• Bulletin of the Korean Chemical Society
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• v.26 no.1
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• pp.115-118
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• 2005

The miniaturized NIR (Near-infrared) spectrometer has been utilized for the determination of water content (1-19% range) in ethanol that is the most popular organic solvent in pharmaceutical industries. It has many potential capabilities that can replace the conventional analyzers especially for the on-line measurement since it is compact, versatile and cost-effective. By using two dimensional (2D) correlation spectroscopy, it was preliminarily investigated to find any unforeseen spectral distortion among the spectra collected from the miniaturized spectrometer. The 2D study revealed that the spectral variation clearly followed the variation of water concentration without any spectral distortion or abnormality. PLS (Partial Least Squares) was employed to build the calibration model and the resulting prediction performance was acceptable and stable over several days. Even though the miniaturized NIR system was evaluated to fairly simple chemical matrix, the overall study demonstrates the sufficient feasibility for diverse practical and industrial applications.

• Journal of Positioning, Navigation, and Timing
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• v.5 no.1
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• pp.1-9
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• 2016

Range-based wireless localization system must measure accurate range between a mobile node (MN) and reference nodes. However, non-line-of-sight (NLOS) error caused by the spatial structures disturbs the localization system obtaining the accurate range measurements. Localization methods using the range measurements including NLOS error yield large localization error. But filter-based localization methods can provide comparatively accurate location solution. Motivated by the accuracy of the filter-based localization method, a filter residual-based NLOS error estimation method is presented in this paper. Range measurement-based residual contains NLOS error. By considering this factor with NLOS error properties, NLOS error is mitigated. Also a process noise covariance matrix tuning method is presented to reduce the time-delay estimation error caused by the single dynamic model-based filter when the speed or moving direction of a MN changes, that is the used dynamic model is not fit the current dynamic of a MN. The presented methods are evaluated by simulation allowing direct comparison between different localization methods. The simulation results show that the presented filter is more accurate than the iterative least squares- and extended Kalman filter-based localization methods.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• v.1
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• pp.513-517
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• 2006

Autonomous Underwater Vehicles plays specific role in underwater investigation. Generally, this kind of vehicles will move along a planned path for sea bottom or underwater installations inspections, search for mineral deposits along shelves, seeking lost items including bottom mines or for hydrographic measurements. A crucial barrier for it remains the possibility of precise determination of their underwater position. Commonly used radionavigation systems do not work in such circumstances or do not guarantee the required accuracies. In the paper some new solution is proposed on the assumption that it is possible to increase the precision by certain processing of a combination of measurements conducted by means of different techniques. Objective of the paper is the idea of navigation of AUV which consists of two phases: firstly a trip of AUV along pre-planned route and after that postprocessed transformation of collected data in post-processing mode. During the processing of collected data the modern adjustment methods have been applied, mainly estimation by means of least squares and M-estimation. Application of these methods should be associated with the measuring and geometric conditions of navigational tasks and thus suited for specific scientific and technical problems of underwater navigation. The first results of computer aided investigation will be presented and the basic scope of these application and possible development directions will be indicated also. The paper is prepared as an partial results of the works carried out within a framework of the research Project: 'Improvement of the Precise Underwater Vehicle Navigation Methods' financed by the Polish Ministry of Education and Science (No 0 T00A 012 25).

• Bulletin of the Korean Chemical Society
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• v.15 no.12
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• pp.1108-1112
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• 1994

25-Acetoxy-26,27,28-trimethoxycalix[4]arene was synthesized by the treatment of calix[4]arene trimethyl ether with acetyl chloride in the presence of NaH. The solution conformation was inferred as a partial cone conformation based on the $^1H$-and $^{13}C$ NMR spectra. The crystal structure has been determined by X-ray diffraction method. The crystals are monoclinic, space group $P2_1$/n, a=8.186 (1), b=17.137 (2), c=19.878 (3) ${\AA}$, ${\beta}$=95.67 (1)$^{\circ}$, Z=4, V=2774.90 ${\AA}^3$, $D_c$= 1.22 g $cm^{-3}$, $D_m$=1.23 g $cm^{-3}$. The intensity data were collected on an Enraf-Noninus CAD-4 Diffractometer with a graphite monochromated $Cu-K{\alpha}$ radiation. The structure was solved by direct method and refined by full-matrix least-squares methods to a final R value of 0.054 for 3675 observed reflections. The molecule possesses a partial cone conformation with one flattened phenyl unit, in which one anisol ring, distal to the ester ring, is inverted. The acetoxyphenyl ring is flattened.

• Steel and Composite Structures
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• v.39 no.5
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• pp.511-528
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• 2021

There are recently some advances in solving numerically topology optimization problems for large-scaled trusses based on ground structure approach. A disadvantage of this approach is that the final design usually includes many bars, which is difficult to be produced in practice. One of efficient tools is a so-called filter scheme for the ground structure to reduce this difficulty and determine several distinct bars. In detail, this technique is valuable for practical uses because unnecessary bars are filtered out from the ground structure to obtain a well-defined structure during the topology optimization process, while it still guarantees the global equilibrium condition. This process, however, leads to a singular system of equilibrium equations. In this case, the minimization of least squares with Tikhonov regularization is adopted. In this paper, a proposed algorithm in controlling optimal Tikhonov parameter is considered in combination with the filter scheme due to its crucial role in obtaining solution to remove numerical singularity and saving computational time by using sparse matrix, which means that the discrete optimal topology solutions depend on choosing the Tikhonov parameter efficiently. Several numerical examples are investigated to demonstrate the efficiency of the filter parameter control algorithm in terms of the large-scaled optimal topology designs.

• Journal of Distribution Science
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• v.21 no.8
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• pp.47-55
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• 2023

Purpose: Online meeting is chosen instead of face-to-face conferences as a solution that ensures both effectiveness and legality during times of strong epidemic outbreaks. In the current period, managers can have different types of meeting options for information distribution. This study has examined the effect of past behavior on the managers' intention of organizing online meetings. Research design, data and methodology: Data were collected from a survey with 475 managers and put into SmartPLS 4.0 for analysis. Partial least squares structural equation modeling (PLS-SEM) was employed to test relationships in the research model. Results: The findings indicated that past behavior plays the most critical role in explaining the organizing online meeting intention of managers, followed by attitude and subjective norms. Meanwhile, the perceived behavioral control factor has absolutely no effect on intention in the context of this study. Notably, attitude and subjective norms also remarkably mediated the impact of past behavior on managers' intention. Conclusions: This study has added to the understanding of the meeting organization behavior of managers. Even if the epidemic is under control, the administrators should still organize some meetings in the form of online because it will affect the social perceptions of future behavior and behavioral intention.

• Journal of Ocean Engineering and Technology
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• v.28 no.2
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• pp.93-101
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• 2014

In general, particle simulation methods such as the MPS(Moving Particle Simulation) or SPH(Smoothed Particle Hydrodynamics) methods have some serious drawbacks for pressure solutions. The pressure field shows spurious high fluctuations both temporally and spatially. It is well known that pressure fluctuation primarily occurs because of the numerical approximation of the partial differential operators. The MPS and SPH methods employ a pre-defined kernel function in the approximation of the gradient and Laplacian operators. Because this kernel function is constructed artificially, an accurate solution cannot be guaranteed, especially when the distribution of particles is irregular. In this paper, we propose a particle simulation method based on the moving least-square technique for solving the partial differential operators using a Taylor-series expansion. The developed method was applied to the hydro-static pressure and dam-broken problems to validate it.

• Journal of the Korean Data and Information Science Society
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• v.21 no.6
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• pp.1171-1180
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• 2010

It is well known that the asymptotic convergence rates of nonparametric regression estimator gets worse as the dimension of covariates gets larger. One possible way to overcome this problem is reducing the dimension of covariates by using single index models. Two coefficient estimation methods in single index models are introduced. One is semiparametric least square estimation method, which tries to find approximate solution by using iterative computation. The other one is weighted average derivative estimation method, which is non-iterative method. Both of these methods offer the parametric convergence rate to normal distribution. However, practical comparison of these two methods has not been done yet. In this article, we compare these methods by examining the variances of estimators in various models.

• Journal of Korea Water Resources Association
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• v.41 no.3
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• pp.243-249
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• 2008

Continuous stirred tank reactor(CSTR) model which can be applied to control and management of the surface flow wetland is developed to simulate the water quality in this research. The model solution is obtained from the optimization model using the least-squares and 4th-order Runge-Kutta methods. The model is applied to simulate BOD and TSS in the wetland database of U.S. EPA, in which the hydraulic and water quality data are enough and the number of pond is just one for simple analysis of running results. The model is tested in two different cases, one constant volume case and another constant volume and flow rate case considering only reaction term, mass flux term and both reaction and mass flux terms respectively. It is found that the model simulates the real water quality very well with both reaction and mass flux terms rather than only reaction term and the settling velocity of TSS becomes $0.3{\sim}0.4\;m/d$. The model can be applied in wetlands treatment efficiently.

• The Journal of the Acoustical Society of Korea
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• v.18 no.8
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• pp.32-41
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• 1999

In this paper, an inversion method using chirp signals and two near field receivers is proposed. Inversion problems can be formulated into the probabilistic models composed of signals, a forward model and noise. Forward model to simulate chirp signals is chosen to be the source-wavelet-convolution planewave modeling method. The solution of the inversion problem is defined by a posteriori pdf. The wavelet matching technique, using weighted least-squares fitting, estimates the sediment sound-speed and thickness on which determination of the ranges for a priori uniform distribution is based. The genetic algorithm can be applied to a global optimization problem to find a maximum a posteriori solution for determined a priori search space. Here the object function is defined by an L₂norm of the difference between measured and modeled signals. The observed signals can be separated into a set of two signals reflected from the upper and lower boundaries of a sediment. The separation of signals and successive applications of the genetic algorithm optimization process reduce the search space, therefore improving the inversion results. Not only the marginal pdf but also the statistics are calculated by numerical evaluation of integrals using the samples selected during importance sampling process of the genetic algorithm. The examples applied here show that, for synthetic data with noise, it is possible to carry out an inversion for sedimentary layers using the proposed inversion method.