• Nuclear Engineering and Technology
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• 제54권9호
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• pp.3540-3550
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• 2022

The supercritical carbon dioxide (S-CO₂) Brayton cycle is an important energy conversion technology for the fourth generation of nuclear energy. Since the printed circuit heat exchanger (PCHE) used in the S-CO₂ Brayton cycle has narrow channels, Rayleigh-Bénard (RB) convection is likely to exist in the tiny channels. However, there are very few studies on RB convection in supercritical fluids. Current research on RB convection mainly focuses on conventional fluids such as water and air that meet the Boussinesq assumption. It is necessary to study non-Boussinesq fluids. PRB convection refers to RB convection that is affected by horizontal incoming flow. In this paper, the computational fluid dynamics simulation method is used to study the PRB convection phenomenon of non-Boussinesq fluid-supercritical carbon dioxide. The result shows that the inlet Reynolds number (Re) of the horizontal incoming flow significantly affects the PRB convection. When the inlet Re remains unchanged, with the increase of Rayleigh number (Ra), the steady-state convective pattern of the fluid layer is shown in order: horizontal flow, local traveling wave, traveling wave convection. If Ra remains unchanged, as the inlet Re increases, three convection patterns of traveling wave convection, local traveling wave, and horizontal flow will appear in sequence. To characterize the relationship between traveling wave convection and horizontal incoming flow, this paper proposes the relationship between critical Reynolds number and relative Rayleigh number (r).

• 환경영향평가
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• 제17권5호
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• pp.263-270
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• 2008

The purpose of this study was to investigate the characteristics of the temple wastes and suggest the waste management guidelines for temples in natural parks. Study results revealed four important findings. First, it was found that the average quantity of the total temple wastes was 85,786g/day which was composed of general wastes(44,617g/day), food wastes(20,292g/day), recycling wastes(20.825g/day), and buddhist service wastes(60g/day). The average generation per capita of the temple wastes was 1,511g/capita day and the average bulk density was 0.102kg/l. Second, the food scrap was of small quantity(72.5g/day) because the traditional buddhist eating method, "Baru meal(鉢盂供養)" prohibits food abuse. This amount is very little compared to that produced in the general household in Korea. Third, the average quantity of the buddhist service wastes was 300-1,650g/one time. This wastes occupied 0.07% of the total temple wastes. Fourth, the average waste generated by visitors was 182.8g/person, which occupied 87.1% of the total temple wastes and costed 52,100,000 Wons to treat.

• Restorative Dentistry and Endodontics
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• 제18권2호
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• pp.483-496
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• 1993

Dentin hypersensitivity medicaments such as Gluma, Scotchbond 2, All-Bond 2, which are resin adhesives, were used to compare the sealing effects of dentinal tubule under mechanical stress. Topical application of above medicaments on the dentin surfaces of extracted teeth followed by artificial tooth brushing for 6 weeks was performed for the comparison. The following conclusions on the degree of dentinal tubule exposure versus time by were reached by using polyvinyl siloxane impression material for taking the impression, epoxy resin for the duplication and SEM for observing the surface. 1. SEM was used to compare the accuracy of the duplicated surface, but no differences were found when teeth samples and the duplicated surfaces were observed. 2. After comparing the degree of dentinal tubules exposure with varnish applied contrast group, resin adhesive materials showed much less exposure as time went by. 3. The results indicated that AU-Bond 2 adhesive, under mechanical stress, showed lesser exposure of dentinal tubules comparing with Gluma and Scotchbond 2 adhesives After the results were put together, it was demonstrated that resin replica method is an useful way to evaluate the treatment effects of the dentinal tubule hypersensitivity medicaments. Also, it was noticed that under mechanical stress, All-Bond 2, classified as fourth generation, illustrated the best dentinal tubules sealing effects.

• 가정과삶의질연구
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• 제21권4호
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• pp.79-92
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• 2003

This research aims to verify the generation transfer of proper manners from mothers to adolescent children and the relationship between adolescents' proper manners and strengths of family life. The data from 826 questionnaires (413 pairs of adolescents and mothers) were used for the final analysis. The findings of the study are summarized as follows: First, as for the extent of the implementation of manners of mothers and adolescent children both parties generally abided by good manners, but a significant difference emerged in the patterns. Second, both mothers and adolescent children were influenced by psychological determinants of self-esteem, values of humanism, emotional intimacy between mother and child, and social support for the implementation of good manners. On the other hand, adolescent children were affected the most by the emotional intimacy with mothers. Third, children generally showed significant differences in their implementation of manners according to the manners their mothers. Fourth, there were significant differences in the strengths of family life for adolescent children depending on their implementation of manners. Fifth, when comparing the relative contribution of the mothers' psychological determinants on strengths of family life and adolescent children's psychological determinants on the implementation of manners, strengths of family life gained more credibility as more variables were added.

• 복식문화연구
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• 제3권2호
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• pp.371-391
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• 1995

This study is to infer consumer's value and demographics towards Missy, who are womens of new generation which represents new consumer group in fashion industry. The concrete purpose of the study is as follows : First : To find out the differences of value inference towards Missy depending on demographics of researched group. Second : To find out differences of value inference towards Missy depending on self-evaluation. Third : To find out differences of perception towards Missy's demographics between the groups of career women, housewives, students. Fouth : To find out differences of perception towards Missy's demographics depending on self-evaluation about Missy's of researched group. The researched group was 251 women aged between $20\sim30$ living in Seoul and sample have been selected from various profession. Method of the study was by using questionnares which were based on results of pretest and preceding research. Analysis of the study was achieved by using SPSS package which are frequency, percentage, $x^2$-test, t-test and Anova, Duncan-test and the results are as follows: First : There are significant differences of value inference towards Missy between the groups who are perceived themselves Missy by self evaluation and the groups who are not. Third : There are significant differences of perception towards Missy's demographics between the groups of career women, housewives, students. Fourth : There are significant differences of perception in regards to Missy's demographics between perceived themselves Missy and the others who are not.

• Journal of Communications and Networks
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• 제7권2호
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• pp.178-191
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• 2005

Fourth-generation (4G) wireless networks will be the IP-based cellular networks integrating Internet with the existing cellular networks. Two important issues should be concerned in the IP-based cellular networks, IP mobility, and quality-of-service (QoS) guarantees. In this paper, we proposed two mechanisms to solve the problems with IP mobility and RSVP-based QoS provisioning. First, virtual-IP (VIP) allocation scheme in areas with a large rate of handoff can minimize the wireless signaling overhead due to IP mobility. The access routers (ARs) create dynamically the VIP zone by using the measured handoff rate derived from the history of the handoff into neighboring ARs. We show that VIP allocation scheme reduces the binding update messages in the wireless link than hierarchical mobile IPv6. Second, the new advance resource reservation protocol called proportional aggregate RSVP (PA-RSVP) can minimize waste of bandwidth and soft state refresh overhead due to IP mobility. It allocates the bandwidth in advance between the mobility anchor point and neighboring ARs using proportional aggregate reservation. We also show that PA-RSVP provides an improved performance over existing protocols.

• 한국전기전자재료학회논문지
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• 제36권6호
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• pp.620-626
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• 2023

Energy harvesting technology, which converts wasted energy sources in everyday life into usable electric energy, is gaining attention as a solution to the challenges of charging and managing batteries for the driving of IoT sensors, which are one of the key technologies in the era of the fourth industrial revolution. Hybrid energy harvesting technology involves integrating two or more energy harvesting technologies to generate electric energy from multiple energy conversion mechanisms. In this study, a hybrid energy harvesting device called TMPPEG (thermo-magneto-piezoelectric-pyroelectric energy generator), which utilizes low-grade waste heat, was developed by incorporating PVDF polymer piezoelectric components and optimizing the system. The variations in piezoelectric output and thermoelectric output were examined based on the spacing of the clamps, and it was found that the device exhibited the highest energy output when the clamp spacing was 2 mm. The voltage and energy output characteristics of the TMPPEG were evaluated, demonstrating its potential as an efficient hybrid energy harvesting component that effectively harnesses low-grade waste heat.

• 한국의상디자인학회지
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• 제25권2호
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• pp.31-44
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• 2023

Fashion design in the metaverse is not simply a 3D avatar or virtual fashion, it is an important clue for shopping trends, and the role of fashion design has grown even more because avatars and humans are identified and active. This study, I attempts to understand the metaverse platform accurately and find out the scope of fashion design within the metaverse platform. In addition, we want to provide basic data that can expand the field by using fashion design in various ways on the metabus platform. This study investigated and analyzed various metaverse fashion cases, articles, software, and methods used by metaverse fashion creators, and the results are as follows. First, the metaverse platform is a new level of virtual interaction where users and creators communicate through the convergence of augmented reality, lifelogging, mirror world, and virtual world. Second, most of the users of the metaverse platform are generation Z, and metaverse creators who make money by producing avatars or items, including fashion design, are emerging as a new job field. Third, many fashion brands created spaces on the Metaverse platform, collaborated with games, or opened fashion weeks for publicity, marketing, and sales. Fourth, as a 3D program for metaverse fashion creator activities, open-source software is easier and free of charge compared to programs for fashion design specialists, and most costumes can be reproduced, so it will be easier for fashion design majors to utilize.

• 한국멀티미디어학회논문지
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• 제22권2호
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• pp.194-202
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• 2019

In the information society represented by the Fourth Industrial Revolution, various types of data and information that are difficult to see are produced, processed, and processed and circulated to enhance the value of existing goods. The IoT(Internet of Things) paradigm will change the appearance of individual life, industry, disaster, safety and public service fields. In order to implement the IoT paradigm, several elements of technology are required. It is necessary that these various elements are efficiently connected to constitute one system as a whole. It is also necessary to collect, provide, transmit, store and analyze IoT data for implementation of IoT platform. We designed and implemented a big data processing IoT platform for IoT service implementation. Proposed platform system is consist of IoT sensing/control device, IoT message protocol, unstructured data server and big data analysis components. For platform testing, fixed IoT devices were implemented as solar power generation modules and mobile IoT devices as modules for table tennis stroke data measurement. The transmission part uses the HTTP and the CoAP, which are based on the Internet. The data server is composed of Hadoop and the big data is analyzed using R. Through the emprical test using fixed and mobile IoT devices we confirmed that proposed IoT platform system normally process and operate big data.

• ETRI Journal
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• 제40권3호
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• pp.309-317
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• 2018

Single carrier-frequency-division multiple access (SC-FDMA) has been adopted as the uplink transmission standard in fourth-generation cellular networks to facilitate power efficiency transmission in mobile stations. Because multiuser multiple-input multiple-output (MU-MIMO) is a promising technology employed to fully exploit the channel capacity in mobile radio networks, this study investigates the uplink transmission of MU-MIMO SC-FDMA systems with orthogonal space-frequency block codes (SFBCs). It is preferable to minimize the length of the cyclic prefix (CP). In this study, the chained turbo equalization technique with chained turbo estimation is employed in the designed receiver. Chained turbo estimation employs a short training sequence to improve the spectrum efficiency without compromising the estimation accuracy. In this paper, we propose a novel and spectrally efficient iterative joint-channel estimation, multiuser detection, and turbo equalization for an MU-MIMO SC-FDMA system without CP-insertion and with short TR. Some simulation examples are presented for the uplink scenario to demonstrate the effectiveness of the proposed scheme.