• Title/Summary/Keyword: T-변수

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A Modified Horvitz-Thompson Estimator by Transformation of Variables (변수변환에 의한 수정 HORVITZ-THOMPSON 추정량)

  • 류제복
    • The Korean Journal of Applied Statistics
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    • v.17 no.1
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    • pp.27-34
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    • 2004
  • The Horvitz-Thompson(H-T) estimator is less efficient than PPS estimators in some cases. We use the two-stage variable transformation in order to remove the drawbacks and increase the efficiency of H-T estimator. We transform the auxiliary variable to use the Midzuno-Sen sampling scheme at the first stage. And the next stage, we also transform the study variable to reduce the variance of H-T estimator using the inclusion probability obtained from the first transformation. We compare the efficiency between a suggested modified H-T estimator and PPS estimators.

Predictions of dam inflow on Han-river basin using LSTM (LSTM을 이용한 한강유역 댐유입량 예측)

  • Kim, Jongho;Tran, Trung Duc
    • Proceedings of the Korea Water Resources Association Conference
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    • 2020.06a
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    • pp.319-319
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    • 2020
  • 최근 데이터 과학의 획기적인 발전 덕분에 딥러닝 (Deep Learning) 알고리즘이 개발되어 다양한 분야에 널리 적용되고 있다. 본 연구에서는 인공신경망 중 하나인 LSTM(Long-Short Term Memory) 네트워크를 사용하여 댐 유입량을 예측하였다. 구체적인 내용으로, (1) LSTM에 필요한 입력 데이터를 효율적으로 사전 처리하는 방법, (2) LSTM의 하이퍼 매개변수를 결정하는 방법 및 (3) 다양한 손실 함수(Loss function)를 선택하고 그 영향을 평가하는 방법 등을 다루었다. 제안된 LSTM 모델은 강우량(R), 댐유입량(Q) 기온(T), 기저유량(BF) 등을 포함한 다양한 입력 변수들의 함수로 가정하였으며, CCF(Cross Correlations), ACF(Autocorrelations) 및 PACF(Partial Autocorrelations) 등의 기법을 사용하여 입력 변수를 결정하였다. 다양한 sequence length를 갖는 (즉 t, t-1, … t-n의 시간 지연을 갖는) 입력 변수를 적용하여 데이터 학습에 최적의 시퀀스 길이를 결정하였다. LSTM 네트워크 모델을 적용하여 2014년부터 2020년까지 한강 유역 9개의 댐 유입량을 추정하였다. 본 연구로부터 댐 유입량을 예측하는 것은 홍수 및 가뭄 통제를 위한 필수 요건들 중 하나이며 수자원 계획 및 관리에 도움이 될 것이다.

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A Study on the Parameters of WASP5 Model in Daechung Reservoir (대청호에서 WASP5 모델 매개변수에 관한 연구)

  • Han, Woon Woo;Kim, Kyu-Hyung;Ahn, Tae-Bong
    • Journal of the Korean GEO-environmental Society
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    • v.4 no.3
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    • pp.69-77
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    • 2003
  • This study was carried out to evaluate the WASP5 model parameters and to analyze the sensitivity of parameters in Daechung Reservoir. The values predicted by the model and tendency were very similar to the observed data at Daejeon intake, so it is possible to predict water quality of the Daejeon intake region in the future. Results from the sensitivity analysis showed that Chlorophyll-a was sensitive to variations in saturated growth rate of phytoplankton, endogenous respiration rate of phytoplankton, extinction coefficient and temperature. T-N was sensitive to mineralization rate of dissolved organic nitrogen and temperature. T-P was affected by T-P load, temperature, extinction coefficient, mineralization rate of dissolved organic phosphorus and saturated growth rate of phytoplankton. BOD was influenced by deoxygenation rate and temperature, and DO was influenced by temperature. Adequate input data was applied and assessed through the model sensitivity analysis. So it is possible to distinguish the input data which need careful attention when it has application to model.

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Local Separation Principle of Fuzzy Observer-Controller (퍼지 관측기-제어기의 국소적 독립 원리)

  • Lee, Ho-Jae;Park, Jin-Bae;Joo, Young-Hoon
    • Journal of the Korean Institute of Intelligent Systems
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    • v.14 no.7
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    • pp.902-906
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    • 2004
  • A separation principle of the Takagj-Sugeno (T-S) fuzzy-model-based observer-control is investigated. When the premise variables are able to be measured or directly computed from the outputs of the T-S fuzzy system and the fuzzy inference rules for the plant, control, and observer share the premise parts, the T-S fuzzy-model-based observer and the T-S fuzzy-model-based control can be separately designed such that the global stabilizability is guaranteed by the fuzzy observer-based output-feedback control. In this case, the global separation principle is well established. On the other hand, when the premise variables are unmeasurable or cannot be computed from the outputs, they should also be estimated. We examine the separation principle of this case. If the decay rates of the T-S fuzzy-model-based control and observer are sufficiently fast, the global separation is assured. Otherwise we show that the separation principle holds locally.

A Study on the Teaching-Learning of Parameter Concept (매개변수 개념의 교수-학습에 관한 연구)

  • 김남희
    • Journal of Educational Research in Mathematics
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    • v.14 no.3
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    • pp.305-325
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    • 2004
  • This study is on the teaching-learning of parameter concept in secondary school mathematics. In our school mathematics curriculum, parameter concept is explicitly presented at high school mathematics textbook. But student have difficulty in understanding parameter concept because this concept is implicitly used in the textbook from 7-grade mathematics. Moreover, it is true that mathematics teacher give a little attention to student's understanding of parameter con- cept. In this study, we analyzed concept definition of parameter and the extension of parameter on the basis of preceding research, our mathematical curriculum, mathematical dictionaries. After that, we concluded that parameter is explicitly called in t where x= f(t), y= g(t) and parameter is implicitly treated in the learning of relation between quantities in our mathematical curriculum. We pointed to the importance of parameter concept in the successful learning of school algebra. Specially, when the level of algebra is in the learning of relation between quantities, parameter is the key concept for understanding and representing of families of equations or functions. In mathematics class, students have opportunity to reflect that what the role of each variable(parameter, dependent variable, independent variable etc.) is, and where the information which determines it comes from. It is for mathematical communications as well as learning school algebra. Therefore, mathematics teacher's didactical attention is more needed to student have a good concept image of parameter before they learn explicitly its concept definition.

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The Parametrization and Structure Analysis for a Perspective Silhouette of a Canal Surface (Canal 곡면의 투시 윤곽곡선의 매개변수화 및 구조 분석)

  • Kim, Ku-Jin;Lee, In-Kwon
    • Journal of the Korea Computer Graphics Society
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    • v.7 no.3
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    • pp.1-7
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    • 2001
  • We present an efficient and robust algorithm to parametrize a perspective silhouette curve of a canal surface. We also detect each connected component of the silhouette. A canal surface is an envelope surface of a moving sphere with varying radii, which is defined by the center trajectory C(t) and radius function r(t) of the moving sphere. A canal surface can be decomposed to a set of characteristic circles. We derive the equations for the silhouette points on each characteristic circle, then parameterize the silhouette curve by using the equation. The sphere $S(t_*)$ with center point $C(t_*)$ and radius $r(t_*)$ intersects with the canal surface at a characteristic circle $K(t_*)$. The perspective silhouette of the sphere $S(t_*)$ from given view point consists of a circle $Q(t_*)$. By finding the values of t at which K(t) and Q(t) tangentially intersect, we detect each connected component of the silhouette curve.

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The Function Construction based on Modular Design Technique (모듈러 설계기법에 기초한 함수구성)

  • Park, Chun-Myoung
    • Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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    • 2012.10a
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    • pp.918-919
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    • 2012
  • This paper present a method of function decomposition and input variable manipulation method based on modular design techniques. We obtain the column multiplicity of decomposition function according to row decomposition method. Also, the proposed partial decomposition function have advantage which is able to omit control function using t-Gate. We find the advantage for internal connection decrement 12% and T-gate number 16%, therefore we find the simple design circuit.

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A Study on Factors Affecting the Intention of Using IoT-Based Fitness Tracker (IoT기반 피트니스 트래커의 사용의도에 영향을 미치는 요인에 관한 연구)

  • Cho, Dug Yun;Han, Kyeong Seok
    • Journal of Digital Contents Society
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    • v.19 no.9
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    • pp.1717-1726
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    • 2018
  • This study is for looking into Factors affecting the Intention of using about Fitness Tracker based on IoT by Flow Theory and UTAUT Model. The independent variables of the IoT-based fitness tracker have been selected as Challenge, Skill Factors used in the Flow experience theory and selected the personal characteristics of health perception, enjoyment, Social Influence, and Facilitating Conditions. In addition UTAUT theory was used as parameter of Performance Expectancy and Effort Expectancy and intention of Use behavior was selected as a dependent variable. For verifying research hypothesis, This study collected 126 surveys data and carried out a statistical analysis by Smart PLS. The result shows that new Flow Experience and Personal Characteristic Factors with key variables in the UTAUT Model affect significantly to Intention of using about Fitness Wearable environment based IoT.

The Relational Role of Customer Participation in Interaction Process (상호작용과정에서 고객참여의 관계적 역할)

  • Ahn, Jinwoo;Oh, Hyung Jun
    • Management & Information Systems Review
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    • v.39 no.3
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    • pp.37-51
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    • 2020
  • Customer participation in the service encounter plays an important role in the interaction process. In addition, customer participation is affecting the development of relationships between customer-service provider. Previous researches revealed the role of customer participation through a fragmented and cross-sectional approach, however, given the dynamics of the relationship, it is necessary to identify the role of customer participation from a longitudinal perspective. In addition, it is necessary to determine the cause of the overlap between the antecedent variables and consequent variables. This study aims to identify the relational role of customer participation by clarifying how customer participation affects relationship development from a longitudinal perspective, focusing on trust and commitment variables which are keys to relationship marketing. The related role of customer participation is analyzed through a regression analysis through long-term data. The results of the study showed that commitment(t1) directly had a positive effect on customer participation. However, trust(t1) has been shown to have a direct positive effect on the sub-dimensions of customer participation, such as personal interaction and responsible behavior. Customer participation(t2) affected by this trust(t1) and commitment(t1) again turned out to have a positive effect on trust(t3) and commitment(t3). In conclusion, although customer participation is affected by the relational variables, it can be seen that customer participation is a major factor that can improve the relational variables again through the interaction process. For this reason, a service firm can seek to develop relationships with customers by drawing and utilizing their needs to exchange information and to interact in the service encounter.

Study on the Prediction of short-term Algal Bloom in Juksan weir Using the Model Tree (모델트리를 활용한 죽산보 단기조류예측에 관한 연구)

  • Lee, Bo-Mi;Yi, Hye-Suk;Chong, Sun-A;Joo, Yong-Eun;Kim, Ho-Joon;Choi, Kwang-Soon
    • Proceedings of the Korea Water Resources Association Conference
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    • 2018.05a
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    • pp.450-450
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    • 2018
  • 최근 기후변화와 수온상승으로 인한 녹조발생이 빈번하게 나타나며, 녹조발생에 관한 관심은 꾸준히 증가하고 있는 추세이다. 본 연구는 효율적인 녹조관리를 위하여 모델트리를 활용하여 클로로필-a 단기조류예측 기법을 개발하였다. 대상지역으로 영산강수계의 죽산보를 선정하였으며, 2013년 1월부터 2016년 12월까지 나주 수질자동측정망의 일 단위자료와 동일기간 광주 기상청의 일별 기상자료를 이용하였다. 상관 분석을 통해 T-N, T-P, N/Pratio와 클로로필-a, 수온, 일사량, 강수량을 독립변수로, 단기(t+1일, t+3일, t+5일, t+7일) 클로로필-a를 종속변수로 선정하여 단기조류예측기법을 개발하였다. 수집한 자료의 데이터세트는 격일 간격으로 Training, Testing 기간으로 구분하여 적용한 결과, 상관계수는 1일 예측 시, Training 기간에 0.89, Testing 기간에 0.91, 3일 예측 시, Training 기간에 0.74, Testing 기간에 0.68, 5일 예측 시, Training 기간에 0.70, Testing 기간에 0.66, 7일 예측 시, Training 기간에 0.63, Testing 기간에 0.62로 나타났다. RMSE(Root Mean Square Error)는 1일 예측 시, Training 기간에 13.96, Testing 기간에 12.22, 3일 예측 시, Training 기간에 20.03, Testing 기간에 22.14, 5일 예측 시, Training 기간에 21.32, Testing 기간에 22.57, 7일 예측 시, Training 기간에 23.52, Testing 기간에 23.45로 나타났다. 예측주기에 따라 모델트리와 회귀식에서 활용한 독립변수는 1일 예측 시, 모델트리는 N/Pratio, 클로로필-a, 회귀식은 클로로필-a로 다르게 나타났다. 반면, 3일, 5일, 7일 예측 시, 모델트리와 회귀식에 활용된 변수는 같게 나타났다. 클로로필-a, 수온, 일사량은 5일 예측 시 활용된 변수로, 3일 예측 시에는 기상항목인 강수량이, 7일 예측 시에는 수질항목인 T-N, N/Pratio가 추가되었다. 특히 1일 예측 시 일 때, 높은 예측정도와 활용된 변수의 수가 적게 나타나는 것을 확인하였으며, 예측기간이 길어질수록 예측의 정확성이 낮아지고, 활용된 변수의 수가 많아지는 것을 확인하였다. 향후 적정한 예측기간을 판단하고 예측가능성을 높이기 위해서는 지속적인 자료취득 및 개선이 필요하며, 이를 바탕으로 적절한 단기조류예측이 가능할 것으로 판단된다.

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