• Journal of the Korea Society of Computer and Information
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• v.12 no.6
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• pp.49-57
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• 2007

The P2P distributed systems are proceeded various studies lively to use the idleness computing resources under the network connected computing environments. It's a general mean to communication from the peer of the shortest downloaded time among same target files to be searched. The P2P search algorithms are very important primary factor to decide a real downloaded time in the criteria to select the peer of a shortest downloaded time. However the peer to give resources could be changed into offline status because the P2P distributed systems have very weakness connection. In these cases. we have a choice to retransmit resources mainly. In this study, we suggested an effective backtracking search algorithm to improve the performance about the request to retransmit the resource.

• Journal of the Korean earth science society
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• v.40 no.2
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• pp.177-187
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• 2019

Several volcanic activities have continued in Mt. Baekdu since the Millennium eruption, and these phenomena have increased the need for volcanic activity surveillance. Various geophysical approaches are needed to obtain the depth and size of magma chamber that lie several kilometers below the surface. We examined the applicability of direct-current resistivity survey in this study. In order to explore the deep magma chamber of Mt. Baekdu, which has a spatial limitation due to the borderline, a large-scale survey with a length of tens of kilometers should be conducted. This type of survey requires a distributed measurement system and optimized exploration designs. Therefore, we propose survey designs taking advantage of our developed distributed acquisition system and analyze the applicability using numerical simulation. We confirmed that our designs that use single survey line with offline transmitting points show comparable results to the conventional 3D survey. It is expected that our research result can contribute to the deep geophysical exploration in Mt. Baekdu.

• Journal of Korea Water Resources Association
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• v.43 no.7
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• pp.667-679
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• 2010

The distributed hydrologic model has been considerably improved due to rapid development of computer hardware technology as well as the increased accessibility and the applicability of hydro-geologic information using GIS. It has been acknowledged that physically-based distributed hydrologic model require significant amounts of data for their calibration, so its application at ungauged catchments is very limited. In this regard, this study was intended to develop a distributed hydrologic model (S-RAT) that is mainly based on conceptually grid-based water balance model. The proposed model shows advantages as a new distributed rainfall-runoff model in terms of their simplicity and model performance. Another advantage of the proposed model is to effectively assess spatio-temporal variation for the entire runoff process. In addition, S-RAT does not rely on any commercial GIS pre-processing tools because a built-in GIS pre-processing module was developed and included in the model. Through the application to the two pilot basins, it was found that S-RAT model has temporal and spatial transferability of parameters and also S-RAT model can be effectively used as a radar data-driven rainfall-runoff model.

• Proceedings of the Korea Water Resources Association Conference
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• 2005.05b
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• pp.143-148
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• 2005

The main purpose of this study is to suggest and evaluate an operational method for assessing the potential impact of climate change on hydrologic components and water resources of regional scale river basins. The method, which uses large scale climate change information provided by a state of the art general circulation model(GCM) comprises a statistical downscaling approach and a spatially distributed hydrological model applied to a river basin located in Korea. First, we construct global climate change scenarios using the YONU GCM control run and transient experiments, then transform the YONU GCM grid-box predictions with coarse resolution of climate change into the site-specific values by statistical downscaling techniques. The values are used to modify the parameters of the stochastic weather generator model for the simulation of the site-specific daily weather time series. The weather series fed into a semi-distributed hydrological model called SLURP to simulate the streamflows associated with other water resources for the condition of $2CO_2$. This approach is applied to the Yongdam dam basin in southern part of Korea. The results show that under the condition of $2CO_2$, about $7.6\% of annual mean streamflow is reduced when it is compared with the observed one. And while Seasonal streamflows in the winter and autumn are increased, a streamflow in the summer is decreased. However, the seasonality of the simulated series is similar to the observed pattern and the analysis of the duration cure shows the mean of averaged low flow is increased while the averaged wet and normal flow are decreased for the climate change.

• Korean Journal of Plant Taxonomy
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• v.43 no.3
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• pp.165-167
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• 2013

Five taxa of the genus Ajuga L. (Lamiaceae) were known previously in Korea which were mainly distributed in lowland and lower montane areas at 50-1000 m elevation. We report an unrecorded taxon of the genus Ajuga in Korea, namely Ajuga nipponensis Makino. This taxon was discovered at Is. Nok, Boryeong-si, in Chungcheongnam Province. A. nipponensis is found to be distributed along roadsides near villages of the island. A. nipponensis was distinguishable from other Ajuga in Korea by following combination of characters: Stems erect or procumbent, arranged in a dense cluster, corolla whitish-pale pink, 10-12 mm long. This taxon was named 'Bun-hong-kkot-jo-gae-na-mul' in Korean based on color of the corolla. The key to the genus Ajuga in Korea is also provided.

• The KIPS Transactions:PartC
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• v.12C no.7 s.103
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• pp.1015-1024
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• 2005

A delegation of privileges is one of important processes that empower authority to relevant node to process job that user wants in large-stale distributed environment such as Grid Computing. However, existing delegation methods do not give suitable privilege about Job, and do not atomize range of delegation and exists delegation of access privilege for only resources itself that is not delegation about executing process of job itself. Also, they do not apply about process that needs delegation before and after. execution of job such as reservation of system resources or host access before and after execution. Therefore, this paper proposes a method and specification for restricted delegation in distributed environment. Proposed method separates delegation for job side and privilege side, and express specification and procedure of delegation using XML schema and UML and present restricted delegation scenario in distributed computing environment.

• Journal of Korea Water Resources Association
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• v.42 no.3
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• pp.247-257
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• 2009

In this study, a distributed rainfall-runoff model is developed using a multi-directional flow allocation algorithm and the real-time runoff updating algorithm. The developed model consists of relatively simple governing equations of hydrologic processes in order to apply developed algorithms and to enhance the efficiency of computational time which is drawback of distributed model application. The variability of topographic characteristics and flow direction according to various spatial resolution were analyzed using DEM(Digital Elevation Model) data. As a preliminary process using fine resolution DEM data, a multi-directional flow allocation algorithm was developed to maintain detail flow information in distributed rainfall-runoff simulation which has strong advantage in computation efficiency and accuracy. Also, a real-time updating algorithm was developed to update current watershed condition. The developed model is able to hold the information of actual behavior of runoff process in low resolution simulation. Therefore it is expected the improvement of forecasting accuracy and computational efficiency.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.65 no.2
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• pp.239-246
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• 2016

In recent years, the power demand has been increasing steadily and the occurrence of maximum power demand has been moving from the summer season to the winter season in Korea. And since the control of electric power supply and demand is more important under those situations, a micro-grid system began to emerge as a keyword for the sTable operation of electric power system. A micro-gird power system is composed of various kinds of distributed generators(DG) such as small diesel generator, wind turbine, photo-voltaic generator and energy storage system(ESS). This paper introduces a method to determine the optimal capacities of the distributed generators which are installed in a stand-alone type of microgrid power system based on the fundamental proportion of diesel generator. At first, the fundamental proportion of diesel generator will be determined by changing from 0 to 50 percent. And then we will optimize the capacities of renewable energy resources and ESS according to load patterns. Lastly, after recalculating the capacity of ESS with consideration for SOC constraints, the optimal capacities of distributed generators will be decided.

• The Journal of Bigdata
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• v.7 no.1
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• pp.1-14
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• 2022

The proof-of-work consensus algorithm used by most blockchains is causing a massive waste of computing resources in the form of mining. A useful proof-of-work consensus algorithm has been studied to reduce the waste of computing resources in proof-of-work, but there are still resource waste and mining centralization problems when creating blocks. In this paper, the problem of resource waste in block generation was solved by replacing the relatively inefficient computation process for block generation with distributed artificial intelligence model learning. In addition, by providing fair rewards to nodes participating in the learning process, nodes with weak computing power were motivated to participate, and performance similar to the existing centralized AI learning method was maintained. To show the validity of the proposed methodology, we implemented a blockchain network capable of distributed AI learning and experimented with reward distribution through resource verification, and compared the results of the existing centralized learning method and the blockchain distributed AI learning method. In addition, as a future study, the thesis was concluded by suggesting problems and development directions that may occur when expanding the blockchain main network and artificial intelligence model.

• Journal of Integrative Natural Science
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• v.16 no.4
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• pp.139-145
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• 2023

Due to changes in the distribution system and increased demand for renewable energy, interest in technology to increase the limit capacity of distributed energy grid connection using grid flexible resources is also increasing. Recently, the distribution system system is changing due to the increase in distributed power from renewable energy, and as a result, problems with the limited capacity of the distribution system, such as waiting for renewable energy to connect and increased overload, are occurring. According to the power generation facility status report provided by the Korea Power Exchange, of the total power generation capacity of 134,020 MW as of 2021, power generation capacity through new and renewable energy facilities is 24,855 MW, accounting for approximately 19%, and among them, power generation through solar power accounts for a total portion of the total. It was analyzed that the proportion of solar power generation facilities was high, accounting for 75%. In the future, the proportion of new and renewable energy power generation facilities is expected to increase, and accordingly, an efficient operation plan for the distribution system is needed. Advanced country-type NWAs that can integrate the operation and management of load characteristics for each line of the distribution system, power distribution, regional characteristics, and economic feasibility of distributed power in order to improve distribution network use efficiency without expanding distribution facilities due to the expansion of renewable energy. An integrated operating system is needed. In this study, in order to improve the efficiency of distribution network use without expanding distribution facilities due to the expansion of renewable energy, we developed a method that can integrate the operation and management of load characteristics for each line of the distribution system, power distribution, regional characteristics, and economic feasibility of distributed power. We want to develop an integrated operation system for NWAs similar to that of advanced countries.