• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.38 no.6
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• pp.537-546
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• 2010

This research work contributed to a study for the procedure and methodology to assess the fatigue durability for a composite torque link of helicopter landing gear, which was newly developed and fabricated by the resin transfer moulding technique to interchange with metal component. The simulated load spectrum anticipated to be applied to the torque link during its operation life was generated using an advanced method of probabilistic random process, and the fatigue durability was evaluated by the strength degradation approach on the basis of material test data. The full scale fatigue test was also performed and compared with the analysis results.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.34 no.12B
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• pp.1426-1434
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• 2009

RFID/USN is considered as a key convergence technology in future ubiquitous network. In RFID/USN, the power saving issue receives a great attention due to limited battery lifetime of sensor node. In this paper, we propose a new power saving algorithm, which takes advantage of long-term sleep period. To provide a full network connectivity and balance the battery consumption among sensor nodes, the proposed algorithm intelligently selects the long-term sleep sensor nodes. With mathematical analysis and simulations, we prove that the proposed algorithm can significantly reduce the power consumption of sensor nodes as compared to existing algorithms.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.28 no.7
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• pp.580-583
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• 2017

To compensate the degraded SAR image due to the residual errors and the spatial variant errors remaining after the motion compensation in the airborne SAR, we have introduced the autofocus method based on the partition processing. Thus, after we perform the spatial partition for the spotlight SAR data and the time partition for the stripmap SAR data, we reconstruct the subpatch images for the partitioned data. Then, we perform the local autofocus with the suitability analysis process for the phase errors estimated by the autofocus. Moreover, if the estimated phase errors are not properly compensated for the subpatch images, we perform the phase compensation method with the weight to the estimated phase error close to the degraded subpatch image to increase the SAR image quality.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2008.02a
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• pp.103-106
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• 2008

물리 메모리 영역에는 증거로 활용될 수 있는 프로세스 정보와 이름, ID, 비밀 번호, 전자 메일 주소 등의 정보를 담고 있다. 또 용의자가 행위를 감추기 위해 안티 포렌식 기법을 사용하여 저장매체 상에서 완전 삭제한 파일의 잔여 데이터를 취득할 수 있는 가능성이 있다. 하드 디스크와 같은 저장 매체의 경우 증거 수집 절차시 Hash와 같은 무결성 보장 과정을 거쳐 복사본의 유효성 확인이 가능하지만 물리 메모리 영역의 경우 운용 중인 시스템에서 발생하는 운영체제와 응용 프로그램의 동작에 의한 지속적인 데이터의 변화로 무결성 및 동일한 대상에서 수집되었다는 것을 확인하기 어렵고 소프트웨어 기반의 수집은 시스템의 상태를 변화 시킨다. 본 논문에서는 물리 메모리 영역 수집 기법을 알아보고 IEEE1394의 특성을 이용한 하드웨어 기반 물리 메모리 영역 수집 도구를 구현하였다. 또 수집된 물리 메모리 덤프를 이용하여 물리 메모리에서 얻을 수 있는 정보를 확인하고 동일 대상의 메모리와 다른 대상의 메모리를 비교하여 그 차이를 확인한다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.34 no.2B
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• pp.119-129
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• 2009

According to the advent of the ubiquitous environment, not only a location based service at the outside but also a location based service at the inside was more increased socially. Accordingly, this paper proposes the efficient determination system to locate a object in frequent change of indoor environment. Proposing system in this paper introduce the NLOS identification and mitigation to resolve NLOS problem, using this way that corrects location data as RWA and KF apply to result data can improve accuracy of a object. At last we are going to compare and analyze existing typical triangulation with proposed indoor location determination system to demonstrate algorithm efficiency for proposed indoor location determination system.

• Proceedings of the Korean Information Science Society Conference
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• 2006.06b
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• pp.376-378
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• 2006

본 논문에서는 소동물 양전자방출단층촬영 영상(Positron Emission Tomography, PET) 내 종양영역을 자동분할하고 분할된 윤곽선주변의 기하학적 위험구간에 따른 종양의 형태특성을 분석하기 위한 방법을 제시한다. PET 영상내 검출된 종양영역의 신뢰성을 위해 위음성(False negative, FN) 및 위양성(False positive, FP)의 위험구간을 같이 제공하는 것이 필요하다. 따라서, 방사선 특이적 특성이 반영된 명암값을 기반으로 Fuzzy C-Means(FCM) 클러스터링을 수행하여 종양영역을 자동 분할한다. 분활된 종양영역의 위험구간은 클러스터 간 공유되는 영역의 소속값을 이용하여 위음성, 위양성을 계산한다. 또한, 임의의 소속값 임계치 변화를 통해 위험구간의 변화에 따른 종양의 형태적 특성변화를 관측한다. 이러한 지역적 변화의 관측을 통해 위험구간의 형태학적 위치를 판단할 수 있어 위험구간에 따른 추가적인 잔여 암의 위치 및 형태 파악을 용이하게 한다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.39B no.10
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• pp.691-699
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• 2014

In order to increase network lifetime, duty-cycle MAC protocols which can reduce energy consumption caused by idle listening is proposed for WSNs. In common duty-cycle MAC protocols, each sensor node calculates its duty-cycle interval based on the current amount of residual energy. However, in WSNs with the capability of energy harvesting, existing duty-cycle intervals based on the residual energy may cause the sensor nodes which have high energy harvesting rate to suffer unnecessary sleep latency. Therefore, a duty-cycle scheduling scheme which adjust the duty-cycle interval based on both of the residual energy and the energy harvesting rate was proposed in our previous work. However, since this duty-cycle MAC protocol overlooked the performance variation according to the change of duty-cycle interval and adjusted the duty-cycle interval only linearly, the optimal duty-cycle interval could not be obtained to meet application requirements. In this paper, we propose three methods which calculate the duty-cycle interval and analyse their results. Through simulation study, we verify that network lifetime, end-to-end delay and packet delivery ratio can be improved up to 23%, 44% and 31% as compared to the existing linear duty-cycle scheduling method, respectively.

• Journal of Korea Technology Innovation Society
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• v.12 no.1
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• pp.212-236
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• 2009

This study is an attempt to deduct environmental uncertainties facing next-generation convergence services, in four areas including customer, technology, service provider and regulation. We assess the level of residual uncertainty with regard to key environmental uncertainty factors, and conduct a scenario planning analysis. Based on the results of this analysis, we provide suggestions on market entry strategy for providers of this next-generation convergence service. The strategic assessment of six scenarios developed in this study, each with two levels of residual uncertainty (alternate futures and a range of futures) resulted in two key success factors (KSF), namely, customer demand trends and easing of advertising restrictions. Four types of strategic scenarios were then discerned, for each of which we present response capabilities that may be required of service providers, along with strategic suggestions. The results of this study are rich in implications for both policy-makers and regulators seeking ways to create and stimulate a convergence service market and prospective providers of next-generation convergence services, as they provide concrete tips related to market entry strategy, including efficient resource allocation, types of market entry and time-frames for entry.

• The Journal of Korean Institute of Information Technology
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• v.16 no.11
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• pp.69-76
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• 2018

As for V2I(Vehicle-to-Infrastructure) systems with energy-constrained RSUs(Road Side Units), the previous data delivery strategies have not considered the aspect of energy usage at RSUs. A new data delivery strategy has been proposed to determine the RSU's participation in data delivery based on the probability dependent on the RSU's remaining energy, and it showed the lower data delivery time than the previous approaches. In this paper, we propose methods to analyze the number of RSUs participating in data delivery and the variations of RSUs' energy value for the consecutive data deliveries. As a numerical result, compared with the previous strategy, the probability-based data delivery strategy shows the lower number of participating RSUs and the increased average energy value of all RSUs. In addition, from the analytical results, we propose considerations for the real implementations of the similar systems.

• Journal of Korea Multimedia Society
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• v.15 no.4
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• pp.485-491
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• 2012

This paper proposes 'Coding Unit Tree' based on quadtree efficiently with motion vector to represent splitting information of a Coding Unit (CU) in HEVC. The new international video coding, High Efficiency Video Coding (HEVC), adopts various techniques and new unit concept: CU, Prediction Unit (PU), and Transform Unit (TU). The basic coding unit, CU is larger than macroblock of H.264/AVC and it splits to process image-based quadtree with a hierarchical structure. However, in case that there are complex motions in CU, the more signaling bits with motion information need to be transmitted. This structure provides a flexibility and a base for a optimization, but there are overhead about splitting information. This paper analyzes those signals and proposes a new algorithm which removes those redundancy. The proposed algorithm utilizes a type code, a dominant value, and residue values at a node in quadtree to remove the addition bits. Type code represents a structure of an image tree and the two values represent a node value. The results show that the proposed algorithm gains 13.6% bit-rate reduction over the HM-1.0.