• 한국컴퓨터산업교육학회:학술대회논문집
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• 한국컴퓨터산업교육학회 2003년도 제4회 종합학술대회 논문집
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• pp.87-94
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• 2003

Anisotropic diffusion is a selective smoothing technique that promotes smoothing within a region instead of smoothing across boundaries. In anisotropic diffusion, the rate of smoothing is controlled by the local value of the diffusion coefficient chosen to be a function of the local image gradient magnitude. El-Fallah and Gary E. Ford represented the image as a surface and proved that setting the inhomogeneous diffusion coefficient equal to the inverse of the magnitude of the surface normal results in surface evolving speed that is proportional to the mean curvature of the image surface. This model has the advantage of having the mean curvature diffusion (MCD) render invariant magnitude, thereby preserving structure and locality. In this paper, the proposed MCD model efficiently reduces diffusion coefficient at the thin edges using the smoothness of the surface.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2008년도 춘계학술대회 논문집
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• pp.813-819
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• 2008

For the wear characteristics assessment of Saemaul train passing through curves, an analysis model for multi-car system has been developed. By using this model and ADAMS/Rail, sensitivity analyses have been conducted for the wear characteristics by changing the related parameters. According to the increase of running speed, the wear number, the sliding mean and friction coefficient were increased. At high speed, the wear number, the sliding mean and friction coefficient of left wheel showed higher than right wheel. If the cant increased, the wear number the sliding mean and friction coefficient increased. but decreased based on the balance cant value by the curvature and running speed.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2003년도 춘계학술대회논문집
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• pp.617-621
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• 2003

Existing loudness models are specified only to diotic sounds in spite of the fact that normal human beings hear dichotic sounds. Approximately, the arithmetic mean of loudness values of both ear signals has been suggested for the resultant perceived loudness. In this study, the dependence of overall loudness perception on the interaural level differences was investigated by the subjective tests. It was found that the larger the interaural level difference, the louder the perception than the mean of calculated loudness values at both ears and the lower the critical band rate or the reference level, the louder the perception than the mean value. A modified loudness model was proposed to he applicable to dichotic sounds by using the equivalent diotic levels.

• 치위생과학회지
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• 제24권1호
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• pp.22-28
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• 2024

Background: Particulate matter (PM) has been extensively observed due to its negative association with human health. Previous research revealed the possible negative effect of air pollutant exposure on oral health. However, the predictive model between air pollutant exposure and the prevalence of periodontitis has not been observed yet. Therefore, this study aims to propose a predictive model for the number of patients with periodontitis exposed to PM and atmospheric factors in South Korea using deep learning. Methods: This study is a retrospective cohort study utilizing secondary data from the Korean Statistical Information Service and the Health Insurance Review and Assessment database for air pollution and the number of patients with periodontitis, respectively. Data from 2015 to 2022 were collected and consolidated every month, organized by region. Following data matching and management, the deep neural networks (DNN) model was applied, and the mean absolute percentage error (MAPE) value was calculated to ensure the accuracy of the model. Results: As we evaluated the DNN model with MAPE, the multivariate model of air pollution including exposure to PM_2.5, PM₁₀, and other atmospheric factors predict approximately 85% of the number of patients with periodontitis. The MAPE value ranged from 12.85 to 17.10 (mean±standard deviation=14.12±1.30), indicating a commendable level of accuracy. Conclusion: In this study, the predictive model for the number of patients with periodontitis is developed based on air pollution, including exposure to PM_2.5, PM₁₀, and other atmospheric factors. Additionally, various relevant factors are incorporated into the developed predictive model to elucidate specific causal relationships. It is anticipated that future research will lead to the development of a more accurate model for predicting the number of patients with periodontitis.

• 한국해안·해양공학회논문집
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• 제20권3호
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• pp.321-331
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• 2008

본 연구에서는 경기만과 한강하구 연안에 대하여 물리학적인 특성을 파악하고, 대표적인 인자인 조위에 대한 불확실성을 분석하기 위해 MIKE 21의 HD (HyDrodynamics only)를 이용하였다. 기준 실험을 포함하여 하천유량 4가지, 격자 간격 2가지, 경계조건 4가지 그리고 수심 4가지 등 총 15개의 경우에 대해 실험을 수행하였다. 평균조차의 편차에 대한 RMSD(제곱평균제곱근편차, root mean square deviation)를 추정하였다. RMSD는 영국의 자연환경조사회(NERC, 1975)가 도입한 이래로 수문자료 적합도 분석을 위해 자주 사용되어 왔으며 가장 작은 값이 모형에 적합한 것이다. 평균조차 RMSD가 염하수로에서 0.1148로 가장 크며 연평도에서 0.0400으로 가장 작게 산출되었다. 결과적으로 조석(평균조차)은 외해보다 개발이 집중되는 연안과 하구역에서 불확실성이 큰 것으로 판단 할 수 있다. 또한 원수심을 10% 하향조정한 경우 평균조차 RMSD가 0.1540으로 가장 크게 산출되었으며, RMSD의 비교결과는 격자간격($0.0759{\sim}0.0851$), 경계조건($0.0376{\sim}0.0788$) 및 하천유량배분($0.0318{\sim}0.0471$)보다는 수심($0.0478{\sim}0.1540$)의 영향이 가장 큰 것으로 해석 가능하다.

• 한국멀티미디어학회논문지
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• 제25권10호
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• pp.1448-1456
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• 2022

This paper studies a model to diagnose efficiency reduction of inverter using Multilayer Perceptron(MLP). In this study, two inverter data which started operation at different day was used. A Multilayer Perceptron model was made to predict photovoltaic power data of the latest inverter. As a result of the model's performance test, the Mean Absolute Percentage Error(MAPE) was 4.1034. The verified model was applied to one-year-old and two-year-old data after old inverter starting operation. The predictive power of one-year-old inverter was larger than the observed power by 724.9243 on average. And two-year-old inverter's predictive value was larger than the observed power by 836.4616 on average. The prediction error of two-year-old inverter rose 111.5572 on a year. This error is 0.4% of the total capacity. It was proved that the error is meaningful difference by t-test. The error is predicted value minus actual value. Which means that PV system actually generated less than prediction. Therefore, increasing error is decreasing conversion efficiency of inverter. Finally, conversion efficiency of the inverter decreased by 0.4% over a year using this model.

• 한국산학기술학회논문지
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• 제17권6호
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• pp.656-662
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• 2016

우리는 2001년부터 건설기술정보시스템(Construction Technology Digital Library system, CODIL)을 통해 각종 건설기술관련 원문을 서비스하고 있다. CODIL은 건설기술관련 자료를 데이터베이스로 구축하여 서비스하는 시스템이다. 하지만 매년 DB 확충 요구는 커지고 있으나 이에 필요한 예산은 줄고 있는 실정이다. 따라서 제한된 예산으로 국내 건설기술 원문을 효과적으로 서비스하기 위한 만족도를 조사하였다. 만족도를 계량화된 수치로 표현하기 위해 Tobit 모형을 이용하여 국내 건설기술 원문서비스에 대한 화폐 가치로 추정하였다. Tobit 모형은 비시장재의 가치를 추정하기 위해 사용되는 조건부가치 평가법의 하나로써 편의된 이상치가 지불의사액에 반영되지 않도록 좌변 또는 우변의 한계치를 절삭하여 관측하는 제한종속 변수모형이다. 우리는 312명을 표본대상으로 하여, Tobit 모형을 이용하여 6종의 건설기술관련 원문서비스에 대한 평균, 중앙, 절삭된 지불의사액을 계산하였다. 또한 원문서비스에 대한 지불의사액에 영향을 미치는 통계적으로 유의한 설명변수를 파악하였다. 1건당 원문서비스의 평균가치가 46,530원으로 추정되었다. 본 연구의 의의로는 국내에서 처음으로 건설기술 원문서비스의 가치 추정에 Tobit 모형을 이용하였다.

• 대기
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• 제19권1호
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• pp.93-106
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• 2009

Analysis has been made on the wind wave characteristics in terms of significant wave height ($H_s$) near the Korean marginal seas in the 2006 - 2007 year using the third generation wave model, WAVEWATCH - III model. In order to evaluate its performance, its results were compared with the observed data using KMA ocean buoy. The two year average RMSE between modeled and observed Hs shows reasonably small value of about 0.37 m. The accuracy of predicted values in the year 2007 is increased mainly due to finer model grid size and better accurate wind field. The model used in this study predicts very well the characteristics ($H_s$) of wind waves near the Korean Peninsular. Simulated monthly wind waves show the evident seasonal variations due to Typhoons in summer season. When Typhoons approach to Korean Peninsular, the accuracy of wind waves predictions is lower than that of annual mean value.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1997년도 추계학술대회 논문집
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• pp.450-453
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• 1997

There are many studies about optimization using genetic algorithm and desirability function. It's very important to find the optimal value of something like response surface or regression model. In this study I ind~cate the problem using the old type desirability function, and suggest the new type desirabhty functton that can fix the problem better, and simulate the model. Then I'll suggest the form of desirability function to find the optimum value of response surfaces which are made by mean and standard deviation using genetic algorithm and new type desirability function.

• 디지털산업정보학회논문지
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• 제7권2호
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• pp.1-8
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• 2011

In this study, software products developed in the course of testing, software managers in the process of testing software test and test tools for effective learning effects perspective has been studied using the NHPP software. The finite failure non-homogeneous Poisson process models presented and the life distribution applied extreme distribution which used to find the minimum (or the maximum) of a number of samples of various distributions. Software error detection techniques known in advance, but influencing factors for considering the errors found automatically and learning factors, by prior experience, to find precisely the error factor setting up the testing manager are presented comparing the problem. As a result, the learning factor is greater than automatic error that is generally efficient model could be confirmed. This paper, a numerical example of applying using time between failures and parameter estimation using maximum likelihood estimation method, after the efficiency of the data through trend analysis model selection were efficient using the mean square error.