• Phonetics and Speech Sciences
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• v.4 no.1
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• pp.21-28
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• 2012

Many previous studies reported acoustic parameters of English vowels produced by a clear speaking style. In everyday usage, we actually produce speech sounds with various speaking styles. Different styles may yield different acoustic measurements. This study attempts to examine pitch and formant trajectories of eleven English vowels produced by nine American males in order to understand acoustic variations depending on clear and conversational speaking styles. The author used Praat to obtain trajectories systematically at seven equidistant time points over the vowel segment while checking measurement validity. Results showed that pitch trajectories indicated distinct patterns depending on four speaking styles. Generally, higher pitch values were observed in the higher vowels and the pitch was higher in the clear speaking styles than that in the conversational styles. The same trend was observed in the three formant trajectories of front vowels and the first formant trajectories of back vowels. The second and third trajectories of back vowels revealed an opposite or inconsistent trend, which might be attributable to the coarticulation of the following consonant or lip rounding gestures. The author made a tentative conclusion that people tend to produce vowels to enhance pitch and formant differences to transmit their information clearly. Further perceptual studies on synthesized vowels with varying pitch and formant values are desirable to address the conclusion.

• Journal of the Korean Society of Radiology
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• v.9 no.2
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• pp.73-77
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• 2015

In order to observe the detailed structure of the detector, it was CT scanned to reproduce the detailed structure of the crystal shapes and traverse layer using the Monte Carlo calculation applying the detector model. The uncertainty of measurement was lowered by adjusting the detector core by the edge effect at a higher energy (400 keV or higher) through the offset of peak efficiency of the gamma ray at low energy. It was confirmed that there was the appropriate matching with spatial dependency using the PENELOPE calculation. That was achieved by adjusting the parameters describing the crystal core and rounding of edge and crystal core.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.02a
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• pp.319-319
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• 2012

현재 폭넓게 이용되고 있는 STI (Shallow Trench Isolation) 공정에서 active edge 부분에 발생하는 기생 transistor의 subthreshold hump 특성을 제어하는 연구가 활발히 이루어지고 있다. 일반적으로 STI 공정을 이용하는 MOSFET에서 active edge 부분의 얇게 형성된 gate oxide, sharp한 active edge 형성, STI gap-fill 공정 중에 생기는 channel dopant out-diffusion은 subthreshold hump 특성의 주된 요인이다. 이와 같은 문제점을 해결하기 위해 active edge rounding process와 channel dopant compensation의 implantation을 이용하여 subthresold hump 특성 개선을 연구하였다. 본 연구는 STI 공정에 필요한 wafer와 phosphorus를 함유한 wafer를 한 chamber 안에서 auto-doping하는 방법을 이용하여 subthresold hump 특성을 구현하였다. phosphorus를 함유한 wafer에서 빠져나온 phosphorus가 STI 공정중인 wafer로 침투하여, active edge 부분의 channel dopant인 boron 농도를 상대적으로 낮춰 active edge 부분의 가 감소하고 leakage current를 증가시킨다. transistor의 channel length, gate width이고, wafer#No가 클수록 phosphorous를 함유한 wafer까지의 거리는 가까워진다. wafer #01은 hump 특성이 없고, wafer#20은 에서 심한 subthreshold hump 특성을 보였다. channel length 고정, gate width를 ~으로 가변하여 width에 따른 영향을 실험하였다. active 부분에 대한 SCM image로 확인된 phosphorus에 의한 active edge 부분의 boron 농도 감소와 gate width vs curve에서 확인된 phosphorus에 의한 감소가 narrow width로 갈수록 커짐을 확인하였다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.33 no.11C
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• pp.932-939
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• 2008

Recently lattice-reduction (LR) has been used in signal detection for multiple-input multiple-output (MIMO) systems. The conventional LR aided detection schemes are combinations of LR and signal detection methods such as zero-forcing (ZF) and minimum mean square error (MMSE) detection. In this paper, we propose the Lattice-Reduction-aided scheme based on extended noise variance matrix to search good candidate symbol set in quantization step. Then this scheme estimates transmitted symbol with Semidefinite Relaxation by candidate symbol set. Simulation results in a random MIMO system show that the proposed scheme exhibits improved performance and a slight increase in complexity.

• Proceedings of the KIEE Conference
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• 1994.07a
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• pp.208-210
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• 1994

In this paper, the design sensitivity evaluation based on the 2-dimensional finite clement discretization is presented for the voltage source and eddy current problem. And it is applied to the two shape design problems of the rotor slot of 3-phase squirrel cage induction motors. The first is to increase the starting torque while keeping the rated torque fixed. The other is only to increase the torque at the rated speed while keeping the starting torque fixed. As an optimization method, the Gradient Projection method is used to control casily the torques for various speeds of rotor. One fourth of rotor is analyzed by using a semi-periodic boundary condition. Because the shape of rotor slot has much influence on the slip torque characteristic, the 10 design parameters are taken on the interface between rotor core and rotor bar. The initial shape of rotor slot is the trapezoidal typo with rounding corners.

• The Journal of the Korean dental association
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• v.48 no.4
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• pp.297-307
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• 2010

Noncarious cervical lesions(NCCLs) are characterized as structural defects found on the tooth surface of the cement-enamel junction. Loss of tooth structure through noncarious mechanisms may vary in etiology and clinical presentation for each individual but presently many clinician now classify this as tooth failure of abfraction due to the stress applied in the cervical area of the tooth under oral physiological and pathological loads. In the current study, we investigated the stress distribution of maxillary premolar with NCCL using simulated 3D finite element analysis. The results were as follows: 1. In the sound maxillary premolar, the stresses were highly concentrated at cervical enamel surface of the mesiobuccal line angle, asymmetrically. 2. Once the lesion has been formed, the highest stress concentration was observed around the apex of the wedge shaped lesion. 3. In four types of NCCL, the patterns of stress distribution were similar and the peak stress was observed at mesial corner and also stresses concentrated at lesion apex. 4. Lesion cavity modification of rounding apex, reduced stress of lesion apex. 5. When restoring the notch-shaped lesion, material with high elastic modulus worked well at the lesion apex and material with low elastic modulus worked well at the cervical cavosurface margin.

• Journal of Power Electronics
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• v.13 no.1
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• pp.59-69
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• 2013

An alternative technique to control multilevel inverters with vector approximations has been presented. The innovative control method utilizes specially designed two-dimensional hysteresis comparators to simplify the implementation and improve the resultant waveform. The multistage inverter designed with maximum number of levels is operated in such a way to approximate the reference voltage vector by exploiting the large number of multilevel inverter vectors. A three-stage inverter with the main high voltage stage made of three phase, six-switch and singly-fed inverter is considered for application to the proposed design. The proposed control concept is to maintain a higher voltage stage state as long as it can lead to a target vector. High and medium voltage stages controllers are based on surface hysteresis comparators to hold the switching state or to perform the necessary change to achieve its reference voltage with minimal switching losses. The low voltage stage controller is designed to approximate the target reference voltage to the nearest inverter vector using the nearest integer rounding and adjustment comparators. Model simulation and prototype test results show that the proposed control technique clearly outperforms the previous control methods.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.42 no.10 s.340
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• pp.29-34
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• 2005

The maximum quantization error has serious effect on the performance of fixed-width multipliers that receive W-bit inputs and produce W-bit products. In this paper, we analyze the error bound of fixed-width modified Booth multipliers. Then, the estimation method for the number of additional columns for fixed-width multipliers is proposed to limit the maximum quantization error within a desired bound. In addition, it is shown that our methodology can be extended to reduced-width multipliers. By simulations, it is shown that the proposed error analysis method is useful to the practical design of fixed-width modified Booth multipliers.

• The Korean Journal of Zoology
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• v.39 no.2
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• pp.173-181
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• 1996

The time-course process by which spermatozoa penetrates through the micropvle apparatus into the egg cytoplasm of rainbow trout, Oncorhvnchus mvkiss, was examined with transmission and scanning electron microscopy. In the unfertilized egg, the ess surface beneath the inner opening of the micropylar canal did not differ distinctly from the rest of the animal pole area. A spermatozoon attached to the micropvle opening 20 seconds after insemination. In the initial stases of penetration, the spermatozoon still within the micropvlar canal attached perpendicularly at its apical tip to the ess surface, then the sperm head was rapidly engulfed by the folded egg surface with its manly microvilli. A large fertilization cone with microvillus-free surface appeared on the esS surface sutra-rounding the penetrating spermatozoon. The head portion of the penetrating spermatozoon was completely wrapped by the ess surface with only the tail portion visible externally 30 seconds after insemination. The fertilization cone displayed the tail portion of the penetrating spermatozoon on the central portion of its surface 60 seconds after insemination. 150 seconds after insemination, breakdown of the cortical granules elevation were initiated at the animal pole, then completed at the vegetable pole area. The spermatozoon disappeared from the outer surface of the ess before the fertilization cone completely retracted 250 seconds after insemination. In result, the block to polvspermv to permit entry of a sin81e sperm is considered to be mechanical by the rnorpholoSical design of the micropvle and fertilization cone.

• Journal of Life Science
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• v.17 no.10
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• pp.1361-1367
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• 2007

I investigated the effect of KT5720, an inhibitor of protein kinase A, on the vesicular stomatitis virus (VSV) infection in BHK-21cell cultures. The virus inducted cytopathic effect (CPE) was almost completely suppressed by KT5720 at 5uM. The inhibitor, however, did not affect replication of the virus nor the synthesis of viral macromolecules. KT5720, did not block the cytoskeletal disruption, while the cell rounding was suppressed. And, the KT5720-sensitive function may be involved in developing the VSV-induced CPE, but not essential for the virus replications.