• ETRI Journal
• /
• v.38 no.2
• /
• pp.217-226
• /
• 2016

We propose an architecture that reduces the power consumption and active area of such a modulator through a reduction in the number of active components and a simplification of the topology. The proposed architecture reduces the power consumption and active area by reducing the number of active components and simplifying the modulator topology. A novel second-order loop filter that uses a single operational amplifier resonator reduces the number of active elements and enhances the controllability of the transfer function. A trapezoidal-shape half-delayed return-to-zero feedback DAC eliminates the loop-delay compensation circuitry and improves pulse-delay sensitivity. These simple features of the modulator allow higher frequency operation and more design flexibility. Implemented in a 130 nm CMOS technology, the prototype modulator occupies an active area of $0.098mm^2$ and consumes 5.23 mW power from a 1.2 V supply. It achieves a dynamic range of 62 dB and a peak SNDR of 60.95 dB over a 15 MHz signal bandwidth with a sampling frequency of 780 MHz. The figure-of-merit of the modulator is 191 fJ/conversion-step.

• BMB Reports
• /
• v.37 no.6
• /
• pp.648-656
• /
• 2004

This paper deals with the development of a predictive probabilistic model, a composite dependency-reflecting model (CDRM), which was designed to detect core promoter regions and transcription start sites (TSS) in vertebrate genomic DNA sequences, an issue of some importance for genome annotation. The model actually represents a combination of first-, second-, third- and much higher order or long-range dependencies obtained using the expanded maximal dependency decomposition (EMDD) procedure, which iteratively decomposes data sets into subsets on the basis of dependency degree and patterns inherent in the target promoter region to be modeled. In addition, decomposed subsets are modeled by using a first-order Markov model, allowing the predictive model to reflect dependency between adjacent positions explicitly. In this way, the CDRM allows for potentially complex dependencies between positions in the core promoter region. Such complex dependencies may be closely related to the biological and structural contexts since promoter elements are present in various combinations separated by various distances in the sequence. Thus, CDRM may be appropriate for recognizing core promoter regions and TSSs in vertebrate genomic contig. To demonstrate the effectiveness of our algorithm, we tested it using standardized data and real core promoters, and compared it with some current representative promoter-finding algorithms. The developed algorithm showed better accuracy in terms of specificity and sensitivity than the promoter-finding ones used in performance comparison.

• International Journal of Aeronautical and Space Sciences
• /
• v.14 no.4
• /
• pp.310-323
• /
• 2013

In this paper, the aeroelastic static response of flexible wings with arbitrary cross-section geometry via a coupled CUF-XFLR5 approach is presented. Refined structural one-dimensional (1D) models, with a variable order of expansion for the displacement field, are developed on the basis of the Carrera Unified Formulation (CUF), taking into account cross-sectional deformability. A three-dimensional (3D) Panel Method is employed for the aerodynamic analysis, providing more accuracy with respect to the Vortex Lattice Method (VLM). A straight wing with an airfoil cross-section is modeled as a clamped beam, by means of the finite element method (FEM). Numerical results present the variation of wing aerodynamic parameters, and the equilibrium aeroelastic response is evaluated in terms of displacements and in-plane cross-section deformation. Aeroelastic coupled analyses are based on an iterative procedure, as well as a linear coupling approach for different free stream velocities. A convergent trend of displacements and aerodynamic coefficients is achieved as the structural model accuracy increases. Comparisons with 3D finite element solutions prove that an accurate description of the in-plane cross-section deformation is provided by the proposed 1D CUF model, through a significant reduction in computational cost.

• Journal of Electrical Engineering and Technology
• /
• v.13 no.3
• /
• pp.1265-1274
• /
• 2018

This paper proposes a virtual flux (VF) and positive-sequence power based control strategy to improve the performance of grid-interfaced three-phase voltage source converters against unbalanced and distorted grid conditions. By using a second-order generalized integrator (SOGI) based VF observer, the proposed strategy achieves an AC voltage sensorless and grid frequency adaptive control. Aiming to realize a balanced sinusoidal line current operation, the fundamental positive-sequence component based instantaneous power is utilized as the control variable. Moreover, the fundamental negative-sequence VF feedforward and the harmonic attenuation ability of a sequence component generator are employed to further enhance the unbalance regulation ability and the harmonic tolerance of line currents, respectively. Finally, the proposed scheme is completed by combining the foregoing two elements with a predictive direct power control (PDPC). In order to verify the feasibility and validity of the proposed SOGI-VFPDPC, the scenarios of unbalanced voltage dip, higher harmonic distortion and grid frequency deviation are investigated in simulation and experimental studies. The corresponding results demonstrate that the proposed strategy ensures a balanced sinusoidal line current operation with excellent steady-state and transient behaviors under general grid conditions.

• Journal of the Korean Institute of Rural Architecture
• /
• v.17 no.3
• /
• pp.27-36
• /
• 2015

This research studies the adequate size standard of Seogwipo cruise terminal CIQ facility that is scheduled to be built around Gangjeong harbor area in Seogwipo-city. In order to respond to the highly increasing number of passenger cruise ships compared to Seogwipo cruise terminal design in 2010, the adequate size standard of Seogwipo cruise terminal CIQ facility was examined for passenger service level grade. Based on size computation elements such as the number of passengers of cruise ships with the largest size of port entry, ship landing rate, passenger processing ratio, and surge factor, the CIQ facility size for each service level grade was reviewed. As a result, the area of 2,971m2 (A grade), 2,409 m2 (B grade), and 2,088 m2 (C grade) were computed. This showed that the area of B grade was about 82% and C grade 70% compared to the area of A grade. The CIQ facility size computed for each service level grade in this research was analyzed that its area needed to be increased by 322% at least and 458% at most, compared to the CIQ facility area of 649m2 of the existing design (2010). In order to respond to the increasing number of cruise passengers, provide high-level passenger service, and improve the international image of Jeju, Seogwipo cruise terminal should secure the size that is equal to or higher than the B grade of service level.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2005.11a
• /
• pp.690-695
• /
• 2005

Flexible circular cantilever beams when excited externally introduce a lot of dynamic characteristics. The non-linear elements that these flexible beams develop include non-linearity due to inertia terms, spring, and damping. They show different characteristics of motion from each other. In the modes of lower order, the non-linearity due to spring is prevalent, while the non-linearity due to inertia Is prevalent in the modes of higher order. To analyze these effects the non-linear phenomena are analyzed experimentally. When the response characteristics of non-linear vibration are analyzed using autospectrum, it is possible to analyze the subharmonic and superharmonic mot ion by comparison. The phase change is analyzed using the method of phase portrait and the non-linear characteristics of response characteristics that are developed in flexible structures can be predicted and applied to the stage of design.

• Journal of the Korea Society of Computer and Information
• /
• v.7 no.1
• /
• pp.112-119
• /
• 2002

We propose an enhanced wavelet packet image coder algorithm which is based on the coefficients partition. The proposed wavelet packet image coder uses the first-order entropy to reduce the total compression time, and achieves low bit rates and rate-distortion performance by the zero-tree based coding using correlations between coefficients partition. This new algorithm represents new parent-children relationships for reducing image reconstruction error using the correlations between each frequency subbands and then the wavelet packet coefficients are Partitioned by a new order. The computer simulations demonstrate higher PSNR under the same bit rate and improved image compression time and enhanced rate control compare with conventional algorithms. From the simulation results, it is shown that the encoding and decoding process of proposed coder are much simple and accurate than present method against texture images , which include many mid-frequency elements.

• Journal of Science Education
• /
• v.35 no.2
• /
• pp.250-261
• /
• 2011

The purpose of this study is to analyze how the content elements of the environment education are displayed between related subjects in elementary school curriculum and find a desirable direction of the environment education. Major subjects that handle the components of the environment education include science, physical education, social studies, ethics, and practical arts. Among these subjects, science aims for the ecological perspective, social studies aims for rational decision making and practical behaviors, and ethics aims for the correct formation of environmental ethics and values. In the component ratio of the environment education, the domains of the natural environment, environmental ethics, environmental pollution, environmental protection and measure were higher. In the formation of content elements according to grades, the connectivity of the environment curriculum has been relatively well secured in the order of the learning about the environmental components, awareness on environmental problems and the measures and efforts to overcome environmental problems. Based on the findings above, the followings are proposed for future environment curriculum in elementary school. First, it is necessary to increase the ratio of the ecological perspective based on science and coordinate the period to suggest this contents. Second, it is necessary to complement the contents of social studies regarding green growth and sustainable development which have become global issues in the environment education. Third, Pan-curriculum and integrated discussions to prepare multi-academic and interdisciplinary environment curriculum have to be preceded and through this process it is necessary to set the target of environment education and select the content elements of the curriculum.

• Journal of Nutrition and Health
• /
• v.12 no.3
• /
• pp.25-32
• /
• 1979

In order to investigate harmful trace elements in ford additives used in food processing the contents of Copper, Lead, Cadmium, Chromium, Manganese, Nickel and Iron are determined by Atomic Absorption Spectrophotometer. These Elements are Extracted with APDC-MIBK extract method. Samples are collected from the food Industrial companies in Korea. Samples studied as shown in Table 1 are food colors(3-samples, Flavoring Agents(7-samples), Acidifiers(4-samples) Baking Powders(4-samples), Emulsifiers(2-samples), Thickeners(2-samples), Antioxidants(2-samples), Intensifiers(2-samples), Seasonings(3-samples), modifiers (10-samples) Most of the food additives contained comparatively a little small amount of harmful trace elements. However, the contents of harmful trace elements of Sodium Carbonate, Food Yellow No.5, Food Blue No.1, Food Red No.2 and Alkalies added in noodles are significantly higher than the other food additives. The obtained results are as follows ; 1) Sodium Carbonate contained Cadmium; 16.73 ug/g and Lead ; 61.55 ug/g. 2) Food Yellow No. 5 contained Cadmium: 1.67ug/g and Lead; 23.46 ug/g. 3) Food Blue No. 1 contained Cadmium; 1. 16 ug/g and Lead; 23.46 ug/g. 4) Food Red Ho. 1 contained Cadmium; 1.91 ug/g and Lead 23.08 ug./g. 5) Alkalies added in noodles contained Cadmium; 6. 11 ug/g and Lead; 53.85 ug/g.

• Journal of Korean Society of Environmental Engineers
• /
• v.32 no.1
• /
• pp.69-78
• /
• 2010

In order to investigate the degree of household dust contamination, 48 samples of household dust (24 from urban area and 24 from rural area) in Daegu city were collected in vacuum cleaner during January to February 2009. Samples were sieved below 100 ${\mu}m$, and 14 elements (Al, Ca, Cd, Cr, Cu, Fe, K, Mg, Mn, Na, Ni, Pb, V, Zn) were analyzed using ICP after acid extraction. Results obtained from the source assessment of trace elements using enrichment factor showed that Ca, Fe, K, Mg, Mn, Na, and V were influenced by natural sources such as weathered rock and resuspended soil, while Cd, Cr, Cu, Ni, Pb and Zn were influenced by anthropogenic sources such as fuel combustion and waste incineration. Concentrations were remarkably higher in components from natural sources than in components from urban anthropogenic sources. Household dust in urban area was more affected by anthropogenic sources compared with that of rural area. Pollution index of heavy metals revealed that urban area was 1.8 times more contaminated with heavy metal components than rural area. The correlation analysis among trace elements indicated that components were correlated with natural sources-natural sources (Al-Mg, Al-Mn, Fe-Mn) and natural sources-anthropogenic sources (Al-V, Fe-Cr, V-Mn) in both urban area and rural area. Trace element components of rural area were more correlated than those of urban area. Houses that use oil for heating fuel had relatively higher contents of heavy metals rather than those using gas or electricity for heating fuel. Houses with children also had higher contents of heavy metals. In addition, the age of houses was found to influence the heavy metal levels in household dusts, with older houses (>10years) having higher concentrations than newer houses (<10years) and houses located near the major road (<10 m) were found to have relatively higher heavy metal levels in household dust.