• Journal of the Korean Society of Marine Environment & Safety
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• v.26 no.6
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• pp.742-750
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• 2020

The flow noise generated by hull appendages is directly related to the performance of the sonar in terms of self-noise and induces a secondary noise source through interaction with the propeller and rudder. Thus, the noise in the near field should be analyzed accurately. However, the acoustic analogy method is an indirect method that is not used to simulate the propagation of an acoustic signal directly; therefore, diffraction, reflection, and scattering characteristics cannot be considered, and near-field analysis is limited. In this study, the propagation process of flow noise in water was directly simulated by using the lattice Boltzmann method. The lattice Boltzmann method could be used to analyze flow noise by simulating the collision and streaming processes of molecules, and it is suitable for noise analysis because of its compressibility, low dissipation rate, and low dispersion rate characteristics. The flow noise source was derived using Reynolds-averaged Navier-Stokes equations for the hull appendages, and the propagation process of the flow noise was directly simulated using the lattice Boltzmann method by applying the developed flow-acoustic boundary conditions. The derived results were compared with Ffowcs Williams-Hawkings results and hydrodynamic pressure results based on the receiver location to verify the usefulness of the lattice Boltzmann method within the near-field range in comparison with other techniques.

• Journal of Environmental Science International
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• v.25 no.4
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• pp.473-481
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• 2016

We examined the effects of ocean acidification (OA) and eutrophication on the physiology of a red alga, Gracilariopsis chorda, using specimens collected at Wando Island, Korea, in July of 2015. The samples were transported to a laboratory and placed on growth media for treatments involving low or high levels of ammonium ($4{\mu}M$ or $60{\mu}M\;NH_4{^+}$) and low or high pH(7.5 or 8.2). The control treatment used filtered seawater (pH 8.2 and $4{\mu}M\;NH_4{^+}$). All experiments were conducted at $20^{\circ}C$ and under a lighting intensity of $80{\mu}mol\;photons\;m^{-2}\;s^{-1}$, with or without an injection of $CO_2$ (pH 7.5). In addition, we calculated rates of respiration under darkness, at a pH of 7.5 and $60{\mu}M\;NH_4{^+}$. Fluctuations in pH as well as the evolution of photosynthetic oxygen and $NH_4{^+}$ uptake rates were monitored for 6 h. The greatest increase in pH levels, from 7.50 to 8.65, occurred in response to $60{\mu}M\;NH_4{^+}$, whereas the largest decrease, from 7.50 to 7.42, was associated with elevated respiration rates. At a pH of 7.5, rates of oxygen evolution were higher (236% saturation) for samples treated with $60{\mu}M\;NH_4{^+}$ than for the control (121% saturation). Ammonium uptake was highest at pH 7.5 and $60{\mu}M\;NH_4{^+}$, with a rate of $0.526{\pm}0.002{\mu}mol\;g^{-1}\;FW\;h^{-1}$, followed in order by the treatments of $pH\;8.2/60{\mu}\;NH_4{^+}$, $pH\;7.5/4{\mu}M\;NH_4{^+}$, and the control ($pH\;8.2/4{\mu}M\;NH_4{^+}$). We speculated that the rates of photosynthesis and $NH_4{^+}$ uptake could be enhanced at a higher ammonium concentration and lower pH because $CO_2$ concentrations were increased through greater photosynthetic activity. Therefore, these findings suggest that the physiology of G. chorda populations can be improved by the interaction of optimized $CO_2$ concentrations and an adequate supply of essential nutrients such as ammonium.

• Korean Journal of Plant Tissue Culture
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• v.27 no.1
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• pp.1-6
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• 2000

This study was carried out to find the effects of plant growth regulators on callus formation, rooting and shooting from cotyledon explant in oriental me]on. Various combinations of 0.1 mg/L auxins (IAA, NAA) and 0.5, 1.0. 1.5, 2.0 mg/L cytokinins (BA, kinetin, zeatin) were treated to the MS basal medium, respectively. Callus was induced mort effectively as 2,437.0 mg (FW)/explant in MS medium supplemented with 0.1 mg/L NAA and 2.0 mg/L BA, but that was non-embryogenic callus as colored yellow white and broke easily. Root was induced most effectively at a frequency of 98.0% in MS medium supplemented with 0.1 mg/L NAA and 0-5 mg/L kinetin. Shoots formed on cut part of vein at a frequency of 98.0% in MS medium supplemented with 0.1 mg/L IAA and 2.0 mg/L BA, that were multiple shoots. in case of its concentration, BA and lower concentration of IAA and NAA (0.01 and 0.05 mg/L). respectively. shooting ratio was not increased. The result of treatment with BA 0-5 mg/L and IAA 0.1 mg/L, callus induced at a week, and shoot start to form multiple shoots about 3 weeks after inoculation. After 2 times subculture as 2 weeks intervals, divided shoots rooted and developed into intact plantlets at 10 weeks and then that grown normally on pots after acclimatization.

• Korean Journal of Organic Agriculture
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• v.20 no.3
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• pp.313-326
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• 2012

The aim of this study was to determine the effect of effective microorganisms (EM) on growth, yield and fruit nutrient contents of two cultivars ('Muhanjilju' and 'Daetong') of hot pepper. The number of injection of EM cultivated are 6 times from the pepper plant seedlings until harvested in both cultivars. Stem girth was highest in the treatment of Lactobacillus plantarum whereas lowest in no EM control. In 'Muhanjilju', the number of branches was highest (79.3) in the treatment of Bacillus subtilis whereas in 'Daetong' was highest (119.0) as treated with Lactobacillus plantarum. Yield of the red hot pepper fruits that sum of two varieties was highest in the treatment of Rhodopseudomonas capsulatas (53.1kg FW per 10a). Regardless of EM treatments, average yield was 8% higher in 'Daetong' than is 'Muhanjilju' (33.8kg vs 31.2kg per 10a). The incidence of antracnose was lowest by the Rhodopseudomonas capsulatas treatment, which led to the highest yield. As for the effect on fruit mineral nutrients, total N and phosphorus concentrations were highest in the treatment of Lactobacillus plantarum and Bacillus subtilis in both varieties, respectively. The highest content of total carotenoids was obtained from the treatment of Lactobacillus plantarum in both varieties.

• Korean Journal of Environmental Agriculture
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• v.20 no.3
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• pp.175-179
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• 2001

To find out the effect of cadmium(Cd) on growth of major vegetables in Korea, phytotoxicity and absorption of Cd were investigated with chinese cabbage, radish, and lettuce grown in upland soils of different Cd concentrations. Cadmium phytotoxicity was shown by growth retardation and leaf chlorosis in chinese cabbage and lettuce at the early growing stage. The threshold concentrations of growth damage resulting from the significant reduction (5%) of growth and yield of chinese cabbage and lettuce were $50{\sim}100$ and $10{\sim}25$ mg/kg soil, respectively. However, there was no significant reduction of radish yield under Cd treatment of 100 mg/kg soil. As Cd concentrations in soils increased, the contents of Cd in products were significantly increased, basically. The contents of Cd in edible part of chinese cabbage, radish, and lettuce grown at the 5 mg/kg Cd treated soils were 0.13, 0.18, and 3.37 mg/kg FW, respectively. Total absorbed Cd in the vegetables tended to occur in the following order, chinese cabbage > radish > lettuce above 25 mg/kg Cd treated soils whereas lettuce absorbed more Cd than chinese cabbage and radish below 10 mg/kg Cd concentration.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.13 no.1
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• pp.105-113
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• 2000

Seismic behavior of 3-dimensional setback structures showing abrupt reductions of the floor size within the structure height and the effect of in-plane deformations of floor slabs on the seismic behavior of those structures are investigated. To find out general seismic behavior of 3-dimensional setback structures two parameters, level of setback(L/sub s/) and degree of setback(R/sub s/) are used. Analysis results obtained from forty eight setback structures show that a sudden change in story shear near setback level is occurred for irregular setback structures. The effect of in-plane deformation of floor slabs on the seismic behavior of setback structures is greatly influenced by the arrangement of lateral load resisting elements and it is more pronounced for frame-shear wall system showing large difference in stiffness among the lateral load resisting elements. The in-plane deformation of floor slabs results in reduced base shear, especially for FW-type structures with L/sub s/=1.0. Also, it brings about reduced story shear for the lateral load resisting element with shear wall and increase in story shear lot the lateral load resisting element without shear wall. The in-plane deformation of floor slabs at the base portion and/or tower portion due to difference in stiffness among the lateral load resisting elements brings about increment of floor displacements at all floor level.

• The Journal of the Korea Contents Association
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• v.12 no.6
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• pp.353-360
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• 2012

The purpose of this study was to determine whether there are relationships between radiologic parameters for osteoporosis by the proximal femur radiograhps and bone mineral density, as assessed by Dual Energy X-ray Absorptiometry(DEXA). Proximal femur anterior-posterior projection were taken from 112 individuals who undergoing DEXA. Radiographic parameters including canal-to-calcar ratio(CCR) and cortical thickness indices(CTI) were measured and compared with bone mineral density($g/cm^2$), T-score. The intramedullary femoral canal width(FW) and calcar width(CW) at osteoporosis group was significantly larger than that of control group. The CCR were correlated negatively with bone mineral density($g/cm^2$)(r=-0.340, p<0.01), and the CTI were correlated positively(r=0.624). The diagnostic accuracy of CCR for osteoporosis was 63.4%, and kappa value was 0.271. And the accuracy of CTI was 67.0%, and kappa value was the level of fair agreement(${\kappa}$=0.258). The proximal femur with large CCR and small CTI had lower T-scores. When evaluating proximal femur anterior-posterior radiographs, those patients with the thinnest femur diaphyseal cortices should be referred for further osteoporosis investigation.

• Journal of Korea Foresty Energy
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• v.22 no.2
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• pp.44-53
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• 2003

This study was conducted to develop new fertilizers which can be applied to various environmental conditions. Fertilizers with different levels of nitrogen, phosphorus and potassium, and different types and amount of combined fertilizers were used on 1-1 seedlings of Pinus densiflora, Larix leptolepis, Quercus acutissima, and Betula platyphylla var. japonica. Biomass, specific leaf area (SLA) and chlorophyll content of foliage were measured. Biomass of foliage, shoot, and root showed no differences among fertilization treatments. Biomass of double treatments of solid-combination fertilizer and UF combination fertilizer increased whereas those of triple treatments decreased. SLA ($\textrm{cm}^2$/g) of P. densiflora fo. the 6:4:1 treatment and L. leptolepis for the 3:4:1 treatment showed the highest with 59.2 and 110.0, respectively, but those of Q. arutissima and B. platyphylla var. japonica for the control showed the higher than other treatments with 207.5 and 202.0, respectively. Chlorophyll contents (mg/g) in the foliage of P. densiflora and L. leptolepis fertilized with the 6:4:1 treatment were 0.222 and 0.127, respectively, and these contents were higher than those of the 3:4:1 treatment with 0.211 and 0.082, respectively. These results suggested that the increased nitrogen fertilization had an effort on increase of chlorophyll contents.

• Journal of dental hygiene science
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• v.10 no.6
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• pp.445-450
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• 2010

The aim of this study was to evaluate the effect according to the fiber type and combination on the reinforcement of heat-polymerized denture base resin. The heat-polymerized resin(Vertex RS, Dentimax, Netherlands) was used in this study. Glass fiber(GL; ER 270FW, Hankuk Fiber Glass, Korea), polyaromatic polyamide fiber(PA; aramid; Kevlar-49, Dupont, U.S.A.) and ultra high molecular weight polyethylene fiber(PE, polyethylene; P.E, Dong Yang Rope, Korea) were used to reinforce the denture base resin specimens. The final size of test specimen was $64mm{\times}10mm{\times}3.3mm$. The specimens of each group were stored in distilled water at $37^{\circ}C$ for 50 hours before measurement. The flexural strength and flexural modulus were measured by an universal testing machine(Z020, Zwick, Germany) at a crosshead speed of 5 mm/min in a three-point bending mode. In this study, all fibers showed reinforcing effects on denture base resin(p<0.05). In terms of flexural strength and flexural modulus, glass fiber 5.3 vol.% showed most effective reinforcing effect on heat polymerized denture base resin. For flexural modulus, PA/GL was the highest in denture base resin specimen for hybrid FRC using two combination (p<0.05). Glass fiber 5.3 vol.% and PA/GL are considered to be applied effectively in reinforcing the heat polymerized denture base resin.

• Korean Journal of Food Science and Technology
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• v.48 no.1
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• pp.86-91
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• 2016

Oxidative stress caused by reactive oxygen species is ascribed to many neurodegenerative diseases like Alzheimer's disease. Phenolic antioxidants can reduce the oxidative stress. In this study, ripe fruits of Opuntia ficus-indica var. saboten (OFS) were extracted using 80% (v/v) aqueous ethanol. Total phenolic and flavonoid contents of the OFS fruits (100 g) were 409.9 mg gallic acid equivalents and 72.2 mg catechin equivalents, respectively. The OFS fruits had antioxidant capacity at 381.2, 298.2, and 3,219.9 mg vitamin C equivalents/100 g in ABTS, DPPH, and ORAC assays, respectively. The OFS fruits showed protective effects on PC-12 cells against oxidative stress in a dose-dependent manner, partly due to decrease of intracellular oxidative stress. Furthermore, the OFS fruits inhibited both acetylcholinesterase and butyrylcholinesterase. Consequently, these results suggest that the OFS fruits might be served as a source of functional materials to reduce oxidative stress in neuronal cells and to inhibit cholinesterases.