• IEIE Transactions on Smart Processing and Computing
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• 제5권6호
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• pp.430-439
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• 2016

Estimation and analysis of traffic jams plays a vital role in an intelligent transportation system and advances safety in the transportation system as well as mobility and optimization of environmental impact. For these reasons, many researchers currently mainly focus on the brilliant machine learning-based prediction approaches for traffic prediction systems. This paper primarily addresses the analysis and comparison of prediction accuracy between two machine learning algorithms: Naïve Bayes and K-Nearest Neighbor (K-NN). Based on the fact that optimized estimation accuracy of these methods mainly depends on a large amount of recounted data and that they require much time to compute the same function heuristically for each action, we propose an approach that applies multi-threading to these heuristic methods. It is obvious that the greater the amount of historical data, the more processing time is necessary. For a real-time system, operational response time is vital, and the proposed system also focuses on the time complexity cost as well as computational complexity. It is experimentally confirmed that K-NN does much better than Naïve Bayes, not only in prediction accuracy but also in processing time. Multi-threading-based K-NN could compute four times faster than classical K-NN, whereas multi-threading-based Naïve Bayes could process only twice as fast as classical Bayes.

• Earthquakes and Structures
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• 제16권3호
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• pp.311-320
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• 2019

Obelisks are historical monuments. There are several obelisks dating from ancient Egyptian period, located around various parts of the world. The city of Istanbul is a home to the Obelisk of Theodosius at the Hippodrome. Due to the expectation of a large event in the near future, the evaluation of seismic response of the Obelisk gets importance. Therefore, in this study structural dynamic behavior of the Obelisk was investigated using discrete element approach. Nonlinear dynamic analyses were performed using real and synthetic time series. Real and synthetic ground motions analyzed from this study seems consistent with the earthquake hazard levels that would be expected at the site of the Obelisk in the occurrence of an event of moment magnitude above 7.0 near Istanbul. Results are evaluated in terms of variation of displacement, relative displacement of adjacent blocks, normal stress and shear stress in time.

• Earthquakes and Structures
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• 제17권2호
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• pp.191-204
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• 2019

Near-field earthquake records including long-period high-amplitude velocity pulses can cause large isolation system displacements leading to buckling or rupture of isolators. In such cases, providing supplemental damping in the isolation system has been proposed as a solution. However, it is known that linear viscous dampers can reduce base displacements in case of near-field earthquakes but at the potential expense of increased superstructure response in case of far-field earthquakes. But can non-linear dampers with different levels of non-linearity offer a superior seismic performance? In order to answer this question, the effectiveness of non-linear viscous dampers in reducing isolator displacements and its effects on the superstructure response are investigated. A comparison with linear viscous dampers via time history analysis is done using a base-isolated benchmark building model under historical near-field and far-field earthquake records for a wide range of different levels of non-linearity and supplemental damping. The results show that the non-linearity level and the amount of supplemental damping play important roles in reducing base displacements effectively. Although use of non-linear supplemental dampers may cause superstructure response amplification in case of far-field earthquakes, this negative effect may be avoided or even reduced by using appropriate combinations of non-linearity level and supplemental damping.

• 상하수도학회지
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• 제10권2호
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• pp.88-103
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• 1996

The objective of this study is to develop stochastic and deterministic models which could be used to synthesize water application time series. Adaptive models using mulitivariate ARIMA(Transfer Function Model) are developed for daily urban water use forecasting. The model considers several variables on which water demands is dependent. The dynamic response of water demands to several factors(e.g. weekday, average temperature, minimum temperature, maximum temperature, humidity, cloudiness, rainfall) are characterized in the model by transfer functions. Daily water use data of Kumi city in 1992 are employed for model parameter estimation. Meteorological data of Seonsan station are utilized to input variables because Kumi has no records about the meteorological factor data.To determine the main factors influencing water use, autocorrelogram and cross correlogram analysis are performed. Through the identification, parameter estimation, and diagnostic checking of tentative model, final transfer function models by each month are established. The simulation output by transfer function models are compared to a historical data and shows the good agreement.

• Earthquakes and Structures
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• 제8권2호
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• pp.423-442
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• 2015

The effects of accidental eccentricity on the seismic response of four-storey steel buildings laterally stabilized by buckling restrained braced frames are studied. The structures have a square, symmetrical footprint, without inherent eccentricity between the center of lateral resistance (CR) and the center of mass (CM). The position of the bracing bents in the buildings was varied to obtain three different levels of torsional sensitivity: low, intermediate and high. The structures were designed in accordance with the seismic design provisions of the 2010 National Building Code of Canada (NBCC). Three different analysis methods were used to account for accidental eccentricity in design: (1) Equivalent Static Procedure with static in-plane torsional moments assuming a mass eccentricity of 10% of the building dimension (ESP); (2) Response Spectrum Analysis with static torsional moments based on 10% of the building dimension (RSA-10); and (3) Response Spectrum Analysis with the CM being displaced by 5% of the building dimension (RSA-5). Time history analyses were performed under a set of eleven two-component historical records. The analyses showed that the ESP and RSA-10 methods can give appropriate results for all three levels of torsional sensitivity. When using the RSA-5 method, adequate performance was also achieved for the low and intermediate torsional sensitivity cases, but the method led to excessive displacements (5-10% storey drifts), near collapse state, for the highly torsionally sensitive structures. These results support the current provisions of NBCC 2010.

• 한국콘텐츠학회논문지
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• 제9권4호
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• pp.364-371
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• 2009

나관중의 소설 삼국지에 등장하는 인물들에 대한 인간관계 네트워크를 구축하고 분석한 결과, 실제 사회 인간관계 및 사회 네트워크의 특성과 마찬가지로 척도 없는 네트워크 및 계층적 네트워크의 특성을 보여주었다. 지금까지 대부분 네트워크에 관한 연구는 정적인 측면을 중심으로 이루어졌다. 왜냐하면, 네트워크는 고정되어 있는 것이 아니라 시간 및 공간에 따라 다양하게 변화함에도 불구하고 동적인 면을 분석하기 위한 데이터가 충분하지 않기 때문이다. 소설 삼국지는 비교적 짧은 역사 속에서 다양한 등장인물(1,119 노드)과 인물들의 이합집산에 의한 다양한 인간관계(3,604 링크) 연결망을 형성하고 있기 때문에 시간에 따른 동적 네트워크의 분석을 위한 좋은 모델이 될 것이다. 본 연구는 시대적으로 형성되는 네트워크 특성을 분석하고, 주요 등장인물들의 상관관계와 등장인물의 가중치를 분석하여 연결망의 동역학적 특성을 살펴보았다. 따라서 본 연구는 실제 인간관계 및 사회 네트워크나 생명체를 구성하고 있는 분자들의 네트워크에 관한 동역학적 특성을 분석할 수 있는 가능성을 제시하고 있다.

• Journal of Information Technology Applications and Management
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• 제14권3호
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• pp.95-113
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• 2007

To minimize IT operational risks and the opportunity cost for lost business hours. it is necessary to have preparedness in advance and mitigation activities for minimization of a loss due to the business discontinuity. There are few cases that banks have a policy on systematic management, system recovery and protection activities against system failure. and most developers and system administrators response based on their experience and the instinct. This article focuses on the mitigation model development for minimizing the incidents of disk unit in IT operational risks. The model will be represented by a network model which is composed of the three items as following: (1) the risk factors(causes, attributes and indicators) of IT operational risk. (2) a periodic time interval through an analysis of historical data. (3) an index or an operational regulations related to the examination of causes of an operational risk. This article will be helpful when enterprise needs to hierarchically analyze risk factors from various fields of IT(information security, information telecommunication, web application servers and so on) and develop a mitigation model. and it will also contribute to the reduction of operational risks on information systems.

• Earthquakes and Structures
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• 제12권1호
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• pp.1-12
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• 2017

Historical earthquakes have shown that successive seismic events may occur in regions of high seismicity. Such a sequence of earthquakes has the potential to increase the damage level of the structures, since any rehabilitation between the successive ground motions is practically impossible due to lack of time. Few studies about this issue can be found in literature, most of which focused their attention on the seismic response of SDOF systems or planar frame structures. The aim of the present study is to examine the impact of seismic sequences on the damage level of 3D multistorey R/C buildings with various structural systems. For the purposes of the above investigation a comprehensive assessment is conducted using three double-symmetric and three asymmetric in plan medium-rise R/C buildings, which are designed on the basis of the current seismic codes. The buildings are analyzed by nonlinear time response analysis using 80 bidirectional seismic sequences. In order to account for the variable orientation of the seismic motion, the two horizontal accelerograms of each earthquake record are applied along horizontal orthogonal axes forming 12 different angles with the structural axes. The assessment of the results revealed that successive ground motions can lead to significant increase of the structural damage compared to the damage caused by the corresponding single seismic events. Furthermore, the incident angle can radically alter the successive earthquake phenomenon depending on the special characteristics of the structure, the number of the sequential earthquakes, as well as the distance of the record from the fault.

• 한국ITS학회 논문지
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• 제20권1호
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• pp.86-99
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• 2021

교통혼잡을 완화하기 위한 방안 중 하나로 도로 이용자에게 교통상황 예측정보를 제공함으로써 교통량을 분산 시켜 도로 이용 효율을 증대시키는 방법이 있다. 이를 위해서는 신뢰성이 보장되고 정량적인 실시간 교통 속도 예측이 필수적이다. 본 연구에서는 상황별 교통속도 분석을 기반으로 이력 속도 데이터와 이력 속도 외의 교통류에 상관관계가 있는 데이터를 LSTM 입력 데이터로 활용하였다. 정상 교통류 상황에 대응하여 속도를 예측하는 LSTM 모델과 유고상황에 대응하여 속도를 예측하는 CNN-LSTM 모델을 개발하여 유고발생 후 1시간까지 5분 단위로 교통속도 예측을 시도하였다. 모델의 검증은 테스트 데이터를 통하여 교통상황별 예측성능을 분석하였다. 그 결과 정상 교통류에서는 평균 7.43km/h, 유고상황에서는 7.66km/h의 오차율로 각각 예측되었다.

• 한국수자원학회논문집
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• 제55권9호
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• pp.657-668
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• 2022

하천 유량이 증가된 상태에서 집중호우의 발생은 유량과 강우량 모두 하천변 홍수피해에 영향을 미치게 된다. 또한, 하천변 사회·경제적 영향 수준에 따라 피해정도에 차이를 보이게 되며, 특히, 인구 및 자산 밀집도가 높은 경우 홍수대응에 필요한 충분한 예보 선행시간의 확보가 요구된다. 본 연구에서는 홍수대응에 필요한 시간적 여유의 확보를 통한 피해저감 효과를 증대하기 위해 앙상블 강우유출모델링을 활용한 홍수위험매트릭스를 구축하고, 그 적용성을 판단하고자 한다. 홍수위험매트릭스는 홍수피해 자료를 활용한 홍수피해 영향수준(X축)을 구성하고, 기상청 LENS 강우자료를 이용한 앙상블 강우유출모델링의 결과로 위험 홍수량의 발생 가능성을 예측(Y축)하여 확률예보에 기반한 예측이 가능하다. 이를 위해 과거 홍수피해 자료 및 정량적 홍수피해 평가방법을 이용한 홍수피해 영향수준 결정 방법을 제시하였다. 낙동강권역의 태화강유역 및 형산강유역의 홍수특보지점에 대하여 기존 홍수특보 자료 그리고 피해 발생 상황과 비교하였다. 그 결과 최대 3일전부터 홍수위험 발생시간 및 정도에 대한 예측이 가능한 것으로 분석되었다. 따라서 홍수대응에 필요한 예보 선행시간 확보를 통한 피해저감 활동에 도움이 되리라 판단된다.