• 대한전기학회:학술대회논문집
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• 대한전기학회 2004년도 학술대회 논문집 전문대학교육위원
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• pp.49-51
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• 2004

This paper researched the power loss characteristics according to winding method of high frequency transformer. Power loss was analyzed by PExprt using FEM software. The ferrite core model for analysis be used the EE type. Transformer model objected type applied to flyback converter. Therefore, analysis result was obtained the many parameter of DC, AC resistance, leakage inductance, copper loss, core loss, and temperature etc.

• 정보저장시스템학회논문집
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• 제6권2호
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• pp.57-62
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• 2010

This paper measured and analyzed the source of total power loss of an ODD of a notebook computer. It shows that the biggest power loss is the windage loss due to the friction between rotating disk and surrounding air. It measured the power loss by the tilting motion of a rotating disc which is originated from the unbalanced mass of the rotating disc or the squareness between case-rotor and shaft. The power loss of rotating disc due to tilting motion was also calculated by using FLUENT, and it was correlated with the measured one. This paper shows that the one of the effective methods to reduce the power loss of an ODD is to reduce the tilting motion of a rotating disc.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제12권7호
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• pp.3150-3171
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• 2018

In this paper, a heuristic method that leverages packet traces captured at the entire boarder of an ISP to distinguish and estimate the overall packet loss within an ISP's management domain (Intra_Path_Loss) and that in the outside Internet (Inter_Path_Loss) is proposed. Our method is inspired by that packet losses happened at different locations will cause different TCP sequence number patterns at the border of an ISP. Thereby, we leverage these TCP sequence number patterns to build a series of heuristic rules to estimate Intra_Path_Loss and Inter_Path_Loss, respectively. We do this work with an eye towards showing that the overall packet losses defined and estimated in this paper can provide the operators with some valuable information to help them precisely grasp the overall performance of network paths and narrow down the range of network anomalies. The proposed method is rigorously validated with simulations, and finally the results from a regional academic network JSERNET verify its effectiveness and practicability.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제13권9호
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• pp.4572-4586
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• 2019

Mobile Edge Computing (MEC) and Information-Centric Networking (ICN) are essential network architectures for the future Internet. The advantages of MEC and ICN such as computation and storage capabilities at the edge of the network, in-network caching and named-data communication paradigm can greatly improve the quality of video streaming applications. However, the packet loss in wireless network environments still affects the video streaming performance and the existing loss recovery approaches in ICN does not exploit the capabilities of MEC. This paper proposes a Deep Learning based Loss Recovery Mechanism (DL-LRM) for video streaming over MEC based ICN. Different with existing approaches, the Forward Error Correction (FEC) packets are generated at the edge of the network, which dramatically reduces the workload of core network and backhaul. By monitoring network states, our proposed DL-LRM controls the FEC request rate by deep reinforcement learning algorithm. Considering the characteristics of video streaming and MEC, in this paper we develop content caching detection and fast retransmission algorithm to effectively utilize resources of MEC. Experimental results demonstrate that the DL-LRM is able to adaptively adjust and control the FEC request rate and achieve better video quality than the existing approaches.

• 전기학회논문지
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• 제65권8호
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• pp.1326-1333
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• 2016

It is important to clear the fault and prevent resulting in damage to power system. Although the frequency of generator internal fault is relatively low, it can lead to incalculable damage to power system as well as generator. Especially, loss of field on generator can cause the generator to lose synchronism for a short time if it is not removed promptly. Therefore, it is needed to conduct research on loss of field relay for detecting or clearing the loss of field. However, the setting of the relay may vary in generator operator or engineer, and the relay is not coordinated well with other elements associated with loss of field. In this paper, we address specifically the coordination of positive offset mho loss of field relay which is one of the protection schemes for loss of field. Computer simulations are performed by using ElectroMagnetic Transients Program-Restructured Version (EMTP-RV) based on actual data.

• 정보보호학회논문지
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• 제27권1호
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• pp.129-145
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• 2017

본 연구는 지속적으로 발생하고 있는 개인정보 유출사고에 대한 기업의 리스크와 손해금액 산출을 위해, 최신 리스크 분석방법론인 FAIR(Factor Analysis of Information Risk)를 사용하였다. FAIR를 통해서 실제 개인정보 유출 사고 기업을 예를들어, 손해금액을 분석하고 산출하는 방법론을 제시 하였다. 전문가 집단의 설문을 실시하고 AHP(Analytic Hierarchy Process) 방법론을 사용하여 손해금액 산정요소의 중요도와 적절성을 객관적으로 평가하였다, 본 연구를 통해서 개인정보보호 실무 담당자는 스스로 손해금액을 최신 리스크 평가 방법론을 통해서 산정하고 입증할 수 있다. 또한 본 연구의 손해금액 산정요소를 해당기업에 맞게 선택하여 정확한 개인정보 유출에 따른 손해금액 등 경제적 손실을 추정할 수 있으며, 사고조치 및 예방대책의 수립과 경영진에게 보고할 수 있는 객관적인 근거를 확보 할 수 있다.

• 한국정보통신학회:학술대회논문집
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• 한국해양정보통신학회 2009년도 춘계학술대회
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• pp.657-660
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• 2009

영상 보간법은 다양한 영상 처리를 위하여 사용되는 기반 기술로서, 보간 과정에서 발생하는 화질열화를 최소화하기 위한 연구가 활발히 진행되고 있다. 본 논문에서는 손실 정보 추정을 이용하여 개선된 양선형 보간법을 제안한다. 제안하는 방법에서는 획득된 저해상도 영상의 다운 샘플링 및 보간을 통하여 저해상도 영상 생성시 발생하는 손실 정보를 추정하고, 추정한 손실 정보를 고해상도로 보간된 영상에 적용하여 화질 열화를 최소화한다. 동일한 영상을 이용한 실험을 통해서 기존 방법들 보다 0.97~1.79dB의 PSNR이 향상된 것을 알 수 있었고, 윤곽선을 비롯한 주관적 화질 향상을 역시 확인하였다. 제안하는 방법은 영상 해상도 개선과 영상 복원을 위한 다양한 응용 환경에서 유용하게 사용될 수 있다.

• 한국콘텐츠학회논문지
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• 제9권11호
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• pp.18-26
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• 2009

영상 해상도 향상 알고리즘은 영상 확대 및 영상 복원을 위한 기반 기술로 사용되며, 해상도 향상 과정에서 문제점은 흐려짐 현상이나 블록 현상으로 인한 화질 열화의 발생이다. 본 논문에서는 하위 레벨 보간을 이용한 손실 정보 추정과 영상 해상도 향상 기법을 제안한다. 제안하는 방법에서는 획득한 저해상도 영상의 다운샘플링-보간 과정을 이용해서 손실 정보를 계산하고, 손실 정보의 보간을 통해서 손실 정보를 추정하며, 가중치 계수와 결합한 추정 손실 정보를 고해상도로 보간 된 영상에 적용한다. 동일한 영상을 이용한 실험 결과, 제안한 방법이 기존의 방법들보다 PSNR에서 평균 2.3dB 이상 향상된 것을 검증하였고, 윤곽선 및 문자의 인식 정도에 대한 주관적인 화질 비교 결과도 개선되었음을 확인하였다. 제안한 방법은 영상 개선을 필요로 하는 다양한 비디오 응용 분야에서 유용하게 사용될 수 있다.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제15권7호
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• pp.2339-2355
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• 2021

In this paper, a joint probabilistic data association algorithm based on loss function (LJPDA) is proposed so that the computation load and accuracy of the multi-target tracking algorithm can be guaranteed simultaneously. Firstly, data association is divided in to three cases based on the relationship among validation gates and the number of measurements in the overlapping area for validation gates. Also the contribution coefficient is employed for evaluating the contribution of a measurement to a target, and the loss function, which reflects the cost of the new proposed data association algorithm, is defined. Moreover, the equation set of optimal contribution coefficient is given by minimizing the loss function, and the optimal contribution coefficient can be attained by using the Newton-Raphson method. In this way, the weighted value of each target can be achieved, and the data association among measurements and tracks can be realized. Finally, we compare performances of LJPDA proposed and joint probabilistic data association (JPDA) algorithm via numerical simulations, and much attention is paid on real-time performance and estimation error. Theoretical analysis and experimental results reveal that the LJPDA algorithm proposed exhibits small estimation error and low computation complexity.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제7권10호
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• pp.2338-2356
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• 2013

In cognitive radio networks, acquiring the position information of the primary user is critical to the communication of the secondary user. Localization of primary users can help improve the efficiency with which the spectrum is reused, because the information can be used to avoid harmful interference to the network while simultaneity is exploited to improve the spectrum utilization. Despite its inherent inaccuracy, received signal strength based on range has been used as the standard tool for distance measurements in the location detection process. Most previous works have employed the path-loss propagation model with a fixed value of the path loss exponent. However, in actual environments, the path loss exponent for each channel is different. Moreover, due to the complexity of the radio channel, when the number of channel increases, a larger number of RSS measurements are needed, and this results in additional energy consumption. In this paper, to overcome this problem, we propose using the Bayesian compressive sensing method with a calibrated path loss exponent to improve the performance of the PU localization method.