• Journal of Navigation and Port Research
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• v.47 no.1
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• pp.10-17
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• 2023

A series of studies on the development of autonomous surface ships have been promoted in domestic and foreign countries. One of the main technologies for the development of autonomous ships is path-following control, which is closely related to securing the safety of ships at sea. In this regard, the path-following performance of an autonomous ship should be first evaluated at the design stage. The main aim of this study was to develop a visual and quantitative evaluation method for the path-following control performance of an autonomous ship at the design stage. This evaluation technique was developed using a computational fluid dynamics (CFD)-based path-following control model together with a line-of-sight (LOS) guidance algorithm. CFD software was utilized to visualize waves around the ship, performing path-following control for visual evaluation. In addition, a quantitative evaluation was carried out using the difference between the desired and estimated yaw angles, as well as the distance difference between the planned and estimated trajectories. The results demonstrated that the ship experienced large deviations from the planned path near the waypoints while changing its course. It was also found that the fluid phenomena around the ship could be easily identified by visualizing the flow generated by the ship. It is expected that the evaluation method proposed in this study will contribute to the visual and quantitative evaluation of the path-following performance of autonomous ships at the design stage.

• Journal of Korean Society of Disaster and Security
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• v.13 no.1
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• pp.59-75
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• 2020

This study is a case study that applied 'UNDRR's Urban Disaster Resilience Scorecard', an evaluation tool necessary for Incheon Metropolitan City to be certified as an international safe city. I would like to present an example that the results derived from this scorecard contributed to the Incheon Metropolitan City Disaster Reduction Plan. Of course, the Disaster Resilience Scorecard can't provide a way to improve the resilience of every disaster facing the city. However, it is to find the weakness of the resilience that the city faces, and to propose a solution to reduce the city's disaster risk. This is to help practitioners to recognize the disaster risks that Incheon Metropolitan City faces. In addition, the solution recommended by UNDRR was suggested to provide resilience in areas vulnerable to disasters. It was confirmed that this process can contribute to improving the disaster resilience of Incheon Metropolitan City. UNDRR has been spreading 'Climate Change, Disaster-resistant City Creation Campaign', aka MCR (Making Cities Resilient) Campaign, to cities all over the world since 2010 to reduce global cities' disasters. By applying the disaster relief guidelines adopted by UNDRR, governments, local governments, and neighboring cities are encouraged to collaborate. As a result of this study, Incheon Metropolitan city's UN Urban Resilience Scorecard was evaluated as a strong resilience field by obtaining scores of 4 or more (4.3~5.0) in 5 of 10 essentials; 1. Prepare organization for disaster resilience and prepare for implementation, 4. Strong resilience Urban development and design pursuit, 5. Preservation of natural cushions to enhance the protection provided by natural ecosystems, 9. Ensure effective disaster preparedness and response, 10. Rapid restoration and better reconstruction. On the other hand, in the other five fields, scores of less than 4 (3.20~3.85) were obtained and evaluated as weak resilience field; 2. Analyze, understand and utilize current and future risk scenarios, 3. Strengthen financial capacity for resilience, 6. Strengthen institutional capacity for resilience, 7. Understanding and strengthening social competence for resilience, 8. Strengthen resilience of infrastructure. In addition, through this study, the risk factors faced by Incheon Metropolitan City could be identified by priority, resilience improvement measures to minimize disaster risks, urban safety-based urban development plans, available disaster reduction resources, and integrated disasters. Measures were prepared.

• Journal of the Korean Institute of Landscape Architecture
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• v.47 no.5
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• pp.14-27
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• 2019

This study presents a plan for a memorial park that respects the characteristics based on the historical facts for the concept of space of the Gwangju Hospital of Korea Army and the location of the 505 Security Forces, which were designated as historic sites after the 5-18 Democratization Movement. The Gwangju Metropolitan City as it is the location of the 5-18 historic sites, is taking part in the 5-18 Memorial Project, and plans to establish a city park recognizing the historic site of the 5-18 Democratization Movement, which has been preserved only as a memory space to this point. The park is promoting a phased development plan. This study suggests that the 5-18 historic sites can be modernized and that social consensus can establish the framework of the step-by-step planning and composition process to ensure the plans for the space heals wounds while preserving the history. In this paper, we propose a solution to a problem. We solve the approach for space utilization through an analysis of precedent research and planning cases related to park planning at historical sites. In addition to exploring the value of the site, we also describe the space utilization strategy that covers the historical characteristics and facts while maintaining the concept of park planning. As a result of the research, the historic site of the Gwangju Hospital of Korea Army is planned as a park of historical memory and healing in order to solve the problems left behind by the 5-18 Democratization Movement. The historic site of the 505 Security Forces was selected as an area for historical experiences and a place for learning that can be sympathized with by future generations of children and adolescents in terms of expanding and sustaining the memory of the 5-18 Democratization Movement. In the planning stage, the historical sites suggested the direction of space utilization for representation as did the social consensus of citizens, related groups, and specialists. Through this study, we will contribute to construction of a memorial park containing historical values in from 5-18 historic sites. It is meaningful to suggest a direction that can revitalize the life of the city as well as its citizen and can share with the history with future generations beyond being a place to heal wounds and keep alive the memory of the past.

• Korea Science and Art Forum
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• v.37 no.4
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• pp.149-159
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• 2019

This research was started to identify the color status of signboards at the target site and suggest the direction of improvement for the signboard project in Dongsang-dong, Jongno-gil, a central area of the old city center of Gimhae. The area under study forms a depressed street atmosphere with old facilities, and is a typical type of old city center sign that needs to be rebuilt. The purpose of this study is to investigate prior research related to signage and similar signboard improvement cases, and then to identify the current status of colors by sorting out the casting, auxiliary and highlighted colors through the survey of the color of the signboard in the target area, and to propose a desirable direction for the future sign business based on the basis of these findings. This paper divided the target sections by industry and conducted a color analysis of signboards. The results and contents of the research are as follows. First, cast-colored signboards in general businesses showed a variety of primary color distributions with high L* values, on average, with high intensity and high chromaticity. Second, the auxiliary colors were mostly white or black in color-free, making a contrast between the casting colors. Third, the highlight was that a* value showed a high distribution in positive water plus and was mainly distributed in obsolescence, such as red or yellow, and color was used to reflect the characteristics of each store. However, the stores in the entire section lack unity because they were using colors that were higher in color than middle colors, which was causing the street's aesthetic look to be undermined. Based on the results of these studies, it is thought that the future color scheme for Gimhae's signature improvement project will limit the number of colors to a certain extent and give a sense of security and visual comfort to the use of colorlessness and obscurity around the representative colors of Gimhae.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.3 no.1
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• pp.5-25
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• 2009

In recent years the popularity of multi-hop wireless networks has been growing. Its flexible topology and abundant routing path enables many types of applications. However, the lack of a centralized controller often makes it difficult to design a reliable service in multi-hop wireless networks. While packet routing has been the center of attention for decades, recent research focuses on data discovery such as file sharing in multi-hop wireless networks. Although there are many peer-to-peer lookup (P2P-lookup) schemes for wired networks, they have inherent limitations for multi-hop wireless networks. First, a wired P2P-lookup builds a search structure on the overlay network and disregards the underlying topology. Second, the performance guarantee often relies on specific topology models such as random graphs, which do not apply to multi-hop wireless networks. Past studies on wireless P2P-lookup either combined existing solutions with known routing algorithms or proposed tree-based routing, which is prone to traffic congestion. In this paper, we present two wireless P2P-lookup schemes that strictly build a topology-dependent structure. We first propose the Ring Interval Graph Search (RIGS) that constructs a DHT only through direct connections between the nodes. We then propose the ValleyWalk, a loosely-structured scheme that requires simple local hints for query routing. Packet-level simulations showed that RIGS can find the target with near-shortest search length and ValleyWalk can find the target with near-shortest search length when there is at least 5% object replication. We also provide an analytic bound on the search length of ValleyWalk.

• The Journal of the Korea Contents Association
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• v.9 no.4
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• pp.131-141
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• 2009

An increasing variety of malware, such as worms, spyware and adware, threatens both personal and business computing. Remotely controlled bot networks of compromised systems are growing quickly. This paper proposes an intrusion detection system based outflow traffic analysis. Many research efforts and commercial products have focused on preventing intrusion by filtering known exploits or unknown ones exploiting known vulnerabilities. Complementary to these solutions, the proposed IDS can detect intrusion of unknown new mal ware before their signatures are widely distributed. The proposed IDS is consists of a outflow detector, user monitor, process monitor and network monitor. To infer user intent, the proposed IDS correlates outbound connections with user-driven input at the process level under the assumption that user intent is implied by user-driven input. As a complement to existing prevention system, proposed IDS decreases the danger of information leak and protects computers and networks from more severe damage.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.14 no.3
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• pp.715-722
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• 2010

This paper describes a hardware design of hash function processor which implements Korean Hash Algorithm Standard HAS-160. The HAS-160 processor compresses a message with arbitrary lengths into a hash code with a fixed length of 160-bit. To achieve high-speed operation with small-area, arithmetic operation for step-operation is implemented by using a hybrid structure of 5:3 and 3:2 carry-save adders and carry-select adder. It computes a 160-bit hash code from a message block of 512 bits in 82 clock cycles, and has 312 Mbps throughput at 50 MHz@3.3-V clock frequency. The designed HAS-160 processor is verified by FPGA implementation, and it has 17,600 gates on a layout area of about $1\;mm^2$ using a 0.35-${\mu}m$ CMOS cell library.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.10 no.7
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• pp.1237-1245
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• 2006

This paper presented a hardware implementation of ARIA, which is a Korean standard l28-bit block cryptography algorithm. In this work, ARIA was designed technology-independently for application such as ASIC or core-based designs. ARIA algorithm was fitted in FPGA without additional components of hardware or software. It was confirmed that the rate of resource usage is about 19% in Altera EPXAl0F1020CI and the resulting design operates stably in a clock frequency of 36.35MHz, whose encryption/decryption rate was 310.3Mbps. Consequently, the proposed hardware implementation of ARIA is expected to have a lot of application fields which need high speed process such as electronic commerce, mobile communication, network security and the fields requiring lots of data storing where many users need processing large amount of data simultaneously.

• Journal of KIISE:Information Networking
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• v.32 no.4
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• pp.443-451
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• 2005

Stateful inspection devices must maintain flow information. These devices create the flow information also for network attack packets, and it can fatally inflate the dynamic memory allocation on stateful inspection devices under network attacks. The memory inflation leads to memory overflow and subsequent performance degradation. In this paper, we present a guideline to set the flow entry timeout for a stateful inspection device to remove harmful embryonic entries created by network attacks. Considering Transmission Control Protocol (TCP) if utilized by most of these attacks as well as legitimate traffic, we propose a parsimonious memory management guideline based on the design of the TCP and the analysis of real-life Internet traces. In particular, we demonstrate that for all practical purposes one should not reserve memory for an embryonic TCP connection with more than (R+T) seconds of inactivity where R=0, 3, 9 and $1\leqq{T}\leqq{2}$ depending on the load level.

• Proceedings of the KSR Conference
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• 2011.10a
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• pp.2090-2100
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• 2011

Railway rail fastening system is the critical device which gives big influences to not only the vehicle driving stability and the orbit's structural stability against the impulsive load, but also the noise vibration and the ride comfort. As a part of the low-carbon green growth, the importance of the railroad industry is getting highlights on its excellent energy-efficiency and eco-friendliness. However, so far the Korea's domestic rail fastening system technology is not so good and the technical reliance to abroad is very heavy. In this study, we conducted comparative analysis on the rail fastening system with new and used one of the same type. And those systems are imported by Seoul Metro and are being used by it. With this basis, we developed the components and the materials and then, established the durability assessment methods appropriate to the Korean domestic circumstances. And through the reliability qualification test on the 7 parts of the rail fastening system, we've improved the reliability and guaranteed the 15 years of service lifetime. ($B_{10}Life15$) Establishment and standardization of Reliability Standard on the parts of the rail fastening system such as anti-vibration pads, guide-plate, screw spike made it possible to perform the internationally fair assessment. And it is thought that we can satisfy the manufactures' and consumers' needs of cost-cutting and qualification security by shortening of assessment period on rail fastening system.