• 디지털콘텐츠학회 논문지
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• 제9권4호
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• pp.533-541
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• 2008

분산 모바일 시스템에서 혼잡제어와 끊김 문제 해결은 주요한 관심사로 떠오르고 있다. 본 논문에서는 분산 모바일 트랜잭션을 지원하는 시스템의 성능 개선을 위해 그룹화 기반의 퍼지 참조 스트리밍 기법을 이용한다. 이 기법은 모바일 클라이언트에서 제기된 트랜잭션 요청문제를 GS인터페이스를 이용하여 해결하도록 한다. 그리고 끊김 문제를 해결하기 위해 트랜잭션 읽기/갱신기법을 이용하여 스트리밍 서비스를 효율적으로 수행하도록 한다. 실험 평가 결과 제안된 기법이 다른 기법보다 효율적임을 보인다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2004년도 추계학술대회 논문집 전기기기 및 에너지변환시스템부문
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• pp.224-226
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• 2004

Digital Kalman filter is presented as a powerful approach to obtain the reference estimation of the control current for shunt active power filter. This algorithm provides the best estimate of the fundamental and harmonic frequency components from the sampled values of the line current or voltage. By adopting of the digital Kalman filtering algorithm, the structure of the control algorithm eliminates the need of a Phase locked loop(PLL) for the synchronization of the reference signal used in the compensation and it not sensitive to the distortion of the line voltage. The effectiveness of the algorithm is confirmed by the computer simulations.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2004년도 추계학술대회 논문집
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• pp.1480-1485
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• 2004

In this paper, a real-time digital kalman filtering algorithm is used to obtain the reference estimation of the control current for shunt active power filter. This algorithm provides the best estimate of the fundamental and harmonic frequency components from the sampled values of the line current or voltage waveform. By adopting of the digital Kalman filtering algorithm, the structure of the control algorithm eliminates the need of a Phase locked loop(PLL) for the synchronization of the reference signal used in the compensation and it not sensitive to the distortion of the line voltage. The effectiveness of the algorithm is confirmed by the computer simulations.

• 지식경영연구
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• 제19권4호
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• pp.149-170
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• 2018

Healthcare lifelog, a personal record relating to disease treatment and healthcare, plays an important role in healthcare paradigm shifts in which medical and information technology converge. Healthcare services based on various healthcare lifelogs are being launched domestically by both large corporations and small and medium enterprises, however, they are being built on an individual platform that is dependent on each company. Therefore, the terms of lifelog data are different as well as the measurement specifications are not uniform. This study proposes a reference model for minimum common data required for sharing and utilization of healthcare lifelog. Literature study and expert survey derived 3 domain, 17 essential items, and 51 sub-items. The model provides definition, measurement data format, measurement method, and precautions for each detailed measurement item, and provides necessary guidelines for data and service design and construction for healthcare service. This study has its significance as a basic research supporting the activation of ecosystem by ensuring interoperability of data between heterogeneous healthcare devices linked to digital healthcare platform.

• 한국통신학회논문지
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• 제31권9C호
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• pp.905-913
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• 2006

펄스 방식(Impulse radio)의 초광대역(Ultra-Wideband) 시스템의 타이밍 동기과정에서 획득/추적 과정이 이상적으로 수행되더라도 잔여 타이밍 오차는 존재하게 된다. 이러한 잔여 타이밍 오차는 시스템의 성능에 큰 영향을 미치게 된다. 본 논문에서는 상관 검출 수신기에서 미세 타이밍 오차를 보상하기 위해 보조신호(Reference signal)를 이용한 디지털 위상고정 루프(Digital Phase-Locked Loop)를 제시한다. 우선, 미세 타이밍 오차에 의한 비트에러률(Bit Error Rate:BER)의 성능 열화를 고찰한 후, 타이밍 추적기를 사용함으로써 타이밍 오차가 보상되는 과정과 보상 후 BER 성능을 제시한다. 그리고 타이밍 검출기는 보조신호와 수신신호간의 상관을 이용하는 방식이 제안되었으며 샘플링 주기는 프레임 단위로 이루어지도록 설계되었다. 또한, 본 논문은 성능비교를 위해 여러 종류의 가우시안 모노사이클 펄스에 대해 성능 평가를 수행한다.

• 전기학회논문지
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• 제65권4호
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• pp.659-665
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• 2016

In this paper, we propose a novel position accuracy enhancement method of a low-end GPS using digital map information. The latest digital map has various kinds of information on geographical features. The proposed method uses position information of lane marks among the geographical features. We define the position information of lane marks as the reference points. The position information of a low-end GPS acquired for a period of time is defined as the source points. In the proposed method, rotation and translation matrices between the reference and the source points are calculated by using an Iterative Closest Point(ICP) algorithm. The source points are transformed by the obtained rotation and translation matrices. Finally, the transformed source points are projected on the reference points. Through these processes, the position accuracy of a low-end GPS is ultimately enhanced. To verify the proposed method, the various real experimental results are presented.

• 한국정보통신학회논문지
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• 제18권10호
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• pp.2345-2350
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• 2014

본 논문에서는 포트 임피던스가 75옴인 실내 디지털 TV (DTV)용 안테나의 특성 측정 방법에 대해 소개하였다. 일반적인 RF (혹은 마이크로파) 시스템과 측정 장비의 기준 임피던스는 거의 대부분 50옴이다. 이에 비해 실내 디지털 TV용 안테나의 기준 임피던스는 75옴이므로 기준 임피던스가 50옴인 측정 장비를 이용하여 직접 특성을 측정할 수 없다. 50옴을 기준으로 하는 장비를 이용하여 75옴에 적합하도록 설계된 안테나의 특성(임피던스, 복사패턴 및 이득)에 대한 측정방법을 소개하였다.

• 전기학회논문지
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• 제56권8호
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• pp.1484-1490
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• 2007

The Cross Reference Point(CRP) is a robust method for finding salient points in watermarking systems because it is based on the geometrical structure of a normalized image in order to avoid pointing error caused by digital attacks. After normalization of an image, the 100 CRPs are calculated. Next, the 100 blocks centered by CRPS are formed. These 100 blocks are arranged using a secrete key. Each boundary of 50 out of 100 blocks is surrounded by 8 blocks which are selected by the ordered number of a preceding block. This number is a seed of random number generator for selecting 8 out of 50 blocks. The search area of a center block is formed by a secrete key. The pixels of a center block are quantized to 10 levels by predefined thresholds. The watermarks are generated by the 50 quantized center blocks. These watermarks are embedded directly in the remaining 50 blocks. In other words, 50 out of 100 blocks are utilized to generate watermarks and the remaining 50 blocks are used to watermark embedding. Because the watermarks are generated in the given images, we can successfully detect watermarks after several digital attacks. The reason is that the blocks for the generation and detection of watermarks are equally affected by digital attacks except for the case of local distortion such as cropping.

• 한국정보통신학회:학술대회논문집
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• 한국정보통신학회 2014년도 춘계학술대회
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• pp.45-46
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• 2014

본 논문에서는 포트 임피던스가 75옴인 실내 디지털 TV (DTV)용 안테나의 특성 측정 방법에 대해 소개하였다. 일반적인 RF (혹은 마이크로파) 시스템과 측정장비의 기준 임피던스는 거의 대부분 50옴이다. 이에 비해 실내 디지털 TV용 안테나의 기준 임피던스는 75옴이므로 기준 임피던스가 50옴인 측정 장비를 이용하여 직접 특성을 측정할 수 없다. 50옴을 기준으로 하는 장비를 이용하여 75옴에 적합하도록 설계된 안테나의 특성(임피던스, 복사패턴 및 이득)을 측정방법에 대해 소개하였다.

• Current Optics and Photonics
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• 제7권6호
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• pp.673-682
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• 2023

In this paper, a three-key triple data encryption algorithm (TDEA) of a digital cryptosystem based on phase-shifting interferometry is proposed. The encryption for plaintext and the decryption for the ciphertext of a complex digital hologram are performed by three independent keys called a wavelength key k₁(λ), a reference distance key k₂(d_r) and a holographic encryption key k₃(x, y), which are represented in the reference beam path of phase-shifting interferometry. The results of numerical simulations show that the minimum wavelength spacing between the neighboring independent wavelength keys is about δλ = 0.007 nm, and the minimum distance between the neighboring reference distance keys is about δd_r = 50 nm. For the proposed three-key TDEA, choosing the deviation of the key k₁(λ) as δλ = 0.4 nm and the deviation of the key k₂(d_r) as δd_r = 500 nm allows the number of independent keys k₁(λ) and k₂(d_r) to be calculated as N(k₁) = 80 for a range of 1,530-1,562 nm and N(d_r) = 20,000 for a range of 35-45 mm, respectively. The proposed method provides the feasibility of independent keys with many degrees of freedom, and then these flexible independent keys can provide the cryptosystem with very high security.