• Journal of the Korean institute of surface engineering
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• v.55 no.6
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• pp.460-468
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• 2022

Due to its high electrical conductivity, low contact resistance, good weldability and high corrosion resi-stance, gold is widely used in electronic components such as connectors and printed circuit boards (PCB). Gold ion salts currently used in gold plating are largely cyan-based salts and non-cyanic salts. The cya-nide bath can be used for both high and low hardness, but the non-cyanide bath can be used for low hardness plating. Potassium gold cyanide (KAu(CN)₂) as a cyanide type and sodium gold sulfite (Na₃[Au(SO)₃]₂) salt as a non-cyanide type are most widely used. Although the cyan bath has excellent performance in plating, potassium gold cyanide (KAu(CN)₂) used in the cyan bath is classified as a poison and a toxic substance and has strong toxicity, which tends to damage the positive photoresist film and make it difficult to form a straight side-wall. There is a need to supplement this. Therefore, it is intended to supplement this with an eco-friendly process using sodium sulfite sodium salt that does not contain cyan. Therefore, the main goal is to form a gold plating layer with a controllable hardness using a non-cyanide gold plating solution. In this study, the composition of a non-cyanide gold plating solution that maintains hardness even after annealing is generated through gold-palladium alloying by adding thallium, a crystal regulator among electrolysis factors affecting the structure and hardness, and changes in plating layer structure and crystallinity before and after annealing the correlation with the hardness.

• Korean Journal of Construction Engineering and Management
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• v.22 no.1
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• pp.90-97
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• 2021

Saemangeum Development is the largest national project in South Korea, which has been developed for an agricultural, economic and tourist area for 30 years from 1987. In order to convert power sources that used to depend on nuclear and thermal power to eco-friendly for carbon reduction, the government plans to construct a 2.1GW floating photovoltaic project by investing 4.6 trillion won, as a public-private project. For success of the Saemangeum floating photovoltaic project, economic feasibility should be checked. This study defined the factors (construction cost, electricity selling price, power generation and maintenance cost) that give a effect to the volatility of the floating photovoltaic payoffs, and analyzed the volatility of payoffs during 20 years operation period. NPV and option value of the project were calculated by applying an option to abandon. According to NPV analysis, it is determined that projects are difficult to invest. But this project has economic feasibility through real options analysis. This study is expected to help decision-makers in the economic analysis of floating photovoltaic projects by using the real options analysis.

• Journal of Korean Society of Forest Science
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• v.100 no.2
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• pp.283-291
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• 2011

The purpose of this study was to identify the public's preferences of different types of debris barriers and the impacts of construction materials, design, size, and planting on landscape preferences. On-site survey was carried out in Mt. Palgong during on December, 2009 and a total 122 visitors' data were analyzed. A total of 82 students Yeungnam and Donga University were also questioned in the classes during on December, 2009. Survey results showed that the debris barrier constructed with natural materials such as stone were more preferred and the level of planting around the debris barrier impacted most on the landscape preferences. The results imply that the importance of eco-friendly construction materials and methods has been increased in term of not only environmental conservation but also people's preferences. Therefore, the factors for enhancing landscape of debris barrier should be considered synthetically in terms of construction material, design, size, and planting level.

• Journal of Animal Science and Technology
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• v.63 no.2
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• pp.354-366
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• 2021

Limited data about the effects of various factors on forage quality and β-carotene content of rye produced in Korea are available, so this study investigated the effects of two preservation methods. Samples were collected from rye harvested every 5 days between April 25 and May 31, and comparisons were done among rye silage wilted for different periods of time and hay of three growth stages of rye. For the silage, dry matter (DM), acid detergent fiber (ADF), and neutral detergent fiber (NDF) contents increased with advanced maturity of rye, whereas crude protein, in vitro dry matter digestibility (IVDMD), total digestible nutrients (TDN), relative feed value (RFV), and DM loss decreased (p < 0.0001). Wilting increased the DM content and pH value significantly (p < 0.0001). Silage harvested at the heading stage had the lowest pH value (4.45), propionic acid (0.83 g/kg DM), butyric acid (0 g/kg DM), and fungi and yeast populations (3.70 Log CFU/g of fresh matter [FM]); conversely, it had the highest lactic acid (9.7 g/kg DM), lactic acid bacteria (LAB) (6.87 Log CFU/g of FM), total microorganisms (TM) (7.33 Log CFU/g of FM), and Flieg's score (70) (p < 0.0001). Wilting elevated LAB and TM populations, but it had no consistent effect on other fermentation products. Both delayed harvest and prolonged wilting decreased β-carotene content. Rye silage harvested around May 9 (heading stage) with 24 h of wilting was preferred for highland, Pyeongchang. For rye hay, advanced maturity decreased DM loss, IVDMD, TDN, and RFV, but it increased DM, ADF, and NDF significantly (p < 0.05). β-carotene was decreased by delay of hay-making. Consequently, to attain lower DM loss and higher hay quality, the harvest date of May 9 (heading stage) is recommended.

• Korean Journal of Agricultural Science
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• v.49 no.4
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• pp.771-783
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• 2022

In this study, the feasibility of alternative tractor Roll Over Protective Structure (ROPS) designed to evaluate conditions required for testing was confirmed. In accordance with Organization for Economic Cooperation and Development (OECD) code 4, the required load energy of the tractor ROPS was determined. First, the tractor ROPS test was performed and a repeated test was performed using a simplified ROPS as an alternative tractor ROPS. The test procedure is first rearward, second lateral, and last forward based on ROPS. The load test device consists of a load cell that measures force and a LVDT that measures deformation. Precision was confirmed by calculating the relative standard deviation of the simplified ROPS repeated test. Accuracy was analyzed by calculating the mean relative error between the mean measured values in the simplified ROPS test and the tractor ROPS test. As a result, the relative standard deviation was less than 2.5% for force and 3.3% for maximum deformation overall, showed the highest precision in lateral load. The mean relative error value for force measured at the lateral load of simplified ROPS was 0.5%, showing the highest accuracy. In the front load test, the mean relative error of maximum deformation was 20.5%, showing the lowest accuracy. The mean relative error (MRE) was high in the forward load test was because of structural factors of the ROPS. The simplified ROPS model is expected to save money and time spent preparing tractors.

• Korea Trade Review
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• v.42 no.5
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• pp.183-211
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• 2017

Recently, as the environment-friendly factors has become more important than before. In other words, the new model in trade has emerged as an important issue. At the same time, environmental trade is emerging as a new barrier due to the increasing international trade environmental regulation linked with environment. International trade environmental regulation has a huge impact on the whole industry, so if you can not cope with it in a timely manner, you can suffer great damage. Therefore, global export and import companies are required to manage green supply chains, and companies need to reestablish strategic systems throughout supply chain management with renewed awareness of the importance of eco-friendliness in the international trade environment. In this study, we investigated how companies perceive international trade environment regulation and how this affects the use of Green SCM.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.28 no.4B
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• pp.421-428
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• 2008

For last decades, the rapid coastal erosion process spreading along Korean peninsular has become a nuisance especially for tourism and local economy. Global warming and sea-level rise demand persistently new coastal protection strategies against the conventional methods using armored structures. In a view of this, Kweon et al. (2007) has proposed a new type of horizontal steel plates for an ideal candidate as eco-friendly detached breakwater systems for global warming era. The breakwater is composed of piles and horizontal porous plates that was devised for the optimized blockage effects and wave energy dissipations. This system provides outstanding performances as wave barrier and added advantages such as a rapid installation, an easy relocation, a perfect water circulation for the stagnation of pollutions in sheltered regions. The present experimental study focuses on the performance evaluations of the proposed system in wind wave conditions as a wave dissipator and reflector. The reflection, transmission, and energy dissipation of the random waves has been discussed in detail based on a newly proposed relation between wave steepness and a plate width normalized by wave length that are major factors affecting the wave transmission.

• Advances in nano research
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• v.15 no.4
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• pp.355-366
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• 2023

Biological corrosion, a crucial aspect of metal degradation, has received limited attention despite its significance. It involves the deterioration of metals due to corrosion processes influenced by living organisms, including bacteria. Soil represents a substantial threat to pipeline corrosion as it contains chemical and microbial factors that cause severe damage to water, oil, and gas transmission projects. To combat fouling and corrosion, corrosion inhibitors are commonly used; however, their production often involves expensive and hazardous chemicals. Consequently, researchers are exploring natural and eco-friendly alternatives, specifically nano-sized products, as potent corrosion inhibitors. This study aims to environmentally synthesize silver nanoparticles using an extract from Lagoecia cuminoides L and evaluate their effectiveness in preventing biological corrosion of buried pipes in soil. The optimal experimental conditions were determined as follows: a volume of 4 ml for the extract, a volume of 4 ml for silver nitrate (AgNO3), pH 9, a duration of 60 minutes, and a temperature of 60 degrees Celsius. Analysis using transmission electron microscopy confirmed the formation of nanoparticles with an average size of approximately 28 nm, while X-ray diffraction patterns exhibited suitable peak intensities. By employing the Scherer equation, the average particle size was estimated to be around 30 nm. Furthermore, antibacterial studies revealed the potent antibacterial activity of the synthesized silver nanoparticles against both aerobic and anaerobic bacteria. This property effectively mitigates the biological corrosion caused by bacteria in steel pipes buried in soil.

• Journal of the Korean Society of Industry Convergence
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• v.26 no.5
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• pp.793-802
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• 2023

The aim of this study analyzed changes in dietary habits and lifestyles before and after COVID-19 targeting adolescents, using the food consumption behavior survey (2019 vs 2021). In the change in health-related factors, height decreased overall, and a significant difference was especially evident in males. Awareness that functional foods and eco-friendly foods contribute to health has increased. Among the results of dietary behavior, the frequency of skipping breakfast showed that the rate of not skipping breakfast and the rate of skipping breakfast more than 5 times increased at the same time(p=0.019). The rate of eating out decreased significantly after COVID-19, and it was analyzed that schools and school cafeteria, as well as Street carts or restaurants and academy, all increased significantly as places where snacks were not consumed. In order to analyze changes in food-related lifestyle, it was grouped into convenience-seeking, quality/safety-seeking, taste-seeking, and health/safety-seeking. 'Small packaged or pre-processed products' decreased. On the other hand, items such as 'Safety rather than price when choosing food' and 'Don't eat food that could go bad' improved. 'Tend to eat regularly' was higher than 2021 compared to 2019. Also 'Tend to purchase HACCP and GAP-certified products' are increased. Because of COVID-19 changes in lifestyle have affected the diet of adolescents. The results of this study suggest that it can be used as a guideline establishment and nutrition counseling material for the formation of correct eating habits for adolescents in the future pandemic era.

• Journal of the Korea Society of Computer and Information
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• v.29 no.3
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• pp.191-198
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• 2024

Korea is an import and export-oriented economy that relies on shipping transportation, and sea ports play an important role in national economic growth. To secure and maintain the competitiveness of these ports, hardware and software investments are required, but policy support can also be expected to have an effect. This study identified the irrationality of the system by exploratory analysis of the port facility fee discount system for Ulsan Port, an energy hub port, and suggested improvement measures to resolve it.This study analyzed the volume of Ulsan Port and the reduction of port facility usage fees for about 10 years and identified irrational factors that despite a special port for liquid cargo, a considerable reduction for container cargo is concentrated, and even because it was a passing ship, 100% reduction for entrance and clearance fees were provided to them, which could cause serious moral hazard.. As a way to improve the port facility charge discount system at Ulsan Port, this study proposed strengthening support for eco-friendly activities to support containers, adjusting the reduction rate for passing ships, or improving the reduction and exemption application process.