• Journal of the Korea institute for structural maintenance and inspection
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• v.15 no.5
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• pp.124-135
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• 2011

The capacity of bearings installed at abutments and piers for continuous bridges is usually determined by the magnitude of the maximum vertical reaction at each support and the capacity of bearings placed at piers is higher than that at abutments. In this study, the possibility of the improved seismic performance of base-isolated continuous skew bridges was investigated by analysing the variation of the seismic behavior of them according to three arrangements of bearings. Based on the conventional arrangement of bearings(Case A), three arrangements of bearings such as Case A, Case B and Case C were selected considering the variation of the horizontal stiffness of the lead rubber bearing(LRB) installed at the pier. The seismic behavior of the total 36 skew bridges was investigated by conducting the response spectrum analysis using the hybrid response spectrum considered the effect of LRB's damping. Results of analyses show that a more desirable seismic behavior of base-isolated continuous skew bridges can be obtained by reducing the magnitude of the horizontal stiffness of LRB placed at the pier to similar to or less than that of LRB installed at abutments. The variation of LRB's stiffness at the pier brings about period elongation and the change of mode shapes of base-isolated skew bridges and results in the reduction of the total base shear, the maximum base shear at the pier and the girder stresses. Although positive effects on the seismic behavior of base-isolated skew bridges caused by the change of arrangement of bearings decreased slighty with an increase in the flexibility of the substructure, the proposed arrangements of bearings bring about the improved seismic performance of base-isolated continuous skew plate girder bridges with less than 10m height of piers.

• Journal of Adhesion and Interface
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• v.2 no.1
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• pp.9-17
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• 2001

Curing behavior and interfacial properties were evaluated using electrical resistance measurement and tensile/compressive fragmentation test. Electrical resistivity difference (${\Delta}R$) during curing process was not observed in a bare carbon fiber. On the other hand, ${\Delta}R$ appeared due to the matrix contraction in single-carbon fiber/epoxy composite. Logarithmic electrical resistivity of the untreated single-carbon fiber composite increased suddenly to the infinity when the fiber fracture occurred under tensile loading, whereas that of the ED composite reached relatively broadly up to the infinity. Comparing to the untreated case, interfacial shear strength (IFSS) of the ED treated composite increased significantly in both tensile fragmentation and compressive Broutman test. Microfailure modes of the untreated and the ED treated fiber composite showed the debonding and the cone shapes in tensile test, respectively. For compressive test, fractures of diagonal slippage were observed in both untreated and the ED treated composite. Sharp-end shape fractures exhibited in the untreated composite, whereas relatively dull fractures showed in the ED Heated composite. It is proved that ED treatments affected differently on the interfacial adhesion and microfailure mechanism under tensile/compressive tests.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.17 no.2
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• pp.119-129
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• 2004

A three dimensional (3D) method of analysis is presented for determining the free vibration frequencies and mode shapes of thick, circular and annular plates with nonlinear thickness variation along the radial direction. Unlike conventional plate theories, which are mathematically two dimensional (2D), the present method is based upon the 3D dynamic equations of elasticity. Displacement components u/sub s/, u/sub z/, and u/sub θ/ in the radial, thickness, and circumferential directions, respectively, are taken to be sinusoidal in time, periodic in θ, and algebraic polynomials in the s and z directions. Potential (strain) and kinetic energies of the plates are formulated, and the Ritz method is used to solve the eigenvalue problem thus yielding upper bound values of the frequencies by minimizing the frequencies. As the degree of the polynomials is increased, frequencies converge to the exact values. Convergence to four digit exactitude is demonstrated for the first five frequencies of the plates. Numerical results we presented for completely free, annular and circular plates with uniform linear, and quadratic variations in thickness. Comparisons are also made between results obtained from the present 3D and previously published thin plate (2D) data.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.31 no.5
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• pp.227-234
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• 2018

Researches regarding measurement and control of the dynamic behavior of liquid such as sloshing have been actively on undertaken in various engineering fields. Liquid vibration is being measured in the study of tuned liquid dampers(TLDs), which attenuates wind motion of buildings even in building structures. To overcome the limitations of existing wave height measurement sensors, a method of measuring liquid vibration in a TLD using a laser Doppler vibrometer(LDV) and galvanometer scanner is proposed in this paper: the principle of measuring speed and displacement is discussed; a system of multi-point measurement with a single point of LDV according to the operating principles of the galvanometer scanner is established. 4-point liquid vibration on the TLD is measured, and the time domain data of each point is compared with the conventional video sensing data. It was confirmed that the waveform is transformed into the traveling wave and the standing wave. In addition, the data with measurement delay are cross-correlated to perform singular value decomposition. The natural frequencies and mode shapes are compared using theoretical and video sensing results.

• Journal of the military operations research society of Korea
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• v.35 no.2
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• pp.33-49
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• 2009

The objective of this study is as follows. First, the hazard function on the failure probability density function of the K-1 tracked vehicles can be occurred in the form of the bathtub curve. Second, the failure mode may be different under two different operational situations. The research result shows that the bathtub curve can be fitted in the Weibull distribution, that assumes different shapes according to the specific stage of the system's life cycle. The K-1 tracked vehicle has a relatively high hazard(failure) rate at the time of its first service. The failure rate starts decreasing for a time immediately after it goes into service. After the break-in period, the surviving components have a fairly constant hazard rate. As the K-1 system ages, deterioration of its various parts takes place and the hazard rate starts Increasing. Second, the result shows the failure rate in the harsh operational environment is higher than that in the mild operational environment. In conclusion, the bathtub curve can be logically appropriate in establishing the depot overhaul cycle. Moreover, it is necessary for determining the right time of the depot overhaul to consider not only the age of defense equipment but also the different operational environment.

• Economic and Environmental Geology
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• v.35 no.3
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• pp.191-201
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• 2002

The Gubong gold-silver deposits if gold-silver-bearing hydrothermal massive quartz veins which were filled the fractures along fault shear (NE, NW) zones within Precambrian banded or granitic gneiss of Gyeonggi massif. Ore mineralization of this deposits is contained within a single stage of quartz vein which was formed by multiple episodes of fracturing and healing. Ore minerals are comported mainly of arsenopyrite, pyrite, sphalerite, chalcopyrite, galena with minor amounts of pyrrhotite, marcasite and electrum. The frequency and volume percentages of electrum associated with ore minerals from this deposits are recognized as follows; 44.5% and 54.3% with arsenopyrite, 24.3% and 33.8% with quartz, 12.6% and 0.1% with pyrite, 11.0% and 4.8% with galena, 5.0% and 7.0% with sphalerite and 2.5% and 0.02% with chalcopyrite, respectively. They show irregular (41.6%), subround (34.7%), elongate (17.0%) and granular (6.6%) shapes, respectively. Their grain size ranges from 2 to 150 um, but 90.9 percent of the grains are below 30 um. The chemical composition of electrums ranges from 26.39 to 72.51 Au atomic %. These composition (Au atomic %) on the basis of associated minerals are from 44.97 to 71.75 with arsenopyrite, pyrite, sphalerite and quartz, from 44.37 to 72.51 with quartz, from 35.40 to 41.01 with sphalerite and chalcopyrite, from 26.39 to 54.84 with pyrite, chalcopyrite, quartz and galena, from 28.49 to 53.28 with galena, respectively. We suggest that optimum recovery of gold would be obtained with reference to these results.

• Journal of the Korean Institute of Gas
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• v.25 no.6
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• pp.53-65
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• 2021

While the hydrogen refueling station is rapidly expanded and installed, the safety inspection of the hydrogen pressure vessel in the station should be very important. Of these, according to ASME, hydrogen embrittlement tests must be performed for hydrogen vessel that store hydrogen above a certain pressure. The main test method for hydrogen embrittlement inspection is to carry out fracture tests and fatigue fracture tests in a high pressure hydrogen atmosphere, which allows the durability limit of the pressure vessel to be measured and the endurable limit to be determined in the hydrogen atmosphere. In detail, the critical crack depth can be calculated by the stress intensity factor(K), and the service life can be determined by da/dN (fatigue growth rate). API579-1/ ASME FFS-1 part 9 exemplifies the calculation method according to the mode of crack-like flaws, but for various shapes such as plates and cylinders, there are about 55 modes according to the shape and location of the crack. Due to the fairly complex formula, it is not easily accessible. In this study, we will show you how to calculate fracture mechanics numerically via Excel and VBA. In addition, this was applied to analyze the effects of the thickness and inner diameter of the pressure vessel on the service life.

• Journal of Science of Art and Design
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• v.3
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• pp.145-177
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• 2001

The artist's interest has been captivated by ecological phenomena in Nature. Her keen captivation has then been focused into plastic art depicting the image of primitive life. The wide sweep of her work encompasses the totality of nature which consists of the human's subconscious power and imagination which she then portrays by organic images. These organic images are in contrast to scientific, mathematical and logical inference and consciousness. This research examines the character of the organic images in modern art by her analysis of some representative works by others. The image is an essential concept in the art which appeared in very different ways and in different perspectives. The image in the artwork appears to be the realistic expression until the early part of the 20th Century. Well into the 20th Century, it began being expressed in various ways such as combined images by imagination which is combined or rejected in the story of artwork. It also began being expressed by transferred images by changed original conditions. It is the main purpose of this research is to study of various expressions of organic images in the artwork of the Post-Modernism era. The character and meaning of organic image painting helps people to approach the human instinct more easily to find out the natural essence. It is also an objective of the organic image to tenderise our human sensibilities, thus helping us to regain vitality and recover our poor humanity in the barren wilderness of modern society. 'Life communion with nature' is a meeting point and common ground for Oriental Philosophy and organic image painting. Through this research, organic image painting is characterised in the four following ways : 1st) Organic image painting seeks regularity and perfection of outer shapes, in contrast to disordered and deformed nature, resulting in organic and biotic formalistic mode of plastic art. 2nd) Organic image painting seeks the formative. 3rd) Organic image painting pursues the priceless dignity of life by researching the formatted arrangement and figure, which contains primitive power of life. 4th) Organic image painting makes crystal clear the power of human and nature, which is a historic and biological phenomenon. This, in turn, exposes the humanistic view of the world from modern society best characterised in lost self-understanding, isolation and materialism. The representative organic image painting artists are Elizabeth Murray, Kusama Yayoi, and Niki do Saint Phalle. Elizabeth Murray used shaped canvas and a round construction of relief works. Kusama Yayoi used Automatistic expressionism originating from the realms of unconsciousness and which is represented by the mass and shape of a water drop. Niki do Saint Phalle shows the transcendence of universal life and anti-life to respect the dignity of life and the eco-friendliness relationship of human and nature in the post-modernism in art history. This is accomplished by surrealistic, symbolic, fantastic and humoristic expression. These three artists' works express the spirit of the organic image in contemporary art. It contains the stream of nature and life to seek not only the state of materialism in the reality, but also the harmonized world of nature and human which has almost lost the important meaning in modern times. Finally, this organic image is the plastic language of the majestic life. It is the romantic idea that the intimacy of nature and the universe and Surrealism, which emphasizes the unconsciousness , is the source of truth and spirit. Also it is influenced by primitive art and abstract art. According to this research, the subject 'Research About Organic Images' is not only an important element in the plastic arts from primitive society to the present, but is also fundamental to an true understanding of Post-Modernism.

• Journal of the Korea Concrete Institute
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• v.22 no.6
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• pp.851-858
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• 2010

In this study, waste glass and bottom ash were used as basic materials in order to secure a recycling technology of by-products which was mostly discarded and reclaimed. In addition, because softening point of waste glass is less than $700^{\circ}C$ and bottom ash includes combustible material, it was possible to manufacture low-temperature sintering lightweight aggregates for energy saving at $800{\sim}900^{\circ}C$ that it is as much as 20~30% lower than sintering temperature of existing lightweight aggregates. Thermal conductivity of newly-developed lightweight aggregates was 0.056~0.105W/m. K and its porosity was 40.36~84.89%. A coefficient of correlation between thermal conductivity and porosity was -0.97, it showed very high negative correlationship. With this, we were able to verify that porosity is key factor to affect thermal conductivity. Microstructure of lightweight aggregates by $CaCO_3$ content and replacement ratio of bottom ash in the variation of temperature were that $CaCO_3$ content increased along with pore size while replacement ratio of bottom ash increased as pore size decreased. Specially, most pores were open pore instead of closed pore of globular shape when replacement ratio of bottom ash was 30%, and pore size was small about 1/10~1/5 as compared with case in bottom ash 0~20%. In addition, open pore shapes were remarkably more irregular form of open pore in $900^{\circ}C$ than $700^{\circ}C$ or $800^{\circ}C$ when replacement ratio of bottom ash was 30%. We reasoned hereby that these results will influence on absorption increase, strength and thermal conductivity decrease of lightweight aggregates.

• Journal of Dental Rehabilitation and Applied Science
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• v.25 no.3
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• pp.211-224
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• 2009

The objective of this study is to examine the condylar surfaces in order to find out the types, the incidence and common occurrence area of the osseous abnormalities of the condyles according to the age, genders and the purpose of CT taking, and to compare those between the groups for TMD diagnosis and the other groups. 3D CT images of 199 patients which were scanned with the $i-CAT^{TM}$ Cone Beam Computed Tomography were collected from Sanbon Dental Hospital of Wonkwang university and the MPR images were transfered to the TMJ mode to be showed serial sagittal images and coronal images. The images were macroscopically examined by three independent observers for the types and incidences of the osseous abnormalities, their common occurrence area and general shapes of the condyles. As a result, type F is most common ever than type N. The common occurrence area in sagittal images is antero-superior and superior area except for type D-C which were showed on postero-superior area commonly. In coronal images, latero-superior and superior area is most common except for type E which were present on mesio-superior and superior area most frequently. The osseous abnormalities of the condyles are more common in TMD diagnosis group except for type D-C, that is type N and type D-C are more common in the other groups. In this study, abnormalities of the condyles are classified into 6 types and it has a common occurrence area each. And TMD diagnosis group shows a tendency to have higher rate for osseous abnormalities except for type D-C.