In this study, based on the daily maximum wind speed and maximum instantaneous wind speed data recorded at 61 observation points operated by the Korea Meteorological Administration from 1993 to 2018, ...the self-organizing map clustering method was used to classify regions with similar characteristics of strong wind and gust wind occurrence and intensity. Characteristics of these regions were analyzed by averaging 30 variables related to wind for each cluster. As a result, 13 homogeneous regions of strong wind and gust wind in Korea were identified, which were clearly divided into regions of high and low strong wind frequency of occurrences. In most regions, the average daily maximum wind speed and maximum instantaneous wind speed were high in spring and winter. However, the average daily maximum wind speed and maximum instantaneous wind speed exceeding the criteria of strong wind (14 m s−1) and gust wind (20 m s−1) in this study were high in summer and autumn. Among the four clusters with high occurrence of strong wind and gust wind, one was classified as a specific region with high occurrence in summer and autumn. This results are likely to be beneficial to support regional customized special weather reports and disaster prevention.
The value management (VM) approach often faces many barriers when applied in the Vietnamese construction industry, as well as in many other developing countries. Most of the related past works ...identify an insufficient number of factors that hinder the application of VM. This study identified 18 factors hindering the application of VM in the construction industry. To gather views from industrial practitioners with many years of experience in construction projects, this study administered questionnaire surveys. The findings revealed that the four greatest obstacles to the application of VM were the lack of VM experts, the lack of knowledge about VM, the lack of local VM guidelines, as well as technical norms and standards, and the lack of investments, support policies and human resources to conduct VM in construction companies. Additionally, the factor analysis method was applied to investigate the correlation effects of the hindrance factors, which resulted in four core components representing the hindrance factors, namely, lack of qualified personnel to implement VM, inherent difficulties with VM workshops, lack of awareness of VM, and lack of VM application documents. The study contributes to the body of knowledge relating to the application of VM in the construction industry. The findings can be generalised to many developing countries, as they face similar problems in terms of promoting the application of VM in the construction industry.
Strong winds are one of the several factors contributing to natural disasters. Although in recent years, the intensity and frequency of strong winds has decreased, different areas are differently ...affected by such winds; these winds still have the potential to cause adverse impacts on life and property. In Korea, strong winds are also responsible for the incidence of increased number of accidents and forest fires. Therefore, in this study, relationship between wind speed and damage was analyzed, and the threshold value of damage-causing wind speed was estimated. We first analyzed the relationship between wind speed and damage occurrences based on the daily maximum wind speed and daily maximum instantaneous wind speed data, and data on damage related to strong winds. Second, we examined the validity regarding the regional segmentation of the Korean criteria of special weather report for strong winds using the critical success index and cumulative percentile distributions to estimate the damage-causing threshold value for each region. We found that damage resulting from very strong wind speeds in Korea had not occurred in recent times. In addition, considerable damage had occurred because of low-speed wind compared to the current criteria for high wind advisory. However, the incidence of damage was higher when wind speed was stronger than the current criteria for high wind advisory. Based on threshold estimation, the study areas were categorized into areas with high threshold values (coastal, mountainous, and island), and those with low threshold values (inland areas). A notable difference was observed between the threshold values of the two categories of areas. This necessitated the regional segmentation of the criteria of special weather report on strong winds.
The full genome sequence of a Middle East respiratory syndrome coronavirus (MERS-CoV) was identified from cultured and isolated in Vero cells. The viral genome sequence has high similarity to 53 ...human MERS-CoVs, ranging from 99.5% to 99.8% at the nucleotide level.
•Magnetoceramic composed by a-SiCN and α-Fe was manufactured using synthesized phenyl-silsesquiazane (PSSQZ) as precursor.•High C content of PSSQZ induces only α-Fe crystalline phase growth without ...other Fe crystalline phases.•The a-SiCN/α-Fe showed improved magnetic properties due to pure α-Fe crystalline phase.
Display omitted
Magnetoceramics composed of pure α-Fe crystals grown in an amorphous silicon carbonitride matrix were prepared using phenyl-silsesquiazane (PSSQZ) and iron oxide (Fe3O4) as precursors. Magnetoceramics with commercial polysilazane were also synthesized for comparison. The PSSQZ induced growth of only α-Fe crystals in the magnetoceramics because of the high C content of the phenyl group of PSSQZ and the ability of the precursor to control the Si content; moreover, Fe silicide was not formed. In addition, the effect of the chemical composition of the precursor on the crystal phase growth was confirmed via ab initio thermodynamic calculations. The growth of pure α-Fe crystals resulted in improvements in magnetic saturation from 10.62 to 27.82 emu/g. This study showed that the microstructure of the magnetoceramics could be controlled according to precursor composition, resulting in an improved magnetic property.
In the present work, K
2Ti
2O
5, K
2Ti
4O
9 and K
2Ti
6O
13 are synthesized by solid state method. Their structures and morphologies are characterized by X-ray diffraction, Raman spectra and scanning ...electron microscopy. The binding energies of K, Ti and O in potassium titanates were then evaluated by X-ray photoelectron spectroscopy and compared with those in K/TiO
2. Finally the corresponding K ion exchange properties are investigated by synthesizing NO oxidation catalysts with Co(NO
3)
2 precursor. It is found that the binding energy of K in K
2Ti
2O
5 is much higher than those in K
2Ti
4O
9 and K
2Ti
6O
13, and because of which, it shows quite different catalytic performances. Compared with other potassium titanates, the K in K
2Ti
2O
5 is much easier to be exchanged out.
With the increasing use of virtual reality (VR) devices, interest in reducing their negative effects, such as VR sickness, is also increasing. This study used electroencephalography (EEG) to ...investigate participants’ VR sickness recovery time after watching a VR video. We tested 40 participants in advance using a motion sickness susceptibility questionnaire (MSSQ). We classified the participants into two groups (sensitive group/non-sensitive group) depending on their MSSQ scores. We used a simulator sickness questionnaire (SSQ) and EEG to evaluate VR sickness. The SSQ score increased significantly after watching the VR sickness-inducing video (VR video) in both groups (p < 0.001). The recovery time based on the SSQ was 11.3 ± 6.6 min for the sensitive group and 9.1 ± 5.2 min for the non-sensitive group. The difference in recovery time between the two groups was not significant (p > 0.05). EEG results showed that recovery time took an average of 11.5 ± 7.1 min in both groups. The EEG data showed that the delta wave increased significantly across all brain areas (p < 0.01). There was no statistical difference between groups in recovering VR sickness depending on individual characteristics. However, we confirmed that subjective and objective VR recovery required at least 11.5 min. This finding can inform recommendations regarding the VR sickness recovery times.
•This study investigated recovery time to relieve VR sickness symptoms.•Delta increased after watching the VR video compared to before watching the VR video.•Delta power reduced with time during the recovery period.•The SSQ found that participants needed 10.2 ± 6.0 min to recover from VR sickness.•The EEG also showed that the delta power returned to baseline at 11.5 ± 7.1 min.
Shape memory polymer (SMP) is one of smart polymers which exhibit shape memory effect upon external stimuli such as heat, moisture, electricity etc. To overcome low mechanical properties of SMP, a ...woven carbon fiber-reinforced shape memory polymer composite (SMPC) has been proposed. However, the prediction of the mechanical behavior of woven carbon fiber-reinforced SMPC is not routine due to anisotropy and multidimensional deformation during bending or unfolding. In this study, a 3D constitutive model of woven carbon fiber reinforced SMPC was developed based on phenomenological three elements in parallel; rubbery and glassy phases and anisotropic fiber part. To treat the anisotropic behavior of woven fabric reinforcement such as high stiffness with slight nonlinearity in the warp and weft directions and nonlinear shear behavior, an anisotropic hyperplastic constitutive model was used that decompose total strain energy into warp and weft stretching and fabric shearing energies. Finally, 3D constitutive equation was obtained by summing the stresses resulting from rubbery and glassy phases and fiber part considering interface effect between matrix and fiber. The developed equation was implemented into COMSOL software. Finally, shape memory bending and anisotropic behavior of woven carbon fiber-reinforced SMPCs was simulated.
The complete genome sequence of the wild-type genotype 2B rubella virus RVi/Busan.KOR/10.152B, isolated from a patient in South Korea, was determined. The availability of this sequence will help in ...understanding the circulation of endemic rubella viruses, as well as their genetic diversity.
PDF
