• Journal of Astronomy and Space Sciences
• /
• v.26 no.1
• /
• pp.59-74
• /
• 2009

Relative navigation system is presented using GPS measurements from a single-channel global positioning system (GPS) simulator. The objective of this study is to provide the real-time inter-satellite relative positions as well as absolute positions for two formation flying satellites in low earth orbit. To improve the navigation performance, the absolute states are estimated using ion-free GRAPHIC (group and phase ionospheric correction) pseudo-ranges and the relative states are determined using double differential carrier-phase data and singled-differential C/A code data based on the extended Kalman filter and the unscented Kalman filter. Furthermore, pseudo-relative dynamic model and modified relative measurement model are developed. This modified EKF method prevents non-linearity of the measurement model from degrading precision by applying linearization about absolute navigation solutions not about the priori estimates. The LAMBDA method also has been used to improve the relative navigation performance by fixing ambiguities to integers for precise relative navigation. The software-based simulation has been performed and the steady state accuracies of 1 m and 6 mm ($1{\sigma}$ of 3-dimensional difference errors) are achieved for the absolute and relative navigation using EKF for a short baseline leader/follower formation. In addition, the navigation performances are compared for the EKF and the UKF for 10 hours simulation, and relative position errors are mm-level for the two filters showing the similar trends.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.30 no.1C
• /
• pp.18-24
• /
• 2005

In this paper, a new trellis-coded differential unitary space-time modulation (TC-DUSTM) scheme based on amplitude/phase-shift-keying (APSK) signals is proposed. In particular, the design criterion of the trellis coding is proposed to combine the trellis coding and DUSTM scheme based on APSK constellation. From the computer simulations, we verify the superiority of the proposed TC-DUSTM based on APSK signals at the higher transmission rate. In addition, the proposed scheme can suppress the irreducible error of the differential scheme.

• Proceedings of the KSME Conference
• /
• 2004.04a
• /
• pp.2017-2022
• /
• 2004

There are multistage preheaters in the power generation plan to improve the thermal efficiency of the plant and to prevent the components from the thermal shock. The energy source of these heaters comes from the extracted two phase fluid of working system. These two-phase fluid can cause the so-called Flow Accelerated Corrosion(FAC) in the extracting piping and the bubble plate of the heater for example, in case of point Beach Nuclear Power Plant and in the Wolsung Nuclear Power Plant. The FAC is due to the mass transport of the thin oxide layer by the convection. FAC is dependent on many parameters such as the operation temperature, void fraction, the fluid velocity and pH of fluid and so on. Therefore, in this paper velocity was calculated by FLUENT code in order to find out the root cause of the wall thinning of the feedwater heaters. It also includeed in the fluid mixing analysis model are around the number 5A feedwater heater shell including the extraction pipeline. To identify the relation between the local velocities and wall thinning, the local velocities according to the analysis results were compared with distribution of the shell wall thicknes by ultrasonic test.

• Journal of IKEEE
• /
• v.21 no.1
• /
• pp.70-72
• /
• 2017

We proposed a multi-input multi-output automatic repeat request (MIMO-ARQ) scheme using double multi-strata space-time code (D-MSSTC) for high spectral efficiency in $4{\times}N_r$ MIMO systems. To improve error performance of the proposed scheme, we allocate power and phase to each layer of MSSTC over every transmission. Additionally, we suboptimally optimize power allocation to maximize the minimum coding gain distance of D-MSSTC and phase allocation to efficiently minimize inter-layer interference in MSSTC. In simulation results, it is observed that the proposed MIMO-ARQ scheme based on D-MSSTC shows better block error rate (BLER) performance than conventional schemes.

• Land and Housing Review
• /
• v.1 no.1
• /
• pp.59-65
• /
• 2010

The paper presents a comparison between a semi-implicit time integration linear finite element implementation and fully-implicit nonlinear Newton-Raphson finite element implementation of a triphasic small strain mixture formulation of an elastic partially saturated porous medium. The pore air phase pressure pa is assumed atmospheric, i.e., $p_a$ = 0, although the formulation and implementation are general to handle increase in pore air pressure as a result of loading, if needed. The solid skeleton phase is assumed linear isotropic elastic and partially saturated 'consolidation' in the presence of surface infiltration and traction is simulated. The verification of the implementation against an analytical solution for partially saturated pore water flow (no deformation) and comparison between the two implementations is presented and the important of the porosity-dependent nature of the partially saturated permeability is assessed on comparison with a commercial code for the partially saturated flow with deformation. As a result, the response of partially saturated permeability subjected to the porosity influences on the saturation of a soil, and the different behaviors of the partially saturated soil between staggered and monolithic coupled programs is worth of attention because the negative pore water pressure in the partially saturated soil depends on the difference.

• Molecules and Cells
• /
• v.27 no.2
• /
• pp.237-241
• /
• 2009

Pathogens Burkholderia pseudomallei (Bp) and Burkholderia mallei (Bm) contain a large number (> 12,000) of Simple Sequence Repeats (SSRs). To study the extent to which these features have contributed to the diversification of genes, we have conducted comparative studies with nineteen genomes of these bacteria. We found 210 genes with characteristic types of SSR variations. SSRs with nonamer repeat units were the most abundant, followed by hexamers and trimers. Amino acids with smaller and nonpolar R-groups are preferred to be encoded by the variant SSRs, perhaps due to their minimal impacts to protein functionality. A majority of these genes appears to code for surface or secreted proteins that may directly interact with the host factors during pathogenesis or other environmental factors. There also are others that encode diverse functions in the cytoplasm, and this protein variability may reflect an extensive involvement of phase variation in survival and adaptation of these pathogens.

• The Transactions of the Korean Institute of Electrical Engineers
• /
• v.45 no.2
• /
• pp.301-309
• /
• 1996

This paper estimates the electric field effect near 765[kV] AC double transmission line with numerical data. The induced voltage and current of a human and car under who kinds of phase arrangement are calculated when each of two objects is insulated or grounded. When the calculated results of the low-reactance and superposition phase arrangement are compared, it is proved that the induced voltage and current of the former are about 30 [%] smaller than that of the latter. The induced current of a human and car are less than 0.5[mA] which is about 10[%] less than that of the American National Standard Code. Also the induced voltage and current of dead lines by other live lines are calculated. Finally the effective number and position of shield wires to reduce the field in ground level are considered. charge simulation method and surface charge method are used to simulate the 2 or 3 dimensional transmission line model respectively.

• The KIPS Transactions:PartD
• /
• v.8D no.6
• /
• pp.843-852
• /
• 2001

Statistics concerning software errors indicate that more errors are introduced in analysis and design phase than implementation phase. Therefore, it is needed to check whether the design modeling is appropriate for own function and structure. This paper discussed the effective test method for the object-oriented design model, i.e., UML. A new method was proposed for generating test data. This method consists of category partition theory by the representation each element in UML model with OCL (Object Constraint Language). Test data generated in this way can be used for testing the source code functionality as well as for checking the design model.

• International Journal of Automotive Technology
• /
• v.7 no.3
• /
• pp.345-351
• /
• 2006

Software-In-the-Loop Simulation(SILS) and Rapid Control Prototyping(RCP) are proposed as an integrated development environment to support the development process from system design to implementation. SILS is an environment used to simulate control systems with temporal behavior. RCP offers seamless phase shift from design to implementation based on automatic code generation. There are several toolsets that support control system design and analysis. A few of these tools generate the control software automatically. However, most of these design toolsets do not cover temporal behavior which appears after implementation. In earlier toolsets, the design and the implementation of a control system are considered as two separate processes which mean the conventional development process is not connected strictly. SILS/RCP environments work under an identical platform and use the same representation for system modeling. An integrated SILS/RCP environment makes it possible to design controllers under conditions similar to real execution during off-line simulation and to realize controllers in the early design phase. SILS/RCP environments integrate the design and implementation phases which reduce the time-to-market and provide greater performance-assured design. The establishment of SILS/RCP and the practical design approaches are presented.

• Journal of the Institute of Convergence Signal Processing
• /
• v.1 no.2
• /
• pp.105-114
• /
• 2000

In this paper, we propose a bandwidth-efficient channel coding scheme using the turbo trellis-coded modulation with multiple symbol detection. The turbo code can achieve good bit error rates (BER) at low SNR. That comprises two binary component codes and an interleaver. TCM codes combine modulation and coding by optimizing the euclidean distance between codewords. This can be decoded with the Viterbi or the symbol-by- symbol MAP algorithm. But we present the MAP algorithm with branch metrics of the Euclidean distance of the first phase difference as well as the Lth phase difference. The study shows that the turbo trellis-coded modulation with multiple symbol detection can improve the BER performance at the same SNR.