• Journal of Biomedical Engineering Research
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• v.22 no.5
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• pp.439-448
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• 2001

This paper considers the acoustical characteristics of the closing click sounds of the mechanical valves employed in an implantable biventricular assist device (BYAD) and their re1evance to the Physical states of the valved. Bj rk Shiley Convexo Concave tilting disk valve was chosen for the study and acoustic measurement was made for the BYAD operated in a mock circulatory system as well as implanted in an animal (sheep). In the BYAD operated in the mock circulatory system. three different states of the valve were examined, ie. normal. mechanically damaged. pseudo-thrombus attached. Microphone measurement for the BVAD implanted in the animal was carried out for five days at a regular time interval from one day after implantation. Characteristic spectrum of the sound from the valve was estimated using Multiple Signal Classification (MUSIC) in which the optimal order was determined according to Bayesian Information Criterion (BIC) . It was observed that the mechanical damage of the valve resulted in changes of the structure of the acoustic spectrum. In contrast. the thrombus formed on the valve did not change much the basic structure of the spectrum but brought about altering the spectral Peak frequencies and energies. Maximum spectral Peak (MSP) with the greatest energy was seen at 2 kHz for the normal valve and it was shifted to 3 kHz for the calve attaching the Pseudo-thrombus. Unlike the normal valve, strong spectral Peak appeared around 7 kHz in the sound from the valve mechanically damaged. In the case of the BYAD implanted in the animal. as the thrombus grew, acoustic energy was reduced relatively more in the low frequency components (〈 2 kHz) and the frequencies of the 1st, 2nd and 3rd MSP were increased little. The thrombus formation would result in reduction in both the variability of the 1st, 2nd and 3rd MSP and the value of the BIC optimal order.

• Journal of the Korean Association of Geographic Information Studies
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• v.14 no.3
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• pp.203-222
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• 2011

The characteristics of flood damages have been increasingly strengthened and take the form of unpredictable and unusual weather phenomena caused by climate change and climate anomalies. To prevent inundation damage caused by breach of hydraulic structure such as dam or levee, and trouble of drainage of inner basin, the prediction necessity of flood inundation area, flood risk analysis, and drawing flood risk maps have been on the rise, and the national flood risk maps have been produced. In this study, the quantitative flood vulnerability analysis was performed, which represents population living within flood-affected areas, types of economic activities, facilities affected by flood, in order to extend flood risk mapping from simple hazard concept into risk based idea. By applying it to Nakdong River basin, the flood vulnerability indices were estimated to draw flood risk maps subdivided into administrative districts. The result of this study can be applied to establish the disaster prevention measures and priority decision of disaster prevention project.

• Journal of the Korean Association of Geographic Information Studies
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• v.14 no.3
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• pp.150-162
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• 2011

For the period between 1991 and 2009, the annual average of 448 forest fires occurred in Korea. Above all, approximately 94% of the total fires frequently occurred during the spring and fall seasons. Therefore, we need to minimize the damage of forest fire and manage them systematically. In this study, we analyzed the spatio-temporal distribution patterns for the frequency of forest fire occurrences by each city and gun during dry season between 1990s and 2000s using GIS. Then we compared to analyze the frequency of forest fire occurrence by ten-day intervals in 2000s with that in 1990s. As a result of analysis, early April showed the highest frequency of forest fire occurrence in both 1990s and 2000s. Compared to the 1990s and 2000s, the regional change of forest fire showed the most frequent fire events around Chungcheong province. Especially extra 27 fires increased in Daejeon city, and the second most frequent fire had more than 10 fires in Jeolla province and Incheon. However, the number of fire frequency decreased by 12 fires at the end of April in Hongcheon-gun(the province of Gangwon). This is the largest drop over the study period. We consider that this paper will utilize usefully to establish regional counterplan for forest fire prevention by understanding regional forest fire patterns from seasonal change.

• Journal of the Korean Geotechnical Society
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• v.17 no.6
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• pp.111-121
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• 2001

Rockfall protection fences are used for diminishing rockfall damage in roads side slopes. In order to install the fences in effective way, the conditions of rock slopes and total predicted impact energy of fa11ing rock should be considered. However, the fences have been constructed without any consideration for lithology, height and slope angle of rock slope in Korea. In addition, the information about the performance of the protection fences, which should be evaluated by in-situ test or laboratory test in order to check out the practical use in the field, is not available. Therefore, in design manual for the rockfall protection fence, the specific details for the installation of this type of fence are not provided yet. The full sized rockfall in situ test was carried out for the calculation of falling energy of rock and the evaluation of the maximum energy absorbing capacity of fence. For this test, the rock slopes whose heights are about 20 m and dip angle of 65 degree, have been chosen. This is because those geometries are mean height and slope angle of most road cut slopes along Korean national highway. Based on the preliminary simulation procedure, four different sizes of concrete ball (0.7, 1.3, 2.3 and 4.3 ton) were prepared and flour different types of protection fence were constructed. The results of this test provide information about the maximum energy absorbing capacity of the fence, kinetic energy of rockfall and restitution coefficient, and these results can be utilized in the establishment of rockfall fence design and construction manual.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.28 no.5
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• pp.1119-1127
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• 2018

Most of the cyber attacks are caused by malicious codes. The damage caused by cyber attacks are gradually expanded to IoT and CPS, which is not limited to cyberspace but a serious threat to real life. Accordingly, various malicious code analysis techniques have been appeared. Dynamic analysis have been widely used to easily identify the resulting malicious behavior, but are struggling with an increase in Anti-VM malware that is not working in VM environment detection. On the other hand, static analysis has difficulties in analysis due to various packing techniques. In this paper, we proposed malware classification techniques regardless of known packers or unknown packers through the proposed model. To do this, we designed a model of supervised learning and unsupervised learning for the features that can be used in the PE structure, and conducted the results verification through 98,000 samples. It is expected that accurate analysis will be possible through customized analysis technology for each class.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.17 no.2
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• pp.423-430
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• 2013

Recently, the personal identification technologies using vein pattern of back of the hand, palm, and finger have been developed actively because it has the advantage that the vein blood vessel in the body is impossible to damage, make a replication and forge. However, it is difficult to extract clearly the vein region from captured vein images through common image prcessing based region segmentation method, because of the light scattering and non-uniform internal tissue by skin layer and inside layer skeleton, etc. Especially, it takes a long time for processing time and makes a discontinuity of blood vessel just in a image because it has non-uniform illumination due to use a locally different adaptive threshold for the binarization of acquired finger-vein image. To solve this problem, we propose illumination normalization based fast method for extracting the finger-vein region. The proposed method has advantages compared to the previous methods as follows. Firstly, for remove a non-uniform illumination of the captured vein image, we obtain a illumination component of the captured vein image by using a low-pass filter. Secondly, by extracting the finger-vein path using one time binarization of a single threshold selection, we were able to reduce the processing time. Through experimental results, we confirmed that the accuracy of extracting the finger-vein region was increased and the processing time was shortened than prior methods.

• The KIPS Transactions:PartC
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• v.8C no.5
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• pp.629-636
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• 2001

Network is changed from voice-based network into multimedia-based network by development of communication technology and multimedia service. We need a large bandwidth for multimedia service. The optical fiber is a more suitable medium than existing copper-based cable for large bandwidth. But, it is so expensive than copper-based cable. So, Minimizing total cost becomes a more important concept. In order to construct a minimum cost network, we have to consider existing conduits in network. On the other hand, optical fiber network allows that larger amount of traffic can be transmitted than copper-based network does. However, a failure of a node or link can make a serious damage to the network service. Thus, we have to get multiple paths to support continuous service even if a loss of failure occurs in some point of the network. The network survivability problem is to design the network that can provide reliable service to customers anytime with minimum total cost. In an existing solution of the network survivability problem with conduits, a conduit is considered only one time. But, the conduit is reusable if the network satisfies the required survivability. Proposed algorithm can more effectively considered already existed conduit. Network survivability and edge cost is predetermined. The proposed algorithm finds the best solution by conduit sharing within the limits of network survivability. According to the simulation result, the proposed method can decrease 7% of total cost than an existing method by effective conduits adaption.

• The Journal of the Korea Contents Association
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• v.14 no.11
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• pp.644-656
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• 2014

In recent years, a series of large-scale disastrous accidents have been occurred frequently both in public and private sector. Such disasters become catastrophe due to poor early response and delayed prompt rescue. Damage from catastrophe could have been drastically reduced or minimized with effective response and recovery management. The smart phone-based mobile applications have important potentials in providing solutions for the effective response and recovery management. Mobile applications can greatly improve risk communication in case of disasters by integrating process of exchange information and data on risk among risk evaluators, risk managers, and other interested parties. In this light of potentials, this study investigates the measures and management to better manage early responses and to effectively deal with domestic disaster-related of the status of public applications service, and utilization. This study examines how disaster applications can be better used and how effective information dissemination through applications could help the post-disaster management process. Based on this findings, it proposes a guideline of effective disaster-related applications by public sector for the future development of actual services and activation solutions. The results show that "User Promptness Side" and "Content Believability Side" factors found to be the two most significant factors in the disaster-related applications by public sector. Discussion and implications are discussed.

• Korean Journal of Remote Sensing
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• v.30 no.1
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• pp.127-136
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• 2014

When the mouth of the Nakdong River, opens its floodgate, thousands of tons of litter should flown into the South Sea, moving towards nearby coast, thus causing serious social and economic damage. For this reason, in the present study, research was performed on one certain area in northeast coast of Geoje island, which is assumed as area damaged due to rainy season and typhoon in 2012, and research for trace of movement route was implemented by using buoy to identify characteristic of movement of floating debris caused from Nakdong River. Flows related to the movement of floating debris was also identified by analyzing ocean meteorological environment. As a result of the study, total 40 tons of litter composed of grasses and trees(or plants litter) were flown into Heungnam beach on 16th, Jul which is the rainy season. Plus, the location tracking buoy, which was dropped when the typhoon SANBA was coming, was passed by southern sea of Gadeok-do and was flown into Geoje beach 1 ~ 2 days after it was dropped. The wind direction was mostly northeasterly wind around the Geoje beach at the time the buoy and floating debris were flown into northeast coast and there was common sea surface currents which was flowing into the coast.

• Korean Security Journal
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• no.25
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• pp.109-130
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• 2010

As many countries in the world including the Republic of Korea have used all their national resources in the accelerating economic information warfare, illegal leakage of industrial technologies and information has increased rapidly. The costs required for damage prevention from 2007 to 2008 are estimated at approximately KRW 180 trillion which is expected to increase gradually in future. Because the tricks of leaking key technologies are also getting increasingly systematized, sophisticated and bigger, e.g., simple theft at the individual level or the conspiracy of all the staff taking part in the research activities, we should pay special attention to technology security in addition to technology development. While there are several factors affecting such the brain drain, they usually include personal, social, political and cultural factors, for instance, very heavy educational expenditure of children compared to relatively low pay, the speedy labor market circulation for experienced personnel, or political restrictions on researches. In this context, as part of efforts made to prevent the outflow of core personnel, individual companies and research institutes should establish systematically appropriate core personnel management systems for their own organizational or business goals and principles which are intented to ensure to give better treatment and benefit to core personnel and to exercise closer supervision over them. Furthermore, the conventional personnel management system should be radically and flexibly improved in the manner of encouraging the core personnel returning to the organization to combine their external experiences with practices, instead of penalizing them. At the same time, it is necessary to train and educate core personnel through mutual collaboration and in-house training facilities as well as external academic programs operated jointly at the level of the industry. Finally, as the issues concerning the outflow of core personnel are not just problems of relevant companies and other advanced countries have devoted their best efforts to secure their own key technologies at the national level, it is urgent for the industry and the competent authorities to cooperate closely.