• Journal of information and communication convergence engineering
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• 제2권1호
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• pp.26-31
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• 2004

In the last few years, The Semantic Web has increased the interest in ontologies. Ontology is an essential component of the semantic web. Ontologies continue to change and evolve. We consider the management of versions in ontology. We study a set of changes based on domain changes, changes in conceptualization, metadata changes, and temporal dimension. In many cases, we want to be able to search in historical versions, query changes in versions, retrieve versions on the temporal dimension. In order to support an ontology query language that supports temporal operations, we consider temporal dimension includes transaction time and valid time. Ontology versioning brings about massive amount of versions to be stored and maintained. We present the storage policies that are storing all the versions, all the sequence of changed element, all the change sets, the aggregation of change sets periodically, and the aggregation of change sets using a criterion. We conduct a set of experiments to compare the performance of each storage policies. We present the experimental results for evaluating the performance of different storage policies from scheme 1 to scheme 5.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2000년도 ITC-CSCC -1
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• pp.329-332
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• 2000

Research interests on temporal data have been almost focused on data models. There has been relatively less research in the area of temporal data management. In this paper, we propose two data migration strategies based on time-segmented storage structure: the migration strategy by Time Granularity, the migration strategy by LST-GET. We describe the criterion for data migration and moving process. We simulated the performance of the migration strategy by Time Granularity in order to compare it with non-segmentation method. We compared and analyzed two data migration strategies for temporal data.

• Spatial Information Research
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• 제20권3호
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• pp.95-106
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• 2012

최근 무선 액세스 망의 범위가 증가하고 발전함에 따라 다양한 분야에서 u-GIS 서비스가 지원되고 있으며, 특히 모바일 환경에서의 u-GIS 서비스를 위해 시공간 데이터가 널리 활용되고 있다. 그러나 모바일 환경에서 활용되는 시공간 데이터에 대한 표준이 없으므로 서로 다른 시공간 데이터를 사용하는 모바일 u-GIS 서비스 간의 상호운용성을 위한 효율적인 시공간 데이터 처리 기술이 필요하다. 또한 모바일 장치의 저용량과 낮은 성능을 고려한 시공간 데이터의 수집, 저장, 관리 시스템이 필수적이다. 따라서 본 논문에서는 모바일 환경에서 시공간 데이터의 효율적인 관리를 위해 GML 기반의 질의 처리 시스템을 설계 및 구현하였다. GML 기반 시공간 질의 처리 시스템은 GML 문서의 특성인 상호운용성을 유지하고 저장 효율성을 높이기 위해 GML 스키마와 저장 테이블을 매핑하는 구조형 저장 방식과 Fast Infoset 기법을 이용한 바이너리 XML 저장 방식을 제공한다. 그리고 저장된 GML 문서의 시공간 데이터에 대한 신속한 질의 처리를 위하여 시공간 연산자를 제공한다. 마지막으로 본 논문에서 개발한 시스템을 가상 시나리오에 적용하여 본 시스템이 u-GIS 서비스를 위한 시스템으로 활용될 수 있음을 확인하였다.

• 한국농공학회논문집
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• 제59권2호
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• pp.29-36
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• 2017

The objective of this study was to analyze the temporal and spatial characteristics of agricultural drought by tracking the daily reservoir storage in Chungnam province. All daily records of the percent of reservoir storage from 2000 to 2015 were collected for 130 irrigation reservoirs from the RIMS (Rural Infrastructure Management System). The temporal change of province-wide average reservoir storage and the statistics showed that the annual average and minimum percent of reservoir storage in 2015 were extremely low like as those in the historical drought years of 2001 and 2012. The minimum reservoir storage on record was a 41 % at the end of September and remained far less than its historical average even until the end of the year. Furthermore, the annual average reservoir storage (68.3 %) recorded the lowest on record since 2000. In addition, about half of 130 major irrigation reservoirs in Chungnam fell into the risk of water shortage below 30 % full, and, in terms of annual minimum reservoir storage, the 79 reservoirs yielded lower storage in 2015 comparing with the measured in another drought year, 2001. On the other hand, irrigation reservoirs of comparatively worse storage condition revealed to be mostly located on the inside, such as Cheongyang-gun and Hongsung-gun. Conclusively, the low reservoir storage, still far below average even on December 2015, induced a serious concern about that more extreme drought would happen in the next spring.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제6권7호
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• pp.1756-1776
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• 2012

Wireless sensor networks (WSNs) are likely to be more prevalent as their cost-effectiveness improves. The spectrum of applications for WSNs spans multiple domains. In environmental sciences, in particular, they are on the way to become an essential technology for monitoring the natural environment and the dynamic behavior of transient physical phenomena over space. Existing sensor network query processors (SNQPs) have also demonstrated that in-network processing is an effective and efficient means of interaction with WSNs for performing queries over live data. Inspired by these findings, this paper investigates the question as to whether spatio-temporal and historical analysis can be carried over WSNs using distributed query-processing techniques. The emphasis of this work is on the spatial, temporal and historical aspects of sensed data, which are not adequately addressed in existing SNQPs. This paper surveys the novel approaches of storing the data and execution of spatio-temporal and historical queries. We introduce the challenges and opportunities of research in the field of in-network storage and in-network spatio-temporal query processing as well as illustrate the current status of research in this field. We also present new areas where the spatio-temporal and historical query processing can be of significant importance.

• 한국정보처리학회논문지
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• 제6권4호
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• pp.851-867
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• 1999

Numerous proposals for extending the relational data model as well as conceptual and object-oriented data models have been suggested. However, there has been relatively less research in the area of defining segmented storage structure and data migration strategies for temporal data. This paper presents the segmented storage structure in order to increment search performance and the two data migration strategies for segmented storage structure. this paper presents the two data migration strategies : the migration strategy by Time granularity, the migration strategy by LST-GET. In the migration strategy by Time Granularity, the dividing time point to assign the entity versions to the past segment, the current segment, and future segment is defined and the searching and moving process for data validity at a granularity level are described. In the migration strategy by LST-GET, we describe the process how to compute the value of dividing criterion. searching and moving processes are described for migration on the future segment and the current segment and entity versions 새 assign on each segment are defined. We simulate the search performance of the segmented storage structure in order to compare it with conventional storage structure in relational database system. And extensive simulation studies are performed in order to compare the search performance of the migration strategies with the segmented storage structure.

• Korean Journal of Hydrosciences
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• 제5권
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• pp.33-43
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• 1994

This study is to determine the critical duration of design rainfall and to utilize it for the design of detention pond with pump station. To examine the effect of the duration and temporal distribytion of the design rainfall, Huff's quartile method is used for the 9 cases of durations (ranges from 20 to 240 minutes) with ten years return period, and the ILLUDAS model is used for runoff analysis. The storage ratio, which is the ratio of maximum storage amounts to total runoff volume, is introduced to determine the criticalduration of design rainfall. The duration which maximizes the storage ratio is adopted as the critical duration. This study is applied to 18 urban drainage watercheds with pump station in Seoul, of which the range of watershed area is 0.24~12.70$km^2$. The result of simulation shows that the duration which maximizes storage ratio is 30 and 60 minutes on the whole. It is also shown that the storage ratios of 2nd - and 3rd-quartile pattern are larger than those of 1st- and 4th-quartile pattern of temporal distribution. A simplified empirical formula for Seoul area is suggested by the regression analysis between the maximum storage ratio and the peak ratio. This formula can be utilized for the preliminary design and planning of detention pond with pump station.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1996년도 하계학술대회 논문집 B
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• pp.1395-1397
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• 1996

Many of the existing neural associative memories are trained and recalled in separate modes and are not suitable for temporal pattern storage and classification in that user must specify the time and length of input patterns. In this paper, a new on-line temporal associative memory model is presented. This memory is structured in layers of neurons and each neuron has limited number of weights so that calculation complexity can be considerably reduced and processing of patterns can be achieved in real time.

• Journal of information and communication convergence engineering
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• 제5권2호
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• pp.159-163
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• 2007

RFID applications are mostly associated with the timestamp when the events occur. For managing RFID data we need to design data modeling for RFID data to support monitoring and temporal queries. In this paper, we propose a temporal RFID data modeling to maintain the history of events and state changes and to monitor the states of RFID objects. This data modeling involves essential basic operations for RFID data to monitor the information of RFID objects and to support temporal queries. Filter operations can achieve better query performance and obtain efficient storage space usage. It is possible to adapt into different temporal business applications.

• 분석과학
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• 제24권3호
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• pp.212-218
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• 2011

본 연구에서는 5종류의 황화합물질($H_2S$, $CH_3SH$, DMS, $CS_2$, DMDS)을 10 ppb (nmol/mol) 수준으로 포함하는 기체상 표준시료를 Teldlar bag에 담은 후 시차를 두고 30일 동안의 기간에 걸쳐 농도변화를 분석하였다. 황성분의 시간적 안정도를 파악하기 위해, 백에 보존한 시료의 보존방식과 분석시점에 대한 결정을 두 가지 상이한 접근방식으로 비교하였다. 이를 통해 시료의 장기적 보관방식과 분석시스템의 일관성에 대한 특성을 동시에 평가하고자 하였다. 이를 위하여, 첫 번째로 전체 보관기간 동안 분석할 시료를 일괄적으로 준비하여 이들을 시간대별로 하나씩 분석하는 Forward(F)보전방식으로 진행하였다. 두 번째로는 시료를 시간의 경과에 따라 순차적으로 준비하고, 종료시점에 모두 일괄적으로 분석하는 Reverse(R)방식으로 접근하였다. 이를 유의수준 90% 기준으로 t-테스트를 적용하여, 두 가지 분석방식의 자료들간에 차이점을 짝비교 방식으로 검정하였다. 이때 $H_2S$, $CH_3SH$, DMDS성분의 결과는 유의한 차이가 존재하는 것으로 나타났다. 본 실험의 결과, 분자량이 가벼운 황성분들($H_2S$와 $CH_3SH$)과 무거운 황성분들(DMS, $CS_2$, DMDS)간의 경시적 안정도에는 현저한 차이가 존재하는 것을 확인였다. 그러나 두 방식 모두 농도가 감소하는 상대적 경향은 성분 별로 일치하였다.