• Title, Summary, Keyword: 해빙시스템

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Quality Consistence Analysis of Satellite-based Sea Ice Concentration Products (위성기반 해빙 농도 산출물들의 품질 일관성 분석)

  • Lee, Eunkyung;Seo, Minji;Lee, Kyeong-sang;Choi, Sungwon;Lee, Darae;Jin, Donghyun;Kwon, Chaeyoung;Kim, Honghee;Huh, Morang;Han, Kyung-Soo
    • Korean Journal of Remote Sensing
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    • v.33 no.3
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    • pp.333-338
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    • 2017
  • We compared sea ice concentration(SIC) and sea ice extent(SIE) using EUMETSAT Ocean and Sea Ice Satellite Application Facilities(OSI SAF) and NASA Team(NT) sea ice algorithm in the Arctic during 1980-2010 to investigate the difference between sea ice data applied different algorithms. SIC and SIE of the two data showed different consistency by season and by sea area. Seasonally, SIC of OSI SAF was 0.85 % overall, 0.48 % in spring, 0.97 % in summer, 1.38 % in autumn and 0.66 % in winter higher than NT SIC. By sea area, OSI SAF SIC was 2.7 %, SIE was $198,000km^2$ higher than NT in Arctic Ocean, but in Lincoln Sea, OSI SAF SIC was 2.3 %, SIE was $20,000km^2$ lower than NT.

Analyzing the Characteristics of Sea Ice Initial Conditions for a Global Ocean and Sea Ice Prediction System, the NEMO-CICE/NEMOVAR over the Arctic Region (전지구 해양·해빙예측시스템 NEMO-CICE/NEMOVAR의 북극 영역 해빙초기조건 특성 분석)

  • Ahn, Joong-Bae;Lee, Su-Bong
    • Journal of the Korean earth science society
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    • v.36 no.1
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    • pp.82-89
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    • 2015
  • In this study, the characteristics of sea ice initial conditions generated from a global ocean and sea ice prediction system, the Nucleus for European Modeling of the Ocean (NEMO) - Los Alamos Sea Ice Model (CICE)/NEMOVAR were analyzed for the period June 2013 to May 2014 over the Arctic region. For the purpose, the observed and reanalyzed data were used to compare with the sea ice initial conditions. Results indicated that the variability of the monthly sea ice extent and thickness in model initial conditions were well represented as compared to the observation, while it was found that the extent and thickness of Arctic sea ice in initial data were narrower and thinner than those in reanalysis and observation for the period. The reason for the narrower sea ice extent in model initial conditions seems to be due to the fact that the initial sea ice concentration at the boundary area of sea ice was about 20 percent less than the reanalysis data. Also, the reason for the thinner sea-ice thickness in the Arctic region is due to the underestimation of Arctic sea ice thickness (about 60 cm) of the model initial conditions in the Arctic Ocean area adjacent to Greenland and Arctic archipelago where thick sea ice appears all the year round.

A Study on Temperature Variation of Contact Wire by De-icing System (해빙시스템에 의한 전차선의 온도변화에 관한 연구)

  • Ahn, Byeong-Lib;Lee, Joo
    • Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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    • v.22 no.9
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    • pp.69-74
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    • 2008
  • The frost and freezing on contact wire in winter is a very serious problem Shocks at the mechanical interface of the collecting strips of the pantograph and the contact wire. Extra electrical resistance, which may affect quality of current collection at the contact wire / collecting strips of pantograph interface. De-icing system is to melt frost or freezing in contact wire. The principle of do-icing system is to melt frost or ice by Joule heat of contact wire impedance. The temperature of the contact wire was increased with increasing the current. But temperature of contact wire was decreased with increasing the velocity of the wind.

Sea Ice Detection using Microwave Remote Sensing Techniques in the Weddell Sea, Antarctica (마이크로웨이브 원격탐사를 이용한 남극 웨델해 해빙 관측)

  • 황종선;이방용;심재설;홍성민;윤호일;권태영;민경덕;김정우
    • Economic and Environmental Geology
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    • v.36 no.2
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    • pp.141-148
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    • 2003
  • We investigated the distribution of sea ice using various microwave remote sensing techniques including radar altimeter, radiometer, and scatterometer data in the part of Drake passage, Antarctica, between the area 45$^{\circ}$-75$^{\circ}$W and 55$^{\circ}$-66$^{\circ}$S. Topex/poseidon radar altimeter data were used to analyze the monthly distribution of sea ice surface area between 1992 and 1999 by using Geo_bad_1 flag or MGDR. From satellite radiometer measurements of DMSP's SSM/I, sea ice concentration was extracted during the period from 1993 to 1996. To select a value of ice concentration, normally ranging from 0 to 100%, that can be used as a critical value of judging the existence for ice, sea ice areas estimated from various ice concentrations of radiometer measurements were correlated with the area estimated from the radar altimeter measurements. As a result, 20% of ice concentration was selected, and, then this value was used to integrate radiometer data with radar altimeter and ERS-1/2 scatterometer data. To indirectly verify the result, the last 20 year's sea ice concentration was correlated with surface temperature data near Esper-anza Observation Station. The two data showed a high correlation coefficient of 0.86. The amount of sea ice and temperature variation were found to be closely related in the study area, and this indirectly verifies the result of this study. We provided a method to judge the existence of sea ice from ice concentration of satellite radiometer data and suggested a method to monitor more detailed temporal and spatial variation of sea ice distribution by integra-tion of various microwave remote sensing techniques.

A Study on Deicing Current Estimation Technique and Configuration Process for Deicing System in the Conventional Line (기존선 해빙시스템을 위한 해빙전류 예측기법 및 구성 절차에 관한 연구)

  • Kwon, Sam-Young;Park, Young;Jung, Ho-Sung
    • Journal of the Korean Society for Railway
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    • v.9 no.2
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    • pp.237-243
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    • 2006
  • Deicing system is to melt frost or ice freezed in catenary line when the temperature is lower than $0^{\circ}C$ in winter. The principle of deicing system is to melt frost or ice by Joule heat of catenary impedance. The performance of deicing is dependant of deicing current determined by the length of deicing section, deicing impedance and current division ratio of catenary line and messenger line. So, we present technique for estimating deicing current and process for determination of deicing section in the conventional line. Deicing impedance is estimated using Carson-Pollaczek equation, and current division ratio of catenary line and messenger line is estimated using voltage drop, and deicing current is estimated using power system data of deicing system. For the determination of the final deicing section, we verified estimated value comparing with experiment value of deicing impedance and current division ratio of catenary line and messenger line using low voltage experiment. Finally, we verified the validity of estimation technique and process using a simulated test data of real deicing system operation in the Chungju Substation, Chungbuk line.

Numerical Study on the Role of Sea-ice Using Ocean General Circulation Model (해양대순환모형을 이용한 해빙의 역할에 관한 수치실험 연구)

  • Lee, Jin-Ah;Ahn, Joong-Bae
    • The Sea
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    • v.6 no.4
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    • pp.225-233
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    • 2001
  • In order to find out the role of sea-ice in the climate system, a thermodynamic sea-ice model has been developed and included in the ocean general circulation model, MOM2, for the construction of OGCM/sea-ice coupled model in this study. By using the model developed, seasonal mean sea-ice distribution has been simulated, first of all. The role of sea-ice in the sense of large scale ocean circulation has been studied by comparing the results of OGCM/sea-ice coupled model experiment with OGCM-standalone experiment. At the same time, the coupled model has been verified by comparing and analysing the results of the other models and observation. The coupled model has reasonably simulated the overall seasonal distribution of sea-ice in the high latitudes of both hemispheres. In the comparative analysis between the OGCM/sea-ice coupled and OGCM-standalone experiments, the sea-ice is playing important roles on maintaining not only the distributions of temperature and salinity in high latitudes of both hemispheres, but also the meridional ocean circulation associated with south ocean cell, southern hemisphere cell and zonal ocean circulation such as a circum-polar current.

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Downscaling of AMSR2 Sea Ice Concentration Using a Weighting Scheme Derived from MODIS Sea Ice Cover Product (MODIS 해빙피복 기반의 가중치체계를 이용한 AMSR2 해빙면적비의 다운스케일링)

  • Ahn, Jihye;Hong, Sungwook;Cho, Jaeil;Lee, Yang-Won
    • Korean Journal of Remote Sensing
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    • v.30 no.5
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    • pp.687-701
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    • 2014
  • Sea ice is generally accepted as an important factor to understand the process of earth climate changes and is the basis of earth system models for analysis and prediction of the climate changes. To continuously monitor sea ice changes at kilometer scale, it is demanded to create more accurate grid data from the current, limited sea ice data. In this paper we described a downscaling method for Advanced Microwave Scanning Radiometer 2 (AMSR2) Sea Ice Concentration (SIC) from 10 km to 1 km resolution using a weighting scheme of sea ice days ratio derived from Moderate Resolution Imaging Spectroradiometer (MODIS) sea ice cover product that has a high correlation with the SIC. In a case study for Okhotsk Sea, the sea ice areas of both data (before and after downscaling) were identical, and the monthly means and standard deviations of SIC exhibited almost the same values. Also, Empirical Orthogonal Function (EOF) analyses showed that three kinds of SIC data (ERA-Interim, original AMSR2, and downscaled AMSR2) had very similar principal components for spatial and temporal variations. Our method can apply to downscaling of other continuous variables in the form of ratio such as percentage and can contribute to monitoring small-scale changes of sea ice by providing finer SIC data.

Classification for landfast sea ice types in Greenland with texture analysis images (텍스쳐 이미지를 이용한 그린란드 정착빙의 분류)

  • Hwang, Do-Hyun;Hwang, Byong-Jun;Yoon, Hong-Joo
    • The Journal of the Korea institute of electronic communication sciences
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    • v.8 no.4
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    • pp.589-593
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    • 2013
  • Remote sensing of SAR images is suitable for sea ice observations to obtain the sea ice data if clouds or weather conditions change. There are various types of sea ice, classification results can be seen more easily to detect the change by types of sea ice. In this study, we classified the image by supervised classification method, which is minimum distance was used. Also, we compared the overall accuracy when compared to the results with classification result of SAR images and the result of texture images. When using Radarsat-2 texture images, the overall accuracy was the highest, generally, when using the SAR images had higher overall accuracy.

Design of Portable Measuring Devices Used for Field Ice Experiments (극지 해양플랜트 현장시험용 해빙의 재료특성 간이 계측장비 개발)

  • Choi, Kyung-Sik;Kim, Jung-Hyun;Kim, Jeong-Seon;Ha, Jung-Seok
    • Proceedings of the Computational Structural Engineering Institute Conference
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    • pp.126-131
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    • 2010
  • 본 논문에서는 극지 빙해역을 운항하는 쇄빙선박이나 해양구조물에 작용하는 해빙의 재료특성을 계측할 수 있는 간이 실험 장비를 제작하였다. 극지 빙해역을 운항하는 쇄빙선박의 빙저항이나 해양구조물에 작용하는 빙하중을 추정하기 위해서 극지 현장에서 실규모의 시험을 수행하게 되는데, 저온과 얼음이라는 악조건을 극복하기 위한 빙역학 기술과 특수 장비가 필요하다. 국내에 한국해양연구원 MOERI 빙해수조가 완공됨에 따라 얼음의 특성을 고려한 모형빙 재료특성 시험용 계측장비가 일부 마련이 되었으나 빙해역 현장 시험에 대한 경험이 전무하며, 계측장비에 대한 지식과 기술 역시 확보되지 못한 실정이다. 본 연구에서는 차후 쇄빙연구선 ARAON호를 이용한 빙해역의 실선계측 시 해빙의 강도를 측정하기 위한 계측시스템 마련의 일환으로 시험편 획득을 위한 코어링 장비와, 해빙의 재료특성 중 1축 압축강도를 측정하기 위한 간이 압축시험기 그리고 얼음의 결정구조를 파악하기 위한 편광기를 제작하였다. 또한 극지 현장실험에 적용할 실험기법 확보를 위한 일련의 과정을 마련하기 위해 제작된 장비를 이용해 소양호에서 현장실험을 수행하였고 계측된 결과를 참고문헌과 비교해본 결과 유사한 값을 갖는 것을 확인할 수 있었다.

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Determination of dynamic threshold for sea-ice detection through relationship between 11 µm brightness temperature and 11-12 µm brightness temperature difference (11 µm 휘도온도와 11-12 µm 휘도온도차의 상관성 분석을 활용한 해빙탐지 동적임계치 결정)

  • Jin, Donghyun;Lee, Kyeong-Sang;Choi, Sungwon;Seo, Minji;Lee, Darae;Kwon, Chaeyoung;Kim, Honghee;Lee, Eunkyung;Han, Kyung-Soo
    • Korean Journal of Remote Sensing
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    • v.33 no.2
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    • pp.243-248
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    • 2017
  • Sea ice which is an important component of the global climate system is being actively detected by satellite because it have been distributed to polar and high-latitude region. and the sea ice detection method using satellite uses reflectance and temperature data. the sea ice detection method of Moderate-Resolution Imaging Spectroradiometer (MODIS), which is a technique utilizing Ice Surface Temperature (IST) have been utilized by many studies. In this study, we propose a simple and effective method of sea ice detection using the dynamic threshold technique with no IST calculation process. In order to specify the dynamic threshold, pixels with freezing point of MODIS IST of 273.0 K or less were extracted. For the extracted pixels, we analyzed the relationship between MODIS IST, MODIS $11{\mu}m$ channel brightness temperature($T_{11{\mu}m}$) and Brightness Temperature Difference ($BTD:T_{11{\mu}m}-T_{12{\mu}m}$). As a result of the analysis, the relationship between the three values showed a linear characteristic and the threshold value was designated by using this. In the case ofsea ice detection, if $T_{11{\mu}m}$ is below the specified threshold value, it is detected as sea ice on clear sky. And in order to estimate the performance of the proposed sea ice detection method, the accuracy was analyzed using MODIS Sea ice extent and then validation accuracy was higher than 99% in Producer Accuracy (PA).