• Journal of Fisheries and Marine Sciences Education
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• v.16 no.2
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• pp.257-270
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• 2004

The two-phase closed thermosyphon is a heat transfer device capable of transfer large quantities of heat from a source to a sink by taking advantage of the high heat transfer rates associated with the evaporation and condensation of a working fluid within the device. A study was carried out with the performance of the heat transfer of the thermosyphon having 50, 60, 70, 80, 90 internal micro grooves in which boiling and condensation occur. A plain thermosyphon having the same inner and outer diameter as the grooved thermosyphon is also tested for comparison. Water, methanol and ethanol have been used as the working fluids. The liquid filling as the ratio of working fluid volume to total volume of thermosyphon, the inclination angle, micro grooves and operating temperature have been used as the experimental parameters. The heat flux and the boiling and the condensation heat transfer coefficient and overall heat transfer coefficient at the condenser and evaporator zone are estimated from the experimental results. The experimental results have been assessed and compared with existing correlations. Imura's and Kusuda's correlation for boiling showed in good agreement with experimental results within ${\pm}20$％ in plain thermosyphon. The maximum heat transfer rate was obtained when the liquid fill ratio was about 25%. The high heat transfer coefficient was found between 25o and 30o of inclination angle for water and between 20o and 25o for methanol and ethanol. The relatively high rates of heat transfer have been achieved in the thermosyphon with internal micro grooves. The micro grooved thermosyphon having 60 grooves shows the best heat transfer coefficient in both condensation and boiling. The maximum enhancement (i.e. the ratio of the heat transfer coefficients of the micro grooved thermosyphon to plain thermosyphon) is 2.5 for condensation and 2.3 for boiling.

• Journal of the Korean Geotechnical Society
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• v.37 no.10
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• pp.27-40
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• 2021

The construction method to prevent the frost heave or thaw settlement is called the ground stabilization method, and the thermo-syphon is one of the typical ground stabilization methods. The thermo-syphon has recently been developed with a simple analysis model and thermal analysis has been carried out, but the frost heave of frost susceptible soil was not considered. This study was conducted using ABAQUS internal user subroutine to develop the numerical analysis model (Coupled thermo-mechanical) that can simultaneously perform thermal analysis for the temperature change of the soil according to the thermo-syphon and structural analysis to predict the frost heave of the soil accordingly. As a result of the numerical analysis, the frost heave of the soil decreased as the performance of the thermo-syphon increased. As for the main results, when the thermo-syphon which has contain 25%, 50%, and 100% of refrigerant filling ratio was applied, the reduction ratio of the frost heave was 5.5%, 14.4%, and 21% respectively.

• Journal of The Korean Society of Grassland and Forage Science
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• v.39 no.2
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• pp.75-80
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• 2019

Oilseed rape is known to crop having low nitrogen use efficiency (NUE) but requires high levels of N fertilizer. NUE is associated with N remobilization from source to sink organ, consequently affects seed yield. Remobilization of leaf N is also related to transport of C/N metabolites in phloem. However, interaction between seed yield and phloem transport was not fully documented. In response to seed yield, N and C metabolites and their transport into seed from bolting to pod filling stage investigated in two contrasting genotypes (Capitol and Pollen) cultivated under ample (HN) or limiting nitrate (LN) supply. Seed yield was significantly reduced in N limitation and its reduction rate was much lower in Capitol than in Pollen compared to HN treated plants. Amino acid and protein content was higher in Capitol than in Pollen at bolting stage. They gradually decreased during plant development but not significant between two cultivars and/or two treatments. Glucose, fructose and sucrose content were 1.8-,1.6- or 1.25-fold higher in LN condition than in HN condition, respectively. Amino acid and sucrose content in phloem were largely higher in Capitol than in Pollen under LN condition. These results indicate that the higher seed yield might be related to greater transport ability of amino acid and sucrose in phloem under LN condition.

• Archives of Craniofacial Surgery
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• v.20 no.3
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• pp.176-180
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• 2019

Background: Parotidectomy is the treatment of choice in many parotid tumors. Due to the extensive nature of the procedure, unfavorable complications such as gustatory sweating, surgical site depression are common. Various techniques using fascia, muscle or AlloDerm have been developed but debate still remains regarding its availability and affordability. We applied a newly developed acellular dermal matrix (Insuregraf) to the parotidectomy field to act as a physical barrier and to provide adequate filling effect for prevention of functional and aesthetic complications. Methods: From March 2010 to March 2017, 30 patients with parotid tumors underwent superficial parotidectomy. Twenty patients underwent only superficial parotidectomy. Ten patients had Insuregraf applied to the surgical site after superficial parotidectomy. We evaluated the incidence of Frey's syndrome, surgical site depression, and patient satisfaction rate in both groups. Results: The incidence of Frey's syndrome was lower in the Insuregraf group (0 vs. 2). Surgical site depression was also lower in the Insuregraf group (2 vs. 20). Satisfaction score for facial contour in Insuregraf group was 9.2 out of 10, which was comparable to 6.2 out of 10 in the control group. Conclusion: Application of Insuregraf after superficial parotidectomy is an effective surgical procedure to prevent complications such as Frey's syndrome and surgical site depression. This technique is affordable and safe with no immune reactions. Above all this surgical method should be considered as an option for patients who are concerned about the contour of the face after surgery.

• Clinical and Molecular Hepatology
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• v.24 no.4
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• pp.409-416
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• 2018

Background/Aims: Left ventricular diastolic dysfunction (LVDD) is an early manifestation of cardiac dysfunction in patients with liver cirrhosis (LC). However, the effect of LVDD on survival has not been clarified, especially in decompensated LC. Methods: We prospectively enrolled 70 patients with decompensated LC, including ascites or variceal bleeding, at Daejeon St. Mary's Hospital from April 2013 to April 2015. The cardiac function of these patients was evaluated using 2D echocardiography with tissue Doppler imaging. The diagnosis of LVDD was based on the American Society of Echocardiography guidelines. The primary endpoint was overall survival. Results: Forty-four patients (62.9%) had LVDD. During follow-up (22.3 months), 18 patients died (16 with LVDD and 2 without LVDD). The survival rate was significantly lower in patients with LVDD than in those without LVDD (31.1 months vs. 42.6 months, P=0.01). In a multivariate analysis, the Child-Pugh score and LVDD were independent predictors of survival. Moreover, patients with a ratio of early filling velocity to early diastolic mitral annular velocity (E/e') ${\geq}10$ (LVDD grade 2) had lower survival than patients with E/e' ratio < 10. Conclusions: The presence of LVDD is associated with poor survival in patients with decompensated LC. Therefore, it may be important to monitor and closely follow LVDD patients.

• Journal of dental hygiene science
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• v.21 no.4
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• pp.243-250
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• 2021

Background: Endodontic sealers or their toxic components may become inflamed and lead to delayed wound healing when in direct contact with periapical tissues over an extended period. Moreover, an overfilled sealer can directly interact with adjacent tissues and may cause immediate necrosis or further resorption. Therefore, the treatment outcome conceivably depends on the endodontic sealer's biocompatibility and osteogenic potential. This study aimed to evaluate the cell viability and osteogenic effects of four different sealers in osteoblastic cells. Methods: AH Plus (resin-based sealer), Pulp Canal Sealer EWT (zinc oxide-eugenol sealer), BioRoot RCS (calcium silicate-based sealer), and Well-Root ST (MTA-based calcium silicate sealer) were mixed strictly according to the manufacturer's instructions, and dilutions of sealer extracts (1/2, 1/5 and 1/10) were determined. Cell viability was measured using the water-soluble tetrazolium-8 (WST-8) assay. Differentiation was assessed by alkaline phosphatase (ALP) activity and mineralized nodule formation by Alizarin Red S staining. Results: The cell viability of the extracts derived from the sealers excluding Well-Root ST was concentration dependent, with sealer extracts having the least viability at a 1/2 dilution. At sealer extract dilution of 1/10, the test groups showed the same survival rate as that control group, with the exception of BioRoot RCS. Among all experimental groups, BioRoot RCS showed the highest cell viability after 48 hours. The ALP activity was significantly higher in a concentration-dependent manner. Furthemore, all four materials promoted ALP activity and mineralized nodule formation compared to the control at 1/10 dilutions. Conclusion: This is the first study to highlight the differences in biological activity of these four materials. These results suggest that the composition of root canal sealers appears to alter the form of biocompatibility and osteoblastic differentiation.

• Transactions of the Korean hydrogen and new energy society
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• v.35 no.3
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• pp.280-289
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• 2024

In this study, a cryogenic vessel was constructed to maintain and control the safe pressure of liquid hydrogen boil-off gas (BOG), and the numerical analysis was conducted on the development of computational fluid dynamics model inside the high-pressure vessel. An evaluation system was constructed using cryogenic inner and outer containers, pre-cooler, upper flange, and internal high-pressure container. We attempted to analyze the performance of the safety valve by injecting relatively high temperature hydrogen gas to generate BOG gas and quickly control the pressure of the high-pressure vessel up to 10 bar. As a results, the liquid volume fraction decreased with a rapid evaporation, and the pressure distribution increased monotonically inside a high pressure vessel. Additionally, it was found that the time to reach 10 bar was greatly affected by the filling rate of liquid hydrogen.

• Journal of Platform Technology
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• v.11 no.6
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• pp.34-46
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• 2023

The design of non-pneumatic tires, which are created by filling the space between the wheel and the tread with elastomeric compounds or polygonal spokes, has become an important research topic in the automotive and aerospace industries. In this study, a system was designed for the design of non-pneumatic tires through the implementation of a generative adversarial network. We specifically examined factors that could impact the design, including the type of non-pneumatic tire, its intended usage environment, manufacturing techniques, distinctions from pneumatic tires, and how spoke design affects load distribution. Using OpenCV, various shapes and spoke configurations were generated as images, and a GAN model was trained on the projected GANs to generate shapes and spokes for non-pneumatic tire designs. The designed non-pneumatic tires were labeled as available or not, and a Vision Transformer image classification AI model was trained on these labels for classification purposes. Evaluation of the classification model show convergence to a near-zero loss and a 99% accuracy rate confirming the generation of non-pneumatic tire designs.

• Journal of the Korea institute for structural maintenance and inspection
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• v.11 no.4
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• pp.89-98
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• 2007

The purpose of this study is to experimentally evaluate the structural behavior of built-up type column consisted of angles and y-shape steel sheet forms for filling concrete. This column for minimizing form working and reinforcement placing is able to improve capacity of construction and reduce the term of works. Thirteen 1/3 scaled columns were fabricated. The main variables are 1) effect of angles and y-shape steel sheets of fabricated columns, 2) slenderness of column, 3) eccentricity of column. The results show that the experimental capacity of built-up type column is similar to theoretical one by reinforcement concrete design code. The maximum loads increase according to the rate of angle to cross section of column.

• Journal of the korean academy of Pediatric Dentistry
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• v.49 no.3
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• pp.285-299
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• 2022

The aim of this study is to investigate the awareness and perception of pediatric dentists regarding dental health insurance (DHI) system in Korea. Online surveys were sent to the members of the Korean Academy of Pediatric Dentistry (KAPD), and the responses were collected. The survey, consisting of 41 questions, was subdivided into 'general background of the respondents', 'the awareness on national health insurance (NHI) and DHI', 'the awareness on DHI pertaining to pediatric dentistry', 'issues that need improvement on DHI pertaining to pediatric dentistry', 'DHI claims', and 'the roles of KAPD in DHI'. In total, 302 responded, with a response rate of 28.9%. Excluding 2 questionnaires with insufficient answers, a total of 300 survey results were analyzed. According to the analysis, pediatric dentists thought that the coverage of DHI was not as sufficient compared to that of NHI, but were expecting its scope to broaden in the future. The satisfaction rate was higher in pit and fissure sealant and composite resin filling than in caries-detecting quantitative light-induced fluorescence. Pediatric dentists considered permanent tooth composite resin filling (65.7%) needed an increase in insurance copayment, while topical fluoride application (74.7%) to require insurance coverage. DHI claims were generally handled by dental hygienists and/or nursing assistants. Approximately half of the respondents answered that they have had experiences on appealing for insurance denials. Lastly, pediatric dentists generally had a positive attitude towards providing information for the DHI. This study is expected to be used as a sound dataset for the DHI policy development concerning pediatric dentistry.