• Journal of the Korean Society for Nondestructive Testing
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• v.16 no.3
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• pp.174-183
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• 1996

Acoustic emission(AE) response during stress corrosion cracking(SCC) of Inconel 600 alloy has been monitored to study the AE detectability of crack generation and growth by comparing the crack behavior with AE parameters processed, and to evaluate the applicability as a nondestructive evaluation(AE) by measuring the minimum crack size detectable with AE. Variously heat-treated specimens were tensioned by constant extension rate test(CERT) in various extension rate to give rise to the different SCC behavior of specimens. The AE amplitude level generated from intergranular stress-corrosion cracking(IGSCC) is higher than those from ductile fracture and mechanical deformation, which means the AE amplitude can be a significant parameter for distinguishing the An source. AE can also provide the effective means to identify the transition from the small crack initiation and formation of dominant cracks to the dominant crack growth. Minimum crack size detectable with AE is supposed to be approximately 200 to $400{\mu}m$ in length and below $100{\mu}m$ in depth. The test results show that AE technique has a capability for detecting the early stage of IGSCC growth and the potential for practical application as a NDE.

• Korean Journal of Environmental Biology
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• v.34 no.3
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• pp.212-215
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• 2016

We developed a new ecotoxicological test method using native test species, eggs of Ephemera orientalis, and five kinds of industrial wastewater were tested to validate the test method. The water samples were collected in Jun 2006 from the following industries: pesticide, metal plating, PCB, leather1, and leather2. Wastewater and effluent were diluted by distilled water, respectively, to prepare various concentrations, 100, 50, 25, 12.5, 6.3, 3.1, and 0%. For the egg bioassay, 20 freshly laid eggs (<24 h old) were exposed to test solutions in a Petri dish ($52{\times}12mm$) at $20^{\circ}C$ with photoperiod of 16 h light and 8 h dark for 14 days. The median egg hatching concentrations (EHC50) were estimated using Probit analysis. All EHC50s of wastewater were less than 3.1%, which meant very high ecotoxicity except for the wastewater of PCB industry having 6.1% of EHC50. Among the effluents, the least toxic effluent was from pesticide industry having 58% of EHC50, while the effluent of leather2 was the most toxic having 7.3% of EHC50.

• Journal of Gastric Cancer
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• v.6 no.2
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• pp.69-75
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• 2006

Purpose: We aimed to investigate the effect of oral Saccharomyces cerevisiae Hansen CBS 5926 therapy (Saccharomyces boulardii) on gastrointestinal symptoms and nutrition in gastrectomized patients. Materials and Methods: Ninety patients who underwent a gastrectomy due to early gastric cancer were randomly divided into case and control (placebo) groups and were given medicine or placebos for 12 weeks. The gastrointestinal symptom rating and the nutritional status were evaluated by using double blind methods at 4, 16, and 20 weeks after discharge. Results: The ratio of males to females was 2.3 : 1, and the mean age was $56.3{\pm}10.2$ years. The numbers of subtotal gastrectomies and total gastrectomies were 69 and 21, respectively. Fourteen (15.6%) patients dropped, of whom 5 belonged to the case group. Of the remaining 76 patients, those in the case group had higher levels of serum albumin (P=0.046). For patients who underwent subtotal gastrectomy (n=57), the case group had higher level of serum albumin (P=0.049). Conclusion: This double blind study showed that oral Saccharomyces boulardii therapy could improve the postoperative nutrition of gastrectomized patients because gastrectomized patients with oral Saccharomyces boulardii therapy had higher levels of serum albumin than the control group.

• Journal of KIISE:Information Networking
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• v.31 no.5
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• pp.438-449
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• 2004

With the growing deployment of network and internet, the importance of security is also increased. But, recent intrusion detection systems which have an important position in security countermeasure can't provide proper analysis and effective defence mechanism. Instead, they have overwhelmed human operator by large volume of intrusion detection alerts. In this paper, we propose an efficient alert analysis system that can produce high level information by analyzing and processing the large volume of alerts and can detect large-scale attacks such as DDoS in early stage. And we have measured processing rate of each elementary module and carried out a scenario-based test in order to analyzing efficiency of our proposed system.

• Composites Research
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• v.13 no.4
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• pp.11-18
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• 2000

This study is mainly concerned with friction and wear properties for the piston ring of non-lubricating air compressor which made of PTFE-polyimide composites. At the PTFE and polyimide alone mixture specimens, PTFE80%-polyimide20%, which shows the lowest mean friction coefficient and specific wear rate at 0.94m/s sliding speed. In case of the specific wear rate, copper30% specimen shows the lowest value of 2.537-5(mm3/Nm) in all specimens. It considered that the friction coefficient is affected by generating speed and quantity of wear film. In case specific wear rate, it is attributed to the fact that the surface hardness of wear film is proportioned to specific wear rate.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.16 no.1
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• pp.39-51
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• 2011

Acute toxicity test and behavioral change analysis of seawater acclimated Japanese medaka were conducted to identify the brine effects on fish by seawater desalination. 7 day acute toxicity test of brine revealed linear concentration-response relationship from 40.0~80.0 psu treatment groups. There was no significant brine effect for 30-40 psu groups and mass mortality was observed from >50 psu exposure (7-day $LC_{50}$=51.4 psu). Images from the real time camera system were analyzed to observe the changes in behavioral patterns of medaka exposed to various salinity. 40.0 and 50.0 psu exposed groups were stabilized in behavioral patterns after 3.1 and 4.6 hours, respectively and 60.0 psu group showed sharp increase in activity during first 12 hours and 50% mortality thereafter. Similar patterns were observed to 70 and 80 psu groups and both experimental groups showed 100% mortality within 12 hours. Acute toxicity test and behavioral patterns showed very similar toxicity results which revealed the increases in mortality and behavioral activities from 50.0 psu. This critical salinity for fish impacts must be implemented to brine discharge strategy by seawater desalination into the coastal area. Also, we recommend that real time camera monitoring system must be a useful tool for early warning of fish toxicity for other applications. This research was funded by Ministry of Land, Transport and Maritime Affairs, Korea.

• Journal of the Korean GEO-environmental Society
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• v.13 no.7
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• pp.13-17
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• 2012

Recently, our ocean development paradigm is changing so that the development focus has been moved from the port facility developments to creating useful marine space. This paradigm accords well with the current green technology and helps the growth of service industries and the development from this paradigm can become a national land mark. Accordingly, the concept of creating marine waste landfill by the development of resource recycling technology has been introduced for eco-friendly space as an artificial island in future. Therefore, this study introduces the reactive vertical drainage method that is to pursue the purification of pollutants as well as stabilization of newly deposited soils in marine environments. To install the reactive vertical drainage piles for more effective feasibility and constructability, placements of drainage mid-layer are considered in the geotechnical viewpoint. Consolidation characteristics were evaluated by standard consolidation tests after several types of model test. As s result, the application of mid-layer drainage is strongly recommended in the reactive vertical drainage to quickly stabilize newly deposited soils. And vacuum consolidation method has better consolidation characteristic than vertical loading method in terms of the settlements predicted by additional stress for further use as an artificial island.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.04a
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• pp.537-540
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• 2008

Up to now, the RC structures have been recognized as being socially semi-permanent. But in recent years there were reports about the cases of early deterioration of RC structures. Most of all pore structure effects on the durability of concrete as well as mechanical properties of concrete. Therefore, in this study, mixing design was proportioned with the water-binder ratio 0.55 binder compositions corresponding to cement without any supplementary materials(OPC), cement with 50% blast-furnace slag replacement (BFS50), cement with 15% fly ash replacement (FA15), and ternary cement with cement, 15% fly ash, and 35% slag replacement (BFS35+FA15). And this study is to compare pore structure property of concrete by carbonation to investigate the effect of the permeation of deterioration factors such as $CO_2$ and chloride ion under the combined deterioration environments. The results showed that pore volume effects on the diffusibility of chloride ion.

• Journal of The Korean Society of Grassland and Forage Science
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• v.32 no.3
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• pp.229-236
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• 2012

This experiment was conducted to evaluate agronomic characteristics and forage productivity of italian ryegrass cultivars at Seongju in the Kyeongbuk from 2010 to 2012. The experiment was arranged in randomized complete block design with three replications. Italian ryegrass cultivars were seeded on Oct. 12 in 2010 and Oct. 3 in 2011. The early-medium maturing cultivars were harvested on 29 Apr. and the medium late ones were harvested on 4 May in 2011. In 2012, the early-medium cultivars were harvested on 28 Apr. and medium late ones were harvested on 12 May. DM (dry matter) yield of the early-medium maturing cultivars 'Yeonbong3', 'Seongnong', 'Winter Hawk', 'Pride' and 'Kowinnearly' was 9,850, 9,778, 9,486, 9,363 and 9,267 kg/ha and DM yield of those were significantly higher (p<0.05) than other seven cultivars or ones. DM yield of the medium-late maturing cultivars 'Tetragold', 'Hwasan 101', 'Jumbo', 'Sungrazer', 'Master', 'SelectIV' and 'KB Royal' was 9,542, 9,492, 9,103, 8,981, 8,903, 8,870 and 8,681 kg/ha and DM yield of those were higher (p<0.05) than other three. Cold tolerance for 'Hwasan 101' was higher than others, in medium-late maturing cultivars. According to the results obtained from this study, it is suggested that early-medium maturing cultivars would be recommendable for DM production.

• Journal of The Korean Society of Grassland and Forage Science
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• v.5 no.3
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• pp.176-179
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• 1985

Digestion trials were conducted to evaluate intake and digestibility of grass harvested at different dates. Silage was prepared from first-growth forage (predominantly timothy) which cutting dates; 4 June (vegetative, called early-cut) and 30 June (heading, called late-cut). The silage was fed to wethers at restricted and ad libitum levels of intake. The crude protein and crude fat of silage decreased with advancing maturity, while contents of fibre increased. DM intake of early-cut and late-cut silage were $99g/W_{kg}^{0.75}\;and\;75g/W_{kg}^{0.75}$, respectively. In digestibility and TDN, significant differences (p<0.01) between early-cut and late-cut silage were found. There was no significant difference in DM digestibility of early-cut silage between restricted and ad libitum feeding, but DM digestibility was decreased markedly in ad libitum feeding that out of account in fecal condition. Digestibility of all composition in early-cut silage, except for hemicellulose, was not observed with increasing levels of intake. Digestibility of crude protein, NDF and hemicellulose in late-cut silage were decreased (p<0.05) in ad libitum when compared with restricted feeding. Results of this study suggest that digestibility of early and late forages harvested as silage varies with levels of intake. Thus, relationship levels of intake and digestibility must be considered cautiously.