• Journal of Powder Materials
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• v.30 no.4
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• pp.324-331
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• 2023

Lithium (Li) is a key resource driving the rapid growth of the electric vehicle industry globally, with demand and prices continually on the rise. To address the limited reserves of major lithium sources such as rock and brine, research is underway on seawater Li extraction using electrodialysis and Li-ion selective membranes. Lithium lanthanum titanate (LLTO), an oxide solid electrolyte for all-solid-state batteries, is a promising Li-ion selective membrane. An important factor in enhancing its performance is employing the powder synthesis process. In this study, the LLTO powder is prepared using two synthesis methods: sol-gel reaction (SGR) and solid-state reaction (SSR). Additionally, the powder size and uniformity are compared, which are indices related to membrane performance. X-ray diffraction and scanning electron microscopy are employed for determining characterization, with crystallite size analysis through the full width at half maximum parameter for the powders prepared using the two synthetic methods. The findings reveal that the powder SGR-synthesized powder exhibits smaller and more uniform characteristics (0.68 times smaller crystal size) than its SSR counterpart. This discovery lays the groundwork for optimizing the powder manufacturing process of LLTO membranes, making them more suitable for various applications, including manufacturing high-performance membranes or mass production of membranes.

• Journal of the Korean Society of Radiology
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• v.17 no.4
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• pp.557-564
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• 2023

In this study, 3D printing technology was used to compensate for the shortcomings of the use of lead, which has proven to have excellent shielding performance, and to control unnecessary human exposure. 3D printers can implement three-dimensional shapes and can immediately apply individual ideas, which has great advantages in maintaining technology supplementation while reducing the cost and duration of prototyping. Among the various special 3D printers, the FDM method was adopted, and the filament used for output was manufactured using a research extruder by mixing two materials, PLA (Poly-Lactic-Acid) and tungsten. The purpose was to verify the validity through dose evaluation and to provide basic information on the production of chapezones of various materials. The mixed filament was implemented as a morphological shield. Filaments made of a research extruder by mixing PLA and tungsten were divided into 10 %, 20 %, 30 %, 40 %, and 50 % according to the tungsten content ratio. Through the process of 3D Modeling, STL File storage, G-code generation, and output, 10 cm × 10 cm × 0.5 cm was manufactured, respectively, and dose and shielding ability were evaluated under the conditions of tube voltages of 60 kVp, 80 kVp, 100 kVp, 120 kVp, and tube currents of 20 mAs and 40 mAs.

• (The) Research of the performance art and culture
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• no.43
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• pp.229-261
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• 2021

On the musical stage in 2019, there were many works depicting the Japanese colonial period. This is due to 2019 the timeliness of the March 1st Movement and the centennial of the establishment of the Provisional Government of the Republic of Korea. The way of remembering and commemorating historical facts reflects the power relationship between memory subjects and the time, namely the politics of memory. Until now, stage dramas dealing with the era of Japanese rule have focused on the commemoration of modern national and national defense, including feelings of misfortune and respect for patriots. This study analyzed the metaphor of the memorials emphasized to the audience in the commemorative musicals Shingheung Military School, Ku: Songs of the Goblin, and Watch which were performed in 2019, and looked at how to adjust memories and memorials. The above works highlight the narratives of ordinary people as well as those recorded against the backdrop of the Manchurian Independence Movement and Hongkou Park, expanding the object of the commemoration. Through this, active armed resistance efforts, self-reflection and reflection were highlighted. The case of Shingheung Military School revealed the earnestness of ordinary people who led the independence movement through the movement of central figures. Ku: Songs of the Goblin revises memories by reproducing forgotten objects and apologizing through time slip. Watch has strengthened the spectacles of facilities through documentary techniques such as photography, news reels, and newspaper articles, but it also reveals limitations limited to records. In the 3.1 Movement and the 100th anniversary of the establishment of the Provisional Government of the Republic of Korea, devices that actively reveal that the "people's movement" is connected to the present. To this end, the official records reflected the newly produced values and memories and devoted themselves to the daily lives and emotions of the crowd. In addition, both empirical consideration and calligraphy were utilized to increase reliability. These attempts are meaningful in that they have achieved the achievement of forming contemporary empathy.

• 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 Service Research and Studies
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• v.13 no.1
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• pp.96-107
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• 2023

The objective of this study is to explore future issues that Chinese users, who have the highest mobile payment service usage rate in the world, will be most interested in. For this purpose, after collecting text data from a Chinese SNS site, it classifies major keywords into 4 types of future signals by using Keyword Emergence Map (KEM) and Keyword Issue Map (KIM). Furthermore, to understand the four types of signals in detail, it performs the qualitative analysis on text related to each signal keyword. As a result, it finds that the strong signal, which is rapidly growing in keyword appearance frequency during this research period, includes the keywords related to the daily life of Chinese people, such as buses, subways, and household account books. Additionally, it find that the signal that appears frequently now, but with a low increase rate, includes various services that can replace cash payment, such as hongbao (cash payment) and bank cards. The weak signal and latent signal, which appear less often than other two signals, includes the keywords related to promotion events or changes in service regulations. Its result shows that the mobile payment services greatly have changed user's daily life beyond providing convenience. Furthermore, it shows that, in the Chinese market, in which card payment is not common, the mobile payment services have the great potential to completely replace cash payment.

• Journal of the Korean Geotechnical Society
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• v.22 no.5
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• pp.83-91
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• 2006

Recently, the intensive rainstorm possibly induced by global warming plays a key role on the instability of railway adjacent slopes. The instability of slopes results as covering and loss of railway lines induced by slided soil mass. According to the site investigation on the failed slopes triggered by rainfall, low types of slope failure were observed: shallow, intermediate, gully erosion, and soil-rock interface failures. The observation reveals the different characteristics of slope failure depending on the thickness of soil layer, morphological features of slope, etc. Based upon the observations, flume tests were conducted to analyze the sliding mechanism of each failure. The variables of flume test are soil layer thickness, rainfall intensity, and morphology of slope under the constant condition of the percentage of fine, initial soil moisture content, slope angle and compaction energy. Test results show that shallow failure was mostly observed from the surface of the slope and caused by the soil erosion; in addition, compared to the other types of failure, the occurrence of initial erosion is late, however, the development of erosion is fast. In gully erosion failure, the collected water from the water catchment area helps erosion of the upper soil layer and transfer of residual corestone, which impedes the erosion process once the upper soil layers are eroded and corestone are exposed. The soil-rock interface failure shows the most fast initial erosion process among the failure types. Interestingly, the common feature observed from the different types of failure was the occurrence of the initial deformation near the toe of slopes which implies the existence of surbsurface flow along the downslope direction.

• Korean Journal of Environmental Biology
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• v.40 no.3
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• pp.290-300
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• 2022

A strain of Alexandrium species was established by isolating cells from Jangmok Bay, Korea. Its morphology and molecular phylogeny based on LSU rRNA gene sequences were examined. In addition, growth responses of this Alexandrium species to changes in temperature, salinity, and nutrient concentrations were investigated. This Alexandrium species from Jangmok Bay had a ventral pore on the 1', which was morphologically consistent with previously described Alexandrium tamarense and A. catenella. Phylogenetic analyses revealed that this isolate was assigned to A. pacificum (Group IV) within A. tamarense species complex. In growth experiments, relatively high growth rates and cell densities of A. pacificum (Group IV) were observed at 15℃ and 20℃. This species also grew under a wide range of salinity. This indicates that this Korean isolate of A. pacificum (Group IV) is a stenothermic and euryhaline species. In growth responses to changes in nutrient levels, enhanced growth rates and cell densities of A. pacificum(Group IV) were observed with additions of nitrate and phosphate. In particular, rapid uptakes of phosphate by A. pacificum (Group IV) were observed in experimental treatments, indicating that the increase in phosphate concentration could stimulate the growth of A. pacificum(Group IV).

• Knowledge Management Research
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• v.23 no.4
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• pp.113-132
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• 2022

The development of information and communication technologies (ICT) and changes in medical services centering on daily life have ushered in an era of self-management through the smartphone health management app (mHealth). This study identified the factors affecting mHealth use among older adults with diabetes. A structured survey was conducted using online and offline channels for 252 older adults who were over 65 and had diabetes. The collected data were subjected to hierarchical multiple regression analyses, and subjective health status, e-health literacy, and interaction terms of social support were inputted to verify moderating effect. The main results of this study are as follows. First, mHealth use among older adults with diabetes was higher in the male, type 2 diabetes, and younger age groups. Second, the higher was the e-health literacy, the higher was the mHealth use. Third, a negative moderating effect of social support was found in the relationship between subjective health status and mHealth use. We expect this study to provide researchers and managers interested in mHealth and older adults with diabetes, with valuable theoretical and practical implications. Furthermore, this study contributes to improving mHealth use among older adults with diabetes and building a digitally inclusive society.

• Knowledge Management Research
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• v.23 no.4
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• pp.177-205
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• 2022

Small- and medium-sized enterprises (SMEs) have strong incentives to engage in open innovation to enhance innovation efficiency and effectiveness due to their 'liability of smallness.' Previous research examined the performance effects of various open innovation practices, but whether coupled open innovation practices positively affect SMEs' firm performance is somewhat controversial. To resolve the issue, this study examined the effects of coupled open innovation activities on SMEs' firm performance using Heckman's two stage model to control endogeneity of the firms' self-selection bias in open innovation engagement. This study used the Korean Innovation Survey (KIS) 2020 collected by the Science and Technology Policy Institute (STEPI), and tested the effects of SMEs' coupled open innovation activities, R&D and non-R&D cooperation, on their innovative and financial performance indicators. The results showed that SMEs' R&D cooperation positively affects the new-to-market (NTM) product innovation only. Moreover, SMEs' non-R&D cooperation has positive effects on the product innovation, business process innovation, new-to-the-market product innovation, and new-to-firm (NTF) product innovation. However, the results showed that both R&D and non-R&D innovation cooperation activities have no significant effects on SMEs' financial performance indicators. This study contributes to research on SMEs' open innovation and provides insights for SMEs' managers and policymakers.

• The Journal of the Acoustical Society of Korea
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• v.41 no.6
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• pp.610-620
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• 2022

An acoustic vector sensor can simultaneously receive vector quantities, such as particle velocity and acceleration, as well as acoustic pressure at one location, and thus it can be used as a single input multiple output receiver in underwater acoustic communication systems. On the other hand, vector signals received by a single vector sensor have different channel characteristics due to the azimuth angle between the source and receiver and the difference in propagation angle of multipath in each component, producing different communication performances. In this paper, we propose a channel parameter-based weighting method to improve the performance of an acoustic communication system using a single vector sensor. To verify the proposed method, we used communication data collected from the experiment conducted during the KOREX-17 (Korea Reverberation Experiment). For communication demodulation, block-based time reversal technique which is robust against time-varying channels were utilized. Finally, the communication results showed that the effectiveness of the channel parameter-based weighting method for the underwater communication system using a single vector sensor was verified.