• Advances in materials Research
• /
• v.13 no.2
• /
• pp.129-140
• /
• 2024

This study evaluates the ratio of Toluene di-isocyanate (TDI) functional group isocyanate (NCO) to the binder functional hydroxyl group (OH) in HTPB/AP/Al-based propellants on their mechanical properties, flow rate, and viscosity to determine the limitations of NCO/OH in the composition of solid propellants. The propellants consisted of hydroxyl-terminated polybutadiene (HTPB) polyurethane (PU), aluminum (Al) and tri-modal ammonium perchlorate (AP). The tri-modal AP consisted of 30% of coarse AP, 30% of medium AP, and 8% of fine AP. The ratio of NCO/OH varies from 0.73 to 0.85, with two binder percentages of 10.5% and 12%. An increase in NCO/OH ratio with 10.5% binder provided 20%, 95%, and 8 to 9% increments in UTS, modulus, and hardness, respectively. However, the propellant elongation, density, and flow rate decreased by 170%, 0.2%, and 11-12%, respectively. Viscosity increased 20% based on initial hour reading. The 12% binder provides 27%, 47%, and 5~6% an increment of UTS, modulus and hardness respectively. However, the propellant elongation, density, and flow rate decreased by 47%, 0.17% and 27%, respectively. The viscosity increased 30% based on initial hour reading. This study suggests the NCO/OH value of 0.77 and 10.5~11% binder content in propellant based on the mechanical properties, flow rate, and viscosity for better processing and pot life.

• IMMUNE NETWORK
• /
• v.13 no.2
• /
• pp.43-54
• /
• 2013

Over the past 40 years, flow cytometry has emerged as a leading, application-rich technology that supports high-resolution characterization of individual cells which function in complex cellular networks such as the immune system. This brief overview highlights advances in multiparameter flow cytometric technologies and reagent applications for characterization and functional analysis of cells modulating the immune network. These advances significantly support highthroughput and high-content analyses and enable an integrated understanding of the cellular and molecular interactions that underlie complex biological systems.

• Journal of the Korean Ceramic Society
• /
• v.49 no.3
• /
• pp.231-235
• /
• 2012

Plasticity is the ability of clay to respond to pressure with a continuous and permanent change of shape in any direction without breaking apart, and hold that shape when released. In this work, the effect of water content and aging period on the plasticity of porcelain clay was evaluated using the capillary rheometer to measure the flow rate and the shear stress. The shear stress of porcelain clay was slightly increased with increasing the aging period, indicating that the plasticity of porcelain clay was influenced by an organic content. It was also observed that the water content in the porcelain clay had a great influence on the plasticity of porcelain clay. The shear stress with water content of 21 wt% was sharply increased with increasing shear rate, but the shear stresses with water contents of 24 and 27 wt% is gently incremented.

• International Journal of Concrete Structures and Materials
• /
• v.9 no.2
• /
• pp.185-206
• /
• 2015

This paper presents statistical models developed to study the influence of key mix design parameters on the properties of lightweight self-consolidating concrete (LWSCC) with expanded shale (ESH) aggregates. Twenty LWSCC mixtures are designed and tested, where responses (properties) are evaluated to analyze influence of mix design parameters and develop the models. Such responses included slump flow diameter, V-funnel flow time, J-ring flow diameter, J-ring height difference, L-box ratio, filling capacity, sieve segregation, unit weight and compressive strength. The developed models are valid for mixes with 0.30-0.40 water-to-binder ratio, high range water reducing admixture of 0.3-1.2 % (by total content of binder) and total binder content of $410-550kg/m^3$. The models are able to identify the influential mix design parameters and their interactions which can be useful to reduce the test protocol needed for proportioning of LWSCCs. Three industrial class ESH-LWSCC mixtures are developed using statistical models and their performance is validated through test results with good agreement. The developed ESH-LWSCC mixtures are able to satisfy the European EFNARC criteria for self-consolidating concrete.

• Journal of Biosystems Engineering
• /
• v.22 no.3
• /
• pp.279-288
• /
• 1997

This study was worked out to obtain fundamental data needed for developing a continuous type dryer. The drying process in a cross-flow type continuous dryer was expressed as partial differential equations, and a drying simulation model for predicting rice moisture content, rice temperature, drying air absolute humidity, drying air temperature was developed by using the finite difference method. To validate the performance of the drying simulation model, a prototype continuous dryer was constructed in this study. The size of the test dryer was one-tenth to that of a commercial continuous dryer. The difference in the outlet rice moisture content between the predicted values and the measured values was within 0.5%, that of outlet rice temperature was below $3^{\circ}C$, that of drying air temperature in drying bed was within $8^{\circ}C$ and that of relative humidity of outlet drying air was big because of the different measuring point. In addition, a drying simulation model for a actual size continuous dryer with double flow was developed in this study. This drying simulation model included the rice mixing effect in the middle of drying length. The difference of outlet moisture content between the predicted and the measured values showed below 0.5% in this study.

• Transactions of the Korean hydrogen and new energy society
• /
• v.31 no.5
• /
• pp.467-479
• /
• 2020

Various researches are being conducted to reduce greenhouse gases generated by the consumption of traditional energy resources. This study was conducted to numerically analyze the combustion characteristics and N-S reaction behavior with respect to the H₂ content of syngas composed of CO and H₂ in pressurized air combustion. A non-premixed opposed flow flame model was applied a modified detailed mechanism with S-chemistry was developed based on GRI 3.0 to simulate the syngas reaction. As the hydrogen content increased, the flame thickness increased due to the fast reactivity of hydrogen. In the rich region, NO and SO₂ were reduced by reaction with H radical and H bonding of NO was suppressed by the formation of HOSO.

• Journal of the Korean Ceramic Society
• /
• v.20 no.2
• /
• pp.166-172
• /
• 1983

In this study the sillicon-alloyed isotropic pyrolytic carbon was deposited in the tumbling bed from the pyrolysis of propane and silicon tetrachloride and investigated whether the silicon-alloyed isotropic pyrolytic carbon deposited in this study was usable as bionaterial or not. The silicon-allyed isotropic pyrolytic carbon was varied by controlling the process variables such as propane con-concentration and the argon flow rate flowing in to the silicon tetrachloride bubbler at a fixed reaction bed tempera-ture of 120$0^{\circ}C$ a rotation of reaction tube of 40 rpm a bed particle weight of 7.5 g and a total flow rate of 21/min; the propane concentration was varied from 10 to 70 and the argon flow rate flowing into the silicon tetrachloride bubble from 0 to 1000 cc/min. The results show that the silicon-alloyed isotropic pyrolytic carbon was obtained at all conditions investigated, . And then the alloyed silicon content is rangion from 7 to 14.5 wt%. The density and deposition rate of deposited silicon-alloyed isotropic carbon increased axxording to silicon content and propane concentration. And the apparent crystal-size(Lc) of pyrolytic carbon is not changed with silicon content. The density and apparant crystallite size are respec-tively in the range of 1.94 to 2.06 and 20 to 25$\AA$ It is shown that the silicon-alloyed isotropic pyrolytic carbon ob-tained in this experiment is usable as biomaterial.

• Korea Science and Art Forum
• /
• v.37 no.3
• /
• pp.125-134
• /
• 2019

This study was conducted to organize a program to classify and analyze the characteristics of images for the automation of background music selection in the video content production process. The results and contents of the study are as follows: video characteristics are selected as subject category, emotion, pixel motion speed, color, and character material. Subject categories and feelings were extracted using Microsoft's Azure Video Indexer, Pixel Movement Speed was an Optional flow, Color was an Image Histogram for Image, and character materials was CNN(Convolutional Neural Network). The results of this study are significant in that video analysis was conducted to match background music in the recent content production process of 'Internet One-person Broadcasting Creators'.

• Journal of Digital Convergence
• /
• v.20 no.2
• /
• pp.389-398
• /
• 2022

Recently, tourism and leisure related VR contents have gained attention of potential tourists. Therefore, this study aimed to analyze investigate the effects of 360-degree VR tourism contents motivations, flow, continuance usage intention on visit intention for Chinese student in Korea. This study found that hedonic benefit and personal benefit exerted a positive influence on visit intention of contents users. However, vividness and usability did not influence on visit intention. Moreover, flow exerted a significant influence on visit intention but continuance usage intention did not influence on visit intention. The study is significant in shedding light on whether the motivations, flow, continuance usage intention of 360-degree VR tourism contents influences visit intention. It is suggested that the consumption of 360-degree VR tourism contents can be a useful marketing tool for strength of intention to visit.

• Journal of Korea Game Society
• /
• v.13 no.3
• /
• pp.55-68
• /
• 2013

This study examined the factors determining experience of flow in mobile social network games. Built upon the literature on flow experience in the Internet and online games, this study classified the determining factors into three categories. The first category is the content factor which includes graphic design, challenge, and incentive; the second is the device factor including ease of access and ease of control; the third is the social factor including social interaction and community activities. A correlation analysis was conducted to examine the association between each of the seven determining factors and flow experience. Additionally, a hierarchical regression analysis was performed to evaluate which of the selected factors would exert a relatively strong influence on experience of flow. Both analyses reached the same conclusions as follows: Graphic design, incentive, and community activities increase flow experience while challenge and ease of control exert little influence on flow experience. In addition, graphic design was the most influential element in determining flow experience, followed by community activities and incentive, respectively.