• Journal of the Architectural Institute of Korea Planning & Design
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• v.34 no.4
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• pp.45-55
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• 2018

The purpose of this study is to analyze common features and methodological differences of PN-spatial characteristics found in architectural theories and works of contemporary young architects in Japan, such as Sou Fujimoto, Yo shimada, Keisuke Maeda and Junya Ishigami. These architects have paid attention to space between nature and inner space and have tried to establish their own architectural theory on that. Such space is ambiguous and PN-spatial in a way that it has features of both nature and inner space. Ambiguousness is a characteristic of modern architecture and PN-spatial characteristics are one of the features of Japanese architecture. This study aims to analyze the architectural theories and works of contemporary young architects in Japan from the perspective of PN-space and to draw methodological differences and common features. Their theories and works have common features in terms of 'ambiguous spatial boundary', 'unregulated spatial territory', 'detoured circulation' and 'architectural motifs', but each has their own methodology. To sum up, the works and theories of the Japanese young architects contain the philosophy and discourse of modern architecture in general. To be sure, they clearly have characteristics of Japanese architecture, which needs to be studied constantly.

• Journal of the Earthquake Engineering Society of Korea
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• v.26 no.1
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• pp.23-30
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• 2022

This study proposed a simplified finite element analysis procedure for designing the nonstructural masonry wall in the out-of-plane direction. The proposed method is a two-step elastic analysis procedure by bilinearizing the behavior of the masonry wall. The first step analysis was conducted with initial stiffness representing the behavior up to the effective-yield point, and the second step analysis was conducted with post-yield stiffness. In addition, the orthotropic material property of the masonry was considered in the FE analysis. The maximum load was estimated as the sum of the maximum loads in the first and second step analyses. The maximum load was converted into the moment coefficients and compared with those from the yield line method applied in Eurocode 6. The moment coefficients calculated through the proposed procedure showed a good match with those from the yield line method with less than 6% differences.

• Journal of People, Plants, and Environment
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• v.24 no.4
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• pp.415-427
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• 2021

Background and objective: This study examined the changes in the cultural trend of use for green infrastructure in Seoul due to COVID-19 pandemic. Methods: The subjects of this study are 8 sites of green infrastructure selected by type: Forested green infrastructure, Watershed green infrastructure, Park green infrastructure, Walkway green infrastructure. The data used for analysis was blog posts for a total of four years from August 1, 2016 to July 31, 2020. The analysis method was conducted keyword frequency analysis, topic modeling, and related keyword analysis. Results: The results of this study are as follows. First, the number of posts on green infrastructure has increased since COVID-19, especially forested green infrastructure and watershed green infrastructure with abundant naturalness and high openness. Second, the cultural trend keywords before and after COVID-19 changed from large-scale to small-scale, community-based to individual-based activities, and nondaily to daily culture. Third, after COVID-19, topics and keywords related to coronavirus showed that the cultural trends were reflected on appreciation, activities, and dailiness based on natural resources. In sum, the interest in green infrastructure in Seoul has increased after COVID-19. Also, the change of green infrastructure represents the increased demand for experience that reflects the need and expectation for nature. Conclusion: The new trend of green Infrastructure in the pandemic era should be considered in the the individual relaxations & activities.

• International Journal of Advanced Culture Technology
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• v.11 no.3
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• pp.18-25
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• 2023

The COVID-19 pandemic has had a significant impact on the educational landscape for students across the globe, leading to a shift towards long-term online learning. This study aims to examine the changes in the health status of college and university students before and after the transition to online classes. We conducted a survey questionnaire among 200 students enrolled at K University in Gangwon-do, including participants from both the Department of Visual Optics and the Department of Physical Therapy. The survey employed a 5-point Likert scale to evaluate a range of health-related factors, including physical and mental well-being, alterations in lifestyle, and academic performance. Both male and female students experienced a decline in physical strength and exercise during the online class period, while mental health and overall happiness showed improvement, particularly among female students. Notable shifts in lifestyle emerged, including an increased usage of electronic devices and enhanced familial connections. The study also shed light on intriguing trends related to academic accomplishments and adherence to official quarantine guidelines. In sum, the findings of this study offer valuable foundational information for the maintenance of students' well-being during online learning, as well as the development of effective strategies for online education in future academic settings.

• Journal of Distribution Science
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• v.21 no.10
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• pp.85-95
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• 2023

Purpose: Virtual reality's impact on fashion distribution extends beyond singular transactions, facilitating the emergence of novel collaborations. As investigating the characteristics of fashion distribution channels in virtual reality, this study explores how the fashion industry can utilize virtual reality distribution channels to their maximum capacity while minimizing potential disadvantages. Research design, data, and methodology: The approach used to gather previous studies for this study adheres to the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) methodology. This method is widely acknowledged and recommended for its systematic and transparent approach to selecting relevant literature. This kind of literature search plays a vital role in a systematic evaluation as it informs the results. Results: The finding indicates consistently a total of eight kinds of characteristics of fashion distribution channels in virtual reality. The result means that the attributes of fashion distribution channels in virtual reality are causing significant changes in the fashion industry, revolutionizing the consumer experience, and redefining the parameters of creativity and collaboration. Conclusions: In sum, the global reach and accessibility of modern technology enhance the capacity of fashion companies to expand their market presence. This facilitates their participation in intercultural interactions and allows them to serve a wide range of customers.

• Journal of Ocean Engineering and Technology
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• v.36 no.6
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• pp.390-402
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• 2022

Offshore wind energy has become a major energy source, and various studies are underway to increase the economic feasibility of floating offshore wind turbines (FOWT). In this study, the characteristics of wave-induced motion of a combined wind-wave energy platform were analyzed to reduce the variability of energy extraction. A user subroutine was developed, and numerical analysis was performed in connection with the ANSYS-AQWA hydrodynamic program in the time domain. A platform combining the TLP-type FOWT and the Wavestar-type wave energy converter (WEC) was proposed. Each motion response of the platform on the second-order wave load, the effect of WEC attachment and Power take-off (PTO) force were analyzed. The mooring line tension according to the installation location was also analyzed. The vertical motion of a single FOWT was increased approximately three times due to the second-order sum-frequency wave load. The PTO force of the WEC played as a vertical motion damper for the combined platform. The tension of the mooring lines in front of the incident wave direction was dominantly affected by the pitch of the platform, and the mooring lines located at the side of the platform were mainly affected by the heave of the platform.

• Journal of Positioning, Navigation, and Timing
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• v.11 no.1
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• pp.1-9
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• 2022

Global Navigation Satellite System (GNSS) provides location information using signals from multiple satellites. However, a spoofing attack that forges signals or retransmits delayed signals may cause errors in the location information. To prevent such attacks, authentication protocols considering the navigation message structure of each GNSS can be used. In this paper, we analyze the authentication protocols of Global Positioning System (GPS), Galileo, and BeiDou, and compare the performance of Navigation Message Authentication (NMA) of the above systems, using several performance indicators. According to our analysis, authentication protocols are similar in terms of performing NMA and using Elliptic Curve Digital Signature Algorithm (ECDSA). On the other hand, they are different in several ways, for example, whether to perform Spreading Code Authentication (SCA), whether to use digital certificates and whether to use Timed Efficient Stream Loss-tolerant Authentication (TESLA). According to our quantitative analysis, the authentication protocol of Galileo has the shortest time between authentications and time to first authenticated fix. We also show that the larger the sum of the navigation message bits and authentication bits, the more severely affected are the time between authentications and the time to first authenticated fix.

• Journal of Advanced Navigation Technology
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• v.25 no.6
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• pp.543-549
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• 2021

In this paper, a robust transfer alignment method is proposed for a strapdown inertial navigation system(SDINS) with norm-bounded parametric uncertainties. The uncertainties are described by the energy bound constraint, i.e., sum quadratic constraint(SQC). It is shown that the SQC can be coverted into an indefinite quadratic cost function in the Krein space. Krein space Kalman filter is designed by modifying the measurement matrix and the variance of measurement noises in the conventional Kalman filter. Since the proposed Krein space Kalman filter has the same recursive structure as a conventional Kalman filter, the proposed filter can easily be designed. The simulation results show that the proposed filter achieves robustness against measurement time delay and high dynamic environment of the vehicle.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.42 no.1
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• pp.56-62
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• 2009

Feeding regimens was investigated for the growth and survival rate of juvenile Maroon clownfish (Premnas biaculeatus) in order to establish a seed production technique for this fish. Three types of feeding regimens were used, and growth and survival were highest under the following regimen: rotifer from day 0, Artemia from day 4, copepod from day 9 and artificial food from day 15, respectively (P<0.05). The average body lengths of the larvae were $6.76{\pm}0.55\;mm$, $7.63{\pm}0.50\;mm$ and $7.33{\pm}0.43\;mm$ in the Nannochloropsis oculata, Isochrysis galbana and control treatments conducted with 3 larvae/L, respectively (P<0.05). There were significant differences in larval growth between the treatments and controls conducted with 6 larvae/L and 9 larvae/L, respectively (P<0.05) but there was no significant difference between the N. oculata and I. galbana treatments (P>0.05). There were no significant differences in larval growth between the treatments at densities of 3-9 larvae/L (P>0.05). At highest density level, the larvae reared in I. galbana had the highest survival rate whereas survival was lowest in the control.

• Journal of Korean Society for Atmospheric Environment
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• v.17 no.5
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• pp.407-414
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• 2001

In this study, the absorption kinetics of $CO_2$onto a mixture of AMP (2-amino-2-methyl-1-propanol) MEA (monoethanolamine) water were investigated at 30 and 4$0^{\circ}C$ using a packed absorption tower. Solubility and absorption rate of $CO_2$into alkanolamine solutions and optimal condition of $CO_2$absorption process were investigated. The experimental conditions are as follows; temperature of 30 and 4$0^{\circ}C$, gas flow rate of 3ι/min for the absorption tower, and liquid flow rate of 0.1ι/min. Feed gas was a mixture of 85% $N_2$and 15% $CO_2$. The experimental results showed that AMP had greater solubilities and faster absorption rates than MEA and DEA. In addition, MEA had the fastest initial reaction rate. To improve the properties of AMP which have low initial reaction rate and high cost, AMP was used with MEA. The mixing ratio was also changed in constant total molarity of 1,2,3 and 4. The experimental results can be summarized as follows: (1) in solubility experiment, the addition of MEA in constant total polarity decreased the solubility of $CO_2$in AMP/MEA mixture. (2) from 0 to about 0.3 in mixing ratio, the solubility of $CO_2$in AMP/MEA mixture had little differences compared with the sum of solubility of AMP only and solubility of MEA only . (3) mixing ratio of 0.3 was found to be an optimal point with the fastest $CO_2$absorption rate.