• ETRI Journal
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• 제27권2호
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• pp.153-165
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• 2005

The main purpose of a spatial audio system is to give a listener the same impression as if he/she were present in a recorded environment. A dummy head microphone is generally used for such purposes. Because of its human-like shape, we can obtain good spatial sound images. However, its shape is a restriction on its public use and it is difficult to convert a 2-channel recording into multi-channel signals for an efficient rendering over a multi-speaker arrangement. In order to solve the problems mentioned above, a spatial audio system is proposed that uses multiple microphones on a rigid sphere. The system has five microphones placed on special points of the rigid sphere, and it generates audio signals for headphone, stereo, stereo dipole, 4-channel, and 5-channel reproduction environments. Subjective localization experiments show that front/back confusion, which is a common limitation of spatial audio systems using the dummy head microphone, can be reduced dramatically in 4-channel and 5-channel reproduction environments and can be reduced slightly in a headphone reproduction.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2007년도 추계학술대회 논문집
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• pp.250-254
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• 2007

As photovoltaic(PV) power generation systems become more common, it will be necessary to investigate islanding detection method for PV systems. Islanding of PV systems can cause a variety of problems and must be prevented. However, if the real and reactive powers of the load and PV system are closely matched, islanding detection by passive methods becomes difficult. Also, most active methods lose effectiveness when there are several PV systems feeding the same island. The active frequency drift positive feedback method(AFDPF) enables islanding detection by forcing the frequency of the voltage in the island to drift up or down. In this paper the research for the minimum value of chopping fraction gain applied digital phase-locked-loop (DPLL) to AFDPF considering output power quality and islanding prevention performance are performed by simulation and experiment according to IEEE Std 929-2000 islanding test.

• 터널과지하공간
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• 제21권6호
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• pp.439-449
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• 2011

터널의 페이스매핑(face mapping)을 신속하고 신뢰성 있게 수행하기 위하여 디지털 사진으로부터 3차원 좌표의 점군(point cloud)을 생성하고 이로부터 절리면의 방향과 간격 및 암질지수(R.Q.D), 절리면 거칠기 등을 분석하였다. 분석결과를 공학적 암반분류 방법인 RMR(Rock Mass Rating)과 Q 시스템에 입력하여 보강방법을 결정하고 터널을 시공하였다. 그 결과 터널 페이스매핑 작업의 안전성을 높이면서, 분석부터 보강작업까지의 시간을 절약하였다. 또 터널 막장면의 디지털 영상과 공학적 암반분류용 정보를 객관적으로 평가하고 필요 시재분석이 가능하도록 보존함으로써 보강등급 결정과 터널보강 방법의 신뢰도를 높였다.

• 설비공학논문집
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• 제17권3호
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• pp.201-208
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• 2005

This study presents the experimental study on improvement of frost/defrost performance in an heat pump system with newly developed fin and multiple compressors. As multiple compressors system, the variable and single speed compressor combinations has been introduced and compared with single speed 1-compressor system in a view point of improvement of frost/defrost performance. Also, newly developed corrugate shaped fin has been compared with conventional louver shaped fin. The frost/defrost performance is defined and some parameters are compared to discuss the effect of each combination. From this experimental study, it is known that if the variable and single speed compressor combination system equipped with corrugate shaped fin, the system performance has greatly improved not only for heating capacity, but also for frost performance.

• 한국컴퓨터정보학회논문지
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• 제22권5호
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• pp.41-49
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• 2017

Digital works such as computer programs, music, photographs, movies and dramas are copyrighted. Even if there were more than 1,000 violations per year for digital works, the punishment was very weak. Especially copyright infringement by teenager is increasing. This study aims to present the direction of future development through questionnaires on the perception and direction of college students about copyright. 157 college students were surveyed about copyright awareness, perception of detailed legal provisions, cost of monthly expenses, copyright violation, and direction of copyright protection. As a result of the questionnaire survey, awareness was high at 69%, but in detailed law was low at 17.2% and 22.3%. In the future direction of copyright policy, 72.6% of them answered that they should be "strengthened" and "more and more strengthened". In order to protect copyrights, enforcement of crackdowns, public relations activities, expansion of the legal market, and technical protection should be done. In order to do this, copyright-related education for elementary, middle, high school and college students are needed more and it is necessary to expand the legal market where high quality contents are traded. More research is needed on copyright protection technological methods.

• 정보보호학회논문지
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• 제28권4호
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• pp.839-845
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• 2018

빈번한 개인정보 유출 사고를 통해 프라이버시 정책이 강화됨에 따라 민감한 데이터는 암호화하여 저장한다. 이런 이유로 피조사자 소유의 암호화 된 데이터는 디지털 포렌식 관점에서 중요한 분석대상이다. 현재까지 디지털 증거수집 절차에서는 이미징만 고려하고 있으며, 하드웨어 고유 정보는 수집하지 않는다. 디스크 이미지에 남지 않는 정보를 통해 암호 키를 생성한다면 암호화 된 데이터를 복호화 할 수 없다. 최근 하드웨어 고유 정보를 이용하여 암호화를 수행하는 어플리케이션이 등장하였다. 따라서 본 논문에서는 보조기억장치에 남지 않는 하드웨어 고유 정보에 대해 연구하였으며, 하드웨어 고유 정보 수집 방안을 소개한다.

• 한국정보통신학회:학술대회논문집
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• 한국정보통신학회 2017년도 추계학술대회
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• pp.520-521
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• 2017

일반적인 카운터 타입의 시간-디지털 변환기에서 시간간격 신호와 클록신호의 비동기로 인하여 디지털 변환에러가 발생한다. 클록의 주기를 $T_{CLOCK}$라고 하면, 시간간격 신호의 시작신호와 클록의 비동기로 인하여 최대 $T_{CLOCK}$의 변환에러가 발생한다. 그리고 시간간격 신호의 멈춤신호와 클록의 비동기로 인하여 최대 $-T_{CLOCK}$의 변환에러가 발생한다. 그러나 시작신호와 클록을 동기화하고 클록을 시간간격 신호동안 발생시킬 경우 디지털 변환에러의 범위는 0에서 $(1/2)T_{CLOCK}$이다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2003년도 학술회의 논문집 정보 및 제어부문 B
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• pp.735-739
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• 2003

This paper presents a direct seek control algorithm for swing-arm type dual stage servo system that consists of a coarse actuator and a fine actuator. The proposed scheme is to design a control system that attenuates the effect of dynamic coupling between the two actuators so that the seek operation can be performed in a single-shot with stability. In an optical drive system with dual stage servo mechanism, the effect of dynamic coupling between the two actuators needs to be handled during the coarse seek operation due to its inherent structure. In an extreme case, the two actuators can collide each other, which leads to critical degradation of the seek performance. To handle this problem, our proposed control scheme is to generate the drive signals such that the two actuators behave as if they are a single fixed body. To this end, a feedforward controller and two feedback controllers are designed that enable the current drive system perform wide range of track seek. Simulation results are provided to show the validity and feasibility of our proposed algorithm.

• Archives of Reconstructive Microsurgery
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• 제7권1호
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• pp.10-14
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• 1998

When covering a skin defect of the finger with a local flap is difficult, a vascular island flap is often used. For a palmar skin defect, it is desirable to add a sensory supply to the flap. This report describes a neurovascular island flap that was used to repair a palmar skin defect, the donor skin coming from the dorsal region of the middle phalanx. This flap is elevated with a vascular pedicle of the palmar digital artery and its dorsal skin branch, including the dorsal digital veins, palmar digital nerve and its cutaneous branches. The advantage of this flap are that it can be transferred with ease and without any tension. No special manipulation is required under a microscope and operation can be performed under a simple nerve-block. There if little possibility that the flap itself undergoes ischemic change or congestion. The disadvantage of this flap are that a skin graft is required at the donor skin site and one palmar digital aretery is lost. We think that this neurovascular island flap is one of the useful methods for skin defects that are difficult to cover with a local flap.

• 보존과학회지
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• 제35권1호
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• pp.71-80
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• 2019

This study examined the applicability of digital technologies based on three-dimensional(3D) scanning, modeling, and printing to the restoration of damaged artifacts. First, 3D close-range scanning was utilized to make a high-resolution polygon mesh model of a roof-end tile with a missing part, and a 3D virtual restoration of the missing part was conducted using a haptic interface. Furthermore, the virtual restoration model was printed out with a 3D printer using the material extrusion method and a PLA filament. Then, the additive structure of the printed output with a scanning electron microscope was observed and its shape accuracy was analyzed through 3D deviation analysis. It was discovered that the 3D printing output of the missing part has high dimensional accuracy and layer thickness, thus fitting extremely well with the fracture surface of the original roof-end tile. The convergence of digital virtual restoration based on 3D scanning and 3D printing technology has helped in minimizing contact with the artifact and broadening the choice of restoration materials significantly. In the future, if the efficiency of the virtual restoration modeling process is improved and the material stability of the printed output for the purpose of restoration is sufficiently verified, the usability of 3D digital technologies in cultural heritage restoration will increase.