• 한국균학회소식:학술대회논문집
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• 2014.10a
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• pp.48-48
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• 2014

Arbuscular Mycorrhizal Fungi(AMF) is widespread symbiont forming mutualistic relationship with plant root in terrestrial forest in ecosystem. They provide improved absorption of nutrient and water, and enhance the resistance against plant pathogen or polluted soil, therefore AM fungi are important for survival and maintaining of individual or community of plant. For last decade, many studies about the functional variation of AM fungi on host plant growth response were showed that different geographic isolates, even same species, have different effect on host plant. However, little was known about functional variation of AM fungal isolates originated single population, which provide important insight about intraspecific diversity of AMF and their role in forest ecosystem. In this study, four AM fungal isolates of Rhizophagus clarus were cultured in vitro using transformed carrot (Daucus carota) root and they showed the difference between isolates in ontogenic characteristics such as spore density and hyphal length. The plant growth response by mycorrhizas were measured also. After 20 weeks from inoculation of these isolates to host plants, dry weight, Root:Shoot ratio, colonization rates and N, P concentration of host plant showed host plant was affected differently by AM fungal isolates. This results suggest that AM fungi have high diversity in their functionality in intraspecific level, even in same population.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.22 no.1
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• pp.1-6
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• 1977

The varietal differences of protein content in barley grain and its variation under different cultural conditions were studied. The varietal variation of protein content was significant with the range of 8～18%. The protein content of barley grain were increased by heavier nitrogen application and decreased by shading treatment and drill seeding. There was negative correlation between protein content and grain weight in hulled barley, while positive correlation between nitrogen content of plant and leaf at heading stage and protein content of barley grain was significant in Haganemugi and Buheung.

• The Journal of Fisheries Business Administration
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• v.52 no.3
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• pp.27-38
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• 2021

This study is aimed to figure out the productivity and variability of cage-aquaculture changes. According to the analysis, the productivity of major fish species has been increasing, except mullet. Although the regional productivity has decreased in the last two years, it has been on the rise considering as a whole. Gyeongsangnam-do showed the highest level of productivity by region. Productivity by species was also higher than other regions in the cases of rock fish, mullet and sea bream followed by productivity of Chungcheongnam-do. The production of marine cage-culture in Jeollanam-do is the second largest in Korea in value/weight while its productivity is lower than that of Chungcheongnam-do. When it comes to comparison by region, Gyeongsangnam-do shows the lowest productivity variation. And Jeollanam-do shows the second-lowest variation in productivity that is only about half of that of Chungcheongnam-do province. Thus, it is found that Jeollanam-do region has an advantage in management stability while its productivity is low. On the other hand, productivity by species was also analyzed. Gyeongsangnam-do has the highest productivity by species for rock fish, mullet and sea bream whereas rock bream productivity is the highest in Jeollanam-do. Therefore, it probably needs to reflect these results when choosing regional-focused incubation fish species.

• Korean Journal of Applied Biomechanics
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• v.33 no.1
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• pp.34-44
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• 2023

Objective: The purpose of this study was to examine the effects of increasing running speed on human stability by comparing the Lyapunov Exponent (LyE) and Coefficient of Variation (CV) methods, with the goal of identifying key variables and uncovering new insights. Method: Fourteen adult males (age: 24.7 ± 6.4 yrs, height: 176.9 ± 4.6 cm, weight: 74.7 ± 10.9 kg) participated in this study. Results: In the CV method, significant differences were observed in ankle (flexion-inversion/eversion; p < .05) and hip joint (internal-external rotation; p < .05) movements, while the center of mass (COM) variable in the coronal axis movements showed a significant difference at the p < .001 level. In the LyE method, statistical differences were observed at the p < .05 level in knee (flexion-extension), hip joint (internal-external rotation) movements, and COM across all three directions (sagittal, coronal, and transverse axis). Conclusion: Our results revealed that the stability of the human body is affected at faster running speeds. The movement of the COM and ankle joint were identified as the most critical factors influencing stability. This suggests that LyE, a nonlinear time series analysis, should be actively introduced to better understand human stabilization strategies.

• Proceedings of the KIEE Conference
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• 2008.04c
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• pp.83-85
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• 2008

This paper deals with design and dynamic analysis of electromagnets for levitation applications. On the basis of equivalent magnetic circuit (EMC) method and 3-D finite element analysis (FEA) model, initial and detailed design for electromagnets are performed. Using the state equation for the closed-loop control, the dynamic analysis of electromagnets is also performed. Finally, this paper investigates the variation of levitation force according to current under fixed nominal air-gap, and the variation of required current according to load weight in order to maintain the nominal air-gap. From these results, the validation of design and dynamic analysis of electromagnets is confirmed. In particular, the influence of winding temperature on levitation control is discussed in detail.

• Proceedings of the Korean Geotechical Society Conference
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• 2000.03b
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• pp.655-662
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• 2000

This study concerns with the variation of engineering characteristics of soft ground under embankment treated vertical drains. The derived engineering characteristics can be used in the prediction of increased strength of soft ground treated with vertical drains. The variations of physical properties such as liquid limit, natural water content, void ratio, and dry unit weight, and mechanical properties such as strength, preconsolidation ratio, compressibility are analysed and suggested. The co-relation of physical properties and mechanical properties with installation of vertical drains in soft ground are derived in this study.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.06a
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• pp.1547-1550
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• 2005

ISB panel, inner structured of metal in two skin and bonded, has inner structures which have low relative density, stiffness and strength with low weight of make improvement for that purpose. A kind of Inner structures have various structure types. In this paper, we have studied the Forming Limit Diagram(FLD), thickness variation and stress strain to dimple structure of sheet by analysis of Dynaform and LS-Dyna.

• Tribology and Lubricants
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• v.11 no.2
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• pp.44-55
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• 1995

Frictional characteristics with the change of dynamic parameters, such as stiffness, inertia and damping, in the friction measurement at dry sliding surfaces were experimentally and theoretically investigated throughout the study. Dynamic frictional force and the variation in the normal load were mainly measured at the various conditions of system dynamic parameters with which stiffness in the normal direction, loading mechanisms and test materials were varied. For the normal load, mechanisms using both a dead weight and a pneumatic cylinder were applied, which resulted in change of the inertia and damping of the test rig. Test materials were steel, rosin and PTFE, which have different types of intrinsic frictional characteristics. Test results showed that frictional characteristics under different dynamic parameters could be different even though the operating variables were the same and also they could result in the variation in the normal load, which could consequently affect the wear mechanism.

• Proceedings of the KIEE Conference
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• 2011.07a
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• pp.1428-1429
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• 2011

This paper variation of stranded cable conductor with CIP(Cold Isostatic Press) technology. Conductor as cable material takes majority costs. Thus many experiments have been done on conductor compaction. The core technology is to maintain the resistance of circular stranded conductor after compaction process, while reducing the weight of conductor diameter, but by increasing filling factor. Testing by varying the compaction ratio using 300SQ conductor, conductor after CIP process shows lower resistance rather than conductor before CIP process.

• Proceedings of the Korea Concrete Institute Conference
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• 2001.11a
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• pp.427-432
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• 2001

In this study, crushed sand is blended with river sand and sea sand, to investigate the quality change of antiwashout underwater concrete with variation of blend ratio of crushed sand(0%, 20%, 40%, 60%, 80%, 100%). To see experiment conclusion, the more blend ratio of crushed sand increases, the more unit weight increases. Because the for that specific gravity of crushed sand is higher comparatively than that of river sand and sea sand. Higher compressive strength is measured following the order of river sand, crushed sand, sea sand regardless of age and casting-curing condition. Except for case of using river sand, blend ratio of 40% is appeared on most compressive strength. So the optimum blend ratio of crushed sand is 40% from the view point of compressive strength.