• ETRI Journal
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• 제7권4호
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• pp.3-10
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• 1985

비간섭성 LED 광원으로 부터의 빛이 다중모우드 광섬유를 약 10km이상 지났을 때 광의 입사조건에 무관하게 정상상태(Steady-state) 에 이르며, 정상상태의 광섬유 출사단의 near-field 광 파워 분포가 가우시안(Gaussian) 함수 형태임을 알 수 있었다. 이 가우시안 함수형태의 정상상태에서 측정된 광섬유의 손실은 매우 안정된 측정치를 나타내었다. 한편 가간섭성 LD광원을 사용할 경우 10km까지 near-field광 파워 분포에서 스페클(Speckle) 현상을 볼 수 있었고, LD의 간섭성과 발광 모우드 형태의 불균일로 인하여 20km 이상까지 LED에서와 같은 정상상태에 이르지 않고 있었으나 이 상태에서 측정된 광섬유의 손실치는 비교적 안정하였다.

• Journal of Astronomy and Space Sciences
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• 제33권3호
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• pp.197-205
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• 2016

We investigated two flares in the solar atmosphere that occurred on June 3, 2012 and July 6, 2012 and caused propagation of Moreton and EIT waves. In the June 3 event, we noticed a filament winking which presumably was caused by the wave propagation from the flare. An interesting feature of this event is that there was a reflection of this wave by a coronal hole located alongside the wave propagation, but not all of this wave was transmitted by the coronal hole. Using the running difference method, we calculated the speed of Moreton and EIT waves and we found values of 926 km/s before the reflection and 276 km/s after the reflection (Moreton wave) and 1,127 km/s before the reflection and 46 km/s after the reflection (EIT wave). In the July 6 event, this phenomenon was accompanied by type II and type III solar radio bursts, and we also performed a running difference analysis to find the speed of the Moreton wave, obtaining a value of 988 km/s. The speed derived from the analysis of the solar radio burst was 1,200 km/s, and we assume that this difference was caused by the different nature of the motions in these phenomena, where the solar radio burst was caused by the propagating particles, not waves.

• Proceedings of the National Institute of Ecology of the Republic of Korea
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• 제2권4호
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• pp.285-292
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• 2021

We investigated habitat use and home range of a rescued and released white-naped crane using GPS tracking technology in Cheorwon, South Korea, from October 2016 to March 2017. Four types of roosting sites were identified: frozen reservoirs, paddy fields, rivers, and wetlands. Upon arrival, the white-naped crane preferred wetlands in the Demilitarized Zone (DMZ). In late wintering season, it showed a tendency to change main roosting sites in the following order: rice paddies, rivers, and frozen reservoirs. Among 14 sleeping places, Civilian Control Zone (CCZ) with various type of available habitats was more preferred than the DMZ. Places outside of CCZ were rarely used due to anthropogenic disturbances during the night. The tracked white-naped crane widely chose daytime feeding sites while moving around all over rice paddies in the CCZ. Mean diurnal movement distance was 10.5 km with a maximum of 24.8 km. Its home range measured with Minimum Convex Polygon (MCP) and Kernel Density Estimation (KDE) was 172.30 km² with MCP, 159.60 km² with KDE 95%, 132.48 km² with KDE 90%, and 42.45 km² with KDE 50%. All estimated values of home ranges were higher in the early and later winter than those in the middle period.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2009년도 춘계학술대회 논문집 특별세미나,특별/일반세션
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• pp.201-206
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• 2009

In the testing stage of HEMU-400X(next Korean high speed train) developing project, maximum speed(400km/h) tests will be conducted. On present and near future conditions of the overhead contact lines, 400km/h is over the design speed criteria. The predictions of current collection performance including the percentage loss of contact(arcs level) parameter through dynamic interaction simulation of HEMU-400X maximum speed test run are described in this paper. Various simulations are conducted at the condition of two different contact wire tensions to draw the proper contact wire increasing values in the 400km/h test line under the available contact wire tension supporting condition of that line.

• Asia pacific journal of information systems
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• 제32권1호
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• pp.151-167
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• 2022

This paper is motivated by social influence theory implying the multilevel nature of knowledge management (KM) in an organization. Organizational knowledge is generated and distributed by individuals from different groups across organizational boundaries. Its transfers are supported by IS/IT practice, i.e., the individual and collective use of the technology available in the organization. I propose a multilevel perspective to explain how IS/IT practice supports multilevel KM capabilities to manage organizational knowledge successfully and how the effectiveness of multilevel KM capabilities expands into the improvement of multilevel task-related organizational performance. The multilevel KM theory extends the knowledge-based view of the firm by describing the dynamic process through which strategic values of knowledge are generated by IS/IT practice across the organizational levels. This paper also discusses multilevel insights on the strategic value of organizational learning based on the social context of organizations.

• 농촌계획
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• 제9권1호
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• pp.65-75
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• 2003

As a pre-step research to make land-use planning in the region level, this study aims to analyze some probability pattern representing transition probabilities from farmland to others using the sequential detailed digital land-use maps. Kinki and Chubu regions of Japan, which have Osaka and Nagoya cities as their center places respectively, were selected as test regions in this study. The 10m grid land-use maps for four time series at every 5 year from 1977 to 1992 were used. In this study, the regions were divided into three sub-areas 10km, 20km, and 30km according to distance from center cities, respectively. The correlation coefficient (CC) between sub-areas with same distance in the two regions was calculated to analyze whether or not the two regions have common points in the pattern of land-use conversion probability from farmland to other types. The probability distribution of the converted areas which were moved to the urbanized area (residential, commercial, industrial, road, park and public facility areas) was about $40{\sim}70%$ for both all periods and sub-areas. According to distance from city centers, the probability moved to the urbanized area was about 60% at 10km area, and 40% at the 30km area, which means that the values we decreased gradually, while in the case moved to the forest and the etc areas, the values were increased slightly. The CC analysis from the paddy field and the dry field to the others separately showed that there is high correlation in the probability pattern between the two regions.

• 한국산학기술학회논문지
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• 제14권7호
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• pp.3518-3527
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• 2013

새로 개발된 차세대고속열차(HEMU-430X)가 400km/h 이상의 고속운행을 앞두고 있으나, 우리나라 철도설계기준은 350km/h이하의 운행속도에 대한 지침을 제시하고 있으며, 호남고속선도 350km/h이하의 기준을 적용하여 설계되었다. 350km/h를 초과하는 고속운행에 대해 기존 인프라의 성능을 검토하고, 고속운행을 대비한 설계기준 마련이 시급한 바, 이 연구에서는 증속에 대한 경부선 가야고가에 대해 시뮬레이션하고, 차세대고속열차(HEMU-430X) 시험운행 중 측정된 가야고가의 가속도, 변위 데이터를 비교, 검토하여 350km/h이상의 열차운행에 대한 강합성 소수주형교의 동적거동을 분석하였다. 경부고속선 가야고가 분석결과를 토대로 내년도 완공을 앞두고 있는 호남고속선 연정교에 대해 수치해석을 통해 실제 HEMU 시범운행시 발생할 수 있는 동적 거동을 예측하였다.

• Journal of information and communication convergence engineering
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• 제5권2호
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• pp.164-170
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• 2007

In this paper, the new method alternating with the method for forming the symmetrical distribution of power and local dispersion in high bit-rate WDM system with optical phase conjugator (OPC) is proposed. The proposed method is carried by finding out the optimal values of OPC position offset and fiber dispersion offset. It is assumed to be that NRZ-formatted 24-channels of 40 Gbps are simultaneously propagated in WDM system with non zero - dispersion shifted fiber (NZ-DSF) of 1,000 km. It is confirmed that the compensation extents of overall WDM channels are more improved by applying the induced optimal values into WDM system than those in WDM system with the conventional mid-span spectral inversion (MSSI) technique, and the searching procedure of the optimal values makes little difference of performance if the optimal value of one parameter related with another parameter. And, it is confirmed that the flexible design of WDM system with OPC is possible by effectiviely using by these optimal values. Thus, it is expected that the proposed method alternate with the forming method of the symmetrical distributions of power and local dispersion.

• 한국지구물리탐사학회:학술대회논문집
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• 한국지구물리탐사학회 2008년도 공동학술대회
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• pp.97-100
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• 2008

일본 후지산은 역사적, 지질학적, 그리고 최근의 지진학적 징후로부터 화산활동의 재개에 의한 재해가능성이 있어 화산감시연구가 집중되고 있다. 후지산 감시활동의 일환으로 축적된 방대한 주변지역 지진자료를 바탕으로 단일산란모델에 의한 코다감쇠상수($Q_c^{-1}$)와 다중시간창분석에 의한 고유 및 산란감쇠상수 ($Q_i^{-1}$, $Q_s^{-1}$)를 측정하였다. 본 연구는 후지산 아래에 존재하는 것으로 여겨지고 있는 용암체의 감쇠구조에 초점을 맞추기 위해 정상에서 반경 5km 이내의 지대를 지진파가 통과하는 '후지산 근방', 지진파 통과지역이 모두 반경 20 km 바깥인 '먼 후지산'으로 자료를 분류하였다. 본 연구는 자료가 풍부하여 비교적 작은 오차범위를 나타내고 있는데, '후지산 근방'의 모든 감쇠상수 수 $Q^{-1}$는 '먼 후지산'에 비해 컸으며, 두 지대 공히 고주파 영역에서의 $Q_i^{-1}$값은 $Q_s^{-1}$ 값에 비해 높은 값이었다. 그러나, '후지산 근방'의 $Q_i^{-1}$ 값은 다른 화산지역에 비해 낮았는데, 이는 하와이화산과 같은 활동적인 화산에 비해 용융도의 비율이 낮거나 마그마활동이 덜한 것으로 해석된다.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2010년도 춘계학술대회 논문집
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• pp.984-988
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• 2010

In Korea, the next generation high-speed train, whose target is maximum speed of 400km/h and operating speed of 370km/h, has been developed since 2007. In this paper, the safety of the next generation high-speed train is compared UIC 518OR under the malfunctioning situation of the suspension system. The bogie of the next generation high-speed train has two suspensions. Two different vehicle models of the next generation high-speed train are created by using VAMPIRE and ADAMS/Rail, which are specialized to design railway vehicle. And Those models are showed same dynamic properties. First of all, the sensitivity analysis of ModelCenter is performed using model of VAMPIRE. One suspension element which has significant effects on the safety are selected by result of the sensitivity analysis. And then, the dynamic analysis when the suspension element is broken is performed using ADAMS/Rail. The 30km track between Pungsegyo and Biryong tunnel in Gyeongbu High-speed Line was used at the dynamic analysis. The estimated value is found by using the normal method of UIC 518OR. The estimated values on the normal/fault state and the limit values of UIC 518OR are compared. Finally, the safety of the next generation high-speed train is verified.