It is essential to select materials with excellent mechanical properties to prevent chemical and mechanical damage to the surfaces of materials used in machines and structures and to extend their lifespan. Co-based stellite alloy, which has wear resistance, heat resistance, and corrosion resistance, is essential for products used in harsh environments. However, due to the problem of enormous costs, research on hard facing, which uses a stellite coating layer only on the contact surface, is urgently required. Currently, high-facing research on Stellite coating layers is focused on powder, and GMAW research using wire is relatively lacking. In this study, welding experiments were performed to form stable weld beads using stellite 6 welding wire, and the correlation between parameters and weld beads was analyzed. A CMT welder was used to minimize the heat effect on the base material.

In this study, changes in the microstructure and mechanical properties of cast and extruded Al-2Li-1Ce alloy materials were investigated as the Mg content was varied. The density decreased to 2.485, 2.46 and 2.435 g/cm3 when the Mg content in the Al-2Li-1Ce alloy was increased to 2, 4 and 6 wt%, respectively. Intermetallic compounds of Al11Ce3 were observed in all alloys, while the β-phase of Al3Mg2 was observed in alloys containing 6 wt% of Mg. In the extruded material, with increasing Mg content the average grain size decreased to 84.8, 71.6 and 36.2 μm, and the fraction of high-angle grain boundaries (greater than 15°) increased to 82.8 %, 88.6 %, and 91.8 %, respectively. This occurred because the increased Mg content promotes dynamic recrystallization during hot extrusion. Tensile test results showed that as the Mg content increased, both the yield strength and tensile strength increased. The yield strength reached 86.1, 107.3, and 186.4 MPa, and the tensile strength reached 215.2, 285, and 360.5 MPa, respectively. However, it is worth noting that the ductility decreased to 27.78 %, 25.65 %, and 20.72 % as the Mg content increased. This reduction in ductility is attributed to the strengthening effect resulting from the increased amount of dissolved Mg, and grain refinement due to dynamic recrystallization.

The importance of urban green space creation is increasingly recognized as the most realistic and efficient approach for fine dust mitigation in urban areas. Particularly considering the characteristics of domestic cities, the application of buffer green spaces along roads can maximize the efficiency of fine dust reduction without the need for separate green space creation. Accordingly, this study analyzed the fine dust mitigation effects based on the types of plantings in the central dividers and roadside trees in Jeonju City, Jeollabuk-do. To do this, we controlled various external variables of urban space and considered the planting arrangement types in the central dividers, carrying out the analysis using a CFD simulation. The simulation results confirmed that the central dividers with plantings demonstrated more effective ultrafine dust reduction than those without. Moreover, the arrangement of roadside trees showed a greater ultrafine dust reduction effect when adopting a multilayered structure compared to a single layer. Based on these findings, we concluded that installing both trees and shrubs simultaneously in the central dividers and along roads was effective for ultrafine dust mitigation. On this basis, we quantified the dust reduction effects of plants in urban street environments and proposed planting guidelines for roadside green spaces to improve air quality.

This study was performed to evaluate the pollutants removal characteristics of two types of RBFs(Riverbank filtration, Riverbed filtration) intake facilities installed in Nakdong River and in Hwang River respectively. The capacity of each RBF is 45,000 ㎥/d for riverbank filtration intake facility and 3,500 ㎥/d for riverbed filtration intake facility. According to data collected in the riverbank filtration site, removal rate of each pollutant was about BOD(Biochemical oxygen demand) 52%, TOC(Total organic carbon) 57%, SS(Suspended solids) 44%, Total coliforms 99% correspondingly. Furthermore, Microcystins(-LR,-YR,-RR) were not found in riverbank filtered water compared to surface water in Nakdong River. DOC(Dissolved organic carbon) and Humics which are precursors of disinfection byproduct were also reported to be removed about 59% for DOC, 65% for Humics. Based on data analysis in riverbed filtration site in Hwang River, removal rate of each contaminant reaches to BOD 33.3%, TOC 38.5%, SS 38.9%, DOC 22.2%, UV254 21.2%, Total coliforms 73.8% respectively. Additionally, microplastics were also inspected that there was no obvious removal rate in riverbed filtered water compared to surface water in Hwang River.

Recently, the market competition has been fiercer due to the acceleration of technological change and the launch of intelligent products. In this situation, technology cooperation activities through networks rather than independent technological innovation activities of a single company or institution are recognized as a crucial strategy to gain competitiveness. Technology cooperation can take various forms depending on the target technology, and researchers have conducted performance analyses of technology cooperation types. However, there have not been data-based quantitative studies on the types and trends of technology cooperation for the target technology. In this paper, we explored the difference between the technology cooperation types by technology and time using the formal concept analysis method and co-patent information. In particular, the proposed methodology has been verified through the case study of electric vehicles, and it is intended to suggest the direction of technological cooperation according to specific technologies and cooperation targets in the future

PURPOSES : Recently, corrosion and deterioration of highway facilities have been increasing owing to the excessive use of deicers. This study aimed to find an optimal snow removal method to develop countermeasures for the problem of excessive deicer use and improve the efficiency of snow removal. METHODS : Theoretical investigations and experiments related to deicing were conducted to determine the differences between deicing chemical types and states. Based on regional weather patterns, the entire country was categorized into four groups: warm and heavy snow, warm and light snow, cold and heavy snow, and cold and light snow, and matched with each regional office of the Korea Expressway Corporation. RESULTS : Optimal snow removal methods were proposed considering regional characteristics and deicing chemical types and states. CONCLUSIONS : Different deicer types were proposed according to the region type, such as using only salt and salt/calcium chloride in the warm and cold regions, respectively. Second, plowing was more effective at lower temperatures. Third, liquid deicer spraying could reduce the amount of deicer used. A liquid deicer is suitable for preliminary spraying because its quick-acting properties are superior to those of a solid deicer, although its lasting properties are inferior to those of the solid deicer.

Recently, the government has provided support such as entering new markets, expanding sales channels, and supporting manpower, not just in the form of funding, to efficiently and effectively support limited national resources to improve corporate performance. In this study, we tried to find out the effect of government support for companies that have benefited from the Excellent Technology Research Center Project (ATC Project) and the World Class 300 project using propensity score matching. As a result of the analysis, the effect of government support for the ATC project became visible after the appointment period, while the effect of the World Class 300 project was insignificant. This means that when the size of the company is small, the effect of government support is more pronounced. This suggests that in order to maximize the effectiveness of government support, appropriate national policy interventions such as government innovation funding are needed when the size of the company is small. In this study, differences in the timing, performance indicators, and company size of policy support effects were found in the growth stage of a company from a mid- to long-term time series perspective, suggesting that support policies based on this need to be adjusted and redesigned.

본 연구에서는 어선의 운동성능을 향상하기 위해 부착되는 부가물의 조합과 파라미터 변경에 따른 어선의 자유 횡 동요 감쇠 와 저항 성능을 평가하였다. 성능 평가를 위해 전산유체역학(Computational Fluid Dynamics)을 이용한 수치해석을 수행하였으며, 주요 부가 물인 빌지킬과 선저킬의 조합과 치수 변경에 따른 횡 동요 주기와 감쇠 계수의 변화를 확인하였다. 선저킬의 경우 길이가 변화함에 따른 횡 동요 감쇠 계수의 변화가 상대적으로 크지 않음을 확인하였다. 반면 빌지킬의 경우 길이와 각도의 증가에 따라서 횡 동요 감쇠 계수가 증가함을 확인하였다. 4가지 부가물 조합 조건과 나선의 저항 성능을 비교하였으며, 부가물에 의한 어선의 자세와 압력분포의 변화로 인 해 저항이 증가함을 확인하였다. 본 연구 결과를 통해 부가물 크기와 배치가 어선의 운동 및 저항 성능에 미치는 영향을 확인할 수 있었 으며, 어선 적용 시에 도움이 될 수 있을 것으로 기대한다.

The air dilution olfactory method to measure complex odors needs to store and carry odor samples from the field sampling until the analysis in laboratories. Until the analysis of sample in the laboratory, odor dilution factor (odor sensitivity) in the sample bag may decrease over time depending on the characteristics of each odor substances. This is one of the limitation for the air dilution olfactory method. Thus, the air dilution device enable to measure without loss in complex odors of samples. Recently, many studies on the performance test of on-site air dilution devices, i.e., field olfactometer, has been conducted to figure out the feasibility of the field olfactometers. In this study, seven odor samples were collected from five odor emission source sites. And comparative analysis with the air dilution olfactory method was carried out to assess the field applicability of the olfactometer. As results, the performance of the field olfactometer used in this study is regared as the affordable method. The dilution factors from between two methods showed the similar values, indicating low values of standard deviations. In order to ensure the accuracy and precision of measurement data using the field olfactometer, methodology minimized variables (that may affect measurement) needs to establish.

The effects of punching treatment on mycelial culture and fruiting body productivity were investigated in a new Lentinula edodes cultivar, “Jadam”, in sawdust medium for the stable production of oak mushroom. As the punching volume and number increased, the weight loss rate and color difference increased and the L value decreased. After spawn inoculation, the sawdust medium temperature and CO2 concentration reached their highest values at 33 and 19 days of incubation, respectively. The O2 concentration showed the lowest value on the 14th day of incubation, which was the opposite pattern to the CO2 concentration. As the punching volume and the number increased, the medium temperature and O2 concentration increased, and the CO2 concentration decreased. Higher punching volumes and numbers resulted in higher temperatures and lower CO2 concentrations. The best fruiting body yield was 5 × 70 mm - 30 (punching diameter × depth - number), and the total yield after three cycles was 644.7 g.

A new spore-less cultivar Lentinula edodes ‘Daedam’ was bred from monokaryotic strains of ‘LE15401-24’ and ‘LE192118-10’. The optimum temperature for mycelial growth of ‘Daedam’ on potato dextrose agar was 22~25oC. Total cultivation period of the new cultivar, from inoculation to its first harvest, was 134 days, similar to that of the control cultivar ‘Hwadam’. Total yield of ‘Daedam’ was 222g per 3kg substrate, and was lower than that of control cultivar(266.0g). The fruiting body of ‘Daedam’ had a thick and small pileus and a longer stem compare to control cultivar. As a result of a analyzing the productivity of ‘Daedam’ on the different substrate types, the biological efficiency was 26.7% in the 1.2kg cylindrical substrate(CS), which was higher than that of the 3kg rod-type substrate(RS). 'Daedam' had a similar yield compared to 'Hanacham' in first fruiting body production, but the cultivation period was 40 days shorter. Therefore, 'Daedam' can only harvest fruiting bodies once, it is thought that it can be used as spore-less oak mushroom cultivar for short-term cultivation instead of 'Hanacham' in mushroom farms.

This study was conducted to reduce the phenomenon of the biased cultivation of certain mushroom varieties and to develop a competitive variety of Pleurotus nebrodensis. We have collected and tested characteristics of genetic resources from domestic and overseas varieties since 2015. We bred the domestic variety ‘Boram’. The optimal temperature was 26~29oC for mycelial growth and 15~18oC for fruit body growth temperature. This variety was similar to the control variety (Uram) in terms of the number of cultivation days and yield per bottle. The shape of the new cultivar was round, whereas that of the control group was spatula-like. The yield was 181.1 g/bottle, which was statistically similar to that of the control variety. When incubating the parent and control varieties, the replacement line was clear. Moreover, polymerase chain reaction analysis of mycelial DNA resulted in different band patterns between the parent and control varieties, confirming the hybrid species.