• Korean Journal of Remote Sensing
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• v.22 no.5
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• pp.433-437
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• 2006

SAR image is not dependent on the weather condition and Sun's electromagnetic energy. But geometric distortions exist in almost all radar image, it need to be correction. The Radarsat-1 SAR images are used to monitoring of moisture acquired in May 1/1998 and May 25/1998. Radarsat-1 C band data is sensitive on moisture condition. Study area is located in Non-san site. It is made up almost agricultural area and a little of forest area. In May, Rice-planting is started in the midland of Korea. So moisture condition is undergoing many changes. Forest area need to be terrain effect removal for accurately results because it is included in layover, shadow, and so on. Results of land-cover moisture condition map are useful tool for fields of agriculture, forestry industry, and disaster.

• Kyungpook Mathematical Journal
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• v.49 no.2
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• pp.349-353
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• 2009

In this paper we consider some coefficient estimates in the subclass $SL^*$ of strongly starlike functions defined by a certain geometric condition.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.22 no.1
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• pp.45-52
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• 2004

It can be classified in various methods to get the geoidal heights. It can be achieved geometric geoidal heights if we do GPS surveying in leveling point. The aims of this paper are calculation of geometric geoidal heights using GPS/leveling data in study area and evaluation of the global and local geoid models in and around Korean peninsula. For this study, study area was selected in the leveling line from Kunsan to Chonju city and GPS surveying was accomplished in the leveling line. And, also spherical harmonic analysis was made on the three global geopotential models, OSU91A, EGM96, EGM96m under same condition. Then the differences were calculated between geometric geoidal heights and geoidal heights of 3 geopotential models, KOGD2002 which was Korean gravimetric geoid model. The results shows that EGM96m is the best model because the differences between geoidal heights of E6M96m and geometric geoidal heights of GPS/Leveling data appear the smallest value among them.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.33 no.4
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• pp.1611-1617
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• 2013

Information about trafficability or the condition of road with regard to its being traveled over by vehicles is one of the most critical factors for roadway operation in winter. Specifically, when traveling on snowy or icy surfaces, the traction force varies per vehicle type including tire types, geometric characteristics of roads, and conditions of road surfaces. In general, front-wheel drive or four-wheel drive vehicles have better traction performance on snowy or icy surface than rear-wheel drive vehicles, and the latter type vehicle causes more serious traffic congestion when there is unexpected snowfall. Thus, traffic information regarding trafficability with respect to vehicle types, geometric characteristics of roadway sections, and roadway surface conditions can provide a foundation to make a decision whether to use the associated roadway sections for roadway operators as well as users. Based on the preceding premise, the objective of this study is to present a methodology for developing a trafficability index with respect to vehicle types, geometric characteristics of roadway sections, and roadway surface conditions.

• Transactions of the Korean Society of Mechanical Engineers
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• v.15 no.1
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• pp.61-68
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• 1991

The system such as railway bridge can be modelled as the restrained beam with intermediate supports. This kind of structures are subject to the moving load, which has a great effect on dynamic stresses and can cause sever motions, especially at high velocities. Therefore, to analyze the dynamic characteristics of the system due to the moving load is very important. In this paper, the governing equation of motion of a restrained beam subjected to the moving load is derived by using the Hamilton's principle. The orthogonal polynomial functions, which are trial functions and satisfying the geometric and dynamic boundary conditions, are obtained through simple procedure. The dynamic response of the system subjected to the moving loads is obtained by using the Galerkin's method and the numerical time integration technique. The numerical tests for various constraint, velocity and boundary conditions were preformed. Furthermore, the effects of mass of the moving load are studied in detail.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.20 no.2
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• pp.481-487
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• 1996

A snapping-beam microswitch has been designed, fabricated and tested. From a design analysis, necessary and sufficient conditions for a snap-through switching fouction have been derived for a clamped shallow beam. The necessary condition has resulted in a geometric relation, in which the ratio of beam thickness to initial beam deflection plays a key role in the snapping ability. The sufficient condition for the snapping action has been obtained as a function of the inertia force due to applied acceleration, and the electrostatic force, adjustable by an inter-electrode voltage. For experimental investigations, a set of microbeams of silicon dioxide/$P^+$silicon bimorphs have been fabricated. Geometric size and mechanical behavior of each material film have been measured from on-chip test structures. Estimated and measured characteristics of the fabricated devices are compared.

• Journal of radiological science and technology
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• v.23 no.1
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• pp.13-19
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• 2000

We have presented with the "A study on overexposure rate according to over-density in chest X-ray radiography(I)" last year. In this report, We could calculate the entrance skin dose from chest X-ray film density the formula $I_0=Ix/e^{-{\mu}x}{\times}mG$, (mG is Bucky factor) was used to deliver the skin dose. At that time, There was two problems that the Bucky factor from maker was not equal to field experience and the field size influenced on the Attenuation Rate. The experiment of Bucky factor was done from film method and retried the Attenuation Rate of Acryle phantom according to Good & Poor geometry. As the results, The Bucky factor from maker higher than in this experiments $30{\sim}40%$. The Attenuation Rate in good geometric condition brings about a little alteration compare with poor geometric condition. In the field experiment, we could get the chest image with very low entrance skin radiation dose $29.3{\mu}Sv$, especially with air gap methode, the entrance skin dose was detected $10{\mu}Sv$.

• Communications for Statistical Applications and Methods
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• v.13 no.3
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• pp.777-786
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• 2006

Two factorial designs with quantitative factors are called geometrically equivalent if the design matrix of one can be transformed into the design matrix of the other by row and column permutations, and reversal of symbol order in one or more columns. Clark and Dean (2001) gave a sufficient and necessary condition (which we call the 'gCD condition') for two symmetric factorial designs with quantitative factors to be geometrically equivalent. This condition is based on the absolute value of the Euclidean(or Hamming) distance between pairs of design points. In this paper we extend the gCD condition to asymmetric designs. In addition, a modified algorithm is applied for checking the equivalence of two designs.

• Proceedings of the KSME Conference
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• 2000.04b
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• pp.548-554
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• 2000

The aim of this paper is to understand the time averaged pressure distributions in a high-speed centrifugal compressor channel diffuser at design and off-design flow rates. Pressure distributions from the impeller exit to the channel diffuser exit are measured and discussed far various flow rates from choke to near surge condition, and the effect of operating condition is discussed. The strong non-uniformity in the pressure distribution is obtained over the vaneless space and semi-vaneless space caused by the impeller-diffuser interaction. As the flow rate increases, flow separation near the throat, due to large incidence angle at the vane leading edge, increases aerodynamic blockage and reduces the aerodynamic flow area downstream. Thus the minimum pressure location occurs downstream of the geometric throat, and it is named as the aerodynamic throat. And at choke condition, normal shock occurs downstream of this aerodynamic throat. The variation in the location of the aerodynamic throat is discussed.

• Bulletin of the Korean Mathematical Society
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• v.48 no.3
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• pp.523-537
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• 2011

A receiver operating characteristic (ROC) curve plots the true positive rate of a classier against its false positive rate, both of which are accuracy measures of the classier. The ROC curve has several interesting geometrical properties, including concavity which is a necessary condition for a classier to be optimal. In this paper, we study the nonparametric maximum likelihood estimator (NPMLE) of a concave ROC curve and its modification to reduce bias. We characterize the NPMLE as a solution to a geometric programming, a special type of a mathematical optimization problem. We find that the NPMLE is close to the convex hull of the empirical ROC curve and, thus, has smaller variance but positive bias at a given false positive rate. To reduce the bias, we propose a modification of the NPMLE which minimizes the $L_1$ distance from the empirical ROC curve. We numerically compare the finite sample performance of three estimators, the empirical ROC curve, the NMPLE, and the modified NPMLE. Finally, we apply the estimators to estimating the optimal ROC curve of the variance-threshold classier to segment a low depth of field image and to finding a diagnostic tool with multiple tests for detection of hemophilia A carrier.