• Journal of the Korea Organic Resources Recycling Association
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• v.30 no.4
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• pp.27-40
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• 2022

In this study, the anaerobic digestion potential and thermo-chemical pre-treatment were evaluated for efficient anaerobic co-digestion of dewatered sludge(DS) and food waste(FW). As a result, the degradable organic matter concentration and methane yield of FW were evaluated to 2.2 and 1.3 times higher than that of DS, respectively. In order to increase the amount of biogas production, it was determined that it is desirable to increase the mixing ratio of FW. The efficiency of thermo-chemical pre-treatment was evaluated for the reaction temperature, NaOH concentration, reaction time and mixture ratio. As a result of evaluation through pre-treatment efficiency and dehydration capacity, the optimum pre-treatment conditions were evaluated as follows: reaction temperature 140℃, NaOH concentration 60 meq/L, reaction time 60 min, mixture ratio 1:5(DS:FW). The gas production rate and methane yield increased 1.6 and 1.5 times, respectively, compared to before and after applying the optimum pre-treatment. Therefore, it is necessary to increase the mixing ratio of food waste for efficient anaerobic co-digestion of DS and FW. and it is necessary to increase the solubilization efficiency of waste by application of pre-treatment.

• International Area Studies Review
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• v.21 no.4
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• pp.195-222
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• 2017

This exploratory study analyses the factors, sources and effects of the regional competitive advantage of Jeju Island in Korea in global competition era. The competitive advantage of Jeju Province is analysed with the triple diamond model based on Porter's model for the competitive advantage of nations. The competitive advantage factors of Jeju Province are measured through the competitive advantage of the hospitality industry, which is one of the major industries of Jeju Island. These factors include outstanding natural landscape, domestic hospitality industry workforce, social overhead capital, massive domestic and international tourists, growth of related industries such as duty free shops and casinos, and coincidences such as Jeju Olle trail construction and Chinese government's international travel approval. Since these factors are based on local, domestic and international management resources, this study suggests that obtaining such resources is critical among Jeju hospitality industry in gaining the competitive advantage. Although the competitive advantage of Jeju hospitality industry is increasing, the organic connections with the regional economy are required for improvements on Jeju residents' quality of life. This study examines the factors and origins of competitive advantages on a regional level instead of a national level, and further investigates how the characters and origins of these factors affect the local economy. The results suggest that the triple diamond model is suitable for evaluating the regional competitive advantages.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.12 no.4
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• pp.41-53
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• 2002

Role Based Access Control (RBAC), which is a method, using role as an access control, has been popular with users and it is recognized as an effective method to replace the Discretionary Access Control and the Mandatory Access Control However, the existing Role Based Access Control Models have only been limited to the bureaucracy organization in which a distinctive hierarchy system was used, incorporating a stable structure and a standardized work system. Only in some parts, some access control models have been used, which supports 'Team' concept, such as Team Based Access Control Model. However, it did not incorporate the characteristics of the adhocracy organization, which is similar to the company's task force team, whose characteristics are organic, temporary, no standardized operation procedures, and many frequent changes. In this study, we have discussed the characteristics of the adhocracy organization which is different from the existing bureaucracy organization, and we have also discussed the problems related to when the existing access control models are used as the access control model for the adhocracy organization due to its characteristics. In addition, based on the problems, we have suggested an improved role based access control model for the adhocracy organization, and have come up with the solutions when any problems occur in the access control system.

• Korean Journal of Plant Taxonomy
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• v.51 no.2
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• pp.147-165
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• 2021

The flora of the vascular plants in Deoksesan Mt. and its adjacent areas, located at Inje-gun, Gangwon province, were surveyed for a total ten times from April of 2018 to July of 2020. The result of this survey revealed 457 taxa, consisting of 90 families, 287 genera, 404 species, 13 subspecies, 35 varieties, and 5 forms. Among them, 12 taxa were endemic plants to Korea, and 7 taxa were rare plants. Red list plants and those designated as controlled Korean biological resources, requiring special permission for export outside of the county, numbered 3 and 103 taxa, respectively. The floristic target species amounted to 83 taxa, specifically 8 taxa of grade IV, 26 taxa of grade III, 21 taxa of grade II, and 28 taxa of grade I. In addition, 14 taxa were classified as plants adaptable to climate change, and 4 taxa at their respective northern limits, first recorded in this study, were also investigated. Twenty-nine taxa of alien plants and 4 taxa of ecosystem disturbance species were also found in this area. Our results suggest that some species should be preserved and can serve as basic information with which to establish data on the preservation of resources, such as plant diversity and distributional changes on Deoksesan Mt.

• Journal of the Korean Recycled Construction Resources Institute
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• v.10 no.3
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• pp.314-320
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• 2022

The function of reinforcing fibers used in building materials is to maintain resistance to bending loads and to function for cracking caused by drying shrinkage. High-density fiber-cement composites are mainly used for linear plates and are used to increase bending resistance. Therefore, tensile properties, bonding strength with cement hydrate, alkali resistance, and the like are required. Recently, as the non-combustible performance has been strengthened, a function to minimize the occurrence of sparks during high-temperature heating has been added. Therefore, the use of organic fibers is limited. In this study, a study was conducted to replace polypropylene used as reinforcing fiber with hemp fiber with excellent heat resistance. Hemp fibers have excellent heat resistance, good affinity with cement, and excellent alkali resistance. Based on the total volume of polypropylene fibers used in the existing formulation, the non-combustible performance was compared and evaluated by using hemp fibers instead of the polypropylene fibers, and basic physical properties such as flexural strength were tested. As a result of conducting a non-combustibility and physical property test using hemp fibers with a fiber length of 7 mm using 2 % and 3 % by weight, it was found that there is no remaining time of the flame, and the flexural strength can be secured at 95 % level of the existing polypropylene fiber.

• Resources Recycling
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• v.30 no.2
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• pp.39-45
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• 2021

Spent photovoltaic module is one of the important resource of silver, while related research concerning silver recovery remains limited. In our previous research, HNO3 was utilized to dissolve Ag(I) and Al(III) from the spent silicon solar cells. In order to recover Ag(I) from the leachate of a silicon solar cell, the present study made use of a nitrate solution containing Ag(I) and Al(III), which was subjected to a solvent extraction process with 5,8-diethyl-7-hydroxydodecan-6-oxime (LIX63). Ag(I) was selectively extracted with LIX63 over Al(III) from the nitrate leach solution. Subsequently, quantitative stripping of Ag(I) from the loaded LIX63 was performed by using 20% ammonia water. The McCabe-Thiele plots for the extraction and stripping isotherms of Ag(I) were also constructed. Extraction and stripping simulation tests confirmed an Ag(I) extraction and stripping efficiency of >99.99% and 98.9%, respectively with high purity Ag (99.998%) and Al (99.99%) solution. A process flow sheet for Ag(I) recovery from the nitrate leach solution was proposed.

• Elastomers and Composites
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• v.37 no.4
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• pp.224-233
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• 2002

This study has investigated the flame retardant properties of EPDM rubber with the addition of various flame retardants. Carbon black, stearic acid, zinc oxide cross-linking agent were mixed with EPDM rubber to produce the base rubber E0 without the addition of flame retardants. Phosphorus flame retardant Tricrecyl phosphate(TCP) was added to E0 in 0.5, 1, 1.5, 2 phr to make E1~E4 samples and red phosphorus was added in 3, 6, 9, 12 phr to make E5~E8 samples. A flame retardant of the bromine family Decabromodiphenyloxide(DBDPO), and a chlorinated paraffin retardant of the chlorine family was added to E0 in 3, 6, 9, 12 phr to make E9~E12 and E13~E16 samples, repectively. Basic physical properties such as tensile strength, tear strength and hardness were measured for all the rubber samples with various flame retardant additions. There was no substantial differences. On the other hand, Oxygen index and UL94 were measured to study flame retardant properties. From oxygen index measurements E0 sample showed a value of 23.5%, indicating the improvement of flame retardant properties. Also from UL94 measurements, it was found that addition of red phosphorus resulted in maximum flame retardant effect. It was found that increasing the amount of addition resulted in decreasing combustion rate and improving flame retardant effect regardless of the kind of flame retardant.

• Journal of the Economic Geographical Society of Korea
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• v.26 no.3
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• pp.169-189
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• 2023

The study aims to synthesize the discussion of the innovation district and suggest an alternative to the governance system of the innovation district. Cluster policies that focus on industrial specialization, networking, value chains, and industrial ecosystems have shown some problems and limits in advanced industrial economies. The innovation district, suitable for the era of urban innovation, convergence of industry, housing, leisure, and related variety, emphasizes cooperation through the convergence of various innovations, workshops and industries, and communities. It is important to build a quintuple helix based on cooperative governance through public-private partnerships, integrate the physical and cultural atmosphere, and service industries that strengthen the place prestige. Beyond the industrial aspect, innovation districts can facilitate changes in urban amenities and lifestyles and creative atmosphere, such as diversity, lifestyle, charms, and openness, and promote social vitality and economic interactions. The governance of innovative districts can promote inter-organizational exchanges, and combinations. When knowledge is created through exchanges between companies, it also affects changes in the governance system, evolving from a rigid and centralized system to an open, dynamic, and organic system. Through the innovation policy, the existing Central Business Districts (CBD) can be able to be transformed into a Central Lifestyle Districts (CLD).

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.15 no.3
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• pp.115-123
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• 2010

The occurrence and variation of oxygen deficient water mass (ODW) in Namdae stream estuary, Yangyang were studied. Field observations for water properties and sediment environments were conducted at 5 stations of the estuary from April 2008 to November 2008. The coastal sandbar is developed at the estuary mouth, and there is a pool between the estuary mouth and about 2.3 km upstream of the estuary. The pool is relatively deep and narrow compared to riverbed of the estuary. The ODW was observed continuously in the pool from May to October. The ODW extends vertically up to 2 m depth in August, and maximum length of the ODW were about 2.3 km. Mean concentration of ignition loss (IL) and acid volatile sulfide (AVS) of sediment was 7.5~9.0%, $0.282{\sim}1.106\;mg/g{\cdot}dry$ wt, respectively. Ammonium concentration in the bottom layer during formation period of the halocline and the ODW was 4~23 times higher than that of surface layer. ODW was initiated by the introduction of seawater into bottom of the estuary pool to make a strong halocline, and then decomposition of organic matter within sediment accelerated the formation of the ODW.

• Journal of The Korean Association For Science Education
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• v.44 no.3
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• pp.273-299
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• 2024

This is a qualitative research study in which three families focused on scientific culture and conducted the process of forming a family fandom using ethnography. The ultimate goal of science education is the "cultivation of scientifically literate persons.", The researcher examines families who regularly participate in informal science educational programs, such as those offered by the National Marine Biodiversity Institute of Korea, to understand the cultural ans sociological significance of these activities as part of their daily routines. This study analyzes and summarizes the experiences of three families in different home environments as to the completion of the family fandom through the process of self-sustaining cultural practice formation through family education activities, and science activities. This study found that the process tword completion is more meaningful than the completion itself, in the context of science, culture, family and fandom. The findings of this study are as follows: 1) The process of forming a family fandom began with the individual purpose of each family member. 2) The process of fandom formation was created in an organic relationship through the interaction between parents and children, and the self-sustaining cultural practice strengthened the bond and expanded the consensus on scientific culture. 3) Parents and children together share scientific culture, and unique culture in the form of sharing in their own cultural life as becoming scientifically literate people. The self-sustaining cultural practice of selecting and enjoying these scientific activities is not simple consumption of popular culture, but the role of parents as cultural designers. This has conducted experiential consumption as "refined (or sophisticated) cultural consumers," and family leisure activities as meaning production of family members so it has social and cultural implications that can be developed into a scientific culture.