• Journal of the Korea Institute of Information and Communication Engineering
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• v.26 no.11
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• pp.1608-1614
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• 2022

As competition between universities intensifies due to the recent decrease in the number of students, it is recognized as an essential task of universities to predict students who are underperforming at an early stage and to make various efforts to prevent dropouts. For this, a high-performance model that accurately predicts student performance is essential. This paper proposes a method to improve prediction performance by removing or amplifying abnormal data in a classification prediction model for identifying underperforming students. Existing anomaly data processing methods have mainly focused on deleting or ignoring data, but this paper presents a criterion to distinguish noise from change indicators, and contributes to improving the performance of predictive models by deleting or amplifying data. In an experiment using open learning performance data for verification of the proposed method, we found a number of cases in which the proposed method can improve classification performance compared to the existing method.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.14 no.3
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• pp.21-31
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• 2014

In this paper, we propose VLC(visible light communication) based multi-hop multimedia data transmission system. The main contributions and features of the proposed system are as follows. First, the contribution of this research is to develope the LED communication based multi-hop transmission network system which can transmit multimedia data(audio data, video data) with long distance. Second, the developed system has the following features: In transmitter, audio data and video data are transmitted via multi-hops using two channels. The relay in audio channel receives digital audio signal by using photo diode and then transmits the signal to receiver after error checking and amplifying. The receiver receives the encoded audio data via photo diode and then converts to analog audio signal by using decoding and amplifying. The relay in video channel receives video signal by using photo diode and then amplify the video signal using OP-AMP and then transmits the signal to receiver. The receiver amplifies the received signal from photo diode and then sends it to the monitor. The performance evaluation of the proposed system is conducted in the laboratory with fluorescent light source. The results of the performance evaluation confirm that the system can provide high quality multimedia data transmission from transmiter to receiver via multi-hop relays in a long distance while we can see there are differences in the transmitted multimedia(audio and video) quality according to the used LED colors.

• Journal of the Institute of Electronics and Information Engineers
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• v.51 no.9
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• pp.46-53
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• 2014

In this paper, ku-band RF transceiver system is designed for the unmanned aerial vehicle(UAV) line-of-sight(LOS) datalink. The RF transceiver system is consisted of the transmitting and receiving unit, RF front-end unit, and high power amplification unit. The transmitting and receiving unit has the functions of frequency up/down converting and channel changing. The RF front-end unit has the functions of transmitting and receiving signal duplexing, antenna selection, small signal amplification, and frequency filtering excluding the receiving signal. The high power amplification unit has the functions of ku-band power amplification and transmitting power variation(High/Middle/Low/Mute). The frequency up/down converting of transmitting and receiving unit is designed by using the superheterodyne method. The RF transceiver system is designed to obtain the broadband and high linearity properties for the reliable transmission and reception of high data-rate and high speed data. Also, the channel changing function is designed to use selectively the frequency as the operation environment of UAV.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2012.07a
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• pp.102-103
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• 2012

본 논문에서는 다중 사용자 증폭재전송(amplify-and-forward) MIMO 중계 시스템을 위한 프리코딩(precoding) 기법을 제안한다. 제안된 프리코딩 기법에서는 블록 대각화(block diagonalization)를 통해 사용자간 간섭(inter-user interfereence)을 제거하고 기지국과 중계기에서의 전송전력(transmit power) 제한을 만족하면서 사용자 데이터 전송률(data rate)의 합이 최대화 되도록 한다. 모의실험결과를 통해 제안된 기법이 기존 기법에 비해 더 높은 사용자 데이터 전송률의 합을 달성함을 보이고 있다.

• Proceedings of the Korean Society for Bioinformatics Conference
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• 2003.10a
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• pp.139-146
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• 2003

암의 조기 발견 및 예후 예측을 위하여 마이크로어레이 데이터를 이용할 수 있다. 하지만 이를 분석하기 위해서는 40${\mu}g$ 이상의 RNA 샘플이 필요한데, 실제 임상 시료를 사용하는 경우 요구되는 충분한 양을 얻기가 어려운 단점이 있다. 따라서 소량의 RNA 샘플을 채취한 후 PCR 증폭 과정을 통하여 요구되는 양의 샘플을 얻을 수 있는 RNA 증폭 방법이 시도되고 있고, 이를 마이크로어레이 실험에 이용하기 위해서는 증폭 전후의 유사성이 보장되어야 한다. 본 논문에서는 증폭 RNA와 전체 RNA의 유사성을 비교하기 위한 새로운 방법으로 엔트로피 기반의 방법을 제시한다. 아울러 다양한 조건에 따라서 엔트로피값을 측정하여 세포주와 조직에서 엔트로피 값이 어떻게 사용될 수 있는지 체계적인 분석을 하였다.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.25 no.2
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• pp.303-311
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• 2015

DNS amplification is a new type of DDoS Attack and nowadays the attack occurs frequently. The previous studies showed the several detection ways such as the traffic analysis based on DNS queries and packet size. However, those methods have some limitations such as the uncertainty of packet size which depends on IP address type and vulnerabilities against distributed amplification attack. Therefore, we proposed a novel traffic analyzing algorithm using Success Rate and implemented the query analyzing system.

• Proceedings of the Korea Information Processing Society Conference
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• 2013.05a
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• pp.83-85
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• 2013

본 연구는 사용자가 센서를 의식하지 않고 편안하게 일상생활을 영위할 수 있는 비침습적 방식의 센서를 활용하여 향후 침대 위에 있는 사람의 움직임을 정량적으로 측정하고자 한다. 이러한 목적으로 필름 형태의 압전센서를 사용하는 센서 시스템을 구축하였으며, 본 논문에서는 구축된 시스템에서 필요한 전처리 과정을 제시한다. 본 연구에서 사용된 압전센서는 침대 매트리스 아래에 설치하였다. 사람의 움직임에 의한 압전센서의 출력 신호를 증폭하고 샘플링하여 PC로 전송하는 컨트롤러, 컨트롤러로부터 센서 데이터를 수신하고, 사용자에게 센서 데이터를 시각적으로 제시하는 모니터링 프로그램을 개발하였다. 본 연구에서는 컨트롤러에서의 노이즈 제거, 증폭, 샘플링 등의 전처리, 모니터링 프로그램에 의해 수집된 센서 데이터에 대한 이동 평균 필터, 불필요한 움직임이 없는 구간을 제거 후 움직임이 있는 구간 추출 등의 전처리 과정을 제시한다. 이러한 전처리 연산은 향후 침대 위 인체의 움직임을 정량적으로 측정하고, 행동유형을 식별하는데 기여하게 될 것이다.

• Journal of the Korean Data and Information Science Society
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• v.22 no.3
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• pp.371-380
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• 2011

The noise caused by a variety of reasons worsens the quality of input image when we use the images reproducing device. The basic difficulty to solve this problem is that the noise and the signal are difficult to be distinguished. Contrast enhancement such as unsharp masking is one of the most important procedures to improve the quality of input images. The conventional unsharp masking enhances the images by adding their amplified high frequency components. The noise component of the input images, however, also tends to be amplified due to the nature of the unsharp masking. This paper considers the block approach for detecting niose and image feature of the input image so that the unsharp masking could be adaptively applied accordingly. Simulation results show that it is made possible to enhance contrast of the image without boosting up the noisy components by applying the proposed algorithm.

• Journal of the Korean GEO-environmental Society
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• v.16 no.1
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• pp.17-27
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• 2015

Recently, Korean government has tried out to set up earthquake hazards prevention system. In the system, several geotechnical hazard maps including liquefaction hazard map and landslide hazard map for the whole country have drawn to consider the domestic seismic characteristics. To draw the macro liquefaction hazard map, big data of site investigations in metropolitan areas and provincial areas has to be verified for its application. In this research, we carried out site response analyses using 522 borehole site investigation data in S city during a desirable earthquake. The soil classification was separately compared to shear wave velocity considering the uncertainty of site investigation data. Probability distribution and statistical analysis for the results of site response analyses was applied to the feasibility study. Finally, we suggest a new site amplification coefficient, hereby presented with the similar results of liquefaction hazard mapping using the calculated liquefaction potential index by the site response analyses. Above-mentioned study will be expected to help to follow research and draw liquefaction hazard map in moderate seismic region.

• Journal of the Korean Society for Precision Engineering
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• v.2 no.1
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• pp.33-40
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• 1985

의료의 고도화를 위해서는 각종 생체현상의 계측기술이 중요시된다. 그림1과 같은 생체현상의 계측과 감시를 위한 계통도에서와 같이 생체에서 얻어지는 정보를 바르게 계측하여 평가하기 위해서는 앞에서 기술한 생체의 물성에 관한 지식이 필요하다. 다음에 전극, 변환기등의 각종 새로운 센서의 개발이 중요하며, 그리고서 얻어지는 데이터를 증폭하여 전송하는 기술과 데이터를 처리하여 표시하거나 기록하는 방법도 중요하다. 지금까지는 측정이 불가능하다고 생각되어진 것들을 가능하게 하기 위한 새로운 센서의 개발과 정성적으로만 측정되었던 것들까지도 정량적으로 측정되는 새로운 계측시스템이 고안되어 비관혈계측의 경향으로 연구되고 있다. 이들 센서들 중에는 생체의 활동전위를 검출하는 전극과, 활동전위 이외의 일반생체현상을 변환기(transducer)를 이용하여 전기신호로 변환하여 검출하는 센서가 있다.