• Journal of Ecology and Environment
• /
• v.46 no.1
• /
• pp.31-40
• /
• 2022

Background: Plant vegetation appears in heterogeneous and patchy forms in arid and semi-arid regions. In these regions, underneath the plant patches and the empty spaces between them are covered by biological soil crusts (moss, lichen, cyanobacteria, and fungi). Biological soil crusts lead to the formation and development of fertile islands in between vegetation patches via nitrogen and carbon fixation and the permeation of runoff water and nutrients in the soil. Results: The present study has investigated the association of biological soil crusts, the development of fertile islands, and the formation of plant patches in part of the Takht-e Soltan protected area, located in Khorasan Razavi Province, Iran. Three sites were randomly selected as the working units and differentiated based on their geomorphological characteristics to the alluvial fan, hillslope, and fluvial terrace landforms. Two-step systematic random sampling was conducted along a 100-meter transect using a 5 m² plot at a 0-5 cm depth in three repetitions. Fifteen samplings were carried out at each site with a total of 45 samples taken. The results showed that the difference in altitude has a significant relationship with species diversity and decreases with decreasing altitude. Results have revealed that the moisture content of the site, with biocrust has had a considerable increase compared to the other sites, helping to form vegetation patterns and fertile islands. Conclusions: The findings indicated that biological crusts had impacted the allocation of soil parameters. They affect the formation of plant patches by increasing the soil's organic carbon, nitrogen, moisture and nutrient content provide a suitable space for plant growth by increasing the soil fertility in the inter-patch space.

• Computers and Concrete
• /
• v.31 no.6
• /
• pp.537-543
• /
• 2023

To study the seismic behavior of recycled aggregate concrete filled circular steel tube (RACFCST) frames, the seismic behavior experiment of RACFCST frame was carried out to measure the hysteresis curve, skeleton curve and other seismic behavior indexes. Moreover, based on the experimental study, a feasible numerical analysis model was established to analyze the finite element parameters of 8 RACFCST frame specimens, and the influence of different variation parameters on the seismic behavior index for RACFCST frame was revealed. The results showed that the skeleton curve of specimens under different axial compression ratios were divided into three stages: elastic stage, elastic-plastic stage and descending stage, and the descending stage was relatively stable, indicating that the specimen had stronger deformation capacity in the descending stage. With the increase of axial compression ratio, the peak bearing capacity of all specimens reduced gradually, and the reduction was less than 5%. With the decrease of beam-column linear stiffness ratio, the peak bearing capacity decreased gradually. With the decrease of yield bending moment ratio of beam-column, the peak bearing capacity decreased gradually, and the decreasing rate of peak bearing capacity gradually accelerated. In addition, compared with the axial compression ratio, the beam-column linear stiffness ratio and the yield bending moment ratio of beam-column had a more significant influence on the peak bearing capacity of RACFCST frame.

• International conference on construction engineering and project management
• /
• 2022.06a
• /
• pp.443-449
• /
• 2022

With climate change and the global population growth, the frequency and scope of wildfires are constantly increasing, which threatened people's lives and property. For example, according to California Department of Forestry and Fire Protection, in 2020, a total of 9,917 incidents related to wildfires were reported in California, with an estimated burned area of 4,257,863 acres, resulting in 33 fatalities and 10,488 structures damaged or destroyed. At the same time, the ongoing development of technology provides new tools to simulate and analyze the spread of wildfires. How to use new technology to reduce the losses caused by wildfire is an important research topic. A potentially feasible strategy is to simulate and analyze the spread of wildfires through computing technology to explore the impact of different factors (such as weather, terrain, etc.) on the spread of wildfires, figure out how to take preemptive/responsive measures to minimize potential losses caused by wildfires, and as a result achieve better management support of wildfires. In preparation for pursuing these goals, the authors used a powerful computing framework, Spark, developed by the Commonwealth Scientific and Industrial Research Organization (CSIRO), to study the effects of different weather factors (wind speed, wind direction, air temperature, and relative humidity) on the spread of wildfires. The test results showed that wind is a key factor in determining the spread of wildfires. A stable weather condition (stable wind and air conditions) is beneficial to limit the spread of wildfires. Joint consideration of weather factors and environmental obstacles can help limit the threat of wildfires.

• Earthquakes and Structures
• /
• v.26 no.1
• /
• pp.31-48
• /
• 2024

In order to get a better understanding of seismic performance of exterior beam-column joint, reciprocating loading tests with variable loading speeds or axial forces were carried out. The main findings indicate that only few cracks exist on the surface of the joint core area, while the plastic hinge region at the beam end is seriously damaged. The damage of the specimen is more serious with the increase of the upper limit of variable axial force. The deflection ductility coefficient of specimen decreases to various degrees after the upper limit of variable axial force increases. In addition, the higher the loading speed is, the lower the deflection ductility coefficient of the specimen is. The stiffness of the specimen decreases as the upper limit of variable axial force or the loading speed increase. Compared to the influence of variable axial force, the influence of the loading speed on the stiffness degradation of the specimen is more obvious. The cumulative energy dissipation and the equivalent viscous damping coefficient of specimen decrease with the increase of loading speed. The influence of variable axial force on the energy dissipation of specimen varies under different loading speeds. Based on the truss model, the biaxial stress criterion, the Rankine criterion, the Kent-Scott-Park model, the equivalent theorem of shearing stress, the softened strut-and-tie model, the controlled slip theory and the proposed equations, a calculation method for the shear capacity is proposed with satisfactory prediction results.

• Asian-Australasian Journal of Animal Sciences
• /
• v.33 no.2
• /
• pp.203-211
• /
• 2020

Objective: Staphylococcus aureus (S. aureus) is one of the major microorganisms responsible for subclinical mastitis in dairy cattle. The present study was designed with the aim to explore the DNA methylation patterns using the Fluorescence-labeled methylation-sensitive amplified polymorphism (F-MSAP) techniques in a S. aureus-infected mouse model. Methods: A total of 12 out-bred Institute of Cancer Research female mice ranging from 12 to 13 weeks-old were selected to construct a mastitis model. F-MSAP analysis was carried out to detect fluctuations of DNA methylation between control group and S. aureus mastitis group. Results: Visible changes were observed in white cell counts in milk, percentage of granulocytes, percentage of lymphocytes, CD⁴⁺/CD⁸⁺ ratio (CD⁴⁺/CD⁸⁺), and histopathology of mice pre- and post-challenge with S. aureus. These findings showed the suitability of the S. aureus-infected mouse model. A total of 369 fragments was amplified from udder tissue samples from the two groups (S. aureus-infected mastitis group and control group) using eight pairs of selective primers. Results indicated that the methylation level of mastitis mouse group was higher than that in the control group. In addition, NCK-associated protein 5 (Nckap5) and transposon MTD were identified to be differentially methylated through secondary polymerase chain reaction and sequencing in the mastitis group. These observations might play an important role in the development of S. aureus mastitis. Conclusion: Collectively, our study suggests that the methylation modification in Nckap5 and transposon MTD might be considered as epigenetic markers in resistance to S. aureus-infected mastitis and provided a new insight into S. aureus mastitis research in dairy industry and public health.

• Tunnel and Underground Space
• /
• v.16 no.6 s.65
• /
• pp.526-535
• /
• 2006

An experimental study was carried out on a reduced scale tunnel model to grasp the behavioral feature of fire-induced smoke in the long tunnels. Based on Froude modeling, the 1/50 scaled tunnel model (20 m long) was constructed by acrylic tubes and paraffin gas was released inside the tunnel to simulate the 20 MW fire-induced smoke. me test results show, that after approximately 2 minutes of fire generation, was descended from the tunnel ceiling through the decrease of buoyancy, then it was symmetrically propagated about 90 meters for 4 minutes before jet fans were operated. The smoke was effectively controlled when the jet fans were operated and an air stream velocity was getting closed to reach a critical velocity (the minimum air velocity that requires to suppress the smoke spreading against the longitudinal ventilation flow during the tunnel fire situations). It was also found out that a range of smoke was spreaded about 3 meters from the origin of fire but the range was not propagated to the escape direction anymore. The early stage of the In operation, however, showed that the smoke was hardly controlled. It means that the operation of emergency ventilation system has many dangerous factors such as an intercepting breathing zone.

• Journal of the Society of Naval Architects of Korea
• /
• v.34 no.4
• /
• pp.31-41
• /
• 1997

This paper describes a potential-based panel method formulated for the prediction of the steady performance of a waterjet propulsor. The method employs normal dipoles and sources distributed on the solid surfaces such as the impeller/stator blades, hub and duct, and normal dipoles in the shed wakes trailing the impeller and stator to represent the potential flow around the waterjet propulsor. To define a closed boundary surface, the inlet and outlet open boundary surfaces are introduced where the sources and dipoles are distributed. The kinematic boundary condition on the solid boundary surface is satisfied by requiring that the normal component of the total velocity should vanish. On the inlet surface, the total inflow flux into the duct is specified, and on the outlet surface the conservation of mass principle is applied to evaluate the source strength. The solid surfaces are discretized into a set of quadrilateral panel elements and the strengths of sources and dipoles are assumed constant at each panel. Applying this approximation to the boundary conditions leads to a set of simultaneous equations. Systematic numerical tests show that the present numerical method is fast and stable. In order to validate the present method, sample computations are carried out first for the case of a conventional axial flow fan which has a similar geometry as the waterjet propulsor, and then for the case of a waterjet propulsor on which experiments are carried out at KRISO(Korea Research Institute of Ships and Ocean Engineering).

• Journal of KIISE:Information Networking
• /
• v.29 no.6
• /
• pp.696-705
• /
• 2002

This paper presents a new copy network for multicast ATM switches. Many studies have been carried out up to date since the proposition of Lee's copy network. However, the overflows and cell conflicts within the switch have still been raised a problem in argument. In order to reduce those problems, we proposed a 3-dimensional multicast switching architecture which has shared buffers in this paper. The proposed architecture can reduce the overflows and cell conflicts through multiple paths and output ports even in the high load environments. Also, we proposed a cell splitting algorithm which handles the cell in the case of large fan-out, and a copy network to increase throughput by expanding the Lee's Broadcast Banyan Network(BBN). Cell copy uses the Boolean interval splitting algorithm and the multicast pattern of the cells according to the self-routing characteristics of the network. In the proposed copy network, we improve the problems such as overflow, cell splitting of large fanout, cell conflicts, etc., which were still existed in the Lee's network. The results of performance evaluation by computer simulation show that the proposed scheme has better throughput, cell loss rate and cell delay than the conventional method.

• Food Science and Preservation
• /
• v.11 no.2
• /
• pp.263-268
• /
• 2004

Two field cooling tests were conducted to evaluate the cooling characteristic of paddy with a prototype grain cooler. The first test was carried out during summer season in a steel bin with 180.3ton of paddy at Sunchon. And the second test was carried out during harvesting season in a steel bin with 272.2ton of paddy at Ulsan. At the first test, initial paddy temperature of 23.6$^{\circ}C$ was dropped to 14$^{\circ}C$, and initial moisture content of 19.9% was dropped to 19.3% after 52.5 hours of cooling. At the second test, initial paddy temperature of 16.1$^{\circ}C$ dropped to 5.5$^{\circ}C$ after 78.0 hours of cooling. And, at the first test, the average air flow rates of chilled air leaving the grain cooler and penetrating the grain layer were 77.5 ㎥/min and 42.5 ㎥/min, respectively. To prevent leakage of chilled air from plenum chamber of steel bin, which was about 45% of the average air flow rates of chilled air leaving the grain cooler, a proper method was required. The average total power consumption at the first test during summer was 22.1 ㎾ with control of fan damper. At the second test, it was 17.4 ㎾ due to controlling the capacity of compressor with unloading solenoid valve and changing the flow rates of hot refrigerant gas flowing into evaporator and reheater from compressor, resulting in 27% reduction of energy consumption.

• Cross-Cultural Studies
• /
• v.40
• /
• pp.213-238
• /
• 2015

This article attempts to correct errors in five words related to Shiji (The Grand Scribe's Records) Liezhuan (A Series of Biographies), which are presented in the Great Chinese-Korean Dictionary. The author analyses the problems with meaning interpretations of three words and additional meaning interpretations of two words. The main points of the study are presented in the following. First, in relation to the error correction in meaning interpretation, this study finds out that the explanations of "jiayu," "jiaochi," and "guancai" in the Great Chinese-Korean Dictionary are incorrect. Most of the cases include plausible interpretations of the words that are likely to cause readers to be confused with the meanings. Each of the words should be interpreted as "lend${\rightarrow}$give," "arrangement${\rightarrow}$new decoration, ornamentation, or embellishment after removing old one," and "accept something carefully or accept something after inspection${\rightarrow}$look over carefully or search for something." Second, as for the supplementary correction, this study points out that the explanations of "xiaoshi" and "shennian" are not sufficient. The following meanings for each word should be added, including "display skills" and " be trapped inside one's own mind." Furthermore, when comparing with the different translation versions by scholars at home and abroad, we can come to a following conclusion. The interpretations made by Zheng, Fan-Zhen are the most accurate for the "jiayu" item. With respect to the "jiaochi" item, the interpretations given by Piao, Yi- Feng; Wang, Li-Qi; Yang, Zhong-Xian; and Hao, Zhi-Da are relatively appropriate. The "guancai" item is adequately interpreted by Piao, Yi-Feng and Wang, Li-Qi. In the meaning interpretation of the "xiaoshi," Jin, Yuan- Zhong gave correct explanations. In addition, it is considered that Wang, Zhong provided the most ideal translations for the item "shennian."