• 한국통신학회논문지
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• 제25권1B호
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• pp.42-47
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• 2000

버스트 모드 패킷 트래픽 조건에서 스위칭 소광비를 최대화하는 전기 광학 광변조기의 바이어스 안정화를 위한 새로운 방법을 입증하였다. 광변조기의 오프 레벨 출력 전력을 샘플링하고 최소화함으로써 패킷 트래픽 밀도의 변화에 무관하게 높은 소광비를 갖는 광 게이트로서 동작한다

• 한국공작기계학회:학술대회논문집
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• 한국공작기계학회 2004년도 추계학술대회 논문집
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• pp.388-392
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• 2004

Due to the lack of stiffness and difficulties of control, it is hard to achieve well balanced magnetic levitation. In this paper, we analysis the current and position stiffness change according to bias current through experiment. Then, compensation equations were presented. After obtaining PD gain for each bias current and PD gain region through levitation experiment, we consider the characteristics.

• 제어로봇시스템학회논문지
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• 제21권2호
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• pp.168-172
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• 2015

In general, open-loop fiber-optic gyroscopes (FOG) are less stable than closed-loop FOGs but they offer simpler implementation. The typical operation time of line-of-sight (LOS) stabilization systems is a few seconds to one hour. In this paper, a open-loop fiber optic gyroscope (FOG) for LOS applications is designed and implemented. The design goal is aimed at implementing a low cost, compact FOG with low Angle Random Walk (ARW) (< $0.03deg/\sqrt{h}$) and bias instability (< 0.25deg/h). The FOG uses an open-loop all-fiber configuration with 100M PM fiber wound on a small diameter spool. In order to get the design goal, digital signal processing techniques for signal detection, modulation control and compensation are designed and implemented in FPGA.

• International Journal of Aeronautical and Space Sciences
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• 제3권2호
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• pp.13-23
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• 2002

In this paper, we present a sliding mode control strategy for the re-orientation maneuver of rigid spacecraft containing rotating wheels. The wheels are considered as internal devices, and external inputs are employed for generation of control commands. The formulation is developed for a general case while particular example is applied to pitch bias momentum spacecraft with a single momentum wheel. The resultant control commands are used to take the gyroscopic effects into account which are caused by the rotating wheels. The controller designed demonstrates that the nutational motion of the pitch bias momentum spacecraft is effectively controlled. It is also assumed that the external control torque device is of on-off nature, and pulse width modulation technique is applied to construct proper control torque history.

• Journal of Dental Anesthesia and Pain Medicine
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• 제21권3호
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• pp.183-205
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• 2021

This systematic review and meta-analysis aimed to analyze the effectiveness of maxillary stabilization splint (SS) therapy to reduce headache (HA) intensity and HA frequency in patients with temporomandibular disorders (TMD)-HA comorbidity. Randomized controlled trials (RCTs) using full-arch coverage, hard resin, and maxillary SS therapy were included. Electronic databases, including Cochrane Library, MEDLINE through PubMed, Web of Science, and EMBASE, were searched. The risk of bias was analyzed based on Cochrane's handbook. The search yielded 247 references up to January 28, 2020. Nine RCTs were included at a high risk of bias. The comparison groups included other splints, counseling, jaw exercises, medications, neurologic treatment, and occlusal equilibration. Four studies reported a statistically significant reduction in HA intensity, and five studies reported significant improvement in HA frequency from baseline at 2-12 months in patients with TMD-HA comorbidity treated with a full-arch hard maxillary SS. HA frequency in tension-type HA (TTH) comorbid with TMD diagnoses of myofascial pain (MFP) or capsulitis/synovitis improved significantly with SS than that with full-arch maxillary non-occluding splint (NOS) in two studies. Comparison groups receiving hard partial-arch maxillary splint nociceptive trigeminal inhibition (NTI) showed statistically significant improvements in HA intensity in patients with mixed TMD phenotypes of MFP and disc displacement comorbid with "general HA." Comparison groups receiving partial-arch maxillary resilient/soft splint (Relax) showed significant improvements in both HA intensity and frequency in patients with HA concomitant with MFP. The meta-analysis showed no statistically significant difference in the improvement of pain intensity at 2-3 months with comparison of the splints (partial-arch soft [Relax], hard [NTI], and full-arch NOS) or splint use compliance at 6-12 months with comparison of the splints (partial-arch Relax and full-arch NOS) versus the SS groups in patients with various TMD-HA comorbidities. In conclusion, although SS therapy showed a statistically significant decrease in HA intensity and HA frequency when reported, the evidence quality was low due to the high bias risk and small sample size. Therefore, further studies are required.

• Journal of applied mathematics & informatics
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• 제9권2호
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• pp.869-877
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• 2002

In the presence of unit nonresponse we perform the calibration estimation procedure for the population total corresponding to the levels of auxiliary information and derive the Taylor and the Jackknife variance estimators of it. We study the nonresponse bias reduction and the variance stabilization, and then show the efficiency of the Taylor and the Jackknife variance estimators by simulation study.

• 한국정보통신학회:학술대회논문집
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• 한국정보통신학회 2014년도 추계학술대회
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• pp.569-572
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• 2014

본 논문에서는 MEMS 용량형 센서를 위한 CMOS 스위치드-커패시터 인터페이스 회로를 설계하였다. 설계된 회로는 커패시턴스-전압 변환기(CVC), 2차 스위치드 커패시터 ${\Sigma}{\Delta}$ 변조기 및 비교기로 구성되어있다. 또한 일정한 바이어스를 공급해주는 바이어스 회로를 추가하였다. 전체적인 회로의 저주파 잡음과 오프셋을 감소시키기 위하여 Correlated-Double-Sampling(CDS) 기법과 Chopper-Stabilization(CHS) 기법을 적용하였다. 설계 결과 CVC는 20.53mV/fF의 민감도와 0.036%의 비선형성특성을 보였으며, ${\Sigma}{\Delta}$ 변조기는 입력전압 진폭이 100mV가 증가할 때, 출력의 듀티 싸이클은 약 5%씩 증가하였다. 전체회로의 선형성 에러는 0.23% 이하이며, 전류소모는 0.73mA이다. 제안된 회로는 0.35um CMOS 공정을 이용하여 설계되었으며, 입력전압은 3.3V이다. 설계된 칩의 크기는 패드를 포함하여 $1117um{\times}983um$ 이다.

• ETRI Journal
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• 제39권2호
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• pp.292-299
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• 2017

We propose pulse-mode dynamic $R_on$ measurement as a method for analyzing the effect of stress on large-scale high-power AlGaN/GaN HFETs. The measurements were carried out under the soft-switching condition (zero-voltage switching) and aimed to minimize the self-heating problem that exists with the conventional hard-switching measurement. The dynamic $R_on$ of the fabricated AlGaN/GaN MIS-HFETs was measured under different stabilization time conditions. To do so, the drain-gate bias is set to zero after applying the off-state stress. As the stabilization time increased from $ 0.1{\mu}s$ to 100 ms, the dynamic $R_on$ decreased from $160\Omega$ to $2\Omega$. This method will be useful in developing high-performance GaN power FETs suitable for use in high-efficiency converter/inverter topology design.

• 한국정보통신학회논문지
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• 제3권2호
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• pp.339-346
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• 1999

본 논문에서는 INMARSAT-C형 위성통신단발기의 수신단의 회로설계, 제작 및 특성측정을 수행하였다. INA-03184를 이용한 고이득증폭단은 양단 정합된 단일 증폭기 형태로 제작하였으며, 바이어스 안정화 저항을 사용하여 회로의 전압강하 및 전력손실을 가능한 줄이고 온도 안정성을 고려하여 Active 바이어스회로를 사용하였으며, 스퓨리어스를 감쇄시키기 위해서 저잡음증폭기와 고이득증폭단 사이에 대역통과 필터를 사용하였다 측정 결과, 사용 주파수 대역내에서 60 dB 이상의 이득, 44.83 dBc의 스퓨리어스 특성 및 1.8:1 이하의 입ㆍ출력 정재파비를 나타냄으로써 설계시 목표로 했던 사양을 만족시켰다.

• 한국항공우주학회지
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• 제34권5호
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• pp.65-73
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• 2006

위성이 발사체로부터 분리될 때 초기 각속도가 발생한다. B-dot 로직은 일반적으로 위성의 초기각속도 제어에 사용되나, 상대적으로 제어시간이 많이 소요된다는 단점이 있다. 이런 문제를 해결하기 위해 본 논문에서는 피치 바이어스 모멘텀 방식을 사용하는 초소형 위성에 적용 가능한 디텀블링(detumbling) 방식을 새롭게 제안하였다. 제안된 디텀블링 방식은 제어시간이 약 20분 이내로 기존의 방식에 비해 상당한 시간을 줄일 수 있다. 본 논문에서 제안한 디텀블링 방식을 사용할 경우 기존의 모멘텀 휠 초기구동 방식을 사용할 수 없다. 따라서 휠의 속도를 안정적으로 공칭 속도까지 증가시키는 방식을 제안하고 시뮬레이션을 통해 비교, 검증하였다. 시뮬레이션 결과 기존의 방식과 비교했을 때 제어시간을 단축할 수 있었으며 휠의 공칭 속도와 3축 안정화를 이룰 수 있었다.