• Applied Science and Convergence Technology
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• v.27 no.5
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• pp.95-99
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• 2018

We discuss the structural and optical characteristics of GaN nanowires (NWs) grown on Si(111) substrates by a plasma-assisted molecular-beam epitaxy. The GaN NWs with high crystal quality were formed by adopting a new growth approach, so called Ga pre-deposition (GaPD) method. In the GaPD, only Ga was supplied without nitrogen flux on a SiN/Si surface, resulting in the formation of Ga droplets. The Ga droplets were used as initial nucleation sites for the growth of GaN NWs. The GaN NWs with the average heights of 60.10 to 214.62 nm obtained by increasing growth time. The hexagonal-shaped top surfaces and facets were observed from the field-emission electron microscope images of GaN NWs, indicating that the NWs have the wurtzite (WZ) crystal structure. Strong peaks of GaN (0002) corresponding to WZ structures were also observed from double crystal x-ray diffraction rocking curves of the NW samples. At room temperature, free-exciton emissions were observed from GaN NWs with narrow linewidth broadenings, indicating to the formation of high-quality NWs.

• Food Science of Animal Resources
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• v.39 no.5
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• pp.780-791
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• 2019

This study aimed to extend the retention of flavor in coffee-containing milk beverage by microencapsulation. The core material was caramel flavor, and the primary and secondary coating materials were medium-chain triglyceride and maltodextrin, respectively. Polyglycerol polyricinoleate was used as the primary emulsifier, and the secondary emulsifier was polyoxyethylene sorbitan monolaurate. Response surface methodology was employed to determine optimum microencapsulation conditions, and headspace solid-phase microextraction was used to detect the caramel flavor during storage. The microencapsulation yield of the caramel flavor increased as the ratio of primary to secondary coating material increased. The optimum ratio of core to primary coating material for the water-in-oil (W/O) phase was 1:9, and that of the W/O phase to the secondary coating material was also 1:9. Microencapsulation yield was observed to be approximately 93.43%. In case of in vitro release behavior, the release rate of the capsules in the simulated gastric environment was feeble; however, the release rate in the simulated intestinal environment rapidly increased within 30 min, and nearly 70% of the core material was released within 120 min. The caramel flavor-supplemented beverage sample exhibited an exponential degradation in its flavor components. However, microcapsules containing flavor samples showed sustained flavor release compared to caramel flavor-filled samples under higher storage temperatures. In conclusion, the addition of coffee flavor microcapsules to coffee-containing milk beverages effectively extended the retention of the coffee flavor during the storage period.

• The Journal of the Convergence on Culture Technology
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• v.5 no.4
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• pp.203-208
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• 2019

Medical color graphic research will serve as the basis for globally expanding and disseminating the design quality of the company's products through the era of production of medical robots. This study was based on technologies and contents suitable for the era of medical robot bed expansion, universal medical color application, ergonomic color, etc. In addition, the medical bed robot's color research direction was presented from the perspective of universal design. Accordingly, a universal color design was proposed, taking the functions of a medical robot under development by a domestic company as an example. The characteristics of this robot bed can be divided into three types of functions: first, treatment characteristics for prevention of pressure ulcers with curative, second, automatic seat exchange with cleanliness for medical environment, and third, Convenient, which can implement patient transport. The main idea is to present a combination of functional colors appropriate for this. The resulting color analysis and universal color design techniques could be a useful methodology for illustrating the appearance and function of a modern medical robot bed.

• The Journal of the Convergence on Culture Technology
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• v.5 no.4
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• pp.445-450
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• 2019

Recently, consumers using cosmetics have a great interest in raw material safety. Among them, interest in natural preservatives is increasing, and as the demand for cosmetics excluding paraben preservatives increases, a method of replacing synthetic preservatives with antibacterial essential oils is being considered. The antibacterial effect of essential oils depends on the components, concentrations and interactions between the main active compounds. Effective preservatives should have antimicrobial activity against a wide range of strains even at minimal concentrations. All preservatives should be considered to increase skin concentration and cause skin irritation and allergic reactions. Consumers recognize that essential oils from nature are safe, but some should be careful because they can cause contact allergies or phototoxic reactions. As such, it is important to balance natural preservatives with maximum preservative effects and low toxicity. This paper describes the characteristics of essential oils focused on antibacterial properties, efficacy and safety as cosmetic preservatives.

• Journal of Digital Convergence
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• v.19 no.10
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• pp.377-382
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• 2021

A fuzzy relation between X and Y as fuzzy subset of X × Y was proposed by Zadeh. Subsequently, several researchers have applied the notion of fuzzy subsets to various branches of mathematics and computer sciences. Murali an Nemitz have studied fuzzy relations connected with fuzzy equivalence relations and fuzzy functions. Ounalli and Jaoua defined a fuzzy difunctional relation on a set. difunctional relations are versatile mathematical tool, which can be used in software design and in database theory. Their work have revealed the usefulness of difunctional relations in program specification and in defining program correctness. The main goal of this paper is to define a fuzzy deterministic relation on a set, characterize the fuzzy deterministic relation as its level subsets and investigate some properties in connection with fuzzy deterministic relation. In particular we prove that a fuzzy relation R is fuzzy deterministic iff R is a fuzzy function.

• International Area Studies Review
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• v.12 no.3
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• pp.467-492
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• 2008

This paper analyzes the specific product-basis trade structure between Busan and Japan using the recent 2000-2007 trade statistical data. Several specific product-basis trade structure tests such as intra-industry trade index and market comparative advantage index show that there are considerable differences in intra-industry trade structure between Busan and Japan. Furthermore, this paper found that Busan has high quality vertical intra-industry trade and horizontal intra-industry trade as well as low quality vertical intra-industry trade in trading with Japan. While Busan has the market comparative disadvantage in automobile-part products in Japan. This paper also examines the contribution to trade balance of Busan's exports and the movement of Busan's comparative advantage patterns in Japan. The comparative advantage appears to have overall stability and convergence properties using symmetric indices.

• Korean Journal of Materials Research
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• v.29 no.3
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• pp.167-174
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• 2019

To improve the performance of carbon nanofibers as electrode material in electrical double-layer capacitors (EDLCs), we prepare three types of samples with different pore control by electrospinning. The speciments display different surface structures, melting behavior, and electrochemical performance according to the process. Carbon nanofibers with two complex treatment processes show improved performance over the other samples. The mesoporous carbon nanofibers (sample C), which have the optimal conditions, have a high sepecific surface area of $696m^2g^{-1}$, a high average pore diameter of 6.28 nm, and a high mesopore volume ratio of 87.1%. In addition, the electrochemical properties have a high specific capacitance of $110.1F\;g^{-1}$ at a current density of $0.1A\;g^{-1}$ and an excellent cycling stability of 84.8% after 3,000 cycles at a current density of $0.1A\;g^{-1}$. Thus, we explain the improved electrochemical performance by the higher reaction area due to an increased surface area and a faster diffusion path due to the increased volume fraction of the mesopores. Consequently, the mesoporous carbon nanofibers are demonstrated to be a very promising material for use as electrode materials of high-performance EDLCs.

• Korean Journal of Materials Research
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• v.28 no.11
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• pp.640-645
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• 2018

The design of non-precious electrocatalysts with low-cost, good stability, and an improved oxygen reduction reaction(ORR) to replace the platinium-based electrocatalyst is significant for application of fuel cells and metal-air batteries with high energy density. In this study, we synthesize iron-carbide($Fe_3C$) embedded nitrogen(N) doped carbon nanofiber(CNF) as electrocatalysts for ORRs using electrospinning, precursor deposition, and carbonization. To optimize electrochemical performance, we study the three stages according to different amounts of iron precursor. Among them, $Fe_3C$-embedded N doped CNF-1 exhibits the most improved electrochemical performance with a high onset potential of -0.18 V, a high $E_{1/2}$ of -0.29 V, and a nearly four-electron pathway (n = 3.77). In addition, $Fe_3C$-embedded N doped CNF-1 displays exellent long-term stabillity with the lowest ${\Delta}E_{1/2}=8mV$ compared to the other electrocatalysts. The improved electrochemical properties are attributed to synergestic effect of N-doping and well-dispersed iron carbide embedded in CNF. Consequently, $Fe_3C$-embedded N doped CNF is a promising candidate for non-precious electrocatalysts for high-performance ORRs.

• Journal of Fashion Business
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• v.23 no.1
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• pp.14-24
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• 2019

Various types of functional bedding for inducing and maintaining sleep, are developed and launched with the importance of improving health through sleep emphasized currently. The purpose of this study is to examine development status and direction of functional bedding in the $4^{th}$ Industrial Revolution era, through systematic classification of elements of IoT-based smart bedding cases actively developed as functional bedding at home and abroad. Through previous research, literature and Internet data, characteristics and functional extension of smart bedding and the background of smart bed development was analyzed. And it was analyzed that smart bedding pursues recent functionalism and convergence of physical and digital concept such as IoT or AI, and also mental value to improve sleep quality. As bedroom where smart bedding place in has the private and limited characteristics and users are in sleep-conscious, that hard to ensure power and discomfort in carrying are moderated and the aesthetic elements are not very important, and that the smart bedding performance while sleeping were affected on developmental background. Based on CES case study and analysis on how smart beds are functionally expanded from conventional bedding, smart beds have gained information through digital sensing, and common properties that can be controlled anytime, anywhere, using a smart phone. Some set up the right environment and pose, while others stimulate nerves directly as active intervention. It is expected that smart bedding will be developed to cure user's body and mind, through active intervention when sleeping.

• The Journal of the Convergence on Culture Technology
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• v.5 no.3
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• pp.289-303
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• 2019

This paper presents research on furniture making based on Hojangjul, which is an engraving technique that highlights the wooden patterns of traditional furniture. Somokbang, one of the 12 workshops in Tongyeong, has used Hojangjul as an engraving technique since Imjinwaeran. It was inherited by the late Cheon Sang-won, who was No. 59 of National Important Intangible Cultural Properties, and developed into Samhojang, Ohojang, Seongtoinoimun, Hotguinoimun, and Gyeopguinoimun. It was then spread to Masan, Ulsan, and Gwangyang via marine routes and further into the inland areas via land routes, developing in various patterns and forms. The present study investigated and examined the making techniques and characteristics of Hojangjul engraved in joinery furniture in Tongyeong, Masan, and Ulsan in the Gyeongsang region and Gwangyang and Dongbok in the Jeolla region, thus shedding new light on the traditional techniques that have been gradually disappearing and promoting the transmission, inheritance, and development of the traditional techniques.