• International Journal of Internet, Broadcasting and Communication
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• 제13권3호
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• pp.118-123
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• 2021

Recently, digital crime is becoming more intelligent, and efficient digital forensic techniques are required to collect evidence for this. In the case of important files related to crime, a specific person may intentionally delete the file. In such a situation, data recovery is a very important procedure that can prove criminal charges. Although there are various methods to recover deleted files, we focuses on the recovery technique using HxD editor. When recovering a deleted file using the HxD editor, check the file structure and access the file data area through calculation. However, there is a possibility that errors such as arithmetic errors may occur when a file approach through calculation is used. Therefore, in this paper, we propose an algorithm that automatically calculates the header and footer of a file after checking the file signature in the root directory for efficient file recovery. If the algorithm proposed in this paper is used, it is expected that the error rate of arithmetic errors in the file recovery process can be reduced.

• 한국항해항만학회지
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• 제36권5호
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• pp.371-378
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• 2012

본 논문에서는 OQPSK(Offset Quadrature Phase Shift Keying) 변복조를 사용하는 수중음향통신에서 시간동기회복을 위해 기존의 Gardner TED(Timing Error Detector)에 Parabolic Peak Interpolation 을 사용하는 Peak Detector를 첨가하여 위상 수렴속도를 상승시켜 송신 데이터양의 감소를 도모하였다. Parabolic Peak Interpolation을 이용하여 지속적으로 국소 최대 또는 최소의 근사치로 이동한 후 Gardner TED를 적용하기 때문에 시간동기화 안정화를 속도를 빨리함으로써 Preamble 구간의 데이터양을 절반으로 줄일 수 있고 또한 Preamble 구간에서도 위상 수렴을 하지 못하는 임계치에서 제안한 방법을 시뮬레이션한 결과 임계점에서 BER(Bit Error Rate)이 약 23%정도 성능이 개선되는 것을 확인할 수 있었다. 또한 실제 동해에서 수집한 데이터를 사용하여 기존의 Gardner TED만 사용하는 방법과 성능 비교 결과 송수신기 사이의 거리가 3 km 이었을 때 제안한 방법을 적용한 경우 기존의 방법에 비해 Converge speed가 1.4배 이상 상승하는 것을 확인할 수 있었고, BER측면에서도 약 20%정도 상승하는 것을 확인할 수 있었다.

• ETRI Journal
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• 제28권4호
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• pp.435-443
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• 2006

This paper presents an efficient carrier recovery algorithm combined with a turbo-coding technique in a mobile communication system. By using a block turbo code made up of independently decodable block codes, we can efficiently recover the fast time-varying carrier phase as well as correct channel errors. Our simulation results reveal that the proposed scheme can accommodate mobiles with high speed, and at the same time can reduce the number of iterations to lock the phase.

• 한국원자력학회:학술대회논문집
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• 한국원자력학회 1995년도 추계학술발표회논문집(1)
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• pp.223-229
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• 1995

Loose Par Monitoring System(LPMS) is one of the fundamental diagnostic tools installed in the nuclear power plants. In this paper, recovery process algorithm and model for the corrupted impact signal generated by loose parts is presented. The characteristics of this algorithm can obtain a proper burst signal even though background noise is considerably high level comparing with actual impact signal. To verify performance of the proposed algorithm, we evaluate mathematically signal-to-noise ratio of primary output and noise. The performance of this recovery process algorithm is shown through computer simulation.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2004년도 ICEIC The International Conference on Electronics Informations and Communications
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• pp.1-4
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• 2004

We proposed a new type of timing recovery scheme to work with a system that uses BCJR (Bahl-Cocke-Jelinek-Raviv) decoding algorithm and BPSK modulation. The unknown timing offset is estimated by the modified Mueller and $M\ddot{u}ller$ estimator with the aid of the decoder. Timing offset can be acquired as soon as the symbols are received and be updated symbol by symbol. The simulation results for turbo codes whose decoder uses BCJR algorithm show a satisfactory performance even in case of severe timing jitter.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제9권12호
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• pp.5103-5115
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• 2015

In radar imaging, a target is usually consisted of a few strong scatterers which are sparsely distributed. In this paper, an improved sparse signal recovery algorithm based on smoothed l₀ (SL0) norm method is proposed to achieve high resolution ISAR imaging with limited pulse numbers. Firstly, one new smoothed function is proposed to approximate the l₀ norm to measure the sparsity. Then a single loop step is used instead of two loop layers in SL0 method which increases the searching density of variable parameter to ensure the recovery accuracy without increasing computation amount, the cost function is undated in every loop for the next loop until the termination is satisfied. Finally, the new set of solution is projected into the feasible set. Simulation results show that the proposed algorithm is superior to the several popular methods both in terms of the reconstruction performance and computation time. Real data ISAR imaging obtained by the proposed algorithm is competitive to several other methods.

• 한국의류학회지
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• 제45권2호
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• pp.335-345
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• 2021

The purpose of this study was to examine the effect of fabric movement on wrinkle recovery in a clothing care system and to propose an algorithm to improve wrinkle removal performance by adjusting fabric movements. With an increase in the reciprocating speed of the movement system, the number and amplitude of curves on the fabric also increased. This allowed the fabric to be applied to a larger tension, resulting in better wrinkle removal performance at higher speeds. However, even at high reciprocating speeds, wrinkles could not be removed effectively because of nodes at a few specific locations. Based on the results of fabric movement and wrinkle recovery, a complex movement algorithm was proposed with a mixture of various reciprocation speeds. It showed a 41%p (24%→65%) improvement of wrinkle recovery when compared with the conventional algorithm that showed simple fabric movement at 180 rpm. This was because the positions of nodes and antinodes changed continuously and the force by the reciprocating motion could be applied evenly to the fabric.

• 정보처리학회논문지C
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• 제9C권4호
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• pp.589-596
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• 2002

이동호스트에서의 데이터 전송 서비스로는 대역폭의 부담을 줄이고 신뢰성 있는 에러 복구를 위하여 원본 데이터를 그룹화하여 오류 복구 패리티를 생성한 후 손실이 발생하였을 경우에 오류 복구 패리티를 재전송하는 FEC 방식과 재전송 폭주를 막을 수 있는 지역복구 방식이 적합하다. FEC 방식과 SERVER기반의 지역복구 방식 두 가지의 병행은 신뢰성 있는 멀티캐스트를 가능하게 한다. 본 논문은 MH가 송신자인 경우와 수신자인 경우로 나누어서 이동호스트에서의 삼각라우팅, 터널집중성 문제 해결을 통하여, FEC방식과 SERVER 기반의 지역복구 방식의 병합으로 손실을 복구하는 알고리즘을 제안하였다. 이 알고리즘의 손실 모델은 동종 독립 손실, 이종 독립 손실, 상호 의존적 손실 모델로 성능 평가를 하였다. 제안된 알고리즘은 이동호스트에서 데이터의 양과 수신자의 수가 많은 환경에서 효율적임을 확인하였다.

• 한국정보과학회논문지:정보통신
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• 제31권3호
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• pp.314-326
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• 2004

블루투스는 휴대폰을 비롯한 디지털 디바이스간의 탄력적이고 확장성 있는 무선 ad-hoc 네트워크를 제공할 수 있는 기술로 가능성을 인정받아왔다. 이러한 네트워크가 지원되기 위해서는 블루투스 스캐터넷(Scatternet)은 필수적인 요소이다. 그러므로 블루투스 스캐터넷과 관련되어서 현재까지 다양한 방법론이 제시되고 있다. 하지만 기존의 연구들은 시뮬레이션을 통한 방법론을 제시하는데 그치는 경우가 대부분이며, 스캐터넷의 탄력성과 확장성을 확보하지 못하고 그 복잡성으로 인해 하드웨어 구현에 제약이 있는 경우들이 많다. 본 논문에서는 실제 하드웨어 구현이 용이하고, 스캐터넷의 탄력성과 확장성을 확보할 수 있는 노드 링 스캐터넷(Node Ring Scatternet:NRS) 알고리즘을 제안하였다. 이 알고리즘은 초기 형성과 재형성 부분으로 구성이 되어 있다. 초기 형성과 관련되어 제한적 SEEK/SCAN 알고리즘을 제안하였고, 재형성과 관련되어서는 DIAC 알고리즘과 예약 복구 노드(Reserved Recovery Node) 알고리즘을 제안하였다. 또 실제 시스템 상에서 스캐터넷 알고리즘을 운용하기 위한 SFMP(Scatternet Formation & Management Protocol)을 설계하고, 상용 블루투스 하드웨어로 구현을 하여 20개의 디바이스까지의 스캐터넷 실험을 수행하였다. 실험 결과 기존의 유사 알고리즘에 비해 스캐터넷 형성 시간과 그 확률이 높은 결과를 얻었다.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제10권3호
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• pp.976-995
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• 2016

Workflow scheduling is one of the challenging problems in cloud computing, especially when service reliability is considered. To improve cloud service reliability, fault tolerance techniques such as fault recovery can be employed. Practically, fault recovery has impact on the performance of workflow scheduling. Such impact deserves detailed research. Only few research works on workflow scheduling consider fault recovery and its impact. In this paper, we investigate the problem of workflow scheduling in clouds, considering the probability that cloud resources may fail during execution. We formulate this problem as a multi-objective optimization model. The first optimization objective is to minimize the overall completion time and the second one is to minimize the overall execution cost. Based on the proposed optimization model, we develop a heuristic-based algorithm called Min-min based time and cost tradeoff (MTCT). We perform extensive simulations with four different real world scientific workflows to verify the validity of the proposed model and evaluate the performance of our algorithm. The results show that, as expected, fault recovery has significant impact on the two performance criteria, and the proposed MTCT algorithm is useful for real life workflow scheduling when both of the two optimization objectives are considered.