• Journal of Korean Society of Forest Science
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• v.76 no.3
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• pp.206-217
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• 1987

To investigate and analyze the vegetational structure, thirty sites were sampled with clumped sampling method and seventeen belt transects were sampled to analyze the vegetational change during 8 years(from 1978 to 1986)at the Namsan Nature Park in Seoul. Robinia pseudoacacia community of actual vegetation covered 29.39%, Quercus mongolica community 21.25% and Pinus densiflora community 17.58% of the Mt. Namsan forest. The degree of human disturbance of vegetation of 8, 7 and 6 area covered 43.2%, 7.8% and 30.8% respectively. The Quercus mongolica community at the northern slope and R. pseudoacacia community at the edge zone will keep their present structure. And P. densiflora community at the eastern and southern slope shall be succeeded to deciduous trees such as Q. mongolica. As to changes of plant community structure during 8 years, density of understory species, species diversity and Raunkiaer's frequency class A and E showed an increase and vegetation structure was developed to unification.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.27 no.4
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• pp.244-249
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• 2014

In this research, it have developed a sensor that could diagnose inner deterioration of covered wires. With this sensor it observed results from simulation, and the attribute required for realization. For simulation it have used FLUX, it have considered all of geometric and electromagnetic information from coil and base metal that influences eddy current sensor's property in order to predict the final result. It assumed there is no mutual inductance in the coil with N number of turns, because equivalent current flows in coil that is continuously connected in eddy current sensor. It assumed circular coil loop draws a circle, always have self inductance, and they are connected in series and overlapped according number of turns (N) in coil, and bobbin configuration. Actual sensor was produced with consideration of inductance and number of turns (N). In conclusion, it were able to test the dependency through results from simulation, actual measurement, and modeling of simulation. It is considered that attributes of respective base metal and structure can be predicted by simulating in advance.

• Journal of the Korean Electrochemical Society
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• v.10 no.3
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• pp.179-183
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• 2007

The corrosion behavior of metal covered with mortar under a wet-dry cyclic condition were investigated to apply for the measurement of corrosion rates of reinforcing steel in concrete structure. The carbon steel in mortar having t=3 mm cover thickness was exposed to the alternate condition of 6 h immersion in chloride containing solution and 18 h drying at $25^{\circ}C$ and 50%RH. The electrochemical phenomena of a carbon steel and mortar interface was explained by an equivalent circuit consisting of a solution resistance, a charge transfer resistance and a CPE(Constant Phase Element). The corrosion rates were monitored continuously during exposure using an AC impedance technique. Simultaneously, the current distribution over the working electrode during impedance measurement was analyzed from the phase shift, $\theta$, in an intermediate frequency. The result showed that corrosion rate monitoring using an AC impedance method is suitable under the given exposure conditions even during the drying period when the metal is covered with the wetted mortar.

• Proceedings of the Korean Vacuum Society Conference
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• 2011.08a
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• pp.160-160
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• 2011

In the present work, $TiO_2$ fiilms supported by porous silica gel with high surface area synthesized by atomic layer deposition(ALD). Porous structure of silica substrate could be maintained even after deposit large amount of $TiO_2$ (500 cycles of ALD process), suggesting the differential growth mode of $TiO_2$ on top surface and inside the pore. All the $TiO_2$-covered silica samples showed improved MB adsorption abilities, comparing to bare one. In addition, when silica surface was covered with $TiO_2$ films, MB adsorption capacity was almost fully recovered by re-annealing process (500$^{\circ}C$, for 1 hr, in ambient pressure), whereas MB adsorption capacity of bare silica was decreased after re-heaing process. FT-IR study demonstrated that $TiO_2$ film could prevent deposition of surface-bound intermediate species during thermal decomposition of adsorbed MB molecules. Photocatalytic activity of $TiO_2$/silica sample was also investigated.

• Journal of Plant Biology
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• v.1 no.1
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• pp.17-24
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• 1958

The author investigated the plant sociological studies on the flora of Inchon districts coast area. (It contains also province of Buchun, Kumpo, and Hwasung, the island of Kanghwa.) The scenery of the west coast in Korea is very curious, because the soil in this area contains comapratively large amount of mud and small sand. Some parts of this area is covered with only mud, and the area between the line of high tije and line of low tide is very vast. When a low tide was appearel, there were vast moddel places appeared about 10 km in length. The author could distinguish $\varepsilon$ different types of communties in this zone. (1) Suaeda jatonica community (2) Statice japonica community (3) Scirtus triqueier community (4) Zoy_ia community (5) Phragmites community (6) Carex Pumilla community (7) Atriolex subsodata community (8) Rosa rugasa community (1), (2), (3), (4) communities can grow under the high tide. (When the high tide comes they soaked in the sea water.) (1) Suaeda community is the most popular type of the Yellow sea. It is very wonderful scene that the vast area (the length of 10 km) is covered with this Suaeda, and it looks like to be painted with blood. (2) Staice (3) Scirpus (4) Zoysia community is can fully maintain their glorious life in the sea water. It is due to the this plants tolerance of salt. (1), (2), (3), (4) communities are very strong to the tolerance of salt, especially the Suaeda is remarkable. The structure and some sucession I trend of each community were studied in detail and the mutual relations among the communites were also concluded.

• Structural Engineering and Mechanics
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• v.56 no.3
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• pp.491-506
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• 2015

Propagation of the generalized Rayleigh waves in an initially stressed elastic half-space covered by an elastic layer is investigated. It is assumed that the initial stresses are caused by the uniformly distributed normal compressional forces acting on the face surface of the covering layer. Two different cases where the compressional forces are "dead" and "follower" forces are considered. Three-dimensional linearized theory of elastic waves in initially stressed bodies in plane-strain state is employed and the elasticity relations of the materials of the constituents are described through the Murnaghan potential where the influence of the third order elastic constants is taken into consideration. The dispersion equation is derived and an algorithm is developed for numerical solution to this equation. Numerical results for the dispersion of the generalized Rayleigh waves on the influence of the initial stresses and on the influence of the character of the external compressional forces are presented and discussed. These investigations provide some theoretical foundations for study of the near-surface waves propagating in layered mechanical systems with a liquid upper layer, study of the structure of the soil of the bottom of the oceans or of the seas and study of the behavior of seismic surface waves propagating under the bottom of the oceans.

• Korean Journal of Food Science and Technology
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• v.18 no.3
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• pp.215-220
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• 1986

Mechanical properties of 9-30% starch gels from naked and covered barley were investigated with rheometer or rotation viscosimeter. The compression-penetration curves of 20 and 30% gels were characterized by deformations containing elastic, plastic and fracture regions under the load of 0-2kg. The compressive stress relaxation test showed that the viscoelastic properties of 20% gels may be represented by four element Maxwell model consisting of two Maxwell element in parallel. Also, stress-decay under the steady shear of 9% covered starch gel was able to be interpreted by linear viscoelastic model and stress-decay process was suggested to be effective to investigate the effect of temperature or additives on gel structure.

• Journal of Elementary Mathematics Education in Korea
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• v.24 no.3
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• pp.259-277
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• 2020

The purpose of this study was to develop and validate a scale of Korean elementary teachers' mathematics beliefs. We examined 299 elementary teachers' mathematical beliefs using 30 items, out of which 12 items covered beliefs about the nature of mathematics and 18 items covered beliefs about mathematics teaching and learning. In the first stage, we performed exploratory factor analysis using 149 survey data to examine the factor structure. In the second stage, we performed confirmatory factor analysis using 150 survey data. Building upon previous studies, we examined the construct validity of three different models to find the best factor structure. The study results indicate that the four-factor model with 14 items provides the best fit for the data: transmissive view of mathematics, constructivist view of mathematics, transmissive view of teaching and learning, and constructivist view of teaching and learning. The findings of the study reveal that each factor has adequate internal consistency and reliability. These results confirm that the beliefs scale is a reliable and valid measurement tool to measure Korean elementary teachers' mathematical beliefs. The implications of the study are discussed.

• Structural Engineering and Mechanics
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• v.75 no.4
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• pp.487-496
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• 2020

Most of the previous works on numerical analysis of galloping of transmission lines are generally based on the quasisteady theory. However, some wind tunnel tests of the rectangular section or hangers of suspension bridges have shown that the galloping phenomenon has a strong unsteady characteristic and the test results are quite different from the quasi-steady calculation results. Therefore, it is necessary to check the applicability of the quasi-static theory in galloping analysis of the ice-covered transmission line. Although some limited unsteady simulation researches have been conducted on the variation of parameters such as aerodynamic damping, aerodynamic coefficients with wind speed or wind attack angle, there is a need to investigate the numerical simulation of unsteady galloping of two-dimensional iced transmission line with comparison to wind tunnel test results. In this paper, it is proposed to conduct a two dimensional (2-D) unsteady numerical analysis of ice-covered transmission line galloping. First, wind tunnel tests of a typical crescent-shapes iced conductor are conducted firstly to check the subsequent quasisteady and unsteady numerical analysis results. Then, a numerical simulation model consistent with the aeroelastic model in the wind tunnel test is established. The weak coupling methodology is used to consider the fluid-structure interaction in investigating a two-dimension numerical simulation of unsteady galloping of the iced conductor. First, the flow field is simulated to obtain the pressure and velocity distribution of the flow field. The fluid action on the iced conduct at the coupling interface is treated as an external load to the conductor. Then, the movement of the conduct is analyzed separately. The software ANSYS FLUENT is employed and redeveloped to numerically analyze the model responses based on fluid-structure interaction theory. The numerical simulation results of unsteady galloping of the iced conduct are compared with the measured responses of wind tunnel tests and the numerical results by the conventional quasi-steady theory, respectively.

• Journal of Magnetics
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• v.3 no.2
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• pp.44-48
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• 1998

Scanning Electron Microscopy with Polarization Analysis (SEMPA) was used to image the surface magnetic domain structure of the 100 ${\mu}{\textrm}{m}$ thick 3% Si-Fe sheet. The thin-gauged 3% Si-Fe strips with magnetic induction ($B_{10}$) from 1.98 to 1.57 Tesla were prepared via conventional metallurgical processes including melting, hot-and cold-rolling, intermediate annealing and final annealing. Using SEMPA, it was observed that the $B_{10}$ (1.98 T) Tesla sample was almost composed of 180$^{\circ}$ stripe domains which are parallel to rolling direction. On the other hand the 3% Si-Fe sheet with $B_{10}$ (1.57 T) Tesla was composed of large 180$^{\circ}$stripe domains that are slanted about 30$^{\circ}$to the rolling direction and complex magnetic domain structures like tree and zigzag pattern. The 180$^{\circ}$stripe domains, which covered a major part of the sample, had (110)<001> Goss texture parallel to the rolling direction. The domain walls between 180$^{\circ}$stripe domains were the conventional Bloch type walls. On the other hand, the 90$^{\circ}$domains, which covered minor part on edge of the sample, were observed in (200) grains. The domain walls between 90$^{\circ}$domains were the Neel type walls. In high magnification, the elliptical singularity at the Neel walls was clearly observed.