• Journal of the Korean Wood Science and Technology
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• v.50 no.4
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• pp.283-298
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• 2022

Wood has always been used for various day-to-day applications such as interior or exterior construction materials, and household products. However, it can undergo photodegradation and discoloration by environmental factors including ultraviolet (UV) light, and thus has shortened its service life. Bleaching or delignification of wood surfaces is a suitable solution to stabilize wood against weathering by UV because these techniques can alter or remove the chromophores in lignin, which is a main factor of wood discoloration. To improve the color stability of wood surface according to the lifespan, surface delignification was conducted using peracetic acid (PAA) and hydrogen peroxide (HP) on the woods of Larix kaempferi and Quercus mongolica. After the PAA treatment, L^* increased considerably from 60-70 to 90-95. Furthermore, wood surface color did not change significantly after UV exposure. The color differences (𝜟E^*) between before and after PPA treatment of wood showed the 4.8-12.2 of L. kaempferi, and 1.7-3.7 of Q. mongolica, respectively. The lignin-related peaks in Fourier transform infrared spectroscopy (FT-IR) spectra disappeared with increased duration of PAA treatment. These results confirmed that the lignin component was partially or completely removed after the PAA treatment; the color differences (𝜟E^*) clearly showed that there was a reduction in redness (a^*) and yellowness (b^*), and an increase in lightness (L^*) owing to the removal of lignin. Based on these results, this study demonstrated that the partial removal of lignin from wood surfaces is a fundamental method for resolving photo-degradation.

• Journal of the Korean Society of Safety
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• v.38 no.3
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• pp.10-19
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• 2023

Fall accidents account for the highest accident fatality rate in the construction industry. In addition, wearing and using a safety belt is the most realistic and important preventive measure to reduce fall accidents. Safety belts are protective devices worn by individual workers; they prevent workers from falling and allow for time to rescue the workers. However, the legal standards for safety belts only stipulate the materials, specifications, and strength of parts; there is no provision for an auxiliary rope fixing method to fix the safety belts safely. Due to this reason, workers in industrial sites arbitrarily fix and use the auxiliary rope. Currently, the most used method to fix the auxiliary rope is to tie a knot, which significantly lowers the strength of the material compared to the standard strength. Moreover, many construction sites are located outdoors, so the strength of the materials used in the auxiliary rope is inevitably reduced due to various external environmental conditions. Therefore, to solve this problem, this study was conducted to evaluate the strength of the material of the auxiliary rope for fixing the safety belt and the knot-tying method for the auxiliary rope. In this study, the exposure conditions for the effects of temperature and moisture were set to reflect the characteristics of the construction industry. The results of this study are expected to be used for standards establishment and the safe use of the auxiliary rope for safety belts in actual field applications.

• Journal of Forest and Environmental Science
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• v.26 no.2
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• pp.83-94
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• 2010

Chinese fir (Latin name: Cunninghaimia lanceolata) is one of the major commercial coniferous trees. Most of Chinese fir forests are managed in successive rotation sites, which lead productivity to decline. Autotoxicity is the important reason for soil degradation of Chinese fir plantation, especially, phenolic acids are considered as the major allelopathic toxins which induce autotoxicity in Chinese fir rotation stands. We performed here proteomic approach to investigate the response of proteins in Chinese fir leaves to salicylic acid. The tube plantlets of Chinese fir clone were treated with 120 mg/L salicylic acid for 1, 3 and 5th day. 2-DE, coupled with MALDI-TOF-TOF/MS, was used to separate and identify the responsive proteins. We found 12, 7, and 12 candidate protein spots that were up- or down-regulated by at least 2.5 fold after 1, 3, and 5th day of the stress, respectively. Of these protein spots, 16 spots were identified successfully. According to the putative physiological functions, these proteins were categorized into five classes (1) the proteins involved in protein stability and folding, including 26S proteome, Grp78, Hsp70, Hsp90 and PPIase; (2) the protein involved in photosynthesis and respiration, including OEC 33 kDa subunit, GAPDH; (3) the protein related to cell endurance to acid, F-ATPase; (4) the protein related to cytoskeleton, tubulin; (5) the protein related to protein translation: prolyl-tRNA synthetase. These results give new insights into autotoxic substance stress response in Chinese fir leaves and provide preliminary footprints for further studies on the molecular signal mechanisms induced by the stress.

• Transactions of the Korean hydrogen and new energy society
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• v.33 no.6
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• pp.761-768
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• 2022

In the hope of realizing carbon neutrality, Korea has established the goal of expanding the supply of hydrogen electric vehicles through a roadmap to revitalize the hydrogen economy. A prerequisite for successful supply expansion is securing the safety of hydrogen electric vehicles. Certain parts, such as the hydrogen transport pipe and tank, in hydrogen electric vehicles are exposed to high-pressure hydrogen gas over long periods of time, so the hydrogen enters the grain boundary of material, resulting in a degradation of the parts referred to as hydrogen embrittlement. In addition, since the safety of parts utilizing hydrogen varies depending on the type of material used and its environmental characteristics, the necessity for the enactment of a hydrogen embrittlement regulation has emerged and is still being discussed as a Global Technical Regulation (GTR). In this paper, we analyze a hydrogen compatibility material evaluation method discussed in GTR and present a direction for the development of Korean-type hydrogen compatibility material evaluation methods.

• Applied Chemistry for Engineering
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• v.34 no.3
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• pp.318-325
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• 2023

The detection of antibiotics in treated wastewater is a global concern as it enters water bodies and causes the development of antibiotic resistance genes in humans and marine life. The study specifically aims to explore the potential of ferrate (VI) in eliminating tetracycline (TCL). The degradation of TCL is optimized with parametric studies, viz., the effect of pH and concentration, which provide insights into TCL elimination. The increase in pH (from 7.0 to 10.0) favors the percentage removal of TCL; however, the increase in TCL concentrations from 0.02 to 0.3 mmol/L caused a decrease in percentage TCL removal from 97.4 to 29.1%, respectively, at pH 10.0. The time-dependent elimination of TCL using ferrate (VI) followed pseudosecond-order rate kinetics, and an apparent rate constant (kapp) was found at 1978.8 L² /mol² /min. Coexisting ions, i.e., NaNO₃, Na₂HPO₄, NaCl, and oxalic acid, negligibly affect the oxidation of TCL by ferrate (VI). However, EDTA and glycine significantly inhibited the elimination of TCL using ferrate (VI). The mineralization of TCL using ferrate (VI) was favored at higher pH, and it increased from 18.57 to 32.52% when the solution pH increased from pH 7.0 to 10.0. Additionally, the real water samples containing a relatively high level of inorganic carbon spiked with TCL revealed that ferrate (VI) performance in the removal of TCL was unaffected, which further inferred the potential of ferrate (VI) in real implications.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.30 no.1A
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• pp.15-26
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• 2010

Quasi-static tests were conducted to evaluate structural performance of precast piers prestressed by bonded prestressing steels. Combinations of prestressing bars and normal reinforcing bars, embedded steel tubes and prestressing strands were used as continuous steels crossing the joints of a precast pier. Main design parameters were steel ratio, magnitude of prestress force, and section details. Flexural strength and energy dissipation capacity of precast columns with higher steel ratio showed better performance due to continuous steels after opening of the joints. Precast piers with embedded members showed stable behavior after reaching maximum loads resulting in higher displacement ductility and energy dissipation capacity increased as the introduced prestress increased. Self-centering behavior at early stages and stress increase of confining reinforcements were observed from highly prestressed columns. Combination of prestressing steels and normal reinforcing bars should be used in design to prevent rapid strength degradation after reaching the maximum load.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.26 no.4A
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• pp.587-596
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• 2006

A half portion of Korean railway bridges depends on the type of steel plate girder bridge. Since these bridges have been built in the early stage of Korean economical boom, numerous maintenance effort suffers from aging and progressive degradation issues at present. In accordance with these efforts, this paper would like to address the detailed analyses of thin steel plates with bolts in order to simulate the connection regions of steel plate girder bridge. The fundamental modal analysis, transient dynamic analysis with 3D piezoelectric element in open circuit loop and signal process with aids of TOF(time of flight) and WC(wavelet coefficient) are extensively discussed.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.30 no.2A
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• pp.185-191
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• 2010

Because the concrete crack that is the reason of the serviceability and durability degradation of concrete structure can be arisen from either the stress magnitude and gradient or other structural and material defects, the crack strength of concrete is hard to accurately evaluate. Especially, stress-state in concrete plate components such as rigid pavement and long span slab is biaxial flexure stress, and the flexural strength of those component may be different than the traditional rupture modulus of concrete subjected to uniaxial stress. In this study, an experimental investigation to assess of mechanical behavior under uniaxial and biaxial flexure stress is conducted and the proposed optimum specimen configuration is adopted. From the test, the modulus of rupture under uniaxial and biaxial stress are decreased as the size of aggregate or specimen is larger. And biaxial flexure strength of concrete specimens is varied from 39.5 to 99.2% as compared with that of uniaxial strength, and the biaxial strength of specimen with 20mm aggregate size is only 76% of uniaxial strength.

• International conference on construction engineering and project management
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• 2020.12a
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• pp.455-462
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• 2020

Noise which is unwanted sound is a serious pollutant that can affect human health, as well as the working and living environment if exposed to humans. However, current noise management on the construction project is generally conducted after the noise exceeds the regulation standard, which increases the conflicts with inhabitants near the construction site and threats to the safety and productivity of construction workers. To overcome the limitations of the current noise management methods, the activities of construction equipment which is the main source of construction noise need to be managed throughout the construction period in real-time. Therefore, this paper proposed a framework for automatically detecting noise sources in construction sites in real-time based on convolutional neural networks (CNNs) according to the following four steps: (i) Step 1: Definition of the noise sources; (ii) Step 2: Data preparation; (iii) Step 3: Noise source classification using the audio CNN; and (iv) Step 4: Noise source detection using the visual CNN. The short-time Fourier transform (STFT) and temporal image processing are used to contain temporal features of the audio and visual data. In addition, the AlexNet and You Only Look Once v3 (YOLOv3) algorithms have been adopted to classify and detect the noise sources in real-time. As a result, the proposed framework is expected to immediately find construction activities as current noise sources on the video of the construction site. The proposed framework could be helpful for environmental construction managers to efficiently identify and control the noise by automatically detecting the noise sources among many activities carried out by various types of construction equipment. Thereby, not only conflicts between inhabitants and construction companies caused by construction noise can be prevented, but also the noise-related health risks and productivity degradation for construction workers and inhabitants near the construction site can be minimized.

• Animal Bioscience
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• v.37 no.2_spc
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• pp.370-384
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• 2024

Rumen microbiota play a central role in the digestive process of ruminants. Their remarkable ability to break down complex plant fibers and proteins, converting them into essential organic compounds that provide animals with energy and nutrition. Research on rumen microbiota not only contributes to improving animal production performance and enhancing feed utilization efficiency but also holds the potential to reduce methane emissions and environmental impact. Nevertheless, studies on rumen microbiota face numerous challenges, including complexity, difficulties in cultivation, and obstacles in functional analysis. This review provides an overview of microbial species involved in the degradation of macromolecules, the fermentation processes, and methane production in the rumen, all based on cultivation methods. Additionally, the review introduces the applications, advantages, and limitations of emerging omics technologies such as metagenomics, meta-transcriptomics, metaproteomics, and metabolomics, in investigating the functionality of rumen microbiota. Finally, the article offers a forward-looking perspective on the new horizons and technologies in the field of rumen microbiota functional research. These emerging technologies, with continuous refinement and mutual complementation, have deepened our understanding of rumen microbiota functionality, thereby enabling effective manipulation of the rumen microbial community.