• Journal of the Korea Institute of Information and Communication Engineering
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• 제19권12호
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• pp.2844-2851
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• 2015

How to recover from the multiple 2D images into 3D object has been widely studied in the field of computer vision. In order to improve the accuracy of the recovered 3D shape, it is more important that noise must be minimized and the number of image frames must be guaranteed. However, potential noise is implied when tracking feature points. And the number of image frames which is consisted of an observation matrix usually decrease because of tracking failure, occlusions, or low image resolution, and so on. Therefore, it is obviously essential that the number of image frames must be secured by recovering the missing feature points under noise. Thus, we propose the analytic approach which can control directly the error distance and orientation of missing feature point by the geometrical properties under noise distribution. The superiority of proposed method is demonstrated through experimental results for synthetic and real object.

• The KIPS Transactions:PartC
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• 제17C권6호
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• pp.491-498
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• 2010

Wi-Fi based vehicle-to-infrastructure (V2I) communication is an emerging solution to improve the safety, traffic efficiency, and comfort of passengers. However, due to the high mobility of vehicles and the limited coverage of Wi-Fi APs, the V2I system may suffer from frequent handoffs although roadside APs can support cost effective Internet connectivity. Such problem of V2I systems can be overcome with Mobile AP (MAP) platform. The MAPs yield longer service duration by moving along with vehicles, yet they provide a lower link capacities than the roadside APs. In this paper, we propose a new association control mechanism that effectively determines whether the vehicle will select a fixed roadside-AP or a nearby MAP in mobile vehicular network environments. We consider both the achievable link bandwidth and available connection duration as a selection criterion and provide their run-time estimation method. Extensive simulation using real traces show significant performance improvements.

• Tunnel and Underground Space
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• 제13권4호
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• pp.294-303
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• 2003

The structural behaviour of rock mass structure, such as tunnel or slope is critically dependent on the various characteristics of discontinuities. Therefore, it is important to survey and analyze discontinuities correctly for the design and construction of rock mass structure. One inevitable Procedure of discontinuity survey and analysis is joint set identification from a lot of raw directional joint data. The identification procedure is generally done by a graphical method. This type of analysis has some shortcomings such as subjective identification results, inability to use extra information on discontinuity, and so on. In this study, a computer program for joint set identification based on the fuzzy clustering algorithm was implemented and tested using two kinds of joint data. It was confirmed that fuzzy clustering method is effective and valid for joint set identification and estimation of mean direction and degree of clustering of huge joint data through the applications.

• Journal of Korean Society of Transportation
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• 제33권2호
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• pp.145-158
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• 2015

A network connectivity has been regarded as a key element to strengthen a business competitive power in the aviation industry, so many airport authorities try to attract the new airlines and scheme out new air routes. With this trend, a study for an induced travel demand estimation methodology is needed. This study introduces a demand estimation method, especially for a new air route to a promising destination. With the results of previous studies, the derived demand is classified into four types - Local, Beyond, Behind and Bridge. The explanatory variables are established for each type of demand and the main independent variables are composed of distance, ratio of detour, and relative capacity compared with other airports. The equations using such variables and statistically significant coefficients are suggested as the model to make an estimation of derived demand for a new route. Therefore this study will be expected to take an initial step for all related parties to be involved more deeply into developing new air routes to enhance network connectivity.

• Journal of Korea Multimedia Society
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• 제4권4호
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• pp.306-315
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• 2001

In noise reduction method from noisy speech for speech recognition in noisy environments, conventional spectral subtraction method has a disadvantage which distinction of noise and speech is difficult, and characteristic of noise can't be estimated accurately. Also, noise reduction method in the wavelet transform domain has a disadvantage which loss of signal is generated in the high frequency domain. In order to compensate theme disadvantage, this paper propose spectral subtraction method in continuous wavelet transform domain which speech and non- speech intervals is distinguished by standard deviation of wavelet coefficient, and signal is divided three scales at different scale. The proposed method extract accurately characteristic of noise in order to apply spectral subtraction method by end detection and band division. The proposed method shows better performance than noise reduction method using conventional spectral subtraction and wavelet transform from viewpoint signal to noise ratio and Itakura-Saito distance by experimental.

• Journal of Advanced Navigation Technology
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• 제15권6호
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• pp.1241-1249
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• 2011

There are TOA, TDOA and AOA method to estimate the position of the electromagnetic wave transmitter by using the multiple receivers at the fixed position. Among these methods, AOA method is suitable for the jammer localization system. Because TOA method can be adopted for the clocks of the transmitter and the receiver are synchronized each other, and TDOA method can be only adopted for a broad-band jamming signal. This paper, therefore, analyzes the characteristics of the AOA measurements and the sensitivity of the positioning performance according to the system design parameters. Based on the analyzed results, the jammer localization system to meet the desired performance is designed, and it has been checked that the positioning error for the jammer located at a distance of 10km is lower than 38m through the simulation results.

• The Journal of the Korea Contents Association
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• 제6권10호
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• pp.107-113
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• 2006

Error Concealment method for Intra frames in H.264 reconstructs the lost block by computing weighted average value of the boundary pixels of the neighboring blocks; up, bottom, left and right blocks. However a simple average of pixel values of the neighboring blocks for Intra frames in H.264 leads to excessive blurring and degrades the picture quality severely. To solve this problem, in this paper we estimate the dominant edge of lost block using the pixel values of the neighboring blocks and reconstruct the pixel values by choosing adaptive interpolation between directional interpolation and weighted average interpolation considering the result value of the interference function based on statistics. Finally directional interpolation method improves by determining the dominant edge direction considering the relation of the dominent edge and the edges of neighboring blocks. Experiments show improvement of picture quality of about $0.5{\sim}2.0dB$ compared with the method of H.264.

• Journal of Korean Society for Atmospheric Environment
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• 제26권1호
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• pp.48-56
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• 2010

Recently it has reported that the motorcycle is a major source of air pollution in urban area by many studies. But the air pollution emission from motorcycle has been high uncertainty due investigation of a lack of activity data and emission factors in Korea. So in this study, the population of moped and VKT (Vehicle kilometers travelled) of motorcycle are investigated for calculation of the emission from this source categories. As the results, the population of moped is estimated as about 400, 000 and corresponded as 23% of registrated motorcycle which is larger than 50 cc in engine displacement. And it is found that the VKT of moped and motorcycle are investigated as 19.1 km/day and 32.3 km/day. Annual air pollution emission from motorcycle and moped are estimated by investigated VKT and updated emission factors. The nationwide emissions of PM_{10}, CO, $NO_x$, VOC are calculated as 910 ton/yr, 208, 198 ton/yr, 3, 032 ton/yr and 25, 575 ton/yr in 2008. The contribution ratio of CO, VOC emission from these sources are estimated as 29%, 24% in on-road transport sector and it is confirmed that motorcycle and moped are major air pollution sources in urban area.

• Journal of Satellite, Information and Communications
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• 제10권1호
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• pp.17-21
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• 2015

In this paper, we introduce satellite communication for new wireless disaster network to be built on the basis of amateur radio HR (HAM Radio) as a wireless package system, and channel environments of a D2D terminal that tries to connect and communicate with the wireless disaster network. In this disaster network, we propose a LOS component ratio based adaptive channel modeling approach to accurately estimate a variety of channels whose the D2D terminal could have and smoothly transfer to the level of multimedia data based on the Okumura-Hata channel model. As a result of computer simulation, performance of the proposed method was compared with the that of Okumura-Hata model of open area and urban area model and we were confirmed that there is a gain of BER performance from the results of the computer simulation.

• Journal of KIISE:Computing Practices and Letters
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• 제16권4호
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• pp.457-461
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• 2010

Even though face recognition researches have been developed for a long ago, there is no practical face recognition system in real life. It is caused by several real situations where non-facial components such as glasses, scarf, and hair occlude facial components while facial images in a face database are well designed. This occlusion decreases recognition performance. Previous approaches in recent years have tried to solve non-facial components but have not resulted in enough performance. In this paper, we propose a method to handle this problem based on support vector data description, which trains the hyperball in feature space to find the minimum distance estimating the approximated face. In order to evaluate its performance and validate the effectiveness of the proposed method, we make several experiments and the results show that the proposed method has a considerable effectiveness.