• Journal of the Korean Society of Physical Medicine
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• v.15 no.3
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• pp.1-9
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• 2020

PURPOSE: This study examined the effects of muscle fatigue on proprioception in the type of taekwondo training, causing injury to taekwondo athletes. METHODS: The subjects were divided into Taekwondo Kyorugi athletes (n = 14) and Taekwondo Poomsae athletes (n = 14). After inducing muscle fatigue to the subjects, the joint position sense (JPS) and the force reproduction sense (FRS) were measured before and immediately after the induction of muscle fatigue. RESULTS: Studies have shown no significant impact on the JPS and FRS caused by muscle fatigue induced by Poomsae and Kyorugi (p > .05). The JPS, however, showed a significant difference before and after Kyorugi (p < .05). The FRS showed significant differences before and after Poomsae (p < .05). Through this study, the injuries to taekwondo athletes appear to be influenced by the joint position and force reproduction. Moreover, the injury appears to affect the joint position sense in Kyorugi athletes and the force reproduction sense in Poomsae athletes. CONCLUSION: The results will contribute to injury prevention and athlete protection. In addition, the information can be used as basic data for the development of sports injuries prevention and rehabilitation programs for Taekwondo athletes. Research is needed on the customized management of sports methods and self-care to prevent sports damage, considering the athletic characteristics of the taekwondo athletes in the future.

• Journal of Biosystems Engineering
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• v.40 no.3
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• pp.261-270
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• 2015

Purpose: Cold storage is the most popular method used to preserve highly perishable foods such as beef and fish. However, at refrigeration temperatures, the shelf life of these foods is limited, and spoilage leads to massive food waste. Moreover, freezing significantly affects the food's properties. Ice crystallization and growth during freezing can cause irreversible textural damage to foods through volumetric expansion, moisture migration induced by osmotic pressure gradients, and concentration of solutes,which can lead to protein denaturation. Methods: Although freezing can preserve perishable foods for months, these disruptive changes decrease the consumer's perception of the food's quality. Therefore, the development and testing of new and improved cold storage technologies is a worthwhile pursuit. Results: The process of maintaining a food product in an unfrozen state below its equilibrium freezing temperature is known as supercooling. As supercooling has been shown to offer a considerable improvement over refrigeration for extending a perishable product's shelf life, implementation of supercooling in households and commercial refrigeration units would help diminish food waste. Conclusions: A commercially viable supercooling unit for all perishable food items is currently being developed and fabricated. Buildup of this technology will provide a meaningful improvement in the cold storage of perishable foods, and will have a significant impact on the refrigeration market as a whole.

• Reproductive and Developmental Biology
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• v.28 no.4
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• pp.257-260
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• 2004

Efficiency of somatic cell nuclear transfer was investigated in mice. First, oocyte activation was induced by SrCl₂, and the rate of development was compared with embryos from normal fertilization. Although more than one half of SrCl₂-treated oocytes developed to blastocysts (146/262, 55.7%), the rate of blastocyst formation was significantly lower than normal fertilization controls (59/79, 74.6%). Second, enucleation of oocytes was performed using Polscope that enables non-invasive visualization of metaphase spindles. Such approach could not only avoid damage of oocytes during an exposure to UV light often employed in conventional enucleation procedures, but could also assure the removal of nuclei from all oocytes operated because of monitoring the location of spindles during an entire process of enucleation. Morphologically normal blastocysts were obtained from the transfer of cumulus cell nuclei into enucleated oocytes. However, the rate of development into the blastocyst stage was still low (4/93, 4.3%). This reflects that the nuclear transfer procedure used in this study was not sufficiently optimized, and other factors may also impact greatly the efficiency of nuclear transfer. Including an induction of oocyte activation and method of enucleation tested in this study, a lot more elements are remained to be optimized to improve the efficiency of somatic cell nuclear transfer in mice.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.15 no.8
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• pp.4790-4795
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• 2014

The machine tool is used widely to manufacture and trial manufactured goods in many machinery industries. Blast-induced ground vibration may have an environmental impact, such as damage to the adjacent structures and facilities. This study examined the influence of blast vibration on the accuracy of machine tools. The blast vibration and vibration of machine tools was measured to evaluate the influence of blast vibration on machine tools. Based on the evaluation of the vibration limit of machine tools, the vibration criteria for machine tools in this study were SLIGHTLY ROUGH~ROUGH. By repeated blast vibration, machine tools are more likely show reduced accuracy.

• Advances in concrete construction
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• v.8 no.1
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• pp.55-64
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• 2019

Chloride corrosion has become the main factor of reducing the service life of reinforced concrete structures. The object of this paper is to propose a theoretical model that predicts the service life of chloride-corrosive concrete under fatigue load. In the process of modeling, the concrete is divided into two parts, microcrack and matrix. Taking the variation of mcirocrack area caused by fatigue load into account, an equation of chloride diffusion coefficient under fatigue load is established, and then the predictive model is developed based on Fick's second law. This model has an analytic solution and is reasonable in comparison to previous studies. Finally, some factors (chloride diffusion coefficient, surface chloride concentration and fatigue parameter) are analyzed to further investigate this model. The results indicate: the time to pit-to-crack transition and time to crack growth should not be neglected when predicting service life of concrete in strong corrosive condition; the type of fatigue loads also has a great impact on lifetime of concrete. In generally, this model is convenient to predict service life of chloride-corrosive concrete with different water to cement ratio, under different corrosive condition and under different types of fatigue load.

• Geomechanics and Engineering
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• v.25 no.2
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• pp.111-121
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• 2021

Large deformation and rapid pressure propagation take place inside the rock mass under the dynamic loads caused by the explosives, on quarry faces in order to extract aggregate material. The complexity of the science of rock blasting is due to a number of factors that affect the phenomenon. However, blasting engineering computations could be facilitated by innovative software algorithms in order to determine the results of the violent explosion, since field experiments are particularly difficult to be conducted. The present research focuses on the design of a Finite Element Analysis (FEA) code, for investigating in detail the behavior of limestone under the blasting effect of Ammonium Nitrate & Fuel Oil (ANFO). Specifically, the manuscript presents the FEA models and the relevant transient analysis results, simulating the blasting process for three types of limestone, ranging from poor to very good quality. The Finite Element code was developed by applying the Jones-Wilkins-Lee (JWL) equation of state to describe the thermodynamic state of ANFO and the pressure dependent Drucker-Prager failure criterion to define the limestone plasticity behavior, under blasting induced, high rate stress. A progressive damage model was also used in order to define the stiffness degradation and destruction of the material. This paper performs a comparative analysis and quantifies the phenomena regarding pressure, stress distribution and energy balance, for three types of limestone. The ultimate goal of this research is to provide an answer for a number of scientific questions, considering various phenomena taking place during the explosion event, using advanced computational tools.

• Journal of Korea Trade
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• v.25 no.6
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• pp.34-56
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• 2021

Purpose - This study presents strategies to overcome the COVID-19-induced crisis in Korea's meetings, incentives, conferences, and exhibitions (MICE) industry. It aims to quantitatively identify the environmental factors affecting the industry and their degree of influence, and derive optimal countermeasures. Design/methodology - The study applied the SWOT-AHP-TOWS framework. An AHP analysis was first performed within the SWOT frame, and then a TOWS analysis was conducted using the results of the SWOT-AHP analysis. In the AHP analysis, the number of pairwise comparison questions was limited to four for each SWOT factor to increase the consistency of responses by reducing the burden on respondents. Findings - The plunge in demand (threats factor) has had an overwhelming impact on the MICE industry, more than any other environmental factor. To overcome the crisis, the ST alternative that takes advantage of dynamic pop culture to minimize the business damage caused by the plunge in demand was the top priority measure. Based on the results, this study presents suggestions for overcoming the crisis in the MICE industry. First, the industry should develop profitable business models to supplement scarce financial resources by exploiting Korea's success with quarantine management. Second, the government must provide emergency relief funds or bailout support to protect MICE facilities and employees. Originality/value - Unlike previous work on the MICE industry, this study utilized the SWOT-AHPTOWS framework to derive quick research results in an abnormal situation. This approach can be expanded to other countries with different industrial environments and situations. Additionally, when applying this method to MICE sub-sectors, countermeasures should be tailored to each field.

• Journal of the Korean Geotechnical Society
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• v.23 no.3
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• pp.111-121
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• 2007

The paper presents a reliability-based method that can capture the impact of uncertainty of seismic loadings. The proposed method incorporates probabilistic concepts into the classical limit equilibrium and the Newmark-type deformation techniques. The risk of damage is then computed by Monte Carlo simulation. Random process and RMS hazard method are introduced to produce seismic motions and also to use them in the seismic slope analyses. The geotechnical variability and sampling errors are also considered. The results of reliability analyses indicate that in a highly seismically active region, characterization of earthquake hazard is the more critical factor, and characterization of soil properties has a relatively small effect on the computed risk of slope failure and excessive slope deformations. The results can be applicable to both circular and non-circular slip surface failure modes.

• Journal of Microbiology and Biotechnology
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• v.34 no.7
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• pp.1395-1400
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• 2024

The antimicrobial activity of the natural compounds from plant and food have well discovered since the interest on the beneficial effect of the natural compounds was risen. Quercetin, a flavonoid derived from vegetables, including onions, red leaf lettuces and cherries has been studied for diverse biological characteristics as anti-cancer and anti-microbial activities. The aim of current study is to investigate the specific antibacterial modes of action of quercetin against Escherichia coli. Quercetin decreased the E. coli cell viability and induced the severe damages (oxidative stress, DNA fragmentation) leading to cell death. Reactive oxygen species (ROS) generation was observed during the process, which we confirmed that oxidative stress was the key action of antibacterial activity of quercetin exerting its influence potently. Based on the results of Annexin V and Caspace FITC-VAD-FMK assay, the oxidative damage in E. coli has led to the bacterial apoptosis-like death in E. coli. To sum up, the contribution of ROS generation exerts crucial impact in antibacterial activity of quercetin.

• Journal of Ocean Engineering and Technology
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• v.36 no.6
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• pp.380-389
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• 2022

In the Haeundae area of Busan, South Korea, damage has continued to occur recently from building wind from caused by dense skyscrapers. Five wind observation stations were installed near LCT residential towers in Haeundae to analyze the effect of building winds during typhoon Omais. The impact of building wind was analyzed through relative and absolute evaluations. At an intersection located southeast of LCT (L-2), the strongest wind speed was measured during the monitoring. The maximum average wind speed for one minute was observed to be 38.93 m/s, which is about three times stronger than at an ocean observation buoy (12.7 m/s) at the same time. It is expected that 3 to 4 times stronger wind can be induced under certain conditions compared to the surrounding areas due to the building wind effect. In a Beaufort wind scale analysis, the wind speed at an ocean observatory was mostly distributed at Beaufort number 4, and the maximum was 8. At L-2, more than 50% of the wind speed exceeded Beaufort number 4, and numbers up to 12 were observed. However, since actual measurement has a limitation in analyzing the entire range, cross-validation with computational fluid dynamics simulation data is required to understand the characteristics of building winds.