• KIPS Transactions on Computer and Communication Systems
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• v.11 no.6
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• pp.175-184
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• 2022

Blockchain is being studied in various fields such as logistics, fintech, medical care, and the public sector. In the public information software project, some deliverables are omitted because the developed deliverables and the deliverables requested by the project management methodology do not match, and an additional process is required for payment. In this paper, we propose the deliverables management system for public information software project which is configured a distributed environment using the Ethereum blockchain and which has an automatic payment system only when all deliverables are approved. This system can keep the service available in case of system failure, provide transparency and traceability of deliverables management, and can reduce conflicts between the ordering company and the contractor through automatic payment. In this system, the information of deliverables is stored in the blockchain, and the deliverables that their file name is the hash value calculated by using the version information and the hash value of the previous version deliverable, are stored in the SFTP server. Experimental results show that the hash value of the deliverables registered by the contractor is correct, the file name of the deliverables stored in the SFTP server is the same as the hash value registered in the Ethereum blockchain, and the payment is made automatically to the Ethereum address of the contractor when all deliverables are approved.

• Proceedings of the Korean Information Science Society Conference
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• 2006.06d
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• pp.316-318
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• 2006

본 논문에서는 차세대 지능형 교통시스템인 UTIS(Urban Traffic Information System)의 빠른 접속 요구 조건을 만족하기 위한 DLC(Dynamic Limited Contention) 알고리즘을 제안한다. UTIS 네트워크는 고속으로 이동하는 차량에 설치된 모바일 노드와 도로 변에 설치된 노변 기지국으로 구성되며, 이 네트워크를 통해서 IP 데이터 그램의 전송 서비스, 방송 데이터를 실시간으로 전송하는 실시간 전송 서비스 그리고 차량의 위치를 계속적으로 알려 주는 위치 탐색 서비스를 지원한다. 이러한 전송 서비스를 지원하기 위해서 UTIS는 물리 계층과 MAC 계층으로 구성된다. 그러나 UTIS에서는 차량의 고속 이동으로 인해서 셀(cell)간의 핸드오프가 빈번히 발생하고 또한 위치 추적과 방송 서비스와 같은 실시간 전송 서비스를 지원해야 하기 때문에 기존의 802.11 MAC을 사용할 수 없다. 즉 UTIS에서의 빠른 등록 요구 조건을 충족시키기 위해 기존의 802.11에서 사용하는 경쟁(contention) 방식은 비효율적이다. 본 논문에서는 셀 내에 도착하는 노드 수에 따라 경쟁을 하는 그룹의 크기를 동적으로 조절하는 DLC 알고리즘을 제안한다. 기존의 UTIS에서는 그룹 크기를 정적으로 결정하고 모바일 노드는 자신의 주소에 이 정적 그룹 크기로 modulo하여 자신의 속한 그룹을 초기에 계산한다. 기지국이 접속해야하는 그룹을 폴링 메시지로 지정할 때 그 그룹에 속한 모바일 노드들만이 제한적으로 경쟁하게 된다. 이러한 정적인 그룹 크기는 셀 내에의 노드의 숫자와 그룹 크기의 분포를 고려하지 않는 방식으로 비효율적이다. 본 DLC 알고리즘에서는 전 폴링 주기 동안에 경쟁하는 노드의 빈도수를 계속적으로 추적하여 등록 시점에 경쟁하는 그룹의 개수를 동적으로 조절하게 된다. 이러한 방식은 UTIS와 같이 접속 시간이 제한적이고 접속하려는 노드 수가 빠르게 변화하는 환경 하에서 기존의 802.11 MAC 프로토콜과 정적인 그룹 크기 방식에 비해 효율적이다.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.18 no.5
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• pp.1122-1127
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• 2014

WLAN is affordability, flexibility, and ease of installation, use the smart device due to the dissemination and the AP (Access Point) to the simplification of the Office building, store, at school. Wi-Fi radio waves because it uses the medium of air transport to reach areas where security threats are always exposed to illegal AP installation, policy violations AP, packet monitoring, AP illegal access, external and service access, wireless network sharing, MAC address, such as a new security threat to steal. In this paper, signature-based of wireless intrusion detection system for Snort to suggest how to develop. The public can use hacking tools and conduct a mock hacking, Snort detects an attack of hacking tools to verify from experimental verification of the suitability of the thesis throughout.

• Journal of The Korean Association of Information Education
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• v.16 no.4
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• pp.397-407
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• 2012

According to the fast supply of the SMART device, many people have a lot of interests about SMART education. The Korean government is showing a lot of effort towards the promotion of SMART education. In this study, I developed a behavioral assessments and QR code based mobile web application for school education. The developed system works seamlessly across all popular mobile device platforms and if you save the data after the assessment, this system will automatically create each person's mobile web page. Students and teachers can add comments to this page and can improve the accessibility for finding the address of this page to QR code. The developed system can contribute to the class members understanding the personality of each other and make communication run smoothly. As a result of application of developed system, it is expected to contribute to increasing the interaction between a students, parents and teachers because the developed system provides a service based to education consumer's TPO(Time, Place, Occasion).

• The Journal of Korean Institute of Communications and Information Sciences
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• v.40 no.12
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• pp.2401-2409
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• 2015

This paper proposes the improved handoff mechanism for IEEE 802.11 wireless LANs. When a wireless mobile node moves out of the coverage of its currently associated AP(Access Point) and needs to be re-associated with a new AP, a handoff procedure is initiated. Channel scanning process during a handoff procedure occupies over 90% of total handoff latency. Long latency leads to many packet losses and service discontinuity, which degrades wireless network performance. This paper describes about the new mechanism to improve handoff performance by skipping channel scanning during a handoff procedure. In oerder for that, acquires neighboring AP information such as its address, location, channel number in use, the number of associated nodes before handoff, and delivers the information to its associated mobile nodes. The mobile nodes can reduce handoff latency and perform more exact handoff using the delivered AP information. We have conducted simulations to analyze our proposal's performance and confirmed that handoff latency and the number of handoff occurrences are decreased.

• International Commerce and Information Review
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• v.19 no.3
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• pp.129-150
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• 2017

The Hallyu, or Korean Wave, has recently been proliferating around the world focusing on Asia. With the development of China's economy and the improvement of their people's living standards, Chinese consumption has been growing quickly. In cosmetic industry, Chinese consumers tend to prefer international brands including Korean cosmetics. There are various ways for Chinese consumers to purchase international brand cosmetics. One of them is overseas purchase via buying agent. This study is designed to exam various determinants of the overseas purchase. Based on empirical findings, product price and functionality can play an important role in terms of the overseas purchase. Also, moderating effects of an external factor(importing country's favorability) was empirically investigated. The results of SEM(Structural Equation Modeling) show that the relationship between consumer openness and overseas purchase via buying agent can be positively moderated by the favorability.

• The KIPS Transactions:PartC
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• v.13C no.5 s.108
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• pp.583-594
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• 2006

The reliability concept of wireless sensor network is essential to get exactly actual data from the ubiquitous environment. A rollback technique for the self-healing helps to increase it. However, a fault can occur in wireless sensor network when to use a previous rollback technique because it is designed just for the local system. So, checkpoint protocols are suggested in order to use a rollback technique in the network without the fault. However, there is trade-off among performance overhead, power consumption, and memory overhead for each of protocols. Hence, we suggest a novel global checkpoint protocol, so called address log based protocol(ALBP), based on an asynchronous protocol. It is a platform based protocol to reduce power consumption, performance overhead, and memory overhead which are the most of consideration in wireless sensor network.

• The KIPS Transactions:PartA
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• v.11A no.3
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• pp.139-148
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• 2004

The number of applications of small embedded systems such as PDAs, electronic note books, etc. based on Kinux, have increased. Due to the monolithic characteristic of Linux kernel, it is not suitable to satisfy the various kinds of embedded application requirement. To assist the shortcoming of monolithic kernel, we implement uJFFS 113th file system as an application program process which runs in user space. This solution consists of a file system and a flash device driver, and makes Linux kernel smaller by separating the file system from the kernel. uJFFS consists of ujffs_fs that plays a part of file system and ujffs_drv that controls a flash device. Which provides the same user interface as Linux does. A Device driver for the physical device is implemented in user pace, which prevents kernel failures from file system errors. So uJFFS can increase stability of the system.

• The Transactions of the Korea Information Processing Society
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• v.3 no.7
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• pp.1719-1726
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• 1996

In the OR-parallel execution of logic programs, binding environments have a critical impact on the performance. Particularly, this is true for distributed execution on parallel systems with a non-single address space. The reason is that in such systems, the remote accesses across processing elements deteriorate the performance. To solve this problem, some binding methods were previously proposed specifically for a non-single address space. However, compared with the binding methods for a single address space, they are far less efficient due to the overhead of newly introduced operations such as environment closing and back-unification, In this paper, we propose a new binding environment is a hybrid that combines both the binding methods for a single address space and those for anon-single address space. It acomplishes high efficiency by making closing operations unnecessary both at unification and at back-unification, while mainthing the restricted accesses.

• Journal of Korea Multimedia Society
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• v.7 no.8
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• pp.1120-1130
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• 2004

Distributed Denial-of-Service(DDoS) attack prevent users from accessing services on the target network by spoofing its origin source address with a large volume of traffic. The objective of IP Traceback is to determine the real attack sources, as well as the full path taken by the attack packets. Existing IP Traceback methods can be categorized as proactive or reactive tracing. Existing proactive tracing scheme(such as packet marking and messaging) prepares information for tracing when packets are in transit. But, these scheme require additional network overhead. In this paper, we propose a "advanced Traceback" mechanism, which is based on the modified Pushback system with secure router mechanism. Proposed mechanism can detect and control DDoS traffic on router and can generate marked packet for reconstructing origin DDoS attack source, by which we can diminish network overload and enhance Traceback performance.