• Journal of the Korean Chemical Society
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• v.38 no.4
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• pp.283-287
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• 1994

The crystal stucture of bithional surfoxide, $C_{12}H_6Cl_4O_3S$, has been determined from 2295 independent reflections collected on an automated CAD-4 diffractometer with a graphite-monochromated $Mo-K\alpha$ radiation. The crystal belongs to the monoclinic, space group P2$_1$/n, with a unit cell dimensions a = 12.448(4), b = 9.740(1), c = $11.815(2)\AA$, $\beta$ = $100.06^{\circ}$, $\mu$ = 9.02 cm$^{-1}$, Dm = 1.76 g/cm$^3$, Dc = 1.75 g/cm$^3$, F(000) = 744, and Z = 4. The structure was solved by the direct method and refined by the least-squares method. The final R values was 0.037 for 2295 independent reflections. Overall conformation of the molecule is folded with respect to central surfur atom. Comparing with the molecular conformation of bithional, one of phenyl rings was swinged with about $180^{\circ}.$ This conformational change in the molecule results in the existance of intramolecular-hydrogen bond of S-O(3)---H-O(1) type and its steric hindrance between this moiety and the other phenyl ring. The two best planes of the phenyl rings have a maximum deviation of 0.009 $\AA$ for C(1) atom. The dihedral angle between two phenyl rings is $99.22^{\circ}.$ In the crystal structure, the molecules are packed with intermolecular-hydrogen bond of O(3)---H-O(2).

• Geophysics and Geophysical Exploration
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• v.4 no.4
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• pp.124-132
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• 2001

Electrical resistivity survey has been conducted for delineating geological fault structure in Kaekok-ri near Kyungju. In general, electrical resistivity survey has an advantage of searching buried faults and its traces compared with other geophysical survey methods. Distribution of electrical conductivity in the ground is influenced by the ratio of pores, groundwater and clay minerals. These properties are evidenced indirectly to explain for weathering condition, faults and fracture Bones. Thus the electrical resistivity survey can be an effective method to find buried faults. We have carried out two dimensional (2-D) interpretation by means of smoothness-constrained least-squares and finite element method. Field data used in this paper was acquired at Kaekok-ri, Wuedong-eup, Kyungju-si, where is Ulsan Fault and is close to the region in which debatable quaternary fault traces were found recently. The dipole-dipole array resistivity survey which could show the 2-D subsurface electrical resistivity structure, was carried out in the area with three lines. The results showed good property of fault, fracture zone and fault traces which we estimated were congruous with the results. Through this study, 2-D electrical resistivity survey interpretation for fault is useful to apply.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.38 no.12
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• pp.1387-1394
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• 2014

In a photoelastic experiment, it is necessary to know the material stress fringe constant of the photoelastic specimen to determine the stresses from the measured isochromatic fringe orders. The material stress fringe constant can be obtained using a simple tension specimen and/or a circular disk under diametric compression. In these methods, there is generally a need to apply numerous loads to the specimen in response to the relationship of the fringe order. Then, the least squares method is used to obtain the material constant. In this paper, the fringe orders that appear on a four-point bending specimen are used to determine the fringe constant. This method requires four photoelastic fringes obtained from a circular polariscope by rotating the analyzer to 0, ${\pi}/4$, ${\pi}/2$, and $3{\pi}/4$ radians. Using the four-point bending specimen to determine the material stress fringe constant has an advantage because measurements can be made at different locations by applying a constant load. The stress fringe constant measured with this method is within the range suggested by the manufacturer of the photoelastic material.

• Journal of Korean Society of Forest Science
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• v.97 no.1
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• pp.45-52
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• 2008

The objectives of this study are to explain a supply plan of domestic softwood log by long-term prospect of MDF production to stably promote industry of MDF. For it, we developed the long supply function as Ordinary Least Squares Method. Between 2005 and 2050, it was estimated that quantity of domestic production of MDF increased from 1,653 thousand $m^3$ to 2,041 thousand $m^3$. In 2050, quantities of domestic softwood log used by raw materials to product MDF of 2,041 thousand $m^3$ were estimated to be used about 1,355 thousand $m^3$. Exampling Pinus rigida used presently by raw materials to product MDF, cutting area of it is estimated to be 10,828 ha per year. And larch is cutted about 9,160 ha per year. This study estimated annual softwood log cutting amount and total afforestation area at 2050 year by 3 scenarios which are 35%, 45% and 55% about use of domestic softwood log for MDF production. If we do a criterion of cutting area, we advantage to plant larch. But the species of trees are use and growth property. We think that the afforestation policy must be performed on the base of those to supply raw materials of MDF. Although government plans hardwood afforestation policy after cutting Pinus rigida, it needs to support and manage certainly afforestation area of softwoods to need to supply raw materials of MDF to stably promote industry of MDF.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.46 no.3
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• pp.210-218
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• 2018

In order to generate meshes automatically for finite element analysis of complex structures such as aircraft, a large number of triangular elements are typically created. However, triangular elements are less accurate than rectangular elements, so it is difficult to obtain a reliable solution. This problem can be improved through the meshfree method using the back cell integration. However, this method also causes some problems such as over-use of the integration points and inefficiency of the integral domain. In order to improve these problems, a method of performing integration by setting the integral area based on a node basis has been proposed, but in the case of incompressible material problems, the numerical accuracy deteriorates due to the vibration phenomenon of the solution. Therefore, in this paper, the modified meshfree method is proposed which sets the integral domain as an element domain instead of the nodal domain, and the proposed method improves the numerical instability caused by the conventional meshfree method without decreasing the accuracy regardles of the shape of integral domain. The effectiveness of the modified meshfree method is verified by using 2-D examples.

• Journal of Advanced Marine Engineering and Technology
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• v.40 no.7
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• pp.647-654
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• 2016

Indoor localization based on visible-light communication using the received signal strength intensity (RSSI) has been widely studied because of its high accuracy compared with other wireless localization methods. However, because the RSSI can vary according to the inclination and azimuth of the receiver, a large error can occur, even at the same position. In this paper, we propose a visible-light communication-based 3-D indoor positioning algorithm using the Gauss-Newton technique in order to reduce the errors caused by the change in the inclination of the receiver. The proposed system reduces the amount of computations by selecting the initial position of the receiver through the linear least-squares method (LSM), which is applied to the RSSIs, and improves the position accuracy by applying the Gauss-Newton technique to the 3-D nonlinear model that contains the RSSIs acquired by the changes in the azimuth and inclination of the receiver. In order to verify the validity of the proposed algorithm in an indoor space with dimensions of $6{\times}6{\times}3m$ where 16 LED lights are installed, we compare and analyze the errors of the conventional linear LSM-based trilateration technique and the proposed algorithm according to the changes in the inclination and azimuth of the receiver. The experimental results show that the location accuracy of the proposed algorithm is improved by 82.5% compared to the conventional LSM-based trilateration technique.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.24 no.3
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• pp.149-158
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• 2012

This study analyzed cross-sectional variations in residual current and strengths of stratification by observing cross-sectional velocity and salinity during spring tide and neap tide, respectively, for continuous 13-hour periods at 2 observation lines at northern and southern end of Seokmo Channel, which is located west of Ganghwado. Salinity distribution of channel depends on not only neap and spring tide but also impact of salinity. The residual current component was obtained by removing $M_2$ and $M_4$ tidal components that were extracted using the least squares method on 13-hour velocity component. Cross-section of residual velocity at northern and southern end of Seokmo Channel exhibited southward residual components at channel's surface layer, but northward residual current was observed at channel's bottom layer, clearly showing a 2-layer tidal circulation between surface and bottom layers. The variation in location of appearing northward residual current according to changes in spring and neap tidal cycle and its correlation with stratification were analyzed using the Richardson number and Simpsonhunter index. At northern and southern end of Seokmo Channel, northward residual current appears in the location where Richardson number is large, Simpson-hunter index appears as a value greater than 4.

• Journal of Digital Convergence
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• v.15 no.5
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• pp.99-106
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• 2017

The purpose of this study is to analyze the relationship between tourist 's intention to use smartphone and the preceding factors through the questionnaire. For achieving this research purpose, this study surveyed the tourists who use smartphone to investigate the influence of interactivity such as two-way communication and synchronicity as hypotheses on the influence of flow, and the effect of attitude factors on continuous intention to use was analyzed by research model. In this study, a partial least squares based structural equation (PLS-SEM) method was applied to verify the hypothesis of the proposed research model. Finally, the validity of the proposed research model was confirmed through confirmatory factor analysis and hypothesis testing. Therefore, the results of this study show that interactivity and flow are influential for the reuse of users in utilizing information by using smartphone, and it affects the attitude of users in developing smart tourism system in the future. The results of this study can be utilized as basic data related to the acquisition of information by smartphone of tourists in the future development of smart tourism system.

• Journal of Astronomy and Space Sciences
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• v.20 no.1
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• pp.29-42
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• 2003

The KSR-3 magnetometers consist of the fluxgate magnetometer (MAG/AIM) for acquiring the rocket flight attitude information, and the search-coil magnetometer (MAG/SIM) for the observation of the Earth's magnetic fluctuations. The position (latitude, longitude, and height) and flight condition (the transformation angle) of the rocket is measured after the data based on these two magnetometers are compared with IGRF The gap in the vector of magnetic field between the position of the launching point and an impact point is taken into account in data reduction. Angular variation of pitch, yaw, and roll can be researched when the data is applied to the coordinate system of the rocket.

• Journal of Energy Engineering
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• v.24 no.2
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• pp.167-173
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• 2015

This paper attempts to estimate the electricity demand function in Korea with quarterly data of average temperature, GDP and electricity price over the period 2005-2013. We apply lagged dependent variable model and ordinary least square method as a robust approach to estimating the parameters of the electricity demand function. The results show that short-run price and income elasticities of the electricity demand are estimated to be -0.569 and 0.631, respectively. They are statistically significant at the 1% level. Moreover, long-run income and price elasticities are estimated to be 1.589 and -1.433, respectively Both of results reveal that the demand for electricity is price- and income-elastic in the long-run. The relationship between electricity consumption and temperature is supported by many of references as a U-shaped relationship, and the base temperature of electricity demand is about $15.2^{\circ}C$. It is shown that power of explanation and goodness-of-fit statistics are improved in the use of the lagged dependent variable model rather than conventional model.