• Journal of KIISE:Databases
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• v.33 no.2
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• pp.201-213
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• 2006

A time-series database is a set of time-series data sequences, each of which is a list of changing values of the object in a given period of time. Subsequence matching is an operation that searches for such data subsequences whose changing patterns are similar to a query sequence from a time-series database. This paper addresses a performance issue of time-series subsequence matching. First, we quantitatively examine the performance degradation caused by the window size effect, and then show that the performance of subsequence matching with a single index is not satisfactory in real applications. We argue that index interpolation is fairly useful to resolve this problem. The index interpolation performs subsequence matching by selecting the most appropriate one from multiple indexes built on windows of their inherent sizes. For index interpolation, we first decide the sites of windows for multiple indexes to be built. In this paper, we solve the problem of selecting optimal window sizes in the perspective of physical database design. For this, given a set of query sequences to be peformed in a target time-series database and a set of window sizes for building multiple indexes, we devise a formula that estimates the cost of all the subsequence matchings. Based on this formula, we propose an algorithm that determines the optimal window sizes for maximizing the performance of entire subsequence matchings. We formally Prove the optimality as well as the effectiveness of the algorithm. Finally, we perform a series of extensive experiments with a real-life stock data set and a large volume of a synthetic data set. The results reveal that the proposed approach improves the previous one by 1.5 to 7.8 times.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2006.06b
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• pp.199-206
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• 2006

Today the harbor oscillation problems are the most significant factor to design harbors serving the very large ships. Large vessels moored in the elastic hawsers at the coastal harbors are often displaced due to the resonance between the long period waves and mooring system. The cargo handling may be interrupted and the hawsers may be broken, especially when the amplification becomes remarkable. The most significant harbor which is confronted with harbor oscillation problem in Korea is the Pohang New Port. Many cases of problems are being notified by the pilot association and local office of MOMAF. However, it is difficult to prevent the arrival of long waves causing oscillation within this harbor. Moreover, Government already started new port plan at the mouth of YoungIl Bay without treating problems occurred in the Pohang New Port. This study deals with the variation of harbor oscillation due to the construction of 4.1km breakwater at the bay mouth and new port plan. Numerical method used are fairly standard form from the extended mild slope equation. The obtained numerical results were compared with the field measurement from the previous study and this will bring a certain level of discussion and consideration of variation in the future port development.

• Journal of the Korean Geosynthetics Society
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• v.16 no.2
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• pp.121-129
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• 2017

There have been a number of water and sewer pipe breakdown reports followed by ground subsidence. Also, the excavating works for construction due to overcrowding of city have been common. Particularly, in urban areas ground becomes unstable because of the lowered lifeline sinkage followed excavation and backfilling. In order to solve the problem, some reinforcement works for ground by rod tamping or grouting have been applied. However, it is hard to predict when the buried utilities in underground will be damaged. Also, there is a limit for the underground exploration and investigation methods. Therefore, in this study, the estimated about the water soluble polymer pouch including poor mixed admixture which is designed to eliminate the dangerous factors. The reinforcement strength of this method was confirmed by verifying three points: meltiness in a certain period, water solubility in the ground water level, and characteristics of the pouch, which can be stored in daily conditions. It is also proved that this method allows to keep the ground from getting weakened in the installation of water and sewer pipe along with back filling materials.

• Journal of Korean Society of Rural Planning
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• v.26 no.4
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• pp.27-39
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• 2020

With the COVID-19 pandemic, the global economy has stagnated and our daily lives have changed. The rural economy is also experiencing damage, such as an average of 65% or more decrease in the number of visitors to rural experience resort villages due to the spread of COVID-19. In order to minimize the damage arising from the prolonged coronavirus, a hospitality system in response to changes in rural tourism behavior and consumer demand is needed to revitalize rural areas and maintain continuous economic independence. Therefore, this study attempted to find ways to utilize landscape resources such as education, culture, history, and ecology in order to complement the existing experience programs in connection with local resources and local environment. Wibong Village, which is the subject of the study, attempted to revitalize the village using the resources through the "Creative village creation" project in 2015. Due to poor management of historical resources, difficulty in operating experience programs, and response to changes in the natural environment, the rate of implementation of the project plan was very low. Currently, the demand for experience is also decreasing due to the COVID-19 effect, so it was judged that it was necessary to develop an experience village program suitable for the needs of experienced visitors by discovering additional local resources for the continuous operation of the experience village. In order to solve the problem of the use of landscape resources and the spatial composition of the study site, additional investigations of local resources were made, and an experience program course that could be operated by theme was proposed by configuring a space suitable for the use of landscape resources. By dividing the additionally investigated landscape resources into history, ecology, and region, an experiential course was created to separate the traffic lines, and the space composition for large-scale experienced visitors that had been previously operated was constructed in a form suitable for the post-corona era. In addition, at least two experiential tour courses that can be operated by period were proposed to maintain economic effects. Starting with this study, if further research on the creation and spatial composition of a rural experience village centered on the connection with the region, it will be used as research results that can be referenced in projects such as village creation, rural space planning, and living area analysis. It is expected that it will be able to effectively cope with the construction of a rural area suitable for the post-corona era, where demand is expected to increase in the future.

• Korean Journal of Soil Science and Fertilizer
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• v.31 no.4
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• pp.315-323
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• 1998

Soil aggregate distribution and its relation to wind erosion were examined for the surface soil of the experimental plots for grasses in the New Incheon International Airport, of which soil was reclaimed with sea sands in the Youngjong Island. The soil aggregate with the size between 0.10 and 0.84mm was 74 percents. The 6 percents of the soil aggregates were non-erodible. With this aggregate distribution the wind erodiblity of the soil, I. was $380Mg\;ha^{-1}\;yr^{-1}$ with I value and climatic factor calculated for the dry period from November to May, $45.2Mg\;ha^{-1}\;yr^{-1}$ of the surface soil were estimated to be eroded. The erodible particles with 0.37mm diameter could fly to 17.8, 29.9 and 49.8 meters by saltation at wind speed of 7, 9 and $15m\;s^{-1}$, respectively. The wind erosion could be reduced by increasing vegetation coverage and applying hydrophyllic soil conditioner.

• Journal of Korean Society of Transportation
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• v.27 no.5
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• pp.85-95
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• 2009

Congestion on expressways is increasing in spite of continuous road construction. In enlargement of expressway capacity to lessen congestion, a long period is needed and in the case of traffic congestion, it would be impossible to avoid long periods of traffic congestion. So, it is necessary to cope with traffic congestion through continuous traffic condition monitoring, analysis of the causes of congestion and the development of alternatives before traffic conditions worsen. A congestion index that can express traffic operating conditions measurably is needed to monitor those conditions. Thus, in this research, a new congestion index, the Traffic Condition Index (TCI), is developed. TCI is able to evaluate roads that have different grades (or design speeds) and to judge traffic condition as good, fair and poor (congested). In addition, TCI has merits in that it can strengthen the function of existing Freeway Traffic Management Systems (FTMS) and can be applied to congestion management easily: TCI calculates congestion intensity and severity using data obtained from existing FTMS. In order to validate TCI, it was applied to the Kyungbu Expressway and the Seohaean Expressway. As a result, TCI shows a good performance in the aspect of applicability and ability of presentation of traffic conditions compared with travel speed and Travel Time Index (TTI).

• Journal of Wetlands Research
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• v.8 no.3
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• pp.29-38
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• 2006

Digital Elevation Model (DEM) of intertidal flat can be widely used not only for scientific fields, coastal management, fisheries, ocean safety, military, but also for understanding natural and artificial topographic changes of the tidal flat. In this study, we generated DEM of the Ganghwado southern intertidal flat, the largest tidal flat in the west coast of the Korean Peninsula, using waterline method and interferometric synthetic aperture radar (InSAR). Constructed DEM which applied waterline method to the Landsat-5 TM and Landsat-7 ETM+ images closely expresses overall topographic relief of tidal flat. We found that the accuracy was determined by the number of waterlines which reflect various tidal conditions. The application of InSAR to the ERS-1/2 and ENVISAT images showed that only ERS-1/2 tandem pairs successfully generated DEM in the part of northern Yeongjongdo, but construction of DEM in the other areas was difficult due to the low coherence caused by a lot of surface remnant waters. In the near future, Kompsat-2 will provide satellite images having multi-spectral and high spatial resolution within a relatively short period at different sea levels. Application of waterline method to these images will help us construct a high precision tidal flat DEM. Also, we should develop DEM generation method using single-pass microwave satellite images.

• The Journal of Art Theory & Practice
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• no.3
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• pp.51-66
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• 2005

With the advent of the time when the competitiveness of a nation or a city can be evaluated by the extent of cultural reception, the art exhibitions, like other genres of art, are actively held in various ways by different institutions. The spaces of exhibition offered not only by public museums and galleries but also by private galleries, alternative spaces and open-air exhibition spots are being increased. Likewise, the number of exhibitions organized on a large scale by Biennales and local governments is on the increase. In accordance with actual tendency, the Ministry of Culture and Tourism has planned to increase the number of museums and galleries up to 500 by the year of 2011. Under these circumstances, the actual situation shows that the central and local governments are adopting beneficial measures to support the private galleries such as permission of construction on green belt areas and tax deduction. That is, our society has come to realize that the necessity and importance of public as well as private galleries to play their roles as cultural and educational institution. Now, the number of galleries is growing. Exhibitions are held everywhere. Therefore, spectators have more chance to visit them than before. With these conditions and the growing number of amateurs, social interest in curator organizing exhibitions is getting popular. Because of the rise of curatorial popularity on the social level, the influence of curators which is exercised within the gallery seems to become gradually enlarged. In reality, it is true that the curatorial influence cannot be ignored more than ever for appear in various fields their new features made from their professional cometence. The function of gallery is more strengthened and its position is more heightened than those in 80s. For these reasons, the curators whose playground is the gallery, they may be regarded as invisible power to the artists. Futhermore, their influence as such seems to be more likely because our world of art does not still have any reliable system of art criticism. Nevertheless, considering the actual situation in which national and public galleries as cultural institution would rather exist on the local sentiments or political dynamics than on autonomy, there must be some restrictions for the galleries and the curators to obtain the power. In this context, the actual moment is looked upon as transitional period to make the curatorship settled down. Before discussing the power relevant to curatorship, we are going to examine first the role and function of curator and then the new curatorial role and function at the age of information. Finally, we will see in sequence the development and problems of curatorship, the power and dilemmas of curator.

• Journal of the Korean GEO-environmental Society
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• v.15 no.2
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• pp.17-25
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• 2014

In the present study, it were performed an unconfined compression test and a field applicability test according to a mixed ratio of SS, soil type and curing period to analyze strength and deformation characteristic in order to evaluate engineering characteristics of soil mixed pavements using the eco-friendly soil stabilizer (SS). The test results revealed that SS mixed soil shows fast strength development at the initial curing time while 28-day strength amounted for 97% of the final strength. Furthermore, coarse-grained dredged sand (DS) and weathered granitic soil (WGS) have a larger ratio of deformation coefficient with respect to unconfined compressive strength than fine-grained dredged clay (DC) and organic soil (OS). Moreover, a comparison test between natural and forced drying conditions was conducted and test result showed 54% to 67% of strength degradation while having 55% to 63% of strength degradation in the freezing and thawing test result. Finally, a repeated loading test result showed that DS experiences up to 35% of strength reduction compared to initial strength under 10,000 times loading in maximum. Thus, it was validated that an appropriate amount of fine-grained sand is necessary to secure resistance capability to repeated loading.

• Journal of agriculture & life science
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• v.44 no.6
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• pp.171-182
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• 2010

Water demand and resource at a watershed scale were investigated to prepare for long-term water planning of the Namgang sub-basin. The quantity of water resource was defined as average annual runoff by a simple Tank model with three serial tanks, and water demand for public, industrial, agricultural and the other uses was determined using the per-unit method employed in the Water Vision 2020, the Ministry of Construction and Transportation. The results showed that total amount of water resources in the Namgang sub-basin was estimated as about $935,414{\times}10^{3}m^3/yr$ for a 10-year period from 2000 to 2009 and the water withdrawals in public, industrial, agricultural and other sector were derived as $105,493{\times}10^{3}m^3/yr$, $32,686{\times}10^{3}m^3/yr$, $243,194{\times}10^{3}m^3/yr$, and $81,615{\times}10^{3}\;m^3m^3/yr$, respectively. In addition, the Namgaram Inno-city project could increase the overall water demand by $17,156{\times}10^{3}\;mm^3/yr$ due to the population influx.