• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.10
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• pp.167-175
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• 2018

To cope with the increasing number of natural disasters in recent years, managers in the National Disaster and Safety Status Control Center, who have considerable experience and skills, are regarded highly important. Although the National Disaster and Safety Status Control Center oversees the disaster-status control tasks in preparation for various natural and social disasters, there is little data due to the frequent replacement of managers. Therefore, this study developed a disaster-safety code system that tracks and manages disaster information, because the current record management and amount of information sharing remains very low. Among 22 natural and social disaster types, this study targeted four types of disasters: heavy snow, strong winds, high seas, and heavy rain. The final disaster-safety data code system was proposed through the following processes: analysis of the code systems of disaster areas in Korea and overseas, setup of the implementation of directions, development of the classification system, and categorization. For the systematic accumulation of data, the four code systems were integrated into one. A prototype system was developed and operated to verify the validity of the proposed code system. The results showed that data were accumulated and services were provided accordingly with respect to the proposed code system. If past data are accumulated and utilized according to the proposed code system in this study, it will be helpful in the decision making process to respond to new types of disasters, based on past experiences.

• Resources Recycling
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• v.20 no.2
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• pp.16-29
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• 2011

The Korea auto industry has developed remarkedly over the past 40 years and ranked up to 5th vehicles production nation in the world. In 2009 alone, Korea produced 3.5million vehicles and number of vehicles registered surpassed the seventeen million. On the other hand, 711 thousand ELV(End of Life Vehicles) were scrapped and used cars more than 265 thousand were exported. In the year 2009, 568 thousand tons of iron, 46 thousand tons of aluminum and 7 thousand tons of copper were recovered from ELV in Korea. Recycling ratio of ELV is approaching 95% by using ASR(Automobile Shredding Residue) as a fuel at cement kiln. Korea has enacted the automobile recycling law in 2007 and enforced it from January 2009, actually. However, the law has not been managed smoothly due to delays in the construction of infrastructure and the existence of a hostile monitoring system. In this regard, a revision and supplement program focused on recycling fee on the automobile recycling law is running under the ministry of environment now. Here, a recycling model for enhancing ELV recycling is suggested.

• KIISE Transactions on Computing Practices
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• v.21 no.8
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• pp.524-530
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• 2015

A log is for text monitoring and perceiving the issues of a system during the development and operation of a program. Based on the log, system developers and operators can trace the cause of an issue. In the development phase, it is relatively simple for a log to be traced while there are only a small number of personnel uses of a system such as developers and testers. However, it is the difficult to trace a log when many people can use the system in the operation phase. In major cases, because a log cannot be tracked, even tracing is dropped. This study proposed a simplified tracing of a log during the system operation. Thus, the purpose is to create a log on the run time based on an ID/IP, using features provided by the Logback. It saves an ID/IP of the tracking user on a DB, and loads the user's ID/IP onto the memory to trace once WAS starts running. Before the online service operates, an Interceptor is executed to decide whether to load a log file, and then it generates the service requested by a certain user in a separate log file. The load is insignificant since the arithmetic operation occurs in a JVM, although every service must pass through the Interceptor to be executed.

• Journal of KIISE:Databases
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• v.35 no.3
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• pp.218-230
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• 2008

The temporal aggregate in temporal databases is an extension of the conventional aggregate to include the time on the range condition of aggregation. It is a useful operation for Historical Data Warehouses, Call Data Records, and so on. In this paper, we propose a structure for the temporal aggregation with multiple selection predicates, called the ITA-tree, and an aggregate processing method based on the structure. In the ITA-tree, we transform the time interval of a record into a single value, called the T-value. Then, we index records according to their T-values like a $B^+$-tree style. For possible hot-spot situations, we also propose an improvement of the ITA-tree, called the eITA-tree. Through analyses and experiments, we evaluate the performance of the proposed method.

• The KIPS Transactions:PartD
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• v.18D no.1
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• pp.1-8
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• 2011

The cache structure, which is designed for assuring fast accesses to frequently accessed data, resides on the various levels of computer system hierarchies. Many studies on this cache structure have been conducted and thus many page-replacement algorithms have been proposed. Most of page-replacement algorithms are designed on the basis of heuristic methods by using their own criteria such as how recently pages are accessed and how often they are accessed. This data-retrieval process in computer systems is analogous to human memory retrieval process since the retrieval process of human memory depends on frequency and recency of the retrieval events as well. A recent study regarding human memory cognition revealed that the possibility of the retrieval success and the retrieval latency have a strong correlation with the frequency and recency of the previous retrieval events. In this paper, we propose a novel page-replacement algorithm by utilizing the knowledge from the recent research regarding human memory cognition. Through a set of experiments, we demonstrated that our new method presents better hit-ratio than the LRFU algorithm which has been known as the best performing page-replacement algorithm for DBMS caches.

• Journal of the Korea Society of Computer and Information
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• v.25 no.7
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• pp.9-16
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• 2020

In this paper, we propose a prototype design and implementation of a fire detection algorithm using multiple sensors. The proposed topic detection system determines fire by applying rules based on data from multiple sensors. The fire takes about 3 to 5 minutes, which is the optimal time for fire detection. This means that timely identification of potential fires is important for fire management. However, current fire detection devices are very vulnerable to false alarms because they rely on a single sensor to detect smoke or heat. Recently, with the development of IoT technology, it is possible to integrate multiple sensors into a fire detector. In addition, the fire detector has been developed with a smart technology that can communicate with other objects and perform programmed tasks. The prototype was produced with a success rate of 90% and a false alarm rate of 10% based on 10 actual experiments.

• Proceedings of the Korea Water Resources Association Conference
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• 2012.05a
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• pp.479-483
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• 2012

최근 국내외에서 기상이변에 따른 물 부족에 대응하고 먹는 물의 생산과 공급 효율성 향상을 위하여 스마트워터그리드에 대한 연구가 활발히 진행되고 있는 경향으로 이는 상수도 인프라시설의 운영오류, 자연재해, 사이버를 통한 의도적 공격 등에 대해 안전하고 신뢰성이 높은 시스템을 구축하기 위한 것이다. 또한 상수도 분야에서는 스마트 미터링 개념을 도입하여 상수관망에서 발생되는 각종 사고나 물 손실을 저감하기 위한 노력이 시도되고 있는 실정이다. 일반적으로 누수량이 많을 경우에는 누수의 징후가 지표면에서 확인이 가능하나 미세한 경우 탐사장비의 운영이나 인력의 투입을 통해 가능하다. 물 공급계통인 상수관망에서 물 손실을 저감시키기 위한 방법중 하나로서 수도미터로부터 기록되는 물 사용량 데이터를 이용하여 누수패턴을 추출함으로써 누수감시가 가능하도록 하는 모형을 개발하고자 하였다. 이는 탐사장비에 의한 누수감지와 상호 보완적을 활용할 수 있는 것으로서 사용량 자료를 분석하여 사전에 처리된 자료의 노이즈와 결함 있는 계측값을 필터링시키는 기법이 도입된 것이며 신속한 감지를 통해 누수 지속시간을 감소시킴으로서 누수량의 저감을 목표로 한다. 물 공급 네트워크를 보다 더 효율적 만들 수 있는 누수 감시모형은 상수관망의 운영에 필요한 정보를 도출하기 위하여 보다 정확하고 다양한 수학적 및 통계적 분석을 기반으로 구성되어 누수 외에도 각종 결함을 찾아내는 역할을 수행할 수 있다. 향후 다양한 지역을 이러한 수용가의 물 사용량 미터링 결과를 토대로 실제 사용량과 누수량을 분리하여 분석함으로써 국내 실정에 적합한 누수감시 기술배발 토대를 마련할 수 있을 것으로 판단되며, 누수저감을 위한 실질적인 상수관망의 운영관리 효율향상의 정보로서 활용이 가능할 것으로 판단된다.

• Journal of KIISE:Computing Practices and Letters
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• v.15 no.2
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• pp.77-88
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• 2009

According to the size of NAND flash memory as the storage system of mobile device becomes large, the performance of address translation and life cycle management in FTL (Flash Translation Layer) to interact with file system becomes very important. In this paper, we propose the continuity counters, which represent the number of continuous physical blocks whose logical addresses are consecutive, to reduce the number of address translation. Furthermore we propose the prefetching method which preloads frequently accessed pages into main memory to enhance I/O performance of flash memory. Besides, we use the 2-bit write prediction and asynchronous writing method to predict addresses repeatedly referenced from host and prevent from writing overhead. The experiments show that the proposed method improves the I/O performance and extends the life cycle of flash memory. As a result, proposed CFTL (Clustered Flash Translation Layer)'s performance of address translation is faster 20% than conventional FTLs. Furthermore, CFTL is reduced about 50% writing time than that of conventional FTLs.

• The KIPS Transactions:PartA
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• v.15A no.6
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• pp.335-344
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• 2008

We propose an adaptive garbage collection technique for hybrid flash memory which has both SLC and MLC. Since SLC area is fast and MLC area has low cost, the proposed scheme utilizes the SLC area as log buffer and the MLC area as data block. Considering the high write cost of MLC flash, the garbage collection for the SLC log buffer moves a page into the MLC data block only when the page is cold or the page migration invokes a small cost. The other pages are moved within the SLC log buffer. Also it adjusts the parameter values which determine the operation of garbage collection adaptively considering I/O pattern. From the experiments, we can know that the proposed scheme provides better performance compared with the previous flash management schemes for the hybrid flash and finds the parameter values of garbage collection close to the optimal values.

• The Journal of Korean Institute of Information Technology
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• v.17 no.11
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• pp.17-26
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• 2019

RAID-5 technology is one of the choice for flash storage device to enhance its reliability. However, RAID-5 has inherent parity update overhead, especially, parity overhead for partial stripe write is one of the crucial issues for flash-based RAID-5 technologies. In this paper, we design efficient parity log architecture for RAID-5 to eliminate runtime partial parity overhead. During runtime, partial parity is retained in buffer memory until full stripe write completed, and the parity is written with full strip write. In addition, parity log is maintained in memory until whole the stripe group is used for data write. With this parity log, partial parity can be recovered from the power loss. In the experiments, the parity log method can eliminate partial parity writes overhead with a little parity log writes. Hence it can reduce write amplification at the same reliability.