• The Pure and Applied Mathematics
• /
• v.18 no.4
• /
• pp.369-377
• /
• 2011

In this article, we study generalized slant cylindrical surfaces (GSCS's) with pointwise 1-type Gauss map of the first and second kinds. Our main results state that GSCS's with pointwise 1-type Gauss map of the first kind coincide with surfaces of revolution with constant mean curvature; and the right cones are the only polynomial kind GSCS's with pointwise 1-type Gauss map of the second kind.

• The Korean Journal of Ecology
• /
• v.25 no.4
• /
• pp.213-216
• /
• 2002

Main attackers on pine seeds on the forest floor were investigated in Korea. Damage on pine cones begins in early stage of cone formation, especially by squirrel and Korean squirrel. The above animals left Kayak-like hulls of seed on rocks and fallen tree trunk. Field mice also left the same shape of Kayak-like hulls. But birds including doves and peasants left large shreds with longitudinal cracks or seed cup trace. Most of seeds on the leaf litters as well as under the fallen leaf were consumed by field mice and birds. Especially field mice found the seeds under fallen leaves and consumed all of them.

• Journal of the Korean Mathematical Society
• /
• v.56 no.5
• /
• pp.1309-1331
• /
• 2019

We study the homogeneous Dirichlet boundary value problem of generalized Laplacian systems with a singular weight which may not be in $L^1$. Using the well-known fixed point theorem on cones, we obtain the multiplicity results of positive solutions under two different asymptotic behaviors of the nonlinearities at 0 and ${\infty}$. Furthermore, a global result of positive solutions for one special case with respect to a parameter is also obtained.

• Proceedings of the Korean Vacuum Society Conference
• /
• 2015.08a
• /
• pp.235.1-235.1
• /
• 2015

Artificially-engineered materials, whose electromagnetic properties are not available in nature, such as negative reflective index, are called metamaterials (MMs). Although many scientists have investigated MMs for negative-reflective-index properties at the beginning, their interests have been extended to many other fields comprising perfect lenses. Among various kinds of MMs, metamaterial absorbers (MM-As) mimic the blackbody through minimizing transmission and reflection. In order to maximize absorption, the real and the imaginary parts of the permittivity and permeability of MM-As should be adjusted to possess the same impedance as that of free space. We propose a dual-wide-band and polarization-independent MM-A. It is basically a triple-layer structure made of metal/dielectric multilayered truncated cones. The multilayered truncated cones are periodically arranged and play a role of meta-atoms. We realize not only a wide-band absorption, which utilizes the fundamental magnetic resonances, but also another wide-band absorption in the high-frequency range based on the third-harmonic resonances, in both simulation and experiment. In simulation, the absorption bands with absorption higher than 90% are 3.93 - 6.05 GHz and 11.64 - 14.55 GHz, while the experimental absorption bands are in 3.88 - 6.08 GHz and 9.95 - 13.84 GHz. The physical origins of these absorption bands are elucidated. Additionally, it is also polarization-independent because of its circularly symmetric structures. Our design is scalable to smaller size for the infrared and the visible ranges.

• Journal of Korea Foresty Energy
• /
• v.25 no.1
• /
• pp.39-45
• /
• 2006

This study was conducted to understand the biomass and the energy content of 36-year-old Pinus rigida stand planted in Mt. Taehwa, Gwangju-si, Gyeonggi-do, Korea. The total biomass of aboveground was 252.0 ton/ha (65.9% from stemwood, 8.9% from stembark, 20.6% from live branches, 1.5% from current leaves, 2.6% from previous leaves, and 0.5% from cones). Annual net production (ANP) of aboveground was 27.4 ton/ha/yr, and the ratio of stemwood, stembark, live branches, current leaves, and cones to ANP of aboveground total, 56.3%, 6.1%, 19.1%, 13.9%, and 4.6%, respectively. Energy content of aboveground was 5,434 GJ/ha, and annual energy accumulation was 597 GJ/ha/yr. Photosynthetic layer of P. rigida was shown at about 5.2 m in height, and maximum needle amount of crown at 11 to 13 m in height.

• Journal of the Korean Institute of Landscape Architecture
• /
• v.35 no.1 s.120
• /
• pp.48-58
• /
• 2007

The purpose of this study was not only to clearly examine the features of the scenery and visual elements of Oreum (parasitic cones) but also to investigate primary factors in landscape preferences for these cones. This study further attempted to gain basic information for examining the preservation of Oreum in regards to the influence of scenery on the general public. A Multiple Regression Analysis was used for this study for which the independent variable was the area ratio of the fore-, mid-, and background of the view under the feature element and the structure of the scenery at the Oreum. The dependent variables were the preference value, the number of summits, and the highest altitude of the Oreum. All but the highest inclination were positive variables. The area ratio of the Oreum was found to be the most important variable. The area of sky and the area of the distant scenery were shown to be positive explanation variables, while the area to the fore of the view and the area to the middle of the view were shown as negative explanation variable. In the preference for Oreum scenery, which has a high visibility and is clearly outlined against the skyline, it was found that as the hindrance element of visibility near to a visual point or the area ratio increased, the preference for the Oreum scenery decreased.

• Journal of Korean Ophthalmic Optics Society
• /
• v.18 no.2
• /
• pp.187-191
• /
• 2013

Purpose: This study was done to understand the visual system of bat by analyzing the distribution of middle/long (ML) opsin cone photoreceptors in the retina of the greater horseshoe bat. Methods: Experiments have been performed by standard immunocytochemical techniques on retina of the greater horseshoe bat Rhinolophus ferrumequinum. Results: The estimated numbers of ML cones were $27,336{\pm}2,130$ cells and the mean density of them was $7,854{\pm}268cells/mm^2$ among the four retinas. S opsin was appeared a little immunoreactivity in the outer segments of outer nuclear layer of cones. Conclusions: From the well organized spatial distributions of ML opsin and the immunoreactivity of S opsin in the retinas, the greater horseshoe bats have the functions not only reacting in the photopic vision but being able to distinguish the colors.

• Journal of the Korean earth science society
• /
• v.29 no.6
• /
• pp.466-473
• /
• 2008

This study deals with the morphological characteristics and structure of organ fossils of Neocalamites carrerei such as rhizomes, aerial leafy stems, and cones collected in situ from the Amisan Formation of Nampo Group. Judging from the size of some extant Equisetum and paleoclimate of Daedong flora, it is considered that the size of Neocalamites carrerei was probably very large. The cone of Neocalamites takahashii (Kon'no) is closely associated with the leaves of Neocalamites carrerei. It indicates that two organ fossils mentioned above probably belong to the same species. Comparing with very abundant occurrence of aerial leafy stems and rhizomes in the Amisan Formation, cones are very rare. This fact implies that Neocalamites reproduce not only by spore reproduction, but also by asexual reproduction. Neocalamites largely differ in the leaf form and size from Equisetum.

• Proceedings of the Korean Geotechical Society Conference
• /
• 2006.03a
• /
• pp.744-751
• /
• 2006

In case of the Soil Nail System applied to a slope, effects of vibrations from blasting, earthquake and creep of long term behaviors cause reductions of adhesion between grout and soil-nail. There are some reports of nail's pull-out failure by those reasons. In this paper it is suggested that the Cone Nailing System is enable to diminish effects of vibrations and creep. In this study on Cone Nailing System, the cones are installed to each nail by 2m. By such installing cones, the adhesion between nail and grout will increase and the long term creep behavior will decrease. In this study, the centrifuge test is performed to understand the behaviors of the Cone Nail System. For the centrifuge test, the soil tank is 52cm in width, 17cm in length and 35cm in height. In comparison with general soil nail, the centrifuge test of general soil nail(without cone) is performed equally. Additionally, the interface between cone nail and soil through the pull-out test is applied to FLAC 2D version 3.3. and the evaluation of application for the Cone Nail System in slope is performed.

• The Journal of Korean Academy of Prosthodontics
• /
• v.42 no.1
• /
• pp.1-10
• /
• 2004

Statement of problem : Tooth wear is physiological phenomenon. Ninety-seven percent of normal people have tooth wear and about 7% has pathologic teeth wear. If we know the amount of tooth surface loss caused by pathologic tooth wear, we may restore it ideally Purpose : Recently measurement of tooth wear by using 3D scan has been increasing. Therefore, we need to know how accurate 3D scan is. Past accuracy test on 3D scan was about linear change, but as we know that tooth wear is volume change. Thus, the purpose of this study is to know how accurate 3D scan is. Material and Methods : For accuracy test of 3D scanner volume values measured by 3D scanner and micro-balance were compared. For test I, preliminary, 3 ball samples and 3 circular cones were made with pattern resin. For test II, 10 teeth shape rubber samples were used. Results and Conclusion : 1. The result of the accuracy test on 3D scan with 3 ball samples and 3 circular cones made of pattern resin has no significant difference(p<0.05). 2. The result of the accuracy test on 3D scan with 10 samples of tooth shape rubber has no significant difference (p<0.05). As a result, we may concluded the analysis of quantifying tooth wear used by 3D scan is useful in the clinic.