• Asian Journal of Innovation and Policy
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• v.11 no.1
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• pp.1-29
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• 2022

Climate action is at the top of the agenda in the international community, as demonstrated at the 2021 G7 Summit and the 2021 UN Climate Summit. Major developed countries are scrambling to make a transition to a green economy and create a new growth momentum. Following the Paris Climate Agreement in 2016, they focus on "carbon neutrality" as an effective means of tackling climate change. The Republic of Korea, a high-carbon economy, submitted its second Nationally Determined Contribution and announced carbon neutrality as a top policy priority. Accordingly, the country increases government budget in research and development (R&D) and science and technology (S&T) policies. Against this backdrop, this study analyzed policies on carbon-neutral S&T and R&D in major advanced countries. The analysis was made by identifying globally pending issues in carbon-neutral policies and climate technology. In addition, focus group interviews were conducted six times with 10 experts to come up with three R&D strategies and action plans for government-funded research institutes to achieve carbon neutrality. To be specific, the following measures were suggested. First, creative and innovative R&D programs are required to solve the problem of carbon emissions. Second, it is necessary to establish carbon neutrality policies and infrastructure which are sustainable to run and manage. Third, it is crucial to promote cooperation in climate technology based on excellence. In conclusion, the strategies proposed in this study are expected to provide directions and implications for policymakers, researchers, and scholars in science and technology to develop effective strategies to achieve national carbon neutrality.

• Journal of the Korean Society of Industry Convergence
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• v.26 no.5
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• pp.953-965
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• 2023

The stratospheric drones are developed to perform missions such as weather observation, communication relay, surveillance, and reconnaissance at 18km to 20km, where climate change is minimal and there is no worry about a collision with aircraft. It uses solar panels for daytime flights and energy stored in batteries for night flights, providing many advantages over existing satellites. The electrical and power systems essential for stratospheric drone flight must ensure reliability, efficiency, and lightness by selecting the optimal circuit topology. Therefore, it is necessary to analyze the circuit topology of various types of multi-level inverters with high redundancy that can ensure the reliability and efficiency of the motor driving power required for stable long-term flight of stratospheric drones. By quantifying the switch element voltage drop and the number and weight of inverter components for each topology, we evaluate efficiency and lightness and propose the most suitable circuit topology for stratospheric drones.

• Journal of Information Technology Applications and Management
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• v.26 no.4
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• pp.51-69
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• 2019

One of the most considerate phenomena of the era of the Fourth Industrial Revolution is the use of digital devices. Digitalization is rapidly advancing through all areas of industry and life. Customer journey with digitalization is looking totally different from previous customer journey. The research targets were users of fashion, automobiles, cosmetics and online shopping malls. We analyzed 300 people for each valid questionnaire. The results of the study are as follows. First, it has been proven that digital experience affects positive (+) impact on purchasing intention and positive (+) impact on recommending intention and negative impact (-) on switching intent and subsequently affects positive impact (+) to purchase and incase of switching intent, negative impact (-) to purchase. Unlike traditional methods such as SPC(Service Profit Chain), the Digital experience to Purchase process Chain (DPC) has been identified to be suitable in the digital age. Second, the digital satisfied group (5 score-very satisfaction) has shown same result as above. However the digital neutral group (even though 4 score- satisfaction in five-point scale), specially in a highly competitive industry, has different from the satisfied group and 3 score-normal is same as dissatisfied group. It means that this group is that If there is a high level of attractiveness of substitute goods, there is a high possibility of switching them. It has supported Jones and Sasser [1995] that there have been two types of loyalty of true long-term loyalty and what we call false loyalty in the highly competitive industry zone which is commoditization or low differentiation, many substitutes, low cost of switching. Identifying true loyalty and false loyalty is crucial to establishing a customer experience strategy. it is necessary to actively utilize long-term digital experiences strategy to increase the total satisfaction of digital experience through all of customer purchasing journey in order to enhance the digital customer experience. It is difficult to see the effect as a one-time event. It should be scaled over the entire customer purchase process over a long period of time, which can positively affect purchase intention, recommendation intention, and conversion intention. This is also why it is difficult for second-runners to overtake first-runners in a short period.

• Journal of the Korean Institute of Landscape Architecture
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• v.18 no.3 s.39
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• pp.115-135
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• 1990

The purpose of this study was to suggest an improvement proposal for colors in urban environment with special regard to the surface color and their situations of apartment buildings in Seoul. For this goal, 167 cases of different color types of apartment buildings were surveyed. And, the survey was performed in the view of color by areas, by localtion, by builder, by paint year, by built year, by appearance of building, and by surface texture to prove the influencing factors on the surface colors. These collected data analyzed and compared with the existing studies to find out the changing trend of colors. The results are as follows : 1) The use of neutral gray($26.4{\%}$) and warm color(YR, Y, GY; 56.4%) were dominant and the usage trend of higher 'value'(87.4%) and lower 'saturation'(73.0%) was obvious. Especially, the use of PB and P was noticeable. 2) In comparing the existing studies, the changing trend in the surface color pattern was found. That is, neutral gray was used dominantly in 1970's, warm color(YR, Y)in the middle of 1980's. In the end of 1980's, warm color were also used dominantly same as before and GY, PB, P were used noticeably with some rising tendency of higher 'value' and lower 'saturation' was obvious. 3) The results of analysis by localtion shows that the different color groups might exist in Seoul city. Neutral gray and YR were dominant in zone I. Warm colors(YR, Y, GY)were prevailed in zone II, III, IV. In zone V, many colors were evenly used. In zone VI, middle values at warm color were dominant. Progressively, these color groups with further study could be considered in the color management in urban environment possibly. 4) Surface color of apartment buildings were different from their builders. 5) Concerned with the painted year, the use of higher 'value' and lower 'saturation' was increased gradually with the change of times. 6) the analysis by the built year revealed that the 'value' of surface colors on the old buildings was lower than that of the new ones. 7) The 'value' of colors on the surface with texture was higher than that of the surface without texture. 8) In the combination of two colors, the use of 'value' with difference at the same 'hue' was found harmonions in many cases, but the 'saturation' in usage was included in the ambiguity (Moon & Spencer's term). The ambiguity in color harmony should be improved in the near future.

• Journal of the Korea Institute of Building Construction
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• v.12 no.5
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• pp.490-502
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• 2012

The use of recycled aggregate, even for low-performance concrete, has been very limited because recycled aggregate, which contains a large amount of old mortar, is very low in quality. To produce a high-quality recycled aggregate, removing the paste that adheres to the recycled aggregate is very important. We have conducted research on a complex abrasion method, which removes the component of cement paste from recycled fine aggregate by using both a low-speed wet abrasion crusher as a mechanical process and neutralization as chemical processes, and well as research on the optimal manufacturing condition of recycled fine aggregates. Subsequently, we evaluated the quality of recycled fine aggregate manufactured using these methods, and tested the specimen made by this aggregate. As a result, it was found that recycled fine aggregates produced by considering the aforementioned optimal abrasion condition with the use of sulfuric acid as reactant showed excellent quality, recording a dry density of 2.4 and an absorption ratio of 2.94. Furthermore, it was discovered that gypsum, which is a reaction product occurring in the process, did not significantly affect the quality of aggregates. Furthermore, the test of mortar using this aggregate, when gypsum was included as a reaction product, showed no obvious retarding effect. However, the test sample containing gypsum recorded a long-term strength of 25.7MPa, whereas the test sample that did not contain gypsum posted a long-term strength of 29.4MPa. Thus, it is thought to be necessary to conduct additional research into the soundness and durability because it showed a clear reduction of strength.

• Korean Journal of Agricultural Science
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• v.46 no.1
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• pp.67-78
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• 2019

The purpose of this study was to predict the water quality using the RNN (recurrent neutral network) and LSTM (long short-term memory). These are advanced forms of machine learning algorithms that are better suited for time series learning compared to artificial neural networks; however, they have not been investigated before for water quality prediction. Three water quality indexes, the BOD (biochemical oxygen demand), COD (chemical oxygen demand), and SS (suspended solids) are predicted by the RNN and LSTM. TensorFlow, an open source library developed by Google, was used to implement the machine learning algorithm. The Okcheon observation point in the Geum River basin in the Republic of Korea was selected as the target point for the prediction of the water quality. Ten years of daily observed meteorological (daily temperature and daily wind speed) and hydrological (water level and flow discharge) data were used as the inputs, and irregularly observed water quality (BOD, COD, and SS) data were used as the learning materials. The irregularly observed water quality data were converted into daily data with the linear interpolation method. The water quality after one day was predicted by the machine learning algorithm, and it was found that a water quality prediction is possible with high accuracy compared to existing physical modeling results in the prediction of the BOD, COD, and SS, which are very non-linear. The sequence length and iteration were changed to compare the performances of the algorithms.

• Economic and Environmental Geology
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• v.53 no.6
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• pp.695-701
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• 2020

This study aimed to monitor a pilot-scale vertical flow reactor (VFR) system being operated in long-term for water quality control of pH-neutral mine drainage containing Fe, Mn and As, discharged in D mine site. The treatment systems of VFR and zero manganese reactor (ZMR) consisted of sand/limestone, and steel slag/limestone, respectively. The systems were operated during about six months in order to evaluate their long-term treatment efficiency It was observed that both pH and alkalinity of mine drainage were remarkably increased and more than 98% of Fe, As and Mn ions was continuously removed during the tested period of time. In conclusion, the field results of this work demonstrated that the vertical flow reactor system can effectively treat mine drainage contaminated by Fe, As and Mn.

• Journal of Korean Institute of Industrial Engineers
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• v.41 no.3
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• pp.259-266
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• 2015

Among many energy resources, natural gas has recently received a remarkable amount of attention, particularly from the electrical generation industry. This is in part due to increasing shale gas production, providing an environment-friendly fossil fuel, and high risk of nuclear power. Because South Korea, the world's second largest LNG importing nation after Japan, has no international natural gas pipelines and relies on imports in the form of LNG, the natural gas has been traditionally procured by long term LNG contracts at relatively high price. Thus, there is a need of developing an Asian LNG trading hub, where LNG can be traded at more competitive spot prices. In a natural gas spot market, the amount of natural gas to be bought should be carefully determined considering a limited storage capacity and future pricing dynamics. In this work, the problem to find the optimal amount of natural gas in a spot market is formulated as a Markov decision process (MDP) in risk neutral environment and the optimal base stock policy which depends on a stage and price is established. Taking into account price and demand uncertainties, the basestock target levels are simply approximated from dynamic programming. The simulation results show that the basestock policy can be one of effective ways for procurement of LNG in a spot market.

• Clean Technology
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• v.19 no.3
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• pp.201-211
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• 2013

Biochar is charred materials generated during pyrolysis processes in the absence of oxygen using biomass, resulting in high carbon contents. In recent years, biochar has attracted more increasingly due to its potential role in carbon sequestration, renewable energy, waste management, soil amendment for agricultural use, and environmental remediation. Since biochar has a long-term stability in soil for thousands of years, biochar can be carbon negative compared to carbon-neutral biomass energy that decomposes eventually. Moreover, when biochar is applied to soil, crop production can be largely improved due to its high pH and its superior ability to retain water and nutrients. This paper review the research trends of biochar including the principles of carbon sequestration by biochar, its physico-chemical properties, and its applications on agricultural and environmental area.

• Journal of ILASS-Korea
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• v.14 no.2
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• pp.49-58
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• 2009

Non-edible vegetable oils instead of edible vegetable oils as a substitute for diesel fuel are getting a renewed attention because of global reduction of green house gases and concerns for long-term food and energy security. Out of various non-edible vegetable oils, karanja, mahua, linseed, rubber seed and cotton seed oils are selected in this study. A brief review of recent works related to the application of the above five vegetable oils and its derivatives in CI engines is presented. The production technologies of biodiesel based on non-edible vegetable oils are introduced. Problems in vegetable oil or biodiesel fuelled CI engine are included. In addition, future works related to spray characteristics of non-edible vegetable oil or biodiesel from it are discussed. The biodiesel fuel, irrespective of the feedstock used, results in a decrease in the emission of hydrocardon (HC), carbon monoxide (CO), particulate matter (PM) and sulphur dioxide ($SO_2$). It is also said to be carbon neutral as it contributes no net carbon dioxide to the atmosphere. Only oxides of nitrogen (NOx) are reported to increase which is due to oxygen content in the biodiesel fuel. The systematic assessment of spray char-acteristics of neat vegetable oils and its blends, neat biodiesel and its blends f3r use as diesel engine fuels is required.