• 한국신재생에너지학회:학술대회논문집
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• 2005.06a
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• pp.310-313
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• 2005

The conical fluidizing system of a binary mixture of Geldart C powders and Geldart A particles was defined as the conical powder-particle fluidized bed. We used a cold conical powder-particle fluidized bed model having a 0.104m-I.D. and 0.6m-high with an apex angle of $10^{\circ}$ for fluidization of a binary powder-particle mixture of 50 $vol\%$ fine carbon black powders (HI-900L, Korea Carbon Black Co.) and coarse alumina particles $(90{\mu}m)$ under different superficial gas velocities (0-0.1 m/s). The differential bed pressure drop increases with increasing gas velocity, and it goes from zero to a maximum value with increasing or decreasing gas velocity. In the conical fluidized beds of fine powders, demarcation velocities of the partial fluidization, full fluidization, partial defluidization was not observed.

• The Research Journal of the Costume Culture
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• v.10 no.5
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• pp.485-492
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• 2002

The purpose of this study is to classify of the Cone shaped Pendants in old tombs of Three Kingdom States. These Cone shaped Pendants are made of bronze and coated with gold plate or Gold. Each Cone shaped Pendants consists of a Sehwhan(細環) type or Taewhan type, a median part in the form of a several joined small globe, or circular shape, and finally a cone-shared pendant. Cone shaped Pendants is 5 part(A-L A-b, B-1-a, B-1-b, B-2-b type) in according to the styles of the Sehwhan(細環) and Taewhan type and median ornament types. A-a, A-b, B-1-a, B-1-b type was general style that was found in most of the old tombs in Kokuryo, Pacjae, ancient Silla. B-2-b type was excavated from the only Kokuryo tombs.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.20 no.5
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• pp.413-420
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• 2009

We propose a novel feed network for a $2{\times}2$ array antenna to form a sectoral conical beam. The proposed feed network, which is a symmetrical structure, consists of four $90^{\circ}$ hybrids, a crossover, and four $90^{\circ}$ delay lines. To verify the performance of the feed network a $2{\times}2$ array antenna and the feed network are fabricated on a microstrip structure, and the radiation patterns are measured at the center frequency of 2.57 GHz. The maximum radiation is measured at the $45^{\circ}$ elevation angle and at the $45^{\circ}$, $135^{\circ}$, $225^{\circ}$, and $315^{\circ}$ azimuth angles depending on the choice of the input port of the feed network.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.39 no.11
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• pp.861-869
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• 2015

In this study, wall to bed heat transfer and hydrodynamic characteristics in a conical fluidized bed combustor was investigated using computational fluid dynamics method. A two-fluid Eulerian-Eulerian model was used with applying the kinetic theory for granular flow(KTGF). The effects of the two drag models, Gidaspow and the Syamlal-O'Brien model, different inlet velocities($1.4U_{mf}{\sim}4U_{mf}$) and different particle sizes on the hydrodynamics and heat transfer were studied. The results showed that the hydrodynamic characteristics such as bed expansion ratio and pressure drop were not affected significantly by the drag models. But the heat transfer coefficient was different for the two drag models, especially at lower gas inlet velocities and small particle sizes.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.15 no.6
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• pp.3370-3375
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• 2014

MILD combustion is a highly favored technology for solving the trade-off relation between high thermal efficiency and low pollutant emissions. The system has low NOx concentration in high temperature combustion by recirculating the combustion gas, as well as improving the thermal efficiency by making the internal temperature in a combustion furnace uniform. This study describes the combustion characteristics of a conical MILD combustor in a laboratory-scale furnace by adjusting the equivalence ratio with the fuel gas flow rate while maintaining a constant air flow rate of the furnace. The MILD regime in the furnace is well characterized and the in-furnace temperature and emissions were predicted, respectively, for the range of equivalence of 0.69 - 0.83. For the range of equivalence ratios, this study confirmed the existence of a stable flame region that has an approximately $300^{\circ}C$ temperature difference between the maximum flame temperature region and main reaction region.

• Korean Journal of Optics and Photonics
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• v.7 no.4
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• pp.434-439
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• 1996

To investigate influence of the incident beams which have the truncated Gaussian amplitude and of the shapes of bump on read-out signal is an optical disc, and the point spread function on bump, the scalar diffraction theory is used in this paper. We consider the truncated Gaussian amplitudes which are $\sigma$=0, 0.5, 1.5, and 2.5, the height of bump which is given by $n{\Delta}_0={\lambda}/4$, and the phase height of bump which is then given by ${\Phi}_0={\pi}$. We also consider the shapes of the bump which are a rectangular shape, a frustoconical shape, and a conical shape. It is shown that as the truncation of incident beam reduces the radius of central spot on bump decreases, the maximum value of read-out signal increases, and that the size of bump decreases. From these results, we get better read-out signal and the reduced cross-talk in optical disc when the truncation of incident beam reduces. Therefore a laser beam having less truncated Gaussian amplitude may useful for an actual optical disc.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.25 no.5
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• pp.713-721
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• 2001

Characteristics of the conical vortices on the roof corner of a rectangular prism have been investigated by using a PIV(Particle Image Velocimetry) technique. The Reynolds number based on the free stream velocity and the height of the model was 5.3$\times$10$^3$. The mean, instantaneous velocity vector fields, vorticity fields, and turbulent kinetic energy distribution were measured for two different angles of attack, 30$^{\circ}$and 45$^{\circ}$. The PIV measurements clearly observed not only the conical main vortex and the secondary vortex but also the tertiary vortex which is firstly reported in this paper. Asymmetric formation of the corner vortex for the case of 30$^{\circ}$angle of attack produces relatively the high magnitude of vorticity and turbulent kinetic energy around the bigger vortex which generates the peak suction pressure on the roof. Fairly symmetric features of the roof vortex are observed in the case of 45$^{\circ}$angle of attack, however, the dynamic characteristics are proved to be asymmetric due to the rectangular shape of the roof.

• The Journal of Engineering Geology
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• v.8 no.1
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• pp.25-34
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• 1998

It is not easy to understand exact soil properties, because soil is nonhomogeneous and anisotropic. There are raany inefficient cases in aspect of time and economy in site survey. So this study tried to analyze the correlation of cone resistance and seismic velocity in order to present an efficient method in ground investigation. A cone penetrometer is frequently used to investigate soil properties, which are especially fit to investigate coastal soft ground. A portable cone penetrometer was used in this research. A portable cone penetrometer has an advantage in investigating the state of soil swiftly and is convenient to manipulate. Also, seismic prospecting is one of the most PoPular methods among geophysical prospecting methods in the estimation of ground properties and its usage is continuously increasing in the survey of soft ground Cone resistance makes a regular group according to stratum in each depth. The results of seismic prospecting show a tendency to have a certain coherence according to the boundary of straturft Therefore, cone resistance and seisrnic prospecting have considerable relations that rnay irnprnve the efficiency of ground investigation.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.26 no.2
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• pp.278-287
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• 2002

The objective of the paper was to calculate the pressure drop and to investigate the recirculation region of the conical orifices used in Kwang-yang Iron & Steel Company. The flow field with water used as a working fluid was the turbulent flow for Reynolds number of 2$\times$10$^4$. The effective parameters fur the pressure drop and the recirculation region were the conical orifice\`s inclined angle ($\theta$) against the wall, the interval(S) between orifices, the relative angle of rotation($\alpha$) of the orifices, the shape of the orifice's hole(circle, rectangle, triangle) having the same area, the number(N) of the orifice's holes having the same mass flow rate, and the thickness(t) of the orifices. It was fecund that the shape of the orifice's hole, the number of the orifice's holes and the thickness of the orifice affected the total pressure drop a lot and that the conical orifice's inclined angle against the wall, the relative angle of rotation of the orifices, the number of the orifice's holes and the thickness of the orifices affected the center location of the recirculation region. The PISO algorithm with FLUENT code was employed to analyze the flow field.

• Korean Journal of Plant Resources
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• v.12 no.1
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• pp.50-61
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• 1999

The leaf morphological and anatomical characters about 17 taxa of Aster and its allied taxa were investigated to estimate taxonomic values. Leaf shapes of the treated taxa were divided into five types; elliptic, spathulate, lanceolate, linear, ovatodeltoid. These types were fixed in same taxa, but variable among different taxa, therefore useful as taxonomic character. Leaf margins were divided into four types; entire, serrate, dentate, incised, these types were invariable in most taxa, but variable among individual in same taxa such as Kalimeris incise, Aster spathulifolius. The size and shape of leaf epidermal cell, the size and distributional numbers per 10$\textrm{mm}^2$ of stomata, deposit feature of cuticle were not distinguished clearly from treated taxa, but presence of stomata on adaxial surface, size and distributional numbers per 10$\textrm{mm}^2$ of stomata were useful taxonomic characters in some taxa such as Gymnaster koraiensis, Aster altaicus var. uchiyamae, Aster tripolium, Heteropappus arenarius. The leaf trichomes were divided into five types by basic form, sculpturing on their outer surface and cell arrangement; uniseriate granulate conical type, uniseriate psilate conical type, uniseriate psilate filiform type, globular type, biseriate vesicular capitate type. In spite of various habitat, basic morphology of trichomes were not changed, therefore, it was thought to be good taxonomic character.