• Journal of KIISE:Databases
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• v.29 no.6
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• pp.502-512
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• 2002

Most of previous replication schemes assume lazy schemes, which asynchronously propagate replica updates to other nodes after the updating transaction commits. While lazy schemes are novel in the sense that they can resolve high deadlock frequencies of eager schemes, they suffer from the fact that users should be responsible for the data consistency. Recently replication schemes based on the messaging order of group communication have been studied. They can reduce the deadlock frequencies using the messaging order, but they have another problem of increasing execution overhead of aborted transactions at high degree of concurrency. This is because the sender node validates global serializability after multicasting replica update messages to other nodes. In this paper, we propose an efficient eager replication scheme for reducing the number of messaging and overhead of aborted transactions significantly. The proposed scheme validates any conflicts before multicasting and does not multicast when there is any conflict; hence, it can exploit performance improvement by alleviating the message traffic for replica update or by reducing the number of disk accesses and locking delay due to aborted transactions.

• Journal of KIISE:Databases
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• v.29 no.6
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• pp.500-500
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• 2002

Most of previous replication schemes assume lazy schemes, which asynchronously propagate replica updates to other nodes after the updating transaction commits. While lazy schemes are novel in the sense that they can resolve high deadlock frequencies of eager schemes, they suffer from the fact that users should be responsible for the data consistency. Recently replication schemes based on the messaging order of group communication have been studied. They can reduce the deadlock frequencies using the messaging order, but they have another problem of increasing execution overhead of aborted transactions at high degree of concurrency. This is because the sender node validates global serializability after multicasting replica update messages to other nodes. In this paper, we propose an efficient eager replication scheme for reducing the number of messaging and overhead of aborted transactions significantly. The proposed scheme validates any conflicts before multicasting and does not multicast when there is any conflict; hence, it can exploit performance improvement by alleviating the message traffic for replica update or by reducing the number of disk accesses and locking delay due to aborted transactions.

• Proceedings of the Korean Information Science Society Conference
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• 2002.10c
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• pp.403-405
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• 2002

본 논문은 Recovery 기법 중의 하나인 Roll-Forward를 적용한 고가용 웹 서버의 설계 및 구현에 대해서 그 방안을 제시한다. Roll-Forward Recovery 는 복구에 드는 시간을 감소시킬 수 있다는 장점이 있다. 즉, 일반적인 중복 시스템에서 결함이 발생하면 시스템의 상태는 가장 최근의 checkpoint 지점으로 Rollback 되어야 하기 때문에 복구에 많은 시간을 소비하게 되지만, Roll-Forward를 적용함으로써 복구에 드는 시간을 감소시킬 수 있다. 단일 서버시스템 또는 Rollback Recovery를 적용한 시스템의 결함 발생 시 서비스를 제공할 수 없는 상태가 되거나 복구에 많은 시간을 소비한다. 이에 비해 Roll-Forward를 적용한 중복 서버시스템을 구성하여 동작 운용중인 서버의 결함 발생 시 즉시 다른 서버가 결과를 보여줌으로써 고가용 웹 서비스를 제공할 수 있다. 본 논문에서 제시하는 Roll-Forward를 적용한 고가용 웹 서버의 동작원리는 마스터서버에 들어오는 요청을 백업서버에서도 똑같이 수행하며, 마스터 서버가 동작 중 결함이 발생하였을 경우 백업서버가 피 결과를 보여줌으로써 고가용의 서비스가 제공되는 웹 서버를 구현하고자 한다.

• Spatial Information Research
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• v.6 no.1
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• pp.65-76
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• 1998

Air contaminant density must be inferred exactly to manage air pollution. Each land use of air pollution source is duplicated in the existing air contaminant distribution because the resolution of the land use map is low. The purpose of this study is to understand how the land use map is used to determine effectively in the distribution calculation of the emission volume and the inference of air contaminant density, as it is made in a high resolution. The major findings are as follows : In this study, as to making a high resolution($28.5m{\times}28.5m$) map of land use with GIS, each air pollution source is not duplicated spatially and land use can be reflected effectively. In Seoul, each air contaminant density was inferred (using a TCM-2 model) with the existing distribution map of emission volume, whose resolution is $1km{\times}1km$, and the new distribution map of emission volume, whose resolution is $28.5km{\times}28.5km$. According to the result, the inference value of the new distribution map was more similar to the actual value of an automatic survey network.

• Proceedings of the Korea Institutes of Information Security and Cryptology Conference
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• 1997.11a
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• pp.439-459
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• 1997

본 논문에서는 전자 문서 교환 시스템인 EDI에서의 정보보호 서비스를 제공하는 EDI 정보보호 시스템의 개발 기술에 대하여 언급한다. 이 시스템은 주로 ITU-TX.400 MHS 통신 프로토콜에 기반을 둔 X.435 EDI 정보보호 서비스를 제공함에 그 목적을 두고 있다. 본 논문에서는 정보보호 서비스 처리 시 발생하는 중복되는 작업을 최소화하고 사용 알고리즘을 언제든지 교체 또는 변경할 수 있는 시스템 구조와 기존 EDI시스템의 최소변경만으로 정보보호 시스템 구축이 가능토록 하는 이식성을 극대화하는 정보보호 시스템 모델과 관리 방안을 제시하였다.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.13 no.22
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• pp.59-64
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• 1990

This paper is aimed to study the standby redundant system with the relay of parallel structure, by making use of the character of standby system, which reliability is higher than parallel system's if the relay has higher reliability than a certain level. By assigning the low-priced relay to the subsystem, this method increases the relay reliability, optimizes the standby redundant system reliability without violating the restrictions, and consequently reduces the cost.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.13 no.9
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• pp.1955-1963
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• 2009

In the application of wireless sensor networks to monitor valuable assets under concern, the appearance of a certain asset can be identified and reported simultaneously by several adjacent nodes, and this may dissipate the power of related nodes and network bandwidth as well. In the proposed method, a node that senses the appearance of some asset is allowed to send the sensing-reporting packet only after it has been being idle for a certain period without receiving any DRP(Don't Report Packet) from neighbors. It turns out that not only the cost of propagating DRPs but also that of reporting the events to the sink becomes minimal when depth of each DRP propagation is 2. In case of depth 1, at least, two routes are set up for the delivery of the sensing-reporting packet hence, reliable transfer to the sink is provided.

• Composites Research
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• v.23 no.6
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• pp.32-38
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• 2010

The effect of the atmospheric pressure plasma(APP) treatments is experimentally investigated to ascertain the optimum condition to yield the best adhesive properties between a polyamide woven fabric and acrylonitrile butadiene rubber(NBR). For the atmospheric pressure flame plasma(APFP) treatment, the optimum number of treatment at given conditions is 2 times. The thermal deformation of the fabric is more serious with increasing the number of APFP treatment. The adhesive strength of the case with APFP treated fabric is increased about 35% when compare to the case with non-APFP treated one for the interface(bonding agent one or two coatings). When the surface is coated twice with the bonding agent, the adhesive energy with APFP treated fabric is increased about 4 times. It was found that the surface modification of polyamide woven fabric by APFP treatment is a fast, economic and applicable method to improve the adhesive properties between woven fabric and rubber when compared to other APP treatments.

• Journal of Environmental Impact Assessment
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• v.25 no.6
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• pp.532-541
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• 2016

The National Environmental Specimen Bank (NESB) has been collecting broad leave samples to monitor environmental pollution from five different designated sampling areas. In order to ensure the reproducibility and comparability of the results, all the procedures from selecting trees and pooling leaves to make the representative sample are defined in the standard operation procedures(the SOP). The representative samples were subjected to the chemical analyses for some heavy minerals and Polycyclic Aromatic Hydrocarbons(PAHs). The uncertainty levels involved in each step of the SOP, that is, the sampling and the chemical analysis, were derived using the Robust ANOVA, which enables the relative comparison among the different levels of pollutants concentrations with confidence. Furthermore, the effect of the varying degrees of precipitation on the pollutants concentration of the leaves was also examined. Overall, the biological difference estimated from the duplicate samples was found to exceed the variation across the site, implying even aerial deposition over site. Samples from Gwanak Mt. showed highest heavy metal concentrations than the other sites. Washing off effect of the pollutants adhering in the form of particles on the leaf surface was found to be affected by the cumulative precipitation.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.13 no.4
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• pp.1931-1938
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• 2012

This study evaluated whether the installed location of air quality monitoring stations is at an optimal level in an effort to improve the health and environmental quality of the surrounding areas of the Pohang Steel Complex. As a result of analyzing the atmospheric flow field, it was found that the location of air quality monitoring stations was acceptable in case of Daesong-myeon(The 1st Division of Local Wind Sector) and Jukdo-dong(The 3rd Division of Local Wind Sector). However, the air quality monitoring stations installed at Daedo-dong and Jukdo-dong is judged to have made an overlapped measurement because the stations existed at the Division of the same Wind Sector. Accordingly, this study suggests that the further air quality monitoring stations should be additionally installed at Buk-gu areas of Pohang where more than 50% of the population of Pohang is living presently. As a result of the analysis of air contaminant concentration distribution, the Jangheung-dong area showed higher concentration distribution than other areas in case of $PM_{10}$ while the Daesong-myeon area showed a comparatively higher concentration distribution in case of $O_3$. Conclusively, this study indicates that it is high time to prepare an aggressive management of $PM_{10}$ and $O_3$ which causes a harmful impact on the life and health of the residents of the target areas.