• Journal of Korea Society of Industrial Information Systems
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• v.24 no.2
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• pp.15-23
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• 2019

High temperature superconducting (HTS) generators for wind power systems are attractively researched with the advantages of high efficiency and smaller size compared with conventional generator. However, the HTS generators have high Lorentz force problem, which acts on HTS field coils due to their high current density and magnetic field. This paper deals with characteristic analysis of the modularized HTS field coil for a 750 kW superconducting wind power generator according to field coil structure. The modularized HTS field coil structure was designed based on the electromagnetic and mechanical analysis results obtained using a 3D finite element method. The electromagnetic force of the module coil was also analyzed. As a result, the perpendicular and maximum magnetic fields of the HTS coils were 2.5 T and 3.9 T, respectively. The maximum stress of the supports was less than the allowable stress of the glass-fiber reinforced plastic material, and displacement was within the acceptable range. The design specifications and the results of the HTS module coil structure can be effectively utilized to develop large-scale superconducting wind power generators.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.22 no.3
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• pp.303-309
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• 2021

This study examined how consumers in their 20s and 30s perceive luxury goods, masstige brands, and counterfeits, which have high social value, and whether the propensity for conspicuous consumption and conformity can explain them. Consumers were classified based on the similarity of attitudes toward these brands and purchase intentions. The groups were compared on the sub-dimensions of conspicuous consumption and conformity. Clustering analysis identified four groups, and the MANOVA result confirmed the differences among the groups. Personality (F=4.282, p=.006) and brand orientation (F=23.178, p=.000) were positively related to luxury and masstige brands. Fashion orientation (F=8.376, p=.000) was high for both groups, which likes luxury and masstige brands very much, and which likes counterfeits. High-price orientation did not make any significant difference among the groups. Conformity (F=3.537, p=.015) was high for all the groups, except for the group that liked luxury and masstige brands and did not like counterfeits. This study comprehensively examined the attitudes and purchase intentions of luxury and masstige brands and their counterfeits and can be the groundwork for further research on brand categorization.

• Food Science and Industry
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• v.53 no.1
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• pp.69-83
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• 2020

For the development of the chitosan industry in Korea, the catch of red snow crabs caught on the east coast is rapidly decreasing. Therefore, it is urgent to develop raw materials that can replace the red snow crab as the top priority to solve the supply and demand problems, as well as wastewater treatment costs account for a large proportion of the cost of chitosan. In order to solve the problems, continuous research on biological extraction methods such as enzymatic extraction and microbial fermentation will increase production efficiency and lower unit cost as well as chemical extraction methods. Further efficient manufacturing method can be established. Establishing of novel techniques is indispensable for production of high-purity chitosan and the ability to regulate and separate the molecular weight, as well as joint research with industry, academia and research institute for the research and development of high-functional chitosan derivatives.

• Food Science and Industry
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• v.49 no.2
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• pp.25-33
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• 2016

우리나라의 발효식품 산업의 규모는 2010년 약 4조 원으로 식품 산업 전체의 4.0%정도이며, 이 중 전통 발효식품이 50.0% 수준으로 전체 식품 산업 대비 비중은 2.0%에 불과하지만, 발효제품의 세계 시장 규모는 2000년 152억 달러, 2010년 730억 달러로 급속한 성장으로 확대되고 있다. 국내 소금시장의 규모는 2010년 기준 1,300억 원이며, 전 세계적으로 나트륨 대체 염미제의 시장수요는 절실히 필요한 실정으로, 최근 2,000억 원대 규모를 유지하고 있는 간장 시장에서 염도를 낮춘 '저염 간장'매출 성장세를 보이고 있어 소금을 줄이는 식생활 개선에 대한 교육 홍보와 더불어 '나트륨 저감화 식품 개발의 필요성'이 국민건강증진, 경제성 측면에서 날로 커지고 있다. 또한, 2007년부터 웰빙 열풍으로 자연조미료 제품의 비중이 크게 늘어나는 추세이며, 100% 천연재료로 사용하여 소비자용 제품 출시 등 다양한 변화를 가져온 결과, 자연조미료 시장은 2008년 151억 3,200만 원의 매출규모에서 215억 2,600만원으로 무려 42.3%를 차지했으며, 저염을 위하여 활용하는 저염 소금도 연령대가 높아질수록 선호도가 높아지는 있다는 보고가 있다. 식품의약안전처의 '나트륨 저감화 사업'은 2012년부터 연차별로 가공식품의 나트륨 저감화 가이드라인을 개발하여 가공식품 생산업체들의 참여를 유도하며, 다양한 홍보를 펼쳐 2014년 6월 기준으로 165개 제품의 나트륨이 저감화 되었으며, 2015년에는 95종의 면류제품의 나트륨 함량이 약 20% 이상 저감되는 실적을 보여주었다. 여러 지역자체 단체들은 지역의 특성을 최대한 살려 다양한 발효산업 육성을 진행하고 있음에 영남권의 장류 업체를 대상으로 나트륨 섭취량을 줄일 수 있도록 '경북 발효식품 수출농업기술지원단'은 식품의약품안전처와 연계하여 지속적으로 가공식품 중 나트륨 저감화에 노력을 할 것이며 이에 대기업과 함께 중소기업들의 참여도를 높이기 위해 현장 컨설팅을 지역적으로 실시할 계획으로 각 지역별 업체들의 참여도를 높일 계획이다. 이를 통해 전통 발효식품이 기능성을 유지하면서 나트륨 함량을 줄인 건강식품으로 우리나라 식품산업 발전에 기여하고자 노력할 것이다. 향후 발효산업 중 한류의 매운맛, 김치 등을 시작으로 고성장이 기대되는 세계화 전략 품목이며 지역 농산물을 활용한 발효식품 세계화를 위하여 나트륨 저감화는 반드시 선행되어야 할 것으로 생각된다.

• Journal of IKEEE
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• v.25 no.2
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• pp.399-407
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• 2021

This paper proposes the DC-link voltage design method of Type 4 wind turbine that minimizes power loss and satisfies the High Voltage Ride Through(HVRT) function requirements of the transmission system operator. The Type 4 wind turbine used for large-capacity offshore wind turbine consists of the Back-to-Back converter in which the converter linked to the power grid and the inverter linked to the wind turbine share the DC-link. When the grid high voltage fault occurs in the Type 4 wind turbine, if the DC-link voltage is insufficient compared to the fault voltage level, the current controller of the grid-side converter can't operate smoothly due to over modulation. Therefore, to satisfy the HVRT function, the DC-link voltage should be designed based on the voltage level of high voltage fault. However, steady-state switching losses increase further as the DC-link voltage increases. Therefore, the considerations should be included for the loss to be increased when the DC-link voltage is designed significantly. In this paper, the design method for the DC-link voltage considered the fault voltage level and the loss is explained, and the validity of the proposed design method is verified through the HVRT function simulation based on the PSCAD model of the 2MVA Type 4 wind turbine.

• Journal of the Korean Institute of Landscape Architecture
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• v.49 no.1
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• pp.19-30
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• 2021

This research studied the effect of visual improvement of "72 Hour Project" that has regenerated small scale derelict spaces in Seoul through citizen participation. 29 projects built form 2016 to 2019 were analyzed. The research analyzed landscape image preference of before and after status of projects using 12 pairs of landscape adjectives. Basic statistical analysis, correlation analysis, factor analysis, cluster analysis, and ANOVA were performed based on the survey results. Since the satisfaction level of the projects compared with the before-condition was 3.63 higher than 3.00, it could be concluded that there was an meaningful effect of visual improvement after completion of the projects. As the result of the factor analysis, landscape adjective pairs were categorized into two factors: harmony and aesthetics. Through the cluster analysis, four clusters were formed and characteristics of each cluster were identified. As the result of rhe cluster analysis, the cluster with the high harmony level and the aesthetics level showed the highest overall satisfaction level. Comparing each cluster, it could be concluded that the factor of harmony was more important than the factor of aesthetics in evaluating the satisfaction level of projects. Analyzing qualitative aspects of project groups, spatially well-balanced design with generous vegetation areas was more effective in landscape improvement than artistic design with visually strong installations. Further researches based on behavior studies of actual users are required to compensate the limits of this research. This research can contribute to establish the improved direction of policies to regenerate various types of small scale derelict spaces.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.22 no.3
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• pp.1-12
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• 2021

Technologies for an MVDC(medium voltage direct current) distribution system are being considered as an effective alternative to overcome the interconnection delay issues of PV systems. However, the implementation of a DC distribution system might lead to economic problems because of the development of DC devices. Therefore, this paper deals with the scale of a PV plant based on its capacity and proposes hosting-capacity models for PV systems to establish a network to evaluate the feasibility of an MVDC distribution system. The proposed models can be classified as AC and DC distribution systems by the power-supply method. PV systems with hundreds of MW, dozens of MW, and a few MW can be categorized as large-scale, medium-scale, and small-scale models, respectively. This paper also performed modeling for an economic evaluation of MVDC distribution system by considering both the cost of AC and DC network construction, converter replacement, operation, etc. The profit was composed of the SMP and REC rate of a PV plant. A simulation for economic evaluation was done for the MVDC distribution system using the present worth and equal-principal costs repayment method. The results confirmed that the proposed model is a useful tool to evaluate economic issues of a DC distribution system.

• Knowledge Management Research
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• v.21 no.4
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• pp.59-88
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• 2020

This study is to examine the influence of Asian countries on the economic field, and to explain the characteristics and purposes of China's Belt and Road Initiative using data analysis. The purpose of this study is to identify and analyze the influence and characteristics of China's One-to-One Road Initiative on the economic sector by examining trade and investment in Asian countries adjacent to China. In particular, the One-to-One Road initiative is proceeding in a way that connects China and neighboring countries. It is to understand the dependence of the Asian countries in China on the Chinese economy. In addition, it is intended to derive implications by grasping and evaluating what the level is based on data. This study also attempts to grasp the influence and ripple effects of the one-on-one strategy on the Chinese economy and the North Korean economy, where dependence is deepening. Recently, the strategy for Asian countries through a one-to-one initiative in China has been restructured in the framework of the construction of the "21st century Maritime Silk Road" and emphasizes the cooperation mechanism led by the country. In progress of the one Belt and One Road, Chinese ICT companies are remarkable. This study looked at the influence of China's digital one Belt and One Road on Asian countries.

• Clean Technology
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• v.27 no.1
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• pp.69-78
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• 2021

Vegetable oils, such as palm oil and cashew nut shell liquid (CNSL), are used as major raw materials for bio-diesel in transportation and bio-heavy oil in power generation in South Korea. However, due to the high unsaturation degree caused by hydrocarbon double bonds and a high content of oxygen originating from the presence of carboxylic acid, the range of applications as fuel oil is limited. In this study, hydrotreating to saturate unsaturated hydrocarbons and remove oxygen in mixed bio-oil containing 1/1 v/v% palm oil and CNSL on monometallic catalysts (Ni and Cu) and bimetallic catalysts (Ni-Zn, Ni-Fe, Ni-Cu Ni-Co, Ni-Pd, and Ni-Pt) was perform under mild conditions (T = 250 ~ 400 ℃, P = 5 ~ 80 bar and LHSV = 1 h-1). The addition of noble metals and transition metals to Ni showed synergistic effects to improve both hydrogenation (HYD) and hydrodeoxygenation (HDO) activities. The most promising catalyst was Ni-Cu/��-Al2O3, and in the wide range of the Ni/Cu atomic ratio of 9/1~1/4, the conversion for HYD and HDO reactions of the catalysts were 90-93% and 95-99%, respectively. The tendency to exhibit almost constant reaction activity in these catalysts of different Ni/Cu atomic ratios implies a typical structure-insensitive reaction. The refined bio-oil produced by hydrotreating (HDY and HDO) had significantly lower iodine value, acid value, and kinetic viscosity than the raw bio-oil and the higher heating value (HHV) was increased by about 10%.

• Clean Technology
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• v.27 no.1
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• pp.61-68
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• 2021

Selective catalytic reduction (SCR) is widely used as a method of removing nitrogen oxide in large-capacity thermal power generation systems. Uniform mixing of the injected ammonia and the inlet flue gas is very important to the performance of the denitrification reduction process in the catalyst bed. In the present study, a computational analysis technique was applied to the ammonia injection system design process of a denitrification facility. The applied model is the denitrification facility of an 800 MW class coal-fired power plant currently in operation. The flow field to be solved ranges from the inlet of the ammonia injection system to the end of the catalyst bed. The flow was analyzed in the two-dimensional domain assuming incompressible. The steady-state turbulent flow was solved with the commercial software named ANSYS-Fluent. The nozzle arrangement gap and injection flow rate in the ammonia injection system were chosen as the design parameters. A total of four (4) cases were simulated and compared. The root mean square of the NH3/NO molar ratio at the inlet of the catalyst layer was chosen as the optimization parameter and the design of the experiment was used as the base of the optimization algorithm. The case where the nozzle pitch and flow rate were adjusted at the same time was the best in terms of flow uniformity.