• Journal of Korea Multimedia Society
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• v.12 no.3
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• pp.445-450
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• 2009

This paper presents a multi-phase fluid simulation that realistically represents small scale details. We achieve this by creating escaped particles based on physical methods. Escaped particles are the remained particles after correcting levelset. Generation of escaped particles in this paper differs from previous works; this fluid simulation is extended by adding lift force and drag force to positive escaped particles. And negative escaped particles represent droplet or splash effect; when they are merged into the negative levelset value, they affect the nodes' velocity (two-way coupling). This simulation that uses positive and negative escaped particles deals with detailed fluid motions dynamically in small scale.

• Proceedings of the Korean Vacuum Society Conference
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• 2014.02a
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• pp.283.2-283.2
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• 2014

열필라멘트 화학증착공정(Hot Wire Chemical Vapor Deposition)에서 기상 에서 생성되는 하전된 실리콘 나노입자와 저온결정성 실리콘박막 증착의 연관성을 압력의 변화에 따른 상호비교를 통해 조사하였다. 필라멘트 온도는 $1800^{\circ}C$로 고정시키고 0.3~2 torr의 범위에서 공정 압력을 변화시키면서 증착하였다. 압력이 증가함에 따라 증착된 실리콘 박막의 결정화도는 증가하였으며, 증착속도는 감소하였다. 반응기 압력에 따른 기상에서 생성되는 나노입자의 크기분포의 변화를 조사하기 위하여 탄소막이 코팅된 투과전자현미경(Transmission Electron Microscopy) 그리드 위에 실리콘 나노입자를 포획하고 관찰하였다. 포획된 실리콘 나노입자의 크기분포와 개수농도는 압력이 증가함에 따라 감소하였다. 투과전자현미경을 이용하여 분석한 결과, 나노입자는 결정성 구조를 보였다. 압력이 증가함에 따라 나노입자의 크기가 감소하고 개수농도가 감소하는 것은 증착속도의 감소와 관련됨을 알 수 있다. 한편, 공정압력 증가에 따른 나노입자의 크기분포 및 개수농도 감소와 증착속도의 감소는 일반적으로 알려진 기상에서 석출하는 고상의 평형석출량(equilibrium amount of precipitation)이 압력의 증가함에 따라 증가한다는 사실과 일치하지 않는다. 이러한 압력경향성은 Si-H 시스템이 0.3~2 torr의 압력 영역에서 retrograde solubility를 갖는 것을 의미한다. 나노입자의 하전여부, 크기분포 및 개수농도를 측정하기 위하여 입자빔질량분석장비(Particle Beam Mass Spectroscopy)를 이용하였다. 그 결과, 실리콘 나노입자는 양 또는 음의 극성을 가진 하전된 상태임을 확인하였고, 투과전자현미경(TEM) grid에 포획한 실리콘 나노입자의 크기와 경향성이 일치하였다. 이는 나노입자가 저온의 기판에서 핵생성되어 성장하여 생성된 것이 아니라 열필라멘트 주위의 고온영역에서 생성된 것을 의미한다.

• Geophysics and Geophysical Exploration
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• v.5 no.3
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• pp.199-205
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• 2002

In the resistivity method, the potential difference between two grounded electrodes is measured and this can be positive or negative. The apparent resistivity and the potential difference have the same polarity. Since the electric field is the gradient of the potential, the polarity of the potential difference depends on the direction of the electric field. If the direction of the vector connecting two grounded electrodes is the same to that of the electric field, the measured potential difference and the apparent resistivity become positive. If the opposite is the case, they become negative. In general, the primary electric field and the vector connecting two potential electrodes have the same direction in a surface resistivity method. In this case, the measured potential difference is always positive because the primary electric field is greater than the secondary field. Therefore, the apparent resistivity is always positive if noise is free and topography is flat. The secondary field component, however, can be greater than the primary field component along the vector connecting two potential electrodes in the cross-hole resistivity method. Furthermore, if the secondary electric field and the vector connecting two potential electrodes have an opposite direction, the apparent resistivity become negative. Consequently, the apparent resistivity may be negative in the region where the primary electric field component along the vector connecting two potential electrodes is very small.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.32 no.11
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• pp.824-831
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• 2008

We present a continuous size-dependent particle separator using a negative dielectrophoretic (DEP) virtual pillar array. Two major problems in the previous size-dependent particle separators include the particle clogging in the mechanical sieving structures and the fixed range of separable particle sizes. The present particle separator uses the virtual pillar array generated by negative DEP force instead of the mechanical pillar array, thus eliminating the clogging problems. It is also possible to adjust the size of separable particles since the size of virtual pillars is a function of a particle diameter and applied voltage. At an applied voltage of 500 kHz $10\;V_{rms}$ (root mean sqaure voltage) sinusidal wave and a flow rate of $0.40\;{\mu}l\;min^{-1}$, we separate $5.7\;{\mu}m$-, $8.0\;{\mu}m$-, $10.5\;{\mu}m$-, and $11.9\;{\mu}m$-diameter polystyrene (PS) beads with separation purity of 95%, 92%, 50%, and 63%, respectively. The $10.5\;{\mu}m$- and $11.9\;{\mu}m$-diameter PS beads have relatively low separation purity of 50% and 63%. However, at an applied voltage of $8\;V_{rms}$, we separate $11.9\;{\mu}m$-diameter PS beads with separation purity over 99%. Therefore, the present particle separator achieves clog-free size-dependent particle separation, which is capable of size tuning of separable particles.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.27 no.3A
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• pp.196-204
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• 2002

The Sinusoidal Transform Coding(STC) is a vocoding scheme based on a sinusoidal model of a speech signal. The low bit-rate speech coding based on sinusoidal model is a method that models and synthesizes speech with fundamental frequency and its harmonic elements, spectral envelope and phase in the frequency region. In this paper, we propose the 2.4kbps low-rate speech coding algorithm using the sinusoidal model of a speech signal. In the proposed coder, the pitch frequency is estimated by choosing the frequency that makes least mean squared error between synthetic speech with all spectrum peaks and speech synthesized with chosen frequency and its harmonics. The spectral envelope is estimated using SEEVOC(Spectral Envelope Estimation VOCoder) algorithm and the discrete all-pole model. The phase information is obtained using the time of pitch pulse occurrence, i.e., the onset time, as well as the phase of the vocal tract system. Experimental results show that the synthetic speech preserves both the formant and phase information of the original speech very well. The performance of the coder has been evaluated in terms of the MOS test based on informal listening tests, and it achieved over the MOS score of 3.1.

• Journal of Animal Science and Technology
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• v.51 no.5
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• pp.421-426
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• 2009

This study was conducted to clarify the characteristics of vocalization of laying hen related with space in battery cage. The size of cages were classified into control (0.30 m ${\times}$ 0.14 m ${\times}$ 0.55 m, length ${\times}$ width ${\times}$ height), small (0.21 m ${\times}$ 0.14 m ${\times}$ 0.55 m) and large (0.30 m ${\times}$ 0.30 m ${\times}$ 0.55 m) size. Vocalization of 16 individuals of laying hen in each group of Hy-Line Brown (80 week old) were recorded 3 hours per day (10:00am~11:00am, 3:00pm~4:00pm and 7:00pm~8:00pm) using digital recorder and microphone during October 2008 and February 2009. Characteristics of frequency, intensity and duration of vocalization were analyzed by GLM (general linear model) and Duncan's multi-test. There were differences in basic and maximum frequency, and intensity based on analysis of spectrogram and spectrum among different cage sizes. Vocalization of laying hen would be one of the indicators to understand the stress caused by rearing space in batter cage.

• The Journal of the Korea Contents Association
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• v.18 no.11
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• pp.634-642
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• 2018

People with spinocerebellar ataxia, a hereditary and progressive neurogenic disorder, suffer from ataxic dysarthria due to cerebellar dystrophy. This study was designed to examine if intensive motor speech treatment yields improvement in progressive ataxic dysarthria and if then, to investigate magnitude of therapeutic effect. SPEAK $OUT!^{(R)}$ was provided to a 55-year old female diagnosed with SCA for improving motor speech functions. Magnitude of therapeutic effect was large in changes of MPT and vocal intensity across speech tasks. Small effect size was found in changes of fundamental frequency, however, large therapeutic effect was observed in changes of frequency range. In addition, improvement of vocal quality based on jitter, shimmer, and HNR was observed with large therapeutic effect size and vowel space was expanded, particularly, due to F1. Lastly, VHI scores were decreased. Intensive motor speech treatment, called as SPEAK $OUT!^{(R)}$ was effective enough to observe improvement in vocal intensity, frequency range, and vocal quality, expanding vowel space and lowering VHI scores. Based on the results of this case study, further efficacy evaluation of SPEAK $OUT!^{(R)}$ for improving progressive ataxic dysarthria in people with SCA is required.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2009.10a
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• pp.242-243
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• 2009

배기토출음은 공회전시 발생하는 소음에 큰 영향을 끼친다. 연비를 높이기 위하여 공회전시 RPM을 낮추면 엔진 점화 주파수가 낮아지며, 이 경우 배기계 위치에 따른 음향학적 공명 주파수와 일치하면 배기 토출음의 크기가 증가한다. 따라서 본 연구에서는 공회전시 배기토출음을 줄이기 위해 소음기의 위치와 각 배기관들의 길이를 최적화하였다. 최적화 결과로써 3 가지 배기계 위치를 얻을 수 있었고, 실제 실험과의 비교를 통하여 최적화된 배기계 위치가 그렇지 않은 배기계 위치에 비하여 소음 저감량이 높은 것을 확인하였다.

• Proceedings of the Acoustical Society of Korea Conference
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• autumn
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• pp.17-20
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• 1999

본 논문에서는 중첩 가산 Sinusoidal 합성방식에서 위상계승에 의한 단위음 연결법과 다프레임간 정현파 크기의 보간법을 제안한다. 그리고 합성 프레임의 중심이 pitch onset time이라고 가정하고, 음성에서 분리한 성도 모델의 위상을 음성 전체의 위상으로 사용하는 방법을 제안한다. 제안한 방법으로 문서-음성 변환 시스템 (Text-to-Speech System, TTS System)을 구현한 결과 단위음 연결시 연결부분의 파형 왜곡이 감소함을 알 수 있었고, 부드럽게 연결된 합성음을 얻을 수 있었다.

• Proceedings of the IEEK Conference
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• 2001.09a
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• pp.465-468
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• 2001

MPEG-4 Parametric Coding 중 저 비트율로 음성신호를 부호화하는 HVXC(Harmonic Vector excitation Ending)의 복호화 모듈인 LSP 합성필터와 무성음 합성부, 유성음 합성부를 VHDL을 이용하여 구현하였다. MPEG-4 HVXC의 복호화 과정은 코드북을 이용하여 LSP 계수, VXC signal, 그리고 Spectral Envelop이 복호화 되어 각각 LSP 역필터, 무성음과 유성음 합성단을 통과하여 LPC계수와 유,무성음 여기신호로 변환된 후 LPC 합성필터링 과정을 거쳐 최종적으로 음성신호를 출력시킨다. LSP inverse filter에서 사용되는 cosine함수값을 위하여 Table based Approximation을 이용하여 적은 양의 Table 값을 사용하여 정확하고 고속의 cosine 연산을 수행하였다. VXC 복호화 과정에서는 신호의 중복성을 제거하는 Hidden Address in LSH 방법을 사용하여 코드북의 크기를 줄였다. 유성음 합성단에서는 IFFT 모듈을 이용하여 연산속도를 증가 시켰다. 최종적으로 위와 같이 구현된 시스템을 Simulation을 통해 Software 검증을 하였다.