• Journal of Korean Society of Rural Planning
• /
• v.8 no.1 s.15
• /
• pp.105-113
• /
• 2002

This investigation aims to provide basic data for rural village planning and rehabilitation planning. Public infrastructures of forty selected villages have been surveyed. Provision of facilities, user satisfaction, perceived problems, and conditions of maintenance have been surveyed for three classified types of infrastructures; 1) public utility spaces such as community hall, and parking lots, 2) public production infrastructures such as warehouses, and irrigation facilities, and 3) public infrastructures for living environments such as roads, water supply, and sewage system. All twenty smaller villages (ki-cho-ma-ul) had problems of poor conditions and insufficient spaces with community halls. Most of the smaller villages suffered from lack of public production infrastructures, or had problems of insufficient spaces and poor maintenance conditions. They also lacked good access roads with adequate right of ways. Only three villages were provided with sewage systems. In the twenty larger villages (myun-bo-ma-ul), though public utility spaces were provided for most of them (as an example, sixteen villages had welfare centers), they were not large enough and they were maintained in poor condition too. On the one hand twelve of the larger villages had farm machine service centers, only a few villages were equipped with warehouses. Many more public infrastructures for living environments were found in larger villages. However, only a few villages had pollution control facilities. Multidimensional scaling revealed groups of distinctive characteristics, in terms of public infrastructures, among smaller villages. It did not show any noticeable distinctions among larger villages.

• Journal of Korea Port Economic Association
• /
• v.26 no.2
• /
• pp.19-35
• /
• 2010

The purpose of this paper is to develop a benchmark of performance standards for Global Logistics Provider in the merging logistics market. The Data Envelopment Analysis (DEA) can be employed to compare and analyse the efficiencies of Global Logistics Provider(3PL, 4PL). That is because Global Logistics Providers are able to reach the highest level of efficiency by using Logistics institutions and Logistics service systematically. This research is focused on analyzing the efficiencies of top 40 Global Logistics Providers. The framework assumes that the Providers use three inputs to produce one output. The inputs include number of employees information system, and number of warehouses. The output is the annual turnover. The results show that Panalpina, C.H. Robinson Worldwide, Maersk Logistics/Damco, Hub Group, Lander Global Logistics on Global Logistics Providers are the efficient providers. This paper also allows the inefficient DMUs to establish their benchmarking strategies. The strategies are dependent on the assets such as number of employees, information system, and number of warehouses.

• Journal of KIISE:Databases
• /
• v.31 no.6
• /
• pp.585-595
• /
• 2004

A query processing is a critical issue in data warehouse environment since queries on data warehouses often involve hundreds of complex operations over large volumes of data. Data warehouses therefore build a large number of materialized views to increase the system performance. Which views to materialized is an important factor on the view maintenance cost as well as the query performance. The goal of materialized view selection problem is to select an optimal set of views that minimizes total query response time in addition to the view maintenance cost. In this paper, we present an efficient solution for the materialized view selection problem. Although the optimal selection of materialized views is NP-hard problem, we developed a feasible solution by utilizing the characteristics of relational operators such as join, selection, and grouping.

• Journal of Computing Science and Engineering
• /
• v.1 no.2
• /
• pp.177-194
• /
• 2007

Index selection is one of the most important decisions to take in the physical design of relational data warehouses. Indices reduce significantly the cost of processing complex OLAP queries, but require storage cost and induce maintenance overhead. Two main types of indices are available: mono-attribute indices (e.g., B-tree, bitmap, hash, etc.) and multi-attribute indices (join indices, bitmap join indices). To optimize star join queries characterized by joins between a large fact table and multiple dimension tables and selections on dimension tables, bitmap join indices are well adapted. They require less storage cost due to their binary representation. However, selecting these indices is a difficult task due to the exponential number of candidate attributes to be indexed. Most of approaches for index selection follow two main steps: (1) pruning the search space (i.e., reducing the number of candidate attributes) and (2) selecting indices using the pruned search space. In this paper, we first propose a data mining driven approach to prune the search space of bitmap join index selection problem. As opposed to an existing our technique that only uses frequency of attributes in queries as a pruning metric, our technique uses not only frequencies, but also other parameters such as the size of dimension tables involved in the indexing process, size of each dimension tuple, and page size on disk. We then define a greedy algorithm to select bitmap join indices that minimize processing cost and verify storage constraint. Finally, in order to evaluate the efficiency of our approach, we compare it with some existing techniques.

• Journal of KIISE:Databases
• /
• v.32 no.1
• /
• pp.1-11
• /
• 2005

An aggregation query computes aggregate information over a data cube in the query range specified by a user Existing methods based on the prefix-sum approach use an additional cube called the prefix-sum cube(PC), to store the cumulative sums of data, causing a high space overhead. This space overhead not only leads to extra costs for storage devices, but also causes additional propagations of updates and longer access time on physical devices. In this paper, we propose a new prefix-sum cube called 'SPEC' which drastically reduces the space of the PC in a large data warehouse. The SPEC decreases the update propagation caused by the dependency between values in cells of the PC. We develop an effective algorithm which finds dense sub-cubes from a large data cube. We perform an extensive experiment with respect to various dimensions of the data cube and query sizes, and examine the effectiveness and performance ot our proposed method. Experimental results show that the SPEC significantly reduces the space of the PC while maintaining a reasonable query performance.

• Journal of Korean Society of Rural Planning
• /
• v.24 no.4
• /
• pp.15-25
• /
• 2018

This study was designed to understand the change of rural landscape and to consider problems followed by development restrictions lifted for Neobiul Village in Ansan City, Korea. Physical landscape changes were comprehended by a field study and interview with local residents, and the residents' perception regarding the landscape changes were analyzed with the REP investigation method. The results can be summarized into the following three points: First, due to the lift of development restrictions and the deregulation of land use, the number of factories and warehouses for rent increased, which became a new source of income for the village. Second, the residents' complaints increased due to the increased traffic volume and waste from a sudden influx of factories and warehouses, which could not be handled by a small farming village. Third, a mix of landscape combining both city and farming village was formed due to the influx of external capital and the need of rental income, although the residents rather wanted Neobiul Village to become a residential village than a factory location. Furthermore, even in the farmlands near the village where development restrictions have not been lifted, the level of dependence on the farming industry has decreased as a consequence of the increase in farmland rent and weekend farms. This paper confirmed that the change of rural landscape followed by lifted development restrictions affects the everyday life of residents living in Neobiul Village. This study has significant implications in that it suggests a case showing the effects of national policies such as lifting development restrictions for rural villages in suburban areas.

• KIPS Transactions on Computer and Communication Systems
• /
• v.11 no.9
• /
• pp.281-288
• /
• 2022

AGVs are often used in industrial applications to transport heavy materials around a large industrial building, such as factories or warehouses. In particular, in fulfillment centers their usefulness is maximized for automation. To increase productivity in warehouses such as fulfillment centers, sophisticated path planning of AGVs is required. We propose a scheme that can be applied to QMIX, a popular cooperative MARL algorithm. The performance was measured with three metrics in several fulfillment center layouts, and the results are presented through comparison with the performance of the existing QMIX. Additionally, we visualize the transport paths of trained AGVs for a visible analysis of the behavior patterns of the AGVs as heat maps.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
• /
• 2021.11a
• /
• pp.101-103
• /
• 2021

With the rapid increase in the quantity of goods transported worldwide, companies are now started to show great interest in unmanned automated warehouses along with related research and development due to the increase of warehouse efficiency and reduction warehouse manpower. In a number of small warehouses, shuttle rack-based layouts that can handle inventory flow flexibly. However, the shuttle rack-based logistics center does not operate in case of emergency situations (faults, power outages, etc.), which seriously affects the efficiency and inventory management of the entire logistics center. Accordingly, in shuttle rack-based logistics center, we have classified various shuttle passages and RTV passages by layout and have analyzed its characteristics and types, along with derived reliability for each layout. The loading rate was also derived differently according to the number of passages, and have compared and analyzed reliability and loading rate for each layout.

• Journal of the military operations research society of Korea
• /
• v.11 no.1
• /
• pp.8-32
• /
• 1985

The objective of this study is to develop the Transportation Model of Linear Programming in which optimal transportation pattern by regions (origins and destinations) to minimize the total transportation costs can be obtained for handling government-held grains. As a result of computing the Transportation Model, the total transportation costs of transporting 1,058,507 metric tons from origins to destinations are 7,234 million won. So, the transporation cost is 6,834 won per ton in this model. But actual transportation cost in 1983 is 11,498 won per ton. Therefore when we distribute and transport the government-held grains from production factories to consumption warehouses, using this Transportation Model of Linear Programming is benefitable. Especially excluding the cost of computer, we could save more than two billion won of Government budget per year.

• Proceeding of Spring/Autumn Annual Conference of KHA
• /
• 2006.11a
• /
• pp.452-455
• /
• 2006

The purpose of this study is to investigate tendencies on land use by grasping the characteristics of changes of use at the borders of single-detached housing area for planning single-detached housing area in the future. It is divided the borders of detached housing areas into three types, educational facility, parks and green spaces, and apartment complex, and then analyzed the characteristics of each location after a field study. It is summarized as follows. First, warehouses and vacant sites were distributed in adjacent borders near parks and green areas. Second, there were stationery and flour-based meal stores in adjacent borders near educational facilities, suitable for students' interest and motion patterns. Third, there were realty dealers, food stores, and laundries which provide the dwellers with service in adjacent borders near multi-family housing.