• Restorative Dentistry and Endodontics
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• 제43권2호
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• pp.22.1-22.9
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• 2018

Objectives: To evaluate and compare light-transmittance in dental tissues and dental composite restorations using the incremental double-layer technique with varying layer thickness. Materials and Methods: B1-colored natural teeth slabs were compared to dental restoration build-ups with A2D and B1E-colored nanofilled, supra-nanofilled, microfilled, and microhybrid composites. The enamel layer varied from 0.3, 0.5, or 1.2 mm thick, and the dentin layer was varied to provide a standardized 3.7 mm overall sample thickness (n = 10). All increments were light-cured to $16J/cm^2$ with a multi-wave LED (Valo, Ultradent). Using a spectrophotometer, the samples were irradiated by an RGB laser beam. A voltmeter recorded the light output signal to calculate the light-transmittance through the specimens. The data were analyzed using 1-way analysis of variance followed by the post hoc Tukey's test (p = 0.05). Results: Mean light-transmittance observed at thicker final layers of enamel were significantly lower than those observed at thinner final layers. Within 1.2 mm final enamel resin layer (FERL) thickness, all composites were similar to the dental tissues, with exception of the nanofilled composite. However, within 0.5 mm FERL thickness, only the suprananofilled composite showed no difference from the dental tissues. Within 0.3 mm FERL thickness, none of the composites were similar to the dental tissues. Conclusions: The supra-nanofilled composite had the most similar light-transmittance pattern when compared to the natural teeth. However, for other composites, thicker FERL have a greater chance to match the light-transmittance of natural dental tissues.

• 한국통신학회논문지
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• 제41권9호
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• pp.1108-1119
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• 2016

본 논문에서는 스마트폰의 저주파 대역 누설 전자파가 미치는 악영향을 분석하기 위해 스마트폰 모델별로 기본 동작에 따라 누설되는 30 MHz 이하의 누설 전자파 신호의 스펙트럼 특성 및 방사 패턴을 분석하였다. 사용자와의 직접적인 인터페이스를 담당하는 스마트폰의 입출력 센서 모듈(터치스크린, 카메라, 마이크 및 스피커 모듈)을 활성화시키는 4가지 기본 동작 모드에 의해 누설되는 전자파 신호를 상용 Near-Field 마그네틱 프로브를 통해 1cm의 격자 간격으로 정밀하게 측정하였다. 측정된 누설 전자파 신호를 분석한 결과, 스마트폰의 모델 및 동작 모드별로 누설되는 저주파 대역 전자파는 특이한 피크(Peak) 또는 하모닉(Harmonic) 피크 성분을 보이며, 동작 모드에 따라 각각의 입출력 센서 모듈이 활성화될 경우 해당 센서 모듈 및 메인보드 상의 AP(Application Processor), 메모리 주위로 상대적으로 강한 저주파 대역의 전자파가 누설되는 것을 확인할 수 있었다.

• 정보처리학회논문지:컴퓨터 및 통신 시스템
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• 제1권3호
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• pp.219-228
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• 2012

무선 인터넷 서비스가 활성화 되면서 현재 많은 사용자들은 공간에 제약 없이 다양한 인터넷 서비스들을 사용할 수 있게 되었다. 그러나 기존의 모바일 노드의 이동성 보장을 위한 IETF의 MIP, PMIP 등과 같은 이동성 관리 기법들은 모바일 노드에 무거운 프로토콜 스택을 탑재하게 하거나 LMA, MAG 등과 같은 신규 구성 요소 추가 등의 문제점을 안고 있다. 이를 위해 본 논문에서는 PMIPv6에서의 위치관리기법과 Fast Handover 기법을 제안하였다. 위치관리기법은 노드의 이동패턴에 따라 페이징 영역을 동적으로 조정하도록 제안하였고, Fast Handover 기법은 MIH 기술을 적용하여 이 기종 네트워크간의 핸드오버 신호 처리 시간을 단축하였다. 이를 평가하기위해 노드가 이동하는 환경에서의 위치관리비용과 핸드오버 지연시간을 계산하였고, 제안기법이 PMIPv6보다 최소 29%, 최대 83% 더 효율적으로 평가되었다.

• 조명전기설비학회논문지
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• 제20권6호
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• pp.55-62
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• 2006

본 논문에서는 3상 유도전동기의 고장진단을 수행하기 위해 패턴인식에 기반을 둔 진단 알고리즘을 제안한다. 실험 장치는 유도전동기 구동의 기계적 모듈과 고장신호를 구하기 위한 데이터 획득 모듈로 구성하였다. 진단 절차를 위한 첫 번째 단계로서 전처리 과정은 획득한 전류를 단순화하고 정규화 하는 것을 수행한다. 데이터의 단순화 과정은 3상전류를 Concrodia 벡터의 크기로 변환하는 것을 적용한다. 다음으로 특징 추출 단계를 커널 주성분 분석과 선형판별분석으로 수행하며, 마지막으로, 분류기는 방사기저함수 네트워크를 사용한다. 다양한 부하에 대하여 몇몇의 전기적 고장과 기계적 고장 하에서 획득한 데이터를 이용하여 제안된 방법의 타당성을 검증한다.

• 한국군사과학기술학회지
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• 제17권1호
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• pp.90-95
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• 2014

The system design and the system performance analysis of 3D imaging laser radar system for the mapping purpose is addressed in this article. For the mapping, a push-bloom scanning method is utilized. The pulsed fiber laser with high pulse energy and high pulse repetition rate is used for the light source of laser radar system. The high sensitive linear mode InGaAs avalanche photo-diode is used for the laser receiver module. The time-of-flight of laser pulse from the laser to the receiver is calculated by using high speed FPGA based signal processing board. To reduce the walk error of laser pulse regardless of the intensity differences between pulses, the time of flight is measured from peak to peak of laser pulses. To get 3D image with a single pixel detector, Risley scanner which stirs the laser beam in an ellipsoidal pattern is used. The system laser energy budget characteristics is modeled using LADAR equation, from which the system performances such as the pulse detection probability, false alarm and etc. are analyzed and predicted. The test results of the system performances are acquired and compared with the predicted system performance. According to test results, all the system requirements are satisfied. The 3D image which was acquired by using the laser radar system is also presented in this article.

• 한국정보과학회논문지:소프트웨어및응용
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• 제27권1호
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• pp.24-32
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• 2000

인간의 생각만으로 기계를 작동할 수 있게 하는 인터페이스 시스템에 관한 연구 분야인 BCI (Brain-Computer Interface)에서는 피험자의 두피로부터 EEG(Electroencephalograph)를 측정하고 인식하여 뇌 상태를 알아내고 그 결과를 기계의 조종에 응용하는 방법을 사용한다. 본 연구에서는 각 개인으로부터 고유의 뇌파인 EEG를 얻고 신호처리하여 인식하는 인식모델을 제안하였다. 제안된 모델은 특정 작업을 수행하고 있을 때의 EEG 신호로부터 인식에 중요한 영향을 미치는 특징들을 추출해 내고, 이를 인식에 이용한다. 제안된 모델은 인식할 EEG 패턴들을 두개씩 분류하여 각각을 인식한 후, 그 결과를 종합하여 최종적인 인식결과를 얻도록 하였다. 본 연구의 실험에서는 피험자가 4가지의 작업을 수행하는 동안 얻어지는 4가지 EEG 패턴을 인식하였다. 제안된 모델은 90%이상의 높은 인식율을 보였고, 각 피험자에게 독특하게 존재하는 특징들을 인식 결과로서 제공하였다. 제안된 모델의 높은 인식율과 빠른 처리속도는 실시간 BCI 시스템에 응용될 수 있는 가능성을 보여주고 있다.

• 한국정밀공학회지
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• 제27권6호
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• pp.82-89
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• 2010

Ankle-foot orthosis with an artificial pneumatic muscle which is intended for the assistance of plantarfelxion torque was developed. In this study, power pattern of the device in the various pneumatics and the effectiveness of the system were investigated. The pneumatic power was provided by ankle-foot orthosis controlled by user‘s physiological signal, that is, muscular stiffness in soleus muscle. This pneumatic power can assist plantarflexion torque of ankle joint. The subjects performed maximal voluntary isokinetic plantarflexion motion on a biodexdynamometer in different pneumatics, and they completed three conditions: 1) without wearing the orthosis, 2) wearing the orthosis with artificial muscles turned off, 3) wearing the orthosis activated under muscular stiffness control. Through these experiments, we confirmed the effectiveness of the orthosis and muscular stiffness control using the analyzing isokinetic plantarflexion torque. The experimental results showed that isokinetic torques of plantarflexion motion of the ankle joints gradually increased in incremental pneumatic. The effectiveness of the orthosis was -7.26% and the effectiveness of the muscular stiffness control was 17.83% in normalized isokinetic plantarflexion torque. Subjects generated the less isokinetic torques of the ankle joints in wearing the orthosis with artificial muscles turned off, but isokinetic torques were appropriately reinforced in condition of wearing the orthosis activated under muscular stiffness control(17.83%) compared to wearing the orthosis(-7.26%). Therefore, we respect that developed powered orthosis is applied in the elderly that has weak muscular power as the rehabilitation equipment.

• 한국가금학회지
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• 제27권2호
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• pp.155-161
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• 2000

Unfortunately, there is no technique which is stable and repetitive to produce transgenic chicken, although various ways of gene transfer including PGC-and embryonic cell-mediated gene transfer, DNA microinjection, virus inoculation and sperm cells have been employed. The aims of this study were 세 develop and establish such a stable, repetitive and efficient way of gene transfer giving a faithful gene expression during development after the reconstruction of embryo in an UV-irradiated egg. A dual reporter plasmid (pJJ9), a fusion gene containing lacZ and GFP driven by a CMV promoter was used to exploit either merits of both reporting markers. lacZ with strong signal or GFP with vital marking. Electroporated embryonic blastodermal cells (EBCs) in the presence of the pJJ9 DNA faithfully showed 377 bp PCR product and lacZ or GFP expressions in the identical cells in vitro of in vivo. Furthermore, analyses of expression pattern of the foreign DNA demonstrated that microinjected EBCs cells into the UV-irradiated recipient egg should participate in normal developmental process, for example, proliferation and differentiation into various tissues. Thirty percentages of the manipulated eggs showed lacZ expression in their tissues. These results together with the specific procedures used in this study should facilitate avian transgenesis.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제9권10호
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• pp.4002-4014
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• 2015

ITU-R M.1842-1, as a well-known specification dedicated to maritime mobile applications, has standardized wireless transmission protocols according to the particular characteristics of a maritime communications scenario. A time division multiple access (TDMA) frame structure, along with modulation schemes to achieve a high data rate, has been described clearly in ITU-R M.1842-1. However, several specification items are still under "to be decided" status, which brings ambiguity to research works. In addition, the current version of ITU-R M.1842-1 is focused mainly on maritime transmissions in open-sea areas, where the cyclic prefix (CP) is set to zero and only 16-QAM is used in the multi-carrier (MC) system. System performance might be dramatically degraded in coastline areas due to the inter-symbol interference (ISI) caused by selective fading. This is because there is a higher probability that the signal will be reflected by obstacles in coastline areas. In this paper, we introduce the transmission resource block (TRB) dedicated to ITU-R M.1842-1 for a ship ad-hoc network (SANET), where the pilot pattern of TRB is based on the terrestrial trunked radio (TETRA). After that, we evaluated SANET performance under the maritime channel model in a coastline area. In order to avoid noise amplification and to overcome the ISI caused by selective fading, several strategies are suggested and compared in the channel estimation and equalization procedures, where the link-level simulation results finally validate our proposals.

• 수산해양기술연구
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• 제46권2호
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• pp.173-183
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• 2010

In a split beam echo sounder, the transducer design needs to have minimal side lobes because the angular position and level of the side lobes establishes the usable signal level and phase angle limits for determining target strength. In order to suppress effectively the generation of unwanted side lobes in the directivity pattern of split beam transducer, the spacing and size of the transducer elements need to be controlled less than half of a wavelength. With this purpose, a 50 kHz tonpilz type transducer with a half-wavelength diameter in relation to the development of a split beam transducer was designed using the equivalent circuit model, and the underwater performance characteristics were measured and analyzed. From the in-air and in-water impedance responses, the measured value of the electro-acoustic conversion efficiency for the designed transducer was 51.6%. A maximum transmitting voltage response (TVR) value of 172.25dB re $1{\mu}Pa/V$ at 1m was achieved at 52.92kHz with a specially designed matching network and the quality factor was 10.3 with the transmitting bandwidth of 5.14kHz. A maximum receiving sensitivity (SRT) of -183.57dB re $1V/{\mu}Pa$ was measured at 51.45kHz and the receiving bandwidth at -3dB was 1.71kHz. These results suggest that the designed tonpilz type transducer can be effectively used in the development of a split beam transducer for a 50kHz fish sizing echo sounder.