• Proceedings of the Korea Water Resources Association Conference
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• 2005.05b
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• pp.454-458
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• 2005

여름철 집중강우시 유입되는 고탁수층은 저수지의 밀도성층으로 인하여 표수층 하부에 위치하며, 이를 적기에 배제하지 않을 경우에는 수평방향의 확산현상과 연직방향의 전도현상으로 인해 저수지 전역에 분포하게 되어, 탁수현상의 장기화를 유발한다. 일본 사메우라댐의 경우에는 1977년 9월 태풍 17호에 의한 집중호우로 대량의 고탁수가 유입되어 하류하천으로의 댐 방류수의 고탁도현상이 장기간 지속된 바 있다. 이와 같은 탁수장기화에 대한 저수지내 대책의 하나로서 홍수유입후 탁도가 높은 물을 단기간동안 방류하고, 갈수기에는 탁도가 낮은 물을 방류하는 선택취수 개념이 제안된 바 있다. 국내의 임하댐의 경우에도 2002년 태풍 '루사'와 2003년 태풍 '매미'로 인해 발생한 탁수가 전도현상을 거치며 저수지내 전수층에 확산됨으로써 댐방류수의 고탁도현상이 장기화된바 있다. 이로 인하여 댐하류에 위치한 안동시 용상정수장의 동절기 정수처리 장애로 2003년 11월이후 약 160여일동안 댐방류가 중단된 바 있다. 임하댐의 경우에도 탁수장기화에 대한 대책으로서 홍수기 고탁수층을 우선배제한 후, 저수지내에 유입되는 청수을 담수함으로써 이를 방지할 수 있다. 이러한 선택취수 기법은 동일한 수리동역학적 개념을 적용하여 하류하천의 냉해문제를 대비하기 위한 방법으로 표층의 온수를 선택방류하는 데에도 이용될 수 있다. 이와 같은 선택취수를 효율적으로 수행하기 위해서는 취수시설에 접근하는 밀도흐름을 정확하게 이해하고 있어야 한다. 또한 취수탑 인근에서의 온도 및 탁도 등의 연직분포를 실시간으로 파악할 수 있는 자동수질측정시스템이 구축되어 있어야 한다. 현재 임하댐의 경우, 하류하천의 수질을 고려한 효율적인 탁수배제를 위하여 상류 유입부 2개소, 발전취수탑 전면 1개소, 조정지댐 1개소 등 총 4개의 자동수질측정시스템이 설치되어 탁도와 온도가 실시간으로 모니터링되고 있으며, 향후 강우시 저수지에서의 밀도흐름을 보다 정밀하게 모니터링하기 위하여 저수지내 4개의 주요지점에 추가적으로 설치될 예정이다. 이와 같은 자동측정시스템과 더불어 주기적인 세부 수질조사를 실시하면 저수지내의 온도성층 변화와 탁수층 분포를 매우 정확하게 파악할 수 있으며, 호소의 수질모형과 연계하여 강우시 탁수 도달시간과 탁수량을 사전에 예측할 수도 있다. 또한 이와 같은 기초적인 정보를 바탕으로 하류하천의 탁수 피해를 최소화할 수 있는 선택취수탑의 운영방안을 수립할 수 있다 본 연구에서는 이를 위해 선택취수탑 주위의 성층흐름을 기존의 실험자료와 수치해석을 통하여 분석하였고, 온도성층구조나 취수구의 위치변화에 따른 방류수 수질특성을 조사하였다.

• Journal of the Korea Convergence Society
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• v.8 no.8
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• pp.9-15
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• 2017

With the development of semiconductor integration technology, central processing units and storage devices have been miniaturized and performance has been rapidly developed, interconnection network technology is becoming a more important factor in terms of the performance of high performance computing system. In this paper, we analyze the trend of interconnection network technology used in high performance computing. Interconnect technology, which is the most widely used in the Supercomputer Top 500(2017. 06.), is an Infiniband. Recently, Ethernet is the second highest share after InfiniBand due to the emergence of 40/100Gbps Gigabit Ethernet technology. Gigabit Ethernet, where latency performance is lower than InfiniBand, is preferred in cost-effective medium-sized data centers. In addition, top-end HPC systems that demand high performance are devoting themselves from Ethernet and InfiniBand technologies and are attempting to maximize system performance by introducing their own interconnect networks. In the future, high-performance interconnects are expected to utilize silicon-based optical communication technology to exchange data with light.

• Journal of the Institute of Electronics and Information Engineers
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• v.50 no.3
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• pp.102-112
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• 2013

In this paper, two step processing method of contour extraction and complement which contain hexagonal shape for low contrast and noisy images is proposed. This method is based on the combination of Laplacian-Gaussian filter and an idea of filters which are dependent on the shape. At the first step, an algorithm which has six masks as its extractors to extract the hexagonal edges especially in the corners is used. Here, two tricorn filters are used to detect the tricorn joints of hexagons and other four masks are used to enhance the line segments of hexagonal edges. As a natural image, a corneal endothelial cell image which usually has regular hexagonal form is selected. The edge extraction of hexagonal shapes in corneal endothelial cell is important for clinical diagnosis. The proposed algorithm and other conventional methods are applied to noisy hexagonal images to evaluate each efficiency. As a result, this proposed algorithm shows a robustness against noises and better detection ability in the aspects of the output signal to noise ratio, the edge coincidence ratio and the extraction accuracy factor as compared with other conventional methods. At the second step, the lacking part of the thinned image by an energy minimum algorithm is complemented, and then the area and distribution of cells which give necessary information for medical diagnosis are computed.

• Journal of the Korean Geophysical Society
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• v.10 no.1
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• pp.1-12
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• 2007

A method to quickly estimate broadband moment magnitudes (Mwp) to warn regional and teleseismic tsunamigenic earthquakes is tested for application of the method to the different seismic observation environment. In this study, the Mwp is calculated by integrating far-field P-wave or pP-wave of vertical component of displacement seismograms in time domain from earthquakes, having magnitude greater than 5.0 and occurred in and around the Korean peninsula from 2000 to 2006. We carefully set up the size of the time window for the computations to exclude S wave phases and other phases following after the P wave phase. The P wave velocities and the densities from the averaged Korean crustal model are used in the computations. Instrumental correction was performed to remove dependency on the seismograph. The Mwp after the instrumental correction is about 0.1 greater than the Mwp before the correction. The comparison of our results to the those of foreign agencies such as JMA and Havard CMT catalogues shows a higher degree of similarity. Thus our results provide an effective tool to estimate the earthquake size, as well as to issue the necessary information to a tsunami warning system when the effective earthquake occurs around the peninsula.

• Journal of the Korean Geotechnical Society
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• v.21 no.5
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• pp.83-92
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• 2005

The aim of this study was to investigate damage conditions of cut slope structures due to acid rock drainage (ARB) and to assess the acid production potential of various rocks. Acid rock drainage is produced by the oxidation of sulfide minerals contained in coal mine zone and mineralization belt of Pyeongan supergroup and Ogcheon group, pyrite-bearing andesite, and Tertiary acid sulfate soils in Korea. Most of cut slopes producing ARB have been treated with shotcrete to reduce ARD. According to the field observations, ARD had an adverse effect on slope structures. The corrosion of shotcrete, anchors and rock bolts and the bad germination and growth diseases of covering plants due to ARD were observed in the field. The concentration of heavy metals and pH of ARD from cut slope exceeded the environmental standard, indicating a high potential of environmental pollution of surrounding soil, surface water and ground water by the ARD. According to acid base accounting (ABA) of the studied samples, hydrothermally altered volcanic rocks, tuffs, coaly shales, tailings of metallic mine had a relatively high potential of acid production but gneiss and granite had no or less acid production potential. It is expected that the number of cut slopes will increase hereafter considering the present construction trend. In order to reduce the adverse effect of ARD in construction sites, we need to secure the data base for potential ARD producing area and to develop the ARD reduction technologies suitable.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.28 no.11
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• pp.902-915
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• 2017

In recent years, mobile devices have become increasingly multi-functional and high performance, resulting in a dramatical increase in processing speed. On the other hand, the size of device is reduced, circuits inside the device are more easily exposed to electromagnetic interference radiated from antenna or adjacent circuits, degrading the system performance. To prevent this, it is necessary to design the device considering the electromagnetic characteristics with EM simulation at the design stage of product. However, the EM simulation takes a long analysis time and require high-level system resources for fast analysis. In this paper, an equivalent circuit modeling method for a round wire is proposed using a PEEC method and the electromagnetic coupling from a dipole antenna to a transmission line is analyzed in frequency domain. And compared with the result of electromagnetic simulator. As a result, PEEC method shows good agreement with those of electromagnetic simulation, in a much more short time.

• Korean Journal of Remote Sensing
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• v.38 no.5_1
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• pp.485-496
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• 2022

This study is for the software implementation to generate atmospheric and surface reflectance products from RapidEye satellite imagery. The software is an extension based on Orfeo Toolbox (OTB) and an open-source remote sensing software including calibration modules which use an absolute atmospheric correction algorithm. In order to verify the performance of the program, the accuracy of the product was validated by a test image on the Radiometric Calibration Network (RadCalNet) site. In addition, the accuracy of the surface reflectance product generated from the KOMPSAT-3A image, the surface reflectance of Landsat Analysis Ready Data (ARD) of the same site, and near acquisition date were compared with RapidEye-based one. At the same time, a comparative study was carried out with the processing results using QUick Atmospheric Correction (QUAC) and Fast Line-of-sight Atmospheric Analysis of Spectral Hypercubes (FLAASH) tool supported by a commercial tool for the same image. Similar to the KOMPSAT-3A-based surface reflectance product, the results obtained from RapidEye Extension showed accuracy of agreement level within 5%, compared with RadCalNet data. They also showed better accuracy in all band images than the results using QUAC or FLAASH tool. As the importance of the Red-Edge band in agriculture, forests, and the environment applications is being emphasized, it is expected that the utilization of the surface reflectance products of RapidEye images produced using this program will also increase.

• The Journal of the Acoustical Society of Korea
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• v.41 no.3
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• pp.319-325
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• 2022

The variation of utterance lengths is a representative factor that can degrade the performance of speaker verification systems. To handle this issue, previous studies had attempted to extract speaker features from various branches or to use convolution layers with different receptive fields. Combining the advantages of the previous two approaches for variable-length input, this paper proposes integrated receptive field diversification that extracts speaker features through more diverse receptive field. The proposed method processes the input features by convolutional layers with different receptive fields at multiple time-axis branches, and extracts speaker embedding by dynamically aggregating the processed features according to the lengths of input utterances. The deep neural networks in this study were trained on the VoxCeleb2 dataset and tested on the VoxCeleb1 evaluation dataset that divided into 1 s, 2 s, 5 s, and full-length. Experimental results demonstrated that the proposed method reduces the equal error rate by 19.7 % compared to the baseline.

• Journal of the Korean Geotechnical Society
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• v.22 no.4
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• pp.41-49
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• 2006

This paper demonstrates the feasibility of using shallow S-wave, high-resolution seismic reflection surveys to characterize geological structure and stratigraphy of basement rocks for civil engineering purposes. S-wave seismic reflections from depths less than 20 m were recorded along the top of steep readout slopes. Seismic reflection data were recorded using a standard CDP acquisition method with a 24-channel seismograph and a sledge-hammer SH-wave source. The data were acquired using a split-spread source-receiver geometry with a 2 m shot-and-receiver interval, and then were processed to enhance S/N ratio of the data, to improve resolvable power of the seismic section, and to get velocity information of the basement rock. The final seismic reflection profiles using the CDP technique has imaged surfaces as shallow as less than 1m and resolved beds as thin as 1m. The migrated reflection sections possess sufficient quality to correlate the prominent reflection events to the bedding planes and faults identified on the readout outcrops. Similar S-wave reflection surveys could also be used to produce the necessary details of a geological structure of shallow bedrocks to pinpoint optimum locations for monitor wells of civil engineering purposes.

• KIPS Transactions on Software and Data Engineering
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• v.4 no.11
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• pp.509-520
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• 2015

College Scholastic Ability Test(CSAT) is a primary test to evaluate the study achievement of high-school students and used by most universities for admission decision in South Korea. Because its level of difficulty is a significant issue to both students and universities, the government makes a huge effort to have a consistent difficulty level every year. However, the actual levels of difficulty have significantly fluctuated, which causes many problems with university admission. In this paper, we build two types of data-driven prediction models to predict correct answer rate and to identify significant factors for CSAT English test through accumulated test data of CSAT, unlike traditional methods depending on experts' judgments. Initially, we derive candidate question-specific factors that can influence the correct answer rate, such as the position, EBS-relation, readability, from the annual CSAT practices and CSAT for 10 years. In addition, we drive context-specific factors by employing topic modeling which identify the underlying topics over the text. Then, the correct answer rate is predicted by multiple linear regression and level of difficulty is predicted by classification tree. The experimental results show that 90% of accuracy can be achieved by the level of difficulty (difficult/easy) classification model, whereas the error rate for correct answer rate is below 16%. Points and problem category are found to be critical to predict the correct answer rate. In addition, the correct answer rate is also influenced by some of the topics discovered by topic modeling. Based on our study, it will be possible to predict the range of expected correct answer rate for both question-level and entire test-level, which will help CSAT examiners to control the level of difficulties.