• The Journal of Society for e-Business Studies
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• v.14 no.3
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• pp.169-181
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• 2009

As the situations that important evidences or clues are found in digital information devices increase, digital forensic technology is widely applied. In this paper, forensic based audit system is implemented by associating forensic analysis system with agent system which monitors and collects data for analysis in storage devices over distributed network nodes. Forensic audit system implemented in this paper can prevent, audit and trace the computer related crimes in IT infrastructure by real time monitoring and evidence seizure.

• Proceedings of the Korea Information Processing Society Conference
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• 2009.11a
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• pp.111-112
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• 2009

최근 IT 분야의 키워드 중 하나인 클라우드 컴퓨팅에서, 분산 파일 시스템의 선택은 대용량의 데이터를 관리하기 위해 매우 중요하다. 오픈소스 분산 파일 시스템 중 하나인 HDFS는 데이터의 효율적인 저장과 검색의 장점을 통해 최근 널리 사용되고 있다. HDFS는 데이터를 3단계 중복저장을 통해 신뢰성을 보장한다. 그러나 이러한 중복저장은 데이터 저장의 효율성 저하의 문제점을 갖고 있다. 따라서 본 논문에서는 MD5 해쉬 기술을 적용한 중복 데이터 제거 기법을 제안한다. 본 기법은 시뮬레이션을 통해 저장 공간의 효율성을 향상의 결과를 확인하였다.

• Journal of KIISE:Computer Systems and Theory
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• v.31 no.9
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• pp.503-513
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• 2004

In large distributed systems, replications of data and service are needed to decrease communication cost, increase availability, and avoid single server bottleneck. Tree Quorum protocol is a representative replication protocol, which exploits a logical structure. Tree quorum protocol is one of the replication protocols allowing low read cost only in the best case, while the number of replicas exponentially increases as the level grows. In this paper, thus, we propose a new replication protocol, called symmetric tree protocol which efficiently solves the problem. The proposed symmetric tree protocol also requires much smaller read cost than previous protocols. We conduct cost and availability analysis of the protocols, and the proposed protocol displays comparable read availability to the tree protocol using much smaller number of nodes. Also, the symmetric tree protocol has much smaller response time than the logarithmic protocol.

• Korean Journal of Veterinary Research
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• v.39 no.5
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• pp.921-929
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• 1999

There have been a number of studies of gonadotropes secreting LH and FSH in the adenohypophysis, but the pattern of hormone storage and secretion of these cells still remains a controversial matter. In this study, we examined whether gonadotropes contained both of LH and FSH, and if so, how these hormones were distributed within the secretory granules. Hypophyseal sections of Korean native goat were simultaneously immunostained for LH and FSH antisera by protein A-gold technique. It was found that most gonadotropes contained both FSH and LH, but hormone storages in the secretory granules were some different among cells. Three types of gonadotropes were identified by the shape and size of the secretory granules and their hormone storage patterns. One type(I) of gonadotropes contained oval secretory granules, which immunoreactivity for FSH and LH were very weak. The size of secretory granules ranged from 160 to 310nm in diameter. Most granules contained both FSH and LH, but some contained only one of them. In another type(II) of gonadotropes, the immunreactivity and hormone storage patterns of the secretory granules were similar to those of type I cells. However, the secretory granules were round in shape and larger in size than those of type I. The other gonadotropes(type III) were distinctly distinguished by plenty of hormones in their secretory granules which were densely packed with numerous immunolabelled gold particles. These data are some inconsistent with other results that have been obtained in other ruminants like as cattle and sheep.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 1994.07a
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• pp.184-215
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• 1994

The Hydrogeologic data of 455 water wells comprising geologic and aquifer test were analyzed to determine hydrogeoloic characteristics of Cheju island. The groundwater of Cheju island is occurred in unconsolidated pyroclastic deposits interbedded in highly jointed basaltic and andesic rocks as high level, basal and parabasal types order unconfined condition. The average transmissivity and specific yield of the aquifer are at about 29,300m$^2$/day and 0.12 respectively. The total storage of groundwater is estimated about 44 billion cubic meters(m$^3$). Average annual precipitation is about 3390 million m$^3$ among which average recharge amount is estimated 1494 million m$^3$ equivalent 44.1% of annual precipitation with 638 million m$^3$ of runoff and 1256 million m$^3$ of evapotranspiration. Based on groundwater budget analysis, the sustainable yield is about 620 million m$^3$(41% of annual recharge)and rest of it is discharging into the sea. The geologic logs of recently drilled thermal water wens indicate that very low-permeable marine sediments(Sehwa-ri formation) composed of loosely cemented sandy sat derived from mainly volcanic ashes, at the 1st stage volcanic activity of the area was situated at the 120$\pm$68m below sea level. And also the other low-permeable sedimentary rock called Segipo-formation which is deemed younger than former marine sediment is occured at the area covering north-west and western part of Cheju at the $\pm$70m below sea level. If these impermeable beds are distributed as a basal formation of fresh water zone of Cheju, most of groundwater in Cheju will be para-basal type. These formations will be one of the most important hydrogeologic boundary and groundwater occurences in the area.

• Journal of KIISE:Databases
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• v.37 no.6
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• pp.315-323
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• 2010

In Wireless Sensor Networks (WSNs), various Data-Centric Storages (DCS) schemes have been proposed to store the collected data and to efficiently process a query. A DCS scheme assigns distributed data regions to sensor nodes and stores the collected data to the sensor which is responsible for the data region to process the query efficiently. However, since the whole data stored in a node will be lost when a fault of the node occurs, the accuracy of the query processing becomes low, In this paper, we propose an in-network aggregation query processing method that assures the high accuracy of query result in the case of data loss due to the faults of the nodes in the DCS scheme. When a data loss occurs, the proposed method creates a compensation model for an area of data loss using the linear regression technique and returns the result of the query including the virtual data. It guarantees the query result with high accuracy in spite of the faults of the nodes, To show the superiority of our proposed method, we compare E-KDDCS (KDDCS with the proposed method) with existing DCS schemes without the data-loss correction method. In the result, our proposed method increases accuracy and reduces query processing costs over the existing schemes.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.35 no.5
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• pp.1039-1049
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• 2015

The inflow estimation at large multipurpose dam reservoir is carried out by considering the water balance among the discharge, the storage change during unit time interval obtained from the observed water level near dam structure and area-volume curve. This method can be ideal for level pool reservoir but include potential errors when the inflow is influenced by the water level slope due to backwater effects from upstream flood inflows and strong wind induced by typhoon. In addition, the other uncertainties arisen from the storage reduction due to sedimentation after the dam construction and water level noise due to mechanical vibration transmitted from the electric power generator. These uncertainties impedes the accurate hydraulic inflow measurement requiring exquisite hydrometric data arrangement for reservoir waterbody. In this study, the distributed hydrologic model using UBC-3P boundary setting was applied and its feasibility was evaluated. Finally, the modeling performance has been verified since the calculated determination coefficient has been in between 0.96 to 0.99 after comparing with observed peak inflow and total inflow at Namgang dam reservoir.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.2
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• pp.434-442
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• 2019

Low Impact Development(LID) techniques has been attracting attention as a countermeasure to solve frequent flood damage in urban areas. LID is a techniques for returning to the natural hydrological cycle system by infiltrating the runoff from the impervious surface into the soil. The Bio-retention, one of the LID element technology has outflow reduction effect by reserving and infiltrating storm water runoff from watersheds. Recently, a number of studies have been carried out as interest in the reduction of storm water runoff and non-point pollutants in Bio-retention has increased. However, quantitative analysis on the outflow reduction of Bio-retention applied to small watershed is insufficient. In this study, Bio-retention model was constructed in a small watershed using K-LIDM which is capable of hydrologic analysis. When the storage capacity was increased or dividing the Bio-retention and watershed, the outflow reduction effect was 20% according to the storage capacity increase and 5~15% in the distributed Bio-retention system. The results of this analysis will be used as the basic data of future Bio-retention research related to watershed characteristics, vegetation type and soil condition.

• Journal of The Korean Association of Information Education
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• v.9 no.1
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• pp.79-86
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• 2005

With the rapid advance of computer and communication technology, the amount of data transferred is also increasing more than ever. The recent trend of education systems is connecting related information semantically in different systems in order to improve the utilization of computerized information Therefore, Web-based teaching-learning is developing in the ubiquitous learning direction that learners select and organize the contents, time and order of learning by themselves. That is, it is evolving to provide teaching-learning environment adaptive to individual learners' characteristics (their level of knowledge, pattern of study, areas of interest). This paper proposes the efficient evaluation method of learning contents in a mediator for the integration of heterogeneous information resources. This means that the autonomy of a remote server can be preserved to the highest degree. In addition, this paper proposes the adaptive optimization of learning contents such that available storage in a mediator can be highly utilized at any time. In order to differentiate the recent usage of a learning content from the past, the accumulated usage frequency of a learning content decays as time goes by.

• Journal of KIISE:Computer Systems and Theory
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• v.27 no.2
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• pp.188-199
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• 2000

This paper presents an efficient stable logging scheme for the distributed shared memory system based on the lazy release consistent memory model. In the proposed scheme, inter-process dependency is traced and stable logging is performed when the dependency relation between processes actually happens. With the dependency tracking, the proposed scheme requires much less frequency of stable logging, comparing with the previous schemes in which stable logging is performed whenever any information transfer happens between processes. Also, in the proposed scheme, every data item accessed by a process is not logged, but only the access information is logged in the stable storage. For the recovery from a failure, the correct version of the accessed data items can be effectively traced by using the logged access information. As a result, the amount of logged information is also reduced.