• Korean Journal of Dental Materials
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• v.44 no.4
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• pp.329-336
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• 2017

This study evaluates the machining accuracy of the custom abutment design according to the selected convergence angle and radius of curvature value in the CAD program. Ten custom abutments were designed based on dental CAD. And then, the fabricated custom abutment was scanned ten times using a contact scanner. The data of the scanned custom abutment was saved as "Test STL" file. The Geomagic studio software was used to superposition each exported as an "Test STL" file with the CAD-reference-model STL file (CRM) specified by the same name. In the experimental results, the A8 group (convergence angle $8^{\circ}$) showed lower error than the A4 group (convergence angle $4^{\circ}$) . In addition, the higher the radius of curvature, the less error in the top and chamfer regions of the custom abutment (p< 0.05). Overall, the convergence angle and radius of curvature value in the custom abutment design were found to affect the machining accuracy.

• Nuclear Engineering and Technology
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• v.56 no.3
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• pp.803-811
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• 2024

Nuclear accidents such as Fukushima Daiichi have highlighted the potential of passive safety systems to replace or complement active safety systems as part of the overall prevention and/or mitigation strategies. In addition, passive systems are key features of Small Modular Reactors (SMRs), for which they are becoming almost unavoidable and are part of the basic design of many reactors available in today's nuclear market. Nevertheless, their potential to significantly increase the safety of nuclear power plants still needs to be strengthened, in particular the ability of computer codes to determine their performance and reliability in industrial applications and support the safety demonstration. The PASTELS project (September 2020-February 2024), funded by the European Commission "Euratom H2020" programme, is devoted to the study of passive systems relying on natural circulation. The project focuses on two types, namely the SAfety COndenser (SACO) for the evacuation of the core residual power and the Containment Wall Condenser (CWC) for the reduction of heat and pressure in the containment vessel in case of accident. A specific design for each of these systems is being investigated in the project. Firstly, a straight vertical pool type of SACO has been implemented on the Framatome's PKL loop at Erlangen. It represents a tube bundle type heat exchanger that transfers heat from the secondary circuit to the water pool in which it is immersed by condensing the vapour generated in the steam generator. Secondly, the project relies on the CWC installed on the PASI test loop at LUT University in Finland. This facility reproduces the thermal-hydraulic behaviour of a Passive Containment Cooling System (PCCS) mainly composed of a CWC, a heat exchanger in the containment vessel connected to a water tank at atmospheric pressure outside the vessel which represents the ultimate heat sink. Several activities are carried out within the framework of the project. Different tests are conducted on these integral test facilities to produce new and relevant experimental data allowing to better characterize the physical behaviours and the performances of these systems for various thermo-hydraulic conditions. These test programmes are simulated by different codes acting at different scales, mainly system and CFD codes. New "system/CFD" coupling approaches are also considered to evaluate their potential to benefit both from the accuracy of CFD in regions where local 3D effects are dominant and system codes whose computational speed, robustness and general level of physical validation are particularly appreciated in industrial studies. In parallel, the project includes the study of single and two-phase natural circulation loops through a bibliographical study and the simulations of the PERSEO and HERO-2 experimental facilities. After a synthetic presentation of the project and its objectives, this article provides the reader with findings related to the physical analysis of the test results obtained on the PKL and PASI installations as well an overall evaluation of the capability of the different numerical tools to simulate passive systems.

• Journal of Korean social welfare administration
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• v.20 no.3
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• pp.161-184
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• 2018

This is a following study of Choi et al.(2017) which developed and evaluated the psychological self-sufficiency program I. Psychological self-sufficiency program I(PSSI) reported the positive effectiveness in employment hope, self-efficacy, self-esteem, and depression among participants. PSSI, however, revealed limitations such as service provider-oriented practice and rapid decrease of program effectiveness after finishing program. The current study proposes psychological self-sufficiency program II(PSSII) revised to make up for the limitations found in PSSI by revising the contents and operation methods of PSSI. The study assessed program effectiveness using two different methods: 1) experimental group pre-test post-test design and 2) pre-test post-test design on the experimental group and control group. The study results report the effectiveness of PSSII in improving psychological self-sufficiency(i.e., employment hope and perceived employment barrier), self-efficacy, self-esteem, and social support and the positive changes appeared to last for at least four to five months.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2017.05a
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• pp.99-103
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• 2017

As a development test of the 75-tonf LOx/Kerosene liquid rocket engine for KSLV-II first Stage Engine, hot firing test of 75-tonf engine are performed. The current status of development test on first stage 75-tonf engine system including combustion chamber, turbopump, gas generator, propellant supply system are presented. During the 75tonf engine test campaign, the development of startup sequence of LOx-Kerosene engine system, engine startup using pyrostarter, ignition of gas generator, steady operation and engine shutdown is successfully performed. As a passenger test during engine hot firing tests, Thrust Vector Control system (TVC) of the engine are also evaluated during engine hot firing test. The results of hot firing test of 75-tonf thrust engine system will be used for the design confirmation and performance evaluation of 75 tonf engine system for KSLV-II first Stage.

• Journal of Digital Convergence
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• v.13 no.10
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• pp.377-383
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• 2015

This study evaluates the convergence radiation protection performance by measuring the PSNR(peak signal-to-noise ratio) values of the image J in the image evaluation program based on increased relative to this exposure of radiation workers.The aim of this study was to evaluate radiation protection performance of apron for design of it's basic information. Method was used to PSNR of Image J program and good condition apron was more than 27dB, the PSNR value of poor condition apron appeared to be less than 24dB. The result is the normality were satisfied distribution and T-test values were statistically significant with p<0.001. Results of evaluation of the performance protective apron through the more easily accessible experimental conditions and methods in the clinical was confirmed distinctly different. in order to reduce the radiation exposure we need to evaluate convergence protection performance and to be having a good performance apron.

• Journal of the Korean Geosynthetics Society
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• v.19 no.2
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• pp.1-11
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• 2020

The lateral bearing characteristics of large diameter drilled shaft depend greatly on the stiffness of the pile, horizontal subgrade reaction of adjacent ground. In particular, the empirical evaluation results of the horizontal subgrade reaction coefficient which are widely used in pile design are very important factors in evaluating the lateral bearing capacity of drilled shaft because the difference in bearing capacity depends on the estimated result. Nevertheless, the evaluation of the horizontal subgrade reaction coefficient on the large diameter drilled shaft is insufficient. In addition, although the range of influence and the location of the maximum moment which is the weaken zone on the pile may be correlated and relationship of these are major consideration in determining the reinforced zone of drilled shaft, the previous studies have not been evaluated it. In this study, the field test and nonlinear analysis of large diameter drilled shaft were performed to evaluate the horizontal subgrade reaction coefficient and to investigate the relationship between the influence range 1/β of the pile and the location of the maximum moment z_m. In the result, the lateral bearing capacity of drilled shaft showed a difference in results by about 190% according to the empirical equation on the horizontal subgrade reaction coefficient. And the relationship between the influence range of the pile and the location of the maximum moment was evaluated as a linear relationship depending on the soil density.

• Korean Journal of Health Education and Promotion
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• v.26 no.3
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• pp.85-96
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• 2009

Objectives: The purpose of this study was to assess input for health promoting schools (HPS), and to evaluate HPS based on WHO's guidelines through school characteristics, and to identify the schools' need among six areas of HPS. Methods: A stratified and random cluster sampling design was used to obtain a cross-sectional sample. A total of 59 elementary, middle and high schools in Seoul and Gyeonggi areas were included, and 333 teachers (males 40.6%, females 59.4%) participated in this survey. A self-reported questionnaire consisted of ten items for input for HPS, 50 items for the evaluation of HPS and three items for the schools' needs among six areas of HPS. Data was analyzed through a t-test, ANOVA, and a Duncan test. Results: The mean score of input for HPS was 48.5 ($\pm$15.3). Elementary schools had higher mean scores of input than middle schools. The mean score of schools with a management committee was higher than those schools without it. The schools which had meetings on health issues had higher mean scores. The mean score for HPS was 76.8 ($\pm$9.4): the area of "School Physical Environment" had the highest score (80.0$\pm$10.9), and the area of "Community Relationships" had the lowest score (67.1$\pm$13.9). Elementary schools had higher mean scores of HPS than middle and high schools. The schools which had less than nine classes and more than 31 classes had higher mean scores. The mean scores of schools with less than 340 students and more than 1201 students had higher. The schools which had meetings on health issues had higher mean scores. The same results were found on six areas of HPS. The teachers responded that the areas of "School Health Policy", "The School Physical Environment", and "Health Service" should be supported among the six areas of HPS. Conclusion: Based on these results, more concerns and support for school health are necessary. Middle schools should give more regard on the development of HPS. For comprehensive school health promotion, all six areas of HPS should be equally supported.

• Journal of the Korean Institute of Landscape Architecture
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• v.36 no.4
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• pp.74-82
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• 2008

The purpose of this study is to reflect on the results of the assessment and analysis of landscape planning projects according to planning phases in a landscape planning system based on landscape law. An assessment of the importance and performance of landscape planning elements by planning phases was studied by statistically descriptive analysis, variation analysis, statistical t-test and importance-performance analysis. As a result of the evaluation, the performance of existing landscape planning projects is 3.813 and the importance of planning elements is 5.648. This means that in spite of the importance of landscape planning elements, the performance of existing landscape planning projects is not sufficient to cover the importance of landscape planning elements. In addition, 'site landscape survey' and 'landscape design guideline' sections are not sufficient when they are compared to 'landscape concept plan' and 'landscape basic plan' to complete the landscape planning projects required by landscape law. It means also that the landscape survey and landscape design guidelines should be complementarily practiced in order to increase the effectiveness of landscape planning projects. As the research is practiced by survey methods on landscape planning projects which are only new development sites, the results cannot represent all types of landscape planning projects. Nevertheless, the results can be applied to new landscape planning at new development sites or old cities to increase effectiveness.

• Journal of the Korean Wood Science and Technology
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• v.38 no.6
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• pp.470-479
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• 2010

In this study, the visual grading based on the visual characteristics and structural timber bending test were conducted for domestic yellow poplar dimension lumber. Structural performance of domestic yellow poplar dimension lumber was conducted through the evaluation of strength and stiffness. Visual grading rule of yellow poplar dimension lumber did not exist in Korea. Visual grading of yellow poplar dimension lumber was performed according to the NSLB (Northern Softwood Lumber Bureau) standard grading rules including several hardwood dimension lumber. The allowable bending stress was calculated from the results of a visual grading. Compared with NDS (National Design Specification), the yellow poplar dimension lumber showed enough strength for structural uses. In addition, the visual grading was performed according to the KFRI (Korea Forest Research Institute) grading rule to calculated allowable bending stress and to evaluated the feasibility. The yellow poplar was classified into the pine groups by the KFRI criteria regulated by specific gravity. Allowable bending stress based on weibull distribution had became highly than KFRI criteria, as No. 1 (10.0 MPa), No. 2 (7.4 MPa) and No. 3 (4.1 MPa). And the availability of yellow poplar dimension lumber for structural uses had been confirmed. The Modulus of Elasticity (MOE) of domestic yellow poplar dimension lumber had not met the NDS and KFRI criteria. However, for the use of domestic yellow poplar, average values of MOE which obtained through this test were suggested as design value for domestic yellow poplar. Design values were supposed No. 1, 2 (9,000 MPa) and No. 3 (8,000 MPa).

• Applied Chemistry for Engineering
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• v.30 no.1
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• pp.62-67
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• 2019

This study was focused on the design and the performance analysis of integral Hot BoP for recovering waste heat from high-temperature exhaust gas in 2 kW class solid oxide fuel cell (SOFC). The hot BoP system was consisted of a catalytic combustor, air preheater and steam generator for burning the stack exhaust gas and for recovering waste heat. In the design of the system, the maximum possible heat transfer was calculated to analyze the heat distribution processes. The detail design of the air preheater and steam generator was carried out by solving the heat transfer equation. The hot BoP was fabricated as a single unit to reduce the heat loss. The simulated stack exhaust gas which considered SOFC operation was used to the performance test. In the hot BoP performance test, the heat transfer rate and system efficiency were measured under various heat loads. The combustibility with the equivalent ratio was analyzed by measuring CO emission of the exhaust gas. As a result, the thermal efficiency of the hot BoP was about 60% based on the standard heat load of 2 kW SOFC. CO emission of the exhaust gas rapidly decreased at an equivalent ratio of 0.25 or more.