• Journal of The Korean Society of Agricultural Engineers
• /
• v.61 no.1
• /
• pp.85-93
• /
• 2019

The objective of this study is to assess the environmental effect of the reclaimed land drainage method using oyster shell through the Life cycle $CO_2$ assessment, and to evaluate the applicability in South Korea. In this Study, the life cycle $CO_2$ emissions of oyster shell (OS) and crushed stone (CS, as avoided product) were assessed and compared. The Life Cycle Assessment method was used for quantitative evaluation of direct or indirect environmental effects of OS recycling. $CO_2$ was selected as the evaluation target material, and the scope of assessment includes the acquisition of materials, processing, transportation, construction phases. Compared to using CS, 77.0% of $CO_2$ emissions in acquisition and processing, 47.0% in transportation and 6.5% in construction phase were reduced, respectively by using of OS. The maximum transportation distance of OS was estimated according to transportation distance of CS. OS has environmental advantages than CS within about 26 - 101 km from the source. OS was found to be applicable to reclaimed lands up to 810 ha, 3,910 ha from Tongyeong and Yeosu, respectively. In addition, the amount of OS that could be used as drainage material for reclaimed land was much higher than annual OS production of South Korea. Therefore, it is considered that OS is sufficient to be used as drainage material for reclaimed land in South Korea.

• International Journal of Advanced Culture Technology
• /
• v.8 no.4
• /
• pp.89-94
• /
• 2020

This study attempted to investigate cognitive load, vividness, and cybersickness in nursing students, in the last year of nursing college, who used a 360-degree video content for studying intravenous fluid infusion, one of the core fundamental nursing skills. The aim was to determine the correlation between the variables, and to decide whether the 360-degree video content can be used as an effective supplementary educational material in the regular curricula. This study, a descriptive research, was conducted from October 31, 2019 to November 14, 2019. The participants in this study were 64 students in the 4th year of nursing college at a university located in B City, South Korea. They were instructed to watch a 360-degree video content for intravenous infusion using a Samsung Head Mounted Display (HMD) while ensuring the safety of the students. The results showed that the scores, out of 7 points, for material design, self-evaluation, and physical effort for cognitive load in nursing students were 5.93±0.71, 5.92±0.71, and 5.64±0.74 points, respectively. In addition, the scores, out of 7 points, for mental effort and task difficulty were 2.55±1.08 and 1.94±0.75 points, respectively, and the scores for vividness and cybersickness in the participants were 5.82±0.84, and 2.57±0.98 points, respectively. Physical effort, self-evaluation, and material design for cognitive load in the participants were positively correlated with vividness (r=.379, r=.458, r=.507). In addition, mental effort for cognitive load was positively correlated with cybersickness (r=.684), whereas self-evaluation and material design were negatively correlated with cybersickness (r=-.388, r=-.343). Based on the results of this study, we believe that the 360-degree video content for intravenous fluid infusion can be used as an educational medium in regular and non-regular curricula. In addition, future studies are needed to specifically develop and verify teaching and learning methods on how to apply 360-degree video contents..

• Fashion & Textile Research Journal
• /
• v.23 no.6
• /
• pp.781-789
• /
• 2021

To enhance the design and comfort of waist-protection corsets, this study analyzed the product characteristics of five types of posture-correction corsets that are available commercially. Additionally, subjective evaluation of the corsets was conducted on women aged 20 to 60 years, in terms of design, material preference, fit, comfort, degree of correction, freedom of movement, tightness, and convenience of front fastening. Following product analysis, the five corset types were divided into: two soft, one semi-hard, and two hard types in terms of the degree of elongation. As a result of pattern analysis, the soft type was designed to improve fit by reflecting the body curvature, whereas the semi-hard and hard types were relatively flat. Through the wearing sensation assessment, the hard type manufactured by company S was the best in terms of design, material, fit, comfort, correction degree, and freedom of movement. The soft type was average in design, material, and fit while relatively poor in the correction degree and tightness. The results indicated that soft materials, flexible bones with appropriate tension, patterns designed to snugly fit the body with large curvature at the top and bottom for better inflection, and adjustable support belts that can be double-fixed are crucial elements in improving the corset design to boost the comfort of wearing. These study results are helpful in the development of waist-protection corsets with excellent wearing comfort and design appreciated by customers.

• Journal of Aerospace System Engineering
• /
• v.17 no.5
• /
• pp.19-27
• /
• 2023

In this study, we used finite element analysis to conduct a containment capability evaluation of a turbine case. When analyzing the impact behavior of structures subjected to impact loads, it is important to consider the strain rate, as it affects the increase in flow stress. Therefore, we applied three material models (Cowper-Symonds, Johnson-Cook, and Modified Johnson-Cook) for the impact analysis. To validate these material models, we performed an impact test on an aluminum 6061 plate. By comparing and analyzing the experimental and analytical results, we determined that the Modified Johnson-Cook material model exhibited the least error. As a result, we applied this material model to evaluate the containment capability of the turbine case. This evaluation involved determining the occurrence of penetration, as well as the stress and strain induced at the collision area due to the initial velocity of the blade.

• Proceedings of the Materials Research Society of Korea Conference
• /
• 1998.08a
• /
• pp.82.3-82
• /
• 1998

• Journal of the Korea Concrete Institute
• /
• v.19 no.1
• /
• pp.39-46
• /
• 2007

In this study, for the establishment of the performance evaluation methods and the quality control standards of durability recovery method, the quantitative exposure data by long term exposure test under the coast and normal atmosphere is accumulated and analyzed. Investigating and evaluating the result of exposure test during 30 months of exposure age under the coastal and normal atmosphere environment, carbonation depth and chloride-ion penetration depth very little penetrated than cover depth. It seems reasonable to conclude that main cause of Corrosion of reinforcing bar are chloride-ion and macro cell from the result of corrosion area and corrosion velocity. Therefore, it is considered to be applied as the fundamental data on the performance evaluation and quality control standards of repair material and method through continuous exposure test in the future.

• Journal of the Korean Society for Nondestructive Testing
• /
• v.27 no.5
• /
• pp.398-408
• /
• 2007

For better evaluation of material thickness by using the reflection type pulsed eddy current method, various probe models are designed and their response signals, characteristics, and sensitivities to thickness variation are investigated by a numerical analysis method. Since the sensor needs to detect magnetic fields from eddy currents induced in a test material, not from the exciter coil, two types of models that are shielded by the combination of copper and ferrite and only by ferrite are considered. By studying response signals from these shielded probe models, the peak value and the zero crossing time are selected as useful signal features for the evaluation of material thickness. Investigation of sensitivities of these two features shows that the sensitivity of peak value is more useful than that of zero crossing time and that the probe shielded only by ferrite gives much better sensitivity to thickness variation.

• The Journal of Korean Association of Computer Education
• /
• v.11 no.4
• /
• pp.1-12
• /
• 2008

This paper proposes basic algorithmic thinking based problem models applicable immediately without additional learnings and it problems basic problems and evaluation methods using material factors in an elementary course of mathematics For these purposes, an algorithmic thinking based problem model and it's basic problem models are proposed based on flowchart design methods with 5 degrees of difficulties. And algorithmic thinking based basic problems are developed by applying the proposed basic problem models into material domain in an elementary course of mathematics. And this paper proves the validity of developed basic problems in defining then as algorithmic thinking based basic problems through experiments and statistical analyses. The experimental results are analyzed in views of variety and effectiveness evaluation of answer algorithms and suitability of allocating 5 degrees of difficulties to the developed basic problems.

• Transactions of the Korean Society of Pressure Vessels and Piping
• /
• v.13 no.2
• /
• pp.60-66
• /
• 2017

The standard master curve (MC) approach has the major limitation because it is only applicable to homogeneous datasets. In nature, materials are macroscopically inhomogeneous and involve scatter of fracture toughness data due to various deterministic material inhomogeneity and random inhomogeneity. RPV(reactor pressure vessel) steel has different fracture toughness with varying distance from the inner surface of the wall due to cooling rate in manufacturing process; deterministic inhomogeneity. On the other hand, reference temperature, $T_0$, used in the evaluation of fracture toughness is acting as a random parameter in the evaluation of welding region; random inhomogeneity. In the present paper, four regions, the surface, 1/8T, 1/4T and 1/2T, were considered for fracture toughness specimens of KSNP (Korean Standard Nuclear Plant) SA508 Gr. 3 steel to investigate deterministic material inhomogeneity and random inhomogeneity. Fracture toughness tests were carried out for four regions and three test temperatures in the transition region. Fracture toughness evaluation was performed using the bimodal master curve (BMC) approach which is applicable to the inhomogeneous material. The results of the bimodal master curve analyses were compared with that of conventional master curve analyses. As a result, the bimodal master approach considering inhomogeneous materials provides better description of scatter in fracture toughness data than conventional master curve analysis. However, the difference in the $T_0$ determined by two master curve approaches was insignificant.

• Korean Institute of Interior Design Journal
• /
• no.28
• /
• pp.117-123
• /
• 2001

In 1990s, interest on Environment has been increased and Environment-oriented consumer's economic power accelerated the trend of preference for 'Environment-friendly material'. Moreover, the concept of 'Sick Building' Syndrome has been spread to the public and solution for the syndrome is required. 'Environment-friendly material'means that the material used is not harmful for the user's health, and on top of that, causes least harm to the environment during production/scrap process of the material itself. Decision of designers and architectures, as a result, is really crucial tot he environment issues. Above all, selecting the most environment-friendly material and design among possible candidates is natural and cost saving way. In the paper, couple of Evaluation Criterium for Material Selection are analyzed and objective linkage has been identified. With the result of analysis, methodology to minimize damage on environment during whole life cycle of the Interior Design has been sought for.