39C no.11
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• pp.985-993
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• 2014

This paper suggested a new evaluation method for optimal HUD position through a correlation based on between biological signal as and statistical analysis which using (Electroencephalogram, EEG) and ANOVA. This experiment was conducted two kinds of method to evaluate the optimal HUD position. At first, visual stimulus suggested from six different positions(the top and the bottom of the left, the top and the bottom of the center and the top and the bottom of the right on the screen) in laboratory and an object image was shown for 30 seconds in a screen which has $235{\times}197cm2$ size. And second, HUD image was configured from three different positions and an object image was shown for 30 seconds in a screen. EEG, which used ${\alpha}$-wave and ${\beta}$-wave for evaluate an emotional stability, were measured from Fp1, Fp2, F7 and F8 channel based on ten to twenty electrode system. From the result in laboratory, F7 ${\beta}$-wave was shown statistically significant to significance probability of 0.006 and between ${\alpha}$-wave and ${\beta}$-wave were showed a negative correlation(r=-0.190). Also, Both the top of left and the bottom of center were showed lower ${\beta}$-wave than the bottom of right. From the result in railway simulator, Fp1 ${\beta}$-wave was appeared statistically significant as significance probability of 0.033 and it was showed lower ${\beta}$-wave than center. The outcome of this study will be helpful about evaluation of optimal HUD position through correlation between alpha wave and beta wave.