• Journal of Korean Society of Steel Construction
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• v.11 no.4 s.41
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• pp.397-407
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• 1999

In this paper, the fatigue safety in the suspension bridge is investigated by using nominal and variable stress, respectively. The technique on structural modeling and the fatigue evaluation using nominal stress are mainly dealt with in this paper. To make the finite element analysis model reflecting the actual structural behavior of the suspension bridge with cross frame, the parametric study is carried out. In this study, the influence of supporting condition. the difference of the results of 2- and 3-D analysis and the number of cross frames modelled in are considered. The nominal stress under the real traffic flow of the bridge is calculated by the combination of the stresses due to the unit DB-24 loading. The nominal stresses for details under consideration are compared with allowable stress ranges specified in the codes and the results are discussed.

• Journal of the Korean Chemical Society
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• v.48 no.2
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• pp.156-160
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• 2004

The extraction rates of plasticizer of LPG high pressure rubber are studied. Submerging solvents are composed of propane, n-butane, n-pentane, n-hexane, n-heptane, propylene, 1,3-butadiene, 1-pentene, 1-hexene, ethanethiol, t-butanethiol, dimethyl sulfide, methyl ethyl sulfide. The relationship between the extraction rate of plasticizer and the descriptors of submerging solvent by using multiple linear regression is as follows; PE(wt%) = 7.5193 - 0.58500Carbon${\sharp}$ + 2.3294DB + 2364SH, (N = 13, F = 24.135, R$^2$ = 0.8894, R$_{adj}^2$ = 0.8526, Variance = 7.588) Plasticizer is well extracted by LPG composed of the high vapour pressure and polarity compounds. The mass of extracted plasticizer becomes increasing in proportion to the contents of thiol sulfur compound and unsaturated hydrocarbon such as propylene and 1,3-butadiene in LPG. While the heavier hydrocarbons are, the less the quantities of plasticizer extracted from rubber are.

• Journal of the Korean GEO-environmental Society
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• v.10 no.7
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• pp.33-41
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• 2009

In the case of underground power utilities pipe such as circular pipe, the most difficult problem is low compaction efficiency of the bottom of pipe inducing the failure of utilities. To overcome this problem, various studies have been performed and one of these is CLSM (controlled low strength materials) accelerated flow ability. CLSM has already been stage of commercial use in the foreign countries led by power company. In this study, we estimated the behavior of flexible pipe with flowable backfill materials and sand to compare on the DB24 load. The results showed that the deformation of flexible pipe is affected by types of backfill materials. CLSM shows better behavior characteristics than compacting sand. But numerical and analytical results that peformed to compare to the field test results showed big gap with the field results.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.36 no.3
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• pp.375-384
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• 2016

In the current Korea highway bridge design code (KHBDC), the criteria of concrete bridge decks are mainly based on short span decks of steel plate girder bridge, there are very little the specific criteria of long span decks in the twin steel plate girder bridge. Therefore, to put more rational and practical design criteria of the long span decks on the code, the complements of the related criteria are required in the current design code. This paper proposed the design bending moments of decks with 6.0~12.0m span for KL-510 load in direction to bridge (longitudinal direction) and perpendicular direction to bridge (transverse direction). The effects of orthotropic concrete decks, stiffness of steel girders and multiple lane loading factors (MLLF) were reflected in the design bending moments. The proposed design bending moments were compared to the design bending moments with DB-24 load.

• Journal of the Korean Institute of Intelligent Systems
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• v.24 no.3
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• pp.310-315
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• 2014

The domestic maritime environment shows higher frequency of maritime accidents amidst greater traffic volume arising from increasing international seaborne trade and maritime leisure activities. To reduce such maritime accidents, there exist various kinds of safety navigation devices in the ship bridge aimed to mitigate burdens of navigators and support their accurate decision making. Amongst is the AIS considered very important, which is an automatic tracking system to assist understanding of the circumstances in the vicinity by receiving information of other ships and also sending its own; where the information contains errors initially, however, such wrong information is periodically transmitted, accordingly giving rise to hindrance sometimes in decision making by shore operators or ship navigators at sea. This study is to propose the error data and field management algorithm using fuzzy theory toward improving reliability and accuracy in ship related information received from AIS.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.04a
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• pp.49-52
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• 2008

The tensile and bond performance of GFRP rebar are different from those of conventional steel reinforcement. It requires some studies on concrete members reinforced with GFRP reinforcing bars to apply it to concrete structures. GFRP has some advantages such as high specific strength, low weight, non-corrosive nature, and disadvantage of larger deflection due to the lower modulus of elasticity than that of steel. Bridge deck is a preferred structure to apply FRP rebars due to the increase of flexural capacity by arching action. This paper focuses on the behavior of concrete bridge deck reinforced with newly developed GFRP rebar. A total of three real size bridge deck specimens were made and tested. Main variable was reinforcement ratio of GFRP rebar. Static test was performed with the load of DB-24 level until failure. Test results were compared and analyzed with ultimate load, deflection behavior.

• Korean Journal of Food Science and Technology
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• v.32 no.5
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• pp.997-1001
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• 2000

The organic acids in 3 kinds of medicinal herbal extracts were screened and compared each other according to their organic acid contents by an efficient gas chromatographic method. It involves solid-phase extraction of organic acids using Chromosorb P with subsequent conversion to stable tert-butyldimethysilyl derivatives for the direct analysis by capillary column gas chromatography and gas chromatography-mass spectrometry. Total of 24 organic acids were reproducibly identified from 3 kinds of herbal extracts. When the GC profiles were simplified to their retention index spectra, characteristic patterns were obtained for each herb sample. As expected, three kinds of herbal extracts showed three distinct patterns.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.24 no.2
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• pp.304-310
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• 2020

The technology in 3D modelling have advanced not only maps, heritages, constructions but also trees modelling. By laser scanning(Faro s350) and photogrammetry software(Pix4d) for 3D modelling, this study compared with real coniferous tree and both technology's results about characteristics of shape, texture, and dimensions. As a result, both technologies all showed high reproducibility. The scanning technique showed very good results in the reproduction about bark and leaves. Comparing the detailed dimensions on it, the error between the actual tree and modelling with scanning was 1.7~2.2%, and the scanning result was larger than the actual tree. The error between the actual tree and photogrammetry was only 0.2~0.5%, which was larger than the actual tree. On the other hand, the dark areas's modelling was not fully processed. This study is meaningful as a basic research that can be used for tree DB on BIM for the landscape architecture, landscape design and analysis with AR technology, historical tree and heritage also.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.28 no.5A
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• pp.719-727
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• 2008

The tensile and bond performance of GFRP rebar are different from those of conventional steel reinforcement. It requires some studies on concrete members reinforced with GFRP reinforcing bars to apply it to concrete structures. GFRP has some advantages such as high specific strength, low weight, non-corrosive nature, and disadvantage of larger deflection due to the lower modulus of elasticity than that of steel. Bridge deck is a preferred structure to apply FRP rebars due to the increase of flexural capacity by arching action. This paper focuses on the behavior of concrete bridge deck reinforced with newly developed GFRP rebars. A total of three real size bridge deck specimens were made and tested. Main variables are the type of reinforcing bar and reinforcement ratio. Static test was performed with the load of DB-24 level until failure. Test results were compared and analyzed with ultimate load, deflection behavior, crack pattern and width.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.28 no.1A
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• pp.39-49
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• 2008

Dynamic responses of steel plate girder bridges considering road surface roughness of bridge and bridge-vehicle interaction are investigated by numerical analysis. Simply supported steel plate girder bridges with span length of 20 m, 30 m, and 40 m from "The Standardized Design of Highway Bridge Superstructure" published by the Korean Ministry of Construction are used for bridge model and the road surface roughness of bridge decks are generated from power spectral density(PSD) function for different road. Three different vehicles of 2- and 3-axle dump trucks, and 5-axle tractor-trailer(DB-24), are modeled three dimensionally. For the bridge superstructure, beam elements for the main girder, shell elements for concrete deck, and rigid links between main girder and concrete deck are used. Impact factor and DLA of steel plate girder bridges for different spans, type of vehicles and road surface roughnesses are calculated by the proposed numerical analysis model and compared with those specified by several bridge design codes.