• Applied Chemistry for Engineering
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• v.7 no.5
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• pp.823-831
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• 1996

At the ratio [$H_2O$]/[TEOS]=1.7, the silica sol was synthesized by partial hydrolysis in the presence of acid catalyst. After stabilizing the silica sol by trimethylsilylation, the molecular weight and viscosity of the sol obtained at various reaction times were examined to determine a best spinnability of the sol. Gel fibers were prepared from the sol solution after removing solvent in the solution, and the gel fibers were heated at $1,000^{\circ}C$. The prepared silica fibers were in the shape of circular cross-section and their tensile strength and $SiO_2$ purity were $83{\pm}20kg/mm^2$ and about 99.997%, respectively.

• International Journal of Highway Engineering
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• v.5 no.4 s.18
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• pp.13-22
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• 2003

Several design methods from overseas are employed without considering different conditions such as material properties, climate, and traffic condition in this country. Therefore, there are limitations in application. Therefore, new pavement analysis system which is able to design a pavement efficiently and economically should be set up. In this study, 243 probable sections are classified depending on values of layer thickness and elastic modulus, and the effect of load types for the probable sections are analyzed. The section showing larger load distribution is chosen for analysis. As a result of sensitivity, a layer thickness has more influence on pavement than an elastic modulus does. The stress distribution of FWD test load is larger than that of circular load. This study compares outputs between nonlinear elastic model and linear elastic model. Based on the result, this study finds nonlinear elastic model considering stress condition in the ground is recommended for subbase.

• The Proceedings of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.5 no.2
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• pp.37-48
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• 1991

This paper shows the characteristics of sparkover discharge in flowing air ranging from O(Reynolds number, Re) to $10.52{\times}10^4$(Re). Also, we investigated changes of discharge pattern for constant input power by adjustment of the Reynolds number. Flowing air duct of this investigation is a circular tube. The flow at the experimented positions' section is described as fully development laminar flow. The important results obtained from this study are as follows. The sparkover discharge path of flowing air can be analyzed by the theories of flow field for air. The sparkover voltage shows nearly the maximum value when the Reynolds number of flowing air ranges $3{\times}10^4$ to $4{\times}10^4$The maximum sparkover voltages of flowing air are about 6.3[kV] higher than those of static air. The discharge pattern can be controlled by adjustment of the Reynolds number.

• Journal of the Korean Institute of Gas
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• v.17 no.1
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• pp.13-18
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• 2013

Experimental studies were carried out to investigate the interactions between the propagating flame fronts and different multiple obstacles within an explosion chamber. The explosion chamber is 600 mm in height, $700{\times}700mm^2$ in cross-section and has a H/L value of 0.86. Three different multiple obstacles with the blockage ratio of 0.43 were replaced within the chamber. The results showed that relatively higher local flame displacement speed was observed with the triangular obstacle while the lower was observed with the circular one. It was found that the local flame displacement speeds behind the obstacle were largely dependent on the obstacle types. It was also found that as the flame interacted with the flow field generated behind the obstacle, the probability density functions(PDFs) of the local flame displacement speed were extensively distributed toward higher speeds.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.38 no.10
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• pp.859-864
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• 2014

This experimental study investigates the effects of a downstream cylinder in the wake change on upstream object's diameter. A V-shaped object is placed in the upstream of the test section and a circular cylinder containing a load-cell is placed in the downstream. The velocity distribution of the wake generated from the upstream object with a change in its diameter is investigated. Further, the fluctuation in the lift coefficient and Karman-vortex emission frequency with a change in the position of the downstream cylinder is examined. The study results reveal the following. i) The flow velocity in the wake is smaller than that in the main stream. ii) The lock-in phenomenon occurs when the diameter of the upstream object is larger than that of the downstream cylinder. iii) To generate maximum fluctuating lift force of the downstream cylinder in the wake, the position of the downstream cylinder must be moved with changing diameter of the upstream object together.

• Steel and Composite Structures
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• v.28 no.5
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• pp.641-653
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• 2018

This paper presents experiment and bearing capacity analyses of steel dual-lintel column (SDC) joints in Chinese traditional style buildings. Two SDC interior joints and two SDC exterior joints, which consisted of dual box-section lintels, circular column and square column, were designed and tested under low cyclic loading. The force transferring mechanisms at the panel zone of SDC joints were proposed. And also, the load-strain curves at the panel zone, failure modes, hysteretic loops and skeleton curves of the joints were analyzed. It is shown that the typical failure modes of the joints are shear buckling at bottom panel zone, bending failure at middle panel zone, welds fracturing at the panel zone, and tension failure of base metal in the heat-affected zone of the joints. The ultimate bearing capacity of SDC joints appears to decrease with the increment of axial compression ratio. However, the bearing capacities of exterior joints are lower than those of interior joints at the same axial compression ratio. In order to predict the formulas of the bending capacity at the middle panel zone and the shear capacity at the bottom panel zone, the calculation model and the stress state of the element at the panel zone of SDC joints were studied. As the calculated values showed good agreements with the test results, the proposed formulas can be reliably applied to the analysis and design of SDC joints in Chinese traditional style buildings.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.20 no.2
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• pp.114-118
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• 1987

The authors carried out a model experiment to examine the hydrodynamic charactristics of the simple camber and the super-V otter board. The model otter boards are made of 1 mm thick iron plate. The simple camber otter board is made to have $12\%$ camber ratio and $432\;cm^2$ plane projected area, and the super-V otter board to have the same camber ratio as the former in every latitudinal section and almost the same plane projected area. The experiment had been done in a circular flow tank in the speed range of $0.1\~1.2m/sec$. As a result, it is examined that in the simple camber otter board the most effective angle of attack is about $25^{\circ}$, the shearing coefficient 1.47 and the drag coefficient 0.42, while in the super-V otter board they are about $20^{\circ}$, 1.40 and 0.40 respectively, so that the simple camber otter board performs a little better efficiency than the super-V otter board.

• Steel and Composite Structures
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• v.18 no.6
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• pp.1569-1582
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• 2015

This study explores the lateral deflections of diagonal braces in concentrically-braced earthquake-resisting frames. The performance of this widely-used system is often compromised by the flexural buckling of slender braces in compression. In addition to reducing the compressive resistance, buckling may also cause these members to undergo sizeable lateral deflections which could damage surrounding structural components. Different approaches have been used in the past to predict the mid-length lateral deflections of cyclically loaded steel braces based on their theoretical deformed geometry or by using experimental data. Expressions have been proposed relating the mid-length lateral deflection to the axial displacement ductility of the member. Recent experiments were conducted on hollow and concrete-filled circular hollow section (CHS) braces of different lengths under cyclic loading. Very slender, concrete-filled tubular braces exhibited a highly ductile response, undergoing large axial displacements prior to failure. The presence of concrete infill did not influence the magnitude of lateral deflection in relation to the axial displacement, but did increase the number of cycles endured and the maximum axial displacement achieved. The corresponding lateral deflections exceeded the deflections observed in the majority of the previous experiments that were considered. Consequently, predictive expressions from previous research did not accurately predict the mid-height lateral deflections of these CHS members. Mid-length lateral deflections were found to be influenced by the member non-dimensional slenderness (${\bar{\lambda}}$) and hence a new expression was proposed for the lateral deflection in terms of member slenderness and axial displacement ductility.

• Journal of architectural history
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• v.22 no.6
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• pp.7-22
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• 2013

The purpose of this paper is to study on the spatial characteristics from the "The Holy Trinity" fresco painted by Masaccio in the early Renaissance paintings. The results of this study are as follows. 1. The elevation composition of the "The Holy Trinity" fresco is divided into the upper and lower structure through horizontal axis on horizontal line around vanishing point. The upper structure is composed of vertical axis formed through the disposition of the "Trinity" elements and horizontal axis on horizontal line. The lower structure is composed of the sarcophagus and skeleton in such inside and the altar supported through circular columns of left and right. 2. The section composition of the "The Holy Trinity" fresco is composed of the ceiling structure of cylindrical-shaped vault on upper part around basic square floor plan that is interior space and upper structure. The exterior space and lower structure is placed with sarcophagus in inner part that altar and step is projected as same height and width in the outside direction. 3. The basic floor composition of the "The Holy Trinity" fresco is planned by square shape around structural columns that is placed at corners as symmetry through transverse, longitudinal and diagonal axis. The whole floor composition planned through the altar and step that is in exterior space at front, the apse of round form at rear part and the structure of the middle story concept at interior. 4. The visual aspect of the "The Holy Trinity" fresco is composed of the stable balance in relation with distance and height because the interior and exterior space as well as the upper structure and lower structure is formed by regular proportion system. The elevation angle of visual range was planned to view in detail generally or partially the architectural composition system and element, characters through proper visual distance, center and position.

• Journal of the Korean Association of Geographic Information Studies
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• v.11 no.3
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• pp.68-79
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• 2008

Ground vehicle borne system which is named RoSSAV(Road Safety Survey and Analysis Vehicle) developed in KICT(Korea Institute of Construction Technology) can collect road geometric data. This system therefore is able to evaluate the road safety and analyze road deficient sections using data collected along the roads. The purpose of this study is to extract road geometric data for 3D road modeling in dangerous road section and The system should be able to quickly provide more accurate data. Various sensors(circular laser scanner, GPS, INS, CCD camera and DMI) are installed in moving object and collect road environment data. Finally, We extract 3d road geometry(center, boundary), road facility and slope using integrated multi-sensor data.