• Journal of Microbiology and Biotechnology
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• 제11권6호
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• pp.915-921
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• 2001

Phytase improves the bioavailability of phytate phosphorus in plant foods to humans and animals, and reduces the phosphorus pollution of animal waste. In order to express a high level of fungal phytase in Saccharomyces cerevisiae, various expression vectors were constructed with different combinations of promoters, translation enhancers, signal peptides, and terminator. Three different promoters fused to the phytase gene (phyA) from Aspergillus niger were tested: a galactokinase (GAL1) promoter, glyceraldehyde-3-phosphate dehydrogenase (GPD) promoter, and yeast hybrid ADH2-GPD promoter consisting of alcohol dehydrogenase II (ADH2) and a GPD promoter. The signal peptides of phytase, glucose oxidase (GO), and rice amylase 1A(RAmy1A) were included. Plus, the translation enhancers of the ${\Omega}$ sequence and UTR70 from the tobacco mosaic virus (TMV) and spinach, respectively, were also tested. Among the recombinant vectors, pGphyA06 containing the GPD promoter, the ${\Omega}$ sequence, RAmy1A, and GAL7 terminator expressed the highest phytase activity in a culture filtrate, which was estimated at 20 IU/ml. An intracellular localization of the expressed phytase activity in a culture filtrate, which was estimated at 20 IU/ml. An intracellular localization of the expressed phytase was also performed by inserting an endoplasmic reticulum (ER) retention signal, KDEL sequence, into the C-terminus of the phytase within the vector pHphyA-6. It appeared that the KDEL sequence directed most of the early expression of phytase into the intracellular compartment yet more than $60\%$ of the total phytase activity was still retained within the cell even after the prolonged (>3 days) incubation of the transformant. However, the intracellular enzyme activity of the transformant without a KDEL sequence was as high as that of the extracellular one, thereby strongly suggesting that the secretion of phytase in S. cerevisiae appeared to be the rate-limiting step for the expression of a large amount of extracellular recombinant phytase, when compared with other yeasts.

• 한국통신학회논문지
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• 제30권12A호
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• pp.1153-1160
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• 2005

일반적인 OFDM/QAM 시스템은 시간 영역에서 다중경로 채널에 강인한 특성을 갖기 위해 연속적인 심볼 사이에 보호구간(Guard Interval)을 삽입하는 반면, OFDM/OQAM(Offset QAM)-IOTA 시스템은 보호구간 대신에 시간과 주파수 영역에서 우수한 Localization 특성을 갖는 IOTA(Isotropic Orthogonal Transform Algorithm) 함수를 사용하며, 이로 인하여 OFDM/OQAM-IOTA 시스템은 현저하게 높은 주파수 사용 효율을 갖는다. 하지만 일반적인 OFDM/QAM 시스템에 사용된 채널 추정 방법을 변경 없이 OFDM/OQAM-IOTA 시스템에 적용할 경우 고유의 심볼간 간섭(ISI : Inter-Symbol Interference)이 발생하게 되므로 OFDM/OQAM-IOTA 시스템 채널 추정을 위해서는 별도의 프리앰블 구조를 사용하여야 한다. 본 논문에서는 OFDM/OQAM-IOTA 시스템 채널 추정에 적합한 새로운 프리앰블 구조를 제안하고, 제안된 프리앰블을 사용하여 Ideal 채널 추정과 중저속 이동 환경에서의 Practical 채별 추정을 수행하여, 그 결과를 일반적인 OFDM/QAM 시스템의 성능과 비교 분석한다. 시뮬레이션 결과에 의하면, 제안된 프리앰블 구조를 사용한 OFDM/OQAM-IOTA 시스템이 FFT 크기의 1/4을 보호구간으로 사용하는 일반적인 OFDM/QAM 시스템보다 Target BER 10-3에서 1.5 dB 정도의 Eb/NO 이득이 있으며, 또한 $25\%$ 정도의 데이터 전송률 이득을 갖는다.

• 방송공학회논문지
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• 제2권1호
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• pp.65-73
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• 1997

본 논문에서는 대용량 지형 정보 데이터를 효과적으로 3차원 도시하기 위하여 wavelet 변환을 이용한 효과적이고 새로운 삼각형 메쉬 근사 기법과 압축 저장 기법을 제안한다. 제안된 방법은 wavelet 변환 계수의 공간-주파수 지역제한 특성을 이용하여 지형정보 데이터를 영역분할하고 각 영역에 대해 삼각형 메쉬를 생성하므로써 계산량이 적고 알고리즘이 간단하다는 장점이 있다. 또한 Embedded Zerotree Wavelet 부호화 기법을 도입하여 지형 정보데이터의 효과적인 저장, 관리는 물론 삼각형 메쉬 구성기법에 적용하였다. 제안된 지형정보 데이터의 3차원 고속도시기에는 데이터 압축, 저장 및 Level of Detail 구현에 이르는 모든 기법을 통합되었으며 모의실험을 통하여 높은 PSNR, 고속 수행, 간단한 구현 등의 장점들을 갖는 것이 확인되었다.

• 한국기계가공학회지
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• 제18권8호
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• pp.98-103
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• 2019

A more accurate method of feature point extraction and matching for three-dimensional reconstruction using low-resolution images of crops is proposed herein. This method is important in basic computer vision. In addition to three-dimensional reconstruction from exact matching, map-making and camera location information such as simultaneous localization and mapping can be calculated. The results of this study suggest applicable methods for low-resolution images that produce accurate results. This is expected to contribute to a system that measures crop growth condition.

• Investigative Magnetic Resonance Imaging
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• 제25권3호
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• pp.156-163
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• 2021

Recently, neuromelanin and nigrosome imaging techniques have been developed to evaluate the substantia nigra in Parkinson's disease. Previous studies have shown potential benefits of quantitative analysis of neuromelanin and nigrosome images in the substantia nigra, although visual assessments have been performed to evaluate structures in most studies. In this study, we investigate the potential of using deep learning based automatic region segmentation techniques for quantitative analysis of the substantia nigra. The deep convolutional neural network was trained to automatically segment substantia nigra regions on 3D nigrosome and neuromelanin sensitive MR images obtained from 30 subjects. With a 5-fold cross-validation, the mean calculated dice similarity coefficient between manual and deep learning was 0.70 ± 0.11. Although calculated dice similarity coefficients were relatively low due to empirically drawn margins, selected slices were overlapped for more than two slices of all subjects. Our results demonstrate that deep convolutional neural network-based method could provide reliable localization of substantia nigra regions on neuromelanin and nigrosome sensitive MR images.

• Progress in Superconductivity
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• 제3권1호
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• pp.56-59
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• 2001

We have constructed a multi-channel SQUID magnetometer system for localization and classification of magnetic targets. Ten SQUID magnetometers were arranged to measure 5 independent components of 3 $\times$ 3 magnetic field gradient tensor. To get gradient from the difference of magnetic field measurements, we carefully balanced magnetometers. SQUIDs with slotted washer were used for operation in an unshielded laboratory environment, and noise characteristic in the laboratory was measured. With the multi-channel SQUID magnetometer system, we have successfully traced the motion of a bar magnet moving around it at a distance of about 1 m. In the urban environment, the drift of uniform magnetic field due to the irregular motion of a large magnetic body at distance and earth field causes an error in the position calculation, and this results in the distortion of the calculated trajectory. In this paper, we present the architecture and the performance of the system.

• Transactions on Control, Automation and Systems Engineering
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• 제3권4호
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• pp.223-228
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• 2001

We have been developed an intelligent mobile robot with an artificial olfactory function to recognize odours and to track odour source location. This mobile robot also has ben installed an engine for speech recognition and synthesis and is controlled by wireless communication. An artificial olfactory system based on array of 7 gas sensors has been installed in the mobile robot for odour recognition, and 11 gas sensors also are located in the obttom of robot to track odour sources. 3 optical sensors are also in cluded in the intelligent mobile robot, which is driven by 2 D. C. motors, for clash avoidance in a way of direction toward an odour source. Throughout the experimental trails, it is confirmed that the intelligent mobile robot is capable of not only the odour recognition using artificial neural network algorithm, but also the tracking odour source using the step-by-step approach method. The preliminary results are promising that intelligent mobile robot, which has been developed, is applicable to service robot system for environmental monitoring, localization of odour source, odour tracking of hazardous areas etc.

• 열처리공학회지
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• 제9권3호
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• pp.212-218
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• 1996

To clarify the influence of precipitation microstructure and inclusion on the monotonic tensile fracture behaviors in 2090 alloy aged at $180^{\circ}C$, the detailed measurement of hardness, tensile strength, elongation and the observation of scanning electron micrography, transmision electron micrography have been carried out. The transgranular shear ductile fracture has been observed in specimen quenched after solution treatment at $500^{\circ}C$ for 45min. While the under-aged specimen was fractured in both transgranular shear ductile and intergranular fracture mode, the fracture mode of peak-aged and over-aged alloy was predominantly intergranular fracture. The fracture behavior of each ageing condition was influenced by the change of precipitation microstructural features. In the case of peak-aged and over-aged alloys, the coarse and heterogeneous slip band caused by both shearable nature of the ${\delta}^{\prime}(Al_3Li)$ precipitates and PFZ along the high angle grain boundary aid the localization of deformation, resulting in low energy intergranular fracture. It was also estimated that the fractured T-type intermetallic phases (inclusion) and the equilibrium ${\delta}$(AlLi) phases which were formed at grain boundaries palyed an important role in promoting intergranular fracture mode.

• 한국소음진동공학회논문집
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• 제16권4호
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• pp.428-436
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• 2006

The assessment of an urban site depends on the way whether it responds to multiple needs such as functionality, aesthetic and complex comfort of acoustic, thermal, lighting and air quality etc. This study aims to investigate the assessment of various urban soundscapes in the sense of acoustic amenity by the questionnaires. As a result, acoustic amenity assessment was influenced by the non-acoustic factors such as environment assessment of visual, thermal, air quality etc. In the sense of sound quality, urban environmental sound was interpreted as 3 factors of strength, evolution of time, spacial localization. So these factors would be considered in the new assessment method for acoustic amenity. And it was shown that the subjects tend to perceive the noise level less than $3{\sim}5dB\;L_{eqA}$ according to the urban landscapes under the similar noise exposure level.

• Journal of Power Electronics
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• 제16권3호
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• pp.1163-1175
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• 2016

In recent years, microgrids have been the focus of considerable attention in distributed energy distribution. Microgrids contain a large number of power electronic devices that can potentially cause negative impedance instability. Harmonic impedance is an important tool to analyze stability and power quality of microgrids. Harmonic impedance can also be used in harmonic source localization. Precise measurement of microgrid impedance and analysis of system stability with impedances are essential to increase stability. In this study, we introduce a new square wave current injection method for impedance measurement and stability analysis. First, three stability criteria based on impedance parameters are presented. Then, we present a new impedance measurement method for microgrids based on square wave current injection. By injecting an unbalanced line-to-line current between two lines of the AC system, the method determines all impedance information in the traditional synchronous reference frame d-q model. Finally, the microgrid impedances of each part and the overall microgrid are calculated to verify the measurement results. In the experiments, a simulation model of a three-phase AC microgrid is developed using PSCAD, and the AC system harmonic impedance measuring device is developed.