• Structural Engineering and Mechanics
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• 제56권4호
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• pp.625-648
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• 2015

Modern super-tall buildings are more sensitive to strong winds. The evaluation of wind loads for the design of these buildings is of primary importance. A direct monitoring of wind forces acting on super-tall structures is quite difficult to be realized. Indirect measurements interpreted by inverse techniques are therefore favourable since dynamic response measurements are easier to be carried out. To this end, a Kalman filtering based inverse approach is developed in this study so as to estimate the wind loads on super-tall buildings based on limited structural responses. The optimum solution of Kalman filter gain by solving the Riccati equation is used to update the identification accuracy of external loads. The feasibility of the developed estimation method is investigated through the wind tunnel test of a typical super-tall building by using a Synchronous Multi-Pressure Scanning System. The effects of crucial factors such as the type of wind-induced response, the covariance matrix of noise, errors of structural modal parameters and levels of noise involved in the measurements on the wind load estimations are examined through detailed parametric study. The effects of the number of vibration modes on the identification quality are studied and discussed in detail. The made observations indicate that the proposed inverse approach is an effective tool for predicting the wind loads on super-tall buildings.

• 한국분말재료학회지
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• 제3권4호
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• pp.271-278
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• 1996

In this study, the effect of the transition elements on the microstructure and mechanical properties of rapidly solidified Al-Mg-X alloys was investigated. As a result of the rapid solidification processing, fine equiaxed grains with a mean diameter of 2 $\mu$m were observed in these alloys. Many fine particles were found to be distributed rather homogeneously throughout the matrix with relatively large particles occasionally at grain boundaries. The ultimate tensile strengths of Al-Mg-X alloys were found to decrease rather remarkably at 150 $^{\circ}C$ without the gain of the ductility at 150 $^{\circ}C$, which may result from segregation of $\beta$ ($Al_{3}Mg_{2}$) precipitates. Fine dimples were observed on the fracture surfaces for all alloy systems and the variation of the size and shape of dimples was not observed upon alloy systems. The ductility at 530 $^{\circ}C$ was found to be ~100%, suggesting that grain boundary sliding did not contribute to ductiliy despite he grain size stabilization. The absence of superplastic behavior may be associated with low boundary misorientation in rapidly solidified Al-Mg-X alloys.

• 한국인쇄학회지
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• 제26권1호
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• pp.51-64
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• 2008

In this paper, an experiment was done where the input(scanner, digital still camera) and monitor(CRT, LCD) device used the linear multiple regression and the GOG (Gain-Offset-Gamma) characterization model to perform a color transformation. Also to color conversion method of the digital printer it used the LUT(Look Up Table), 3dimension linear interpolation and a tetrahedron interpolation method. The results are as follows. From color reappearance of digital printing case of monitor, the XYZ which it converts in linear multiple regression of input device it multiplied the inverse matrix, and then it applies the inverse GOG model and after color converting the patch of the result most which showed color difference below 5 at monitor RGB value. Also, The XYZ which is transmitted from the case input device which is a printer it makes at LAB value to convert an extreme, when the LAB value which is converted calculating the CMY with the LUT and tetrahedral interpolations the color conversion which considers the black quantity was more accurate.

• Journal of Communications and Networks
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• 제5권2호
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• pp.141-149
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• 2003

In this paper, we investigate design criteria and the performance of the space-frequency bit-interleaved coded modulation (SF-BICM) systems in frequency-selective Rayleigh fading channels. To determine the key parameters that affect the performance of SF-BICM, we derive the pairwise error probability (PEP) in terms of the determinant of the matrix corresponding to any two codewords. We prove that the bit-interleavers do the function of distributing the nonzero bits uniformly such that two or more nonzero bits are seldom distributed into the symbols that are transmitted in the same frequency bin. This implies that the bit-interleavers transform an SF-BICM system into an equivalent 1-antenna system. Based on this, we present design criteria of SFBICM systems that maximizes the diversity order and the coding gain. Then, we analyze the performance of SF-BICM for the case of 2-transmit antennas and 2-multipaths by deriving a frame error rate (FER) bound. The derived bound is accurate and requires only the distance spectrum of the constituent codes of SF-BICM. Numerical results reveal that the bound is tight enough to estimate the performance of SF-BICM very accurately.

• Journal of Positioning, Navigation, and Timing
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• 제9권3호
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• pp.207-214
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• 2020

In this paper, we implement linear-quadratic-Gaussian based vector tracking loop (LQG-VTL) instead of conventional extended Kalman filter based vector tracking loop (EKF-VTL). The LQG-VTL can improve the performance compared to the EKF-VTL by generating optimal control input at a specific performance index. Performance analysis is conducted through two factors, frequency thermal noise and frequency dynamic stress error, which determine total frequency tracking error. We derive the thermal noise and the dynamic stress error formula in the LQG-VTL. From frequency tracking error analysis, we can determine control gain matrix in the LQG controller and show that the frequency tracking error of the LQG-VTL is lower than that of the EKF-VTL in all C/N0 ranges. The simulation results show that the LQG-VTL improves performance by 30% in Doppler tracking, so the LQG-VTL can extend pre-integration time longer and track weaker signals than the EKF-VTL. Therefore, the LQG-VTL algorithm is more robust than the EKF-VTL in weak signal environments.

• 치과방사선
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• 제27권1호
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• pp.17-24
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• 1997

The purpose of the present study was to use digital profile image features and digital image analysis of fixed-dimension bone regions, extracted from standardized periapical radiographs of the maxilla, to determine whether differences exist in alveolar bone of younger women(mean age: 59.23±7.34 years) and just menopaused women(mean age: 59.23±7.34). Periapical films were used from two groups of 20 randomly selected women. None of the subjects had a remarkable medical history. To simplify protocol, we chose one interproximal bone area between the maxillary right canine and lateral incisor for study. Ech film was digitized into a 1312 x 1024 pixel x 8 bit depth matrix by means of a Nikon 35 mm film scanner(LS-35lOAF, Japan) with fixed gain and internal dark current correction to maintain constant illumination. The scanner was interfaced to a Macintosh LC III computer(Apple Computer, Charlotte, N.C.). Area and profile orientation were selected with a NIMH Image 1.37(NIH Research Services Branch, Bethesda, Md.). Histogram features were extracted from each profile and area. The results of this study indicate that mean pixel intensities didn't differ significantly between two groups and there was a high correlarion-coefficient between digitized radiographic profile features and area features.

• 한국전기전자재료학회논문지
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• 제14권2호
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• pp.111-116
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• 2001

Poly-Si TFT's(Polysilicon thin filmtransistors) have been actively studied due to their applications in active matrix liquid crystal displays and active pull-up devices of CMOS SRAM's. For such applications, the leakage current has to be in the range of sub-picoampere. However, poly-Si TFT's suffer from anomalous high leakage currents, which is attributed to the emission of the traps present at gain boundaries in the drain junction. The leakage current has been analyzed by the field emission via grain-boundary traps and thermionic field emission over potential barrier located at the grain boundary. We found that the models proposed before are not consistent with the experimental results at far as drain-offset poly-Si TFT's we fabricated concern. In this paper, leakage current of drain-offset poly-Si TFT's with different offset lengths was studied. A conduction model based on the thermionic emission of the tunneling electrons is developed to identify the leakage mechanism. It was found that the effective grain size of the drain-offset region is important factor in the leakage current. A good agreement between experimental and simulated results of the leakage current is obtained.

• 한국생물정보학회:학술대회논문집
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• 한국생물정보시스템생물학회 2004년도 The 3rd Annual Conference for The Korean Society for Bioinformatics Association of Asian Societies for Bioinformatics 2004 Symposium
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• pp.244-249
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• 2004

There have been many attempts to predict the secondary structure content of a protein from its primary sequence, which serves as the first step in a series of bioinformatics processes to gain knowledge of the structure and function of a protein. Most of them assumed that prediction relying on the information of the amino acid composition of a protein can be successful. Several approaches expanded the amount of information by including the pair amino acid composition of two adjacent residues. Recent methods achieved a remarkable improvement in prediction accuracy by using this expanded composition information. The overall average errors of two successful methods were 6.1% and 3.4%. This work was motivated by the observation that evolutionarily related proteins share the similar structure. After manipulating the values of the frequency matrix obtained by running PSI-BLAST, inputs of an artificial neural network were constructed by taking the ratio of the amino acid composition of the evolutionarily related proteins with a query protein to the background probability. Although we did not utilize the expanded composition information of amino acid pairs, we obtained the comparable accuracy, with the overall average error being 3.6%.

• 한국인터넷방송통신학회논문지
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• 제16권1호
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• pp.15-20
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• 2016

공간다중화 방식을 사용하는 MIMO 시스템은 다이버시티 기법을 사용하는 MIMO 시스템과 비교할 때 높은 전송률을 달성하지만 다이버시티 이득이 낮아 데이터 전송 신뢰도를 높이기 위하여 MIMO 수신단에서 공간정보스트림을 분리해야한다. 본 논문에서는 격자부호에 의한 채널 용량 검출 기법, 사용자 3인인 간섭채널과 선형검출기법인 ZF(Zero Forcing)와 MMSE(Minimum Mean Square Error) 검파 기법을 비교했다. 이때 채널은 Diagonal 채널이 된다. 즉, Diagonal 채널은 $[H]_N[H]_N^{-1}=[I]_N$로 역행렬이 element-wise inverse로 Jacket 행렬의 성질을 만족함을 확인했다.

• 한국IT서비스학회지
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• 제11권sup호
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• pp.61-74
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• 2012

As the retail industry has been challenged by stiff competition, the retailer becomes more interested in better understanding consumers' in-store behavior to gain and sustain competitive advantage. Consumers' shopping paths provide valuable clues to understanding customers' in-store behavior, which has been a long standing research issue in business. This study is to explore the shopping path patterns in a grocery using RFID technology and clustering method. To this end, we designed the RFID systems, affixing active RFID tags to the bottom of grocery carts. The tag emit signal that is received by receptors installed at various location throughout the store. The RFID systems provide the time and location of the cart while consumers shop around the store. The point of sale data are matched with the cart movement records to provide a complete picture of each shopping path. To find the distinctive patterns of consumers' shopping paths, we proposed the distance-index matrix using dijkstra method and normalization method to conduct the clustering in order to handle the problem in measuring the similarity among shopping paths, which is raised by the spatial nature of consumer movement in a grocery. After analyzing the RFID data obtained in one of the groceries in a major Korean retailer, we could successfully identify several distinctive patterns of shopping paths, which prove to provide the valuable implications for store management.