• Nuclear Engineering and Technology
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• 제51권4호
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• pp.1008-1016
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• 2019

In the SG (steam generator) of PWR (pressurized water reactor) for a nuclear plant, hundreds of U-shaped tubes are used for the heat exchanger system. They interact with primary pressurized cooling water flow, generating flow-induced vibration in the secondary flow region. A simplified U-tube model is proposed in this study to apply for experiment and its counterpart computation. Using the commercial code, ANSYS-CFX, we first verified the Moody chart, comparing the straight pipe theory with the results derived from CFD (computational fluid dynamics) analysis. Considering the virtual mass of fluid, we computed the major modes with the low natural frequencies through the comparison with impact hammer test, and then investigated the effect of pump flow in the frequency domain using FFT (fast Fourier transform) analysis of the experimental data. Using two-way fluid-structure interaction module in the CFD code, we studied the influence on mean flow rate to generate the displacement data. A feasible CFD method has been setup in this research that could be applied potentially in the field of nuclear thermal-hydraulics.

• 방사성폐기물학회지
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• 제19권2호
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• pp.225-231
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• 2021

The reaction between Li₂CO₃ and Cl₂ was investigated to verify its occurrence during a carbon-anode-based oxide reduction (OR) process. The reaction temperature was identified as a key factor that determines the reaction rate and maximum conversion ratio. It was found that the reaction should be conducted at or above 500℃ to convert more than 90% of the Li₂CO₃ to LiCl. Experiments conducted at various total flow rate (Q) / initial sample weight (W_i) ratios revealed that the reaction rate was controlled by the Cl₂ mass transfer under the experimental conditions adopted in this work. A linear increase in the progress of reaction with an increase in Cl₂ partial pressure (pCl₂) was observed in the pCl₂ region of 2.03-10.1 kPa for a constant Q of 100 mL·min^-1 and W_i of 1.00 g. The results of this study indicate that the reaction between Li₂CO₃ and Cl₂ is fast at 650℃ and the reaction is feasible during the OR process.

• The Journal of Asian Finance, Economics and Business
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• 제8권2호
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• pp.1169-1179
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• 2021

This research aims to develop the instrument of feasible and reliable digital-age literacy to be used in the learning process. This needs to be done due to a different region, tribe, and gender involved in this research. The digital-age literacy developed in this research consisting of 8 constructs, including 1) basic literacy, 2) scientific skill, 3) economy skill, 4) information skill, 5) technology skill, 6) visual skill, 7) various cultures skill, and 8) global awareness. As many as 650 respondents were chosen through stratified and random sampling in this survey. Those respondents were students at Universitas Terbuka based on gender and Ethnicity comparison. To see the internal consistency, the data were then analyzed using SPSS 23.00 version for Windows. It was obtained that all questionnaire constructs were valid and reliable, proven by obtaining a high mean reliability value of Cronbach Alpha (0.816 > 0.6), in which each item had a high value (0.778-0.841). Therefore, the number obtained the results proved that this research had produced a quality instrument that can be used to evaluate the students' mastery of the digital-age literacy of the learning process in Universitas Terbukain Asia, especially in Indonesia.

• 한국도서관정보학회지
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• 제51권4호
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• pp.333-349
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• 2020

이 연구는 공공도서관 지역특성화장서 구축의 필요성과 구축 방법론에 대하여 논하고 있다. 지역과 지역 문화의 정체성을 제고하고 지역사회의 기억을 유지·보존하기 위해서 지역특성화자료(향토자료)를 수집, 보존, 제공하는 것은 공공도서관의 중요한 책무 중 하나이다. 그러나 지역특성화자료는 주제와 유형이 다양하고 지역사회 내 다양한 주체들에 의해 소유되고 산재되어 있어서, 자료의 수집과 장서 구축에 어려움이 많으며, 도서관 현장의 혼선도 적지 않다. 이에 따라 이 연구에서는 지역특성화장서를 구축하고 있는 공공도서관 몇 곳의 사례를 중심으로 지역의 역사와 로컬리티를 담은 지역특성화장서를 구축하고 관련 서비스를 활성화하기 위한 방법론을 제안하고자 하였다.

• 한국기계가공학회지
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• 제20권1호
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• pp.16-24
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• 2021

A laser-engineered net shaping (LENS) process is a representative directed energy deposition process. Deposition characteristics of the LENS process are greatly dependent on the process parameters. The present paper preliminarily investigates deposition characteristics of Inconel 718 superalloy on S45C structural steel using a LENS process. The influence of process parameters, including the laser power and powder feed rate, on the characteristics of the bead formation and the dilution in the vicinity of the deposited region is examined through repeated experiments. A processing map and feasible deposition conditions are estimated from viewpoints of the aspect ratio, defect formation, and the dilution rate of the deposited bead. Finally, an appropriate deposition condition considering side angle, deposition ratio, and buy-to-fly (BTF) is predicted.

• 한국동물생명공학회지
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• 제35권4호
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• pp.323-328
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• 2020

Direct injection of genome editing tools such as CRISPR/Cas9 system into developing embryos has been widely used to generate genetically engineered pigs. The approach allows us to produce pigs carrying targeted modifications at high efficiency without having to apply somatic cell nuclear transfer. However, the targeted modifications during embryogenesis often result in mosaicism, which causes issues in phenotyping founder animals and establishing a group of pigs carrying intended modifications. This study was aimed to establish a genomic PCR and sequencing system of a single blastomere in the four-cell embryos to detect potential mosaicism. We performed genomic PCR in four individual blastomeres from four-cell embryos. We successfully amplified target genomic region from single blastomeres of 4-cell stage embryo by PCR. Sanger sequencing of the PCR amplicons obtained from the blastomeres suggested that PCR-based genotyping of single blastomere was a feasible method to determine mutation type generated by genome editing technology such as CRISPR/Cas9 in early stage embryos. In conclusion, we successfully genotyped single blastomeres in a single 4-cell stage embryo to detect potential mosaicism in porcine embryos. Our approach offers a simple platform that can be used to screen the prevalence of mosaicism from designed CRISPR/Cas9 systems.

• 한국기계가공학회지
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• 제21권2호
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• pp.87-93
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• 2022

The demand for metal-polymer joining technology have been increasing, especially in the industrial fields of automotive and aerospace, which require the manufacturing of various lightweight parts. Conventional joining processes have technical hurdles on aspects such as thermal degradation, need for chemical surface treatment, or complicated process settings. These issues can be alleviated by employing interlocking structures for the metal-polymer joined interface. In this study, we joined 3D-printed metal and polymer parts, which were featured with 3D-printed interlocking structures at their interface. By using high frequency induction heating, the joined region could be locally heated to reduce the thermal degradation and distortion of polymer parts. In addition, through the adjustment of interface morphologies and compression conditions, the polymer flow could be optimized to completely fill the interlocking grooves on metal parts, thereby achieving high joining strength. This suggests feasible guidelines for manufacturing metal-polymer joined structures involving 3D-printed architectures.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제16권8호
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• pp.2648-2665
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• 2022

Device-to-device (D2D) multicast has become a promising technology to provide specific services within a small geographical region with a high data rate, low delay and low energy consumption. However, D2D multicast communications are allowed to reuse the same channels with cellular uplinks and result in mutual interference in a cell. In this paper, an intelligent channel assignment algorithm is designed in D2D underlaid cellular networks with the target of maximizing network throughput. We first model the channel assignment problem to be a throughput maximizing problem which is NP-hard. To solve the problem in a feasible way, a novel channel assignment algorithm is proposed. The key idea is to find the appropriate cellular communications and D2D multicast groups to share a channel without causing critical interference, i.e., finding a channel for a D2D multicast group which generates the least interference to network based on current channel assignment status. In order to show the efficacy and effectiveness of our proposed algorithm, a novel search algorithm is proposed to find the near-optimal solution as the baseline for comparisons. Simulation results show that the proposed algorithm improves the network throughput.

• 로봇학회논문지
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• 제18권1호
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• pp.10-17
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• 2023

Recently, robots have been actively utilized for logistics and delivery services in various places such as restaurants, hotels, and hospitals. In addition, it provides a safer environment, convenience, and cost efficiency to the customers. However, when it comes to autonomous delivery in a multi-floor environment, the task is still challenging. Especially for wheeled mobile robots, it is necessary to deal with elevators to perform the last-mile delivery services. Therefore, we present a multi-floor route planning algorithm that enables a wheeled mobile robot to traverse an elevator for the delivery service. In addition, an elevator boarding mission algorithm was developed to perceive the drivable region within the elevator and generate a feasible path that is collision-free. The algorithm was tested with real-world experiments and was demonstrated to perform autonomous postal delivery service in a multi-floor building. We concluded that our study could contribute to building a stable autonomous driving robot system for a multi-floor environment.

• 한국조경학회지
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• 제37권3호
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• pp.82-90
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• 2009

이 연구는 농촌마을의 경관계획을 실행하는데 있어 필요한 경관기초단위 도출을 목적으로 진행되었다. 지금까지 다양한 농촌공간의 경관단위 및 경관 요소에 관한 연구들이 진행되어 오고 있지만 실질적인 계획적 측면에서 농촌지역 경관계획을 수립하는데 농촌마을단위의 경관적 정체성을 반영하는데는 그 한계가 있었다. 우리나라 농촌지역의 경관에 관한 계획적 접근은 농업과 주거단위를 통합적으로 접근하는 농촌경관계획과 주거지를 대상으로 하는 마을경관계획으로 크게 구분할 수 있다. 본 연구는 농촌마을 종합개발사업의 한 부분으로 실행되고 있는 경관계획에 마을경관이 가지고 있는 경관 정체성을 반영하고 이를 통하여 마을경관이 가지고 있는 경관적 정체성을 확보하며, 나아가 농촌 경관계획이 보다 현실적 측면에서 실행될 수 있는 방안을 도출하고자 하였다. 연구의 대상지역인 완도군 약산면을 자연적 특성에 기초하여 1:5000 지형도를 이용한 수계단위별 시각적 한계 분석을 실시하고, 분석 결과를 기초로 마을 경관의 가시영역 경계를 설정하였으며, 가시영역안의 경관이 하나의 정체성을 가지고 있는지를 농촌 어메니티자원 분류에 의한 경관자원요소들을 대상으로 현장조사를 실시하였다. 최종적으로 현장조사결과와 가시영역과의 경관적 정체성이 일치하는지에 대한 비교 분석을 통해 마을경관단위를 확정한 후 그 특성을 도출하였다. 현재 여러 지역에서 농촌마을 종합개발사업을 시행하고 있으며, 지역적 특성을 반영하기 위한 다양한 계획기법이 시도되고 있다. 이러한 시점에서 본 연구는 농촌경관의 기초가 되는 마을경관의 정체성을 유지할 수 있는 계획기법을 제안하고자 하였으며, 향후 지역경관계획으로 발전하기 위한 기초연구로 활용될 수 있을 것으로 사료된다.