• Environmental and Resource Economics Review
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• v.31 no.4
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• pp.645-668
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• 2022

Hydrogen energy is emerging as an important means of carbon neutrality in the various sectors including power, transportation, storage, and industrial processes. Fuel cell power plants are the fastest spreading in the hydrogen ecosystem and are one of the key power sources among means of implementing carbon neutrality in 2050. However, high volatility in system marginal price (SMP) and renewable energy certificate (REC) prices, which affect the profits of fuel cell power plants, delay the investment timing and deployment. This study applied the real option methodology to analyze how the dual uncertainties in both SMP and REC prices affect the investment trigger price level in the irreversible investment decision of fuel cell power plants. The analysis is summarized into the following three. First, under the current Renewable Portfolio Standard (RPS), dual price uncertainties passed on to plant owners has significantly increased the investment trigger price relative to one under the deterministic price case. Second, reducing the volatility of REC price by half of the current level caused a significant drop in investment trigger prices and its investment trigger price is similar to one caused by offering one additional REC multiplier. Third, investment trigger price based on gray hydrogen and green hydrogen were analyzed along with the existing byproduct hydrogen-based fuel cells, and in the case of gray hydrogen, economic feasibility were narrowed significantly with green hydrogen when carbon costs were applied. The results of this study suggest that the current RPS system works as an obstacle to the deployment of fuel cell power plants, and policy that provides more stable revenue to plants is needed to build a more cost-effective and stable hydrogen ecosystem.

• Smart Media Journal
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• v.11 no.11
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• pp.49-62
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• 2022

Recently, with the development of Smart City Solutions such as Big data, AI, IoT, Autonomous driving, and Digital twins around the world, the proliferation of various smart devices and social media, and the record of the deeds that people have left everywhere, the construction of Smart Cities using the "Big Data" environment in which so much information and data is produced that it is impossible to gauge the scale is actively underway. The Purpose of this study is to construct an objective and systematic analysis Model based on Big Data to improve the transportation convenience of citizens and formulate efficient policies in Urban Information and Public Transportation accessibility in sustainable Smart Cities following the 4th Industrial Revolution. It is also to derive the methodology of developing a Big Data-Based public transport accessibility and policy management Platform using a sustainable Urban Public DB and a Private DB. To this end, Detailed Living Areas made a division and the accessibility of basic living amenities of Gwangju Metropolitan City, and the Public Transportation system based on Big Data were analyzed. As a result, it was Proposed to construct a Big Data-based Urban Information and Public Transportation accessibility Platform, such as 1) Using Big Data for public transportation network evaluation, 2) Supporting Transportation means/service decision-making based on Big Data, 3) Providing urban traffic network monitoring services, and 4) Analyzing parking demand sources and providing improvement measures.

• The Journal of the Convergence on Culture Technology
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• v.9 no.1
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• pp.129-134
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• 2023

This study purports to investigate potential factors in various levels that affect respondents' use of youth facilities. Those levels include individual, family, and school. The data from 「2021 Youth Survey on Human Right Conditions」 will be analyzed. Hierarchical multiple regression analysis shows several results. First of all, respondents' age and level of human rights related information strongly influence respondents' use of youth facilities. Secondly, the analysis also shows that subjective well -being, abusive language and physical punishment from school faculty, and experience of human rights violation in schools affect the level of respondents' use of youth facilities. The order of effect sizes among significant variables are as follows; respondents' age, level of human rights related information, subjective well -being, abusive language and physical punishment from school faculty, and experience of human rights violation in schools. The independent variables in the model explain roughly 20 percent of whole variation of dependents variable.

• Journal of the Korea Society for Simulation
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• v.32 no.1
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• pp.1-11
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• 2023

Smart factory environments and digital twin environments are established, and today's factories accumulate vast amounts of production data and are managed in real time as visualized results suitable for user convenience. Production simulation techniques are in the spotlight as a way to prevent delays in delivery and predict factory volatility in situations where production schedule planning becomes difficult due to the diversification of production products. With the development of the digital twin environment, new packages are developed and functions of existing packages are updated, making it difficult for users to make decisions on which packages to use to develop simulations. Therefore, in this study, the concept of Discrete Event Simulation (DES) performed based on discrete events is defined, and the characteristics of various simulation packages were compared and analyzed. To this end, studies that solved real problems using discrete event simulation software for 10 years were analyzed, and three types of software used by the majority were identified. In addition, each package was classified by simulation technique, type of industry, subject of simulation, country of use, etc., and analysis results on the characteristics and usage of DES software were provided. The results of this study provide a basis for selection to companies and users who have difficulty in selecting discrete event simulation package in the future, and it is judged that they will be used as basic data.

• Journal of Service Research and Studies
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• v.13 no.2
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• pp.204-226
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• 2023

One of the most important types of Customer Empowerment Strategy (CES) is select empowerment, where firms allow customers to vote on a product to be marketed. However, there is limited research on the advantages and disadvantages of select empowerment. In particular, there are few studies on the composition of a voting system. This study analyzes customer participation behavior, such as willingness to vote and strategic voting (i.e., voting for candidates not based on utility orders), under the different voting systems: 1) the number of votes per customer (single or multiple), and 2) the number of final choices (single or multiple). Uncertainty is proposed as a mediator that links the voting system difference and customer participation. Two research hypotheses are tested using multiple linear regression analysis and a natural effects model based on data from two online experiments. As a result, the multiple voting system (i.e., multiple winners are selected by customer votes) shows a direct positive effect on willingness to vote and strategic voting behavior. In addition, the result shows that uncertainty insignificantly mediates the relationship between the voting system and customer participation. Academic and managerial contributions are discussed with several future research directions.

• Journal of the Korean Geotechnical Society
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• v.22 no.7
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• pp.73-83
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• 2006

The behaviour characteristics of Granular Compaction Pile (GCP) are mainly governed by the lateral confining pressure mobilized in the soft soil matrix to restrain the bulging failure of the granular compaction pile. The GCP method is most effective in soft soil with undrained shear strength ranging $15{\sim}50kPa$. However, the efficiency of this method reduces the more compressible soil conditions, which does not provide sufficient lateral confinement. In the present study, the GCP method reinforced with uniformly graded permeable concrete is suggested for the extension of application to the soft ground. Also, large triaxial compression tests are conducted on composite-reinforced soil samples for verification of availability of the suggested method and the settlement estimation method of the reinforced GCP is proposed. Furthermore, for the verification of the proposed method, predicted settlements by the proposed method are compared with results of 3-dimensional numerical analyses. In addition, parametric studies are performed together with detailed analyses of relevant design parameters.

• Journal of the Korean Society of Radiology
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• v.15 no.5
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• pp.697-704
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• 2021

It is hard to get Filaments which are materials of the 3D printing Fused Deposition Modeling(FDM) method as radiation shielding in Korea. and also related research is insufficient. This study aims to provide basic data for the development of radiation shields using 3D printing by evaluating the physical properties and radiation shielding capabilities of filaments containing metal particles. after selecting five metal filaments containing metal particle reinforcement materials, the radiation shielding rate was calculated according to the Korean Industrial Standard's protective equipment test method to evaluate physical properties such as tensile strength, density, X-ray Diffraction(XRD), and weight measurement using ASTM's evaluation method. In the tensile strength evaluation, PLA + SS was the highest, ABS + W was the lowest, and ABS + W is 3.13 g/cm³ which value was the highest among the composite filaments in the density evaluation. As a result of the XRD, it may be confirmed that the XRD peak pattern of the particles on the surface of the specimen coincides with the pattern of each particle reinforcing material powder metal, and thus it was confirmed that the printed specimen contained powder metal. The shielding effect for each 3D printed composite filament was found to have a high shielding rate in proportion to the effective atomic number and density in the order of ABS + W, ABS + Bi, PLA+SS, PLA + Cu, and PLA + Al. In this study, it was confirmed that the metal particle composite filament containing metal powder as a reinforcing material has radiation shielding ability, and the possibility of using a radiation shielding filament in the future.

• Journal of Bio-Environment Control
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• v.32 no.2
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• pp.132-138
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• 2023

The Gymnocalycium mihanovichii has been an important export item of Korean flower industry for a long time. Although there is a high demand for grafted cactus from overseas, its production for export is limited. In this study, the growth and marketable yield characteristics of Gymnocalycium mihanovichii 'I-Hong' were compared between soil culture and ebb-and-flow hydroponic system with single- or double-tier bench. As a result, hydroponic methods with single-tier bench resulted in higher fresh weight and glove diameter compared to other cultivation methods. In the ebb-and-flow hydroponic system, hydroponic system with double-tier bench of grafted cactus traits has a lower growth rate than other cultivations. However, the hydroponic system with double-tier bench of grafted cactus significantly increased the yield. In conclusion, the yield from hydroponic system with double-tier bench was better than soil cultivation method. Although there were some differences in color depending on the cultivation method, it was considered that there was no difference in appearance of Gymnocalycium mihanovichii 'I-Hong'. Our results suggest the cultivation methods to overcome production constraints, expand their exports, and improve the value-added characteristics of grafted cactus.

• Composites Research
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• v.22 no.2
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• pp.43-48
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• 2009

For the practical use of improved interlaminar fracture toughness by interleaving carbon non-woven tissue (CNWT), intelaminar fracture toughnesses of CFRP laminates with CNWT having different weights were experimentally investigated. A suitable weight of interleaved CNWT in CFRP laminates was discussed with Mode I and Mode II tests. Mode I and Mode II interlaminar fracture toughnesses (GIC and GIIC) were obtained by DCB and ENF tests. Six kinds of specimens with CNWT were prepared. The weights of CNWT per square meter for six types of specimens are $8g/m^2,\;10g/m^2,\;12g/m^2,\;16g/m^2,\;20g/m^2$, and $24g/m^2$, respectively. The mean GIC and GIIC values of six kinds of specimens were not substantially different from one another. Compared with the CFRP specimen, the mean GIC values of six kinds of specimens were slightly decreased. But the mean GIIC values increased tremendously at least twice by interleaving CNWT. It seems that there is no interrelationship between the interlaminar fracture toughnesses (GIC and GIIC) and the interleaving CNWT weights. Consequently, it would be desirable to use the CNWT of $8g/m^2$ among the six kinds of CNWTs to take advantage of the interlaminar fracture toughness improved by interleaving CNWT, because the CNWT of $8g/m^2$ is a lightweight and low-priced material.

• Journal of the Korean BIBLIA Society for library and Information Science
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• v.33 no.1
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• pp.371-401
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• 2022

If the blockchain means storing information in a distributed environment that cannot be forged or altered, it is mentioned that this is similar to what librarians collect, preserve, and share authoritative information. In this way, this study examined blockchain technology as a way to collect and provide reliable information, increase work efficiency inside and outside the library, and strengthen cooperative networks. This study attempted to propose various ways to utilize blockchain technology in book relations based on literature surveys and case studies in other fields. To this end, this study first analyzed the field and cases of blockchain application to confirm the possibility and value of blockchain application in the library field, and proposed 12 ways to utilize it based on this. The utilization model was proposed by dividing it into operation and service sectors. In the operation sector, it is a digital identity-based user record storage and authentication function, transparent management and traceable monitoring function, voting-based personnel and recruitment system, blockchain governance-based network efficiency function, and blockchain-based next-generation device management and information integration function. The service sector includes improved book purchase and sharing efficiency due to simplification of intermediaries, digital content copyright protection and management functions, customized service provision based on customer behavior analysis, blockchain-based online learning platforms, sharing platforms, and P2P-based reliable information sharing platforms.