• 한국농림기상학회:학술대회논문집
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• 한국농림기상학회 2003년도 춘계 학술발표논문집
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• pp.39-41
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• 2003

The crop growth simulation model could be adopted to evaluate the impact not only of the long term climate change such as atmosphere $CO_2$ concentration rising and global warming but also of the predicted short term weather variability on the national crop production. There are several growth simulation models for predicting rice crop performance such as ORYZA1, CERES-Rice, Rice Clock Model, and SIMRIW.(omitted)

• 한국원자력학회:학술대회논문집
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• 한국원자력학회 1996년도 춘계학술발표회논문집(1)
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• pp.349-354
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• 1996

SACOM(Simulation Analyser with Cognitive Operator Model) is being developed at Korea Atomic Energy Research Institute to simulate human operator's cognitive characteristics during the emergency situations of nuclear power plans. An operator model with error mechanisms has been developed and combined into SACOM to simulate human operator's cognitive information process based on the Rasmussen's decision ladder model. The operational logic for five different cognitive activities (Agents), operator's attentional control (Controller), short-term memory (Blackboard), and long-term memory (Knowledge Base) have been developed and implemented on blackboard architecture. A trial simulation with a scenario for emergency operation has been performed to verify the operational logic. It was found that the operator model with error mechanisms is suitable for the simulation of operator's cognitive behavior in emergency situation.

• Spatial Information Research
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• 제21권5호
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• pp.1-6
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• 2013

하천의 흐름 특성과 더불어 하상 변동을 연계하여 분석하는 일은 하천관리에 있어 가장 기본적이면서도 중요하다. 상류에 건설되는 신규댐 등 다양한 목적의 수공구조물이 계획될 때 하류 하천의 하상변화에 미치는 영향은 향후 하천을 지속적이고 안정적으로 보존, 관리하는데 반드시 고려해야 할 사항이다. 본 연구에서는 내성천을 적용 대상으로 항공사진 등을 활용한 하천의 장기적인 지형변화 양상을 고찰하였다. 아울러 1차원 수치모형인 GSTARS를 적용하여 주요지점의 하상변동 영향을 분석하였다. 장기적인 지형변화 양상을 바탕으로 댐이 건설된 후 내성천의 관리방안을 모색해 볼 수 있을 것이다.

• 한국화재소방학회논문지
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• 제29권6호
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• pp.119-128
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• 2015

이 논문에서는 신축 후 약 2년이 경과한 전원주택에서 벽난로 가동 중에 벽난로로 인한 화재가 발생하여 전소된 사례에 대해 법원을 통해 소방서, 경찰서, 화재보험관련 조사기관, 주택을 시공한 건설회사와 벽난로를 시공한 벽난로제조업체로부터 제공받은 자료들을 분석하여 벽난로 옆 벽체의 목재기둥에 남아 있는 저온장기발화의 화재패턴을 근거로 벽난로 옆 벽체의 목재기둥에 벽난로 화실(火室)의 열이 전도되어 화재가 발생하였음을 입증하였다. 그리고 벽난로 옆의 목재기둥이 저온장기발화를 한 이유는 굴뚝에 환기를 위한 공기창을 설치하지 않았기 때문임을 화재시뮬레이션을 통해 입증하였다.

• 상하수도학회지
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• 제28권6호
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• pp.635-645
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• 2014

The changes of rainfall pattern and impervious covers have increased disaster risks in urbanized areas. Impervious covers such as roads and building roofs have been dramatically increased. So, it is falling the ability safety of flood defense equipments to exist. Runoff coefficient means ratio of runoff by whole rainfall which is able to directly contribute at surface runoff during rainfall event. The application of accurate runoff coefficients is very important in sewer pipelines design. This study has been performed to estimate runoff characteristics change which are applicable to the process of sewer pipelines design or various public facilities design. It has used the SHER model, a long-term runoff model, to analyze the impact of a rising impervious covers on runoff coefficient change. It thus analyzed the long-term runoff to analyze rainfall basins extraction. Consequently, it was found that impervious surfaces could be a important factor for urban flood control. We could suggest the application of accurate runoff coefficients in accordance to the land Impervious covers. The average increase rates of runoff coefficients increased 0.011 for 1% increase of impervious covers. By having the application of the results, we could improve plans for facilities design.

• 경영과학
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• 제30권1호
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• pp.139-148
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• 2013

A nuclear energy has been one of the most important sources to securely supply electricity in South Korea. Its weight in the national electricity supply has kept increasing since the first nuclear reactor was built in 1978. The country relies on the nuclear approximately 31.4% in 2012 and it is expected to increase to 48.5% in 2024 based on the long-term electricity supply plan announced by the Korean government. However, Fukushima disaster due to 9.0 magnitude earthquake followed by the tsunami has raised deep concerns on the security of the nuclear power plants. The policy makers of the country are much interested in analyzing the cost structure of the power supply in the case that the nuclear is diminished from the current supply portion. This research uses a stochastic model that aims to evaluate the long-term power supply plan and provides an extensive cost analysis on the changes of the nuclear power supply. To evaluate a power supply plan, the research develops a few plausible energy mix scenarios by changing the installed capacities of energy sources from the long-term electricity supply plan. The analyses show that the nuclear is still the most attractive energy source since its fuel cost is very much stable compared to the other sources. Also the results demonstrate that a large amount of financial expenditure is additionally required every year if Koreans agree on the reduction of nuclear to increase national security against a nuclear disaster.

• Smart Structures and Systems
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• 제31권1호
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• pp.45-56
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• 2023

Vibration-based structural health monitoring is used to ensure the safety of structures by installing sensors in structures. The peak picking method, one of the applications of vibration-based structural health monitoring, is a method that analyze the dynamic characteristics of a structure using the peaks of the frequency response function. However, the results may vary depending on the person predicting the peak point; further, the method does not predict the exact peak point in the presence of noise. To overcome the limitations of the existing peak picking methods, this study proposes a new method to automate the modal analysis process by utilizing long short-term memory, a type of recurrent neural network. The method proposed in this study uses the time series data of the frequency response function directly as the input of the LSTM network. In addition, the proposed method improved the accuracy by using the phase as well as amplitude information of the frequency response function. Simulation experiments and lab-scale model experiments are performed to verify the performance of the LSTM network developed in this study. The result reported a modal assurance criterion of 0.8107, and it is expected that the dynamic characteristics of a civil structure can be predicted with high accuracy using data without experts.

• Wind and Structures
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• 제38권2호
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• pp.147-160
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• 2024

The aerodynamic force is a significant component that influences the stability and safety of structures. It has unstable properties and depends on computer precision, making its long-term prediction challenging. Accurately estimating the aerodynamic traits of structures is critical for structural design and vibration control. This paper establishes an unsteady aerodynamic time series prediction model using Long Short-Term Memory (LSTM) network. The unsteady aerodynamic force under varied Reynolds number and angles of attack is predicted by the LSTM model. The input of the model is the aerodynamic coefficients of the 1 to n sample points and output is the aerodynamic coefficients of the n+1 sample point. The model is predicted by interpolation and extrapolation utilizing Unsteady Reynolds-average Navier-Stokes (URANS) simulation data of flow around a circular cylinder, square cylinder and airfoil. The results illustrate that the trajectories of the LSTM prediction results and URANS outcomes are largely consistent with time. The mean relative error between the forecast results and the original results is less than 6%. Therefore, our technique has a prospective application in unsteady aerodynamic force prediction of structures and can give technical assistance for engineering applications.

• 대한전자공학회논문지TC
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• 제42권9호
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• pp.41-48
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• 2005

본 논문에서 장시간 귀환 기법과 단시간 귀환 기법을 결합하는 MIMO 다중 사용자 시스템을 제안하고 성능을 분석하였다 통화 초기에 목표 심볼 오류와 목표 전송를을 고려하여 활성 안테나 수, 성상도, 전송 전력과 같은 장시간 귀환 기법을 수신단에서 전송단에 귀환한다. 이 후에 수신단에서 단시간귀환기법으로서 활성안테나 인덱스를 주기적으로 전송단에 알려준다. 모의실험을 통해 장시간 귀환 기법 또는 단시간 귀환 기법만을 적용하였을 경우보다 장시간 귀환 기법 방법에 단시간 귀환 기법을 적용하였을 경우에 우수한 성능 개선이 있음을 확인할 수 있었다.

• International journal of advanced smart convergence
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• 제12권4호
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• pp.55-62
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• 2023

Slotted-Aloha (S-Aloha) has been widely employed in random access networks owing to its simple implementation in a distributed manner. To enhance the throughput performance of the S-Aloha, connection-based slotted-Aloha (CS-Aloha) has been proposed in recent years. The fundamental principle of the CS-Aloha is to establish a connection with a short-sized request packet before transmitting data packets. Subsequently, the connected node transmits long-sized data packets in a batch of size M. This approach efficiently reduces collisions, resulting in improved throughput compared to the S-Aloha, particularly for a large M. In this paper, we address the short-term fairness of the CS-Aloha, as quantified by Jain's fairness index. Specifically, we evaluate how equitably the CS-Aloha allocatestime slots to all nodes in the network within a finite time interval. Through simulation studies, we identify the impact of system parameters on the short-term fairness of the CS-Aloha and propose an optimal transmission probability to support short-term fairness.