• Journal of Industrial Convergence
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• v.15 no.2
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• pp.27-36
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• 2017

In this study, we analyzed service quality factors of O2O delivery app based on Kano model and survey, and classified service quality into several dimensions. As a result of the analysis, the one dimensional quality factors were accurate information transmission, variety of restaurants, diversity of payment methods, diversity of menu selection, discomfort resolution, kindness of service, taste and quality of food, hygiene and cleanliness, Attractive quality factors such as updated information, reliable reviews, various ordering methods, fast delivery, brand image, discount point payment and accumulation. Although the must-be quality factor did not appear, it turned out that the discomfort resolution was close to the must-be quality factor. The indifferent quality factors were informational services, events and promotions. The O2O delivery app market is continuing to grow and competition is getting more and more intense. The results of this study will help O2O delivery app vendors to establish strategies to focus on certain quality of service factors.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.24 no.11
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• pp.1500-1506
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• 2020

In this paper, we study a scheduling problem based on reinforcement learning for overlay device-to-device (D2D) communication networks. Even though various technologies for D2D communication networks using Q-learning, which is one of reinforcement learning models, have been studied, Q-learning causes a tremendous complexity as the number of states and actions increases. In order to solve this problem, D2D communication technologies based on Deep Q Network (DQN) have been studied. In this paper, we thus design a DQN model by considering the characteristics of wireless communication systems, and propose a distributed scheduling scheme based on the DQN model that can reduce feedback and signaling overhead. The proposed model trains all parameters in a centralized manner, and transfers the final trained parameters to all mobiles. All mobiles individually determine their actions by using the transferred parameters. We analyze the performance of the proposed scheme by computer simulation and compare it with optimal scheme, opportunistic selection scheme and full transmission scheme.

• Journal of dental hygiene science
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• v.21 no.1
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• pp.1-7
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• 2021

Background: Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is transmitted primarily through droplets, and dental practitioners are at risk of occupational exposure to SARS-CoV-2 infection owing to direct contact with the patient's mouth, aerosols from dental procedures, and saliva. Wearing a mask is believed to be the best method of protection against infection, and a systematic literature review was conducted on whether the dental masks used in dentistry are effective in preventing Coronavirus Infectious Disease-19 (COVID-19). Methods: We used PubMed, Google Scholar, DBpia, NDSL, and KISS databases for this study. Of the 917 documents narrowed down by the search terms "Coronavirus, COVID-19, and dental," 83 documents were collected and studied. Ultimately, 42 of these papers were selected for analysis after considering duplication from the flow chart of the literature selection process. Results: While dental masks are often used when treating patients with unknown COVID-19 status, the Ministry of Food and Drug Safety stated that the use of dental masks is insufficient in preventing cross-transmission of COVID-19; instead, it was recommended that N95 masks, which correspond to KF94 masks, should be worn daily. On the other hand, wearing a dental mask and following precautions such as hand hygiene may not pose a significantly higher risk of infection than wearing an N95 mask when treating COVID-19 patients. Conclusion: There is an ongoing discussion regarding the use of dental masks when treating dental patients, and many argue that different types of masks should be selected according to the degree of infection and the individual's respiratory condition. By considering the safety and efficacy of dental masks in preventing infection, improvements can be made in the management of COVID-19 and dental-related infections.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.21 no.4
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• pp.37-42
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• 2021

NOMA (Non-orthogonal multiple Access) system has been focused on the next generation cellular system for higher spectral efficiency. However, this requires user scheduling as the NOMA system is a multi-user system which accesses simultaneously. There are two representative scheduling schemes, proportionate scheduling (FP) and cumulative distribution function (CFD) scheduling. The PF scheduling is applied, the cell edge user is hard to obtain a transmit opportunity. Recently, CDF scheduling is obviously noted that it offers the same possibility of transmission for a user regardless of the location in a cell. We consider an uplink NOMA system with CDF scheduling, and obtain the channel access probabilities, the outage probabilities of the system with different number of users and different kinds of weights through simulation. The results indicate that the likelihood of each user accessing the channel is the same and the probability of failure decreases as the number of users increases. We found that the effect of the probability of failure is negligible as the weight of the cell edge user increases.

• The Journal of the Korea Contents Association
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• v.22 no.1
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• pp.1-9
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• 2022

The purpose of this study is to comprehensively consider the challenge contents enjoyed based on SNS through the concept of Gamification and MDA framework. Regardless of the top-down and bottom-up divisions, in common, the participants show an active figure leading the creation and enjoyment of contents. As a result of analyzing the challenge contents using the MDA framework, the mechanics of 'relative level', 'challenge with expressive purpose', and 'Paidia rules' were found. This leads to the dynamics of participants who express an inner sense of achievement such as 'selection and competition for better expression' and 'selflessness and superiority', creating an environment where they can continuously participate in the challenge contents. Lastly, looking at the aesthetics of the challenge contents, it can be seen that participants are actively forming a play culture that leads the creation and enjoyment of contents. This phenomenon has resulted in breaking down the hegemony of content creation and distribution, which was the responsibility of society in the field of information transmission and commercial advertising.

• Clinical and Experimental Reproductive Medicine
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• v.49 no.1
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• pp.9-15
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• 2022

The angiotensin-converting enzyme 2 receptor (ACE2) appears to be widely expressed in cells in the testes, predominantly in spermatogonia, Sertoli cells, and Leydig cells, and its co-expression with transmembrane protease serine 2 (TMPRSS2) is essential for the entry of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). For this reason, the male reproductive system could be considered a potential target for SARS-CoV-2, as well as a possible reservoir of infection. However, to date, there is very little evidence about the presence of SARS-CoV-2 in semen and testicular samples. The aim of this paper was to review the current evidence regarding the impact of SARS-CoV-2 on male fertility and sexual health, with a particular focus on reproductive hormones, the presence of the virus in seminal fluid and testis, and its impact on fertility parameters. We found very limited evidence reporting the presence of SARS-CoV-2 in semen and testicular samples, and the impact of SARS-CoV-2 on reproductive hormones and fertility parameters is unclear. The quality of the examined studies was poor due to the small sample size and several selection biases, precluding definitive conclusions. Hence, future well-designed prospective studies are needed to assess the real impact of SARS-CoV-2 on male reproductive function.

• Health Policy and Management
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• v.32 no.3
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• pp.304-316
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• 2022

Background: As prevention of coronavirus disease 2019 (COVID-19) transmission in healthcare settings has become a critical component in its effective management, COVID-19 specific infection prevention and control (IPC) guidelines were developed and implemented by numerous countries. Although largely based on the current evidence-base, guidelines show much heterogeneity, as they are influenced by respective health system capacities, epidemiological risk, and socioeconomic status. This study aims to analyze the variations and concurrences of these guidelines to draw policy implications for COVID-19 response and future guidelines development. Methods: The contents of the COVID-19 IPC guidelines were analyzed using the categories and codes developed based on "World Health Organization guidelines on core components." Data analysis involved reviewing, appraising and synthesizing data from guidelines, which were then arranged into categories and codes. Selection of countries was based on the country income level, availability of COVID-19 specific IPC guideline developed at a national or district level. Results: The guidelines particularly agreed on IPC measures regarding application of standard precautions and providing information to patients and visitors, monitoring and audit of IPC activities and staff illnesses, and management of built environment/equipments. The guidelines showed considerable differences in certain components, such as workplace safety measures and criteria for discontinuation of precautions. Several guidelines also contained unique features which enabled a more systematic response to COVID-19. Conclusion: The guidelines generally complied with the current evidence-based COVID-19 management but also revealed variances stemming from differences in local health system capacity. Several unique features should be considered for benchmark in future guidelines development.

• Industry Promotion Research
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• v.7 no.4
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• pp.85-95
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• 2022

This study intends to analyze the meaning of symbolism in ancestral memorial rite arrangemen from the view that ancestral worship connecting traditional society with modernity are the transmission of ritual. It appears as a change the theory of Yin-Yang and Five Elements that became the basis and ideology about the Confucian view of life and death, an understanding of the universe structure, and a change in the four seasons. Ancestral memorial rite arrangements acknowledge the existence of ancestors. And it is understood as a ceremonial instrument which the living and the dead communicate spatially with time through the symbolic system. In addition, the four seasons, spaces of the skyground and underground were symbolized and embodied through the selection and arrangement of ancestral memorial rites. In the modern ancestral memorial rite arrangement, the factors that determine the location require Time-space analysis of the target. This is because the offering is understood not only as a functional role but also as a temporal and spatial symbolism to be expressed through the offering. In this study, it is meaningful to consider it from the perspective of inheritance of ancestral worship culture through discussions about the ideological background and symbolic system that appeared in ancestral memorial rite arrangement

• Journal of the Korea Institute of Information and Communication Engineering
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• v.26 no.7
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• pp.1026-1031
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• 2022

Cognitive Radio Ad-Hoc Networks (CRAHNs) enable to overcome the shortage of frequency resources due to the increase of radio services. In order to avoid interference with the primary user in CRANH, channel sensing to check the idle channel is required, and when the primary user appears, the time delay due to handover should be minimized through fast idle channel selection. In this paper, throughput was improved by reducing the number of channel sensing and preferentially sensing a channel with a high probability of being idle, using reinforcement learning. In addition, we proposed a multi-channel MAC (Medium Access Control) protocol that can minimize the possibility of collision with the primary user by sensing the channel at the time of data transmission without performing periodic sensing. The performance was compared and analyzed through computer simulation.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.23 no.5
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• pp.103-108
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• 2023

In this paper, a performance enhancement study of an AESA antenna that can be applied to a seeker that serves as the eye of a missile was conducted, and the performance of the antenna was verified through actual measurement. When designing an AESA antenna, the optimization of the active reflection coefficient must be considered during transmission due to the mutual coupling between radiators that inevitably occurs, and the selection of a radiator that can overcome the space limitation of the seeker with a small size/light weight is an important design consideration. Accordingly, optimization in terms of electrical performance and low-profile structure is required through research on array antennas for application to the AESA structure. The radiator designed and measured in this paper was designed as an SFN that can satisfy the low-profile structure while enhancing the performance of a general vivaldi antenna. Through this paper, it was confirmed that SFN has the same broadband characteristics as general vivaldi antennas and has optimized characteristics required for AESA antennas. The structure optimized through simulation confirmed the pattern characteristics and active reflection coefficient characteristics through the fabrication of actual proto-type antennas.