• Journal of Ocean Engineering and Technology
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• v.14 no.2
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• pp.99-105
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• 2000

This paper describes the effect of specimen size on fatigue crack growth rate for the offshore structural high-tensile-strength steel BS4360 and machine structural steel SM45C. The purpose of the present study is to investigate the effect of stress ratio aspect ratio specimen width and specimen thickness of the fatigue crack growth behavior. Compact tension specimens with a LT orientation for BS4360 and SM45C steels were used, All testing was done at constant stress intensity factor range controlled fatigue crack growth condition. The investigation demonstrates that the fatigue crack growth rate is increased with increasing stress ratio and specimen thickness and is decreased with increasing specimen width. The fatigue crack growth rate is unaffected by aspect ratio until a/W=0.50 but is increased by increasing spect ratio from a/W=0.55.

• Korean Institute of Interior Design Journal
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• v.27 no.3
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• pp.136-144
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• 2018

The purpose of this study is to examined the unconscious response of the pupil in the observation toward the image in the eye-tracking experiments that target on a large complex cultural space. Twenty-five men participated in this experiment and the observation data were analyzed in seconds per minute on watching time. It could examine the unconscious response of information searching in the change of pupil size in the process of observing the space. The results could be defined as following several points. First, it was possible to outline the unconscious response characteristics of pupil by analyzing sudden changes in pupil size as total, cumulative, and individual. The response characteristics using frequency and time can be utilized as the analytical method to examine the degree of interest of spatial components according to the purpose of analysis in the future. Second, according to the over ${\pm}5%$ of cumulative variation rate on the pupil size change, during in the 60 seconds, the continuous pupil dilation was used 25.2 seconds in 8.8 rounds and the pupil reduction was used 18.0 seconds in 7.0 rounds. Third, when the variation rate of ${\pm}5%$ or more was regarded as the sudden changes on pupil size by individual variation, the pupil dilation was 7.2 rounds of 8.6 seconds and pupil reduction was 6.0 seconds in 5.0 rounds. This means that the pupil increases 9.3% in one expansion and decreases -8.5% in the reduction process. As regarding pupil changes as cumulative rate, it appeared high change rate on pupil reduction but it became higher on pupil dilation in individual.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.53 no.1
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• pp.132-138
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• 2020

Marphysa sanguinea is the most well-known polychaete species with a high economic value. However, this species has a high mortality in the early rearing stage of aquaculture. This study was conducted to find out the optimal substrate size and organic contents for the growth and survival rate of M. sanguinea larvae and juveniles. It was observed that the smaller grain size (<Ø 0.063 mm) and high organic contents (5-10%) induced settlement and reduced settlement time of larvae. Moreover, the growth and survival rate of larvae reached high levels at Ø 0.004-0.016 mm of grain sizes and 5-7.5% of organic contents as advantageous substrates for settlement. The survival rate of juveniles reached over 90% in less than Ø 0.016 mm substrate on 15-day experiment for different grain sizes of substrates. These results indicated that substrate compositions of less than Ø 0.016 mm of sand size and 5-7.5% of organic contents in mud will enhance the productivity of M. sanguinea at the early stage.

• Geomechanics and Engineering
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• v.35 no.5
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• pp.475-486
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• 2023

Ballast particles have an irregular shape and are discrete in nature. Due to the discrete nature of ballast, it exhibits complex mechanical behaviour under loading conditions. The discrete element method (DEM) can model the behaviour of discrete particles under a multitude of loading conditions. DEM is used in this paper to simulate a series of three-dimensional direct shear tests in order to investigate the shear behaviour of railway ballast and its interaction at the microscopic level. Particle flow code in three dimension (PFC3D) models the irregular shape of ballast particles as clump particles. To investigate the influence of particle size distribution (PSD), real PSD of Indian railway ballast specification IRS:GE:1:2004, China high-speed rail (HSR) and French rail specifications are generated. PFC3D built-in linear contact model is used to simulate the interaction of ballast particles under various normal stresses, shearing rate and shear box sizes. The results indicate how shear resistance and volumetric changes in ballast assembly are affected by normal stress, shearing rate, PSD and shear box size. In addition to macroscopic behaviour, DEM represents the microscopic behaviour of ballast particles in the form of particle displacement at different stages of the shearing process.

• Reproductive and Developmental Biology
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• v.35 no.2
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• pp.131-136
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• 2011

The in vitro maturation rate of vitrified-thawed canine oocytes was $30.8{\pm}3.4%$. The in vitro maturation rate of vitrified oocytes was lower than that of the control ($52.0{\pm}2.5%$, p<0.05). The in vitro maturation rate of vitrified-thawed oocytes were significantly (p<0.05) lower than those of fresh oocytes. The in vitro maturation and developmental rates of the vitrified-thawed oocytes were $17.5{\pm}2.5%$ and $8.8{\pm}3.4%$, respectively. This results were lower than the control group ($43.6{\pm}3.2%$ vs $20.0{\pm}3.0%$). SOD1 gene expression of 1~2 mm of follicle size were higher than those of above 6 mm follicle size. SOD2 gene expression of 1~2 mm of follicle size were significantly higher than those of above 6 mm follicle size (p<0.01). The expression pattern of SOD1, 2 was constantly expressed in both groups but strongly expressed in follicles (1~2 mm) group when compared to the above 6 mm follicles. SOD gene expression between groups the fresh and vitrified oocytes groups were significant differences in rates. However, RGS gene expression between groups the fresh and vitrified oocytes groups were no significant differences in rates.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.11a
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• pp.227-230
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• 2003

Silicone rubber has very excellent chemical stability and hydrophobicity. A hydrophobic surface can prevent the formation of continuous water films on the surface in wet and heavily contaminated conditions. This phenomenon contributes to the suppression of leakage current and partial discharges on insulator surfaces. Silicone rubber has been used much for housing materials of polymer insulators. ATH is added to the silicone rubber for improvement of its resistance against surface discharge. In this paper, ATH with different particle size and content was added to the silicone rubber during compounding. Silicone rubber was deteriorated by a corona treatment. Hydrophobicity recovery rate after corona treatment and arc resistance of silicone rubber were investigated. Hydrophobicity recovery rate of silicone rubber was evaluated by the measurement of contact angle. Arc resistance was evaluated by measuring weight loss of silicone rubber after arc resistance test. It was observed that the hydrophobicity recovery rate and arc resistance of silicone rubber were different when different particle size and content of ATH were added.

• Journal of Bio-Environment Control
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• v.8 no.4
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• pp.265-274
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• 1999

This experiment was carried out to investigate the effect of container size and substrate volume on the growth and fruit yield of hydroponically grown cucumber(Cucumis sativus L.) plants. Seeds were sown in plug tray filled with coir dust on Feb. 13, 1998. Seedlings with 5 to 6 true leaves were transplanted in $2{\ell},\;4{\ell},\;6{\ell},\;8{\ell}\;and\;10{\ell}$ plastic pots filled with perlite. Cucumber fruits were harvested with 1 to 2 days interval, and fresh weight, number of normal and malformed fruit were recorded. Plant height, stem diameter, number of leaves and leaf area were highly depended on the container size. Total fresh weight and the number of fruit were increased with increasing container size. NAR(net assimilation rate) and CGR(crop growth rate) increased also with increasing the container size. Optimum container size for hydroponically grown cucumber plant using perlite was recommended as $8{\ell}$ per plant.

• Journal of the Korean Society for Heat Treatment
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• v.4 no.3
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• pp.39-46
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• 1991

The effects of austenitizing temperatures and times and cooling rate on the characteristics of continuous air cooling have been investigated for 0.3%C-Mn steels microalloyed with vanadium. Transformation start temperatures have been found to be measured from temperature-time curve directly obtained with continuous air cooling and to decrease with increasing austenitizing temperature, cooling rate and Mn contents. The coarsening behavior of austenite grain size has been measured to abnormally grow at $1050^{\circ}C$ and rapidly grow at $1200^{\circ}C$. It has been found that the volume fraction of pearlite was linealy proportional to the reciprocal square root of austenite grain size. The hardness has been measured to increase with increasing cooling rate up to $250^{\circ}C/min.$ and to remain relatively unchanged in the range of $250{\sim}400^{\circ}C/min.$ showing that hardness valves for steel with a higher Mn content increase more than those for steel with a lower Mn content. The impact property has been found to decrease with increasing of austenite grain size but does not linealy change with the reciprocal square root of austenite grain size.

• Journal of the Korean Society of Industry Convergence
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• v.26 no.1
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• pp.105-112
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• 2023

We analyze the global market for flexible electronic circuits, technical considerations, and analyze the market for application areas and regions. In the market analysis of the application field, the display field has the greatest influence in terms of market size and annual growth rate, and the OLE D lighting market size is expected to grow by nearly 50% in 2026. The multilayer flexible electronics, which dependently requires the semiconductor technology, has a larger market size than other structures and its growth rate is relatively large, leading the market and will be further analyzed in depth. The market size of multilayer flexible electronics applied to display field is expected to show an annual growth rate of 21.1% from $2.7 billion in 2017 to $9.8 billion in 2026, and the OLED market is expected to grow by 75.2% during the same periods. Recently, as electronic products have been miniaturized and advanced, and robust installation in a small space is required, companies that preoccupy multilayer structure or rigid flexible electronic circuit technology have an advantage in competitiveness, so many companies are trying to obtain this technology. These efforts are systematically supported by many countries because they can achieve mutual growth by strengthening the competitiveness of the application field and the same industry. In the case of Korea, a support system is established, but it is required to expand and activate it, and to localize manufacturing equipment and materials.

• Proceedings of the KSME Conference
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• 2007.05b
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• pp.2524-2527
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• 2007

Solid propellant gas generators (SPGG) play a role as a turbopump starter in liquid propellant propulsion systems by supplying pressurized gas to power turbines for engine start. For such a purpose, the propellants should burn with a relative low flame temperature and the combustion gas should not contain corrosive constituents such as chlorine compounds. In accordance with these requirements, stabilized AN-based propellants have been usually used as the most appropriate oxidizer for propellant compositions. However, the burning area of the propellant intends to increase to satisfy the required mass flux because of its low burning rate. Consequently the burning area incensement brings on the SPGG size augmentation. A flow restriction such as filters is applied to decrease the SPGG size by rising up the combustion pressure resulting in increasing the burning rate. The feasibility of the size reduction of SPGG by the employment of filters have been studied. The preliminary results of this study show that the considerable reduction of SPGG size would be achievable just by installing a filter with relatively high pressure loss coefficient.