• Clean Technology
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• v.27 no.2
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• pp.107-114
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• 2021

Material Life Cycle Assessment (MLCA) was performed to analyze the environmental impact characteristics of the Mg₂NiH_x-5 wt% CaO hydrogen storage composites' manufacturing process. The MLCA was carried out by Gabi software. It was based on Eco-Indicator 99' (EI99) and CML 2001 methodology. The Mg₂NiH_x-5 wt% CaO composites were synthesized by Hydrogen Induced Mechanical Alloying (HIMA). The metallurgical, thermochemical characteristics of the composites were analyzed by using X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), specific surface area analysis (Bruner-Emmett-Teller, BET), and thermogravimetric analysis (TGA). As a result of the CML 2001 methodology, the environmental impact was 78% for Global Warming Potential (GWP) and 22% for Eutrophication Potential (ETP). In addition, as a result of applying the EI 99' methodology, the acidification was the highest at 43%, and the ecotoxicity was 31%. Accordingly, the amount of electricity used in the manufacturing process may have an absolute effect on environmental pollution. Also, it is judged that the leading cause of Mg₂NiH_x-5 wt% CaO is the addition of CaO. Ultimately, it is necessary to research environmental factors by optimizing the process, shortening the manufacturing process time, and exploring eco-friendly alternative materials.

• Economic and Environmental Geology
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• v.46 no.4
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• pp.339-344
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• 2013

Water vapor isotopes can be excellent tools for understanding complex mechanisms in the water cycle and atmospheric hydrological cycle and they can be applied to various fields of paleoclimatology, atmospheric science, hydrogeology, oceanography, and ecohydrology. Thus, studies of global or local transport of water vapor may be able to provide a very useful clue to better understand the movements of water and energy in the atmosphere, hydrosphere and biosphere. In this study, the isotopic compositions of water vapor have been observed for moisture transport during the passage of Typhoon Bolaven at Korea Polar Research Institute (KOPRI), Incheon, in the western part of Korea, from August 27 to August 29, 2012. In the clear sky, the isotopic compositions of water vapor at KOPRI exhibited relatively higher isotopic ratios, which were near isotopic equilibrium with sea surface water (${\delta}^{18}O$=-14‰). On the other hand, a largely depleted isotopic ratios in surface water vapor were observed in association with the passage of Typhoon Bolaven (approximately 10‰ depleted compared to the clear sky). The fact that the isotopic minima in water vapor are encountered during the onset period of the Typhoon Bolaven with increases of relative humidity, which is consistent with, so called, "the amount effect".

• Korean Journal of Agricultural and Forest Meteorology
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• v.15 no.3
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• pp.186-190
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• 2013

Soil respiration in forest ecosystems play an important role in global carbon cycle. This study was carried out to determine the annual variation of soil $CO_2$ efflux for 4 years in a broadleaved deciduous forest of the Geumsan (Mt.) Long-Term Ecological Research (GLTER) site in Southern Korea. The soil $CO_2$ efflux in the GLTER site showed annual variations with the fluctuations of annual mean soil temperature, but not with those of soil water content. The annual mean soil $CO_2$ efflux except for winter season was 0.32 g $CO_2\;m^{-2}h^{-1}$ for 2008, 0.40 g $CO_2\;m^{-2}h^{-1}$ for 2009, 0.41 g $CO_2\;m^{-2}h^{-1}$ for 2007, and 0.54 g $CO_2\;m^{-2}h^{-1}$ for 2010. The lowest soil $CO_2$ effluxin 2008 was associated with the lowest soil temperature ($2.0^{\circ}C$) in comparison with those of other years ($13.0-13.5^{\circ}C$). The exponential relationships between monthly soil $CO_2$ efflux and the corresponding soil temperature at the soil depth of 20 cm were significant ($R^2$ = 0.31-0.75, P < 0.05). The results indicate that the annual variation of soil $CO_2$ efflux was attributed to the variations of soil temperature rather than soil water content in the GLTER site.

• Korean Journal of Microbiology
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• v.50 no.2
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• pp.164-168
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• 2014

The ecosystem of the Arctic region has been increasingly affected by global warming. Archaeal ammonia monooxygenase alpha subunit coding gene (amoA) which is a key enzyme for nitrification was used to investigate the effect of runoff water of ice melt on microbial community of nitrogen cycle. The archaeal amoA genes at coastal area of Svalbard, Arctic region were PCR-amplified and sequenced after clone library construction. Analysis of archaeal amoA gene clone libraries suggested that the station 188 which is in the vicinity to the area of runoff water harbor lower ammonia-oxidizing archaeal diversity than the station 176 and 184. The average amino acid sequence identity within all archaeal amoA gene clones was 94% (with 91% nucleotide sequence identity). While all the clones of the station 188 were affiliated with Nitrosoarchaeaum clade containing strains isolated from low-salinity and terrestrial environments, about 45% of total clones of the station 176 and 184 were related to marine Nitosopumilus clade. Interestingly, other typical archaeal amoA gene clones of thaumarchaeal I.1b clade frequently retrieved from terrestrial environments was identified at station 188. Microbial community of nitrogen cycle in marine sediment might be affected by input of sediments caused by runoff glacier melt waters.

• Korean Journal of Environmental Biology
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• v.33 no.1
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• pp.1-6
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• 2015

Increased harmful algal blooms by cyanobacteria are threatening public health and limiting human activities related with freshwater ecosystems. Phosphorus (P) has long been suggested as a critical nutrient for cyanobacterial bloom through field research in Canada during the 1970s, proposing a P-based freshwater management guideline. However, recently, nitrogen (N) has also been highlighted as an impacting nutrient on cyanobacterial harmful algal blooms (CyanoHABs). Due to the intensive and frequent observation of Microcystis, this kind of paradigm shift from P limitation to season-dependent N or P limitation has an important implication for a dual nutrient management strategy in eutrophic freshwaters. Through recent international researches, general strategies to control CyanoHABs in lakes and reservoirs are as follows: a dual nutrient (N & P) reduction, wastewater collection and treatment, pre-treatment of influent water in buffer zones, dredging of sediment, reduction of residence time, algal collection, and precipitation and flocculation of cyanobacteria. In addition, sustainable and integrative freshwater algae management should be carried out, based on the ecological aspect, because cyanobacteria are not the target organism to be eradicated, but an essential microbial member in the freshwater ecosystem.

• Journal of Technology Innovation
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• v.26 no.2
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• pp.95-128
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• 2018

Since mid and late 2000s, the smartphones has been widely diffused and Korea ranked first in global smartphone market in 2011 thanks to its rapid adoption of Android operating system, technology capability accumulated in featurephone development, vertical integration on smartphone production and premium positioning. However, Korea fell behind because of the rise of another latecomer, China, in four years (2015) after it recorded the top position globally. How did the leadership change occurred in the smartphone industry so rapidly? In order to answer the question, we investigated three favorable windows of opportunity for the rise of China, which are technological, demand, and institutional, and the strategic responses of Chinese firms as well as the rigidity and complacency with the past success of Korean firms. Our findings contribute to the extension of 'catch-up cycle' theory as well as provide in-depth insights for strategies and policies settings to overcome the recent rise of China in information and communication technology sector for Korea.

• Information Systems Review
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• v.10 no.1
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• pp.213-235
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• 2008

Recent reports about economic structure and changes show that global economy changes to rely on service rather than manufacturing. This phenomenon can be explained in two ways: the growth of service industry itself and the increasing reliance on service by other industry areas. The importance of service is indicated by the fact that the contribution of research and development, marketing, and finance to the revenue generation of companies is getting greater than that of manufacturing. This change in the economic structure calls for researchers' attention on the importance of service and the service-based economy. In the service-based economy, firms are considered value proposition providers and consumers actual value creators so that the concept of co-value creation becomes a key thesis to study. However, there are a variety of definitions of service and diversified measurements of service anchored in the supplier-oriented understanding of service yet. This lack of understanding of the service and the economic paradigm change causes a lot of problems in the areas of service productivity, service quality, and service innovation. Even though a new movement called service science started and rigorously pursues the way of enhancing the understanding of the economic change and service productivity, there is no framework that provides a unified view about the new role of service, service productivity, service quality, and thus service innovation. This study proposes a unified framework to provide a structured view about service provision and to facilitate the research on service. The framework is built on the concepts from previous studies about service marketing and service science: service life cycle and service networks including value activity network, resource integrator network, and capability network. We hope this study can be used as the basis for future studies on service science.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.8 no.3
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• pp.295-306
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• 2003

Recently efforts are underway to analyze the impacts of anthropogenic $CO_2$ on the global environments and the amount of oceanic uptake increase. The East Sea is now viewed as a miniature ocean because its circulation pattern is similar to the ocean conveyer belt. The biological pump of the East Sea is a vital component to understand the carbon cycle quantitatively. In this paper, the biological pump is estimated utilizing the stoichiometric ratio between carbon and phosphorus. A simple phosphate budget model is constructed based on the seawater and dissolved oxygen box model that can simulate the recent structural change in deep water circulation of the East Sea. A model run from you 1952 to 2040 shows the steadily intensifying biological pump. Currently it exports about 0.016 Pg C yr$^{-1}$ , which corresponds to 35％ of the carbon introduced into the seawater by the air-sea exchange. An increased oxygen supply to the central water mass as a result of from the transition in the ventilation system might enhance the remineralization of sinking biogenic particles. This should strengthen the upward nutrient flux into the surface layer. Consequently, the biological sequestration of anthropogenic carbon is expected to increase with time. The estimated biological uptake of the anthropogenic carbon in the East Sea since the Industrial Revolution is estimated as 0.025 Pg C.

• Journal of Advanced Marine Engineering and Technology
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• v.38 no.7
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• pp.799-805
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• 2014

Recently, the regulations of the Local and Global for a variety of air pollution prevention has been enhanced by the steep rise in fuel oil prices. So, the appearance of Gas Fuelled Ships became necessary. In this study, we configured a regasification system which uses Eglycol water as a heating medium to evaporate before being supply fuel to the DF engine, then we analysed the system properties according to the Eglycol water mixing ratio. The results were as follows. When pressure, temperature, and flux of natural gas(NG) which are supplied to DF engines are uniformly kept, the higher mixing ratio of Eglycol is, the lower mixing specific heat of Eglycol water. And the cycle flux and electric power were 1.65 and 1.54 times more required. respectively, than water was used as the heating medium. Basic variables including mass flux according to the mixing ratio of Eglycol water, required electric power of operating fluid pumps, the temperature of natural gas which is supplied to the engine, and the heat exchanger's capacity were drawn from the gotten results.

• Journal of Christian Education in Korea
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• v.63
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• pp.183-219
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• 2020

The purpose of this study is to find out what their professionalism is and how their expertise grows among Christian alternative school teachers. Professionalism refers to the broad expertise such as specific knowledge, skills, and attitudes needed for a particular profession. The teacher expertise is also closely related to the life cycle of a teacher. The present study collected and analyzed the data using a mixed research method that combined a survey and interview. The survey, which involved 276 Christian alternative school teachers, asked about the current teacher's interest, the importance and retention of each element of professionalism, and, in addition, the level of external efforts and help in developing professionalism. The in-depth interview was conducted on 7 Christian alternative school teachers and identified the meaning of teacher professionalism, teacher quality and competencies, and environment for the professional growth. The results reveal that the professionalism recognized by Christian alternative school teachers is rather complex. It includes communication and relationship, calling and identity in addition to the curriculum and instruction expertise that reconstructs the curriculum from a Christian perspective. It is further found that teachers' decision to respond to the calling, subsequent continuous self-development, the teacher community that embodies such calling and efforts, and the school environment where autonomy and responsibility coexist, are equally important for their professional growth. Thus, in order to promote the professionalism of Christian alternative school teachers more effectively in the future, it would be necessary to provide programs that take the teacher's whole life cycle into account and are also directed to teachers themselves rather than to institutions. Considering the emphasis on the expertise in communication and relations, pre-service teacher education should focus not only on developing subject matter expertise, but also fostering communication and relational skills with students and other school community members.