• Proceedings of the Korean Geotechical Society Conference
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• 2008.03a
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• pp.1075-1082
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• 2008

Recently, coal ashes which are increasing annually are buried in ash ponds as industrial wastes. However, buried coal ashes can pollute ground water and ground due to leachate from coal ashes, which are serious environmental problem. Even though a lot of researches on recycling of coal ashes have been conducted, only 15% of coal ashes are recycled up to now. And those recycled coal ashes are not bottom ashes but fly ashes. So in this study, it was proved that Bottom Ash can be used as an alternative material to O.P.C(Ordinary Portland Cement) according to laboratory test results and test field construction. Also bottom ash is more economical and environmentally friendly than O.P.C.

• KEPCO Journal on Electric Power and Energy
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• v.8 no.2
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• pp.97-101
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• 2022

In this study we investigated the gas to solid heat transfer of bubbling fluidized bed bottom ash cooler installed at the Donghae power plant in South Korea. Several different analyses are done through 1-D calculations and 3-D CFD simulation to predict the bottom ash exit temperatures when it exits the ash cooler. Three different cases are set up to have consideration of unburnt carbon in the bottom ash. Sensible heat comparison and heat transfer calculation between the fluidization air and the bottom ash are conducted and 3-D CFD analysis is done on three cases. We have obtained the results that the bottom ash with unburnt carbon is exiting the ash cooler, exceeding the targeted temperature from both 1-D calculation and 3-D CFD simulation.

• Informatization Policy
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• v.19 no.3
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• pp.36-49
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• 2012

Internet Corporation for Assigned Names and Numbers (ICANN) is the body which manages the allocation and registration of global Internet IP addresses and domain names. As a gesture to overcome the dependency on the U.S. government, ICANN and the U.S. Department of Commerce jointly made the Affirmation of Commitment in which they submitted the workings of ICANN to the supervision of a council of Internet experts. Accountability and Transparency Review Team (ATRT) is one of four teams created for this purpose. In December 2010, ATRT made 27 recommendations, which were subsequently approved by the ICANN Board. These reform efforts of ICANN provide significant implications for the future of Korean Internet governance. Korea should enhance the compatibility of its domestic decision making process related to Internet addresses with the private sector driven, bottom-up process of global Internet governance. In order to increase the involvement of private sector and civil society, it is recommended for Korea to formalize the mechanism for bottom-up process. Insertion of a new provision concerning a bottom-up process into the Internet Addresses Act should be considered.

• Journal of Korea Port Economic Association
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• v.34 no.1
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• pp.65-80
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• 2018

This paper attempts to estimate GHG emissions, primarily $CO_2$ ship emissions, at the port of Incheon in October 2014. This study employed a bottom-up approach based on Automatic Identification System (AIS) data to estimate the total amount of fuel consumption and the total amount of $CO_2$ emission produced as a result of fuel combustion. Using a sample of 330 ships operating at the port of Incheon in Korea, the total amount of $CO_2$ gases emitted from ships in October 2014 were estimated to be 164693.06 tons, with estimated total fuel consumption of 51953.64 tons. General cargo ships were most common type of ships, but they were less polluting compared to passenger ships. The detailed emission estimates by ship type revealed that passenger ships were the most polluting ships (81409.6 tons of emissions), followed by tugboats (37248.4 tons), cargo ships (32154.6 tons), ships used for other activities (9039.1 tons), chemical tankers (4027.06 tons), and fishing ships (814.048 tons), respectively.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.15 no.2
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• pp.137-146
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• 1990

A series of images whose sized and resolutions differ by a constant factor are called an image pyramid. Because the images at high levels are small, large object can be detected on high levels of the pyramid at low cost, But in this way, the boundaries of objects are not accurately localized. Therefore the pyramid algorithms extracte the objects by segmentation the constructed image using bottom-up method and description it in an original resolution using inverse bottom-up method. In this paper, we can project an object down to the next lower level of the pyramid and apply to the boundary adjustment algorithm at that level to localize it more precisely. We repeat the process at successively lower levels. In this paper, we present a method of boundary adjustment using an image pyramid to obtain optimal boundary. The performance of the proposed algorithm is compared to those of the conventional method in term of subjective quality of object boundary.

• The Journal of Engineering Geology
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• v.29 no.3
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• pp.201-209
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• 2019

Bottom-up multi-stage pressure grouting is widely applied to domestic slopes and tunnels. It involves injecting earth from the ground to the surface after drilling. Various reports of construction performance have demonstrated its wide applicability. However, little research has studied top-down multi-step pressure grouting in Korea, which involves injection from the surface. This paper compares the grouting effect of both the established bottom-up method and the top-down method in soil box and field tests. The soil box test showed that the bulb volume of the top-down method is ~24% less than that of the bottom-up method. The field test confirmed that the top-down method has a wider grouting range and a higher injection density per area than the bottom-up method.

• Proceedings of the Korea Water Resources Association Conference
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• 2022.05a
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• pp.153-153
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• 2022

Large-scale and accurate observations at fine spatial resolution through a means of remote sensing offer an effective tool for capturing rainfall variability over the traditional rain gauges and weather radars. Although satellite rainfall products (SRPs) derived using two major estimation approaches were evaluated worldwide, their practical applications suffered from limitations. In particular, the traditional top-down SRPs (e.g., IMERG), which are based on direct estimation of rain rate from microwave satellite observations, are mainly restricted with their coarse spatial resolution, while applications of the bottom-up approach, which allows backward estimation of rainfall from soil moisture signals, to novel high spatial resolution soil moisture satellite sensors over South Korea are not introduced. Thus, this study aims to evaluate the performances of a state-of-the-art bottom-up SRP (the self-calibrated SM2RAIN model) applied to the C-band SAR Sentinel-1, a statistically downscaled version of the conventional top-down IMERG SRP, and their integration for a targeted high spatial resolution of 0.01° (~ 1-km) over central South Korea, where the differences in climate zones (coastal region vs. mainland region) and vegetation covers (croplands vs. mixed forests) are highlighted. The results indicated that each single SRP can provide plus points in distinct climatic and vegetated conditions, while their drawbacks have existed. Superior performance was obtained by merging these individual SRPs, providing preliminary results on a complementary high spatial resolution SRP over central South Korea. This study results shed light on the further development of integration framework and a complementary high spatial resolution rainfall product from multi-satellite sensors as well as multi-observing systems (integrated gauge-radar-satellite) extending for entire South Korea, toward the demands for urban hydrology and microscale agriculture.

• Journal of KIISE:Databases
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• v.29 no.5
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• pp.367-380
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• 2002

Due to recent increase in applications requiring huge amount of data such as spatial data analysis and image analysis, clustering on large databases has been actively studied. In a hierarchical clustering method, a tree representing hierarchical decomposition of the database is first created, and then, used for efficient clustering. Existing hierarchical clustering methods mainly adopted the bottom-up approach, which creates a tree from the bottom to the topmost level of the hierarchy. These bottom-up methods require at least one scan over the entire database in order to build the tree and need to search most nodes of the tree since the clustering algorithm starts from the leaf level. In this paper, we propose a novel top-down hierarchical clustering method that uses multidimensional indexes that are already maintained in most database applications. Generally, multidimensional indexes have the clustering property storing similar objects in the same (or adjacent) data pares. Using this property we can find adjacent objects without calculating distances among them. We first formally define the cluster based on the density of objects. For the definition, we propose the concept of the region contrast partition based on the density of the region. To speed up the clustering algorithm, we use the branch-and-bound algorithm. We propose the bounds and formally prove their correctness. Experimental results show that the proposed method is at least as effective in quality of clustering as BIRCH, a bottom-up hierarchical clustering method, while reducing the number of page accesses by up to 26～187 times depending on the size of the database. As a result, we believe that the proposed method significantly improves the clustering performance in large databases and is practically usable in various database applications.

• Advances in concrete construction
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• v.6 no.4
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• pp.407-422
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• 2018

The study evaluates properties of brick having coal ash and explores the possibility of utilization of coal bottom ash and coal fly ash as an alternative raw material in the production of coal ash bricks. Lower cement content was used in the investigations to attain appropriate strength and prohibit high carbon content that is cause of environmental pollution. The samples use up to 7% of cement whereas sand was replaced with bottom ash. Bricks were tested for compressive strength, modulus of rupture, ultrasonic pulse velocity (UPV), water absorption and durability. The results showed mix proportions of bottom ash, fly ash and cement as 1:1:0.15 i.e., M-15 achieved optimum values. The coal ash bricks were well bonded with mortar and could be feasible alternative to conventional bricks thus can contribute towards sustainable development.

• Journal of Agricultural Extension & Community Development
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• v.15 no.1
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• pp.145-175
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• 2008

This study has been carried out in order to examine the characteristics and rationales of the rural development policies of the President Roh Moo-Hyun's 'Participatory Government. The study is summarized into two different directions: characterization and rationalization. Characteristics of the government's rural development policies during the President Roh Moo-Hyun's 'Participatory Government (2003-2008) were three folds. First, the government has been more concerned with rural income level problems than those of living-environment standards. Second, the effect of the government's rural development policies has depended heavily upon both 'green tourism' and 'regional renovation'. Third, it has emphasized the applications of bottom-up approach particularly. This study found out a couple of problems about the rationales of the recent rural development policies; First, the developmental potentials and effects of policy measures which designate the rural green tourism, the regional renovation, and the bottom-up approach etc. were all over-estimated. Second, the structure of recent rural development policies was not vivid enough. Policy targets and measures have been proposed very vaguely; therefore, they have caused difficulties in identifying the actual feasibility and appropriateness of the rural development policies.