• 한국수자원학회:학술대회논문집
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• 한국수자원학회 2022년도 학술발표회
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• pp.141-141
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• 2022

Drought is a global phenomenon that affects almost all landscapes and causes major damages. Due to non-linear nature of contributing factors, drought occurrence and its severity is characterized as stochastic in nature. Early warning of impending drought can aid in the development of drought mitigation strategies and measures. Thus, drought forecasting is crucial in the planning and management of water resource systems. The primary objective of this study is to make improvement is existing drought forecasting techniques. Therefore, we proposed an improved version of Seasonal Autoregressive Integrated Moving Average (SARIMA) model (MD-SARIMA) for reliable drought forecasting with three years lead time. In this study, we selected four watersheds of Han River basin in South Korea to validate the performance of MD-SARIMA model. The meteorological data from 8 rain gauge stations were collected for the period 1973-2016 and converted into watershed scale using Thiessen's polygon method. The Standardized Precipitation Index (SPI) was employed to represent the meteorological drought at seasonal (3-month) time scale. The performance of MD-SARIMA model was compared with existing models such as Seasonal Naive Bayes (SNB) model, Exponential Smoothing (ES) model, Trigonometric seasonality, Box-Cox transformation, ARMA errors, Trend and Seasonal components (TBATS) model, and SARIMA model. The results showed that all the models were able to forecast drought, but the performance of MD-SARIMA was robust then other statistical models with Wilmott Index (WI) = 0.86, Mean Absolute Error (MAE) = 0.66, and Root mean square error (RMSE) = 0.80 for 36 months lead time forecast. The outcomes of this study indicated that the MD-SARIMA model can be utilized for drought forecasting.

• 한국학교수학회논문집
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• 제11권3호
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• pp.363-376
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• 2008

본 논문의 목적은 창의적 능력의 한 요소로 간주되어 온 직관에 관한 이해와 관심을 새롭게 하고, 수학 교수 학습에서 직관의 가치를 제고하기 위한 것이다. 이를 위하여 문헌 고찰을 통해 직관의 본질과 직관에 관한 연구의 역사, 사고의 발현 과정을 선형적인 측면에서 몇 개의 단계로 나누어 분석하는 정보치리 접근 방법에 의한 직관 연구를 살펴보았다. 오래 전부터 직관은 신비스러운 속성을 지닌 대상으로 간주되었고, 따라서 직관을 탐구하기 위한 논의 자제가 어려됐다. 그렇지만 20세기에 들어와 심리학 관점에서 직관에 대한 논의가 활발히 이루어지고 있다. 직관에 대한 연구는 역사정보처리 관점에 의한 직관 연구가 주를 이루었으나, 최근에는 병렬분산처리 모델 관점에 의한 직관 연구도 이루어지고 있다. 그렇지만 직관에 관한 연구들은 직관의 속성을 완벽하게 규명하기는 어렵다는 것을 말해 준다. 한편 수학교육 분야에서 직관에 관한 연구는 몇 및 학자에 의해 수행되었지만, 수학 교수 학습 상황과 관련하여 실천적이고 체계적인 연구는 미약한 상황이다. 따라서 직관 탐구의 역사에 대한 시사점을 바탕으로 수학교육에서 직관 탐구의 의미와 직관을 중심으로 한 수학 교수 학습에 대한 시사점을 제시하였다.

• 지능정보연구
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• 제20권1호
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• pp.15-34
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• 2014

성과 지표로서의 전방적 정확도는 정답인 경우 1, 오답인 경우 0으로 계사하는 이른바 모듈화된 정확도를 충분히 고려하지 못한다. 이에 문제의 특징에 따라 모듈화 정확도에 맞는 판별 규칙을 최적화 하는 보다 스마트한 판별 알고리즘이 필요하다고 볼 수 있다. 이에 따라, 스마트한 알고리즘은 문제 유형에 따라 보다 일반화되고 실제 성능의 왜곡을 야기할 수 있는 이산화에 제약되지 않아야 한다. 따라서 본 논문의 목적인 모듈화 정확도를 개선하는 새로운 부스팅 알고리즘을 제안하는 것이다. 이에 일반화를 도모하고 문제 영역의 특성에 맞게 판별화 모형을 선정하기 위해 스마트함을 고려한 모형 선정 알고리즘을 개발하였다. 제안된 방법의 성능을 검증하기 위해 실제로 47,000여건의 특허건을 가지고 실제 실용화 가능성을 판별하는 실험을 수행하였다.

• 비교문화연구
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• 제33권
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• pp.143-169
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• 2013

Recently, because of the danger and damages that following the steady development of scientific technologies, natural science is faced with many humane and ethical problems. So it is asserted the interdisciplinary with social and human science. However, it comes commonly that the ethical issues such as world view and one's view of life caused the development of sociology, especially development of the market economy. But in many cases, the interdisciplinary can be useful for widen the view of scholars. The interdisciplinary is actually connected with the problems of philosophy, and located in that domain. In this case, this is noticed as a model to the philosophers in 18th century, especially Denis Diderot. Diderot published De $l^{\prime}interpr{\acute{e}}tation$ de la nature during editing the Encyclopedia, from there he picked out the contents from piles of documents of Encyclopedia. Even though the contents or opinions of De $l^{\prime}interpr{\acute{e}}tation$ de la nature are inaccuracy or erroneous, it shows that how human-social science and natural science encountered. Diderot studied mathematics and then Diderot accepted to the natural science proposal, he approaches philosophy with translate English books to the French. Next he understood natural science by reading Buffon and Maupertuis, and during working for Encyclopedia, he possessed his knowledge that he can claim his opinion to other scholars. However in this De $l^{\prime}interpr{\acute{e}}tation$ de la nature, Diderot who sometimes rebutted other scholars' theory and demonstration, tried to build a philosophy on metaphysics in order to it was important for himself that he imposed the methods of science and importance of experience. Anyhow, this De $l^{\prime}interpr{\acute{e}}tation$ de la nature cause consider the recognition of Diderot in the field of natural science, and is suggested as a model about his Nature. This mean that it is an expression of his philosophy, and the content is found from natural philosophy and empirical philosophy. Like giving these attache the importance of method study for science and technique, these are targeted the promotion of popularization of natural-science and scientific-technology. Also it advocates fulfilling from reasonable philosophy to empirical philosophy. Therefore, the philosophy which was speculative and abstracted became his philosophy which was writing the meaning, as waiting the discovery of science. And at that time, the humanities made interdisciplinary with natural science.

• 대한토목학회논문집
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• 제14권4호
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• pp.867-874
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• 1994

유량이 매우 작은 갈수기(渴水期)에 자연하천으로 방류된 비보존성 오염물질의 이동 및 화학적, 생화학적 변환과정의 복잡성을 구명하기 위해서 이송, 확산, 변환 그리고 하천수로에 존재하는 저장대(貯藏帶)에서 오염물질의 저장 및 교환과정을 규정하는 한 쌍의 방정식으로 이루어진 수학적 모형을 개발하고 이의 해를 수치해석적인 방법에 의해 구하였다. "저장-변환 모형"이라 명명된 본 수화적 모형은 갈수기(渴水期) 하천에서의 비보존성 오염물질의 혼합 및 변환 메카니즘의 비정규분포적인 특성을 보다 정확하게 예측할 수 있도록 개발되었다. 모형의 모의결과, 농도-시간곡선의 전체적인 형태, 첨두농도, 그리고 첨두농도에 도달하는 시간 등에 있어서 저장-변환 모형이 종래의 1차원 확산모형보다 실측자료에 더욱 정확하게 일치한다는 사실이 밝혀졌다. 본 연구에서 개발된 저장-변환 모형은 웅덩이-급여울 연속구조로 이루어진 하천에서의 오염물질의 이동 및 변환거동을 예측하는 모형으로서 1차원 확산모형에 비해 월등히 개선된 모형으로 밝혀졌다.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1993년도 한국자동제어학술회의논문집(국내학술편); Seoul National University, Seoul; 20-22 Oct. 1993
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• pp.742-748
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• 1993

The dynamics and control of two complex column configurations (sidestream column with stripper; prcfractionater/sidestream column configuration), which are multivariable interacting and nonlinear, have been studied. A new control scheme developed by Hanand Park(1993) to deal with the nonlinear and multivariable nature of distillation processes has been applied to these complex distillation configurations. The control scheme incorporates a nonlinear wave model into a generic model control framework. An observer based on the nonlinear wave model is used to determine the profile positions of distillation column sections. The control scheme enables tight control of the profile position of each column section that leads to fast stabilization of product compositions.

• 전자공학회논문지A
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• 제33A권7호
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• pp.162-170
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• 1996

A breakdown model of gate oxides under constant current stresses is proposed. This model directly relates the oxide lifetime to the stress current density, and includes statistical nature of oxide breakdown using the concept of "effective oxide thinning". It is shown tha this model can reliably predict the TDDB characteristics for any current stress levels and oxide areas.

• Journal of the Korean Statistical Society
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• 제25권3호
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• pp.359-368
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• 1996

The maximum likelihood estimation is discussed for the NLAR model with Laplacian marginals. Since the explicit form of the estimates cannot be obtained due to the complicated nature of the likelihood function we utilize the automatic computer optimization subroutine using a direct search complex algorithm. The conditional least square estimates are used as initial estimates in maximum likelihood procedures. The results of a simulation study for the maximum likelihood estimates of the NLAR(1) and the NLAR(2) models are presented.

• 한국시뮬레이션학회논문지
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• 제4권1호
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• pp.113-119
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• 1995

In 3D computer graphics, fractal techniques have been applied to terrain models. Even though fractal models have become popular for recreating a wide variety of the shapes found in nature, a specific 3D terrain model such as Uleung Island could not be formulated by statistical fractals easily owing to the random effects. However, by locating the midpoints on the edges and the surface of a specific terrain such as Uleung Island, a similar shape of the terrain model can be simulated. This paper shows the way of simulating 3D Uleung Island terrain model by the statistical fractals wherein the subdivision algorithm is used.

• 산업공학
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• 제11권3호
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• pp.89-101
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• 1998

The randomness of the input variables in simulation experiments produce output responses which are also realizations of random variables. The random responses make necessary the use of statistical inferences to adequately describe the stochastic nature of the output. The analysis of the simulation output of non-terminating simulations is frequently complicated by the autocorrelation of the output data and the effect of the initial conditions that produces biased estimates. The regenerative method has been developed to deal with some of the problems created by the random nature of the simulation experiments. It provides a simple solution to some tactical problems and can produce valid statistical results. However, not all processes can he modeled using the regenerative method. Other processes modeled as regenerative may not return to a given demarcating state frequently enough to allow for adequate statistical analysis. This paper shows how the state transformation concept was successfully used in a queueing model and a job shop model. Although the first example can be analyzed using the regenerative method. it has the problem of too few recurrences under certain conditions. The second model has the problem of no recurrences. In both cases, the state transformation increase the frequency of the demarcating state. It was shown that time state transformations are regenerative and produce more cycles than the best typical discrete demarcating state in a given run length.