• Structural Engineering and Mechanics
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• v.46 no.3
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• pp.323-335
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• 2013

This work aims to study the effect of stiffener ties in the behavior of intermediate length open section Cold-Formed Steel (CFS) Columns under axial compression. A comparative study on the behaviour and strength of Cold Formed Steel Columns by changing the direction of projection of lips (i.e., inwards or outwards) are also done. In this work two types of sections were considered Type-I section with lip projecting outwards (hat) and Type-II section with lip projecting inwards (channel). The length of the columns is predicted by performing elastic buckling analysis using CUFSM software. The theoretical analysis is performed using DSM - S100;2007, AS/NZ: 4600-2005 and IS: 801-1975. The compression tests are carried out in a 400 kN loading frame with hinged-hinged end condition. The non-linear numerical analysis is performed using Finite Element software ANSYS 12.0 to simulate the experimental results. Extensive parametric study is carried out by varying the width and spacing of the stiffener ties. The results are compared; the effects of stiffener ties on behaviour and load carrying capacity on both types of columns are discussed.

• Advances in Computational Design
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• v.3 no.1
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• pp.71-86
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• 2018

Thin-walled cross-sections can be optimized to enhance their resistance and progress their behaviour, leading to more competent and inexpensive structural system. The aim of this study is to afford a methodology that would facilitate progress of optimized cold formed steel (CFS) column section with maximum ultimate strength for practical applications. The proposed sections are designed to comply with the geometrical standards of pre-qualified column standards for CFS structures as well as with the number of industrialized and practical constraints. The stiffening evaluation process of CFS lipped channel columns, a five different cross section are considered. The experimental strength and behaviour of the proposed sections are verified by using the finite element analysis (FEA). A series comprehensive parametric study is carried out covering a wide range of section slenderness and overall slenderness ratio of the CFS column with and without intermediate web stiffeners. The ultimate strength of the sections is determined based on the Direct Strength Specification and other design equation available from the literature for CFS structures. A modified design method is proposed for the DSM specification. The results indicate that the CFS column with complex edge and intermediate web stiffeners provides an ultimate strength which is up to 78% higher than standard optimized shapes with the same amount of cross sectional area.

• 한국전산유체공학회:학술대회논문집
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• 2008.03b
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• pp.514-517
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• 2008

An hydraulic experiment was carried out in an open channel flume in order to investigate the water discharge capability of the sluice caisson for tidal power generation, which greatly affects the economical efficiency of the construction of a tidal power plant. To predict the influence of change in the major design parameters relating to the sluice shape on the water discharge capability of the sluice, the experiment was carried out very precisely. The experiment was carried out for the six different sluice models of different widths and bottom heights of the sluice throat section. The experimental data showed that the water discharge generally increased by increasing the width of the throat section if the side shape of the sluice was the same. In addition, the coefficient of discharge was larger when the bottom height of the throat section was higher for the two bottom heights that were tested.

• 한국지구물리탐사학회:학술대회논문집
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• 2007.06a
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• pp.157-162
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• 2007

Geophysical survey has been conducted on the continental margin off the South Shetland Islands aboard R/V Onnuri of KORDI in 1992/1993. About 800-line km of 96-channel reflection data have been acquired. On the seismic section, BSR with strong reflectivity and negative polarity has been found at 700 ms below the sea bottom. BSR is considered as the base of gas hydrates and AVO analysis was performed to study physical properties along BSR. True amplitude recovery and surface consistence amplitude were applied to seismic data and angle gathers were obtained. AVO gradient and AVO intercept are calculated on every CDP gather. Section of AVO intercept show strong reflectivity and negative polarity on BSRs and stronger continuity of BSR than stacked section. Cross plot of intercept-gradient indicates that the lower layer below BSR is filled with free gas.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.7 no.6
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• pp.1264-1270
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• 2006

In this study, semi-two dimension numerical model(GSTARS 2.1 model) were applied to study on the hydraulic and sedimentologic characteristics of downstream channel section in Dal stream. GSTARS 2.1 model was applied for the four selected sediment transport formulas(Meyer-Peter and Muller, Acker and White's, Engelund and Hanson, Yang formula) from 1984 to 1992 measured data on each section. The simulation results of Meyer-Peter and Muller formula for long-term bed changes are good when compared to the measured data. When quantitatively compared, it appears that the results data is relatively underestimated compared to the 1992 measured data on each section. Using Meyer-Peter and Muller formula, analyse the effects of bed changes by stream tube number.

• Nuclear Engineering and Technology
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• v.51 no.7
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• pp.1853-1859
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• 2019

The two-thermocouple method was investigated experimentally to evaluate its accuracy for the measurement of local wall temperature and heat flux on a heat transfer tube with an electric heater rod installed in an annulus channel. This work revealed that a thermocouple flush-mounted in a surface groove serves as a good reference method for the accurate measurement of the wall temperature, whereas two thermocouples installed at different depths in the tube wall yield large bias errors in the calculation of local heat flux and wall temperature. These errors result from conductive and convective changes due to the fin effect of the thermocouple sheath. To eliminate the bias errors, we proposed a calibration method based on both the local heat flux and Reynolds number of the cooling water. The calibration method was validated with the measurement of local heat flux and wall temperature against experimental data obtained for single-phase convection and two-phase condensation flows inside the tube. In the manuscript, Section 1 introduces the importance of local heat flux and wall temperature measurement, Section 2 explains the experimental setup, and Section 3 provides the measured data, causes of measurement errors, and the developed calibration method.

• Journal of the Korean Institute of Telematics and Electronics
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• v.23 no.5
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• pp.719-725
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• 1986

Reed-solomon(R-S) code is very effective to coerrect both random and burst errors over a noise communication channel. However, the required hardware is very complex if the B/M algorithm was employed. Moreover, when the error correction system consists of two R-S decoder and de-interleave, the I/O data bns lines becomes 9bits because of an erasure flag bit. Thus, it increases the complexity of hardware. This paper describes the R-S decoder which consisits of a error correction section that uses a direct decoding algorithm and erasure generation section and a erasure generation section which does not use the erasure flag bit. It can be shown that the proposed R-S dicoder is very effective in reducing the size of required hardware for error correction.

• Journal of the Korean Association of Geographic Information Studies
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• v.25 no.4
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• pp.136-150
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• 2022

In this study, a comparative review was conducted on how to use RGB images to obtain river topographic information, which is one of the most essential data for eco-friendly river management and flood level analysis. In terms of the topographic information of river zone, to obtain the topographic information of flow section is one of the difficult topic, therefore, this study focused on estimating the river topographic information of flow section through RGB images. For this study, the river topography surveying was directly conducted using ADCP and RTK-GPS, and at the same time, and orthomosiac image were created using high-resolution images obtained by drone photography. And then, the existing developed regression equations were applied to the result of channel topography surveying by ADCP and the band values of the RGB images, and the channel bathymetry in the study area was estimated using the regression equation that showed the best predictability. In addition, CCHE2D flow modeling was simulated to perform comparative verification of the topographical informations. The modeling result with the image-based topographical information provided better water depth and current velocity simulation results, when it compared to the directly measured topographical information for which measurement of the sub-section was not performed. It is concluded that river topographic information could be obtained from RGB images, and if additional research was conducted, it could be used as a method of obtaining efficient river topographic information for river management.

• Korean journal of communication and information
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• v.23
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• pp.153-187
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• 2003

The main purpose of this study was to examine the characteristics of corporate PR practitioners whose opinions were quoted as news sources and of the related articles in the economic section of the nation's three largest newspapers. The results revealed that the PR practitioners were mostly males with the job title of general manager or manager working for large electronics/IT or financing companies in Seoul and near metropolitan areas. In particular, such overwhelming features were more clearly salient in the articles related to conflicts. However, the phenomena seem to have been somewhat eased since 2002 when the newspapers came out with the specialized economic section. Analyzing the articles in terms of the channel of covering news, theme of news, and the existence of any conflict, we found statistically significant differences in the characteristics of PR practitioners. In addition, the comparison between each period before and after the emergence of the specialized economic section also showed statistically significant differences in the characteristics of the PR practitioners in many cases.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.47 no.2
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• pp.91-98
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• 2021

Objectives: Hyaluronoglucosaminidase (hyaluronidase) increases the local intercellular permeability of the peripheral lymphatic channel and capillaries, which may help reduce edema. In the present study, the effects of hyaluronidase on postoperative edema and pain reduction were evaluated. Materials and Methods: The study included 38 patients who underwent guided bone regeneration (GBR) surgery before implantation. Patients were randomly assigned to either the control group (n=20) or the test group (n=18). Hyaluronidase was injected into the GBR site of subjects in the test group. Postoperative edema was evaluated by measuring the distance between specific facial landmarks immediately after surgery (T1) and 2-4 days after surgery (T2). The degree of pain at T2 and at 10-14 days after surgery (T3) was assessed. Results: In the test group, the degree of swelling was lower than in the control group, however, only two measurements, from the tragus to the mouth corner and from the outer canthus to the mouth corner, showed statistically significant differences (P=0.012 and P=0.001, respectively). The anti-edema effect of hyaluronidase was more effective in the maxilla than in the mandible. In the maxilla, the percentage of facial swelling was significant for three measurements. However, in the mandible, the percentage of facial swelling was significant for only one measurement. Low levels of pain that were similar at T2 and T3 were reported in both groups. Conclusion: The results indicate the degree of swelling was lower in the test group and hyaluronidase appeared to be more effective in the maxilla. The degree of pain reduction was similar between groups. Further in vivo and randomized controlled trials with larger sample sizes are warranted.