• Nuclear Engineering and Technology
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• v.54 no.8
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• pp.3117-3129
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• 2022

Deeply understanding the phase change of thin liquid sodium film inside wick pore is very important for further studying high-temperature sodium heat pipe's heat transfer. For the first time, the evaporation and condensation of thin liquid sodium film are investigated by the Lennard-Jones potential of molecular dynamics. Based on the startup and normal operation of the sodium heat pipe, three different cases are simulated. First, the equilibrium is achieved and the Mass Accommodation Coefficients of the three cases are 0.3886, 0.2119, 0.2615 respectively. Secondly, the non-equilibrium is built. The change of liquid film thickness, the number of gas atoms, the net evaporation flux (J_net), the heat transfer coefficient (h) at the liquid-gas interface are acquired. Results indicate that the magnitude of the J_net and the h increase with the basic equilibrium temperature. In 520-600 K (the startup of the heat pipe), the h has approached 5-6 W m^-2 K^-1 while liquid film thickness is in 11-13 nm. The fact shows that during the initial startup of the sodium heat pipe, the thermal resistance at the liquid-gas interface can't be negligible. This work is the complement and extension for macroscopic investigation of heat transfer inside sodium heat pipe. It can provide a reference for further numerical simulation and optimal design of the sodium heat pipe in the future.

• Journal of Dental Rehabilitation and Applied Science
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• v.38 no.2
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• pp.71-80
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• 2022

Although low translucency 3 mol% yttria stabilized tetragonal zirconia polycrystal has excellent mechanical properties, it has limited application as a monolithic prosthesis. To improve these optical limitations, translucent zirconia has improved esthetics due to an increase in the cubic phase; however, it is accompanied by a decrease in mechanical properties simultaneously. Lithium disilicate has improved its mechanical properties through crystal size reduction and various heat treatment methods; therefore, its clinical application range is continuously increasing. Translucent zirconia shows a wide distribution of physical properties depending on the yttria content and lithium disilicate according to the size and density of crystal grains. As a result, the indications for translucent zirconia and lithium disilicate are increasing. Therefore, in this literature review, we intend to examine the rationale behind the material selection criteria in clinical situations and considerations for designing fixed dental prostheses including pontic, in particular, by summarizing recent studies.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.34 no.6
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• pp.371-383
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• 2021

Steel-concrete single-leaf blast-resistant doors, having steel box and slab inside, are installed on the wall using supporting members such as hinges and latches. Several studies have been conducted on their deflection behavior in the same direction as that of the blast pressure, but studies on their deflection behavior in the opposite direction, that is, studies on negative deflection behavior are relatively insufficient. In this study, we conducted a parameter analysis using finite element analysis on blast-resistant doors, on their rebound behavior in the negative deflection phase. Results revealed that the plastic deformation of the door, and the change in momentum and kinetic energy during rebound, were major factors influencing the rebound behavior. Greater rebound force was developed on the supporting members in the impulsive region, than in the quasi-static region; due to the characteristics in the impulsive region, where the kinetic energy developed relatively greater than the strain energy. In the design process, it is necessary to consider excessive deformation that could occur in the supporting members as the rebound behavior progresses. Additionally, it was found that in the case of steel-concrete blast doors, the rebound force increased relatively more, when the effects of both rebound and negative blast pressure contributed to the negative deflection of the door. Since conditions for the occurrence of this superposition effect could vary depending on structural characteristics and explosion conditions, further investigation may be required on this topic.

• The Journal of the Korea Contents Association
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• v.22 no.3
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• pp.500-512
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• 2022

Post-Occupancy Evaluation (POE), which is one of the construction environment evaluation methods, is a series of processes that ask about the functional requirements and satisfaction of an object from a life cycle perspective such as design/construction/residence. However, there are no POE research activities targeting large-scale units. On the other hand, large-scale third-phase new towns are being developed. Therefore, this study conducted a post-residence evaluation (POE) research activity in a large-scale unit (Multifunctional Administrative City). The procedure of this study is to conduct a literature survey on the current status and implications of the multi-functional administrative city area, and based on the research data, derive the Happy City evaluation index for the major issues and special issues of the Happy City. Afterwards, 450 questionnaires were conducted for the residents of Happy City, and POE analysis was performed on the derived data for each module. And based on the analysis results, implications such as problems and improvement points for the current status of the Happy City were derived. This can be used as a basis for the expansion of a large-scale new city into a self-sufficient city, and it can be used as a basic data for the development and improvement of a happy city that meets social needs in the future.

• Journal of Environmental Impact Assessment
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• v.31 no.4
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• pp.201-213
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• 2022

Creation and administration of green space are emphasized to solve the environmental problem and the management of green space in urban area. Urban area with high development pressure faces green space fragmentation, so the planned approach is needed to improve the continuity of green space. However, the current institutional green axis, used to enhance continuity of urban space is merely an abstract concept under the master plan so that is not a consistent framework for urban green continuity providing no detailed information such as position and path. Therefore, in order to consistently manage green space in continuous point of view, it is insufficient not being connected to each individual green space development projects. This study proposes a method for finding the connection path to enhance urban green space continuity. This proposed method consists of two phases. First phase is finding nodes to connect current green space and second is to calculate the least cost path. We calculate connection cost using NDMI (Normalized Difference Moisture Index), impervious ratio and official land cost, applying to Suwon city and potential greening site that was planned in official master plan. According to the results, we confirm a possibility of finding a cost-effective connection path with detailed spatial information instead of unrealistic abstract concepts and discuss worth applying to a legally plan and policy.

• Journal of Appropriate Technology
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• v.7 no.2
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• pp.248-256
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• 2021

After the COVID-19 pandemic, hand hygiene has become more important to prevent and reduce infection. To manage and provide water to ensure safe handwashing, water governance and the role of public servants are also getting critical. Many organizations have given their priority to capacity building of public servants. In the Strategic Plan for the ninth phase of the Intergovernmental Hydrological Programme (2022-2029), 'Water education in the Fourth Industrial Revolution' is included as a priority. In Korea, ODA in the field of water and sanitation is emphasized in Korea's 3rd Mid-term Strategy for Development Cooperation (2021-2025). Also, KOICA and various water-related organizations have been organizing water education programs for developing countries. This study presents the direction for water education for public servants in developing countries in the post COVID-19 through the education program cases of the International Centre for Water Security and Sustainable Management established by the agreement between the Korean government and UNESCO in 2017. The study suggests that water-related organizations should cooperate with each other to prevent duplication of water education contents. It also suggests that blended learning should be actively utilized for the improvement of education program effectiveness. Lastly, the study emphasizes that education demand for the water technologies related to the fourth industrial revolution and smart water management is increasing, which should be considered when water-related organizations create online content or design education programs.

• Journal of the Korean Society of Marine Environment & Safety
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• v.27 no.7
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• pp.1124-1128
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• 2021

As regulations of emissions from ships become more stringent, electric propulsion systems have been increasingly used to solve this problem in vessels ranging from large merchant ships to small and medium-sized ships. Methods for improving the efficiency of the electric propulsion system include the improvement of power sources; the use of a system linked to environmentally friendly power sources, such as batteries, fuel cells, and solar power; and the development of hardware and control methodology for rectifiers, power conversion devices, and propulsion motors. The method using a phase-shifting transformer with diodes has been widely used for rectification. Power semiconductor devices with grid connection to an environmentally friendly power source using DC distribution, a variable speed power source, and the application of small and medium-sized electric propulsion systems have been developed. Accordingly, the demand for active front-end (AFE) rectifiers is increasing. In this study, a method using a neural network rather than a conventional proportional-integral controller was proposed to control the AFE rectifier. Tested controller data were used to design a neural network controller trained through MATLAB/Simulink. The neural network controller was applied to a rectification system designed using PSIM software. The results indicated the effectiveness of improving the waveform and power factor DC output stage according to the load variation. The proposed system can be applied as a rectification system for small and medium-sized environmentally friendly ships.

• Animal Bioscience
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• v.36 no.1
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• pp.119-131
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• 2023

Objective: This study was to assess the effects of different doses of an essential oil blend (EOB) on growth performance, diarrhea occurrence (DO), hematological and blood biochemical profile, intestinal morphometry, morphology and microbiology, relative weight and length of organs, digestive content pH, and liver antioxidant status in weaning piglets. Methods: A total of 135 barrows (7.09±0.29 kg body weight) were allotted randomly in a randomized complete block design based on body weight with nine replications and three animals per pen. Dietary treatments were a negative control (NC): basal diet; positive control (PC): NC plus 125 mg performance-enhancing antibiotic (enramycin 8%)/kg diet; NC plus 100 mg EOB/kg diet (EO100); NC plus 200 mg EOB/kg diet (EO200); and NC plus 400 mg EOB/kg diet (EO400). Diarrhea occurrence was monitored daily, and performance at the end of each phase. Results: Gain to feed ratio was greater (p<0.05) in starter II pigs fed EO400 and EO200 than in those fed EO100. Pigs fed EO400 had lower (p<0.05) DO than those fed NC and EO100 in the total period. Pre-starter II pigs fed NC had (p<0.05) lower serum total protein and plasma protein than pigs fed PC. Pigs fed EO100 showed smaller (p<0.05) mean corpuscular volume (MCV) than pigs fed EO400. Starter II pigs fed EO400 had (p<0.05) greater MCV and lower mean corpuscular hemoglobin and erythrocytes than those fed EO100. There was a greater concentration (p<0.05) of band cells for PC, similar to EO400 and EO200. Performance-enhancing antibiotic and EOB to diets increased (p<0.05) liver superoxide dismutase activity. Conclusion: Adding 200 and 400 mg EOB/kg diet decreased DO and was advantageous to hematological and blood biochemical profile and liver antioxidant status without being detrimental to growth performance and gastrointestinal health in nursery pigs.

• Journal of the Korea Society of Computer and Information
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• v.27 no.6
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• pp.131-137
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• 2022

As the age increases, the oral cavity, that is, the teeth and periodontium, also begin to age, and accordingly, a preparation process is required. The preparation process is an important period for oral health management to start continuously with oral health education consisting of knowledge, attitude, and behavior from the 20s. Therefore, to design a clinical dental hygiene course for patients who visited a dental clinic in Gyeonggi-do and received continuous care in an oral health care room after treatment, we tried to analyze the data of the dental hygiene assessment. As a dental hygiene assessment tool, based on personal information and general medical history, dental visit experience, bleeding on probing(BOP), bad breath measurement, phase contrast microscopy, and O'Leary index were performed. The number of subjects who had dental visits was 75.4% and those without experience were 24.6%, and as a result of the periodontal examination, generally bleeding was found in 76.3%. In preventive oral care, the stage of dental hygiene assessment in the 20s is an important first step. From this point on, it is an important time to be systematically habituated so that you can take responsibility for your own oral condition. Therefore, in this study, the results of dental hygiene assessment through oral examinations of subjects in their 20s are derived and presented as basic data for the development of dental hygiene performance competency of dental hygienists during the clinical dental hygiene process in oral health education and oral health management.

• Korean Journal of Forensic Psychology
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• v.12 no.1
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• pp.53-73
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• 2021

This study is an experimental study comparing the psycho-physiological response differences of subjects according to the rapport building in polygraph tests. We randomly assigned 84 adults into a 2(veracity: Truth vs. Lie) x 2(rapport; Rapport building vs. Non-rapport building) between-subject design and measured ESS total scores as psycho-physiological responses. In order to manipulate the veracity conditions, participants in the truthful condition were told to tell their actual scores on several simple tasks but those in the lie condition were asked to tell higher scores than their actual scores. Afterwards all participants were polygraph tested in the order of pre-interview and main examination. The rapport conditions were manipulated by structured pre-interview scripts. As a result, there were significant differences in the examinee's total ESS scores depending on the veracity and rapport conditions. For truth-tellers, the ESS total scores were greater in the positive(+) direction in the rapport building condition than in the non-rapport building condition, indicating a prominent true response in the former condition. For liars, however, the ESS total scores were not significantly greater in the negative(-) direction in the rapport building condition than in the non-rapport building condition. Based on this study's results, we discussed the importance of rapport building in the pre-interview phase of a polygraph test and the need to operationalize verbal and non-verbal rapport building techniques.