• Journal of Advanced Marine Engineering and Technology
• /
• v.38 no.8
• /
• pp.981-994
• /
• 2014

Density currents formed by buoyancy discharges from rivers are numerically studied using non-dimensional two layer model including Coriolis acceleration, bottom stress, interfacial friction. Some typical numbers such as Froude number, densimetric Froude number and Kelvin number are obtained and some characteristic scales are defined as a result of non-dimensionalization of the governing equations. Besides the Coriolis effect, the configurations of bottom topography, bottom friction coefficient and interfacial friction are found to significantly affect the propagation of the warm water plume. Frontal position can fastly propagate in the case of large density difference between the two layers and small interfacial friction. Left side boundary current is easily formed under the small interfacial friction. With large Kelvin number, both right and left side boundary currents are formed. Wave-like disturbances and eddies are easily formed under the high Froude number.

• Communications of the Korean Mathematical Society
• /
• v.15 no.4
• /
• pp.697-706
• /
• 2000

If an arithmetic progression F of length 2n and the number k with 2k$\leq$n are give, can we find two monic polynomials with the same degrees whose set of all zeros form F such that both the number of bad pairs and the number of nonreal zeros are 2k? We will consider the case that both the number of bad pairs and the number of nonreal zeros are two. Moreover, we will see the fundamental relation between the number of bad pairs and the number of nonreal zeros, and we will show that the polynomial in x where the coefficient of x(sup)k is the number of sequences having 2k bad pairs has all zeros real and negative.

• Nuclear Engineering and Technology
• /
• v.33 no.6
• /
• pp.585-595
• /
• 2001

A series of experiments have been carried out to investigate the effects of non-condensable gas on the direct contact film condensation of vapor mixture under an adiabatic wall condition. The average heat transfer coefficient of the direct contact condensation was obtained at the atmospheric pressure with four main parameters ; air-mass fraction, mixture velocity, film Reynolds number, and the degree of water film subcooling having an influence on the condensation heat transfer coefficient. With the analysis of 88 experiments, a correlation of the average Nusselt number for direct contact film condensation of steam/air mixture at an adiabatic vertical wall was proposed as functions of film Reynolds number, mixture Reynolds number, air mass fraction, and Jacob number. The average heat transfer coefficient for steam/air mixture condensation decreased significantly while air mass fraction increased. The average heat transfer coefficients also decreased as the Jacob number increased, and were scarcely affected by the film Reynolds number below a mixture Reynolds number of about 245,000.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• 2001.10a
• /
• pp.403-406
• /
• 2001

Number Portability means that one can use his original telephone number when he change telephone service provider, region and the kind of service. It is service provider portability which retain same number when changed the service provider. It is location portability which retain same number when changed the geographic location. It is service portability which retain same number when changed the service type. Revision of INAP(Intelligent Network Application Part) is essential part to provide number portability In this paper, we present the changed part of INAP to provide number part.

• The Korean Journal of Zoology
• /
• v.30 no.4
• /
• pp.379-386
• /
• 1987

Karyotype of the ricessh Orygias latipes (Temminck et Schlegel) was investigated using 151 specimens of eleven populations in the southern Korea. Based on the karyotype analysis, two distinct chromosomal groups were found. One group, occurring in the Kum River, the Mankyong River, the Dongjin River, the Ysngsan River and the SEmjin River had a diploid chromosome number of 46 and arm number of 70, which contained one pair of "large" metacentric chromosomes. The other group, occurring in the Tamjin River, the Hyongsan River andthe all four island populations observed had a diploid chromosome number of 48 and arm number of 68. These results showed that 0. latipes of 6 inland populations was identical with the Chinese population in diploid number, arm number and presence of "large" metacentric chromosome, while the present species of island populations ana populations of the Tamjn R. and Hyongsan R. was similar to the Japanese population in chromosome number and arm number. The karyotype variation in populations indicated that karyotypes will probably provide useful information in studying zoogeography of this species.phy of this species.

• Journal of The Korea Institute of Healthcare Architecture
• /
• v.4 no.6
• /
• pp.67-76
• /
• 1998

The purpose of this study is to estimate the number of the consulation rooms for the O.P.D. in General Hospital. To estimate optimal number of consulation rooms, it has to be considered the factors of population density, neighboring medical supply, condition of location, and the number of bed etc. And the figure of Out-Patients has to be expected as exact as possible. In calculation of consulation rooms, existing hospital planning has been considered only the number of bed, without considering many other factors. According to it, the number of consulation rooms was calculated by consulation and then work out the total number of consulation rooms for the O.P.D.. Therefore this method has been had a lot of problems But. this study considered four factors, and calculated the total number of consulation rooms for O.P.D. and then worked out the number of consulation rooms by O.P.D.

• Journal of Korea Technology Innovation Society
• /
• v.7 no.3
• /
• pp.555-580
• /
• 2004

We analyzed the effect of 6-month lagged number portability policy and introduction of common number among carriers on Korean mobile market. Our result shows that the policy change contributed to both the increase in number of mobile subscribers and decrease in dominant carrier's market share. We found that unified prefix among mobile operators is more effective than the lagged number portability policy. The carriers' profit, however, decreased a lot due to excessive marketing expenditure. We also estimated market shares of carriers up to year 2005 when full number portability policy is adopted. The results show that dominant carrier's monopolistic power will be recovered by the end of 2005 implying government's number policy itself cannot guarantee the effective competition in Korean mobile market.

• Environmental Engineering Research
• /
• v.24 no.2
• /
• pp.318-323
• /
• 2019

Paper focuses on comparison between two different orifice plate configurations (plate number 1 and plate number 2) used as cavitating device in the hydrodynamic cavitation reactor for improving pollutant removal efficiencies. Effect of four different parameters such as hydraulic characteristics (in terms of range of flow rates, orifice velocities, cavitation number at different inlet pressures); cavitation number (in range of 5.76-0.35 for plate number 1 and 1.20-0.35 for plate number 2); inlet pressure (2-8 bars) and reaction time (0 to 60 min) in terms of chemical oxygen demand (COD) removal and chlorpyrifos degradation has been studied and compared. Optimum inlet pressure of 5 bars exists for degradation of pollutants for both the plates. It is found that geometry of orifice plate plays important role in removal efficiencies of pollutant. Results obtained confirmed that orifice plate 1 with configuration of 1.5 mm 17 holes; cavitational number of 1.54 performed better with around 60% COD and 98% chlorpyrifos removal as compared to orifice plate 2 having configuration of 2 mm single hole; cavitational number of 0.53 with 40% COD and 96% chlorpyrifos in 2 h duration time.

• Kyungpook Mathematical Journal
• /
• v.64 no.2
• /
• pp.303-309
• /
• 2024

An imaginary bicyclic biquadratic number field K is a field of the form ${\mathbb{Q}}({\sqrt{-m}},{\sqrt{-n}})$ where m and n are squarefree positive integers. The ideal class number h_K of K is the order of the abelian group I_K/P_K, where I_K and P_K are the groups of fractional and principal fractional ideals in the ring of integers 𝒪_K of K, respectively. This provides a measure on how far is 𝒪_K from being a PID. We determine all imaginary bicyclic biquadratic number fields with class number 5. We show there are exactly 243 such fields.

• Solar Energy
• /
• v.5 no.2
• /
• pp.11-19
• /
• 1985

In this paper, the interface stability not to occur mixing and entrainment between the adjacent layers has been studied in the case of the selective withdrawal of a stratum and the injection in stratified fluid formed by the density difference in a small solar pond. There are stability parameter, Richardson number, Rayleigh number and Froude number as the parameters governing stability in order to measure the interface stability on the stratified fluid. The model which could measure the interface stability on the stratified fluid was the small solar pond composed by 1 meters wide, 2 meters high, and 5 meters long. In order to measure the interface stability on the stratified fluid at the inlet port, the middle section and the outlet port, Richardson number, Rayleigh number, and Froude number involved in the parameters governing the stability were calculated by means of the data resulted from the test of the study on hydrodynamic stability between the convective and nonconvective layers in that solar pond. Richardson number written by the ratio of inertia force to buoyancy force can be used in order to measure the stability on the stratified fluid related to the buoyancy force generated from the injection of fluid. Rayleigh number written by the product of Grashof number by Prandtl number can be used in order to measure the stability of the fluid related to the heat flux and diffusivity of viscosity. Froude number written by the ratio of gravity force to inertia force can be used in order to measure the stability of the nonhomogeneous fluid related to the density difference. As the result of calculating the parameters governing stability, the interface stability on the stratified fluid couldn't be identified below the 70cm height from the bottom of the solar pond, but it could be identified above the 70cm height from it at the inlet port, the middle section and the outlet port. When compared with such the three parameters as Richardson number, Rayleigh number, Froude number, the calculated result was in accord with them at inlet port, the middle section and the outlet port. Henceforth, it is learned that even though any of the three parameters is used for the purpose of measuring the interface stability on the stratified fluid, the result will be the same with them. It is concluded that all the use of Richardson number, Rayleigh number, and Froude number, is desirable and infallible to measure the interface stability on the stratified fluid in the case of considering the exist of the fluid flow and the heat flux like the model of the solar pond.