• Title/Summary/Keyword: Spatio-temporal changes

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Study on Improvement of Calibration/Validation of SWAT for Spatio-Temporal Analysis of Land Uses and Rainfall Patterns (강수패턴과 토지이용의 시공간적 분석을 위한 SWAT모형의 검보정 개선방안 연구)

  • Lee, Ji-Won;Kum, Donghyuk;Kim, Bomchul;Kim, Young Sug;Jeong, Gyo-Cheol;Kim, Ki-Sung;Choi, Joong-Dae;Lim, Kyoung Jae
    • Journal of Korean Society on Water Environment
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    • v.29 no.3
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    • pp.365-376
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    • 2013
  • The purpose of this study was to evaluate effects of spatio-temporal changes in land uses and rainfall magnitude using the Soil and Water Assessment Tool (SWAT). Prior of application of the model to real-world problem, the model should be calibrated and validated properly. In most modeling approaches, the validation process is done assuming no significant changes occurring at the study watershed between calibration and validation periods, which is not proper assumption for agricultural watersheds. If simulated results obtained with calibrated parameters match observed data with higher accuracy for validation period, this does not always mean the simulated result represents rainfall-runoff, pollutant generation and transport mechanism for validation period because temporal and spatial variables and rainfall magnitude are often not the same. In this study SWAT was applied to Mandae study watershed in Korea to evaluate effects of spatio-temporal changes in landuses using 2009 and 2010 crop data for each field at the watershed. The Nash-Sutcliffe model efficiency (NSE) values for calibration and validation with either 2009 or 2010 was evaluated and the NSE value for calibration with 2009 and calibration with 2010 were compared. It was found that if there is substantial change in land use and rainfall, model calibration period should be determined to reflect those changes. Through these approaches, inherent limitation of the SWAT, which does not consider changes in land uses over the simulation period, was investigated. Also, Effects of changes in rainfall magnitude during calibration process were analyzed.

Spatio-Temporal Distributional Changes of Bamboo (대나무의 시.공간적 분포역 변화)

  • 공우석
    • Journal of the Korean Geographical Society
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    • v.36 no.4
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    • pp.444-457
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    • 2001
  • Present work aims to analyse the spatio-temporal distribution of Korean bamboos. The northern limit of Korean bamboo species occurs at Baekryung Island(124°10'E, 37°55'N), Hoochang(41°22'N) and Myungchon(129°41\`E, 41°10'N). The presence of bamboo fossils in Korea dates back from Tertiary, but widespread use of bamboos can be noticed since 1454. Reconstructed ranges and temporal changes of bamboo, based upon the eight historical records from 15th to 20th centuries, indicates that both climatic and anthropogenic factors were responsible for the changes of distributional range. The spread of bamboos was balanced by its disappearance due to regional development, and the total bamboo area showing little change. Due to the tendency to spread extensively by means of underground stems, bamboos often invade adjacent forests and disturb natural vegetation. Proper management and conservation strategies, therefore, are required for the maintenance of rural landscape.

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Analysis of Watershed Runoff and Sediment Characteristics due to Spatio-Temporal Change in Land Uses Using SWAT Model (SWAT 모형을 이용한 시.공간적 토지 이용변화에 따른 유량 및 유사량 특성분석)

  • Shin, Yong-Chul;Lim, Kyoung-Jae;Kim, Ki-Sung;Choi, Joong-Dae
    • KCID journal
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    • v.14 no.1
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    • pp.50-56
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    • 2007
  • In this study, the Soil and Water Assessment Tool (SWAT) model was used to assess spatiotemporal effects on watershed runoff and sediment characteristics due to land uses changes from 1999 to 2002 at the small watershed, located in Chuncheon-si, Gangwon province. The annual average flow rate of Scenario I (long-term simulation using land use of 1990), II (long-term simulation using land use of 1996), III(long-term simulation using land use of 200) and IV(simulation using land use of 1990, 1995, and 2000) in long-term simulation) using the SWAT model were 29,997,043 m3, 29,992,628 m3, 29,811,191 m3 and 29,931,238 m3, respectively. It was shown that there was no significant changes in estimated flow rate because no significant changes in land uses between 1990 and 2000 were observed. The annual average sediment loads of Scenarios I, II, III and IV for 15 year period were 36,643 kg/ha, 45,340 kg/ha , 27,195 kg/ha and 35,545 kg/ha, respectively. The estimated annual sediment loads from Scenarios I, II, and III, were different from that from the scenario IV, considering spatio-temporal changes in land use and meterological changes over the years, by 10%, 127%, and temporal changes in land use and meterological changes over the years, by 10%, 127%, and 77%. This can be explained in land use changes in high soil erosion potential areas, such as upland areas, within the study watershed. The comparison indicates that changes in land uses upland areas, within the study watershed. The comparison indicates that changes in land uses can affect on sediment yields by more than 10%, which could exceed the safety factor of 10% in Total Maximum Daily Loads (TMDLs). It is, therefore, recommended that not only the temporal analysis with the weather input data but also spatial one with different land uses need to be considered in long-term hydrology and sediment simulating using the SWAT model

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Research on Application of Spatial Statistics for Exploring Spatio-Temporal Changes in Patterns of Commercial Landuse (상업적 토지이용 패턴의 시공간 변화 탐색을 위한 공간통계 기법 적용 연구)

  • Shin, Jung-Yeop;Lee, Gyoung-Ju
    • Journal of the Korean Geographical Society
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    • v.42 no.4
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    • pp.632-647
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    • 2007
  • Lots of geographic phenomena have dynamic spatial patterns with time changes, and there have been lots of researches on exploring these dynamic spatial patterns. However, most of these researches focused on the static pattern analysis in a given period, rather than dealing with dynamic changes in the spatial pattern over time with the continual or cumulative perspective. For this reason, investigation of the inertia of spatial process in terms of temporal changes is needed. From this background, the purpose of this paper is to propose the methodology to explore the changes in spatial pattern cumulatively by considering the inertia of the spatial statistics over time, and to apply it to the case study That is, we introduce the new spatial statistic, and produce the z-values of the statistic using Monte Carlo Simulation, and then to explore the changes in spatial patterns over time cumulatively. To do this, the method to combine the J statistic with CUSUM statistic for exploring spatial patterns, and to apply it to the changes in the commercial landuse in Erie County, New York State. Through the proposed method for spatio-temporal Patterns, we could explore continual changes effectively in the spatial patterns reflecting the statistics by temporal spot cumulatively.

Exploring Spatio-Temporal Variations of Land Price in Daegu Metropolitan City (대구시 지가의 시공간적 변화 탐색)

  • Kim, Kamyoung
    • Journal of the Korean association of regional geographers
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    • v.18 no.4
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    • pp.414-432
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    • 2012
  • Land price is a kind of text to read urban spatial structure. The purpose of this paper is to inquire into the characteristics of Daegu's urban structure and its change in time through exploring spatio-temporal variations of land price with a detailed spatial and temporal resolution. To achieve this, land value surfaces were represented using the officially assessed land price every other year from 1995 to 2011. Through mapping and exploring spatio-temporal patterns and fluctuation rates of land price for this period, changes in urban structure, the effects of local decision makings such as Greenbelt adjustment, housing site development, and gentrification, and the effects of business fluctuations or policies at global or national scales could be caught. In addition, the trends for suburbanization and multi-centric urban form could be examined from the results of a negative exponential model explaining the effect of distance from an urban center on spatial variation of land price. These results demonstrate that urban analysis using land price mirroring spatial decision making at various scales could deepen understanding for internal structure and change of a city and provide useful information for establishing regional and urban development policies and evaluating their effects.

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Multiple Person Tracking based on Spatial-temporal Information by Global Graph Clustering

  • Su, Yu-ting;Zhu, Xiao-rong;Nie, Wei-Zhi
    • KSII Transactions on Internet and Information Systems (TIIS)
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    • v.9 no.6
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    • pp.2217-2229
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    • 2015
  • Since the variations of illumination, the irregular changes of human shapes, and the partial occlusions, multiple person tracking is a challenging work in computer vision. In this paper, we propose a graph clustering method based on spatio-temporal information of moving objects for multiple person tracking. First, the part-based model is utilized to localize individual foreground regions in each frame. Then, we heuristically leverage the spatio-temporal constraints to generate a set of reliable tracklets. Finally, the graph shift method is applied to handle tracklet association problem and consequently generate the completed trajectory for individual object. The extensive comparison experiments demonstrate the superiority of the proposed method.

Spatio-Temporal Index Structure for Trajectory Queries of Moving Objects in Video (비디오에서 이동 객체의 궤적 검색을 위한 시공간 색인구조)

  • Lee, Nak-Gyu;Bok, Kyoung-Soo;Yoo, Jae-Soo;Cho, Ki-Hyung
    • The KIPS Transactions:PartD
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    • v.11D no.1
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    • pp.69-82
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    • 2004
  • A moving object has a special feature that it's spatial location, shape and size are changed as time goes. These changes of the object accompany the continuous movement that is called the trajectory. In this paper, we propose an index structure that users can retrieve the trajectory of a moving object with the access of a page. We also propose the multi-complex query that is a new query type for trajectory retrieval. In order to prove the excellence of our method, we compare and analyze the performance for query time and storage space through experiments in various environments. It is shown that our method outperforms the existing index structures when processing spatio-temporal trajectory queries on moving objects.

Perspectives on the Applicatio of Remote Sensing for Observation of Ocean Environments (해양환경관측을 위한 원격탐사의 활용과 그 전망)

  • 유신재;정종철
    • Korean Journal of Remote Sensing
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    • v.15 no.3
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    • pp.277-288
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    • 1999
  • The aim of this review is to provide perspectives on the application of remote sensing techniques for observation of marine environmental changes on various spatio-temporal scales. Currently available remote sensing technologies are reviewed and future direction is suggested. For better utilization of remote sensing, a comprehensive plan should be developed by a demand-side and problem-solving approach. Marine environmental changes should be observed on proper spatio-temporal scales where the processes occur. For appropriate observation and monitoring of various environmental changes in coastal regions, more sensors must be utilized. Platforms other than satellites should also be utilized to expand the spatio-temporal scales of observation. Calibration/validation activities, required for accurate interpretation of remotely sensed data, could utilize buoys and ship-of-opportunity sensors. It is desirable that such systems by developed as a part of an integrated monitoring network.

Reliability and Validity of a Smartphone-based Assessment of Gait Parameters in Patients with Chronic Stroke (만성 뇌졸중 환자에서 스마트폰을 이용한 보행변수 평가의 신뢰도와 타당도)

  • Park, Jin;Kim, Tae-Ho
    • Journal of the Korean Society of Physical Medicine
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    • v.13 no.3
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    • pp.19-25
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    • 2018
  • PURPOSE: Most gait assessment tools are expensive and require controlled laboratory environments. Tri-axial accelerometers have been used in gait analysis as an alternative to laboratory assessments. Many smartphones have added an accelerometer, making it possible to assess spatio-temporal gait parameters. This study was conducted to confirm the reliability and validity of a smartphone-based accelerometer at quantifying spatio-temporal gait parameters of stroke patients when attached to the body. METHODS: We measured gait parameters using a smartphone accelerometer and gait parameters through the GAITRite analysis system and the reliability and validity of the smartphone-based accelerometer for quantifying spatio-temporal gait parameters for stroke patients were then evaluated. Thirty stroke patients were asked to walk at self-selected comfortable speeds over a 10 m walkway, during which time gait velocity, cadence and step length were computed from smartphone-based accelerometers and validated with a GAITRite analysis system. RESULTS: Smartphone data was found to have excellent reliability ($ICC2,1{\geq}.98$) for measuring the tested parameters, with a high correlation being observed between smartphone-based gait parameters and GAITRite analysis system-based gait parameters (r = .99, .97, .41 for gait velocity, cadence, step length, respectively). CONCLUSION: The results suggest that specific opportunities exist for smartphone-based gait assessment as an alternative to conventional gait assessment. Moreover, smartphone-based gait assessment can provide objective information about changes in the spatio-temporal gait parameters of stroke subjects.

Using multiple sequence alignment to extract daily activity routines of the elderly living alone

  • Lee, Bogyeong;Lee, Hyun-Soo;Park, Moonseo;Ahn, Changbum Ryan;Choi, Nakjung;Kim, Toseung
    • Advances in Computational Design
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    • v.4 no.2
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    • pp.73-90
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    • 2019
  • The growth in the number of single-member households is a critical issue worldwide, especially among the elderly. For those living alone, who may be unaware of their health status or routines that could improve their health, a continuous healthcare monitoring system could provide valuable feedback. Assessing the performance adequacy of activities of daily living (ADL) can serve as a measure of an individual's health status; previous research has focused on determining a person's daily activities and extracting the most frequently performed behavioral patterns using camera recordings or wearable sensing techniques. However, existing methods used to extract common patterns of an occupant's activities in the home fail to address the spatio-temporal dimensions of human activities simultaneously. Though multiple sequence alignment (MSA) offers some advantages - such as inherent containment of the spatio-temporal data in sequence format, and rapid identification of hidden patterns - MSA has rarely been used to extract in-home ADL routines. This research proposes a method to extract a household occupant's ADL routines from a cumulative spatio-temporal data log of occupancy collected using a non-intrusive method (i.e., a tomographic motion detection system). The findings from an occupant's 28-day spatio-temporal activity log demonstrate the capacity of the proposed approach to identify routine patterns of an occupant's daily activities and to reveal the order, duration, and frequency of routine activities. Routine ADL patterns identified from the proposed approach are expected to provide a basis for detecting/evaluating abrupt or gradual changes of an occupant's ADL patterns that result from a physical or mental disorder, and can offer valuable information for home automation applications by enabling the prediction of ADL patterns.