• International Journal of Highway Engineering
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• v.19 no.6
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• pp.129-137
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• 2017

PURPOSES : The purpose of this study is to develop bridge deck concrete materials based on ordinary Portland cement concrete, and to evaluate the applicability of the developed materials through material properties tests. METHODS : For field implementation, raw material (cement, fine aggregate, and coarse aggregate) properties, fresh concrete properties (slump and air content), strength (compressive, flexural and bond strength) gain, and durability (freeze-thaw resistance, scaling resistance, and rapid chloride penetrating resistance) performance were evaluated in the laboratory. RESULTS : For the selected binder content of $410kg/m^3$, W/B = 0.42, and S/a = 0.48, the following material performance results were obtained. Considering the capacity of the deck finisher, a minimum slump of 150 mm was required. At least 6 % of air content was obtained to resist freeze-thaw damage. In terms of strength, 51.28 MPa of compressive strength, 7.41 MPa of flexural strength, and 2.56 MPa of bond strength at 28 days after construction were obtained. A total of 94.9 % of the relative dynamic modulus of elasticity after 300 cycles of freeze-thaw resistance testing and $0.0056kg/m^2$ of weight loss in a scaling resistance test were measured. However, in a chloride ion penetration resistance test, the result of 3,356 Coulomb, which exceeds the threshold value of the standard specification (1000 Coulomb at 56 days) was observed. CONCLUSIONS : Instead of using high-performance modified bridge deck materials such as latex or silica fume, we developed an optimum mix design based on ordinary Portland cement concrete. A test construction was carried out at ramp bridge B (bridge length = 111 m) in Gim Jai City. Immediately after the concrete was poured, the curing compound was applied, and then wet mat curing was applied for 28 days. Considering the fact that cracks did not occur during the monitoring period, the applicability of the developed material is considered to be high.

• Journal of Ginseng Research
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• v.4 no.1
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• pp.104-120
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• 1980

The effects of temperature on transpiration, chlorophyll content, frequency and aperture of stomata, and leaf temperature of Panax ginseng were reviewed. Temperature changes of soil and air under spade roof were also reviewed. Growth responses of responses of ginseng plant at various temperature were assessed in relation to suseptibillity of ginseng plants. Reasonable management of ginseng fields was suggested based on the response of ginseng to various temperatures. Stomata frequency may be increased under high temperature during leaf$.$growing stage. Stomata aperture increased by high temperature but the increase of both frequency and aperture appears not enough for transpiration to overcome high temperature encountered during summer in most fields. Serial high temperature disorder, i.e high leaf temperature, chlorophyll loss, inhibition of photosynthesis, increased respiration and wilting might be alleviated by high humidity and abundant water supply to leaf. High air temperature which limits light transmission rate inside the shade roof, induces high soil temperature(optimum soil temperature 16∼18$^{\circ}C$) and both(especially the latter) are the principal factors to increase alternaria blight, anthracnose, early leaf fall, root rot and high missing rate of plant resulting in poor yield. High temperature disorder was lessen by abundant soil water(optimum 17∼21%) and could be decreased by lowering the content of availability of phosphorus and nitrogen in soil consequently resulting in less activity of microorganisms. Repeated plowing of fields during preparation seems to be effective for sterilization of pathogenic microoganisms by high soil temperature only on surface of soils. Low temperature damage appeared at thowing of soils and emergence stage of ginseng but reports were limited. Most limiting factor of yield appeared as physiological disorder and high pathogen activity due to high temperature during summer(about three months).

• Safety and Health at Work
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• v.9 no.3
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• pp.239-248
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• 2018

Background: Workers may be exposed to various types of occupational hazards at the same time, potentially increasing the risk of adverse health outcomes. The aim of this review was to analyze the effects of multiple occupational exposures and coexposures to chemical, biomechanical, and physical hazards on adverse health outcomes among agricultural workers. Methods: Articles published in English between 1990 and 2015 were identified using five popular databases and two complementary sources. The quality of the included publications was assessed using the methodology developed by the Effective Public Health Practice Project assessment tool for quantitative studies. Results: Fifteen articles were included in the review. Multiple chemical exposures were significantly associated with an increased risk of respiratory diseases, cancer, and DNA and cytogenetic damage. Multiple physical exposures seemed to increase the risk of hearing loss, whereas coexposures to physical and biomechanical hazards were associated with an increased risk of musculoskeletal disorders among agricultural workers. Conclusion: Few studies have explored the impact of multiple occupational exposures on the health of agricultural workers. A very limited number of studies have investigated the effect of coexposures among biomechanical, physical, and chemical hazards on occupational health, which indicates a need for further research in this area.

• Journal of Korea Trade
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• v.24 no.8
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• pp.19-38
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• 2020

Purpose - The Korean government has been promoting the New Southern Policy (NSP) prior to the onset of the COVID-19 pandemic, which damage global value chain (GVC). The purpose of this paper is to emphasize that the NSP should be developed to provide tangible support in corporate GVC adjustment, away from diplomatic activities in order to offset GVC losses due to COVID-19 and expand export capabilities. Design/methodology - Two research methodologies are combined for this paper: A computational general equilibrium (CGE) model is used to estimate the impacts of the COVID-19 pandemic and NSP on Korea's exports, and the decomposition methodology (Wang, Wei and Zhu, 2013) to evaluate the stability of GVC. The conventional CGE model was modified to obtain an estimate for decomposition. The research methodology adopted in this study was attempted for the first time, and it can be widely used in future GVC research. Findings - Results found the effects of COVID-19 reduced Korea's total exports by 27% and GVC by more than 30%. In particular, VA in Korea's exports to the NSP region was found to have a huge impact in heavy industries and textiles, and its exports to Vietnam seemed to suffer the largest loss in GVC among ASEAN countries. If the NSP is implemented properly, it appears that it could offset much of the negative impacts of COVID-19, implying the importance of the effectiveness of the NSP. Originality/value - Many papers have assessed the NSP descriptively, and the GVC has been a topic for many publications. However, the impact of COVID-19 on Korea's GVC with the NSP countries has not been quantitatively studied. This paper emphasizes that the NSP should be pursued based on the results of quantitative analysis. In addition, the research methodology of this paper can be used for other GVC research with relevant modifications.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.22 no.11
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• pp.1544-1553
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• 2018

Recently internal information leakage in industries is severely increasing in spite of industry security policy. Thus, it is essential to prepare an information leakage prevention measure by industries. Most of the leaks result from the insiders, not from external attacks. In this paper, a real-time internal information leakage prevention system via both storage and network is implemented in order to protect confidential file leakage. In addition, a Hadoop-based user behavior analysis and statistics system is designed and implemented for storing and analyzing information log data in industries. The proposed system stores a large volume of data in HDFS and improves data processing capability using RHive, consequently helps the administrator recognize and prepare the confidential file leak trials. The implemented audit system would be contributed to reducing the damage caused by leakage of confidential files inside of the industries via both portable data media and networks.

• Journal of the Korean GEO-environmental Society
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• v.20 no.1
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• pp.35-42
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• 2019

Various development works inevitably increase cutting slopes due to land use, and many of trails managed by different authorities are being deteriorated by long-term weathering. Collapse of slopes causes unavoidable damage of property and loss of lives because of its uncertainty and difficulty in predicting its occurrence. In order to overcome the unavoidability, America, Japan, and several European nations analyze the kinetic energy and moving distance when rocks of upper slope move along the inclined plane, via field tests and computerized interpretation of the test results. Also, they are making efforts to develop measures with which the kinetic energy of the rocks moving along the slope is absorbed and fails to reach to specific structures. However, domestic researches just focus on fragmentary prediction of rockfall using existing programs, and there have been few approaches to identify interpretation methods appropriate for domestic cases or determination of parameters. In this context, we in this study defined rockfall types and affecting factors and analyzed effects of parameters using a general-purpose rockfall simulation program to understand principles of rockfall and to estimate effects of various parameters.

• Korean Journal of Agricultural Science
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• v.48 no.1
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• pp.141-149
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• 2021

The cultivation area for domestic cabbage increased by 26.3% from 10,968 ha in 2019 to 13,854 ha in 2020, and among leafy vegetables, the cabbage cultivation area was 62%, and production was 78.9%. Demand for field crop production of cabbage, which has a relatively high-income level compared to rice farming, is increasing, and mechanization of the field operation is urgently needed due to the insufficient development of related farming machinery. In this study, a prototype fabrication and performance test of a tractor-attached cabbage collector was carried out. The transport section was divided into two parts, one for the feeding and transportation and the other for the screening and packaging to selectively collect cabbages in bulk bags or boxes. The length of the primary collecting conveyor was designed to meet the field conditions of the Korean cabbage cultivation standards so that six cultivation rows could be worked simultaneously. Power was controlled by a hydraulic transmission line of the tractor and was easily mounted onto the 3-point hitch links behind the tractor. When the performance was evaluated, the transfer rate, loss rate, damage rate, and work performance were 100, 0, 1.2%, and 1.9 h·10 a^-1. Final improvement and commercialization of the prototype would considerably contribute to the mechanization of harvesting cabbage, the main ingredient of Kimchi.

• Journal of The Korean Society of Integrative Medicine
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• v.11 no.1
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• pp.63-70
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• 2023

Purpose : Excessive alcohol causes damage to skeletal muscles, leading to the development of a specific disease entity called alcoholic myopathy. Chronic inflammation is related as an underlying mechanism for the loss of muscle mass induced by alcohol. Pro-inflammatory cytokines such as TNF-α (tumor necrosis factor-α) and IL-6 (interleukin-6) play a role in this process. The acupuncture point Feng Shi (GB 31) is located on the midline of the lateral aspect of the thigh, above the transverse popliteal crease. This acupoint is used for the treatment of weakness, atrophy, numbness, and post-stroke symptoms of lower limbs. The purpose of this study was to investigate the effect of Feng Shi stimulation on muscle atrophy caused by chronic alcohol administration. Method : Young male Sprague-Dawley rats were randomly divided into three groups of eight each: Normal, Control, and GB31. The rats in the Control and GB31 groups were orally given 25 % ethanol (5 ㎖/kg, body weight) daily for 4 weeks. The Normal group was similarly administered saline. The acupressure at Feng Shi was treated to rats in the GB31 group. After 4 weeks, the body weight, muscle weight and cross-sectional area of gastrocnemius were assessed and the histological changes in gastrocnemius muscle fiber were observed by hematoxylin and eosin staining. Moreover, TNF-α and IL-6 expressions were immunohistochemistrically evaluated. Results : Acupressure stimulation at Feng Shi had a protective effect on the weight reduction of the gastrocnemius muscle caused by alcohol intake, and had an effect of suppressing anatomical change in muscle fiber and decreasing the average cross-sectional area. Also, the immunoreactivities of TNF-α and IL-6 in the GB31 group were decreased. Conclusion : These results suggest that acupressure at Feng Shi has protective effects on chronic alcohol-induced muscle atrophy by inhibiting pre-inflammatory proteins such as TNF-α and IL-6.

• Journal of the Korean GEO-environmental Society
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• v.24 no.2
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• pp.25-30
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• 2023

The high-strength rockfall net developed in this study is to replace the fallout prevention net method using PVC coating net made of core wire thickness 3.2 mm and tensile strength 290-540 MPa class steel wire. General PVC coating net have low performance, and in the event of falling rocks or surface loss, they cannot withstand the load and are torn, which rather adds to the damage. Developed rockfall net was manufactured using steel wires with a core wire thickness of 2.8 to 3.2 mm and a tensile strength of 1,000 to 2,000 MPa. Test method was referred to the international standard Steel wire rope net panels and rolls-Definitions and specifications (ISO 17746:2016), and was conducted in accordance with the provisions of the punching test. Through indoor punching tests, the load-displacement curves of the general PVC coating network and the developed high-strength capture net (1,000 and 2,000 MPa) were compared, and the maximum Pull-out load was analyzed to be improved by 324.47% (2,000 MPa high-strength net).

• Proceedings of the Korean Institute of Building Construction Conference
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• 2023.11a
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• pp.155-156
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• 2023

In the case of steel door frames commonly found in general buildings, there are various assembly methods such as rivets, bolts, and welding, but the welding method is generally used. However, this welding joint method has many problems, such as distortion due to heat and damage due to external shock. In particular, when used as a fire door, problems may occur in the event of a fire due to distortion caused by heat from welding and the weak welded joint area. In the case of rivet or welded joints, when moved after assembly, joint loosening due to external shock may occur. Problems may arise where the bonding strength becomes weak. In addition, with the recent increase in high-rise buildings and larger buildings, when assembly is completed and brought to the site, a place is needed to store it, and in addition, there is a problem in that it has to be transported several times in small quantities to the installation site, which is another problem of time and cost loss. This is coming to the fore. In order to fundamentally solve this problem, we have researched and developed a non-welding door frame that can be assembled on site. We have researched and developed three assembly methods: screw-type, insert-type, and protrusion-type. Non-welded door frames are small in size and easy to package, making them advantageous for domestic and overseas exports.