• 한국수자원학회논문집
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• 제46권11호
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• pp.1053-1067
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• 2013

본 논문에서 소개되는 분포형 생태수문모형은 현실적으로 확보 가능한 입력자료와 최소한의 매개변수를 이용하여 유역의 수문, 식생, 지표온도를 모의하는 모형이다. 개발된 모형은 내성천 유역에 대해 적용하여 모형의 활용가능성을 살펴보았다. 우선적으로 매개변수에 대해 민감도 분석을 실시하여 모의결과에 많은 영향을 주는 매개변수를 선별해보았으며 이후 최적화 기법을 통해 모형의 매개변수를 추정하여 내성천 유역의 최근 10년간(2001~2010)의 수문, 식생, 지표온도 그리고 추적(routing)을 통한 하천유량 및 하천수온을 모의하였다. 최적화 기법을 통해 추정자료를 이용하여 매개변수를 추정하였으며 일부 격자를 제외한 대다수의 격자에서 적절히 모의된 것을 확인하였다. 하천유량 및 하천수온의 경우 단위 유역 말단 두 지점에 대해 검증을 실시하였으며 하천유량 및 하천수온 적절히 모의된 것을 확인할 수 있었다. 실제 유역인 내성천 유역을 대상으로 분포형 생태수문모형이 최소한(현실적으로 확보 가능한)의 입력자료와 매개변수를 이용함에도 불구하고 유역 수문순환 및 식생을 적절히 설명하고 있음을 살펴볼 수 있다.

• 한국수자원학회논문집
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• 제38권9호
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• pp.699-711
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• 2005

미국 지질조사국(U.S Geological Survey)의 강우-유출모형 DR3M-II(Distributed Routing Rainfall-Runoff Model)를 이용해 도시배수유역의 유출해석을 수행하였다. DR3M-II는 강우사상을 입력자료로 하여 수지상의 관거 또는 자연수로망으로 구성된 도시유역에서의 유출추적을 위해 개발된 모형이다. 대상유역인 산본신도시에서의 실측유출자료를 이용한 모형의 검정 및 검증을 수행하였으며, Rosenbrock기법을 이용해 최적매개변수를 유도하였다. 검증결과 첨두유출량의 평균오차는 $7.4\%$로 상당히 양호한 결과를 보여주었다. 매개변수에 대한 민감도 분석결과 비교적 작은 강우강도의 비가 내릴 경우는 유효 불투수지역의 면적이 첨두유출량이나 유출체적에 가장 민감한 영향을 미치는 인자였으나, 큰 강우강도에서는 조도계수와 유역경사를 정의하는 운동파방정식의 계수 ${\alpha}$가 가장 민감한 영향을 미치는 인자인 것으로 나타났다. 대체적으로 첨두유출량보다는 유출체적이 침투능이나 토양함수조건을 정의하는 매개변수에 보다 민감한 반응을 보였으며, 매개변수 ${\alpha}$는 첨두유출량에 보다 민감한 영향을 미치는 것으로 나타났다.

• Asian-Australasian Journal of Animal Sciences
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• 제18권8호
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• pp.1088-1097
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• 2005

Main objectives of this study were to investigate accuracy, bias and power of linear and threshold model segregation analysis methods for detection of major genes in categorical traits in farm animals. Maximum Likelihood Linear Model (MLLM), Bayesian Linear Model (BALM) and Bayesian Threshold Model (BATM) were applied to simulated data on normal, categorical and binary scales as well as to disease data in pigs. Simulated data on the underlying normally distributed liability (NDL) were used to create categorical and binary data. MLLM method was applied to data on all scales (Normal, categorical and binary) and BATM method was developed and applied only to binary data. The MLLM analyses underestimated parameters for binary as well as categorical traits compared to normal traits; with the bias being very severe for binary traits. The accuracy of major gene and polygene parameter estimates was also very low for binary data compared with those for categorical data; the later gave results similar to normal data. When disease incidence (on binary scale) is close to 50%, segregation analysis has more accuracy and lesser bias, compared to diseases with rare incidences. NDL data were always better than categorical data. Under the MLLM method, the test statistics for categorical and binary data were consistently unusually very high (while the opposite is expected due to loss of information in categorical data), indicating high false discovery rates of major genes if linear models are applied to categorical traits. With Bayesian segregation analysis, 95% highest probability density regions of major gene variances were checked if they included the value of zero (boundary parameter); by nature of this difference between likelihood and Bayesian approaches, the Bayesian methods are likely to be more reliable for categorical data. The BATM segregation analysis of binary data also showed a significant advantage over MLLM in terms of higher accuracy. Based on the results, threshold models are recommended when the trait distributions are discontinuous. Further, segregation analysis could be used in an initial scan of the data for evidence of major genes before embarking on molecular genome mapping.

• 한국농공학회논문집
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• 제58권4호
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• pp.57-66
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• 2016

Harmonized World Soil Database (HWSD) including the global soil information has been implemented to the runoff analysis in many watersheds of the world. However, its accuracy can be a critical issue in the modeling because of the limitation the low resolution reflecting the physical properties of soil in a watershed. Accordingly, this study attempted to assess the effect of HWSD in modeling by comparing parameters of the rainfall-runoff model using HWSD with the detailed soil map. For this, Grid based Rainfall-runoff Model (GRM) was employed in the Hyangseok watershed. The results showed that both of two soil maps in the rainfall-runoff model are able to well capture the observed runoff. However, compared with the detailed soil map, HWSD produced more uncertainty in the GRM parameters related to soil depth and hydraulic conductivity during the calibrations than the detailed soil map. Therefore, the uncertainty from the limited information on soil texture in HWSD should be considered for better calibration of a rainfall-runoff model.

• 한국인공지능학회지
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• 제12권1호
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• pp.17-24
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• 2024

This paper introduces a novel approach to time-series estimation for energy load forecasting within Virtual Power Plant (VPP) systems, leveraging advanced artificial intelligence (AI) algorithms, namely Long Short-Term Memory (LSTM) and Seasonal Autoregressive Integrated Moving Average (SARIMA). Virtual power plants, which integrate diverse microgrids managed by Energy Management Systems (EMS), require precise forecasting techniques to balance energy supply and demand efficiently. The paper introduces a hybrid-method forecasting model combining a parametric-based statistical technique and an AI algorithm. The LSTM algorithm is particularly employed to discern pattern correlations over fixed intervals, crucial for predicting accurate future energy loads. SARIMA is applied to generate time-series forecasts, accounting for non-stationary and seasonal variations. The forecasting model incorporates a broad spectrum of distributed energy resources, including renewable energy sources and conventional power plants. Data spanning a decade, sourced from the Korea Power Exchange (KPX) Electrical Power Statistical Information System (EPSIS), were utilized to validate the model. The proposed hybrid LSTM-SARIMA model with parameter sets (1, 1, 1, 12) and (2, 1, 1, 12) demonstrated a high fidelity to the actual observed data. Thus, it is concluded that the optimized system notably surpasses traditional forecasting methods, indicating that this model offers a viable solution for EMS to enhance short-term load forecasting.

• 한국지능시스템학회논문지
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• 제9권6호
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• pp.627-633
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• 1999

본 논문에서는 면역 시스템에 기반한 자율분산로봇 시스템의 협조 제어 및 군행동 전략의 결정 방법을 제안한다. 면역 시스템은 생체의 자기보호 및 유지시스템이다. 면역 시스템의 유용한 성질은 동적으로 변하는 환경에서 최적의 군행동을 결정하는 문제에 적용 가능하다. 면역 시스템을 자율분산로봇 시스템에 적용하기 위하여 로봇은 B-세포로 환경조건은 항원으로 행동 전략은 항체로 제어파라미터는 T-세포로 각각 모델링 하였다, 환경(항원)변화가 감지되면 각 로봇은 적절한 행동전략(항체)을취한다. 이행동전략은 다른 로봇과의 통신에 의하여 자극 또는 억제을 받는다.(면역 네트워크) 최정적으로 많은 자극을 받은 전략이 군행동 전략으로 채택된다. 이 제어방법은 클론선택과 면역네트워크 가설에 기반을 둔것으로서 최적의 군행동 전략을 결정하는데 이용된다. 또한 제어 파라미터로서 T-세포 모델을 추가함으로서 동적인 환경에서 로봇의 적응능력이 향상되었다.

• Journal of Communications and Networks
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• 제14권2호
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• pp.188-194
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• 2012

Cognitive networks (CNs) are capable of enabling dynamic spectrum allocation, and thus constitute a promising technology for future wireless communication. Whereas, the implementation of CN will lead to the requirement of an increased energy-arrival rate, which is a significant parameter in energy harvesting design of a cognitive user (CU) device. A well-designed spectrum-sensing scheme will lower the energy-arrival rate that is required and enable CNs to self-sustain, which will also help alleviate global warming. In this paper, spectrum sensing in a multi-user cognitive ad hoc network with a wide-band spectrum is considered. Based on the prospective spectrum sensing, we classify CN operation into two modes: Distributed and centralized. In a distributed network, each CU conducts spectrum sensing for its own data transmission, while in a centralized network, there is only one cognitive cluster header which performs spectrum sensing and broadcasts its sensing results to other CUs. Thus, a wide-band spectrum that is divided into multiple sub-channels can be sensed simultaneously in a distributed manner or sequentially in a centralized manner. We consider the energy consumption for spectrum sensing only of an analog-to-digital convertor (ADC). By formulating energy consumption for spectrum sensing in terms of the sub-channel sampling rate and whole-band sensing time, the sampling rate and whole-band sensing time that are optimal for minimizing the total energy consumption within sensing reliability constraints are obtained. A power dissipation model of an ADC, which plays an important role in formulating the energy efficiency problem, is presented. Using AD9051 as an ADC example, our numerical results show that the optimal sensing parameters will achieve a reduction in the energy-arrival rate of up to 97.7% and 50% in a distributed and a centralized network, respectively, when comparing the optimal and worst-case energy consumption for given system settings.

• 한국농공학회논문집
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• 제54권4호
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• pp.1-8
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• 2012

This study is to assess the reduction of non-point source pollution loads for rice straw surface covering of upland crop cultivation at a watershed scale. For Byulmi-cheon watershed ($1.21km^2$) located in the upstream of Gyeongancheon, the HSPF (Hydrological Simulation Program-Fortran), a physically based distributed hydrological model was applied. Before evaluation, the model was calibrated and validated using 9 rainfall events. The Nash-Sutcliffe model efficiency (NSE) for streamflow was 0.62~0.78 and the NSE for water quality (Sediment, T-N, and T-P) were 0.68, 0.60, and 0.58 respectively. From the field experiment of 16 rainfall events, the rice straw covering reduced surface runoff average 10 % compared to normal surface condition. By handling infiltration parameter (INFILT) in the model, the value of 16.0 mm/hr was found to reduce about 10 % reduction of surface runoff. For this condition, the reduction effect of Sediment, T-N, and T-P loads were 87.2, 28.5, and 85.1 % respectively. The rice straw surface covering was effective for removing surface runoff dependent loads such as Sediment and T-P.

• Steel and Composite Structures
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• 제36권3호
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• pp.293-305
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• 2020

This article presented a nanoscale modified continuum model to investigate the free vibration of functionally graded (FG) porous nanobeam by using finite element method. The main novelty of this manuscript is presenting effects of four different porosity models on vibration behaviors of nonlocal nanobeam structure including size effect, that not be discussed before The proposed porosity models are, uniform porosity distribution, symmetric with mid-plane, bottom surface distribution and top surface distribution. The nano-scale effect is included in modified model by using the differential nonlocal continuum theory of Eringen that adding the length scale into the constitutive equations as a material parameter constant. The graded material is distributed through the beam thickness by a generalized power law function. The beam is simply supported, and it is assumed to be thin. Therefore, the kinematic assumptions of Euler-Bernoulli beam theory are held. The mathematical model is solved numerically using the finite element method. Results demonstrate effects of porosity type, material gradation, and nanoscale parameters on the free vibration of nanobeam. The proposed model is effective in vibration analysis of NEMS structure manufactured by porous functionally graded materials.

• Journal of Electrical Engineering and Technology
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• 제13권1호
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• pp.521-531
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• 2018

This paper presents a procedure for field measurements which provides a generalized Narrowband Power Line Communications (NB-PLC) channel model for low voltage (LV) access network in order to deploy advanced metering infrastructure (AMI) within Lahore, Pakistan. The measurements of allocated sites were performed in the residential (urban and rural), industrial and commercial electricity consumers for the NB-PLC channel modeling of overhead transmission lines (TLs). On the basis of extensive field measurement results, the average attenuation profile and transfer functions are presented. The results obtained from field measurements are validated by comparing them with a proposed Simulink model. A close agreement in the measured and simulated transfer function (TF) results is observed. The proposed Simulink model is an effort to model the NB-PLC channels in an effective way, especially in South Asian countries.