• 수산해양기술연구
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• 제25권3호
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• pp.137-142
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• 1989

본 논문에서는 연속시간계의 설계 문제에 있어, 연속계의 설계방법 그대로서는 설계 불가능한 하나의 문제, 즉, 복소좌반 평면상의 어떤 지정한 폐영역내의 극배치 문제를 쌍선형변환법을 이용해서 해결하는 하나의 설계방법을 제안했다. 실제적인 시스템 설계의 경우, 폐루우프 계의 특성근을 정확히 지정된 위치에 배치하여야만 할 경우는 드물고, 대개의 경우, 어떤 희망하는 영역내에 배치하면 충분하다. 특히 구체적으로 극을 지정하는 지침에 결핍되어 있을 경우나, 폐루우푸 계의 특성인 속응성, 진동특성, 안정도 등을 고려할 경우, 그 극을 지정 위치에 배치하기보다도 어떤 지정한 영역내에 배치하는 쪽이 유효하다고 할 수 있으므로, 다변수제어계의 설계 문제에 있어, 그 가치가 크다고 할 수 있다

• Smart Structures and Systems
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• 제20권5호
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• pp.525-537
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• 2017

This paper explores different vibration control strategies for the cancellation of human-induced vibration on a structure with time-varying modal parameters. The main motivation of this study is a lively urban stress-ribbon footbridge (Pedro $G\acute{o}mez$ Bosque, Valladolid, Spain) that, after a whole-year monitoring, several natural frequencies within the band of interest (normal paring frequency range) have been tracked. The most perceptible vibration mode of the structure at approximately 1.8 Hz changes up to 20%. In order to find a solution for this real case, this paper takes the annual modal parameter estimates (approx. 14000 estimations) of this mode and designs three control strategies: a) a tuned mass damper (TMD) tuned to the most-repeated modal properties of the aforementioned mode, b) two semi-active TMD strategies, one with an on-off control law for the TMD damping, and other with frequency and damping tuned by updating the damper force. All strategies have been carefully compared considering two structure models: a) only the aforementioned mode and b) all the other tracked modes. The results have been compared considering human-induced vibrations and have helped the authors on making a decision of the most advisable strategy to be practically implemented.

• Journal of the Optical Society of Korea
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• 제17권1호
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• pp.5-9
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• 2013

We report on high-power continuous-wave operations of an Er:YAG ceramic laser in-band pumped by a cladding-pumped Er,Yb fiber laser at 1532 nm. With an output coupler of 10% transmission, the ceramic laser yielded 16.7 W of continuous-wave output at 1645 nm for 28.8 W of incident pump power, corresponding to a slope efficiency of 61.0% with respect to the incident pump power. The lasing wavelength switched to 1617 nm when output couplers of > 20% transmission were used. Up to 16.2 W of 1617 nm output was generated for 33.0 W of incident pump power, corresponding to a slope efficiency of 51.8%. Graphene Q-switched operation of Er:YAG cermic laser at 1645 nm was also demonstrated with stable pulses of 30-74 kHz repetition rates and 1.5-6.4 ${\mu}s$ pulse widths.

• 한국환경과학회지
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• 제7권6호
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• pp.853-857
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• 1998

Purification of the isocitrate lyase extracted from Microbacterium laevaniformans was investigated. The isocitrate lyase was purified 43.6 folds by the following continuous treatment with ammonium sulfate fraction, DEAE-cellulose, DEAE-sephacel and Sephadex G-200 chromatography. The purified isocitrate lyase was showed to be a single protein band by polyacrylamide gel electrophoresis. The molecular weight of the purified isocitrate lyase was estimated 54,000 Da by the SDS-polyacrylamide gel electrophoresis. The Km and Vmax values for isocitrate were estimated to be 0.83mM and 0.33units/ml, respectively. Activity of isocitrate lyase was inhibited by cystein-HCl and glutathione.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 1999년도 추계종합학술대회 논문집
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• pp.309-312
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• 1999

Fiber Bragg gratings have many applications such as fiber sensors, band-stop filters, add-drop filters, and mode convertors. In this paper, we present the fabrication method of various fiber Bragg gratings by using continuous wave UV-Argon(frequency-doubled Argon) laser. In our experiments, hydrogenation of fibers was used to enhance photosensitivity of fiber. And we fabricated fiber gratings by the phase mask method.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2005년도 추계학술대회 논문집 전기물성,응용부문
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• pp.60-61
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• 2005

Electrodes were fabricated on a single ZnO nanowire by photolithography process, metal evaporation, and lift-off. The slow photoresponses of the ZnO nanowire under the continuous illumination of 325nm-wavelength light (corresponding to above-bandgap excitation) indicate that the traps related to oxygen vacancy disturb the flow of electron in ZnO nanowire. The photoresponse and PL spectra were measured, and observed that the excitonic band in the PL spectrum was absent in the photoresponse.

• 천문학회보
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• 제36권2호
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• pp.122.1-122.1
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• 2011

We propose a program of conducting research of young supernovae in nearby galaxies using the KMTNet facilities. Thanks to the wide field ($2^{\circ}{\times}2^{\circ}$) with multiple filters and the continuous sky coverage using the three 1.6 m telescopes, the KMTNet can provide an unprecedented opportunity for studying supernovae. The primary program is twofold: it can be used as a discovery facility of young supernovae and also as a facility providing multi-band photometric data of unprecedentedly high cadence for supernovae light curves.

• 한국음향학회지
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• 제42권1호
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• pp.25-31
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• 2023

능동소나를 이용하여 수중물체의 속도를 추정하려면 Continuous Wave(CW) 펄스를 이용하는 것이 일반적이나, 수중물체의 속도가 느리고 근거리의 해양에서는 잔향음의 영향으로 수중물체의 속도 추정이 용이하지 않다. 2017년도에 Wang 연구진은 이를 극복하고자 수중물체의 속도에 의한 도플러 변이에 둔감한 광대역 신호인 Hyperbolic Frequency Modulation(HFM) 펄스 두 개를 상반된 스윕방향으로 이용하였다. 두 펄스 간 송신 시간간격과 탐지시간 차이의 변화를 통하여 수중물체 속도 추정이 가능하다는 것을 시뮬레이션으로 제시하였다. 하지만 동일한 대역을 이용하므로 상호상관성에 의해서 수중물체 탐지 성능이 영향을 받을 수 밖에 없다. 상호상관성에 의한 수중물체 탐지 성능저하를 방지하기 위하여 대역이 분리된 상반된 스윕방향의 두 HFM 펄스 이용을 제안한다. 본 논문에서는 상반된 스윕방향의 두 대역 HFM을 이용하여 수중물체의 시선속도 추정에 관한 이론을 도출하였고, 펄스길이와 대역폭이 1 s와 400 Hz인 HFM 펄스로 시뮬레이션을 수행하였다. 제안한 방법을 이용하여 수중물체의 시선속도를 추정하면 약 6 %의 오차로 표적 속도 추정이 가능하다는 것을 시뮬레이션을 통하여 확인하였다.

• 패션비즈니스
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• 제21권4호
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• pp.105-115
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• 2017

Continuous lifting and carrying of babies constitutes a serious physical burden, leading to issues such as muscle fatigue and pain in child-care workers. However, there is a lack of research on the pressure and subjective comfort of baby carriers that are commercially available in the market. Therefore, this study was intended to determine the most comfortable and least burdensome type of baby carrier. This was done by analyzing muscle activity and pressure when subjects carried babies using three types of baby carriers. The types of baby carriers evaluated included a 'baby carrier of thin shoulder straps without back support band (X-type)', a 'baby carrier with a back-support band and without a hip sheet (H-type)', and a 'baby carrier with back support band and hip support (H-hip type). The subjective comfort of subjects wearing each type of baby carrier was investigated and compared to the objectively measured data. As a result, the X-type baby carrier showed the heaviest pressure on the shoulders and the subjective comfort was found to not be good. On the waist region, the H-type and H-hip type baby carriers showed significantly less muscle activation than the X-type baby carrier. However, subjects showed a stronger preference for the X-type baby carrier on the waist region, despite greater muscle activation. This appears to be because although the back-support band disperses the weight and thus improves physiological comfort; the wearers feel cramped and thus, lower their psychological comfort.

• 한국인터넷방송통신학회논문지
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• 제17권6호
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• pp.51-57
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• 2017

본 논문에서는 Ka 대역 소형 레이다용 주파수합성기를 제안하였다. 제작된 주파수합성기는 시스템에서 요구하는 다양한 파형을 생성하고 고속의 파형 및 주파수 전환을 위해 DDS를 적용하였다. 소형화를 위해 Ku 대역에는 MMIC를 최대한 적용하여 Ka 대역 회로를 소형 집적화 하였고 파형발생부 과 주파수 상향 변환부를 하나의 모듈로하여 설계 제작하였다. 제안된 주파수합성기는 선형 주파수 변조 파형과 위상변조 가능한 주파수 변조 연속 파형 등 발생이 가능하고, 대역폭 1GHz, 주파수 전환 속도 $0.191{\mu}sec$, 1 kHz 오프셋(offset)에서 -89.16 dBc/Hz의 위상잡음, 불요파 -50.9 dBc가 측정되었다.