• Journal of the Korea Society of Computer and Information
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• v.13 no.4
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• pp.105-113
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• 2008

While the wireless sensor network has a strong point which does not have effect on whole activities of network even though neighboring sensor nods fail activities of some sensor nod or make some functions disappear by the characteristic of similar information detection, it has problems which is slowing down of wireless medium, transfer character with severe error, limited power supply, the impossibility of change by optional arrangement of sensor nods etc. This paper proposes PRML techniques which performs the fittest course searching process to reduce power consumption of entire nods while guarantees the scalability of network organizing sensor nods hierarchically. The proposed technique can scatter the load of cluster head by considering the connectivity with surplus energy of nod and reduce the frequency of communication among the nods. As a result of the analysis in comparison with LEACH-C and HEED technique, PRML technique get efficiency of average 6.4% in energy consuming respect of cluster head, efficiency of average 8% in entire energy consuming respect, and more efficiency of average 7.5% in other energy consuming distribution of network scalability than LEACH-C and HEED technique.

• Journal of KIISE:Computer Systems and Theory
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• v.30 no.7_8
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• pp.352-358
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• 2003

A cluster of servers is the most promising solution to provide highly scalable and highly available network services with low implementation cost. One of popular solutions is using dispatcher as a request distributor. However this solution has the problem that is can be the bottleneck or single-point of failure point of itself. ONE-IP, the previous work, solves this serious problem by using broadcast message for distributing the request packet in LAN. Using simple scheduling technique, in addition, the overhead due to dispatching the request becomes minimal. However, as ONE-IP using very simple static scheduling algorithm, it would spread the request among servers unevenly and downgrades the cluster performance consequently. In this paper, we propose an improved TCP connection scheduling technique solving this unbalanced distributing problem. Using Round-Robin(RR) scheduling instead of hashing clients IP address, proposed technique can more evenly distribute incoming service requests among the servers. Experiments show average 3.8% improved performance in throughput compared to original ONE-IP technique.

• Tunnel and Underground Space
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• v.18 no.2
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• pp.107-117
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• 2008

In this study, the failure and deformation characteristics of steel fiber reinforced shotcrete (SFRS) which is a primary tunnel support was investigated to find out ground-support mutual behavior. To this end, a mock-up of a tunnel was made and experimented with the conditions of lateral earth pressure coefficient 0.5 and 1.0. During the tests, 11 hydraulic cylinders were used for loading. for better simulation of the lateral earth pressure effect, these cylinders were controlled separately by two groups; crown and side wall. Meanwhile, the deformation of shotcrete was measured by 11 LVDTs. Backfill material was also used fur better load transfer from hydraulic cylinders to shotcrete. For the validation of the mock-up test results, 3D numerical analysis is carried out. To do numerical analysis under the same condition as a mock-up test, the load history curve which was obtained during the test was tried to be simulated using an individual FISH routine in the numerical analysis.

• Journal of Convergence for Information Technology
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• v.9 no.11
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• pp.15-21
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• 2019

Allowing only authorized users to record and inquire in the ledger, private blockchain technology is attracting attention from institutions and companies. Based on distributed ledger technology, records are immutable. Because news via the Internet can be easily modified, the possibility of manipulation is high. Some false communication report systems are designed to prevent such harm. However, during the gap between the false communication report and verification time, contents on the website can be modified, or false evidence can be submitted intentionally. We propose a system that collects evidence using a headless browser for more accurate false communication management, and securely preserves evidence through a private blockchain and prevents possibilities of manipulation. The proposed system downloads original HTML, captures the website as an image, stores it in a transaction along with the report, and stores it in a private blockchain to ensure the integrity from acquisition to preservation of evidence.

• Journal of Korea Society of Industrial Information Systems
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• v.14 no.2
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• pp.8-15
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• 2009

The need for ASP(Application Service Provider) has evolved from the increasing costs of specialized software that have far exceeded the price rage of small to medium sized businesses. There are a lot of technologies that make ASP possible, and software streaming service is one of them Software streaming is a method for overlapping transmission and execution of stream-enabled software. The stream-enabled software is able to run on a device even while the transmission/streaming of the software may still be in progress. Thus, a user does not have to wait for the completion of the software's download prior to starting to execute the software. In this paper, we suggest the new concept of software streaming system implement using the PageFault Interrupt Routine Hooking. As it is able to efficiently manage application, we do not have to install the entire software. In addition, we can save hardware resources by using it because we load basic binaries without occupying the storage space of the hardware.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2022.05a
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• pp.158-160
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• 2022

Many office workers spend a lot of time performing repetitive office tasks in inefficient ways. We developed a user-friendly chatbot system based on Kakaotalk to automate repetitive tasks and used the chatbot in the real workplace. In the process of operating the chatbot, if several people use the chatbot at the same time, the server was down or could not respond. To address these issues, we performed code migration of programs used by chatbot back-end servers and tried several ways to improve server performance such as database redesign and load balancing. To determine how much each method affects performance improvement, we measured total request per second and average latency. After that, we proposed ways to improve the problems of using the chatbot in the work environment.

• Proceedings of the Korea Water Resources Association Conference
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• 2020.06a
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• pp.76-76
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• 2020

국가 물관리일원화 이후, 지방하천 관리에 대한 지자체 역할과 권한이 커지고 있으며, 중앙정부의 물관리 수준에 부합하는 데이터관리 체계구축 및 지속적인 품질관리(Quality Control, QC)와 표준화(Standardization) 기술개발이 요구되고 있다. 지자체의 경우 기존의 행정구역별로 분산 관리해오던 물관리 시스템을 유역단위로 전환할 필요가 있으며, 국가하천 구간과 연계한 종합적인 관리가 필요한 실정이다. 서울시의 물관리 시스템은 자치구별로 산재해 있으며, 관리 주체 및 해당 변수에 따라 제공되는 정보가 다르고 하천유역 단위로 분류되어 있지 않다. 따라서, 서울시와 자치구, 중앙정부 및 관련 기관과의 연계성 있는 정보제공을 위한 데이터 플랫폼 구축 기술개발이 필요한 실정이다. 본 연구에서는, 빅데이터, AI 기술을 활용한 물정보의 품질관리 자동화 기술개발과 지속적인 유지관리 및 표준화 정보제공 시스템 구축 기능을 포함하는 서울시 통합물관리 데이터 플랫폼 구축 목표 모델을 제시하였으며, 서울시 물관리 체계와 관련하여 SWAT 분석을 통한 단계별 사업추진 로드맵을 도출하였다. 분석결과, 서울시 통합물관리 플랫폼 구축을 위해서는 유역별 수량-수질 통합 모니터링 및 모델링 기술개발, 빅데이터 기반 물 정보화 플랫폼 구축 기술개발, 지방하천 유역 거버넌스 구축 및 법제도 정비 방안 마련이 요구되며, 관련하여 주요 이슈(3대 핵심전략, 10개 단위과제)를 도출하여 관련 연구과제를 제안하였다. 마지막으로, 서울시 통합물관리 정책 실현을 위해서는 법제도 마련이 시급하며, 서울시 '통합물관리 기본조례' 제정을 통한 기반을 조성할 필요가 있음을 시사하였다. 또한, 다양한 분야 이해관계자 협의체인 '서울시 통합물관리위원회(가칭)'의 거버넌스를 구성하여 운영하는 것이 현실적이며, 한강유역관리 및 지방하천 관리와 관련한 중추적인 역할 수행과 쟁점 논의 등 합리적 합의가 가능할 것으로 기대한다.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2022.10a
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• pp.577-579
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• 2022

It is not easy to achieve the essential goal of knowledge management, which is to strengthen individual competence and organizational competitiveness, only by collecting distributed knowledge in the centralized knowledge repository conducted so far. In order to establish a sustainable knowledge ecosystem, we must expand knowledge production through exchange and cooperation, not independent knowledge production. Through this, producing meaningful and high-value knowledge resources becomes possible. Therefore, this study aims to design an integrated service platform that stores science and technology knowledge resources and reproduces and evolves knowledge through opening, sharing, and utilization. In order to evaluate its excellence, Five experts evaluated the designed platform on detailed items classified into planning adequacy, platform effectiveness, platform efficiency, and roadmap adequacy. The evaluation score averaged 95.56 points for the above four evaluation items.

• International Area Studies Review
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• v.15 no.1
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• pp.107-133
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• 2011

This paper aims to analyze the causal relationships between agricultural exports and economic growth in the U.S. economy by 50 states. Using the annual data from 1973 to 2007, the theoretical methodologies based on the export-led growth (ELG) model under the static model, the impulse response function (IRF) and forecast error variation decomposition (FEVD) under the vector autoregressive (VAR) model, and the Granger causality test. The results show the causal relationship between agricultural exports and economic growth at the states' level. Especially, the ELG hypothesis is strongly supported in the case of 16 states (HI, ID, KS, MD, MI, MN, NJ, NC, ND, OK, OR, RI, SD, TX, WA, and WI) and is also weakly supported in the case of 31 states. Therefore, the agricultural exports are important factor of developing in the U.S. economy, and furthermore some states (located in coastal area and breadbasket) indicate the strong evidence for agricultural exports-led growth.

• Proceedings of the Korea Information Processing Society Conference
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• 2007.11a
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• pp.1270-1273
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• 2007

최근 인터넷의 급속한 발달은 온라인 뱅킹, 인터넷 쇼핑몰 등에서의 실물 경제행위를 온라인상으로 처리할 수 있는 환경을 제공하지만 온라인상의 업무처리는 개인정보유출, 개인정보의 위조 및 변조 등의 문제를 가지고 있다. 사용자가 CA에게서 받은 인증서의 공개키로 전자서명 함으로써 개인정보유출, 정보의 위조 및 변조 등의 문제를 해결한 PKI(Public Key Infrastructure)기반의 인증서 검증시스템이 제안되어 사용되고 있다. 인증서 상태검증 방법에는 CRL(Certificate Revocation List)기반의 검증방식, OCSP(Online Certificate Status Protocol)기반의 검증방식 등이 있다. CRL기반의 인증서 검증방식은 인증서 취소목록을 검색해서 인증서의 유효성 여부를 응답하는 방식으로 시간이 지남에 따라 크기 증가와 오프라인 방식으로 인해서 목록을 다운받는 시간의 부담으로 인해서 OCSP방식이 제안되었다. 하지만 OCSP 방식 역시 서비스의 요청이 집중될 경우 문제가 발생될 수 있다. 그래서 분산된 OCSP를 구축하고 각 서버의 부하의 균형을 유지하기 위해 로드밸런싱 기법을 사용하고 있지만 그 방법 역시 지속적인 서비스 제공이 불가한 문제를 가지고 있다. 본 논문에서는 서비스 요청의 집중으로 인한 시스템 마비나 각 응답서버의 부하가 불균형적임으로써 생길 수 있는 문제를 해결할 수 있는 방법을 제안한다.