• 전기전자학회논문지
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• 제5권1호
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• pp.85-90
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• 2001

본 논문에서는 지수함수적인 전력지연 특성을 갖는 나카가미-라이스 페이팅 채널에서 두 개의 반송파로 변조된 광대역 신호의 진폭특성을 분석한다. 그 결과, 분해 가능한 경로 신호들 간의 진폭상관은 신호의 대역폭과 다중경로 신호의 rms지연확산 뿐만 아니라 직접파의 전력과 다중경로 신호의 평균전력의 비에 영향을 받는다.

• 말소리와 음성과학
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• 제1권4호
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• pp.97-103
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• 2009

This paper describes a new algorithm for encoding spectral envelope in the time domain alias cancellation (TDAC) part of G.729.1. The spectral envelope and modified discrete cosine transform (MDCT) coefficients of the weighted code-excited linear predictive (CELP) coding error in lower-band and the higher-band input signal are encoded in the TDAC part. In order to reduce allocation bits for spectral envelope coding, a new algorithm using sub-band correlation between adjacent frames is proposed. In addition, to improve the quality of decoded signals, two bit allocation strategies using reduced bits from the proposed algorithm are proposed. The performance of the proposed algorithm is evaluated in terms of objective quality and bit reduction rates. Experimental results show that the proposed algorithm increases the quality of sounds significantly.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2002년도 추계학술대회논문집
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• pp.611-616
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• 2002

Bearing diagnostics is difficult in a gearbox because bearing signals are masked by the strong gear signals. Self adaptive noise cancellation(SANC) is useful technique to seperate bearing signals from gear signals. While gear signals are correlated with a long correlation length, bearing signals are not correlated with a short length. SANC seperates two components on the basis of correlation length. Then we can find defect frequency component in the envelope spectrum of the bearing signals.

• Architectural research
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• 제7권2호
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• pp.47-54
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• 2005

A photoelectric dimming control system for a small private office space with a double skin envelope system was analyzed for the purpose of examining optimum control performances under a variety of daylight conditions. Computer simulations were performed for the three different photosensor types positioned at the center of ceiling in the space. They were applied in both a south and north-facing room. Daylight conditions were a fixed horizontal venetian blind on an external envelope and a retractable shading device on an internal envelope under a clear, intermediate and overcast sky at different times of a day and year. Partially-shielded photosensors provided good control performances providing the required electric light output under clear and intermediate sky conditions. Unshielded photosensors failed to provide necessary illuminance levels producing less electric output and fully-shielded photosensors generally provided excessive light output. Reasonable electric lighting energy savings were achieved except under overcast sky conditions where the control system did not contribute to energy savings due to the less daylight through envelopes. The retractable shading device covering 50% of the internal envelope reduced energy savings up to 19.62%, but the workplane illuminance levels were maintained within recommended ranges. The coefficients of determination between workplane illuminance and photosensor illuminance due to daylight ranged from 0.74 to 0.98. Partially-shielded conditions provided best correlations and the north-facing room yielded stronger correlation than the south-facing room.

• Smart Structures and Systems
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• 제20권2호
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• pp.197-205
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• 2017

The dynamic performance of railway bridges under high-speed trains draws the attention of bridge engineers. The vibration issue for long-span bridges under high-speed trains is still not well understood due to lack of validations through structural health monitoring (SHM) data. This paper investigates the correlation between bridge acceleration and train speed based on structural dynamics theory and SHM system from three foci. Firstly, the calculated formula of acceleration response under a series of moving load is deduced for the situation that train length is near the length of the bridge span, the correlation between train speed and acceleration amplitude is analyzed. Secondly, the correlation scatterplots of the speed-acceleration is presented and discussed based on the transverse and vertical acceleration response data of Dashengguan Yangtze River Bridge SHM system. Thirdly, the warning indexes of the bridge performance for correlation scatterplots of speed-acceleration are established. The main conclusions are: (1) The resonance between trains and the bridge is unlikely to happen for long-span bridge, but a multimodal correlation curve between train speed and acceleration amplitude exists after the resonance speed; (2) Based on SHM data, multimodal correlation scatterplots of speed-acceleration exist and they have similar trends with the calculated formula; (3) An envelope line of polylines can be used as early warning indicators of the changes of bridge performance due to the changes of slope of envelope line and peak speed of amplitude. This work also gives several suggestions which lay a foundation for the better design, maintenance and long-term monitoring of a long-span high-speed bridge.

• 한국인터넷방송통신학회논문지
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• 제10권6호
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• pp.107-111
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• 2010

차량 주행 중에 타이어에서 발생하는 초음파를 이용하여 손상 물질에 의한 타이어의 손상을 검출하는 방법에 대해 연구하였다. 손상이 있는 타이어는 회전 주기성이 있는 초음파 신호가 발생하므로 주기성을 검출하기 위해 포락선 검출 전처리 과정을 거친 후 자기상관함수를 사용하였다. 실험에서는 손상된 타이어의 1회전 시간과 자기상관함수를 이용해 구한 주기가 같은 것으로 나타났다. 이로 인해 타이어의 손상 유무를 분별할 수 있는 결과를 도출하였다.

• KIEAE Journal
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• 제14권4호
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• pp.61-68
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• 2014

Due to rapid climate changing and the need for energy conservation, environment friendly initiatives have emerged, and regulations to support establishment of green structures in construction have been legislated and enacted. In this study, the supporting of green build method act for rapid climate change and energy conservation. Using green build method, protecting surrounding ecosystem and developing green building continuously, I suggest alternative for protection of the environment. Identifies Envelope Design Elements among various construction Green Building Design Guidelines. Green buildings that we extract the Green Building envelope design from Design Guideline, select the object building through the green buildings examples of public institution relocation projects. Since then analyzes the planned schematic design and Green Envelope Design Elements and Green Building Certification(G-SEED). So, that future directions for planning correlation of Green Building and Design Guidelines about Green Design Elements Can be presented.

• 한국통신학회논문지
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• 제38A권6호
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• pp.512-519
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• 2013

본 논문에서는 합성 이진 옵셋 반송파를 (composite binary offset carrier: CBOC) 위한 새로운 비모호 상관함수를 제안한다. 먼저, CBOC 신호의 부반송파를 네 개의 부분 부반송파의 합으로 해석하고, 각 부분 부반송파들과 수신 신호의 부분 상관들을 생성한다. 이후 생성된 부분 상관을 재조합하여 날카로운 주 첨두를 갖는 새로운 비모호 상관함수를 생성한다. 모의실험의 결과로부터 신호 추적에 제안한 상관함수를 이용한 경우 기존 상관함수들을 이용한 경우보다 더욱 향상된 추적 오류 표준편차와 다중 경로 오류 포락선을 가짐을 확인한다.

• 말소리와 음성과학
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• 제9권1호
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• pp.41-47
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• 2017

The main advantage of the statistical parametric speech synthesis is its flexibility in changing voice characteristics. A personalized text-to-speech(TTS) system can be implemented by combining a speech synthesis system and a voice transformation system, and it is widely used in many application areas. It is known that the fundamental frequency and the spectral envelope of speech signal can be independently modified to convert the voice characteristics. Also it is important to maintain naturalness of the transformed speech. In this paper, a speech synthesis system based on Hidden Markov Model(HMM-based speech synthesis, HTS) using the STRAIGHT vocoder is constructed and voice transformation is conducted by modifying the fundamental frequency and spectral envelope. The fundamental frequency is transformed in a scaling method, and the spectral envelope is transformed through frequency warping method to control the speaker's vocal tract length. In particular, this study proposes a voice transformation method using the correlation between fundamental frequency and vocal tract length. Subjective evaluations were conducted to assess preference and mean opinion scores(MOS) for naturalness of synthetic speech. Experimental results showed that the proposed voice transformation method achieved higher preference than baseline systems while maintaining the naturalness of the speech quality.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2010년도 춘계학술대회 논문집
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• pp.1779-1784
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• 2010

Since PSD(Platform Screen Door) is set up at many subway stations, its design related to a safety becomes gradually important. Especially the intereference check with a running railway vehicle is the most important of performance indices. This study proposes a dynamic analysis models for the railway vehicle and rail. Some design parameters are considered in the models to find a correlation to the performance.