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A Method of Feature Extraction on Motor Imagery EEG Using FLD and PCA Based on Sub-Band CSP (서브 밴드 CSP기반 FLD 및 PCA를 이용한 동작 상상 EEG 특징 추출 방법 연구)

  • Park, Sang-Hoon;Lee, Sang-Goog
    • Journal of KIISE
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    • v.42 no.12
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    • pp.1535-1543
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    • 2015
  • The brain-computer interface obtains a user's electroencephalogram as a replacement communication unit for the disabled such that the user is able to control machines by simply thinking instead of using hands or feet. In this paper, we propose a feature extraction method based on a non-selected filter by SBCSP to classify motor imagery EEG. First, we divide frequencies (4~40 Hz) into 4-Hz units and apply CSP to each Unit. Second, we obtain the FLD score vector by combining FLD results. Finally, the FLD score vector is projected onto the optimal plane for classification using PCA. We use BCI Competition III dataset IVa, and Extracted features are used as input for LS-SVM. The classification accuracy of the proposed method was evaluated using $10{\times}10$ fold cross-validation. For subjects 'aa', 'al', 'av', 'aw', and 'ay', results were $85.29{\pm}0.93%$, $95.43{\pm}0.57%$, $72.57{\pm}2.37%$, $91.82{\pm}1.38%$, and $93.50{\pm}0.69%$, respectively.

Climate Change Impact Analysis of Urban Inundation in Seoul Using High-Resolution Climate Change Scenario (고해상도 기후시나리오를 이용한 서울지역 배수시스템의 기후변화 영향 분석)

  • Lee, Moon-Hwan;Kim, Jae-Pyo;Bae, Deg-Hyo
    • Journal of Korea Water Resources Association
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    • v.48 no.5
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    • pp.345-355
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    • 2015
  • Climate change impact on urban drainage system are analyzed in Seoul by using high-resolution climate change scenario comparing 2000s (1971~2000) with 2020s (2011~2040), 2050s (2041~2070) and 2080s (2071~2100). The historical hourly observed rainfall data were collected from KMA and the climate change scenario-based hourly rainfall data were produced by RegCM3 and Sub-BATS scheme in this study. The spatial resolution obtained from dynamic downscaling was $5{\times}5km$. The comparison of probability rainfalls between 2000s and 2080s showed that the change rates are ranged on 28~54%. In particular, the increase rates of probability rainfall were significant on 3, 6 and 24-hour rain durations. XP-SWMM model was used for analyzing the climate change impacts on urban drainage system. As the result, due to the increase of rainfall intensities, the inundated areas as a function of number of flooded manhole and overflow amounts were increasing rapidly for the 3 future periods in the selected Gongneung 1, Seocho 2, Sinrim 4 drainage systems. It can be concluded that the current drainage systems on the selected study area are vulnerable to climate change and require some reasonable climate change adaptation strategies.

New Regional Geography in Korea : (2) Trends and Issues of Regional Research in Major Subfields (한국의 신지역지리학 : (2) 지리학 분야별 지역 연구 동향과 과제)

  • Choi, Byung-Doo
    • Journal of the Korean association of regional geographers
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    • v.22 no.1
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    • pp.1-24
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    • 2016
  • This paper is to consider trends and issues of regional research in major sub-fields of human geography in Korea, following the previous one which dealt with contexts and general trends of new regional geography in Korea since the 2000s. They include historical and cultural geography on place and landscape, economic geography on industrial districts or agglomerated regions (i.e. clusters) and urban (and social) geography on urban networks and differentiation. Even though researchers in sub-fields have used different terms and concepts to identify region, they are in common to relate specificities of region to general processes such as (de)modernization, (de)industrialization, and globalization, to understand region as social and discursive constitution as well as substantive reality, and to give more attention to socio-spatial networks and relationality than territoriality of regions. These common points seem to reflect the emerging trend of new regional geography, and to get rid of existing traditional concept of region. It is suggested that major tasks for conceptualization of region in future research are to overcome dichotomy of speciality and generality, of substantive reality and discursive constitution, and of territoriality and relationality, and that important issues for empirical research on region include regional synthesis from new perspectives, uneven regional development as relational process in and between regions, and producing practice for alternative regions.

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Numerical Simulation of Cavitating Flows on a Foil by Using Bubble Size Distribution Model

  • Ito, Yutaka;Nagasaki, Takao
    • Proceedings of the Korean Society of Propulsion Engineers Conference
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    • 2004.03a
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    • pp.216-227
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    • 2004
  • A new cavitating model by using bubble size distribution based on bubbles-mass has been proposed. Both liquid and vapor phases are treated with Eulerian framework as a mixture containing minute cavitating bubbles. In addition vapor phase consists of various sizes of vapor bubbles, which are distributed to classes based on their mass. The bubble number-density for each class was solved by considering the change of the bubble-mass due to phase change as well as generation of new bubbles due to heterogeneous nucleation. In this method, the bubble-mass is treated as an independent variable, and the other dependent variables are solved in spatial coordinates and bubble-mass coordinate. Firstly, we employed this method to calculate bubble nucleation and growth in stationary super-heated liquid nitrogen, and bubble collapse in stationary sub-cooled one. In the case of bubble growth in super-heated liquid, bubble number-density of the smallest class based on its mass is increased due to the nucleation. These new bubbles grow with time, and the bubbles shift to larger class. Therefore void fraction of each class is increased due to the growth in the whole class. On the other hand, in the case of bubble collapse in sub-cooled liquid, the existing bubbles are contracted, and then they shift to smaller class. It finally becomes extinct at the smallest one. Secondly, the present method is applied to a cavitating flow around NACA00l5 foil. Liquid nitrogen and liquid oxygen are employed as working fluids. Cavitation number, $\sigma$, is fixed at 0.15, inlet velocities are changed at 5, 10, 20 and 50m/s. Inlet temperatures are 90K in case of liquid nitrogen, and 90K and 1l0K in case of liquid oxygen. 110K of oxygen is corresponding to the 90K of nitrogen because of the same relative temperature to the critical one, $T_{r}$=$T/T_c^{+}$. Cavitating flow around the NACA0015 foils was properly analyzed by using bubble size distribution. Finally, the method is applied to a cavitating flow in an inducer of the LE-7A hydrogen turbo-pump. This inducer has 3 spiral foils. However, for simplicity, 2D calculation was carried out in an unrolled channel at 0.9R cross-section. The channel moves against the fluid at a peripheral velocity corresponding to the inducer revolutions. Total inlet pressure, $Pt_{in}$, is set at l00KPa, because cavitation is not generated at a design point, $Pt_{in}$=260KPa. The bubbles occur upstream of the foils and collapse between them. Cavitating flow in the inducer was successfully predicted by using the bubble size distribution.

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Analysis on the Performance Degradation of MIMO-OFDM Receiver and Hybrid Interference Cancellation with Low Complexity for the Performance Improvement Under High-Mobility Condition (MIMO-OFDM 수신기의 성능 열화 분석 및 고속 이동환경에서의 성능 향상을 위한 저복잡도 HIC 간섭제거 기법)

  • Kang, Seung-Won;Kim, Kyoo-Hyun;Chang, Kyung-Hi
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.32 no.2C
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    • pp.95-112
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    • 2007
  • Spatial Multiplexing techniques, which is a kind of Multiple antenna techniques, provide high data transmission rate by transmitting independent data at different transmit antenna with the same spectral resource. OFDM (Orthogonal Frequency Division Multiplexing) is applied to MIMO (Multiple-Input Multiple-Output) system to combat ISI (Inter-Symbol Interference) and frequency selective fading channel, which degrade MIMO system performance. But, orthogonality between subcarriers of OFDM can't be guaranteed under high-mobility condition. As a result, severe performance degradation due to ICI is induced. In this paper, both ICI and CAI (Co-Antenna Interference) which occurs due to correlation between multiple antennas, and performance degradation due to both ICI and CAI are analyzed. In addition to the proposed CIR (Channel Impulse Response) estimation method for avoiding loss in data transmission rate, HIC (Hybrid Interference Cancellation) approach for guaranteeing QoS of MIMO-OFDM receiver is proposed. We observe the results on analytical performance degradation due to both ICI & CAI are coincide with the simulation results and performance improvement due to HIC are also verified by simulation under SCM-E Sub-urban Macro MIMO channel.

Recent Technological Advances in Optical Instruments and Future Applications for in Situ Stable Isotope Analysis of CH4 in the Surface Ocean and Marine Atmosphere (표층해수 내 용존 메탄 탄소동위원소 실시간 측정을 위한 광학기기의 개발 및 활용 전망)

  • PARK, MI-KYUNG;PARK, SUNYOUNG
    • The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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    • v.23 no.1
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    • pp.32-48
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    • 2018
  • The mechanisms of $CH_4$ uptake into and release from the ocean are not well understood due mainly to complexity of the biogeochemical cycle and to lack of regional-scale and/or process-scale observations in the marine boundary layers. Without complete understanding of oceanic mechanisms to control the carbon balance and cycles on a various spatial and temporal scales, however, it is difficult to predict future perturbation of oceanic carbon levels and its influence on the global and regional climates. High frequency, high precision continuous measurements for carbon isotopic compositions from dissolved $CH_4$ in the surface ocean and marine atmosphere can provide additional information about the flux pathways and production/consumption processes occurring in the boundary of two large reservoirs. This paper introduces recent advances on optical instruments for real time $CH_4$ isotope analysis to diagnose potential applications for in situ, continuous measurements of carbon isotopic composition of dissolved $CH_4$. Commercially available, three laser absorption spectrometers - quantum cascade laser spectroscopy (QCLAS), off-axis integrated cavity output spectrometer (OA-ICOS), and cavity ring-down spectrometer (CRDS) are discussed in comparison with the conventional isotope ratio mass spectrometry (IRMS). Details of functioning and performance of a CRDS isotope instrument for atmospheric ${\delta}^{13}C-CH_4$ are also given, showing its capability to detect localized methane emission sources.

Land Cover Classification of the Korean Peninsula Using Linear Spectral Mixture Analysis of MODIS Multi-temporal Data (MODIS 다중시기 영상의 선형분광혼합화소분석을 이용한 한반도 토지피복분류도 구축)

  • Jeong, Seung-Gyu;Park, Chong-Hwa;Kim, Sang-Wook
    • Korean Journal of Remote Sensing
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    • v.22 no.6
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    • pp.553-563
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    • 2006
  • This study aims to produce land-cover maps of Korean peninsula using multi-temporal MODIS (Moderate Resolution Imaging Spectroradiometer) imagery. To solve the low spatial resolution of MODIS data and enhance classification accuracy, Linear Spectral Mixture Analysis (LSMA) was employed. LSMA allowed to determine the fraction of each surface type in a pixel and develop vegetation, soil and water fraction images. To eliminate clouds, MVC (Maximum Value Composite) was utilized for vegetation fraction and MinVC (Minimum Value Composite) for soil fraction image respectively. With these images, using ISODATA unsupervised classifier, southern part of Korean peninsula was classified to low and mid level land-cover classes. The results showed that vegetation and soil fraction images reflected phenological characteristics of Korean peninsula. Paddy fields and forest could be easily detected in spring and summer data of the entire peninsula and arable land in North Korea. Secondly, in low level land-cover classification, overall accuracy was 79.94% and Kappa value was 0.70. Classification accuracy of forest (88.12%) and paddy field (85.45%) was higher than that of barren land (60.71%) and grassland (57.14%). In midlevel classification, forest class was sub-divided into deciduous and conifers and field class was sub-divided into paddy and field classes. In mid level, overall accuracy was 82.02% and Kappa value was 0.6986. Classification accuracy of deciduous (86.96%) and paddy (85.38%) were higher than that of conifers (62.50%) and field (77.08%).

Detection of Wildfire Smoke Plumes Using GEMS Images and Machine Learning (GEMS 영상과 기계학습을 이용한 산불 연기 탐지)

  • Jeong, Yemin;Kim, Seoyeon;Kim, Seung-Yeon;Yu, Jeong-Ah;Lee, Dong-Won;Lee, Yangwon
    • Korean Journal of Remote Sensing
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    • v.38 no.5_3
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    • pp.967-977
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    • 2022
  • The occurrence and intensity of wildfires are increasing with climate change. Emissions from forest fire smoke are recognized as one of the major causes affecting air quality and the greenhouse effect. The use of satellite product and machine learning is essential for detection of forest fire smoke. Until now, research on forest fire smoke detection has had difficulties due to difficulties in cloud identification and vague standards of boundaries. The purpose of this study is to detect forest fire smoke using Level 1 and Level 2 data of Geostationary Environment Monitoring Spectrometer (GEMS), a Korean environmental satellite sensor, and machine learning. In March 2022, the forest fire in Gangwon-do was selected as a case. Smoke pixel classification modeling was performed by producing wildfire smoke label images and inputting GEMS Level 1 and Level 2 data to the random forest model. In the trained model, the importance of input variables is Aerosol Optical Depth (AOD), 380 nm and 340 nm radiance difference, Ultra-Violet Aerosol Index (UVAI), Visible Aerosol Index (VisAI), Single Scattering Albedo (SSA), formaldehyde (HCHO), nitrogen dioxide (NO2), 380 nm radiance, and 340 nm radiance were shown in that order. In addition, in the estimation of the forest fire smoke probability (0 ≤ p ≤ 1) for 2,704 pixels, Mean Bias Error (MBE) is -0.002, Mean Absolute Error (MAE) is 0.026, Root Mean Square Error (RMSE) is 0.087, and Correlation Coefficient (CC) showed an accuracy of 0.981.

Comparison of Model-simulated Atmospheric Carbon Dioxide with GOSAT Retrievals

  • Shim, Chang-Sub;Nassar, Ray;Kim, Jhoon
    • Asian Journal of Atmospheric Environment
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    • v.5 no.4
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    • pp.263-277
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    • 2011
  • Global atmospheric $CO_2$ distributions were simulated with a chemical transport model (GEOS-Chem) and compared with space-borne observations of $CO_2$ column density by GOSAT from April 2009 to January 2010. The GEOS-Chem model simulated 3-D global atmospheric $CO_2$ at $2^{\circ}{\times}2.5^{\circ}$ horizontal resolution using global $CO_2$ surface sources/sinks as well as 3-D emissions from aviation and the atmospheric oxidation of other carbon species. The seasonal cycle and spatial distribution of GEOS-Chem $CO_2$ columns were generally comparable with GOSAT columns over each continent with a systematic positive bias of ~1.0%. Data from the World Data Center for Greenhouse Gases (WDCGG) from twelve ground stations spanning $90^{\circ}S-82^{\circ}N$ were also compared with the modeled data for the period of 2004-2009 inclusive. The ground-based data show high correlations with the GEOS-Chem simulation ($0.66{\leq}R^2{\leq}0.99$) but the model data have a negative bias of ~1.0%, which is primarily due to the model initial conditions. Together these two comparisons can be used to infer that GOSAT $CO_2$ retrievals underestimate $CO_2$ column concentration by ~2.0%, as demonstrated in recent validation work using other methods. We further estimated individual source/sink contributions to the global atmospheric $CO_2$ budget and trends through 7 tagged $CO_2$ tracers (fossil fuels, ocean exchanges, biomass burning, biofuel burning, net terrestrial exchange, shipping, aviation, and CO oxidation) over 2004-2009. The global $CO_2$ trend over this period (2.1 ppmv/year) has been mainly driven by fossil fuel combustion and cement production (3.2 ppmv/year), reinforcing the fact that rigorous $CO_2$ reductions from human activities are necessary in order to stabilize atmospheric $CO_2$ levels.

Developing Coast Vulnerable Area Information Management System using Web GIS (Web GIS를 이용한 연안위험취약지역 정보시스템 구축)

  • Pak, Hyeon-Cheol;Kim, Hyoung-Sub;Jo, Myung-Hee
    • Journal of the Korean Association of Geographic Information Studies
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    • v.8 no.4
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    • pp.155-164
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    • 2005
  • The coast has been known as very vulnerable area. This area has nature disasters such as typhoon, tidal wave, flood and storm almost every year. In this study, coast vulnerable area information management system was developed to manage the coastal facilities and vulnerable area through Web GIS. This system is able to visualize the damage area and support the official work related to coast as efficient DSS(Decision Supporting System). Moreover, the foundation for domestic coast information management is expected by acquiring less cost and time. For this, GIS DB was first constructed by acquiring damage factor data such as typhoon, tidal wave, flood and storm. Then GIS analysis methods and high resolution satellite images are used to possibly present the results of retrieve as table, map, graph, inundation simulation in real time.

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