• Journal of IKEEE
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• v.24 no.4
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• pp.1093-1097
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• 2020

This work describes the design and characterization of a Ku-band monolithic microwave integrated circuit (MMIC) power amplifier (PA) for satellite communication applications. The device technology used relies on 0.25 ㎛ gate length gallium arsenide (GaAs) pseudomorphic high electron mobility transistor (PHEMT) of wireless information networking (WIN) semiconductor foundry. The developed Ku-band PHEMT MMIC power amplifier has a small-signal gain of 22.2~23.1 dB and saturated output power of 34.8~35.4 dBm over the entire band of 13.75 to 14.5 GHz. Maximum saturated output power is a 35.4 dBm (3.47 W) at 13.75 GHz. Its power added efficiency (PAE) is 30.6~37.83% and the chip dimensions are 4.4 mm×1.9 mm. The developed 3 W PHEMT MMIC power amplifier is expected to be applied in a variety of Ku-band satellite communication applications.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.19 no.6
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• pp.118-133
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• 2020

Research interest in the Mobility-as-a-Service (MaaS) concept for enhancing users' mobility experience is increasing. In particular, dynamic pricing techniques based on reinforcement learning have emerged since adjusting prices based on the demand is expected to help mobility services, such as taxi and car-sharing services, to gain more profit. This paper provides a simulation framework that considers more practical factors, such as demand density per location, preferred prices, the distance between users and drivers, and distance to the destination that critically affect the probability of matching between the users and the mobility service providers (e.g., drivers). The aforementioned new practical features are reflected on a data structure referred to as the Matching Matrix. Using an efficient algorithm of computing the probability of matching between the users and drivers and given a set of precisely identified high-demand locations using HDBSCAN, this study developed a better reward function that can gear the reinforcement learning process towards finding more realistic dynamic pricing policies.

• Journal of the Korean Society of Clothing and Textiles
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• v.45 no.1
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• pp.28-45
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• 2021

The importance of smart clothing as a product is increasingly emphasized as further growth in the potential of the smart market is expected. There is a high understanding and sympathy for the potential of smart clothing in the mass consumer market; therefore, commercialization is not actively carried out. This study enhances the understanding of the development direction of products with a focus on technical benefits, in order for smart clothing to gain access to customers as wearable devices. This study identifies major technologies used in smart clothing through an analysis of the patent technology status of smart clothing in Korea. Smart clothing is divided into three types: passive smart, active smart and advanced smart clothing based on a reaction mechanism and functional scope. We present the smart clothing and discuss the product features for three types. According to research, smart clothing products were equipped with passive, active, and advanced smart systems as well as provided new services by converging big data and AI technologies, rather than only using technologies such as sensors, controls, and actuators. Future directions for new smart clothing product development is also discussed in the conclusion.

• Journal of IKEEE
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• v.25 no.4
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• pp.735-740
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• 2021

In this paper, we propose a new ESD protection device with high holding voltage with low current gain of parasitic NPN BJT by improving the structure of the existing LTDDSCR. The electrical characteristics of the proposed protection device were analyzed by HBM simulation using Synopsys' TCAD simulation, and the operation of the added BJT was confirmed by current flow, impact ionization and recombination simulation. In addition, the holding voltage characteristics were optimized with the design variables D1 and D2. As a result of the simulation, it was verified that the new ESD protection device has a higher holding voltage compared to the existing LTDDSCR and has a symmetrical bidirectional characteristic. Therefore, the proposed ESD protection device has high area efficiency when applied to an IC and is expected to improve the reliability of the IC.

• Fashion & Textile Research Journal
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• v.24 no.5
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• pp.493-504
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• 2022

This study aims to gain a deeper understanding of the fashion styles of underground rappers in China and South Korea. Due to rappers' fashion influence on modern fashion trends, research on rapper fashion has been conducted steadily in the field of apparel. Qualitative research methodologies including literature research and in-depth interviews were the primary techniques used to solve the research questions. In-depth interviews were conducted with 10 Chinese underground rappers and 10 Korean underground rappers to reveal and explore their fashion style and view of fashion. As a result, the participants' fashion styles were categorized into four styles: authentic hip-hop fashion style, popularized hip-hop fashion style, easy sports casual style, and trendy street style. Rappers from both countries consider that their identity as rappers can be demonstrated through their hip-hop fashion style. The influence of hip-hop culture and the popularity of rap music differs between China and Korea. It affects not only the rapper's musical characteristics, but also their fashion style. While Korean underground rappers' fashions style is trendier, Chinese underground rappers' fashions style displays stronger characteristics of hip-hop fashion. Due to the public's negative view of rappers, some Korean underground rappers intentionally try to hide their identity by wearing a fashion style that differs from the authentic rapper image. Understanding the fashion styles of underground rappers in Korea and China is expected to assist in predicting future hip-hop culture and rapper fashion trends.

• Asian Journal for Public Opinion Research
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• v.9 no.2
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• pp.142-160
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• 2021

The Internet and digital devices have become an important part of life among the youth (age 17-24) of today. During the COVID-19 pandemic in Indonesia, Internet use in youth increased by 19.3%, with an average usage of 11.6 hours per day. Youths gain a lot of opportunities from the Internet, but, it also exposes them to various risks. Therefore, there is a need for measures to make the Internet a safe place for youth, in a balanced way that addresses opportunities alongside risks, through digital literacy. It is expected that through digital literacy, youths can take advantage of online opportunities, without being subjected to any dangers. This study aims to examine the relationship between the digital literacy, online opportunities, and online risks of young people, while at the same time examining the influence of digital literacy on those online risks and opportunities. This study employed the quantitative study approach (explanatory study). Cross-sectional surveys and structured questionnaires were used for data collection. The results showed that youth's (age 17-24) monthly expenses, age, and education levels were important factors for digital literacy and online opportunity; also, the digital literacy variable plays an important role and affects online risk and opportunity positively. Digital literacy has a greater influence on online opportunities than it has on online risks. As youths spend more time online, they become more digitally literate, which can enable them to benefit more from new technology. Unfortunately, those with greater digital literacy cannot find a way to avoid risks while seeking opportunities.

• Journal of Korean Society for Quality Management
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• v.50 no.3
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• pp.593-615
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• 2022

Purpose: The purpose of this study was to explore and examine the factors influencing customer satisfaction and subscription intention in order to propose useful implication regarding subscription economy model. Methods: This study adopts the extended Unified Theory of Acceptance and Use of Technology model (UTAUT2) as the theoretical framework. On the basis of literature review, this study suggested 9 related hypothesis. To examine the hypothesis proposed, the study designed surveys with 32 questions and 456 answers were collected for the analysis. The study adopted a structural equation model and path analysis, using AMOS and SPSS programs. Results: The results of this study are as follow: All hypothesis except performance expectancy and effort expectancy have significant influence on customer satisfaction. Performance expectancy and effort expectancy have no significant influence on customer satisfaction and facilitate condition is significant but negatively associated with customer satisfaction. Conclusion: Result of this study is expected to suggest data regarding subscription economy and customer satisfaction for business with subscription model. In detail the result implies that highly sophisticated curation system would create more customer satisfaction and subscription intention rather than how a subscription-based platform is easily used. Moreover, curation system of subsription-based music platform should function with high accuracy on recommendation in a creative visual form in order to gain comparative advantage while most platforms have built own curation service.

• Proceedings of the Korea Water Resources Association Conference
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• 2023.05a
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• pp.319-319
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• 2023

Flows of water in the environment (e.g. in a river or estuary) generally occur in complex conditions. This complexity can hinder a general understanding of flows and their related sedimentary processes, such as erosion and deposition. To gain insight in simplified, controlled conditions, hydraulic flumes are a popular type of laboratory research equipment. Linear flumes use pumps to recirculation water. This isn't appropriate for the investigation of cohesive sediments as pumps can break fragile cohesive sediment flocs. To overcome this limitation, the rotating annular flume (RAF) was developed. While not having pumps, a side-effect is that unwanted secondary circulations can occur. To counteract this, the top and bottom lid rotate in opposite directions. Furthermore, a larger flume is considered better as it has less curvature and secondary circulation. While only a few RAFs exist, they are important for theoretical research which often underlies numerical models. Many of the first-generation of RAFs have come into disrepair. As new measurement techniques and models become available, there is still a need to research cohesive sediment erosion and deposition in facilities such as a RAF. New RAFs also can have the advantage of being automatic instead of manually operated, thus improving data quality. To further advance our understanding of cohesive sediment erosion and deposition processes, a large, automatic RAF (1.72 m radius, 0.495 m channel depth, 0.275 m channel width) has been constructed at the Hydraulic Laboratory at Chungnam National University (CNU), Korea. The RAF has the ability to simulate both unidirectional (river) and bidirectional (tide) flows with supporting instrumentation for measuring turbulence, bed shear stress, suspended sediment concentraiton, floc size, bed level, and bed density. Here we present the current status and future prospect of the CNU RAF. In the future, calibration of the rotation rate with bed shear stress and experiments with unidirectional and bidirectional flow using cohesive kaolinite are expected. Preliminary results indicate that the CNU RAF is a valuable tool for fundamental cohesive sediment transport research.

• Journal of the Korea Society for Simulation
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• v.19 no.1
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• pp.83-90
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• 2010

We describe a novel method for improving the performance of the UCC retrieval using content reputation and user reputation. The UCC retrieval is a part of the information retrieval. The goal of the information retrieval system finds documents what users want, so the goal of the UCC retrieval system tries to find UCCs themselves instead of documents. Unlike the document, the UCC has not enough textual information. Therefore, we try to use the content reputation and the user reputation based on non-textual information to gain improved retrieval performance. We evaluate content reputation using the information of the UCC itself and social activities between users related with UCCs. We evaluate user reputation using individual social activities between users or users and UCCs. We build a network with users and UCCs from social activities, and then we can get the user reputation from the network by graph algorithms. We collect the information of users and UCCs from YouTube and implement two systems using content reputation and user reputation. And then we compare two systems. From the experiment results, we can see that the system using content reputation outperforms than the system using user reputation. This result is expected to use the UCC retrieval in the feature.

• Animal Bioscience
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• v.36 no.7
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• pp.1067-1074
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• 2023

Objective: Better feed efficiency can be achieved by selecting rabbit genotypes with lower residual feed intake (RFI) under high ambient temperatures. Methods: Two genotypes of rabbits (Jabali, Saudi local breed and imported, Spanish V-line) were used to derive RFI and to investigate the relationship between RFI and productive traits. In total, 250 animals (125 each) were housed in individual wire mesh cages in a semi-closed rabbitry. Growth performance, feed criteria, carcass evaluation, biochemical blood analysis, and immune responses were determined. Results: Superiority in growth performance, feed efficiency, carcass characteristics, and cellular immunity was recorded in the Jabali breed compared to the V-line genotype. According to regression analysis, a significant effect of daily body weight gain was found, upon computing the expected feed intake in both genotypes. Moreover, mid-body weight^0.75 had a significant effect only in the Jabali breed. Positive correlation coefficients between RFI and dry matter feed intake or feed conversion ratio were found. The same trend in this relationship between RFI and productive traits was observed in some cases for both genotypes. An opposite trend in correlations was observed in the studied genotypes for some traits. Conclusion: The results suggest that the relationship between RFI and productive traits must be taken into consideration in rabbit breeding programs under the prevailing environment. However, further studies are required to investigate the effect of rabbit genotype and environmental factors on computing RFI.