• Proceedings of the Korean Society of Precision Engineering Conference
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• 1997.04a
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• pp.491-495
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• 1997

In this paper, an effective mount design method using vector synthesis is presented for two mount systems. For designing mount stiffnesses effectively, we perform a sensitivity analysis, i.e, identify the contribution rate of an input component vector to the total output vector. Especially, we show that it is necessary to takea phase sensitivity into consideration in case of two mount systems, such as the excavator mount systems having engine mounts and cabin mounts. THe proposed method is testified is testified through an test bed.

• Journal of Satellite, Information and Communications
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• v.6 no.1
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• pp.45-49
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• 2011

In this paper, we present the high resolution and low phase noise frequency synthesizer for satellite terminal. To improve the phase noise of frequency synthesizer, we analyze how the configuration of frequency synthesizer affect the phase noise. The implemented frequency synthesizer reduce the phase noise and show the high resolution. The output power of this frequency synthesizer is over -2dBm in 950~1450MHz and the phase noise of the -101dBc/Hz at 10kHz frequency offset.

• Proceedings of the Optical Society of Korea Conference
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• 2000.02a
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• pp.120-121
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• 2000

Michelson 간섭계에 결맞음광을 입사시킬 때와 비고전광인 수 상태광을 입사시켰을 때의 위상감도에 대하여 이론적으로 계산하여 비교하였다. 수 상태광이 입사하는 경우라도 고전광인 결맞음광에서의 한계를 능가할 수 없음을 보였으며, 두 경우 모두 위상차의 불확정도 $\Delta$$ heta$는 1/(equation omitted) (N은 광자수)에 비례하였다. 또한 사용하는 광검출기의 양자효율에 따라 $\Delta$$\theta$가 어떤 영향을 받는지 분석하였다. (중략)

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2011.07a
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• pp.204-207
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• 2011

본 논문에서는 3DTV 의 입체감 향상을 위한 3D 음향의 원근감 재현 기술을 제안한다. 먼저, 3D 영상 객체의 깊이를 추출하고 영상 객체의 깊이에 따라 오디오 객체의 거리감을 조절한다. 오디오 거리감 재현을 위해 필요한 오디오 깊이 인자는 3D 영상의 좌/우 이미지의 차이 정보로부터 오디오에 맞도록 비선형 변환을 통해 구해진다. 3D 오디오 재현 알고리즘은 기존의 서라운드 입체음향 기술과 원근감 재현 기술로 구성된다. 원근감 재현 기술은 추정된 오디오 깊이 인자에 따라 신호크기, 초기 반사음, 근거리 머리전달함수, 위상 제어를 통해서 구현된다. 특히, 3D 영상 객체가 화면 앞으로 튀어 나올 때 소리도 튀어나오도록 함으로써 3D 영상 객체와 연동되는 입체 음향을 효과를 통해 3D 방송 시청 시 오디오/비디오 입체감을 향상시켜준다. 상용화된 3DTV 를 활용하여 음질 평가 전문가들의 주관 청취 평가를 통해 제안한 원근감 재현 기술이 3D 방송 시청에 적합함을 검증한다.

• The Journal of the Korea Contents Association
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• v.2 no.1
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• pp.32-38
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• 2002

In the AV system, stereophonic system has been studied to produce a realistic sound effect. The width of stereo AV system speakers is narrow, to have the spatial impression of sound effect, widening the sound image is necessary. The direction of sound image depends on the phase delay and the sound pressure level difference between two channels. In this paper, we analyze the relationship between the phase delay and the direction of the sound image relating to the frequency of sound source. Also we experimented to directionally localize the sound image of the pure tone with shifting phases and controling sound pressure love between two channels when the sound is reproduced by two speakers to make a spatial impression of sound effect.

• Journal of the Korean Society for Precision Engineering
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• v.28 no.5
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• pp.585-590
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• 2011

Accelerometers have been exploited widely in various fields from monitoring vibration of precision machines to detecting an earthquake wave. The precision calibration of the accelerometers is required to maintain the measurement reliability when measuring the vibration of objects with accelerometers for modal analysis. Among evaluation factors for determining sensitivity of accelerometers, phase delay term should be also considered for accurate calibration. In this paper, a new calibration system of accelerometers capable of measuring phase delay as well as magnitude of its sensitivity was proposed and realized in the frequency range of 20 Hz to 5 kHz.

• Proceedings of the Korean Information Science Society Conference
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• 2001.10c
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• pp.430-432
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• 2001

IPv6은 IPv4가 업그레이드 된 것으로서 기하급수적으로 늘어나는 인터넷 주소를 감당하고, IPv4의 단점을 보안하는 새로운 인터넷 프로토콜이다. IPv6은 plug-and-plug방식으로 이웃 발견 프로토콜을 사용하여 현재 네트워크의 위상 및 링크의 상태를 측정하여 스스로 주소를 자동 설정 할 수 있다. 또한 IPv4와는 달리 멀티캐스팅 기능을 기본으로 제공하고 있으며 이를 지원 하는 응용을 필요로 하기 때문에 본 논문에서는 멀티캐스트에서 가장 널리 사용되는 화이트 보드를 IPv6에서 동작하도록 설계 구현 한다.

• Proceedings of the CALSEC Conference
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• 1999.07a
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• pp.165-173
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• 1999

인터넷의 보급과 국제화의 확산으로 영자 인터넷신문의 활용방안에 대한 연구가 활발하게 이루어지고 있다 인터넷 신문이 기존 활자 신문의 보조매체의 한계를 뛰어넘어 독립매체로서의 위상을 확보해 감에 따라 인터넷의 특성을 살린 영자인터넷 신문의 제작 전략이 절실히 요구되고 있는 실정이다. 국내에서 서비스되고 있는 영자 인터넷 신문의 현황을 파악하고 영자 인터넷 신문의 특징과 장단점을 분석하여 영자 인터넷 신문의 제작방향을 제시한다. 또한 현재 영자 인터넷 신문의 부가서비스와 컨텐츠를 기반으로 부가서비스의 다양화와 컨텐츠의 지식기반화를 통하여 국내 컨텐츠의 국외 접근성에 대한 정성적인 분석을 실시하였다. 국내에서 만들어지는 영어 컨텐츠라는 장점을 최대한 활용하여 외국인에 대한 국내 포탈 사이트로의 확대 전략과 온라인 상거래 기반의 영문종합쇼핑몰 구성방안을 제시한다.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.26 no.5
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• pp.492-498
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• 2015

As the integration of circuit components increases steadily, various EMS(Electromagnetic Susceptibility) problems have emerged from integrated circuits and electrical systems. The electromagnetic susceptibility of VCOs(Voltage Controlled Oscillator) is especially critical in RF systems. Therefore, in this paper, through the phase noise theory that models electrical oscillators as linear time variant systems, the EMS characteristics of representative VCO -ring VCO and LC VCO- with 1.2 GHz of reference oscillating frequency are analyzed under the existence of the electromagnetic noise coupled in power supply. An simulation algorithm is developed to extract impulse response function based on the phase noise theory. When there is no supply noise, the magnitude of the jitter of two oscillators were similar to around 2.1 ps, but in presence of supply noise, the jitter was significantly lower in LC VCOs than ring VCOs.

• Sleep Medicine and Psychophysiology
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• v.9 no.1
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• pp.41-47
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• 2002

Objectives: In a number of simulated night shift studies, timed exposure to bright light improves sleep quality and work performance. We evaluated the effect of bright light on adaptation to night shift work with a field study. Methods: Five female nurses working shifts at Korea University Hospital were recruited for participation in this study. We investigated two series of six consecutive shift rotations comprising three day and three night shifts, using wrist Actigraphy, the Stanford Sleepiness Scale, Visual-analogue scales, STIM and tympanic membrane temperature for daytime sleep quality, alertness, subjective feeling, attention performance, and temperature rhythm. The subjects were exposed to bright light (2,500 lux) from 24:00 to 04:00 a.m. on three consecutive night shifts during the second series, whereas they worked under normal lightening (650 lux) conditions during the first series. Results: Actigraphic assessment of daytime sleep showed no significant difference between the first and third night shift in both baseline and light exposure phase. The mean lowest temperature shifted earlier during baseline phase but not during the light exposure phase. Also, the score for subjective feelings of depression, anxiety, physical discomfort and sleepiness was significantly higher in the third night shift than the first during baseline phase but not during the light exposure phase. Attention and attention switching ability was significantly improved in the third night shift compared to the first night during the light exposure phase but there were no significant changes during the baseline phase. Conclusion: This result suggests that there were no significant differences between the two phases in measures of quality of daytime sleep, but subjective feelings, attention and alertness were enhanced during light exposure. Although some placebo effects and learning effects might influence this result, bright light exposure between midnight and 4:00 a.m. may improve adaptation to night shift. In future, further controlled studies with a larger sample size, including melatonin measurement, are needed for real shift workers.