• International Journal of Naval Architecture and Ocean Engineering
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• v.10 no.5
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• pp.545-565
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• 2018

A numerical code is developed based on potential flow theory to investigate nonlinear sloshing in rectangular Liquefied Natural Gas (LNG) tanks under forced excitation. Using this code, internal free-surface elevation and sloshing loads on liquid tanks can be obtained both in time domain and frequency domain. In the mathematical model, acceleration potential is solved in the calculation of pressure on tanks and the artificial damping model is adopted to account for energy dissipation during sloshing. The Boundary Element Method (BEM) is used to solve boundary value problems of both velocity potential and acceleration potential. Numerical calculation results are compared with published results to determine the efficiency and accuracy of the numerical code. Sloshing properties in partially filled rectangular and membrane tank under translational and rotational excitations are investigated. It is found that sloshing under horizontal and rotational excitations share similar properties. The first resonant mode and excitation frequency are the dominant response frequencies. Resonant sloshing will be excited when vertical excitation lies in the instability region. For liquid tank under rotational excitation, sloshing responses including amplitude and phase are sensitive to the location of the center of rotation. Moreover, experimental tests were conducted to analyze viscous effects on sloshing and to validate the feasibility of artificial damping models. The results show that the artificial damping model with modifying wall boundary conditions has better applicability in simulating sloshing under different fill levels and excitations.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.20 no.1
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• pp.67-74
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• 2009

In this paper, we investigate the performance limitations of SubCarrier Multiplexed(SCM) WDM systems using optical Double-Side Band(DSB) modulated 16 QAM signals. The Bit-Error Rate(BER) performance is evaluated under various optical transmission links including the effects of the dispersion and fiber nonlinearities such as SPM(Self-Phase Modulation) and XPM(cross-phase modulation). After simulation of SCM-WDM systems, the dominant factors determining the entire system performance are appeared to be the nonlinearity of MZ(Mach-Zehnder) modulator and the SCM channel spacing. The BER performance of subcarrier channels in the higher frequencies was degraded with the large dispersion effect only, however, the performance was improved a little with a combined effect of fiber dispersion and nonlinear effect when the hish fiber launching power was applied.

• The Journal of Engineering Geology
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• v.28 no.3
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• pp.349-365
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• 2018

The strain and acoustic emission (AE) signals of Pocheon granite were measured during uniaxial compression tests to investigate microcrack formation and damage. Crack closure, initiation, and damage stresses of each sample were determined through an analysis of the crack volumetric strain and stiffness. The samples experienced four damage stages according to stress levels: stage 1 = crack closure stage; stage 2 = elastic stage; stage 3 = crack initiation stage; stage 4 = crack damage stage. At least 75% of all AE signals occurred in stages 3 and 4, and different AE parameters were detected in the four stress stages. Rise time, count, energy, and duration clearly showed a tendency to gradually increase with the damage stress stage. In particular, the rise time, energy, and duration increased by at least 95% in stage 4 as compared with stage 1. However, the maximum amplitude showed a smaller increase, and the average frequency decreased slightly at higher stages. These results indicate that as the degree of rock damage increases, the crack size grows larger. The crack types corresponding to the AE signals were determined using the relationship between RA (Rise time / Amplitude) values and average frequencies. Tension cracking was dominant in all stress stages. Shear cracking was rare in stages 1 and 2, but increased in stages 3 and 4. These results are consistent with previous studies that reported cracking begins after samples have already been damaged. Our study shows that the state of rock damage can be investigated solely through an analysis of AE parameters when rocks are under compressive stress. As such, this methodology is suitable for understanding and monitoring the stress state of bedrock.

• Geophysics and Geophysical Exploration
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• v.16 no.4
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• pp.203-210
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• 2013

To look into site characteristics of the Hwacheon borehole seismic station, we analyzed property of earthquake and microtremor recorded on surface and borehole seismometers. Acoording to analysis result of microtremor, the surface-to-borehole energy ratio was approximately 15 times greater during the daytime than during the nighttime, and the surface-to-borehole ratios of spectral amplitudes as frequency increases. For earthquake data, amplitude spectra and dominant frequency were computed using surface and borehole data. As a result, small earthquakes with short distance recorded on surface seismometer peaked at 8 Hz, 46 Hz. This result corresponds to resonance frequencies (7.4 Hz, 46 Hz) calculated by H/V spectral ratio. We confirmed amplification effect by site characteristics of overburden. Background noise level was approximately 20,000 times smaller at borehole seismic station than surface seismic station. These results provide strong evidence for the superior recording of earthquakes using borehole seismometers instead of surface seismometers.

• Composites Research
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• v.14 no.3
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• pp.1-9
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• 2001

A new non-destructive fatigue prediction model of the composite laminates is developed. The natural frequencies of fatigue-damaged laminates under extensional loading are related to the fatigue life of the laminates by establishing the equivalent flexural stiffness reduction as a function of the elastic properties of sublaminates. The flexural stiffness is derived by relating the 90-ply elastic modulus reduction, and using the laminate plate theory to the degraded elastic modulus and the intact elastic modulus of other laminates. The natural frequency reduction model, in which the dominant fatigue mode can be identified from the sensitivity scale factors of sublaminate elastic properties, provides natural frequency vs. fatigue cycle curves for the composite laminates. Vibration tests were also conducted on $[{90}_2/0_2]_s$ carbon/epoxy laminates to verify the natural frequency reduction model. Correlations between the predictions of the model and experimental results are good.

• Asian Pacific Journal of Cancer Prevention
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• v.14 no.7
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• pp.4083-4087
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• 2013

We conducted an exploratory investigation of whether variation in six common SNPs of xeroderma pigmentosum complementation group F (XPF) is associated with risk of glioma in a Chinese population. Six single nucleotide polymorphisms (SNPs) were genotyped in 207 glioma cases and 236 cancer-free controls by a 384-well plate format on the Sequenom MassARRAY platform (Sequenom, San Diego, USA). The rs1800067 G and rs2276466 G allele frequencies were significantly higher in the glioma group than controls. Individuals with the rs1800067 GG genotype were at greater risk of glioma when compared with the A/A genotype in the codominant model, with an OR (95% CI) of 2.63 (1.04-7.25). The rs2276466 polymorphism was significantly associated with moderate increased risk of glioma in codominant and dominant models, with ORs (95% CI) of 1.90 (1.05-3.44) and 1.55 (1.07-2.47), respectively. The combination genotype of rs1800067 G and rs2276466 G alleles was associated with a reduced risk of glioma (OR=0.44, 95% CI=0.19-0.98). These findings indicate that genetic variants of the XPF gene have critical functions in the development of glioma.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.47 no.2
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• pp.35-42
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• 2010

In this study, crosstalk between dominant interconnect pairs in an A/D converter circuit is analyzed in frequency domain and effects of termination conditions on crosstalk are described, based on the practical circuit conditions. An A/D converter circuit is a mixed circuit where both clean and noisy signals coexist such that the circuit probably suffers from distortion by crosstalk. An analog input signal and the reference voltage signal, which dominate the overall conversion performance of the A/D converter circuit, are ready to be distorted by crosstalk and include specific termination conditions, such as non-matching and capacitive termination, respectively. Thus, this study presents the model of crosstalk considering impedance mismatch at both ends and analyzes effects of the practical termination conditions in the analog input and the reference voltage interconnects on crosstalk. A typical circuit configuration of the two interconnects is described and crosstalk including near-end and far-end termination impedances is modeled. Effects of the near-end impedance mismatch in the analog input interconnect and the far-end capacitive termination in the reference voltage interconnect are estimated in the frequency domain by using the model of crosstalk and experiments are performed to confirm the estimated results. Microstrip lines are used as interconnects, involving the increase of loss in high frequencies.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.18 no.1
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• pp.25-35
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• 2015

Pennisetum aloperculoides is a key revegetation species mixed with other plants species and used for revegetating cut-slopes. The purpose of this research is to identify the effects of mixed seeding of revegetation plants on cut-slope revegetation with respect to the quantity of Pennisetum aloperculoides seeds. The coverage ratio and appearance frequency of Pennisetum aloperculoides, and other revegetation species were measured to assess the cut-slope revegetation. We divided Pennisetum treatments into four groups with different Pennisetum seed quantities of $0g/m^2$, $5g/m^2$, $10g/m^2$, and $15g/m^2$. For each treatment group, we mixed identical quantities of seeds from herbaceous flowers (bird's-boot trefoil, aster, chrysanthemums, golden coreopsis and china pink), cool-season turfgrasses, and woody plants (korean lespedeza, indigo and silk tree). The increase in the quantity of the Pennisetum seeds resulted in the higher coverage ratio for Pennisetum, but in the lower coverage ratio for herbaceous flowers, cool-season turfgrasses, and woody plants. We observed a short-term succession process in which the dominant species shifted in the following order: the initial species Pennisetum, herbaceous flowers, and then lastly woody plants. In case of the appearance frequency, we also observed the higher appearance frequency for Pennisetum and the lower appearance frequency for the other plants due to the increase in the quantity of Pennisetum seeds. Pennisetum, bird's-foot trefoil and china pink showed the tendency to decrease the appearance frequency from one month after seeding while cool-season turfgrasses became extinct due to summer drought. In the woody plants, the appearance frequencies of korean lespedeza and indigo were high due to the decrease in quantity of Pennisetum seeds. The silk trees were damaged from winter frost and none emerged at all in 2013 (the following year after the seeding). Korean lespedeza and indigo appeared to have the short-term rapid dominance over other treated revegetation plants.

• Asian-Australasian Journal of Animal Sciences
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• v.23 no.10
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• pp.1268-1275
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• 2010

Post-weaning diarrhoea (PWD) and oedema disease (ED) caused by E. coli F18 always result in economic losses to pig producers, and no effective methods of controlling PWD and ED are presently available. FUT1 has been identified as a candidate gene controlling the expression of E. coli F18 receptor. This study examined the correlation between F18ab and F18ac adhesion phenotypes and the polymorphism at position M307 of the FUT1 gene in three pig breeds (231 Large White, 107 Landrace and 109 Songliao Black). The results showed: i) Both the susceptible genotypes (GG and GA) and the adhesion phenotypes (adhesive or weekly adhesive) were dominant in all three breeds with frequencies over 95%. ii) Three adhesion patterns of the two F18 variants F18ab and F18ac, i.e., ($ab^+$, $ac^+$), ($ab^+$, $ac^-$) and ($ab^-$, $ac^-$), were found in all three breeds, and there was no significant difference in the distribution of adhesion phenotypes of the two variants (separately or jointly) among the three breeds (p>0.05). iii) The FUT1 M307 genotypes were completely associated with the F18ab adhesion phenotypes and very strongly associated with the F18ac adhesion phenotypes. All individuals of genotype AA were non-adhesive to both F18ab and F18ac. All individuals of genotype GG or GA were adhesive to F18ab, whereas 11% of them were non-adhesive to F18ac. These results suggest that the polymorphism at FUT1 M307 can be used for marker-assisted selection of PWD and ED resistant pigs.

• Asian Pacific Journal of Cancer Prevention
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• v.13 no.5
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• pp.2325-2328
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• 2012

Background: Cyclin D1 (CCND1) is critical in the transition of the cell cycle from G1 to S phases and unbalanced cell cycle regulation is a hallmark of carcinogenesis. A number of studies conducted to assess the association between CCND1 G870A polymorphism and susceptibility to lung cancer have yielded inconsistent and inconclusive results. In the present study, the possible association above was assessed by a meta-analysis. Methods: Eligible articles were identified for the period up to November 2011. Pooled odds ratios (OR) with 95% confidence intervals (95%CI) were appropriately derived from fixed effects or random-effects models. Sensitivity analysis excluding studies whose genotype frequencies in controls significantly deviated from the Hardy-Weinberg equilibrium (HWE) was performed. Results: Ten case-control studies with a total of 10,548 subjects were eligible. At the overall analysis the CCND1 870A allele appeared to be associated with elevated lung cancer risk (for allele model, pooled OR = 1.24, 95% CI: 1.08-1.44, P = 0.004; for homozygous model, pooled OR = 1.45, 95% CI: 1.14-1.84, P = 0.003; for recessive model, pooled OR = 1.29, 95% CI: 1.06-1.58, P = 0.013; for dominant model, pooled OR = 1.33, 95% CI: 1.08-1.65, P = 0.009). Subgroup analyses by ethnicity and sensitivity analysis further pointed to associations, particularly in Asians. Conclusion: This meta-analysis suggests that the A allele of CCND1 G870A polymorphism confers additional lung cancer risk.