• Title/Summary/Keyword: Recovery analysis

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Frame Rearrangement Method by Time Information Remarked on Recovered Image (복원된 영상에 표기된 시간 정보에 의한 프레임 재정렬 기법)

  • Kim, Yong Jin;Lee, Jung Hwan;Byun, Jun Seok;Park, Nam In
    • Journal of Korea Multimedia Society
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    • v.24 no.12
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    • pp.1641-1652
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    • 2021
  • To analyze the crime scene, the role of digital evidence such as CCTV and black box is very important. Such digital evidence is often damaged due to device defects or intentional deletion. In this case, the deleted video can be restored by well-known techniques like the frame-based recovery method. Especially, the data such as the video can be generally fragmented and saved in the case of the memory used almost fully. If the fragmented video were recovered in units of images, the sequence of the recovered images may not be continuous. In this paper, we proposed a new video restoration method to match the sequence of recovered images. First, the images are recovered through a frame-based recovery technique. Then, after analyzing the time information marked on the images, the time information was extracted and recognized via optical character recognition (OCR). Finally, the recovered images are rearranged based on the time information obtained by OCR. For performance evaluation, we evaluate the recovery rate of our proposed video restoration method. As a result, it was shown that the recovery rate for the fragmented video was recovered from a minimum of about 47% to a maximum of 98%.

A Comparative Study on Factor Recovery of Principal Component Analysis and Common Factor Analysis (주성분분석과 공통요인분석에 대한 비교연구: 요인구조 복원 관점에서)

  • Jung, Sunho;Seo, Sangyun
    • The Korean Journal of Applied Statistics
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    • v.26 no.6
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    • pp.933-942
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    • 2013
  • Common factor analysis and principal component analysis represent two technically distinctive approaches to exploratory factor analysis. Much of the psychometric literature recommends the use of common factor analysis instead of principal component analysis. Nonetheless, factor analysts use principal component analysis more frequently because they believe that principal component analysis could yield (relatively) less accurate estimates of factor loadings compared to common factor analysis but most often produce similar pattern of factor loadings, leading to essentially the same factor interpretations. A simulation study is conducted to evaluate the relative performance of these two approaches in terms of factor pattern recovery under different experimental conditions of sample size, overdetermination, and communality.The results show that principal component analysis performs better in factor recovery with small sample sizes (below 200). It was further shown that this tendency is more prominent when there are a small number of variables per factor. The present results are of practical use for factor analysts in the field of marketing and the social sciences.

Threats Analysis and Mobile Key Recovery for Internet of Things (IoT 환경에서의 보안위협 분석과 모바일 키 복구)

  • Lee, Yunjung;Park, Yongjoon;Kim, Chul Soo;Lee, Bongkyu
    • Journal of Korea Multimedia Society
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    • v.19 no.5
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    • pp.918-923
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    • 2016
  • IoT should be considered security risk environments such as various platforms and services including smart devices that can be mounted on household electric appliances, healthcare, car, and heterogeneous networks that are connected to the Internet, cloud services and mobile Apps.. In this paper, we provide analysis of new security threats, caused by open-platform of IoT and sensors via the Internet. Also, we present the key recovery mechanism that is applied to IoT. It results to have compatibility with given research, reduces network overhead, and performs key recovery without depending on key escrow agencies or authorized party.

Analysis on the Performance Test Results of Heat Pump for the Closed Cooling Water Heat Recovery on Combined Thermal Power Plant (복합화력발전소의 냉각수 배열회수를 위한 히트펌프의 성능평가)

  • Lee, Sung-Ho
    • The KSFM Journal of Fluid Machinery
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    • v.19 no.2
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    • pp.43-48
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    • 2016
  • This study proves successes of Energy Service Company (ESCO) business by heat pump performance test. The purpose of ESCO business is recover investment costs through saving energy from installation of energy reduction facility. The most important technology assessment items are heat recovery and generator output. Experimental result shows that increase quality of heat recovery (11.52Gcal/h), while decrease generator output (0.234kw). In its final analysis, the ESCO business is successful according to our data.

Analysis on Current Limiting and Recovery Characteristics of a SFCL using Magnetic Coupling of Two Coils with Series Connection (직렬연결된 두 코일의 자기결합을 이용한 초전도 전류제한기의 전류제한 및 회복특성 분석)

  • Lim, Sung-Hun;Kim, Jin-Seok;Ahn, Jae-Min;Moon, Jong-Fil;Kim, Jae-Chul
    • Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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    • 2008.10a
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    • pp.281-283
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    • 2008
  • The superconducting fault current limiter (SFCL) using magnetic coupling of two coils with series connection, which was suggested by us, has the merit to increase the operational current and the limiting impedance of the SFCL through the adjustment of the inductance ratio and the winding direction of two coils. In addition, the recovery characteristics of the SFCL is affected by the winding direction of two coils as well as two coils' inductance ratio. In this paper, the fault current limiting and recovery characteristics of a SFCL using magnetic coupling of two coils with series connection were analyzed. Through the analysis based on the experimental results, the recovery characteristics and the current limiting characteristics of the SFCL were confirmed to be improved more in case of the additive polarity winding.

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An Analysis of Recloser Operation According to Recovery Characteristics of Superconducting Fault Current Limiter (초전도 한류기의 회복특성에 따른 재폐로 동작 분석)

  • Rhee, Sang-Bong;Kim, Chul-Hwan;Kim, Kyu-Ho;Kim, Jae-Chul;Hyun, Ok-Bae
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.58 no.5
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    • pp.905-910
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    • 2009
  • For proper application and operation of a SFCL(Superconducting Fault Current Limiter) in distribution systems, the prior investigation of fundamental characteristics and its effects analysis to the systems are very important. A point of view in coordination with recloser in distribution systems, characteristic about quenching and recovering of SFCL should be studied. Especially, its detailed study of recovery characteristic is particularly important to avoid conflict between the SFCL and the recloser. In this paper, the resistive type SFCL and recloser, which used in distribution system, were implemented using EMTP/ATPDraw and MODELS language. To analyze the recovery characteristics of SFCL according to recloser operation in distribution systems, case studies have been simulated and investigated.

Elastic-plastic Contact Stress Analysis of CRT Glass Bulb (CRT 글래스 벌브의 탄소성 접촉 응력 해석)

  • Kang, Dae Jin;Shin, Woon Seo;Song, Chang Seop
    • Journal of the Korean Society for Precision Engineering
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    • v.14 no.2
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    • pp.145-151
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    • 1997
  • In this paper, we discuss the cathode ray tube(CRT) glass bulb stress and sagging recovery by the contact band pressure using finite element method. We analyzed the band pressure and stress using contact element method between band and bulb before and after banding process which was conducted to decrease the stress concentration using finite element method, and calculated sagging recovery. The analysis results were confirmed by experiments using strain gauge and sagging recovery test apparatus.

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Analysis of Thermal Recovery Characteristics for Nozzle of SF6 GCB Considering Nozzle Ablation (노즐용삭을 고려한 SF6 가스차단기 노즐의 열적회복특성 해석)

  • Lee Byeong-Yoon;Song Ki-Dong;Chong Jin-Kyo;Park Kyong-Yop
    • The Transactions of the Korean Institute of Electrical Engineers C
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    • v.54 no.2
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    • pp.76-82
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    • 2005
  • In this paper, a method for analyzing the thermal recovery characteristics of the nozzle of gas circuit breaker was described. In order to obtain thermal recovery characteristics, the transient simulation of SF6 arc plasma within the nozzle was carried out. In particular, the nozzle ablation was taken into account by simultaneously solving the PTFE concentration equation with the governing equations such as continuity, momentum and energy equation. After that, post arc current calculation was performed with the rate of rise of recovery voltage changed. From the calculated post arc current, it was possible to suggest the thermal recovery characteristics of the nozzle of gas circuit breaker.

Quantitative Analysis of Elastic Recovery Behavior after Bending of Ultra High Strength Steel Sheet: Spring-back or Spring-go (유한요소법을 이용한 초고강도 판재 굽힘에 따른 후변형의 정량적 분석: Spring-back or Spring-go)

  • Kwak, E.J.;Lee, K.;Suh, C.H.;Lim, Y.H.
    • Transactions of Materials Processing
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    • v.20 no.6
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    • pp.456-460
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    • 2011
  • A major source of difficulty in die design for high strength steel is the high level of elastic recovery during unloading. The degree of elastic recovery is affected by factors such as material strength, bending angle, punch's corner radius and sheet thickness. Finite Element Method was used in the present work to quantitatively analyze the elastic recovery for various combinations of these parameters. In some cases elastic recovery happened in reverse direction. This phenomenon, which we call spring-go, was explained via changes in stress distribution in the panel occurring in the forming process.

A Scalable Recovery Tree Construction Scheme Considering Spatial Locality of Packet Loss

  • Baek, Jin-Suk;Paris, Jehan-Francois
    • KSII Transactions on Internet and Information Systems (TIIS)
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    • v.2 no.2
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    • pp.82-102
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    • 2008
  • Packet losses tend to occur during short error bursts separated by long periods of relatively error-free transmission. There is also a significant spatial correlation in loss among the receiver nodes in a multicast session. To recover packet transmission errors at the transport layer, tree-based protocols construct a logical tree for error recovery before data transmission is started. The current tree construction scheme does not scale well because it overloads the sender node. We propose a scalable recovery tree construction scheme considering these properties. Unlike the existing tree construction schemes, our scheme distributes some tasks normally handled by the sender node to specific nodes acting as repair node distributors. It also allows receiver nodes to adaptively re-select their repair node when they experience unacceptable error recovery delay. Simulation results show that our scheme constructs the logical tree with reduced message and time overhead. Our analysis also indicates that it provides fast error recovery, since it can reduce the number of additional retransmissions from its upstream repair nodes or sender node.