• Journal of Positioning, Navigation, and Timing
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• v.9 no.3
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• pp.221-227
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• 2020

In this paper, the Iterated Consider Extended Kalman Filter (ICEKF) is proposed for bearing-only localization of GNSS interference to improve the estimation performance and filter consistency. The ICEKF is an extended version of Consider KF (CKF) for Iterated EKF (IEKF) to consider an effect of bearing measurement bias error to filter covariance. The ICEKF can mitigate the EKF divergence problem which can occur when linearizing the nonlinear bearing measurement by a large initial state error. Also, it can mitigate filter inconsistency problem of EKF and IEKF which can occur when a weakly observable bearing measurement bias error state is not included in filter state vector. The simulation result shows that the localization error of the ICEKF is smaller than the EKF and IEKF, and the Root Mean Square (RMS) estimation error of ICEKF matches the covariance of filter.

• Proceedings of the KSME Conference
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• 2000.11b
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• pp.692-697
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• 2000

Recently, Flat flame burners are hilighted in high-load burners. Our study contains flow field analysis of a flat flame burner. In this paper, We analyzed the direction and magnitude of the velocity in a round tile type burner with swirl angles, $10^{\circ},\;30^{\circ},\;50^{\circ}$. In the case of swirl angle $10^{\circ}$, because axial momentum is larger than radial momentum, Recirculation region was weakly developed. In the case of swirl angle $50^{\circ}$, Flow in front of the tile is distributed for radial direction. And Recirculation region is large. So, We expect that the radiation can be transmitted from tiles and the recirculation region may cause $NO_x$ reduction.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.20 no.2
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• pp.605-615
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• 1996

Laminar flows in which mixing and chemical reactions take place between parallel streams of reactive species are studied numerically. The governing equations for laminar flows are from two-dimensional compressible boundary-layer equations. The chemistry is a finite rate single step irreversible reaction with Arrhenius kinetics. Ignition, premixed flame, and diffusion flame regimes are found to exist in the laminar reacting mixing layer at high activation energy. At high Mach numbers, ignition occurs earlier due to the higher temperatures in the unburnt gas. In diffusion regimes, property variations affect the laminar profiles considerably and need to be included when there are large temperature differences. The maximum temperature of a laminar reacting mixing layer is almost linear with the adiabatic flame temperature at low heat release, but only weakly at high heat release.

• Natural Product Sciences
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• v.9 no.2
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• pp.64-67
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• 2003

The purgative activities of Whangryunhaedoktang (WT), Chunghyuldan (CD) and Rhei Rhizoma were measured to choose herbal formulae available for stroke patients suffering from constipation. When the laxative activity of Rhei Rhizoma and CD (the same dose as Rhei Rhizoma) compared, Rhei Rhizoma was more potent than CD. WT contained Gardeniae Fructus, which has been used as a laxative, as a ingredient. Nevertheless, WT did not show the purgative activity. WT and CD did not stimulate the transportation of small intestine. However, CD weakly stimulated the transportation of large intestine than Rhei Rhizoma. Accordingly, we believe that CD can be used as a useful purgative for stroke patients with constipation.

• Bulletin of the Korean Chemical Society
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• v.34 no.11
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• pp.3372-3376
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• 2013

The kinetic studies on the reactions of ethyl methyl (2) and ethyl propyl (4) chlorothiophosphates with X-pyridines have been carried out in acetonitrile at $35.0^{\circ}C$. The free energy correlations with X show biphasic concave upwards with a break point at X = H (2) and 3-Ph (4), respectively. A stepwise mechanism with a rate-limiting leaving group expulsion from the intermediate is proposed based on the magnitudes of selectivity parameters for both substrates. The considerably large values of ${\beta}_X$ = 1.50(2) and 1.44(4) with strongly basic pyridines and relatively small values of ${\beta}_X$ = 0.43(2) and 0.36(4) with weakly basic pyridines are interpreted as a change of the attacking direction of the X-pyridines from a frontside to a backside attack toward the chloride leaving group.

• Honam Mathematical Journal
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• v.42 no.1
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• pp.93-103
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• 2020

This article concerns a property of Abelain π-regular rings. A ring R shall be called right quasi-DR if for every a ∈ R there exists n ≥ 1 such that C(R)aⁿ ⊆ aR, where C(R) means the monoid of regular elements in R. The relations between the right quasi-DR property and near ring theoretic properties are investigated. We next show that the class of right quasi-DR rings is quite large.

• Journal of applied mathematics & informatics
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• v.23 no.1_2
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• pp.419-433
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• 2007

Medial axis transform (MAT) is very sensitive to noise, in the sense that, even if a shape is perturbed only slightly, the Hausdorff distance between the MATs of the original shape and the perturbed one may be large. Recently, Choi et al.(2002) showed that MAT is stable for a class of 2D domains called weakly injective, if we view this phenomenon with the one-sided Hausdorff distance, rather than with the two-sided Hausdorff distance. In this paper, we extend this result to general 2D domains with natural boundary regularity. We also present explicit bounds for this general one-sided stability of the 2D MAT.

• Animal Systematics, Evolution and Diversity
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• v.37 no.1
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• pp.81-83
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• 2021

Two species of Scopula, S. asthena Inoue, 1943 and S. tenuisocius Inoue, 1942, were newly recorded from Korea. Scopula asthena can be distinguished by the bipectinate male antennae and whitish wings with four blackish dots on each wing. This species is similar to S. superior (Butler, 1878) but differs in the large blackish discal dots on both wings. Scopula tenuisocius can be distinguished by its whitish forewing with light grayish, dentate antemedial line, short-line shaped discal dot and line light grayish, weakly rounded, dentate postmedial line, and whitish hindwing with a blackish discal dot and light grayish, undulating medial lines. Scopula tenuisocius is similar to S. floslactata (Haworth, 1809) but the species can be distinguished by the thinner and blackish subterminal line of the forewing that appears minutely dentate along the line. To date, 41 species of the genus Scopula are known in Korea.

• International Journal of Naval Architecture and Ocean Engineering
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• v.12 no.1
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• pp.297-313
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• 2020

An Arctic Spar is characterized by its conical shape near the waterline. In this case, the nonlinear effects from its irregular hull shape would be significant if there is either a large amplitude floater motion or steep wave conditions. Therefore, in this paper, the nonlinear effects of an Arctic Spar are numerically investigated by introducing a weakly nonlinear time-domain model that considers the time dependent hydrostatic restoring stiffness and Froude-Krylov forces. Through numerical simulations under multiple regular and irregular wave conditions, the nonlinear behavior of the Arctic Spar is clearly observed, but it is not shown in the linear analysis. In particular, it is found that the nonlinear Froude-Krylov force plays an important role when the wave frequency is close to the heave natural frequency. In addition, the nonlinear hydrostatic restoring stiffness causes the structure's unstable motion at a half of heave natural period.

• Animal Systematics, Evolution and Diversity
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• v.39 no.4
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• pp.322-324
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• 2023

The hepialid species, Korscheltellus lupulina (Linnaeus) is newly recorded from Korea. A female specimen of K. lupulina was collected on Jeju Island, southern Korea. This species can be distinguished by the whitish linear marking on the postmedian and dorsum of the forewing but these markings are often unseen in females. The female genitalia can be diagnosed by the semi-rounded ninth abdominal tergum, a pair of semi-rounded ninth abdominal sternum with weakly produced, semi-rounded central plate-shaped medial region, a pair of narrow band-shaped subanal plates, the short, thin ductus bursae, and the large, ball-shaped corpus bursae without a signum. Currently, there are four genera and five species of the Hepialidae distributed in Korea.