• Journal of Industrial Convergence
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• v.17 no.4
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• pp.131-137
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• 2019

In infrastructure wireless mesh networks (WMNs), in order to improve mobile users' satisfaction for the given cache hit ratio, we investigate an User centric Cache Allocation (UCA) scheme while reducing cache cost in a mesh router (MR) and expected transmission time (ETT) for content search in cache. To minimize ETT values of mobile users, a genetic algorithm based UCA (GA-UCA) scheme is provided. The goal is to maximize mobile users' satisfaction via our well defined utility, which considers content popularity and the number of mobile users. Finally, through solving optimization problem we show the optimal cache can be allocated for UCA and GA-UCA. Besides, a WMN provider can find the optimal number of mobile users for user centric cache allocation in infrastructure WMNs.

• Journal of the Korean Society of Physical Medicine
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• v.8 no.1
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• pp.59-69
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• 2013

연구목적: 본 연구는 만성 뇌졸중 환자를 대상으로 흡기근 저항훈련이 횡격막 두께와 폐기능 및 흉곽 확장에 미치는 효과를 알아보고자 수행하였다. 연구방법: 연구 대상자는 총 29명(남자 17명, 여자 12명)으로 흡기근 저항훈련군(15명)과 대조군(14명)으로 분류하였다. 모든 대상자는 6개월 이상된 만성 뇌졸중 환자로 일반적인 신경발달치료를 받고 있으며, 같은 기간 동안 흡기근 저항훈련군에 역치부하 흡기근육 단련기(threshold IMT device)를 제공하고 주 3회${\times}$1회 20분씩 6주간 시행하였다. 마비측과 비마비측 횡격막 두께측정을 위해 초음파의 7.5MHz linear probe를 사용하여 최대 흡기시(Tdi.con)와 휴식시(Tdi.rel)의 두께를 측정하고 수축률(TR)을 계산하였다. 또한 폐 활량계를 사용하여 노력성 폐활량을 측정하였으며, 줄자를 사용하여 흉곽 확장을 측정하였다. 연구결과: 6주간 중재 후 흡기근 저항훈련군에서 최대흡기시 횡격막 두께(Tdi.con)와 수축률(TR)은 유의한 증가를 보였다(p<.05). 1초간 노력성 호기량 ($FEV_1$)과 최대 호기 속도(PEF)도 유의한 증가를 보였으나(p<.05), 노력성 폐활량(FVC)과 1초간 노력성 호기량의 노력성 폐활량에 대한 비($FEV_1$/FVC), 흉곽 확장은 유의한 증가는 보이지 않았다(p>.05). 결론: 본 연구는 만성뇌졸중 환자를 대상으로 흡기근 저항훈련의 적용이 횡격막의 수축력과 폐기능 및 흉곽 확장력을 향상시켜 호흡근의 협응력을 증가시키고, 비활동성으로 인해 감소된 운동내성을 증가하게 함으로써 향후 재활에서 만성 뇌졸중 환자에게 2차적인 기능향상에 도움을 줄수 있을 것으로 보여진다.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.11 no.3
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• pp.70-80
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• 2012

In Vehicular Ad-hoc Network(VANET) which constructs networks without fixed infrastructure among vehicles, network topology is frequently changed due to high mobility. In case of urban model, communication disconnections caused by interruptions of communication propagation such as buildings and constructions could be often occurred. Therefore, in VANET environment a routing protocol to complement its characteristics is needed. This paper suggests an algorithm to improve the transmission performance at intersections by approaching of the distance-based broadcasting which utilizes the information of vehicle's position. By using relative velocity among vehicles, it makes the stability of route decision improved and reduces packet collisions through graded priorities in the intersection, and simultaneously improves the performance of data rate. It can be seen that the performance compared with previous algorithm is significantly improved when using the suggested algorithm in the urban traffic environment.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.32 no.8A
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• pp.827-835
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• 2007

In this paper, the extension method of data transmission range as adapting AAS(Adaptive Antenna Systems) in ECMA(European Computer Manufacturers Association) standard MB-OFDM(MultiBand-Orthogonal Frequency Division Multiplexing) UWB systems is proposed, and the complementary beamforming method which can solve hidden beam problem when we adapt AAS in CSMA/CA(Carrier Sense Multiple Access with Collision Avoidance) systems is proposed. To design the complementary beamforming, Gram-Schmidt orthogonalization is utilized, whose beam pattern exhibits perfect nulling at the main beam angles and provides uniform power for detection of channel utilization out of main beam. The proposed method can be utilized with any arbitrary beamforming when we make main beamforming. Through computer simulation, it can be shown that proposed AAS and complementary beamforming increase data transmission range from 2m to 3.95m in 480Mbps data transmission system and increase throughput about 20% as compared with general UWB AAS systems.

• Journal of the Institute of Electronics Engineers of Korea CI
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• v.48 no.5
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• pp.33-41
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• 2011

In this paper, we propose a lossless compression scheme for cloud point data of the target construction by using doubleness and decreasing useless information of cloud point data. We use Hough transform to find the horizontal angle between construction and terrestrial LIDAR. This angle is used for the rotation of the cloud point data. The cloud point data can be parallel to x-axis, then y-axis doubleness is increased. Therefore, the cloud point data can be more compressed. In addition, we apply two methods to decrease the number of cloud point data for useless information of them. One is decimation of the cloud point data, the other is to extract the range of y-coordinates of target construction, and then extract the cloud point data existing in the range only. The experimental result shows the performance of proposed scheme. To compress the data, we use only the position information without additional information. Therefore, this scheme can increase processing speed of the compression algorithm.

• Journal of Advanced Navigation Technology
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• v.17 no.6
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• pp.726-735
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• 2013

This paper proposed face recognition methods about performance improvement of the face recognition using the properties of wavelet transform. Using discrete wavelet transform is Daubechies D4 filter that is similar to mother wavelet transform. For discrete wavelet transform method, In this case, by using LL subband only we can reduce processing time and amount of memory in recognition processing. To improve recognition ratio without further loss of 2 dimensional data changing, We applies 2D LDA. We perform SVM training algorithm to the feature vector obtained by 2D LDA. Experiment is performed using ORL database set and Yale database set by Matlab program. Test result shows that proposed method is superior to existence methods in recognition rate and performance time.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.25 no.12
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• pp.1835-1845
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• 2021

To accurately identify black ice and warn the drivers of information in advance so they can control speed and take preventive measures. In this paper, we propose a lightweight black ice detection network based on infrared road images. A black ice recognition network model based on CNN transfer learning has been developed. Additionally, to further improve the accuracy of black ice recognition, an enhanced lightweight network based on MobileNetV2 has been developed. To reduce the amount of calculation, linear bottlenecks and inverse residuals was used, and four bottleneck groups were used. At the same time, to improve the recognition rate of the model, each bottleneck group was connected to a 3×3 convolutional layer to enhance regional feature extraction and increase the number of feature maps. Finally, a black ice recognition experiment was performed on the constructed infrared road black ice dataset. The network model proposed in this paper had an accurate recognition rate of 99.07% for black ice.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.11 no.3
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• pp.235-240
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• 2018

FTN method which transmits signals faster the Nyquist rate is representative method for improving throughput efficiency sacrificed performance due to inter-symbol interference. To compensate performance loss, in this paper, we propose a multiband FTN method which split the coded bits into several bands and transmits signals applying FTN method. As coded bits are being assigned different bands, number of samples per bit of each band is increased, it induced performance improvement by noise averaging effect. In the simulations, compared the performance of single band FTN method and multiband FTN method when the interference rate is 25%. The results of simulation show the performance of proposed method is better than that of single band FTN one by 0.3dB~0.5dB.

• Proceedings of the Korean Information Science Society Conference
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• 2004.10b
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• pp.739-741
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• 2004

얼굴인식 기술 분야에 있어서 Haar-like feature를 이용한 얼굴 검출 알고리즘은 많은 관련 알고리즘 중에 매우 빠른 트레이닝 시간과 처리속도 향상의 장점을 가지고 있다 그러므로 특히 동영상에서의 얼굴 검출에서 유용하게 쓰일 수 있다. 이러한 방법으로 검출된 얼괄 데이터는 HMM(Hidden Markov Model)알고리즘을 이용하여 이미 트레이닝된 얼굴 데이터베이스와의 비교를 통해 얼굴인식에 있어서 가장 확률이 높은 사람을 본인의 얼굴로 인증하는 신원 확인 시스템을 구현할 수 있게 된다. 신원 확인 시스템에 있어서 얼굴 검출 율이나 신원 확인 성공률은 모두 학습 과정에 의해 결정되기 때문에 얼마나 많은 학습을 효율적으로 하느냐에 따라 성능이 좌우된다. 이러한 시스템은 카메라에 얼굴을 보여주는 것만으로 신원 확인이 가능하기 때문에 번거로운 신원 확인 과정을 거쳐야 하는 다른 시스템 구조에 비해 매우 편리한 기능을 제공할 수 있다.

• Proceedings of the Korean Environmental Health Society Conference
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• 2005.11a
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• pp.110-114
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• 2005

인공적으로 디젤류에 오염시킨 5kg의 토양이 충전된 두 개의 실험 column을 이용해서 외부 온도변화 효과를 최소화하기 위해서 $25^{\circ}C{\pm}2.5$로 유지시켰으며, 유량속도도 10ml/min로 일정하게 유지시켰다. 또한 수분은 활동범위 능력의 $60{\sim}80%$에서 유지시켰다. 따라서 연속식과 간헐 주입식 모드를 운전비용의 감소 및 효율의 향상 측면에서 모드의 평가를 위한 방법으로 이용기간 동안 총세균 수, 유류분해균 수의 변화, 탈수소효소 활성도의 변화 추이 분석을 하였다. 두 venting 모드별로 본 총 종속영양균 수와 유류분해균 수는 모두 대등한 성장률을 보였으며, 반응일 수에 따라 비교된 탈수소효소 활성도 반응 90일 동안 비슷한 활성을 유지 했다.