• Title/Summary/Keyword: 지역 간 전파

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Extremal Dependence in Asia Pacific Exchange Markets (EVT-Copula 모형을 이용한 아시아 외환시장 간 극단적 의존성에 관한 연구)

  • Kim, Tae-Hyuk;Zhao, Hui-Jing
    • The Korean Journal of Financial Management
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    • v.23 no.1
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    • pp.193-225
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    • 2006
  • The purpose of this paper is to analyze contagion in Asian foreign exchange markets using Extreme Value Theory and Copula. Our application deals with asymptotic dependence of daily exchange rate return for a sample of eight countries over period 1997.1.1-2005.4.13. The empirical results are summarized as follows. Firstly, Gumbel Copula is a good model to our data according to the value of AIC. Secondly, the extremal dependence between East Asian crisis countries became lower in the post crisis period than the crisis period. Thirdly, It seemed that high extremal dependence exists between East Asian countries with Singapore. Fourthly, the tail dependence between Indonesia, Malaysia, Thailand, Philippine became higher in the crisis period than the total period and post crisis period. Fifthly, the fact that the extremal dependence between Korea and Indonesia, Malaysia, Thailand, Philippine did not increase during the Asian Financial Crisis showed that the contagion effect was not the reason of the Korea's Fiancial Crisis. Sixthly, the extremal dependence between Asian exchange markets was not very high while comparing with the European exchange markets.

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Development of Radio Spectrum Monitor for HF Communication (단파 스펙트럼 수신 모니터링 시스템 개발)

  • Park, Sung Won;Kim, Young Yun
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.26 no.9
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    • pp.821-827
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    • 2015
  • Electromagnetic waves which are emitted from the Sun due to solar flare explosion can cause failures in HF radio communications in the day-side area of the Earth, that is so-call as Radio Blackouts. The international scale representing the severity of the Radio Blackouts is determined by the solar X-ray flux which is measured by United States Geostationary Operational Environmental Satellite. However, the scale is not always applicable to HF communication users in the different area on the Earth, because the HF communication effects depend not only on the X-ray strength but also on the subsolar point location. To solve this problem, we developed a HF radio spectrum monitoring system utilizing a spectrum analyzer. This system conducts a real-time measure of the HF spectrum, and automatically calculates signal to noise ratios and the occurrences of the HF blackouts as comparing with the interference level which is described from the ITU recommendation.

Geophysical Study Through Infrasound Observation (인프라사운드 관측을 통한 지구물리학적 연구)

  • Che, Il-Young;Jeon, Jeong-Soo
    • Economic and Environmental Geology
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    • v.39 no.4 s.179
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    • pp.495-505
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    • 2006
  • Atmospheric infrasound is defined as low frequency inaudible sound waves generated from natural phenomena and human activities. One property of long-distance travelling of infrasound makes it possible to detect the wave propagated from remote sound sources and to understand many geophysical phenomena generating it. Recently, advanced global infrasound sensor arrays are being deployed to monitor the clandestine nuclear test and to study geophysical phenomena in the world. In Korea, five seismo-acoustic arrays consisting of co-located seismometer and micro-barometer have been operated to discriminate the artificial explosions from the natural earthquakes in and around the Korean Peninsula. In addition to the discrimination purpose, these ways also record distinct infrasonic signals from natural phenomena on global scale such as large earthquake, bolide event, volcanic explosion, typhoon, and so on. As a new frontier in monitoring the earth, infrasound is being applied to understand various phenomena in and above the earth's surface.

YouTube and Girls' Generation Fandom (유투브와 소녀시대 팬덤)

  • Shim, Doo-Bo;Noh, Kwang-Woo
    • The Journal of the Korea Contents Association
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    • v.12 no.1
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    • pp.125-137
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    • 2012
  • In this paper we draw from recent theoretical discussions of fan culture and the new media technologies to explore how online communities contribute to new forms of K-pop fandom. We suggest that these online sites play an important role in setting the new stage of dissemination and dialogue of K-pop knowledge, through which particular forms and spaces of online fan culture are being created and sustained. Moreover, these web-based communities challenge the existing concepts that have embraced interrelations between culture, consumption and technology. Based on an empirical study of YouTube, carried out using netnographic methods, this study tackles the following questions: how fans construct themselves as Korean pop fans through the online activities; how they exchange information and opinions of Korean stars; and, what meaning they extract from online file-sharing activities.

New Approach to MAC Protocol for Multiple AUV (수중 Multiple AUV를 위한 MAC 프로토콜 설계)

  • Cho, A-Ra;Park, Jong-Won;Kim, Seung-Geun;Choi, Young-Chol;Lim, Yong-Kon
    • Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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    • 2007.06a
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    • pp.213-216
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    • 2007
  • The paper deals with a approach to underwater acoustic based Ad-hoc communication, which allows major design strategies for Media Access Control (MAC) within a group of the autonomous underwater vehicles(AUV). The proposed MAC aims at deploying AUV-centric star topology, which minimizes overhead of sensor nodes and improves energy-efficiency. Furthermore, that is also well under long and unknown propagation delays of the underwater acoustic medium. The implemented MAC protocol makes it easier to achieve frame synchronization than TDMA due to deploying localized schedule time, in addition to saving energy consumption by letting nodes sleep. It is also superior to MACA and MACAW in terms of propagation delay. This scalable centralized protocol has the potential to serve as a primer for development of MAC protocol for future underwater acoustic based ad-hoc networks.

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Tasks and Development plan of R.O.K. Navy to support Korean government's 『Indo-Pacific Strategy』 (한국의 『인도-태평양 전략』 지원을 위한 해군의 역할·발전방안 고찰)

  • Ji, Young
    • Maritime Security
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    • v.6 no.1
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    • pp.83-107
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    • 2023
  • To Republic of Korea in the Indo-Pacific region, the stability and prosperity of the area are directly coupled with national survival, interest. Currently, on account of strategic competition between U.S.A, and China in this area as well as supranational·non-conventional threats, the security environment is unstable, required joint/allied responses. So, lots of states inside(U.S.A., Japan, ASEAN, etc.), also, out of this Indo-Pacific area like EU-NATO, open their own strategy related in Indo-Pacific issues to be involved. R.O.K. government took its own line with publishing self strategy following this international trend, it can be shown korean government's strong intend to join in the pending security issues in this region with 'strategic clarity'. Now, R.O.K. Navy has to back up governments, policy. First, R.O.K. Navy should strengthen the relationship inside and take part in the multilateral cooperation of security. Second, to convey this deterrence message to potential threats, Navy is required to show of forces and have combined exercises. Also, as naval forces of advanced countries, Korea, Navy should be taken action in non-traditional threats, and help developing states improve their sea power. To fulfill this tasks in the wide ocean area, Navy need five inherent characteristics(mobility, flexibility, sustainability, capability of presence and projection). In the end, this paper propose the development plan following operational environment (SWOT) analysis as well.

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SEAMCAT Based Interference Evaluation Tool with 3D Terrain Display (3차원 지형 디스플레이 기능을 갖는 SEAMCAT 기반 전파 간섭 평가 도구)

  • Park, Sang Joon;Jeon, Jun Young;Lim, Chang Heon
    • Journal of the Institute of Electronics and Information Engineers
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    • v.50 no.10
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    • pp.13-20
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    • 2013
  • Currently, SEAMCAT has been widely used as a tool to evaluate the effects of interference among wireless communication systems. In the previous work, we have incorporated the ITU-R P.526 pathloss model to the existing SEAMCAT in order to support the capability of interference evaluation taking into account any specific terrain characteristics. Along with this, we have implemented a terrain display function based on the Google map. However, the two-dimensional Google map based display is not effective in helping users to figure out some terrain features including the elevation variation in a given region. In order to alleviate this difficulty, we have incorporated the three-dimensional terrain display using the API of the Google earth to the existing SEAMCAT and provided the capability of viewing the positions of the associated communication systems, the variation of the carrier intensity and interference intensity in location, shadow region indication, and line-of-sight analysis and presented an example of interference evaluation.

A Study on the Agent Based Infection Prediction Model Using Space Big Data -focusing on MERS-CoV incident in Seoul- (공간 빅데이터를 활용한 행위자 기반 전염병 확산 예측 모형 구축에 관한 연구 -서울특별시 메르스 사태를 중심으로-)

  • JEON, Sang-Eun;SHIN, Dong-Bin
    • Journal of the Korean Association of Geographic Information Studies
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    • v.21 no.2
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    • pp.94-106
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    • 2018
  • The epidemiological model is useful for creating simulation and associated preventive measures for disease spread, and provides a detailed understanding of the spread of disease space through contact with individuals. In this study, propose an agent-based spatial model(ABM) integrated with spatial big data to simulate the spread of MERS-CoV infections in real time as a result of the interaction between individuals in space. The model described direct contact between individuals and hospitals, taking into account three factors : population, time, and space. The dynamic relationship of the population was based on the MERS-CoV case in Seoul Metropolitan Government in 2015. The model was used to predict the occurrence of MERS, compare the actual spread of MERS with the results of this model by time series, and verify the validity of the model by applying various scenarios. Testing various preventive measures using the measures proposed to select a quarantine strategy in the event of MERS-CoV outbreaks is expected to play an important role in controlling the spread of MERS-CoV.

Implementation of integrated monitoring system for trace and path prediction of infectious disease (전염병의 경로 추적 및 예측을 위한 통합 정보 시스템 구현)

  • Kim, Eungyeong;Lee, Seok;Byun, Young Tae;Lee, Hyuk-Jae;Lee, Taikjin
    • Journal of Internet Computing and Services
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    • v.14 no.5
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    • pp.69-76
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    • 2013
  • The incidence of globally infectious and pathogenic diseases such as H1N1 (swine flu) and Avian Influenza (AI) has recently increased. An infectious disease is a pathogen-caused disease, which can be passed from the infected person to the susceptible host. Pathogens of infectious diseases, which are bacillus, spirochaeta, rickettsia, virus, fungus, and parasite, etc., cause various symptoms such as respiratory disease, gastrointestinal disease, liver disease, and acute febrile illness. They can be spread through various means such as food, water, insect, breathing and contact with other persons. Recently, most countries around the world use a mathematical model to predict and prepare for the spread of infectious diseases. In a modern society, however, infectious diseases are spread in a fast and complicated manner because of rapid development of transportation (both ground and underground). Therefore, we do not have enough time to predict the fast spreading and complicated infectious diseases. Therefore, new system, which can prevent the spread of infectious diseases by predicting its pathway, needs to be developed. In this study, to solve this kind of problem, an integrated monitoring system, which can track and predict the pathway of infectious diseases for its realtime monitoring and control, is developed. This system is implemented based on the conventional mathematical model called by 'Susceptible-Infectious-Recovered (SIR) Model.' The proposed model has characteristics that both inter- and intra-city modes of transportation to express interpersonal contact (i.e., migration flow) are considered. They include the means of transportation such as bus, train, car and airplane. Also, modified real data according to the geographical characteristics of Korea are employed to reflect realistic circumstances of possible disease spreading in Korea. We can predict where and when vaccination needs to be performed by parameters control in this model. The simulation includes several assumptions and scenarios. Using the data of Statistics Korea, five major cities, which are assumed to have the most population migration have been chosen; Seoul, Incheon (Incheon International Airport), Gangneung, Pyeongchang and Wonju. It was assumed that the cities were connected in one network, and infectious disease was spread through denoted transportation methods only. In terms of traffic volume, daily traffic volume was obtained from Korean Statistical Information Service (KOSIS). In addition, the population of each city was acquired from Statistics Korea. Moreover, data on H1N1 (swine flu) were provided by Korea Centers for Disease Control and Prevention, and air transport statistics were obtained from Aeronautical Information Portal System. As mentioned above, daily traffic volume, population statistics, H1N1 (swine flu) and air transport statistics data have been adjusted in consideration of the current conditions in Korea and several realistic assumptions and scenarios. Three scenarios (occurrence of H1N1 in Incheon International Airport, not-vaccinated in all cities and vaccinated in Seoul and Pyeongchang respectively) were simulated, and the number of days taken for the number of the infected to reach its peak and proportion of Infectious (I) were compared. According to the simulation, the number of days was the fastest in Seoul with 37 days and the slowest in Pyeongchang with 43 days when vaccination was not considered. In terms of the proportion of I, Seoul was the highest while Pyeongchang was the lowest. When they were vaccinated in Seoul, the number of days taken for the number of the infected to reach at its peak was the fastest in Seoul with 37 days and the slowest in Pyeongchang with 43 days. In terms of the proportion of I, Gangneung was the highest while Pyeongchang was the lowest. When they were vaccinated in Pyeongchang, the number of days was the fastest in Seoul with 37 days and the slowest in Pyeongchang with 43 days. In terms of the proportion of I, Gangneung was the highest while Pyeongchang was the lowest. Based on the results above, it has been confirmed that H1N1, upon the first occurrence, is proportionally spread by the traffic volume in each city. Because the infection pathway is different by the traffic volume in each city, therefore, it is possible to come up with a preventive measurement against infectious disease by tracking and predicting its pathway through the analysis of traffic volume.

An epidemiologic study on the seropositive rate of hepatitis A virus among a selected group of children and adults in Busan (부산지역 소아 및 성인의 A형 간염 바이러스 항체 양성률에 대한 역학적 조사)

  • Kwon, Young Ok;Choi, Im Jeong;Jung, Jin Wha;Park, Ji Hyun
    • Clinical and Experimental Pediatrics
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    • v.50 no.3
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    • pp.262-267
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    • 2007
  • Purpose : The prevalence of hepatitis A virus (HAV) in a certain community reflects that community's living standards and hygienic conditions. And the pattern of HAV infection differs over time and geography. Recently, a shift in prevalence has been observed in cases from chilhood to adulthood. We studied the HAV antibody prevalence in the general population in Busan. Methods : From October 2004 to March 2005, total 472 subjects were tested for HAV antibodies. All samples were collected from patients in Maryknol Hospital. Results : The overall seropositive rate was 22.8% (108/472). The seropositive rates were 1.7% in subjects aged 2-5 years, 1.7% in 6-10 years, 0% in 11-20 years, 40.5% in 21-30 years, 82.1% in 31-40 years, 94.7% in 41-50 years, and 100% in subjects aged over 50 years. There was no significant gap between gender groups. Conclusion : As the socioeconomic conditions in Korea have improved, the HAV seropositive rate in school-aged children has dramatically decreased in the last 20 years. But, the seropositive rate of HAV didn't differ according to gender. The seropositive rate of HAV in the pediatric group was very low, which suggests the increasing possibility of clinical HAV infection in adults in the near future. Therefore, we should actively prevent the spread of hepatits A virus. In order to do that, we need to reorganize our lifestyle and personel hygiene and carry out active and passive immunization to high risk groups.