• Transactions of the Korean Society of Mechanical Engineers B
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• v.25 no.1
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• pp.71-77
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• 2001

A flow visualization study using the oil film method and the smoke-laser light sheet arrangement is carried out to investigate the three-dimensional flow pattern around the free end surface region of a finite circular cylinder (aspect ratios of 1.25 and 4.25) mounted on a flat plate. The experiment is performed for the cases of two Reynolds numbers: 5.92${\times}$10$^3$and 1.48${\times}$10(sup)5. Various kinds of singular points on the free-end surface are disclosed from the oil surface flow visualization. The smoke-laser light sheet visualization, to aid in understanding the oil streak-line patterns, clearly demonstrates that a pair of tornado-like vortices marched along the downstream together with a pair of side tip vortices. A topological sketch to characterize the surface flow and the four vortices emanating from the top surface is included.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.20 no.4
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• pp.1458-1471
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• 1996

The present study is concerned with the heat transfer enhancement associated with a symmetrical or asymmetrical horseshoe vortex in front of and around the circular cylinder centered between the side walls of a wind tunnel. The static pressure measurements and the flow visualization in front of and around cylinders have been performed to determine the existence of horseshoe vortex. The hue-capturing method using the thermochromatic liquid crystals with great spatial resolution was used to obtain the local information of the endwall heat transfer coefficients. In case of one cylinder, the convective heat transfer coefficients of the region where the horseshoe vortex exists are larger than those of any other region. In case of two cylinders with tandem arrangement, the heat transfer rate of gap spacing (d/D= 1.5) is higher than that of gap spacings (d/D=2.0 or 2.5).

• Journal of the Korea institute for structural maintenance and inspection
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• v.8 no.4
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• pp.231-238
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• 2004

This paper presents the tensile behavior of the stud connection between reinforced concrete(RC) and steel members. Hanger reinforcements are placed around the studs to transfer the tensile and flexural loads to the opposite side of the concrete member. Eight specimens for the tensile tests are tested with variables, which are the arrangement details of hanger reinforcements, the reinforcing bars, and the embedment length of stud. The results of the tensile tests show that hanger reinforcements are effective to increase tensile strength for stud connections. Hangers and reinforcing bars near stud bolts contributed to the reduction of brittle failure. From the evaluation on the tensile strength by previous design guidelines, it was shown that CCD (Concrete Capacity Design) method was more suitable for estimation of test strength.

• Journal of the Korean Wood Science and Technology
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• v.13 no.1
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• pp.3-18
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• 1985

In Korea, a study on the anatomical features of pitch pine (pinus rigida Miller) branch wood through photo-microscopical method was reported in 1972 by Lee. Therefore, as a further study of Lee's on the anatomical features in branch wood of pinus rigida miller that grows in Korea, compression wood, opposite wood, and side wood were selected and treated for the purpose of comparing their structures revealed on cross and radial surface through scanning electron microscope in this study. The obtained results in this study were summarized as follows; 1. The trachied transition from earlywood to late wood is very gradual and the tracheids are nearly regular in both arrangement and size in compression wood but this transition in opposite wood and side wood is abrupt and the tracheids in opposite wood and side wood are less regular than those in compression wood. Also, the annual ring width of opposite wood is narrower than that of compression wood or side wood and the rays revealed on cross surface of side wood are more distinct than compression wood and opposite wood rays. 2. The tracheids of compression wood show roundish trends especially in earlywood but those of opposite wood and side wood show some angular trends. And intercellular space, helical cavity, and spiral check are present in both earlywood and latewood of compression wood but not present in opposite wood and side wood irrespective of earlywood and latewood. 3. The wall thickness of latewood tracheid is similar to that of earlywood tracheid in compression wood whereas the wall thickness of latewood tracheid is by far thicker than that of earlywood tracheid in opposite wood and side wood and the S3 layer of secondary wall is lack in compression wood tracheid unlike opposite wood and side wood tracheid. 4. The tracheids in compression wood are often distorted at their tips unlike those in opposite wood and side wood and the bordered pit in compression wood tracheid is located at the bottom of helical groove unlike that in opposite wood and side wood tracheid. 5. The bordered pits in radial wall of opposite wood and side wood tracheids are oval in shape but those of compression wood tracheids show some modified oval shape. 6. In earlywood of side wood, the small apertures of cross-field pits are roundish triangle to rectangle and the large one are fenestriform through the coalition of two small ones. However, the small apertures of cross-field pits are upright oval and the large ones are procumbent oval shape in earlywood of opposite wood and the apertures of cross-field pits in compression wood are tilted bifacial convex lens shape in earlywood and slit in late wood because of the border on tracheid side.

• 유체기계공업학회:학술대회논문집
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• 2006.08a
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• pp.327-330
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• 2006

This paper represents the numerical analysis on effects of radius ratio in a concentric annulus with a rotating inner cylinder. The numerical model consisted of two cylinder which inner cylinder is rotating and outer cylinder is fix, and the axial direction is used the cyclic condition because of the length for axial direction is assumed infinite. The diameter of inner cylinder is assumed 86.8mm, the numerical parameters are angular velocity and radius ratio. Also, the whole walls of numerical model have no-slip and the working fluid is used water at $20^{\circ}C$. The numerical analysis is assumed the transient state to observe the flow variations by time and the 3-D cylindrical coordinate system. The calculation grid adopted a non-constant grid for dense arrangement near the wall side of cylinder, the standard $k-{\omega}$ high Reynolds number model to consider the effect of turbulence flow and wall, the fully implicit method for time term and the quick scheme for momentum equation. The numerical method is compared with the experimental results by Wereley and Lueptow, and the results are very good agreement. As the results, TVF isn't appeared when Re is small because of the initial flow instability is disappear by effect of the centrifugal force and viscosity. The vortex size is from 0.8 to 1.1 for TVF at various $\eta$, and the traveling distance for wavy vortex have the critical traveling distance for each case.

• Journal of the Institute of Electronics and Information Engineers
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• v.51 no.4
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• pp.181-190
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• 2014

The underwater acoustic lens system is one of the systems getting high-resolution images on the seafloor by the beam forming method using acoustic lens. The beam forming using acoustic lenses reduces complexity and driving power. When receiving an incoming beam with the acoustic lens array, beam pattern analysis and arrangement problem of the array sensor must be addressed. Introducing SIR (Signal to Interference Ratio), the relationship among sensor interval, beam pattern and image quality would be analyzed. Generally if the sensor interval getting wider, the less effect of the side lobes makes SIR high. If the amplitude of a side lobe is high, SIR is generally getting low. The type of the apodization function changes the width, shape and amplitude of both main lobe and side lobes. Thus an appropriate apodization function can improve SIR. In this paper, SIR is stable at the sensor interval of 13mm with 0-10dB, which is not high relatively. By applying the Chebyshev function, the SIR becomes 80dB over the sensor interval of 37 mm or higher. The Hann and triangular functions demonstrate better SIR when the sensor interval becomes narrower.

• The Journal of the Korea institute of electronic communication sciences
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• v.17 no.2
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• pp.265-278
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• 2022

The global energy paradigm is rapidly changing by centering on carbon neutrality, and wind energy is positioning itself as a leader in renewable energy-based power sources. The success of onshore and offshore wind energy projects focuses on securing the economic feasibility of the project, which depends on securing high-quality wind resources and optimal arrangement of wind turbines. In the process of constructing the wind farm, the optimal arrangement method of wind turbines considering the main wind direction is important, and this is related to minimizing the wake effect caused by the fluid passing through the structure located on the windward side. The accuracy of the predictability of the wake effect is determined by the wake model and modeling technique that can properly simulate it. Therefore, in this paper, using WindSim, a commercial CFD model, the wake diffusion pattern is analyzed through the sensitivity study of each wake model of the proposed onshore wind farm located in the mountainous complex terrain in South Korea, and it is intended to be used as basic research data for wind energy projects in complex terrain in the future.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.27 no.2
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• pp.203-211
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• 2009

With supply of the domestic digital camera, the relative importance of the digital camera is coming to be high gradually on aerial photogrammetry, the image of digital camera is more applied in image map or digital topographic map production. But, there are cases that do not have position information or attitude information of each photograph in digital camera results. Therefore, we wish to present additional method to get more accurate photograph control point result. In this study, One is called A method, which is the case of entering positioning information of principal point from topographic map as default values that are need to extract tie point automatically using by 56 pieces of photography that are photographed by DMC to the extent to 5 courses and 35 GCP points. The other is called B-method, which is the case of entering exterior orientation parameters that are processed by block adjustment for A-method using by 4 control points in method-1 as default values. We have analyzed about results per control points arrangement for two cases using MATCH-AT that is photograph control point measurement S/W of Germany INPHO company. As a result of analysis, accuracy of B-method was better than that of A-method, and we could get more accurate results if block adjustments are executed including self calibration. Also, it is more effective in expense side that using self calibration for photograph survey in B-method because can reduce GCP numbers.

• Korean Institute of Interior Design Journal
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• v.21 no.4
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• pp.21-30
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• 2012

Interior space of modern society has a request for non-functional considerations as well as a need for function. French sociologist Jean Baudrillard defined this phenomenon as a dialectical relationship between the functional system and the non-functional system in his book "The System of Objects". The main goal of interior design is the pursuit of non-functional aspects which can satisfy emotional needs of human being without ignoring functional side. This means that designer should exceed the limitation of the functional system and overcome it by his own idea and method. Under this recognition, this paper tried to understand how Shiro Kuramata and Takashi Sugimoto accomplished the overcoming successfully. Sugimoto breaks through mechanical monotony introducing the non-functional objects into the functional system. His objects have power and form of the nature. They also shows traces of manufacture and labor. They works as media transferring old life and values. Sugimoto sometimes adopts the non-functional system such as collection, so it reveals time of collecting and arrangement of various objects. In contrast to Sugimoto, Kuramata erased the form of functional object and turned over the everydayness of the functional system. Instead, aesthetical phenomena substitutes form. Having doubts about the geometrical order of functional system, he opened a discourse for its meaning and limitation. However they have something in common which works as a blueprint for establishing subject's discourse. This discourse is comprised of their own memories of scenes. These subjects' discourse institute worlds through their design works based on each methodology. From the Heideggerian point of view, the worlds offer a foundation which allows the establishment of art in interior design.

• Journal of the Korean Institute of Rural Architecture
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• v.17 no.4
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• pp.49-56
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• 2015

This study aims to identify variables (dependent and independent variables) by plane type and area, focusing on the R.C structure planes which were applied to the National Rental Housing Complexes during the 1970-80s; and to investigate differences in residential space compositions depending on the interrelationship between the variables. The results of this study can be summarized as follows: First, an independent variable which had the most influence on the residential space composition was found to be stairs. As dependent variables, bedroom, livingroom, and kitchen showed difference in spatial arrangements. Second, in the case of the front entry type, one-sided arrangements were the most common for the 3L+D.K composition, because livingroom was arranged near the stairs, Disadvantages were: (1) the spatial division of each room was not efficient; and (2) the use of room space was low due to long access to each room. Third, in the case of the rear entry type, no problem was found in arranging bedrooms on the front side. By arranging livingroom as a common space area, the distance of approachability to each room was found to be short and the use of space was excellent. However, disadvantages were: (1) stability was lacking; and (2) privacy was low. Fourth, depending on the location of the stairs, an interaction between bedrooms and the connectivity between livingroom and kitchen were found. Accordingly, there were differences in the size and arrangement of space by plane type.