• 말소리와 음성과학
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• 제2권3호
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• pp.141-148
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• 2010

In this paper, voice activity detection (VAD) for dual-channel noisy speech recognition is proposed in which spatial cues are employed. In the proposed method, a probability model for speech presence/absence is constructed using spatial cues obtained from dual-channel input signal, and a speech activity interval is detected through this probability model. In particular, spatial cues are composed of interaural time differences and interaural level differences of dual-channel speech signals, and the probability model for speech presence/absence is based on a Gaussian kernel density. In order to evaluate the performance of the proposed VAD method, speech recognition is performed for speech segments that only include speech intervals detected by the proposed VAD method. The performance of the proposed method is compared with those of several methods such as an SNR-based method, a direction of arrival (DOA) based method, and a phase vector based method. It is shown from the speech recognition experiments that the proposed method outperforms conventional methods by providing relative word error rates reductions of 11.68%, 41.92%, and 10.15% compared with SNR-based, DOA-based, and phase vector based method, respectively.

• 한국실내디자인학회논문집
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• 제27권3호
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• pp.3-13
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• 2018

Although the number of dual low-income families continues to increase, working mothers are suffering from difficulties from housework and child rearing due to the economic difficulties and poor residential environment. By understanding the needs about community space and child-care support services, this study will look into planning cooperative child-care environments for dual low-income families with infants and children. Through purposive sampling this research targeted 151 dual income families with an average monthly income level of 1-3 in Seoul. The collected data was analyzed by frequency analysis, descriptive statistics, and independent sample t-test using SPSS. The research results are as follows: According to the review, respondents responded positively to cooperative child-care. Out of the 20 general community spaces, the need for an indoor playground, recreation room, day nursery, separate garbage and reading room ranked high. Overall, 21 child-care community spaces and 11 child-care support services were generally rated highly.

• 한국정보통신학회:학술대회논문집
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• 한국해양정보통신학회 1999년도 춘계종합학술대회
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• pp.78-81
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• 1999

L1 band (1575.42MHz)를 이용한 GPS 수신기의 위치 및 시간 오차는 대략 100 m 와 70 ns 정도로 알려져 있으며, 이 오차의 주원인 중 하나가 위성신호가 대기권을 통과할 때 전리층에서 생기는 전파지연이다. 이러한 전리충의 전파 지연을 정확하게 검출하여 수신기의 위치 오차와 시간 오차를 보정해 주기 위해 사용되는 방식으로서 L1/L2 dual-band를 이용하는 GPS 수신기가 있다. Dual-band GPS 수신기는 한 위성에서 보내는 Ll 밴드 (1575.42MHz) 신호와 L2 밴드 (1227.6MHz) 신호가 각각 전리층을 통과할 때 주파수에 따라 전파 지연 값이 다르다는 것을 이용하여 지연 값을 보정해 주는 원리를 이용한 것이다. 본 논문에서는 Synopsys사의 COSSAP 틀을 이용하여 L1/L2 듀얼 밴드 GPS 수신기의 구조를 상위레벨 시뮬레이션을 통하여 분석하였다.

• 한국ITS학회 논문지
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• 제12권4호
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• pp.66-75
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• 2013

나노미터 크기의 Spintronics 발진기 어레이를 기반으로 Spintronics 발진기의 주파수 및 진폭을 동시에 변조하는 새로운 스핀변조를 실현할 수 있다. 본 논문에서는 실현된 스핀 변조신호를 무선으로 수신하기 위해 듀얼 채널를 처리하는 수신기를 설계하였다. 최종적으로 얻어진 Spintronics 발진기 어레이에서 만들어진 스핀변조 신호를 수신기의 두 채널을 통해서 동시에 처리 할 수 있었으며, 각 채널당 최종적으로 200 kbps급 까지의 데이타 전송을 실현하였다. Spintronics 발진기의 신호 레벨 -60 dBm 크기의 한계로 1 cm 이하의 근접거리 통신에서 가능하며, 듀얼 채널 수신기는 $56{\times}33mm^2$ 크기이다.

• 대한물리의학회지
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• 제6권1호
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• pp.19-29
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• 2011

Purpose : The purpose of study was to investigate effects of dual task balance training on balance and activities of daily living(ADL) in Stroke patient. Methods : The purpose of study was to investigate effects of dual task balance training on balance and activities of daily living(ADL) in Stroke patient. Results : The results of this study were summarized as follows: There were significant improvement in balance and ADL following the training in experimental group. There were significant improvement in a part of balance following the training in control group, whereas there were no significant improvement in ADL following the training in control group. There were significant difference following training in both groups in balance and ADL. The level of statistical significance was <05. Conclusion : Based on the results of this study, dual task balance training have an effects on balance and ADL in stroke patients.

• The Journal of Korean Physical Therapy
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• 제30권5호
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• pp.199-203
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• 2018

The number of reported cases with dual disability is increasing for the past few decades. Currently, dual disability of lower limb amputation and motor weakness after stroke became a strong issue in public concern. The functional levels of patients have shown in the wide range from independent community ambulation to non-ambulation. Thus, it indicates that favorable outcomes for dual disability may depend upon adopted rehabilitative strategies. We present the case of a man with left below-knee amputation and severe right-sided weakness following a huge putaminal hemorrhage. He had suffered from extreme pain and misfit of the prosthetic socket and the complicated residual limb for three years prior to the stroke. Forty days post-stroke, we performed a revision surgery to resolve the complications of bony overgrowth, verrucous hyperplasia, and neuroma and applied an ankle foot orthosis (AFO). Two years post-stroke, he was able to ambulate outside his home and negotiate stairs using a cane. This is the first case with the dual disability of lower limb amputation and contralateral hemiplegia to undergo revision surgery. The results suggest that an early revision surgery and use of an AFO are crucial for achieving a higher level of mobility in such cases.

• Journal of electromagnetic engineering and science
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• 제10권4호
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• pp.309-315
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• 2010

A dual-band dual-polarized microstrip antenna array for an advanced multi-function radio function concept (AMRFC) radar application operating at S and X-bands is proposed. Two stacked planar arrays with three different thin substrates (RT/Duroid 5880 substrates with $\varepsilon_r$=2.2 and three different thicknesses of 0.253 mm, 0.508 mm and 0.762 mm) are integrated to provide simultaneous operation at S band (3~3.3 GHz) and X band (9~11 GHz). To allow similar scan ranges for both bands, the S-band elements are selected as perforated patches to enable the placement of the X-band elements within them. Square patches are used as the radiating elements for the X-band. Good agreement exists between the simulated and the measured results. The measured impedance bandwidth (VSWR$\leq$2) of the prototype array reaches 9.5 % and 25 % for the S- and X-bands, respectively. The measured isolation between the two orthogonal polarizations for both bands is better than 15 dB. The measured cross-polarization level is ${\leq}-21$ dB for the S-band and ${\leq}-20$ dB for the X-band.

• Journal of electromagnetic engineering and science
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• 제13권2호
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• pp.93-103
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• 2013

This paper presented a novel approach for the design of a tunable dual-band bandpass filter (BPF) with independently tunable passband center frequencies and bandwidths. The newly proposed dual-band filter principally comprised two dual-mode single band filters using common input/output lines. Each single BPF was realized using a varactor-loaded transmission line resonator. To suppress the harmonics over a broad bandwidth, a defected ground structure was used at the input/output feeding lines. From the experimental results, it was found that the proposed filter exhibited the first passband center frequency tunable range from 1.48 to 1.8 GHz with a 3-dB fractional bandwidth (FBW) variation from 5.76% to 8.55%, while the second passband center's frequency tunable range was 2.40 to 2.88 GHz with a 3-dB FBW variation from 8.28% to 12.42%. The measured results of the proposed filters showed a rejection level of 19 dB up to more than 10 times the highest center frequency of the first passband.

• 전력전자학회논문지
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• 제27권2호
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• pp.126-133
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• 2022

This study proposes a suppression of zero sequence current (ZSC), which is caused by zero sequence voltage (ZSV) for a dual two-level inverter with single DC bus. Large output voltages enable the dual inverter with single DC bus to improve a system efficiency compared with single inverter. However, the structure of dual inverter with single DC bus inevitably generates ZSC, which reduces the system efficiency and causes a current ripple. ZSV is also produced by dead time, and its magnitude is determined by the DC bus and current direction. This study presents a novel space vector modulation method that allows the instantaneous suppression of ZSC. Based on a condition where a switching period is twice a sampling (control) period, the proposed control method is implemented by injecting the offset voltage at the primary inverter. This offset voltage is injected in half of the switching period to suppress the ZSC. Simulation and experiments are used to compare the proposed and conventional methods to determine the ZSC suppression performance.

• 실천공학교육논문지
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• 제16권2호
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• pp.215-226
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• 2024

본 연구는 일학습병행 사업관계자 직무연수 참여자 2,543명의 교육훈련 만족도 조사 결과를 활용하여 일학습병행 공동훈련센터 전담자를 주 대상으로 한 교육훈련의 성과분석을 진행하고, 교육과정 효과성 제고를 위한 시사점을 제시하였다. 연구 결과 일학습병행 공동훈련센터 전담자 교육훈련은 매우 높은 수준의 학습자 만족도를 나타내 성공적인 교육훈련을 제공한 것으로 평가되었다. 교육과정 운영 현황 및 교육 참여자 특성은 학습자 만족도에 영향을 미치는 것으로 나타났으며, 강사·주제·시설환경·운영 측면의 만족은 모두 교육과정 만족에 유의한 영향력을 미치는 것으로 나타났다.