• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.24 no.4
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• pp.164-171
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• 1988

Recently with the rapid development in marine and shipbuilding industries such as marine structures, ships and chemical plants, it takes much interest in the study of corrosion fatigue characteristics that was close up an important role in mechanical design. In this study, characteristics of corner crack propagation on the base metal and heat affected zone of 5086 Al-Alloy was tested by using of a rotary bending fatigue tester and was investigated under the environments of specific resistance, $\rho$=25$\Omega$ cm and air. The corrosion fatigue crack initiation and corrosion fatigue life sensitivity were quantitatively inspected for 5086 Al-Alloy in the specific resistance, $\rho$=25$\Omega$ cm. Main results obtained are as follows: (1) The corrosion sensitivity of heat affected zone under specific resistance, $\rho$=25$\Omega$cm shows approximately 1.69~2.22 and corrosion sensitivity of base metal is more susceptible than that of heat affected zone. (2) The corrosion fatigue life sensitivity on heat affected zone decreases eminently than that of initial corrosion fatigue crack. (3) The characteristics of quarter elliptical corner crack propagation shows that depth crack is more grown than surface crack at crack initiation, but the surface crack is more propagated than depth crack as the crack propagation is increased. (4) The surface crack and depth crack growth on heat affected zone by softness show delayed phenomenon than that of base metal.

• Proceedings of the Zoological Society Korea Conference
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• 2000.10a
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• pp.160.2-160
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• 2000

No Abstract, See Full Text

• Journal of the speleological society of Korea
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• no.8
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• pp.43-54
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• 1998

The plant life of caves is made up of species that can live in total darkness. If any plant in a cave contains chlorophyll, the chlorophyll obviously cannot be energized by light rays from th sun. With a few exceptions noted below, none of the plants in the perpetually dark zone contains chlorophyll. The chief plant life there consists of bacteria, including actinomycetes, and fungi.(omitted)

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.25 no.2
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• pp.87-104
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• 1989

Recently, with the tendency of more lightening, high-strength and high-speed in the marine industries such as marine structures, ships and chemical plants, the use of the aluminium Alloy is rapidly enlarge and there occurs much interest in the study of corrosion fatigue crack characteristics. In this paper, the initiation of surface crack and the propagation characteristics on the base metal and weld zone of 5086-H116 Aluminium Alloy Plate which is one of the Al-Mg serious alloy(A5000serious) used most when building the special vessels, were investigated by the plane bending corrosion fatigue under the environments of marine, air and applying cathodic protection. The effects of various specific resistances on the initiation, propagation behavior of corrosion fatigue crack and corrosion fatigue life in the base metal and heat affected zone were examined and its corrosion sensitivity was quantitatively obtained. The effects of corrosion on the crack depth in relation to the uniform surface crack length were also investigated. Also, the structural, mechanical and electro-chemical characteristics of the metal at the weld zone were inspected to verify the reasons of crack propagation behavior in the corrosion fatigue fracture. In addition, the effect of cathodic protection in the fracture surface of weld zone was examined fractographically by Scanning Electron Microscope(S.E.M.). The main results obtained are as follows; (1) The initial corrosion fatigue crack sensitibity under specific resistance of 25Ω.cm% show 2.22 in the base metal and 19.6 in the HEZ, and the sensitivity decreases as specific resistance increases (2) By removing reinforcement of weldment, the initiation and propagation of corrosion crack in the HAZ are delayed, and corrosion fatigue life increases. (3) As specific resistance decreases, the sensitivity difference of corrosion fatigue life in the base metal and HAZ is more susceptible than that of intial corrosion fatigue crack. (4) Experimental constant, m(Paris' rule) in the marine environment is in the range of about 3.69 to 4.26, and as specific resistance increases, thje magnitude of experimental constant, also increases and the effect by corrosion decreases. (5) Comparing surface crack length with crack depth, the crack depth toward the thickness of specimen in air is more deeply propagated than that in corrosion environment. (6) The propagation particulars of corrosion fatigue crack for HAZ under initial stress intensity factor range of $\Delta$k sub(li) =27.2kgf.mm super(-3/2) and stress ratio of R=0 shows the retardative phenomenon of crack propagation by the plastic deformation at crack tip. (7) Number of stress cycles to corrosion fatigue crack initiation of the base metal and the welding heat affected zone are delayed by the cathodic protection under the natural sea water. The cathodic protection effect for corrosion fatigue crack initiation is eminent when the protection potential is -1100 mV(SCE). (8) When the protection potential E=-1100 mV(SCE), the corrosion fatigue crack propagation of welding heat affected zone is more rapid than that of the case without protection, because of the microfissure caused by welding heat cycle.

• Journal of Mechanical Science and Technology
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• v.20 no.12
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• pp.2159-2167
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• 2006

In order to find out a physical quantity which controls the fatigue life of a structure and to predict the fatigue life of tires, a finite element simulation methodology to use the cracking energy density (CED) and the virtual crack closure technique (VCCT) was proposed and applied to three different tires of a similar size. CED was calculated to predict the location of a crack initiation, and VCCT was used to obtain the strain energy release rate (SERR) at the tip of an initiated crack. Finite element simulations showed that SERR oscillated in the circumferential direction with its minimum occurring just before the contact zone and its maximum occurring just after the center of the contact zone, and SERR was affected significantly by the frictional force acting on the crack surface. In addition, a durability test was conducted to measure the fatigue life of the three tires. The comparison of SERR values with the test data revealed that the fatigue life increased as the amplitude of SERR decreased or as the R-ratio of SERR increased.

• Journal of Environmental Impact Assessment
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• v.9 no.3
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• pp.185-202
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• 2000

Uncertainty and variability in Life Cycle Assessment(LCA) have been significant key issues in LCA methodology with techniques in other research area such as social and political science. Variability is understood as stemming from inherent variations in the real world, while uncertainty comes from inaccurate measurements, lack of data, model assumptions, etc. Related articles in this issues were reviewed for classification, distinguish and elaboration of probabilistic/stochastic health risk analysis application in LCA. Concept of focal zone, streamlining technique, scenario modelling and Monte Carlo/Latin Hypercube risk analysis were applied to the uncertainty/variability analysis of health risk in LCA. These results show that this general framework of multi-disciplinary methodology between probabilistic health risk assessment and LCA was of benefit to decision making process by suppling information about input/output data sensitivity, health effect priority and health risk distribution. There should be further research needs for case study using this methodology.

• Food Science and Biotechnology
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• v.17 no.5
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• pp.1106-1109
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• 2008

The anti-Helicobacter pylori activity, cytotoxicity, and anti-inflammatory activity of white ginseng extract (WGE) were investigated in vitro in this study. The antimicrobial effects of WGE toward H. pylori strains 52 J99, SSI, and 51 were tested using the disk diffusion method. Among these H. pylori strains, H. pylori 52 was the most sensitive, having the largest inhibition zone (19 mm), followed by J99, SSI, and 51. The zone of inhibition due to WGE increased significantly with increasing dosage. The cytotoxicity of WGE toward the human cancer cell lines A-549 (human lung carcinoma), HEC-1-B (human endometrial adenocarcinoma), HeLa (human uterin adenocarcinoma), and SW-156 (human kidney carcinoma) was measured using the 3-(4,5-dimethylthizol-2-yl)-2,5-diphenylate-tetrazolium bromide (MTT) assay. WGE exhibited an inhibitory effect on cell growth at 2.0 mg/mL for all tumor cell lines. An analysis of anti-inflammatory activity using the RAW 264.7 cell line showed that the inhibition of nitric oxide (NO) production increased as the WGE content increased. These results demonstrate the potential of WGE to be used as a health-promoting substance.

• Journal of the Korean Wood Science and Technology
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• v.48 no.6
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• pp.896-906
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• 2020

Wood deterioration experiments were carried out for 6 months in an intertidal zone of South Korea to monitor the changes in the chemical properties of two types of species, Korean red pine and sawtooth oak. The results of FT-IR spectra and XRD patterns have shown that the chemical properties of the wood did not change significantly during the 6-month burial period. However, the brightness of the surface decreased after burial; the value of the sawtooth oak sample was lower than that of the Korean red pine sample owing to an accumulation of inorganic compounds in cell lumen as observed by ICP analysis. Among the inorganic compounds, sodium and sulfur concentrations increased significantly over the burial period compared with the control. Further, the maximum moisture content decreased from 199% to 136% in the Korean red pine and 62% to 60% for the sawtooth oak. Nevertheless, the major chemical composition of both the wood species did not change significantly during the 6-month burial period, whereas, the crystallinity decreased with an increasing burial period owing to an accumulation of inorganic compounds in the lumen.

• Structural Engineering and Mechanics
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• v.57 no.3
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• pp.403-423
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• 2016

The challenges involved with fatigue damage assessment of steel catenary riser (SCR) in the touchdown zone (TDZ) are primarily due to the non-linear behaviour of the SCR-seabed interaction, considerable uncertainty in SCR-seabed interaction modelling and geotechnical parameters. The issue of fatigue damage induced by the cyclic movements of the SCR with the seabed has acquired prominence with the touch down point (TDP) interaction in the TDZ. Therefore, the SCR-seabed response is critical for reliable estimation of fatigue life in the TDZ. Various design approaches pertaining to the lateral pipe-soil resistance model are discussed. These techniques have been applied in the finite element model that can be used to analyse the lateral SCR-seabed interaction under hydrodynamic loading. This study investigates the sensitivity of fatigue performance to geotechnical parameters through a parametric study. In this study, global analyses are performed to assess the influence of vertical linear seabed springs, the lateral seabed model and the non-linear seabed model, including trench evolution into seabed, seabed normalised stiffness, re-penetration offset parameter and soil suction resistance ratio, on the fatigue life of SCRs in the TDZ.

• ALGAE
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• v.22 no.3
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• pp.201-207
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• 2007

For getting primary cue of restoration, the algal flora and intertidal community structure of Deokjeokdo, Yeonpyeongdo and Ganghwado were investigated for from February to November 2006. The total of 28 species, including five Chlorophytes, five Phaeophytes, 17 Rhodophytes and one sea grass were identified. The occurrence of species according to sampling site was 22 species in Deokjeokdo, seven species in Yeonpyeongdo and four species in Ganghwado. Among them Gloiopeltis furcata, Ulva pertusa and Sargassum horneri in Deokjeokdo, Scytosiphon lomentaria in Yeonpyeongdo, Enteromorpha prolifera in Ganghwado were ominants. The algal zonation of intertidal zone was figured out by Gloiopeltis furcata, Caulacanthus okamurae – Corallina pilulifera – Ulva pertusa, Ahnfeltiopsis flabelliformis, Sargassum horneri, Undaria pinnatifida in Deokjeokdo, Bangia atropurpurea – Scytosiphon lomentaria – Ahnfeltiopsis flablleiformis in Yeonpyeongdo from upper to lower zone and Enteromorpha prolifera, Enteromorpha linza – Sargassum thunbergii, Myelophycus simplex in Ganghwado from middle to lower zone. The average of biomass was measured as 80.6 g dry wt. m–2 in Deokjeokdo, 32.2 g dry wt. m–2 in Yeonpyeongdo and less than 1 g dry wt. m–2 in Ganghwado.