• Progress in Superconductivity and Cryogenics
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• v.12 no.4
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• pp.24-30
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• 2010

The renewable energy source is considered as a good measure to cope with the global warming problem and the fossil energy exhaustion. The construction of electric power plant such as an offshore wind farm is rapidly increasing and this trend is expected to be continued during this century. The bulky and long distance power transmission media is essential to support and promote the sustainable expansion of renewable energy source. DC power cable is generally considered as the best solution and the demand for DC electric power has been rapidly increasing. Especially, the high temperature superconducting (HTS) DC cable system begins to make a mark because of its advantages of huge power transmission capacity, low transmission loss and other environmental friendly aspects. Technical contents of DC HTS cable system are very similar to those of AC HTS cable system. However the DC HTS cable can be operated near its critical current if the heat generation is insignificant, while the operating current of AC HTS cable is generally selected at about 50~70% of the critical current because of AC loss. We chose the specifications of the cable core of 'Tres Amigas' project as an example for our study and investigated the heat generation when the DC HTS cable operated near the critical current by some electric and thermal analyses. In this paper, we listed some technical issues on the design of the DC HTS cable core and described the process of the cable core design. And the results of examination on the current capacity, heat generation, harmonic loss and current distribution properties of the DC HTS cable are introduced.

• Journal of Hydrogen and New Energy
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• v.33 no.1
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• pp.8-18
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• 2022

With rapid industrialization and population growth, fossil fuel use has increased, which has a significant impact on the environment. Hydrogen does not cause contamination in the energy production process, so it seems to be a solution, but it is essential to find an appropriate storage method due to its low efficiency. In this study, Mg-based alloys capable of ensuring safety and high volume and hydrogen storage density per weight was studied, and Mg₂NiH_x synthesized with Ni capable of improving hydrogenation kinetics. In addition, in order to improve thermal stability, a hydrogen storage composite material synthesized with CaO was synthesized to analyze the change in hydrogenation reaction. In order to analyze the changes in the metallurgical properties of the materials through the process, XRD, SEM, BET, etc. were conducted, and hydrogenation behavior was confirmed by TGA and hydrogenation kinetics analysis. In addition, in order to evaluate the impact of the process on the environment, the environmental impact was evaluated through "Material Life Cycle Assessments" based on CML 2001 and EI99' methodologies, and compared and analyzed with previous studies. As a result, the synthesis of CaO caused additional power consumption, which had a significant impact on global warming, and further research is required to improve this.

• Economic and Environmental Geology
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• v.43 no.2
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• pp.197-205
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• 2010

Recently abrupt climate changes have been occurred in global and regional scales and $CO_2$ reduction technologies became an important solution for global warming. As a method of the solution shallow underground thermal energy storage (UTES) has been applied as a reliable technology in most countries developing renewable energy. The geothermal energy system using thermal source of soil, rock, and ground water in aquifer or cavern located in shallow ground is designed based on the concept of thermal energy recovery and storage. UTES technology of Korea is in early stage and consistent researches are demanded to develop environmental friendly, economical and efficient UTES systems. Aquifers in Korea are suitable for various type of ground water source heat pump system. However due to poor understanding and regulations on various UTES high efficient geothermal systems have not been developed. Therefore simple closed U-tube type geothermal heat pump systems account for more than 90% of the total geothermal system installation in Korea. To prevent becoming wide-spread of inefficient systems, UTES systems considering to the hydrogeothemal properties of the ground should be developed and installed. Also international collaboration is necessary, and continuous UTES researches can improve the efficiency of shallow geothermal systems.

• Journal of Energy Engineering
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• v.17 no.4
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• pp.241-246
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• 2008

Increase of $CO_2$ by using fossil fuels makes mainly global warming and the international efforts to reduce the $CO_2$ emission is being promoted. Absorption process using aqueous alkanolamine solution to remove acid components in the mixed gases has been used commercially. This method was used to remove $CO_2$ in the flue gas in recent years. $CO_2$ Absorption characteristics of several aqueous alkanolamine solutions such as MEA, DEA and AMP was studied by measuring vapor-liquid-equilibrium(VLE) and absorption velocity in this study. VLE measuring equipment, shell and reactor type, was used to acquire VLE data, equilibrium $CO_2$ pressure(${P_{CO_2}}^*$) and time at each pulse gas input. We also acquired the $CO_2$ absorption velocity by measuring the time to arrive the VLE at $40{\sim}80^{\circ}C$ and first gas input. The $CO_2$ absorption capacity of MEA 10wt% solution was higher than two alkanolamine solutions at $40^{\circ}C$ and the equilibrium $CO_2$ loading was 0.5. Absorption capacity was excellent as follows; AMP>DEA>MEA. But absorption velocity was fast as follows; MEA>AMP>DEA. Though good absorbent was considered by many variables, absorption velocity and capacity was more important factor.

• Journal of Hydrogen and New Energy
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• v.9 no.1
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• pp.8-15
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• 1998

The catalytic hydrogenation of carbon dioxide has been studied for the fixation of carbon dioxide to mitigate global warming problems, but it needed hydrogen, which the price is still high. Recently, the electrochemical reduction of carbon dioxide has been drawn attractions because carbon dioxide could be converted to the valuable chemicals such as methane, ethane and alcohols electrochemically in the electrolyte solution using a catalytic electrode. This system is simple because the water electrolysis and hydrogenation take place at the same time using the surplus electricity at midnight. In this work, a continuous electrochemical reduction system was fabricated, which was composed of the reduction electrode (copper or perovskite type, $2{\times}2cm^2$), reference electrode(platinum, $2{\times}6cm^2$), standard electrode(Ag/AgCl), and potassium bicarbonate electrolyte solution saturated with carbon dioxide. The quality and quantity of the products and reduction current were analyzed, according to the electrolyte concentration and electrode type.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.14 no.9
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• pp.4627-4634
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• 2013

Carbon dioxide is one of the main causes of global warming. In order to develop a novel absorbent, the characteristics of amino acid salts solution as a solvent for $CO_2$ capture in continuous process were investigated. The cost of $CO_2$ capture is almost 70% of total cost of CCS (carbon dioxide capture and storage). In the carbon dioxide capture process, process maintenance costs consist of the absorbent including the absorption, regeneration, degradation, and etc. It is very important to study the characteristics of absorbent in continuous process. In this study, we have investigated the properties of potassium L-lysine (PL) for getting scale-up factors in continuous process. To obtain optimum condition for removal efficiency of $CO_2$ in continuous process by varying liquid-gas (L/G) ratio, concentration of $CO_2$ and absorbent (PL) were tested. The stable condition of absorber and regenerator (L/G) ratio is 3.5. In addition, PL system reveals the highest removal efficiency of $CO_2$ with 3.5 of L/G and 10.5 vol% $CO_2$ ($1.5Nm^3/h$).

• Resources Recycling
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• v.32 no.2
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• pp.12-18
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• 2023

In 2018, the demand for silver (referred to as Ag) in the electrical and electronics sector was 249 million tons. The demand stood at 81 million tons in the solar module production sector. Currently, due to the rapid increase in solar module installation, the demand for silver is increasing drastically in Korea. However, Korea's natural metal resources and reserves are insufficient in comparison to their consumption, and the domestic silver ore self-sufficiency rate was as low as 2.2% as of 2021. This implies that a recycling technology is necessary to recover valuable metal resources contained in the waste plating solution generated in the metal industry. Therefore, this study compared and analyzed, the results of the impact evaluation through life cycle assessment according to an improvement in the process of recovery of valuable metals in the waste plating solution. The process improvement resulted in reducing GWP (Global Warming Potential) and ADP(Abiotic Depletion Potential) by 50% and 67%, respectively. The GWP of electricity and industrial water was reduced by 98% and 93%, respectively, which significantly contributed to the minimization of energy and water consumption. Thus, the improvement in recycling technology has a high potential to reduce chemical and energy use and improve resource productivity in the urban mining industry.

• Korean Journal of Organic Agriculture
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• v.10 no.3
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• pp.87-99
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• 2002

The development of insecticidal soaps made by various fatty acids and organic control for insect by using of insecticidal soap(fatty acid salts) were employed. And the results were as follows: 1. To determine the input volume of potassium hydroxide for saponification of fatty acids, there were compared to individual acid value of fatty acids. in case of coconut fatty acids for saponification was 266.3 mg of potassium hydroxide(266 g/1kg of fatty acid) was calculated. 2. To make the 25% soap content by coconut fatty acids, there was required for the 266g of potassium hydroxide and 3,459 liter of soft water. Then the liquor of soap was 4,644 liter. 3. The progress of insecticidal soap made by fatty acids was accomplished indirect heating and stirring reactor (1)to make the volume of potassium hydroxide solution and warming up(90$^{\circ}$) (2)input volume of individual fatty acid (3)more than 30 min stirring reaction (4)cooling progress. 4. Insecticidal value of insecticidal soap was observed more than 92% the dilution of 50 dilution solution in consecutive 5 days of 2 treatments of the 25% soap made by coconut fatty acids on the red pepper. And insecticidal value of insecticidal soap was observed more than 94% the 100 dilution solution in consecutive 5 days of 3 treatments of the 25% soap made by coconut fatty acids on red pepper and cabbage. 5. The treatment of two times of 25% soap made by coconut fatty acids at the 50 dilution solution and 100 dilution solution in spider mite on red bean has 100% insecticidal value. 6. There was no observation phytotoxic sypmtons on red pepper in field, except for 25% soap made by carprylic acid. 7. Over the two times over 0.1% in addition of isopropyl alcohol was to improvement the insecticidal effect, but there was no effect in addition of diatomaceous earth.

• Korean Journal of Animal Reproduction
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• v.23 no.4
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• pp.313-321
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• 1999

The purpose of these study was to investigate the use of a glass micropipette (GMP) as a vessel for vitrification of bovine IVP blastocysts, to compare the post-thaw survival rates of bovine blastocysts frozen in GMP with those frozen in OPS that have been previously investigated, and to improve the hatching rate following vitrification with GMP method. The GMP vessel permits higher freezing and warming rate than the OPS due to the higher heat conductivity of the glass and lower mass of the solution that contains the embryos. Groups of three bovine IVP blastocysts were sequentially placed into vitrification solution before being loaded into either the OPS or GMP vessels and immersed into L$N_2$within 20 to 25 sec. Post-thaw blastocysts were serially washed in 0.25 and 0.15 M sucrose in HM and TCM-199 for each 5 min, respectively, and then cultured in TCM 199 supplemented with 10% FCS for 24 h. The rate of blastocyst re-expanding did not significantly different for OPS (75.9%) and GMP (80.0%) methods (P＞0.05). The hatching rates in OPS (34.1%) and GMP (37.5%) methods were significantly lower than that in control group (54.3%) (P＞0.05). In addition, the rate of blastocyst re-expanding was significantly lower if blastocysts were vitrified in the wide portion of the micropipette rather than the narrow portion of the micropipette (83.3 vs 56.7%) (P＞0.05), even though three blastocysts were loaded per vessel. The hatching rate in 0.05% pronase solution treatment for 30, 60 and 90 see (45.9, 54.7 and 57.5%) were significantly higher than that in control (35.0%), even though there was not significantly different between 30 see and control. These results indicate that both vitrification vessels can provide high survival rates of bovine IVP blastocysts. However, the GMP vessel has the advantage over the OPS, in that the former does not need a cap to protect the vessel from floating after immersion in L$N_2$. The location of the embryos (narrow or wide portion of immersion) were considered to be limiting factors to the viability of bovine IVP embryos. The exposing in 0.05% pronase solution for 60 or 90 see can increase hatching rates of post-thaw bovine IVP blastocysts.

• The Journal of Art Theory & Practice
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• no.14
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• pp.53-83
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• 2012

This thesis is a study of artistic measures and climate refugees, based on Hack's World Climate Refugee Camp project. According to Hack, climate refugees appeared with the process of globalization. Hack claimed that the people who put climate refugees in danger are the industrialized nations, and therefore, their rejection of refugees is nonsense. He also stated that the fundamental solution would be the active participation of such nations. Thus, he travels around the world, encouraging participants and globalizing his project. Interestingly, the practical participation method of his climate calamity project is divided into four methods, which are all related to realizing the danger and presenting various solutions. First, the aesthetic of survival: the reason Hack focused on the warming trend and claimed that we have to accept the climate refugees as refugees comes from the thought that we are all potential refugees, and the anxiety that climate refugees may cause war in the end. The solution Hack found for surviving in such a world is to create "refugee camps" to notify people about the seriousness of climate change, and to put the "aesthetic for survival" in action. Second, a relation-oriented relationship: communication between Hack and the participants was done in various ways. They are experiencing a bond and emotions of an interrelationship through their actions in the experimental field, experiencing a new form of art, which they were not able to experience in a museum. Third, a utopian measure: Hack's utopian measure started from the fear of dystopia but Hack still believes that it is not only a dream, but that it can be realized. He claims that even though the start may be feeble, it is possible to rescue children from starvation and to treat climate refugees as proper human in the end, when communication and cooperation is done the right way and properly. Fourth, the aesthetic of global relation, the internet: the new solution Hack is trying on the internet is to make more people participate in his project. It is fate that "human are the wrongdoer and the victim at the same time", but according to Hack's opinion, social disaster can be avoided through effort and it is optimistic that we can give form to the culture revolution we are experiencing now. Hack's project illustrated the importance of daily life, compared to art inside a museum, through active participation of the people and opened up a new method of art through realistic responses to disasters. This is distinctive from the past exhibitions, where artists gave shape and form to ideals and an imaginary world, in that it shows that the artist and audience aim for creating a community-like structure, just like Bourriaud's art method. Hack's project of climate calamity illustrates that installation and action art is not only an art genre which shows installation and activities, but that it can include social and political issues and that it can be completed with the help of participants, consequently becoming a genre of modern art. Hack raises a question about art's identity through various descriptions. Artists as planners, who base their artworks on their subjectivity or the characteristics of a specific period, the people as participants, the duet of art work and play, human and human, and further, human and nature. The practical participation method, as a measure for "disaster", reveals the new art of the 21st century within Hack's artworks. Even though there are several problems with Hack's usage of art as a measure for disaster, it will actively open up a new page for the 21st century's art with the theme of disaster.