• Journal of KIISE:Computer Systems and Theory
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• v.34 no.12
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• pp.683-695
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• 2007

NAND flash memory-based file systems cannot store their system-related information in the file system due to wear-leveling of NAND flash memory. This forces NAND flash memory-based file systems to scan the whole flash memory during their mounts. The mount time usually increases linearly according to the size of and the usage pattern of the flash memory. NAND flash memory has been widely used as the storage medium of mobile devices. Due to the fact that mobile devices have unstable power supply, the file system for NAND flash memory requires stable recovery mechanism from power failure. In this paper, we present design and implementation of a new NAND flash memory-based file system that provides fast mount and enhanced stability. Our file system mounts 19 times faster than JFFS2's and 2 times faster than YAFFS's. The stability of our file system is also shown to be equivalent to that of JFFS2.

• The Korean Journal of Applied Statistics
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• v.29 no.6
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• pp.1077-1094
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• 2016

Apache Spark is a fast and general-purpose cluster computing package. It provides a new abstraction named resilient distributed dataset, which is capable of support for fault tolerance while keeping data in memory. This type of abstraction results in a significant speedup compared to legacy large-scale data framework, MapReduce. In particular, Spark framework is suitable for iterative machine learning applications such as logistic regression and K-means clustering, and interactive data querying. Spark also supports high level libraries for various applications such as machine learning, streaming data processing, database querying and graph data mining thanks to its versatility. In this work, we introduce the concept and programming model of Spark as well as show some implementations of simple statistical computing applications. We also review the machine learning package MLlib, and the R language interface SparkR.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.2
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• pp.378-385
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• 2016

The internal circuit of the bus-bar for an electrical switch board is a prime cause of electric shock and short circuit accidents due to the exposure of live parts. Electrical fires can also be caused by animals and foreign substances in the switchboard that connect the components with a difficult structure resulting in overheating due to an increase in contact resistance. Preventing these types of accidents is a prime concern in the manufacturing process, such as cutting and bending. In this study, the cutting bus bar of a switch board contained improved modules as a flame retardant that isolates a separate blocks to prevent such problems. This was implemented as a scalable and flexible means of reducing electrical switchboard hazards to offer a safe switch board bus-bar structure of a new connecter type

• Journal of the Society of Disaster Information
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• v.9 no.4
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• pp.521-531
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• 2013

Temporary residence in disaster scenarios emergency response system designed for utilizing emergency incident types identified through the rapid emergency response procedures and proper application of the resulting accident is very important in order to minimize the damage. In this study, emergency disaster expected to analyze the potential for accidents, the possible accident scenarios emergency disaster preparedness These were derived on the basis of temporary residence in the emergency scenario, the scenario for the emergency response and recovery measures were derived. In addition, each event of an emergency response scenario to be taken during the emergency response requirements for emergency response to a step-by-step behavior was defined by the subject. In addition, subject-specific, step-by-step emergency disaster scenarios emergency response is quick and can be done in a comprehensive foundation was laid.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.28 no.8A
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• pp.569-580
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• 2003

One of the important advantages of multichannel switches is the incorporation of inherent fault tolerance into the switching fabric. For example, if a link which belongs to the multichannel group fails, the remaining links can assume responsibility for some of the traffic on the failed link. On the other hand, if faults occur in the switching elements, it can lead to erroneous routing and sequencing in the multichannel switch. We investigate several fault localization algorithms in multichannel crossbar ATM switches with a view to early fault recovery, The optimal algorithm gives the best performance in terms of time to localization but is computationally complex which makes it difficult to implement. We develop an on-line algorithm which is computationally mote efficient than the optimal algorithm. We evaluate its performance through simulation. The simulation results show that performance of the on line algorithm is only slightly sub-optimal for both random and bursty traffic. Finally a fault recovery algorithm is described which utilizes the information provided by the fault localization algorithm.

• Proceedings of the Korea Water Resources Association Conference
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• 2015.05a
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• pp.581-581
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• 2015

기후변화의 영향으로 자연재해 현상이 더욱 심각해지고 있다. 기상청에 의하면 서울특별시의 2005~2014년의 강수량은 1970년대에 비해 여름철에 38.7% 증가한 반면, 나머지 계절은 8.7%감소하여 홍수와 가뭄의 빈도가 상승하는 역설적 현상이 나타나고 있다. 또한 수도권 지역의 경우 도시화로 인한 불투수 면적 증가로 하천변의 홍수 피해지역이 더욱 증가되고 있는 실정이다. 재해 발생 규모는 점차 대형화되고 유형 또한 다양화되어 재해 발생 시 단순히 단일 지역이 아닌 여러지역에 걸쳐 피해가 발생되고 있다. 때문에 협력과 연계를 통한 치수대책이 효과적이지만, 현재 재해관련 업무는 여러 부처에 분산되어 있으며 지자체간 협력이 미흡한 실정이다. 이러한 한계를 극복하기 위해 본 연구에서는 재해 발생 시 피해를 최소화하기 위해 지자체들의 개별화 되어있는 대책을 서로 연계하는 방재협력시스템과 방재 대책 협력 방안을 제시하고자 한다. 국내 외 방재정책의 패러다임을 진단하기 위하여 관련 법령과 자료 및 도시의 협력대응사례를 조사, 분석하여 새로운 패러다임을 수립하고 이를 기초로, 기후변화를 고려하여 새로운 방재시스템을 제시하고 재난관리 협력방안을 모색하였다. 본 연구를 통하여 제안하고자 하는 새로운 방재시스템은 복구와 구조물적 대응 위주인 기존의 방재 패러다임에서 예방에 의한 방재와 탄력적 대응을 도입하도록 하여 예방적 차원의 이슈를 논의하고 비구조물/구조물 융합형 방재 개념을 실제 시스템으로 사용하도록 구체적 방안을 제안하였다. 또한 기존의 국내 도시방재형 패러다임을 분석한 결과, 인접지역의 계획간 연계가 부족하여 정책적 사각이 발생하고, 재해취약지역이 적절히 관리되지 못할 위험성이 존재하며 환경이나 지속 가능성에 취약한 형태가 될 수 있다. 따라서 수도권 내 지방자치 단체 간 협력을 통하여 사용할탄력적 개념을 제시하였으며, 이 개념의 적용을 통하여 효율적 재해 대응이 이루어 질 수 있다. 본 연구의 정책 제안을 기반으로 수도권 내 서울시 인천시 경기도 지역이 상호 협력하여 탄력적인 방재시스템을 구축하기 위한 기초자료로 활용될 수 있을 것으로 사료된다.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.24 no.11
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• pp.1507-1518
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• 2020

High-quality images have a lot of information, so sensitive data is stored by encryption for private company, military etc. Encrypted images can only be decrypted with a secret key, but the original data cannot be retained when attacked by the Shear attack and Noise pollution attack techniques that overwrite some pixel data with arbitrary values. Important data is the more necessary a countermeasure for the recovery method against attack. In this paper, we propose a random number generator PingPong256 and a shuffling method that rearranges pixels to resist Shear attack and Noise pollution attack techniques so that image and video encryption can be performed more quickly. Next, the proposed PingPong256 was examined with SP800-22, tested for immunity to various noises, and verified whether the image to which the shuffling method was applied satisfies the Anti-shear attack and the Anti-noise pollution attack.

• Proceedings of the Korea Water Resources Association Conference
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• 2021.06a
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• pp.486-486
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• 2021

국가에서는 수해예방 및 주민들의 삶의 질 향상을 위해 다양한 하천사업을 수행한다. 국토교통부의 경우 매년 막대한 예산을 투입하여 하천정비 및 재해복구사업 등을 추진 중에 있으나, 체계적인 공사관리와 산출물의 전산화를 위한 시스템은 부재한 실정이다. 현재 건설사업정보시스템(건설CALS)을 통해 하천공사에 관한 정보를 확인할 수 있으나 총 공사비, 참여업체 등 기본적인 정보만을 제공하고 있으며, 공정관리 및 예산정보에 관한 상세한 내역을 확인 및 관리할 수 있는 기능은 부재하다. 이러한 문제를 해결하고자 본 연구에서는 하천사업(공사)관리시스템의 필요성을 제시함과 동시에 우선적으로 하천사업 공종 표준화를 수행하고자 한다. 현재 건설공사표준품셈을 통해 건설공사의 공종을 확인할 수 있으나 '제2장 하천공사' 내에는 사석, 돌망태, 하천호안공에 관한 정보만을 담고 있다. 하천공사 공종 표준화를 진행하게 될 경우 공종별 공사 세부정보에 대한 관리가 가능해지며, 현재 하천을 관리 중인 국토교통부, 지방국토관리청 및 지자체 등 하천사업을 수행 중인 기관의 시스템 활용도를 제고할 수 있다. 하천사업 공종표준화를 위해 우선적으로 현재 건설공사표준품셈, 도로대장 전산화 입력지침 등기 수립된 지침 및 기준을 통해 건설토목공사 시의 공종을 조사·분석한 후, 하천공사 준공보고서 및 감리보고서 등 공사 관련 자료를 활용하여 하천공사에 주로 수행되는 공사들에 관한 종류를 도출하였다. 이후 건설토목공사 공종과의 비교·분석을 통해 하천공사에서 주로 수행되는 공종을 도출·표준화하는 작업을 진행하였다. 본 연구에서 제시한 하천사업 공종의 경우 향후 하천사업(공사)관리시스템 개발에 활용이 가능하며, 하천공사 관리의 효율성을 극대화할 수 있다.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.30 no.4D
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• pp.331-338
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• 2010

In the case of Korea, research on traffic management is insufficient to cover the increasing incidence of disaster. Furthermore, many of the traffic management manual does not touch up on how to administer/manage in case of disaster, except for the one made by 'Korea Expressway Corporation.' In response to this issue, this research is based on a thesis to establish concept of guideline for traffic management in the case of an disaster. In order to achieve this goal, there has been an analysis of the American's manual, molded and changed to be Korea-specific. In the future, based on the u-T circumstances are established, traffic management will become much more efficient. This paper presents important details and ways of management for each step of an disaster event: prevention, preparation, response and restoration.

• Journal of Yeungnam Medical Science
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• v.20 no.2
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• pp.105-116
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• 2003

Definitely, treatment for gastric cancer is primarily surgical. Detection in early stage of disease and complete surgical resection is the best way to cure gastric cancer. If surgery is planned, careful preoperative evaluation and corrections of physiologic and psychologic abnormalities are essential to reduce perioperative morbidity or mortality. Basic principle of gastrectomy for gastric cancer is an en bloc resection of tumor with adequate margins of normal tissue and with regional lymph nodes and omental tissues. To complete these principles, regional lymph nodes and all omental tissues should be removed altogether during performing various types of gastric resection. The lymph node dissection is one of the most effective procedures for gastric cancer to achieve curative resection. The basic types of gastric resection are distal subtotal gastrectomy and total gastrectomy according to the condition of primary lesions and the status of lymph node metastases. When the primary lesion is located near the esophagogastric junction, it is sometimes hard for a surgeon to select adequate surgical method. Postoperative quality of life in a patient has become a very important factor to be considered in every step of surgical therapy. With increasing incidence of early gastric cancer, a number of surgical trials for limited surgery or endoscopic procedures have been performed, but the long-term clinical results should be carefully analyzed to define the clinical relevance of these new techniques. For patients with disseminated gastric cancer, a palliative procedure can be performed to improve quality of life of patients and to avoid immediate death due to the cancer-related complications.