• Nuclear Engineering and Technology
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• v.35 no.4
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• pp.274-285
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• 2003

Film boiling heat transfer coefficients for a downward-facing hemispherical surface are measured from the quenching tests in DELTA (Downward-boiling Experimental Loop for Transient Analysis). Two test sections are made of copper to maintain Bi below 0.1. The outer diameters of the hemispheres are 120 mm and 294 mm, respectively. The thickness of both the test sections is 30 mm. The effect of diameter on film boiling heat transfer is quantified utilizing results obtained from the two test sections. The measured heat transfer coefficients for the test section with diameter 120 mm lie within the bounding values from the laminar film boiling analysis, while those for diameter 294 mm are found to be greater than the numerical results on account of the Helmholtz instability. There is little difference observed between the film boiling heat transfer coefficients measured from the two test sections. In addition, the higher thermal conductivity of copper results in the higher minimum heat flux in the tests. For the test section of diameter 120 mm, the Leidenfrost point is lower than that for the test section of diameter 294 mm. Destabilization of film boiling propagates radially inward for the 294 mm test section versus radially outward for the 120 mm Test Section.

• Steel and Composite Structures
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• v.19 no.2
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• pp.441-465
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• 2015

This paper presents the experimental results of flexural and compression steel members strengthened with carbon fiber reinforced polymers (CFRP) sheets. In the flexural test, the five specimens were fabricated and the test parameters were the number of CFRP ply and the ratio of partial-length bonded CFRP sheets of specimen. The CFRP sheet strengthened steel beam had failure mode: CFRP sheet rupture at the mid span of steel beams. A maximum increase of 11.3% was achieved depending on the number of CFRP sheet ply and the length of CFRP sheet. In the compression test, the nine specimens were fabricated and the main parameters were: width-thickness ratio (b/t), the number of CFRP ply, and the length of the specimen. From the tests, for short columns it was observed that two sides would typically buckle outward and the other two sides would buckle inward. Also, for long columns, overall buckling was observed. A maximum increase of 57% was achieved in axial-load capacity when 3 layers of CFRP were used to wrap HSS columns of b/t = 60 transversely.

• Corrosion Science and Technology
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• v.21 no.1
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• pp.53-61
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• 2022

Alloys of Fe-(5.3-29.8)%Mn-(1.1-1.9)%Al-(0.4-0.5)%C were oxidized at 550 ℃ to 650 ℃ for 20 h to understand effects of alloying elements on oxidation. Their oxidation resistance increased with increasing Mn level to a small extent. Their oxidation kinetics changed from parabolic to linear when Mn content was decreased and temperature was increasing. Oxide scales primarily consisted of Fe₂O₃, Mn₂O₃, and MnFe₂O₄ without any protective Al-bearing oxides. During oxidation, Fe, Mn, and a lesser amount of Al diffused outward, while oxygen diffused inward to form internal oxides. Both oxide scales and internal oxides consisted of Fe, Mn, and a small amount of Al. The oxidation of Mn and carbon transformed γ-matrix to α-matrix in the subscale. The oxidation led to the formation of relatively thick oxide scales due to inherently inferior oxidation resistance of alloys and the formation of voids and cracks due to evaporation of manganese, decarburization, and outward diffusion of cations across oxides.

• Tribology and Lubricants
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• v.38 no.6
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• pp.281-286
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• 2022

In this study, the effects of Elasto-hydrodynamic lubrication pressure on the critical shoulder height of raceway in an angular contact ball bearing were investigated. Both 3D contact analyses using an influence function and the EHL analysis were conducted for the contact geometry between the ball and raceways. The pressure distributions by 3D contact analysis and EHL analysis for an example bearing were compared. The effect of ellipse truncation on the minimum film thickness also investigated from EHL analysis. The critical shoulder height in the dry contact and the EHL state were compared for various applied loads. It is shown that when the ellipse truncation occurs, the pressure spike for the EHL conjunction is higher than that for the dry contact, and its location moves more inward of the contact center. The steep pressure gradients would increase the flow rate, so in order to maintain flow continuity a significant reduction in film thickness and an abrupt rise in pressure occurs in the edge of shoulder. Significant reduction of the minimum film thickness occurs near the edge of shoulder. The critical shoulder heights in the EHL state are calculated as higher values compared with in the dry contact. This results shows that the determination of critical shoulder height by the EHL analysis is more proper.

• Journal of Distribution Science
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• v.17 no.6
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• pp.5-13
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• 2019

Purpose - The potential for small businesses in the distribution sector to contribute to socio-economic development remains largely inert due to a litany of challenges that they face. Incubators have emerged as the 'silver bullet' for most of the problems but the extent to which they are effectively helping small business overcome their challenges remains debatable. This study seeks to determine the core reasons why respondents enrolled in an incubator, the essence of the incubator and the extent to which the incubator performance is satisfactory. Research design, data, and methodology - A positivist philosophical approach was adopted for the study. This quantitative study used a survey method to collect data from incubatees in a cross-sectional manner. The data were subsequently analysed to generate necessary insights. Results - Results reveal that the gender composition of incubatees is severely skewed in favour of males. Also, most incubatees enrolled in the incubators with a hope that it would ease their pathway to big businesses, financiers and business registration institutions, and it is not. Conclusion - Incubators are mostly inward-looking and are adept at offering training interventions. To improve the effectiveness of incubators, it is necessary to invest efforts in attracting more females and building networks with key external stakeholders that could possibly assist the incubatees establish and grow their businesses.

• Korean Journal of Materials Research
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• v.31 no.8
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• pp.439-444
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• 2021

The oxidation resistance of the diffusion aluminide bond coat (BC) is compromised largely by interdiffusion (ID) effects on coated turbine blades of aeroengines. The present study is designed to understand the influence of ID on βNiAl coatings or BC. In this regard, nickel substrate and CMSX-4 superalloy are deposited. In total, four sets of BCs are developed, i.e. pure βNiAl (on Ni substrate), simple βNiAl (on CMSX-4 substrate), Zr-βNiAl (on CMSX-4 substrate) and Pt-βNiAl (on CMSX-4 substrate). The main aim of this study is to understand the interdiffusion of Al, Zr and Pt during preparation and oxidation. In addition, the beneficial effects of both Zr and platinum are assessed. Pure βNiAl and simple βNiAl show Ni-out-diffusion, whereas for platinum inward diffusion to the substrate is noticed under vacuum treatment. Interestingly, Zr-βNiAl shows the least ID in all BCs and exhibit stability under both vacuum and oxidation treatments. However, its spallation resistance is slightly lower than that of Pt-βNiAl BC. All BCs show similar oxide growth trends, except for Zr-βNiAl, which exhibits two-stage oxidations, i.e. transient and steady-state. Moreover, it is suggested that the localized spallation in all BCs is caused by βNiAl - γ'-Ni₃Al transformation.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.47 no.1
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• pp.37-45
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• 2011

Reduction of ship's rolling is the most important performance requirement for improving the safety of the crew on board and preventing damage to cargo as well as improving the comfort of the ride. It is a common experience for mariners, to see that steering with a rudder generally induces rolling of the ship, though the original aim of the rudder is to keep the ship's heading to the required course. At the first stage, when a rudder is steered, usually a ship heels in an inward direction, due to the roll moment acting on the rudder. At the next stage in steering, the main heel may change to an outward. This coupling between rudder and roll motion has become an attractive problem from the point of view of roll stabilization using the rudder, because it is a natural in sight that if the rudder action is skillfully related to the change of roll as well as to the course deviation, the roll can be reduced to a certain degree. The main aim of this paper is to discuss the results of the actual full-scale sea trials carried out on steer gear No.1 and No.1 2, the individual quartermaster and to make clear their statistical properties, using the actual data which included measurement of roll angle, roll rate and the comparative tests were carried out immediately after each other, in order to minimize any statistical variation in sea conditions. It can be concluded that the steer gear No. 1 2 reduced the roll motion on average by about 21% in comparison with the No.1 and confirmed the some difference as per a ability of quarter-master's maneuver.

• Journal of the Korean Wood Science and Technology
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• v.44 no.4
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• pp.607-615
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• 2016

The delamination along the annual ring on the cross-section of laminae and the bonding strength according to the tangential angle between laminae were evaluated for the production of 3-ply cross-laminated timber (CLT) using domestic larch. Since there is no standard for CLT in Korea, the production and test of specimens for bonding strength followed the standard procedure of "Structural glued laminated timber" (KS F 3021). The standard specifies to exclude any measurement from the cracks of timbers resulted from drying or knots during delamination test of the glued laminated timbers. However, the failure of cross-sectional tissues along the annual rings was observed near the glue-line of all specimens during the delamination test. Because this phenomenon can generate defects in the CLT that may be exposed to various temperatures and relative humidities after the actual construction, the delamination percentage was measured by including this wood failure. As a result, the delamination percentage of the CLT which had been combined in such a way that the annual rings of outer lamina were directed inward was the lowest, which was around 13%, regardless of the annual ring direction of the middle lamina. On the other hand, the delamination percentage of the CLT which had been combined in such a way that the annual rings of outer lamina were directed outward was the highest, which was around 26%. Furthermore, end-split occurred in the outer lamina during the drying process of the boiling delamination test, which affected the delamination percentage. Therefore, the soaking delamination test was found to be more appropriate for evaluating the delamination strength of CLT. The block shear strength of larch CLT was $3.9{\pm}0.9$ MPa on average, which was 46% lower than the block shear strength requirement (7.1 MPa) of the standard, but satisfied the criteria of the block shear strength (3.5 MPa) of the European Standard (prEN 16351: 2013).

• Journal of Animal Science and Technology
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• v.60 no.10
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• pp.24.1-24.8
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• 2018

Background: Following the ban on the importation of import-dependent fed ingredients in most developing countries, the need to look inward for local content is now compelling. Thus, leaf meals that have phytogenic additive potentials are envisaged will be a viable feed ingredient in rabbit diets. Methods: The effect of dietary inclusion of gliricidia leaf meal (GLM) with or without multi-enzyme (E) supplementation in rabbits was investigated using ninety-six 35-day old rabbits of crossbreed (Newzealand and Chinchilla). One basal diet that met the requirements of growing rabbit was formulated (Diet 1). Thereafter, another two diets were formulated to contain 15% GLM and 15% GLM plus multi-enzyme at 1 g/kg and designated as diets 2 and 3 respectively. The rabbits were randomly distributed into the 3 diets (32 rabbits/treatment; 4 rabbits/replicate) and fed their respective experimental diets for 8 weeks. Results: The body weight and daily weight gain of the rabbits fed on GLM free diet and those on GLM-based diets (diets 1 and 2) were similar at finishing period of 63-91 day but have lower (P < 0.01) values than those rabbits fed GLM + E based diet (diet 3) at finishing period (63-91 days) and whole fattening period (35-91 days). The apparent dry matter and crude protein digestibility of rabbits fed control diet and those fed 15% GLM based diet were lower (P < 0.05) than those fed 15% GLM + E-based diet. Triglycerides concentration of rabbits fed 15% GLM-based diet without enzyme addition were lower (P < 0.05) than those observed for rabbits on the rest test diets. Cholesterol and Low-Density Lipoprotein levels of rabbits fed 15% GLM and 15% GLM + E-based diets were lower (P < 0.05) than those fed the GLM free diet. The superoxide dismutase and glutathione peroxidase of rabbits fed the GLM free diet (diet 1) were significantly (P < 0.05) lower than those fed the 15%GLM and 15% GLM + E-based diets. Conclusion: Dietary inclusion of GLM at 15% of the diet did not have a negative effect on the rabbits postweaning period (35-63 days) but will require multi-enzyme supplementation to enhance growth indices at finishing period (63-91 day) without precipitating negative effect on the rabbits' health status.

• Journal of Korea Technology Innovation Society
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• v.16 no.3
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• pp.809-838
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• 2013

Innovation is the development of new customers value through solutions that meet new needs, inarticulate needs, or old customer and market needs in value adding new ways. This is accomplished through more effective products, processes, services, technologies, or ideas that are readily available to markets, governments, and society. Innovation differs from invention in that innovation refers to the use of a better and, as a result, novel idea or method, whereas invention refers more directly to the creation of the idea or method itself. Therefore, the utilization of patents is the most important of the three aspects (creation, protection and utilization) in the patent system for getting to actual innovation. In order to increase the patent use, the rates of the applied patents to a real industrial process and the bargain and license of patent rights should be promoted. For promoting technological innovation substantially, there is necessary to escape from dichotomy of weakening or enhancing patent protection in the discussion on the changes of patent system for "Adequate patent guarantees". Furthermore, the legal and institutional improvements to enable the use of patent should be discussed together. Recently, open innovation is a new paradigm that assumes that firms can and should use external ideas as well as internal ideas, and internal and external paths to market, as the firms look to advance their technology" or "Innovating with partners by sharing risk and sharing reward." The boundaries between a firm and its environment have become more permeable; innovations can easily transfer inward and outward. The central idea behind open innovation is that in a world of widely distributed knowledge, companies cannot afford to rely entirely on their own research, but should instead buy or license processes or inventions (i.e. patents) from other companies. In addition, internal inventions not being used in a firm's business should be taken outside the company. In the era of open innovation, more flexible patent use strategy is essential. It is important that improvements for the legal system in order that patented technology can be applied for products and processes in a real industrial between outside and inside of the firms.