• Asia-pacific Journal of Multimedia Services Convergent with Art, Humanities, and Sociology
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• v.9 no.9
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• pp.819-831
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• 2019

The types of properties traded in modern times are rapidly increasing due to changes in consumption patterns. However, as the type of properties traded increases, estimation about the value of properties may become inaccurate. There is a problem that it is difficult for consumers to estimate the right value and the variety of trading forms makes it difficult to guarantee the reliability of value estimation As access to a variety of properties has expanded, these shortcomings are considered to be a factor that hinders the stability of the shared economic market. In this paper, to resolve this issue, we present a blockchain-based property contract service through a trusted broker. The developed service registers trusted brokers into smart contracts on the Ethereum blockchain and use them for the evaluation and contract process of properties. In addition, registered contents, proposals and contracts of properties are stored in the blockchain to ensure the reliability of the contract process. Every step of the contract process is stored in the smart contract, recorded in the transaction history of the blockchain, ensuring the reliability of the stored data. In addition, the entire process of registration, proposal, and contract is driven by smart contracts designed by state machine technology, enabling users to more securely control the contract process.

• The Journal of the Convergence on Culture Technology
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• v.9 no.3
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• pp.633-640
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• 2023

In this study, numerical analysis was performed based on field investigation to derive an appropriate reinforcement method by analyzing the displacement behavior characteristics of concrete blocks generated in the direct fixation track on the bridges of the serviced light rail transit. The track of this study was a direct fixation track on a sharp curved track, and the problem of movement of the concrete blocks installed on the bridge deck in the longitudinal and lateral directions occurred. In this study, based on the finite element model using 3D solid elements, the behavior of the direct fixation track that could be occurred under operating load conditions was analyzed. In addition, the reinforcement effect of various reinforcement methods was analyzed. As a result of analyzing the lateral displacement before and after reinforcement, it was analyzed that the maximum lateral displacement after reinforcement under the extreme lateral wheel loads significantly decreased to about 3% (about 0.1mm) compared to before reinforcement. In addition, as a result of examining the generated stress of the filling mortar, bridge decks, and reinforcing bar, it was analyzed that all of them secured a sufficient safety factor of 2.6 or higher, and the optimal conditions for the reinforcement method were derived. Therefore, it is judged that the number of anchoring reinforcements and symmetrical anchor placement reviewed in this study will be effective in controlling the occurrence of lateral displacement of concrete blocks and securing the structural integrity of bridges and concrete blocks.

• Proceedings of the Korean Information Science Society Conference
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• 2004.10b
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• pp.523-525
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• 2004

컴포넌트 지향 개발 방법이 도입되면서 많은 분산환경하에 컴포넌트들이 상호 연동하여 사용되어지기 시작했다. 그러나 분산환경에서의 상호연동은 많은 어려움과 과제를 우리에게 안겨주었다. 이를 보안하여 상호운영성을 고려한 웹 서비스의 개념이 나오기 시작하고 있다. 웹 서비스는 이기종간의 컴포넌트 서비스를 쉽게 구현할 수 있게 하며 컴포넌트들을 이용에 블록을 쌓듯이 애플리케이션을 만들 수 있다. 그러나 웹 서비스는 아직 QoS 문제가 남아있다. 웹 서비스의 품질을 보장하고 사용자가 웹 서비스를 안전하게 사용하기 위해서는 QoS 기반 컴포넌트 조립이 필수적이다. 본 논문은 로컬 브로커와 XML-QoS 스키마를 사용하여 사용자가 QoS를 고려한 실행 계획을 세울 수 있게 한다.

• Review of KIISC
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• v.6 no.1
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• pp.65-78
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• 1996

본 논문에서는 JPEG 알고리즘을 이용하여 화상데이터를 부호화할때 디지털 서명문과 같은 기밀 데이터를 몰래 집어넣어 합성하는 방식에 대하여 고찰한다 그 기본원리는 DCT 계수를 양자화 할 때 필연적으로 생기는 오차를 이용하는 것으로 0이 아닌 양자화 계수를 합성하고자 하는 기밀데이터에 따라 근처의 정수로 조절하는 것이다. 이 방식을 SIDBA 표준화상에 적용하여 화상의 열화는 무시할 정도로 작으면서 원하는 크기의 기밀 데이터를 합성할 수 있음을 보인다. 또한, 화질의 열화를 최소화시키면서 일정량의 기밀 데이터를 합성시키기 위하여 블록당 1화소를 적절히 선택하여 제3자의 공격에 대한 안전성을 향상시키는 방법을 제시하고 컴퓨터 시뮬레이션을 통하여 성능을 분석한다.

• Proceedings of the Korea Institutes of Information Security and Cryptology Conference
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• 2003.12a
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• pp.190-194
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• 2003

이 논문에서는 블록 암호 알고리즘인 XTEA에 관한 연관키를 이용한 차분공격에 대하여 설명한다. 이것은 XTEA 알고리즘이 TEA가 갖고 있는 취약한 키 스케줄을 보완하여 Kelsey 등이 제안한 연관키 공격에 대응하기 위하여 설계되었지만, 26 라운드로 줄인 XTEA 또한 우리의 연관키를 이용한 차분공격에 안전하지 못하다는 것을 보여준다. 또한 키 스케줄에 의하여 다양하게 변화된 라운드의 XTEA에 관한 연관키 공격이 가능하다. 이 때 필요한 선택평문과 암호화 과정은 각각 2$^{18.5}$ 과 2$^{115.21}$ 이다.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.10 no.1
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• pp.13-22
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• 2000

본 논문에서는 Skipjack의 변환규칙 A와 같은 반복적인 구조에 대한 차분 특성 및 선형 근사식의 확률의 상한 값을 제시하고 이를 증명한다. 즉 라운드 함수에 대한 확률의 최대 값이 p이면 15라운드 후에 p4이 됨을 보인다. 따라서 본 논문에서 고려한 구조는 현재까지 DC 및 LC에 대한 안전성을 증명할 수 있는 구조인 Feistel 구조 및 MISTY 구조와 더불어 블록 암호의 설계 방법에 대한 다양성을 제공한다.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.14 no.2
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• pp.343-350
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• 2010

In the existing design of web server architecture, data encryption technique is used to keep the reliability, stability, and safety of web service. But the use of data encryption technique wastes the work of cpu while decreasing throughput of web server and increasing average response time so that it shows negative effect on the capacity of web application server. Also, the latest web applications require security and safety for the safe internet communication. Therefore, this paper suggests the improved web server which uses thread pool and Non-blocking I/O adding new web service modules to the existing web server for the safe web service, provides reliability and safety to show the safe web service capacity. And we compare and evaluate the safety and capacity through experiment on the existing traditional Tomcat based web server and the proposed system to evaluate the safety and capacity of the proposed web server system.

• Tunnel and Underground Space
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• v.11 no.3
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• pp.279-288
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• 2001

Jointed rock mass can be analyzed by either continuum model or discontinuum model. Finite element method or finite difference method is mainly used for continuum modelling. Although discontinuum model is very attractive in analyzing the behavior of each block in jointed blocky rock masses, it has shortcomings such that it is difficult to investigate each joint exactly with the present technology and the amount of calculation in computer becomes trio excessive. Moreover, in case of the jointed blocky rock mass which has more than 2 dominant joint sets, it is impossible to model the behavior of each block. Therefore, a model such as ubiquitous joint model theory which assumes the rock mass as a continuum, is required. In the case of tunnels, unlike slopes, it is not easy to obtain safety factor by utilizing analysis method based on limit equilibrium method because it is difficult to assume the shape of failure surface in advance. For this reason, numerical analyses for tunnels have been limited to analyzing stability rather than in calculating the safety factor. In this study, the behavior of a tunnel excavated in jointed rock mass is analyzed numerically by using ubiquitous joint model which can incorporate 2 joint sets and a method to calculate safety factor of the tunnel numerically is presented. To this end, stress reduction technique is adopted.

• Journal of the Korea Safety Management & Science
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• v.9 no.3
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• pp.165-171
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• 2007

Dependent models in quality statistics are classified as serially autocorrelated model, multivariate model and dependent sample model. Dependent sample model is most efficient in time and cost to obtain samples among the above models. This paper proposes to implement parametric and nonparametric models into production system depended on demand pattern. Nonparametric models have distribution free and asymptotic distribution free techniques. Quality statistical models are classified into two categories ; the number of dependent sample and the type of data. The type of data consists of nominal, ordinal, interval and ratio data. The number of dependent sample divides into 2 samples and more than 3 samples.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2007.12a
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• pp.170-172
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• 2007

미포만 공유수면 매립공사는 방파호안 854.5m를 축조하고 부지 $100,514.3m^{2}$를 매립하여 현대중공업(주)의 조선용 블록 제작장 및 적치장을 조성하는 사업이다. 2004년 2월 해양 수산부 설계자문을 실시하고, 2004년 5월 실시계획 인가를 득하여 사업을 추진하여 오던 중, 최근의 이상파랑 및 태풍 내습 (2005년 8월, 태풍 나비)등으로 인하여 피해가 발행하는 동 사업시행자인 현대중공업(주)에서 사업계획의 일부 변경(공구분할)올 요청하여 1공구(미포만 북방파제 보강)공사만을 2005년 8월말로 완료하였다. 미포만 공유수면(II-Block) 매립공사(2공사)는 파량 내습시 피해발생 사전예방 및 상향된 심해설계파 등에 안전한 구조물 축조로 배후매립부지의 안전성을 확보할 수 있도록 호안의 마루높이를 상향하고 케이슨 및 피복재 중량을 증대하여 설계 및 시공할 수 있도록 하였다.