• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.19 no.4
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• pp.81-99
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• 2020

Origin-destination data have been collected and utilized for demand analysis and service design in various fields such as public transportation and traffic operation. As the utilization of big data becomes important, there are increasing needs to store raw origin-destination data for big data analysis. However, it is not practical to store and analyze the raw data for a long period of time since the size of the data increases by the power of the number of the collection points. To overcome this storage limitation and long-period pattern analysis, this study proposes a methodology for compression and origin-destination data analysis with the compressed data. The proposed methodology is applied to public transit data of Sejong and Seoul. We first measure the reconstruction error and the data size for each truncated matrix. Then, to determine a range of principal components for removing random data, we measure the level of the regularity based on covariance coefficients of the demand data reconstructed with each range of principal components. Based on the distribution of the covariance coefficients, we found the range of principal components that covers the regular demand. The ranges are determined as 1~60 and 1~80 for Sejong and Seoul respectively.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.12 no.4
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• pp.81-93
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• 2012

We propose efficient mobility management schemes based on pointer forwarding for Proxy Mobile IPv6 Networks(PMIPv6) with the objective to reduce the overall network traffic incurred by mobility management and packet delivery. The proposed schemes are per-user-based, i.e., the optimal threshold of the forwarding chain length that minimizes the overall network traffic is dynamically determined for each individual mobile user, based on the user's specific mobility and service patterns. We demonstrate that there exists an optimal threshold of the forwarding chain length, given a set of parameters characterizing the specific mobility and service patterns of a mobile user. We also demonstrate that our schemes yield significantly better performance than schemes that apply a static threshold to all mobile users. A comparative analysis shows that our pointer forwarding schemes outperform routing-based mobility management protocols for PMIPv6.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.10 no.6
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• pp.594-600
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• 2017

The new design methodology of prediction model and pattern classification, which is based on the dimension reduction algorithm called principal component analysis, is introduced in this paper. Principal component analysis is one of dimension reduction techniques which are used to reduce the dimension of the input space and extract some good features from the original input variables. The extracted input variables are applied to the prediction model and pattern classifier as the input variables. The introduced prediction model and pattern classifier are based on the very simple regression which is the key point of the paper. The structural simplicity of the prediction model and pattern classifier leads to reducing the over-fitting problem. In order to validate the proposed prediction model and pattern classifier, several machine learning data sets are used.

• Journal of the Korea Society of Computer and Information
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• v.6 no.2
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• pp.41-47
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• 2001

In this paper, I propose a detection algorithm that can reliably separate moving objects from noisy background in the image sequence received from a camera at the fixed position. The proposed algorithm consists of four processes: generation of the difference image between the input image and the reference image. multilevel quantization of the difference image, and multistage merging in the quantized image, detection of the moving object using a back propagation in a neural network. The test results show that the proposed algorithm can detect moving objects very effectively in noisy environment.

• The Journal of Korean Academy of Prosthodontics
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• v.54 no.1
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• pp.1-7
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• 2016

Purpose: The aim of this study was to evaluate the effect of increased vertical dimension of occlusion on lower facial changes by facial type. Materials and methods: Lateral cephalograms from 261 patients were obtained and classified by sagittal (Class I, II, and III) and vertical (hypodivergent, normodivergent, and hyperdivergent) facial patterns. Retrusive displacement of soft tissue Pogonion and downward displacement of soft tissue Menton were measured in each group after 2 mm of vertical dimension of occlusion was increased at the lower central incisor using a virtual simulation program. The ratio of both displacements was calculated in all groups. The statistical analysis was done by 2-way ANOVA and Post hoc was done by Tukey test (5% level of significance). Results: Retrusive displacement of soft tissue Pogonion in Class III group was statistically different compared to Class I and II, and in vertical facial groups all 3 groups were significantly different (P<.05). Downward displacement of soft tissue Menton showed statistically significant difference between all sagittal groups and vertical groups (P<.05). The ratio of both displacements showed statistically significant difference in all sagittal groups and vertical groups (P<.05), and Class II hyperdivergent group had the highest value. Conclusion: Lower facial change was statically significant according to the facial type when vertical dimension of occlusion increased. Class II hyperdivergent facial type showed the highest ratio after increase in vertical dimension of occlusion.

• Information and Communications Magazine
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• v.30 no.2
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• pp.11-17
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• 2013

5세대 이동통신 시스템은 100Gbps급의 용량 증대를 목표로 하고 있으며, 이를 지원하기 위해서 무선 백홀에서 10GHz 이상 대역을 활용하는 연구가 시도되고 있다. 또한, 사용자를 지원하기 위한 무선 접속망에서는 고용량의 용량 증대 달성을 위해서 massive MIMO 등의 기술들이 활용될 수 있다. 하지만 5GHz 이하의 대역에서 많은 안테나를 활용하기 위해서는 공간상의 제약이 발생하기 때문에 이를 극복하기 위해서 집적화된 안테나에 대한 연구가 필요하다. 집적화된 안테나의 방사패턴에 따른 채널 특성은 기존 채널 특성과는 많은 차이가 있으며 이론적인 연구에는 한계가 발생할 수밖에 없어서 실제 검증 시스템의 구현을 통해서 측정을 통한 분석 연구가 필요하다. 이에 따라 본 논문에서는 집적화된 안테나를 기반으로 하는 무선 접속망의 설계를 위해서 SDR 기술인 GNURadio와 USRP 보드를 활용한 시스템을 설계하고 성능 분석한 결과를 제시한다. 본 연구를 통해서 집적화된 안테나 기반의 용량에 대한 성능이 동일한 수신 SNR 관점에서는 기존 MIMO의 성능과 비교해서 큰 차이가 없음을 보인다.

• Proceedings of the Korean Information Science Society Conference
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• 2004.04b
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• pp.940-942
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• 2004

한국어 텍스트 음성합성에서 문장 기호의 문자화에 나타나는 오류는 기호의 중의성에 기인한다. 선행연구에서 규칙에 기반하여 중의성을 해결하는 방안이 제안되었으나 여전히 기호는 다양한 문맥에서 높은 중의성을 가지고 문자화된다. 따라서 본 연구에서는 신문 텍스트에 나타나는 문장 기호 중 이음표의 문자화를 이음표를 포함한 어절의 패턴, 패턴의 좌우에 위치하는 어절 정보 및 휴리스틱스 자질을 학습하여 제시된 이음표의 문자화의 중의성을 해소하는 방안을 제안하였다. 이를 위해 국내 1개 일간지 2년 치 기사에서 이음표를 포함한 어절 49,000여 개를 임의 추출하여 분석하였고, 분석된 자질을 자동추출하여 결정 트리를 구성하였다. 실험 결과, 96.2%～97.7%의 정확도를 보였다.

• Journal of Broadcast Engineering
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• v.8 no.2
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• pp.181-197
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• 2003

Notion Compensation(MC) technique using Sub-Band Coding with the hierarchical structure is efficient to estimate real motion. In the hierarchical pyramid method, low-band MC pyramid method is popular, where the upper layer estimate the glover motion and next lower layer estimate the local motion. The low-band MC pyramid scheme has two problems. First, because the quantization errors at lower layer are accumulated when using coding and quantizing, it is impossible to search the exact Motion Vector(MV) Second, because of the top-down search problem in the hierarchical structure, MV mismatch in upper layer causes serious MV in lower layer So. we propose new hierarchical MC pyramid method based on edge classification. In this Paper, we show that the performance of proposed Pass-band motion compensation pyramid technique is better than low-band motion compensation pyramid. Also, in the pyramid motion estimation, we propose initial MV estimation scheme based on the edge-pattern classification. As a result, we find that PSNR was increased.

• Information and Communications Magazine
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• v.25 no.7
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• pp.34-39
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• 2008

본고에서는 제주 택시 텔레매틱스 시스템에서 제공하는 서비스에 대해 소개하며 이 시스템의 구축과 운영상황을 소개한다. 또 서비스를 고도화하기 위한 플랫폼과 이동이력 데이터의 활용방안에 대해 고찰한다. 제주 택시 텔레매틱스 시스템은 각 차량의 위치를 파악하고 고객의 콜에 대해 가장 가까운 차량을 배차하는 기능을 가지며 대용량 데이터에 대한 고속의 처리 기능을 지원해야 한다. 또 각 차량에서 보고된 위치 정보는 기본적으로 경도, 위도 외에도 속도와 방향에 대한 정보가 포함되므로 링크의 통행속도 산출이나 배차 지점의 분석, 탑승 패턴의 추이, 배차 시간의 분석 등 다양한 부가정보를 산출할 수 있다.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2009.05a
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• pp.149-151
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• 2009

본 논문에서는 이동이 힘들거나 자주 건강관리가 필요한 노약자나 임산부들에게 좀 더 신속하고 빠른 진단 서비스를 제공하기 위해 단말기에서 맥박을 측정하여 Bluetooth를 통하여 모바일 폰에 전송하고 원격에서 모바일 폰을 통해 전송된 맥박파형 데이터를 분석하고자 한다. 팔목에 착용하는 형태의 단말기에는 체온측정을 위한 온도센서, 맥박측정을 위한 Piezo Vibration Sensor, 움직임 체크를 위한 가속도센서와 자이로센서가 장착되어있다. 이 센서들을 이용하여 측정된 데이터들을 모바일 폰의 Wi-Fi를 통해 서버로 전송하여 원격에서 의사가 담당환자를 체크할 수 있도록 하고자 한다.