• Korean Journal of Agricultural and Forest Meteorology
• /
• v.25 no.3
• /
• pp.218-225
• /
• 2023

An agrivoltaic system (AVS) is a combined system that generates power through photovoltaic panels (PVPs) installed above a field where a crop is cultivated. Although soil moisture is an important limiting factor for open-field crop production, particularly during spring season in Korea, it is not well considered in the utilization of AVS. Indeed, the application of water-energy-food nexus on the AVS should be necessary. In this study, the changes of soil moisture and temperature under the AVS was investigated in fallow paddy field during spring season. The AVS that has partial shading condition by PV panels was decreased soil temperature and increased soil moisture compared to open-field. Furthermore, the maximum of the change in soil moisture to the change in soil temperature had a negative correlation both on open-field and AVS under wet condition. It represents that the micro-climate under the AVS is in energy-limited condition. The open-field of relatively high soil temperature was in water-limited condition. The different behavior of soil moisture on the AVS should be considered for the sustainable agricultural system as related to water-energy-food nexus.

• Journal of Industrial Convergence
• /
• v.21 no.9
• /
• pp.33-39
• /
• 2023

Nano-sized materials can be coated on various substrates, and since this material is transparent and conductive, it can be used as a transparent electrode for electronic devices or an electrode for power supply. In this study, CNT and Ag nanowires were repeatedly coated using the silk screen technique, and samples formed up to 5 times were fabricated, and their optical and electrical properties were measured and analyzed. It was confirmed that marks were formed on the surface of the silkscreen-coated sample according to the coating direction, and the trend of transmittance and surface resistance according to the number of times of coating was investigated. As the number of coatings increased, transmittance and surface resistance tended to decrease. In particular, in the case of transmittance, the range of change was large in the samples coated 2 and 5 times. These changes were confirmed by the Ag nanowire coating. In addition, starting from 700 nm, the previous wavelength region increased according to the wavelength, while the above showed a tendency to decrease. The surface resistance was lowered from 9Ω/cm² when coating once to 0.856Ω/cm² when coating five times. It was found that the resistance value was affected by Ag similarly to the permeability. In the future, it is necessary to realize a desired transparent electrode through Ag concentration and coating of Ag nanowires with other methods and fusion with highly transparent CNT to apply to electronic devices.

• Journal of the Korean Crystal Growth and Crystal Technology
• /
• v.33 no.6
• /
• pp.288-293
• /
• 2023

To optimize the process parameters of laser powder bed fusion process to fabricate the high density STS316L alloy, the effect of laser power, scanning speed and hatching distance on the relative density was studied. Tensile properties of additively manufactured STS316L alloy using optimized parameters was also evaluated according to the build direction. As a result of additive manufacturing process under the energy density of 55.6 J/mm³, 83.3 J/mm³ and 111.1 J/mm³, high density STS316L specimens was suitably fabricated when the energy density, power and scan speed were 83.3 J/mm³, 225 W and 1000 mm/s, respectively. The yield strength, ultimate tensile strength, and elongation of STS316L specimens in direction perpendicular to the build direction, show the most competitive values. Anisotropic shape of the pores and the lack of fusion defects probably caused strain localization which result in deterioration of tensile properties.

• Journal of Aerospace System Engineering
• /
• v.18 no.1
• /
• pp.1-10
• /
• 2024

In a previous study, a structure of a superplastic yoke consisting of a thin FR4 layer laminated with viscoelastic tape on both sides of a shape memory alloy (SMA) was proposed to reduce residual vibration generated by a deployable solar panel during high motion of a satellite. Damping properties of viscoelastic tapes will change with temperature, which can directly affect vibration reduction performance of the yoke. To check damping performance of the yoke at different temperatures, free damping tests were performed under various temperature conditions to identify the temperature range where the damping performance was maximized. Based on above temperature test results, this paper predicts temperature of the yoke through orbital thermal analysis so that the yoke can have effective damping performance even if it is exposed to an orbital thermal environment. In addition, the thermal design method was described so that the yoke could have optimal vibration reduction performance.

• Journal of Internet Computing and Services
• /
• v.25 no.1
• /
• pp.157-166
• /
• 2024

The Army TIGER System, which is being deployed to implement a future combat system, is expected to bring innovative changes to the army's combat methods and comabt execution capability such as mobility, networking and intelligence. To this end, the Army will introduce various systems using drones, robots, unmanned vehicles, AI(Artificial Intelligence), etc. and utilize them in combat. The use of various unmanned vehicles and AI is expected to result in the introduction of equipment with new technologies into the army and an increase in various types of transmitted information, i.e. data. However, currently in the military, there is an acceleration in research and combat experimentations on warfigthing options using Army TIGER forces system for specific functions. On the other hand, the current reality is that research on cyber threats measures targeting information systems related to the increasing number of unmanned systems, data production, and transmission from unmanned systems, as well as the establishment of cloud centers and AI command and control center driven by the new force systems, is not being pursued. Accordingly this paper analyzes the structure and characteristics of the Army TIGER force integration system and makes suggestions for necessity of building, available cyber defense solutions and Army TIGER integrated cyber protections system that can respond to cyber threats in the future.

• The Journal of the Acoustical Society of Korea
• /
• v.28 no.4
• /
• pp.318-327
• /
• 2009

In this paper, we propose a 3-D geometric localization method for near-field broadband source in shallow water environments. According to the waveguide invariant theory, slope of the interference pattern which is seen in a sensor spectrogram directly proportional to a range of the source. The relative ratio of the range between source and sensors was estimated by matching of two interference patterns in spectrogram. Then this ratio is applied to the Apollonius's circle which shows the locus of a source whose range ratio from two sensors is constant. Two Apollonius's circles from three sensors make the intersection point that means the horizontal range and the azimuth angle of the source. And this intersection point is constant with source depth. Therefore the source depth can be estimated using 3-D hyperboloid equation whose range difference from two sensors is constant. To evaluate a performance of the proposed localization algorithm, simulation is performed using acoustic propagation program and analysis of localization error is demonstrated. From simulation results, error estimate for range and depth is described within 50 m and 15 m respectively.

• Korean Chemical Engineering Research
• /
• v.62 no.1
• /
• pp.80-86
• /
• 2024

This study was conducted to evaluate the potential of rape stalk (RAS) as a raw material for the production of solid bio-fuels. RAS was immersed in an aqueous solution with acetic acid concentration of 1 percent, The content of reducing sugars separated from the RAS was analyzed. Glucose showed the highest content followed by xylose, galactose, arabinose and mannose. The immersed and non-immersed RAS were used for producing pellets with a pilot-scaled flat-die pellet mill. Bulk density and calorific values of the pellets improved with the use of the immersed RAS and the addition of wood particles. The values exceeded the minimum requirements for the A-grade of non-woody pellets (≧600 kg/m³ & ≧ 14.5 MJ/kg) designated by the ISO. Ash content of the pellets reduced with the immersion of RAS and the value satisfied the A-grade level (≦6.0%) of the ISO standard. The durability of the immersed RAS-based pellets was much higher than that of non-immersed IRS-based pellets, and the values were increased with the addition of wood particles. However, the durability did not meet the acceptance level for the B-grade of non-woody pellets (≧96.0%) designated by the ISO. These results suggested that the addition of binders in the production of non-woody pellets using an RAS immersed in acetic acid-based aqueous solution is required for the commercialization of the pellets.

• Industry Promotion Research
• /
• v.9 no.2
• /
• pp.69-75
• /
• 2024

Korea has entered the ranks of advanced countries in terms of economic size and technological competitiveness. However, its industrial accident fatality rate remains among the lowest in OECD countries, and recent incidents such as various building collapses have resulted in numerous deaths of workers or citizens, reminiscent of accidents in developing countries. According to the 2022 Industrial Accident Status Analysis by the Ministry of Employment and Labor, out of the 874 fatalities in work-related accidents in 2022 across all industries, 402 were in the construction industry, accounting for approximately 46% of all fatalities. In particular, the construction industry's fatality rate stands at 1.61, significantly higher than the overall industry fatality rate of 0.43, indicating its severity. Construction ranks highest in terms of fatality rates, with mining at 12.18 and fishing at 1.80. When categorizing construction projects into private and public, private projects show significantly higher figures in terms of contracts, contract amounts, accident numbers, and fatalities compared to public projects. However, unlike public agencies, many private clients lack adequate safety and health activities and lack established safety and health systems. This study aims to raise awareness among private clients about the need to establish safety and health systems and enhance safety and health activities, and to discuss the direction of future development of advanced safety and health practices among private clients.

• Information Systems Review
• /
• v.19 no.1
• /
• pp.75-100
• /
• 2017

Today, firms are constantly transforming and innovating to survive under the rapidly changing business environment. The introduction of cloud computing services has become popular throughout society as a whole and is expected to result in many changes and developments not only in firms and but also in the public sector subject to innovation. The purpose of this study is to investigate the effect of the characteristics of cloud computing services on the perceived expected performance according to innovativeness based on innovation diffusion theory. The results of the analysis of the data collected from this research are as follows. The convenience and understanding of individuals' work as well as the benefits of cloud computing services to them depend on the innovative trend of cloud computing services. Further, the expectations for personal benefit and those for organizational benefit of cloud computing services are different from each other. Leading firms in the global market have been actively engaged in the utilization of cloud computing services in the public sector as well as in private firms. In consideration of the importance of cloud computing services, using cloud computing services as the target of innovation diffusion research is important. The results of the study are expected to contribute to developing future research models for the diffusion of new technologies, such as big data, digital convergence, and Internet of Things.

• Korean Journal of Clinical Laboratory Science
• /
• v.55 no.4
• /
• pp.314-323
• /
• 2023

This study assessed the desired wage guidelines for medical technologists (MTs), mainly primary care providers and those in secondary medical institutions, in 16 cities and provinces in Korea. A survey of 1,327 MTs was conducted using a structured Google questionnaire from August 1, 2022, to September 30, 2022. The wage levels differed according to gender, age, education, career, region, and employment status. There were differences in wage levels according to gender and region with less than one year of career, and the wage gap was relatively larger for woman than man. An awareness of wage compensation appropriate for work performance, and technology value compensation were low at 2.01, 2.23, and 2.30, respectively. This study suggests that primary and secondary medical institutions should provide reasonable wages compensation for MTs' work in order to create an environment where MTs can receive stable jobs and work. Moreover, the Korean Association of Medical Technologists should establish a cooperative system so that the starting wage of MTs in primary and secondary medical institutions can receive the desired wage of 34 million won.