• Proceedings of the Korean Vacuum Society Conference
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• 1999.07a
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• pp.169-169
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• 1999

We studied magnetic properties of co thin films deposited on Pd (111) surface, which attracted much attention recently due to the perpendicular magnetic anisotropy, using magnetic circular dichroism(MCD). Special attention was paid on the effect of Pd capping and interface roughness on the direction of magnetic easy axis, and for that purpose MCD signals for all Co thicknesses were measured with two different ways : in-plane and out-of-plane geometry. In case of bare Co films deposited on smooth Pd(111) surface, no MCD signal was observed under 4$\AA$ co thickness. At 4$\AA$ Co thickness, MCD signal at the out-of-plane geometry was observed, and for thicker Co films, only in-plane MCD signal was measured. This type of magnetic easy axis transition has been reported for other cases like Co/Pt system. The effect of 5$\AA$ Pd capping on these bare Co films made an remarkable change on the transition of magnetic easy axis. Out-of-plane MCD signals exists up to 20$\AA$ Co thickness, and disappears at 24$\AA$ Co thickness. In-plane MCD signals first appears at 10$\AA$ Co thickness and gradually increases up to 24$\AA$ Co thickness. Between 10$\AA$ and 20$\AA$ Co thickness, in-plane and out-of-plane MCD signal coexist. The formation of multi-domain structure or the existence of tilted magnetic easy axis is an possible scenario for such an interesting coexistence. The effect of interface roughness was also tested by measuring MCD signal on Co films deposited on un-annealed Pd(111) surface. Out-of-plane MCD signal was observed up to 8$\AA$ Co thickness and the anisotropy of MCD signal at 4$\AA$ Co thickness was very large with respect to that of Co film deposited on the smooth substrate. Above 8$\AA$ thickness, there exists only in-plane MCD signal. From above results, it was concluded that both Pd capping and interface roughness induce and reenforce the perpendicular magnetic anisotropy. The large perpendicular magnetic anisotropy of Co/Pd multilayer system made by sputtering method can be well understood from our results.

• Journal of the Korea Concrete Institute
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• v.15 no.2
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• pp.288-296
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• 2003

Generally, application of steel pipe pile as deep foundation member needs special requirement for the connection method between steel pipe pile and concrete footing. Even though two types of connection method are suggested in the related specification, type B-method is provident. To investigate real structural behavior of type B connection, several load tests are done with carefully designed experimental system. The purpose of this experiment is mainly focused on the understanding of actual behavior which can be predicted by design theory. At this research stage, vertical and lateral loading test are done for three types of specimen to review stress concentration, formation and behavior of imaginary RC column in the footing and effect of non-slip device installed in the steel pipe pile. The load resistance mechanism in these specific connection method is predicted based on both experimental results. The three-dimensional finite element modeling is also done for the purpose of comparison between numerical and experimental result. With all the results gained from experiment the structural behavior of imaginary RC column in the design concept is confirmed. The role of non-slip device is very important and it affects the resistance capacity with help of composite action of concrete and steel pipe pile.

• Geomechanics and Engineering
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• v.20 no.6
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• pp.537-546
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• 2020

Oil and natural gas reserves have been recognised abundantly in clayey rich rock formations in deep costal reservoirs. It is necessary to understand the sedimentary history of those reservoir rocks to well explore these natural resources. This work designs a group of laboratory experiments to mimic the physical process of the sedimentary clay-rich rock formation. It presents characterisation results of the physical properties of the artificial clayey rocks synthesized from illite clay, quartz sand and brine water by high-pressure consolidation tests. Special focus is given on the effects of illite clay content and high-stress consolidation on the physical properties. Multi-step loaded consolidation experiments were carried out with stress up to 35 MPa on mixtures constituting of the illite clay, quartz sand and brine water with five initial illite clay contents (w=85%, 70%, 55%, 40% and 25%). Compressibility and void ratio were characterised throughout the physical compaction process of the mixtures constituting of five illite clay contents and their water permeability was measured as well. Results show that the applied stress induces a great reduction of clayey rock void ratio. Illite clay contents has a significant influence on the compressibility, void ratio and the permeability of the physically synthesized clayey rocks. There is a critical illite clay content w=70% that induces the minimum void ratio in the physically synthesised clayey rocks. The SEM study indicates, in the high-pressure synthesised clayey rocks with high illite clay contents, the illite clay minerals are located in layers and serve as the material matrix, and the quartz minerals fill in the inter-mineral pores or are embedded in the illite clay matrix. The arrangements of the minerals in microscale originate the structural anisotropy of the high-pressure synthesised clayey rock. The test findings can give an intuitive physical understanding of the deep-buried clayey rock basins in energy reservoirs.

• Journal of the Korean Institute of Landscape Architecture
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• v.36 no.1
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• pp.80-89
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• 2008

Generally, trees lining the streets are the most easily accessible green areas in the city and constitute the smallest basic unit in the formation of the urban linear green axis. This study attempts to interpret issues related to city trees from a comprehensive and relational viewpoint. The site of this study is Central Park Street in front of Incheon Metropolitan City Hall. This street is representative of those in Incheon City. This study is an inter-relational interpretation of issues by measuring the vitality of these trees. The following are results of this study: First, the vitality of city trees is higher in those trees growing in natural ground than those growing in plant gratings. This observation can lead to budget savings and increased natural areas in the city. Also, if planter and multi-layering planting methods are introduced where damage to trees is predicted, variation to urban landscape can be achieved while linking to reinforced rearing foundation of street-side trees. Second, there is need for a holistic approach to caring for street-side trees regarding the damage caused by drastic pruning and strong street lights. The typical functions of these trees, like supplying freshness in summer, absorbing solar radiation, and controlling the urban micro-climate are closely related to the vitality of the trees. Accordingly, the function and ecology should be understood holistically, not separately. In this aspect, the functional and ecological use of the multi-layering planting method is effective in protecting pedestrians from vehicles as well. Third, the fallen leaves of monotonous rows of trees have different ecological and functional effects. Not only is the index of greenness in the urban setting increased, but there are also aesthetic and symbolic effects. Fourth, in spite of being the street along which Incheon Metropolitan City Hall, major administrative buildings and Central Park are located, this street does not have its own special identity to discriminate it from other streets. It fulfills only functional criteria based on uniformity. If there is no paradigm shift from today's street system based on vehicles, the role of landscape architecture will be very passive in regards to street-side trees, the minimum unit of urban green. Fifth, on this particular street, many trees were planted in December, which reflects a deficiency of short and long-term strategy, like a street-tree master plan. In this aspect, we still lack a mature culture concerning these trees as a basic unit in urban greenery. Furthermore, there needs to be cultural introspection concerning present administrative practices.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.12
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• pp.644-649
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• 2017

In the automobile industry, there is growing demand for lightweight vehicles due to environmental problems and rising oil prices. Therefore, aluminum alloys and special materials are being used to reduce the weight of vehicles, but there are still many difficulties to overcome in terms of cost and strength. Therefore, the application of advanced high strength steel (AHSS)is increasing. AHSS has good strength and formability.Safety regulations are becoming stricter, and 1.2-GPa super-high-strength steels are gradually being applied for the center pillar and roof rails. Thus, the application of different kinds of steels in automobile bodiesis also increasing gradually. This study evaluates the resistance point weldability and the characteristics of a welded part of SGAFC1180 1.2t steel. A simulation was used to observe the nugget formation and its growth behavior. The prediction performance showed a similar tendency within an error rate of 10%. Also, the effect of this behavior on the process resistance and dynamic resistance was investigated,along with the correlation between the shear tensile strength and nugget diameter.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2013.04a
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• pp.842-848
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• 2013

Developments of Solid-State Gyroscopy during last decades are impressive and were based on thin-walled shell resonators like HRG or CRG made from fused quartz or leuko-sapphire. However, a number of design choices for inertial-grade gyroscopes, which can be used for high-g applications and for mass- or middle-scale production, is still very limited. So, considerations of fundamental physical effects in solids that can be used for development of a miniature, completely solid-state, and lower-cost sensor look urgent. There is a variety of different types of bulk acoustic (elastic) waves (BAW) in anisotropic solids. Shear waves with different variants of their polarization have to be studied especially carefully, because shear sounds in glasses and crystals are sensitive to a turn of the solid as a whole, and, so, they can be used for development of gyroscopic sensors. For an isotropic medium (for a glass or a fine polycrystalline body), classic Lame's theorem (so-called, a general solution of Elasticity Theory or Green-Lame's representation) has been modified for enough general case: an elastic medium rotated about an arbitrary set of axes. Travelling, standing, and mixed shear waves propagating in an infinite isotopic medium (or between a pair of parallel reflecting surfaces) have been considered too. An analogy with classic Foucault's pendulum has been underlined for the effect of a turn of a polarizational plane (i.e., an integration effect for an input angular rate) due to a medium's turn about the axis of the wave propagation. These cases demonstrate a whole-angle regime of gyroscopic operation. Single-crystals are anisotropic media, and, therefore, to reflect influence of the crystal's rotation, classic Christoffel-Green's tensors have been modified. Cases of acoustic axes corresponding to equal velocities for a pair of the pure-transverse (shear) waves have of an evident applied interest. For such a special direction in a crystal, different polarizations of waves are possible, and the gyroscopic effect of "polarizational precession" can be observed like for a glass. Naturally, formation of a wave pattern in a massive elastic body is much more complex due to reflections from its boundaries. Some of these complexities can be eliminated. However, a non-homogeneity has a fundamental nature for any amorphous medium due to its thermodynamically-unstable micro-structure, having fluctuations of the rapidly-frozen liquid. For single-crystalline structures, blockness (walls of dislocations) plays a similar role. Physical nature and kinematic particularities of several typical "drifts" in polarizational BAW gyros (P-BAW) have been considered briefly too. They include irregular precessions ("polarizational beats") due to: non-homogeneity of mass density and elastic moduli, dissymmetry of intrinsic losses, and an angular mismatch between propagation and acoustic axes.

• Journal of the Korean Society of Clothing and Textiles
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• v.11 no.2 s.24
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• pp.37-55
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• 1987

Pasul (Herein after referred to Korean-styled Pasul) to cover up the secrets, which has originated from Bool-an original mode of clothes is to put around a belt with a kind of towel. With the development of culture, it has been handed down the parts of ornamental and symbolic functions, losted its particular and original one. In general, we cannot exactly show when the Pasul has been used as a ritual dress, but, dare to maintain in this thesis, which has been used in Koguryu era. This thesis is summarized as follows: 1. The Bool, which is the first dress of all has its origin in the prehistory, and gradually has developed to a ceremonial dress with the help of man's intelligence. 2. Korean-styled Pasul has continuously been handed down from generation to generation (to adding up, from Koguryu era to Yi dynasty). Today, the color of the Pasul is known as a pink one, but I, herein, would like to refer that king Kojong in Yi dynasty had on a yellow-colored Pasul. 3. With becoming to be a form of ceremonial dress, the Bool has become to be complicated in style. For example, in the Koguryu era, the style is in the form of 'U,' and in Koryu era, it is the echelon formation tinting a pink color and weaving a mountain and flare shaped designs, and its dimension, the upper is one ja (a ja means a unit of length, 0.33 M), the lower, two ja, its length three ja. The Bool of Yi dynasty tints a pink color, and weaves a seaweeds, rices, axes and shaped designs. The Pasul which King Kojong in Yi dynasty put in, was a yellow-colored one weaving dragons and fire shaped design. 4. The Pasul is a ceremonial dress used a ritual or court dress. The purposes of wearing it are to distinguish the upper from the lower classes, to make them abide by regulations, and to respect courtesy. Accordingly, the Pasul. as the dress for special occassions does make us review the old and learn the new. 5. The reason that Pasul has been handed down are: 1) richness and fecundity. 2) symbol mark to represent classicalism. 3) to symbolize the authority by putting on it, for it is necessary to distinguish the upper from the lower classes along with the class consciousness in society. 6. On the basis of the study, the Pasul transition is to be handed down the function of the ornament and symbol. after losted its original functions, with the development of culture.

• Applied Microscopy
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• v.22 no.2
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• pp.84-96
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• 1992

This study was carried out to examine the $H^+$ transport mechanism by observing the properties of cellular membrane having an ${\alpha}$ type of carbonic anhydrase (CA)-containing cells in turtle urinary bladder. The urinary bladder consists of a heterogenous population of cells. As a result of fine observation with traditional thin-section electron microscopy. the bladder epithelium has three different cell types on mucosal surface. They are a basal cell, a granular cell and a third type of CA-rich cell. The CA-rich cells are divided into two distinct smaller groups within them and called them ${\alpha}$ type and ${\beta}$ type of CA cells. The ${\alpha}$ type of CA cells are responsible for the proton secretion using the proton pumps on the apical plasma membrane, while the ${\beta}$ type of CA cells secrete bicarbonate via an oppositely-directed proton pumps in their basolateral plasma membrane. After performing the freeze-fracture technique, it was shown that there were distributed a large number of intramembranous particles having a special structure on the apical membrane of ${\alpha}$ type of CA-rich cells in the process of their $H^+$ secretion. In turtle bladder ${\alpha}$ type of CA-rich cells, this particle was the only prominent structure in the apical membrane. These intramembrane rod-shaped particles probably represent the integral membrane components of the proton pump. This result may explain that carbonic anhydrase within epithelial cell of urinary bladder takes part in formation of $H^+$ and bicarbonate, that active transport of $H^+$ is done, and that the reabsorption of bicarbonate suggests transport mechanism containing $H^+$ secretion. However, it seems that more studies are required for considering their regular transport pathway.

• Applied Chemistry for Engineering
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• v.16 no.4
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• pp.474-484
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• 2005

Biological treatment is a promising alternative to conventional air pollution control methods. Bioreactors for air pollution control have found most of their success in the treatment of dilute and high flow waste air streams containing volatile organic compounds and odor compounds. They offer several advantages over traditional technologies such as incineration or adsorption. These include lower treatment costs, absence of formation of secondary pollutants, no spent chemicals, low energy demand and low temperature treatment. The most widely used bioreactor for air pollution control is biofilter, but it has several limitations. In the past years major progress has been accomplished in the development of vapor phase bioreactor, in particular biotrickling filters. Biotrickling filters are more complex than biofilters, but are usually more effective, especially for the treatment of compounds which are difficult to degrade or compounds that generate acidic by-products. While the level of understanding of biotrickling filtration process for VOCs still remains limited, the evident success of biotreatment of VOC in air stimulated the pursue of acitve research. This paper presents fundamental and theoretical/practical aspect of air pollution control in biotrickling filter. Special emphasis is given to the operating parameters and the factors influencing performance for air pollution control in biotrickling filter.

• Clean Technology
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• v.13 no.1 s.36
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• pp.1-15
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• 2007

Biological treatment is a relatively recent air pollution control technology in which off-gases containing biodegradable odors and volatile organic compounds(VOCs) are vented through microbes. It is a promising alternative to conventional air pollution control methods. Bioreactors for air pollution control have found most of their success in the treatment of dilute and high flow waste air streams containing VOCs and odor compounds. They offer several advantages over traditional technologies such as incineration or adsorption. These include lower treatment costs, absence of formation of secondary pollutants, no spent chemicals, low energy demand and low temperature treatment. The three most widely used technologies are described, namely biofiltration, biotrickling filtration, bioscrubbing. The most widely used bioreactor for air pollution control is biofilter, but it has several limitations. In the past years major progress has been accomplished in the development of vapor phase bioreaction systems, for solving problems of biofilter. Biotrickling filters are more complex than biofilters, but are usually more effective, especially for the treatment of compounds which are difficult to degrade or compounds that generate acidic by-products. This, paper reviews fundamental and theoretical/practical aspect of air pollution control in biofilter, biotrickling filter and bioscrubber, focusing more extensively on biotrickling filtration. Special emphasis is given to the operating parameters and the factors influencing performance for air pollution control, and cost estimation in biotreatment technologies.