• The Pure and Applied Mathematics
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• v.23 no.3
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• pp.309-317
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• 2016

As a generalization of an inflection point, we consider a point P on a smooth plane curve C of degree m at which another curve C' of degree n meets C with high intersection multiplicity. Especially, we deal with the existence of two curves of degree m and n meeting at the unique point.

• Communications of the Korean Mathematical Society
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• v.38 no.4
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• pp.1281-1298
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• 2023

Let (M^2m, 𝜑, g) be a B-manifold. In this paper, we introduce a new class of metric on (M^2m, 𝜑, g), obtained by a non-conformal deformation of the metric g, called a generalized Berger-type deformed metric. First we investigate the Levi-Civita connection of this metric. Secondly we characterize the Riemannian curvature, the sectional curvature and the scalar curvature. Finally, we study the proper biharmonicity of the identity map and of a curve on M with respect to a generalized Berger-type deformed metric.

• The Bulletin of The Korean Astronomical Society
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• v.36 no.1
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• pp.28.1-28.1
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• 2011

We observed the transiting exoplanet, TrES-2b, with 1.5m telescope at Maidanak Observatory in Uzbekistan. We observed TrES-2 system for six nights, which contained two orbital periods of the planet. Therefore, we obtained the entire light curve of TrES-2b, which covered not only the whole primary transit containing both ingress and egress part, but also non-transit region. We used both R and Y band filters. Especially, Y filter is used first for transit observation and covers relatively longer wavelength ($1.02{\mu}m$ of center wavelength), to provide the light curve less affected by limb darkening. By fitting best model light curve for the obtained one, we determined these observables, transit depth, transit length, and planet's orbital period, which led to the determination of five physical parameters, stellar radius R*, stellar mass M*, inclination i, semi-major axis a, and planetary radius Rp. We will discuss of these results.

• Journal of the Korean Mathematical Society
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• v.58 no.6
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• pp.1485-1500
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• 2021

A curve is rectifying if it lies on a moving hyperplane orthogonal to its curvature vector. In this work, we extend the main result of [Chen 2017, Tamkang J. Math. 48, 209] to any space dimension: we prove that rectifying curves are geodesics on hypercones. We later use this association to characterize rectifying curves that are also slant helices in three-dimensional space as geodesics of circular cones. In addition, we consider curves that lie on a moving hyperplane normal to (i) one of the normal vector fields of the Frenet frame and to (ii) a rotation minimizing vector field along the curve. The former class is characterized in terms of the constancy of a certain vector field normal to the curve, while the latter contains spherical and plane curves. Finally, we establish a formal mapping between rectifying curves in an (m + 2)-dimensional space and spherical curves in an (m + 1)-dimensional space.

• Journal of Korean Port Research
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• v.12 no.1
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• pp.131-143
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• 1998

This paper presents derivation of stage-discharge curve for Yangsan river. To derivate of stage-discharge lationship is one of the essential research areas in the water resource field. It provides reliable data a long term planning and hydrologic quantity on water resource development by quantitative analysis. The rating curve derivated through 15 discharge-observation on Yangsan river basin in 1997 has been estimated Q=1283.0262-1553.3158H+477.2702H2. According to the rating curve, the highest water level 2.6m, the limited water-level should be bound to the maximum of 2.6m. Before this research, stage-discharge curve of Yangsan river has not been developed, and only 15 discharge observation(hydrometry) has been carried out though this research. Therefore it seems necessary to collect observation data through a long term process to obtain a reliable rating curve equation.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.51 no.4
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• pp.362-368
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• 2006

A pot experiment was conducted to investigate the effects of soil burial depth on seedling emergences of rice (Oryza sativa) and Echinochloa spp. and to model such effects for mathematical prediction of seedling emergences. When the Gompertz curve was fitted at each soil depth, the parameter C decreased in a logistic form with increasing soil depth, while the parameter M increased in an exponential form and the parameter B appeared to be constant. The Gompertz curve was combined by incorporating the logistic model for the parameter C, the exponential model for the parameter M, and the constant for the parameter B. This combined model well described seedling emergence of rice and Echinochloa species as influenced by soil burial depth and predicted seedling emergence at a given time after sowing and a soil burial depth. Thus, the combined model can be used to simulate seedling emergence of crop sown in different soil depths and weeds present in various soil depths.

• The Korean Journal of Pharmacology
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• v.8 no.2
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• pp.55-61
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• 1972

Superprecipitation of actomyosin has been considered to be an in vitro model of the muscle contraction. The superprecipitation and ATPase activity (which supplies the energy for contraction) are influenced by several factors which are the large amount of changes in ionic strength, Mg and ATP concentrations. But those behaviors are found to be promptly influenced by the change in a small range of calcium concentration which can be controlled by the cellular function of muscle physiologically only in the presence of the modullatory proteins, tropomyosin and troponin. In order to elucidate the precise roles of calcium in the muscle contraction and relaxation, the effects of calcium on the actin- myosin interaction was observed in the presence of tropomyosin and troponin using the superprecipitation system. The results are summarized as follows: 1. EGTA (glycol ether diaminetetraacetic acid)prolonged the initiation of the superprecipitation of natural actomyosin. 2. Superprecipitation curve was declined by adding EGTA at the time when tile curve reached the half- maximum. The degree of declining was proportional to the amount of EGTA added. Especially, upon adding 0.25 mM EGTA the curve was lowered to the level before the protein superprecipitated. But addition of EGTA did not affect the curve after attaining the maximum. 3. Superprecipitation of Perry myosin B was not affected by EGTA added both before and during the course of the reaction. 4. Tropomyosin did not change the response of Perry myosin B to EGTA added at any time of the reaction. 5. Troponin also did not change the response of Perry myosin B to EGTA. 6. Both tropomyosin and troponin together rendered the Perry myosin B to obtain the same response as natural actomyosin to EGTA. 7. It was concluded that actin-myosin interaction was influenced by the minute change of calcium concentration only in the presence of both tropomyosin and troponin. We could reproduce the contraction and relaxation of the muscle in vitro under the presence of ATP by changing the calcium concentration.

• The Pure and Applied Mathematics
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• v.28 no.4
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• pp.399-411
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• 2021

We consider a Weierstrass semigroup at a generalized flex on a smooth plane curve. We find the candidates of a Weierstrass semigroup at a 2-flex of higher multiplicity on a smooth plane curve of degree d ≥ 5, and give some examples to show the existence of them.

• Korean Journal Plant Pathology
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• v.13 no.1
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• pp.37-45
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• 1997

Disease incidence (DI), pre-emergence damping-off (PDO), days until the first symptom appeared (DUS), disease progress curve (DPC), and area under disease progress curve (AUDPC) were investigated in vivo after sowing ginseng seeds in each of 37 ginseng-cultivated soils which were sampled from 4 regions in Korea. Non linear fitting parameters, A, B, K and M, were estimated from the Richards' function, one of the disease progress models, by using the DI at each day from the bioassay. Inter- and intra-relationships between disease variables and stand-missing rate (SMR) in fields were investigated by using the simple correlation analysis. Disease variables of the root rot were divided into two groups: variables related to disease incidence, e.g., DI, AUDPC and A parameter, and variables related to disease progress, e.g., B, K and M parameters. DI, AUDPC, and DUS had significant correlations with SMR in ginseng fields, and then it showed that the disease development in vivo corresponded with that in fields. Soil samples could be separated into 3 and 4 groups, respectively, on the basis of the principal component 1 (PC1) and the principal component 2 (PC2), which were derived from the principal component analysis (PCA) of Richards' parameters, A, B, K and M. PC1 accounted for B, K and M parameters, and PC2 accounted for A parameter.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.29 no.4
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• pp.247-259
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• 1993

The fishing experiment was carried out by the training ship Saebada in order to analyse the mesh selectivity for trawl cod-end, in the Southern Korea Sea and the East China Sea from June. 1991 through August, 1992. The trawl cod-end used in this experiment has the trouser type of cod-end with cover net. and the mesh selectivity was examined for the five kinds of the opening of mesh in its cod-end part. A total of 163 hauls, of which having mesh size 51.2mm ; A 89, 70.2mm ; B 54, 77.6mm ; C 55, 88.0mm ; D 52 and 111.3mm ; E 20 were used respectively. Selection curves and selection parameters were calculated by using a logistic function, S=1/(1+exp super(-(aL+b)) ). The mesh election master curves were estimated by S=1/(1+exp super(-[a(L/M)+$\beta$]) ). and the optimum mesh size were calculated with (L/M) sub(50) of master curve. In these cases 'a' and '$\alpha$' are slope, 'b' and '$\beta$' are intercept. 'L' is body length of the target species of fishes, 'M' is the mesh size, and 'S' denotes mesh selectivity. In this report, the four species of compressed form fishes were taken analized according to fish shape, and 'S' denotes mesh selectivity. In this report, the four species of compressed form fishes were taken analized according to fish shape, and the results obtained are summarized as follows: 1. Red seabream Pagrus major(Temminct et Schlegel) and yellow porgy Dentex tumifrons(Temminct et Schlegel) ; Selection rate in each mesh size of A, B, C, D and E were 99.7%, 97.5%, 91.4%, 76.7% and 57.8% respectively. Selection parameters 'a' and 'b' of mesh sizes C, D and E were 2.65 and -28.62, 4.40 and -77.73, 2.31 and -46.99, and their selection factors were 1.39, 2.10, 1.83 respectively. Selection parameters of master curve '$\alpha$' and '$\beta$' were 3.05 and -5.65 respectively, and (L/M) sub(50) was 1.85. The optimum mesh size of Red seabream was 141mm. 2. Filefish Thamnaconus modestus (Gunther) ; Selection rate in each mesh size of A, B, C, D and E were 99.6%, 98.3%, 91.2%, 80.0% and 48.6% respectively. Selection parameters 'a' and 'b' of mesh sizes C, D and E were 5.82 and -55.10, 2.92 and -36.90, 3.91 and -63.09, and their selection factors were 1.35, 1.44, 1.45 respectively. Selection parameters of master curve '$\alpha$' and '$\beta$' were 3.02 and -4.32 respectively, and (L/M) sub(50) was 1.43. The optimum mesh size was 129mm. 3. Target dory Zeus faber Valenciennes ; Selection rate in each mesh size of A, B, C, D and E were 99.7%, 100%, 83.2%, 91.6% and 65.0% respectively. Selection parameters 'a' and 'b' of mesh sizes C, D and E were 3.85 and -32.46, 4.19 and -57.38, 2.45 and -40.03, and their selection factors were 1.09, 1.56, 1.47 respectively. Selection parameters of master curve '$\alpha$' and '$\beta$' were 2.64 and -3.53 respectively, and (L/M) sub(50) was 1.34. The optimum mesh size was 127mm. 4. Butterfish Psenopsis anomala (Temminct et Schlegel) ; Selection rate in each mesh size of A, B, C, D and E were 99.2%, 34.1%, 46.5%, 14.3% and 2.4% respectively. Selection parameters 'a' and 'b' of mesh sizes B, C and D were 5.35 and -71.70, 5.07 and -69.25, 3.31 and -62.06 and their selection factors were 1.91, 1.75, 2.13 respectively. Selection parameters of master curve '$\alpha$' and '$\beta$' were 3.16 and -6.24 respectively, and (L/M) sub(50) was 1.98. The optimum mesh size was 71mm.