• The Journal of the Acoustical Society of Korea
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• v.13 no.4
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• pp.20-31
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• 1994

The maximum likelihood(ML) estimation has excellent accuracy for frequency estimation of multiple sinusoids, but the maximum likelihood function requires much loss owing to the high nonlinearity. This paper presents a simplified maximum likelihood estimation, in order to improve the nonlinearity of the maximum likelihood estimation for frequencies of sinusoids in signals. This method is applied to the frequency estimation of sinusoidal signals corrupted by white or colored measurement noise. Monte-carlo simulations are conducted for the comparison of ML method with the best MFBLP method, in terms of sampled mean, root mean square and relative bias. The power spectral density and the position of frequency in unit circle are appeared in figures.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2004.04a
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• pp.35-38
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• 2004

부틸알데히드로 오염된 대상 부지에 Biosparging 공법의 현장 적용을 위해 적정 공기 주입 압력 조건을 도출한 결과, 주 오염층인 자갈질 모래층에 공기주입 가능 파괴압력(Pe)는 약 300mmAq로 측정되었으며 4,500mmAq 압력 조건에서는 용존 산소농도의 영향 반경이 약 3 m로 나타났다. 위의 조건을 적용하여 약 150일간 운전한 결과, 영양물질을 투입하지 않은 초기 90일 동안 최고농도 대비 약 90%가 저감되었으며 그 이후에 영양물질을 투입하여 초기 최고 농도 대비 96%가 저감되어 복원목표치인 50ppm을 모든 지역에서 만족시켰다. 또한 생분해 반응속도가 k=0.03/day로 나타나 휘발성이 낮고 생분 해도가 뛰어난 부틸알데히드로 오염된 자갈질 모래층에 Biosparging공법이 성공적으로 적용된 사례이다.

• The Safety technology
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• no.182
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• pp.24-26
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• 2013

SK하이닉스는 PC, 모바일 등 각종 IT기기의 필수부품인 D램과 낸드플래시 등 메모리반도체를 비롯해 CIS와 같은 시스템반도체 등을 생산하는 기업이다. 1984년 국내 최초로 16Kb S램을 시험 생산한 이래, 세계 최초 최소 최고속 최저전압의 혁신적인 제품을 연이어 시장에 선보이며 이제는 반도체업계의 선두기업 반열에 당당히 올라섰다. 세계 메모리반도체 2위, 세계 최대 반도체 시장인 중국 등 신흥시장에서 D램 부문 1위 등이 그 증거다. 우리 식탁의 기본인 쌀처럼 반도체는 IT산업의 핵심으로 꼽힌다. 더불어 반도체는 단순한 부품을 넘어 이제 IT제품의 성능을 구분 짓는 잣대로까지 평가받고 있다. 때문에 고품질의 반도체를 생산하기 위한 이곳 임직원들의 열정과 노력은 상당하다. 환경안전 관리는 바로 이런 노력을 뒷받침하는 주축이다. 이런 신념에 따라 이곳은 쾌적한 근무환경 조성에 매진하는 한편 안전을 최우선으로 하여 모든 작업을 진행하고 있다. 반도체분야 최정상 기업의 지리를 유지하기 위해 환경안전관리에 매진하고 있는 SK하이닉스 이천 본사를 찾아가봤다.

• Journal of Life Science
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• v.21 no.10
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• pp.1452-1459
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• 2011

Citrus is a common term and genus (Citrus) of flowering plants in the rue family, Rutaceae. Citrus is believed to have originated in the part of Southeast Asia bordered by Northeastern India, Myanmar (Burma) and the Yunnan province of China. The taxonomy and systematics of the genus are complex and the precise number of natural species is unclear, as many of the named species are clonally propagated hybrids, and there is genetic evidence that even some wild, true-breeding species are of a hybrid origin. One of the most popular sequences for phylogenetic inference at the generic and infrageneric levels in plants is the chloroplast trnL-trnF region. We evaluated the seven taxa with the trnL-trnF region to estimate phenotypic relationships within the genera Citrus, Poncirus, and Fortunella in Korea. Alignment of the DNA sequences required the addition of numerous gaps. Sequence variation within Citrus was mostly due to insertion/deletion. Within the genus Citrus, C. lomonia and C. sinensis were relatives and sistered with C. aurantium in the four phylogenetic analyses (MP, ML, ME, and NJ). However, some external nodes were poorly supported.

• The Transactions of the Korean Institute of Power Electronics
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• v.11 no.1
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• pp.29-37
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• 2006

Precise control of interior permanent magnet synchronous motor(IPMSM) over wide speed range is an engineering challenge. This paper considers the design and implementation of novel technique of high performance speed control for IPMSM using learning mechanism-fuzzy neural network(LM-FNN) and ANN(artificial neural network) control. The hybrid combination of neural network and fuzzy control will produce a powerful representation flexibility md numerical processing capability. Also, this paper proposes speed control of IPMSM using LM-FNN and estimation of speed using artificial neural network controller. The back propagation neural network technique is used to provide a real time adaptive estimation of the motor speed. 'The error between the desired state variable and the actual one is back-propagated to adjust the rotor speed, so that the actual state variable will coincide with the desired one. The back propagation mechanism is easy to derive and the estimated speed tracks precisely the actual motor speed. Analysis results to verify the effectiveness of the new hybrid intelligent control proposed in this paper.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.12 no.3
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• pp.1289-1301
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• 2011

In this paper, flux estimation method at the Induction motor is applied to stability flux estimate of possibility in overall speed domain. angle operation has voltage and current and speed information using the Induction motor direct control method. Induction motor direct control is material to flux information. Exact flux estimation method to using current model flux estimator of low-speed domain and voltage model flux estimator of high-speed domain. Speed and current and flux controller using PI controller. And error of integral requital for add to Anti-Windup PI controller. Verified to performance of Current model Flux controller and voltage model flux controller using Matlab / Simulink. Analysis has parameter influence of direct vector control and indirect vector control at the Induction motor vector control. So, verified to minute control. Analyzed to simulation result and proof to validity of presented algorithm.

• Journal of the Korean Society for Railway
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• v.15 no.1
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• pp.37-41
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• 2012

Kyung-Bu High Speed Railway is operated in train control system(tcs) of fixed block operated in a way of dividing track circuits into several blocks in accordance with operation circumstances such as rolling stocks, grade, curves and facilities. The TCS of fixed block system refers to a continuous train control system, which transfers operational information such as entry and exit speed, distance-to-go, and deceleration etc. into on-board train control equipment on the basis of block occupancy of a preceding train. It guarantees a safe operation of trains by giving an emergency braking order, in case that a train exceeds an entry and exit speed of a corresponding block. In this paper, we analyze the speed control code deducing in accordance with maximum operation speed and characteristics of rolling stocks by analyzing principles of generation of speed control code allocated in blocks for safe operation, then train operational efficiency was analyzed by means of analysis of operation headway in accordance with the deduced speed control code. This study will be used to design in case of getting an increase in speed for existing high speed line or new high speed line TCS.

• Journal of the Korean Institute of Landscape Architecture
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• v.41 no.6
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• pp.140-146
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• 2013

This experiment was conducted in order to study the physiological characteristics of Sedum takevimense in different moisture conditions. The photosynthetic rate, water use efficiency and the respiratory rate were determined by using a photable photosynthesis system. According to the results, the best illumination range and moisture range were explicitly selected. The highest photosynthetic rate was at $600{\mu}mol{\cdot}m^{-2}{\cdot}s^{-1}$, and after this value, the trend showed a reduction. When the moisture was 11.31%, the photosynthetic capacity and water use efficiency reached maximum value, but the respiratory rate reached maximum value at 7.91%. According to the measured values, the best illumination range was $600{\sim}1,200{\mu}mol{\cdot}m^{-2}{\cdot}s^{-1}$ and the best moisture range was 7.09~11.31%.

• Journal of Korea Multimedia Society
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• v.10 no.9
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• pp.1197-1208
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• 2007

These days, most of SMART card, JAVA card, picked up the JAVA Card Platform gets the position as a standard. Java Card technology provides implantation, platform portability and high security function to SMART Card. Compared to normal Smart Card, JAVA card has a defect that is a low running speed caused by a distinctive feature of JAVA programming language. Factors that affect JAVA Card execution speed are the method how to save the data and install the applets of JAVA Card installation instrument. In this paper, I will offer the plan to improve JAVA Card program's loading and execution speed. At Java Card program, writing, updating and deleting process for data at EEPROM can be improved of Java Card speed by using high speed RAM. For this, at JAVA Card as a application of RAM, I will present prefetching LRU-ORL Buffer Cache Technique that is suitable for Java Card environment. As a data character, managing all data created from JAVA Curd at Buffer Cache, decrease times of recording at maximum for EEPROM so that JAVA Card program upload and execution speed will be improved.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.23 no.12
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• pp.1666-1672
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• 2019

A closed loop wireless transmission method adaptive to mobile unit speed is proposed in this paper. A mobile communication node measures the mobile speed based on the transmitted pilot signals through Doppler frequency estimation, and it changes the transmission period of pilot signals as per estimated mobile speed adaptively. The pilot signals with the different transmission periods are transmitted using the different PN sequences with the previous ones without any explicit information about the new period. The corresponding receiver node can detect and extract the transmitted pilot signals through blind search of the transmitted PN sequences of the pilot signals, and it can demodulate and decode the transmitted information using the channel estimation results based on the detected pilot signals. The performance of the proposed method had been analyzed through the simulation under the fading channel environments and compared with the previous methods. The simulation results showed performance improvement of the proposed method over the existing ones.