• Journal of Korean Tunnelling and Underground Space Association
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• v.16 no.1
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• pp.1-11
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• 2014

In order to determine the optimal number of monitoring points in single-track tunnel lining, this thesis compares and evaluates the results of two cases: when the tunnel lining is modeled into a simple beam form and then is applied to 1) the tunnel lining inverse analysis program, and to 2) the commercially-used program. The displacement and stress of specific tunnel lining cross-sections are determined by entering the load conditions into the commercially-used program for tunnel interpretations. In doing so, two cases were assumed: where a symmetrically-distributed load was acting upon the tunnel lining of a single-track tunnel and where an asymmetrically-distributed load was in action. By comparing the computed displacement with the stress and displacement determined by entering side numbers 3, 5, and 7 into the tunnel lining inverse analysis program, the optimal number of monitoring points is determined. From the results of the research, it can be inferred that the number of monitoring points needs to be at least 5 points, considering the efficiency of monitoring in practice and the loss-and-damage rate of tunnel monitoring.

• Journal of the Korea Convergence Society
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• v.11 no.11
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• pp.1-7
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• 2020

Android apps are mostly distributed as an apk files, and when the apk file is uncompressed, resource files such as xml files, images, and sounds related to app design can be extracted. If the resources of banking or finance-related apps are stolen and fake apps are distributed, personal information could be stolen or financial fraud may occur. Therefore, it is necessary to make it difficult to steal the design as well as the code when distributing the app. In this paper, we implemented a tool to convert the xml file into Java code and obfuscate using the Proguard, and evaluated the execution performance. If the layout obfuscation technique proposed in this paper is used, it is expected that the app operation performance can be improved and the illegal copying damage caused by the theft of the screen design can be prevented.

• Convergence Security Journal
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• v.16 no.5
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• pp.11-16
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• 2016

In modern society, the development of Information and Communication Technology has given people a lot of opportunities. But on the other side cyber attack also gives enormous damage to people. Recently Korea has become the target of cyber attack. The threat of it is growing. Especially North Korea has committed hostile actions against South Korea. North Korea has recently attacked the computer networks of South Korea's important national facilities. The types of North Korea's cyber attacks include the followings. First, if we see it with the viewpoint of software, it tries to destroy or control the Internet, infects the networks with viruses, worms, Trojan Horse and Distributed Denial of Service. I suggest the following to solve the problem. First, South Korea should unify the organizations to respond to the attacks of North Korea, as North Korea has a unified organization for the cyber attack. Second, they should think about the establishment of "Cyber Terrorism Prevention Act" to systematically respond to the software attacks.

• The KIPS Transactions:PartC
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• v.14C no.1 s.111
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• pp.45-54
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• 2007

As one of the most threatening attacks, DDoS attack makes distributed multiple agents consume some critical resources at the target within the short time, thus the extent and scope of damage is serious. Against the problems, the existing defenses focus on detection, traceback (identification), and filtering. Especially, in the hierarchical networks, the traffic congestion of a specific node could incur the normal traffic congestion of overall lower nodes, and also block the control traffic for notifying the attack detection and identifying the attack agents. In this paper, we introduce a DDoS attack tolerant network structure using a hierarchical overlay for hierarchical networks, which can convey the control traffic for defense such as the notification for attack detection and identification, and detour the normal traffic before getting rid of attack agents. Lastly, we analyze the overhead of overlay construction, the possibility of speedy detection notification, and the extent of normal traffic transmission in the attack case through simulation.

• Journal of Sasang Constitutional Medicine
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• v.14 no.3
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• pp.97-113
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• 2002

Objective To study the effectiveness of Yuldahansotang against Allergic Contact Dermatitis, the change of cutaneous shape, histochemistry, immunohistochemistry and distribution of apoptotic cells was researched. materials and methods 4-month-old rats were divided into three groups of 10. One is a contrastive group which has applied Acetone olive oil only. Another is ACD group which has intentionally activated Allergic Contact Dermatitis by DNCB. And the other is YST group which has given medication of Yangkyuksanhawtang extract. Each group of mice were observed after 24, 48 and 72 hours. results 1. With the result of Contact hypersensitivity assay, YST group shows appreciably less ear swelling than ACD group. 2. Comparing YST and ACD groups to each other regarding general change of skin, YST group shows less hyperplasia of epidermis, less migration of inflammatory cells and less damage of epidermis than ACD group. 3. Regarding the change of collagen fiber, ACD group has appeared to be low in number of collagen fiber while YST shows similarity with the contrastive group. 4. In dermis YST group has showed lower number of mastocyte than ACD group and is granulated type. 5. In dermis YST group has showed less MAC-1,IL-1, $IL-2R-{\alpha}$, ICAM-1 and VCAM-1 than ACD group. 6. The distribution of apoptotic cells has appeared littler in YST group than in ACD 7. Among signal molecule of apoptosis Bcl-2 has distributed more in YST group than ACD group and Bax and Fas has distributed less in YST group than ACD group.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.13 no.1
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• pp.81-87
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• 2020

Recently, the network configuration is being rapidly changed to enable easy and free network service configuration based on SDN/NFV. Despite the many advantages and applications of SDN, many security issues such as Distributed Denial of Service (DDoS) attacks are being constantly raised as research issues. In particular, the effectiveness of DDoS attacks is much faster, SDN is causing more and more fatal damage. In this paper, we propose an entropy-based technique to detect and mitigate DDoS attacks in SDN, and prove it through experiments. The proposed scheme is designed to mitigate these attacks by detecting DDoS attacks on single and multiple victim systems and using time - specific techniques. We confirmed the effectiveness of the proposed scheme to reduce packet loss rate by 20(19.86)% while generating 3.21% network congestion.

• Journal of the Society of Naval Architects of Korea
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• v.53 no.6
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• pp.447-455
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• 2016

Precise propulsion shafting alignment of ships is very important to prevent damage of its support bearings due to excessive reaction forces caused by hull deflection, forces acted on propeller and crankshaft, and so forth. In this paper, a new iterative shafting alignment calculation procedure considering the interaction between shaft deflection and oil film pressure of Sterntube Journal Bearing (SJB) bush with single or multiple slopes is proposed. The procedure is based on a pressure analysis to evaluate distributed equivalent support stiffness of SJB by solving Reynolds equation and a deflection analysis of shafting system by a finite element method based on Timoshenko beam theory. SJB is approximated with multi-point biaxial elastic supports equally distributed to its length. Their initial stiffness values are estimated from dynamic reaction force calculated by assuming SJB as single rigid support. Then, the shaft deflection and the support stiffness of SJB are sequentially and iteratively calculated by applying a criteria on deflection variation between sequential calculation results. To demonstrate validity and applicability of the proposed procedure for optimal slope design of SJB, numerical analysis results for a shafting system are described.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.18 no.2
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• pp.65-72
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• 2019

In long freight trains, there is a brake time delay in neighboring freight cars, which causes damage and fractures in the couplers, especially at their knuckle. A problem in the couplers of the cars can cause derailment and damages of human life and property. In this study, maximum forces on the couplers are studied when a long freight car brakes with the brake delay time and coupler gap. We make a dynamic model of 50 freight cars and couplers, applying contact between the couplers and a characteristic curve to express the force and displacement of the buffers using SIMPACK, which is a multi-body dynamics program. We use EN 14531-2, which is a standard of freight car brakes, to verify the dynamic model. Then, we compare the analyzed impact force with the coupler knuckle standard after applying the two carriages of a locomotive in the model based on the dispersed double head control system. The result shows that all coupler gap conditions satisfy the infinite lifetime of the material when the brake delay time is 0.1 second.

• Journal of Industrial Convergence
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• v.20 no.11
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• pp.57-63
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• 2022

If ECU data, which is responsible for collecting and processing data such as sensors and signals of automobiles, is manipulated by an attack, it can cause damage to the driver. In this paper, we propose a system that verifies the integrity of automotive ECU data using blockchain. Since the car and the server encrypt data using the session key to transmit and receive data, reliability is ensured in the communication process. The server verifies the integrity of the transmitted data using a hash function, and if there is no problem in the data, it is stored in the blockchain and off-chain distributed storage. The ECU data hash value is stored in the blockchain and cannot be tampered with, and the original ECU data is stored in a distributed storage. Using the verification system, users can verify attacks and tampering with ECU data, and malicious users can access ECU data and perform integrity verification when data is tampered with. It can be used according to the user's needs in situations such as insurance, car repair, trading and sales. For future research, it is necessary to establish an efficient system for real-time data integrity verification.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.23 no.5
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• pp.45-58
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• 2020

This study was conducted to comprehend the spatial distribution characteristics, habitats and appearances of Hydropotes inermis by using the biotope mapping in Daebudo Island, Ansan-si. The result is base data to understand status and manage potential inhabitation of Hydropotes inermis in Daebudo Island through the Maximum Entropy model. The study used 105 traces from the primary investigation and 452 traces in the secondary investigation. The biotope types were distinquished Hydropotes inermis habitats largest from the order of natural forest (15.1%), natural coast (13.7%), marshy cultivated land (12.6%), and dry cultivated land (11.7%), and from the inhabitation trace results. Hydropotes inermis appearanced biotope types were the greatest in the order of cultivated land (49.73%) > forest (18.85%) > coast (7.00%) > grassland (6.28%). Since forests in Daebudo Island have low slope and altitude, it was concluded that Hydropotes inermis would live in most of the forests. A high number of Hydropotes inermis was found to appear in areas where the grassland is formed including cultivated lands (include unused paddies and fields) and marshy grasslands, which would result in direct damage of crops. According to the Maxent modeling analysis that used location information of Hydropotes inermis, the AUC value was 0.635 based on the ROC curve. In Daebudo Island, areas with over 0.635 potential inhabitation value are distributed all over the place, and it was concluded that each population would have a different scope of influence and home range. Hydropotes inermis living in Daebudo Island have high habitat suitability mainly around the cultivated lands near the roads, but due to the bare lands and roads, it is expected that their habitats would be fragmented and damaged, which would have a direct and indirect effect in maintaining the Hydropotes inermis population. Also, considering habitat disturbance, diverse methods for reducing damage including capturing some individuals within the limit that does not disperse Hydropotes inermis population in Daebudo Island must be carried out.