• Korean Journal of Food Science and Technology
• /
• v.22 no.6
• /
• pp.646-650
• /
• 1990

To develop a new form of spice material by concentration of garlic juice, its rheological properties were investigated. In the temperature range of $15\;to\;65^{\circ}C$, the garlic juice with the solid content of $32\;to\;60^{\circ}Brix$ was considered as a pseudoplastic fluid. Flow and consistency indices of the juice interpreted by power-law equation varied from $0.9937\;to\;0.6130\;and\;0.0041\;to\;3.1886Pa{\;s^n$, respectively. Apparent viscosity was lineally decreased as shear rate was increased. Activation energy for the flow of the garlic juice changed in the range of 11,216 to 23,195 kJ/kg mol.

• Journal of Ocean Engineering and Technology
• /
• v.29 no.3
• /
• pp.241-248
• /
• 2015

A subsea pipeline for oil/gas transportation or gas injection is subjected to extreme variations in internal pressure and temperature, which can involve a strain rate effect on the pipeline material. This paper describes the flow stress characteristics of a pipeline material called API 5L X52N PSL2, using and experimental approach. High-speed tensile tests were carried out for two metal samples taken from the base and weld parts. The target temperature was 100℃, but two other temperature levels of –20℃and 0℃ were taken into account. Three strain rates were also considered for each temperature level: quasi static, 1/s, and 10/s. Flow stress data were proposed for each temperature level according to these strain rates. The dynamic hardening behaviors of the base and weld metals appeared to be nonlinear on the log-scale strain rate axis. A very high material constant value was required for the Cowper-Symonds constitutive equation to support the experimental results.

• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.35 no.10
• /
• pp.1097-1103
• /
• 2011

Liquid droplet impingement erosion (LDIE) is caused by the impact of high-velocity droplets entrained in steam or air on metal. The degradation caused by the LDIE has been experienced in steam turbine internals and high-velocity airplane components (particularly canopies). Recently, LDIE has also been observed in the pipelines of nuclear plants. LDIE among the pipelines occurs when two-phase steam experiences a high pressure drop (e.g., across an orifice in a line to the condenser). In 2011, a nuclear power plant in Korea experienced a steam leak caused by LDIE in a pipe through which a two-phase fluid was flowing. This paper describes a study on the design change of a pipe affected by LDIE in order to mitigate the damage. The design change has been reviewed in terms of fluid dynamics by using the FLUENT code.

• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.38 no.8
• /
• pp.701-707
• /
• 2014

The ecofriendly yellow ocher is used in the manufacturing of cosmetics, construction, and food packaging. The polyethylene terephthalate (PET) used for manufacturing food containers has a microporous structure that causes aeration. Hydrophilic yellow ocher may be applied to hydrophobic PET by surface modification to overcome this issue. The aim of this study is to fabricate a yellow ocher polystyrene hybrid structure in the form of nanoparticles using an optimizing molar ratio of styrene, divinylbenzene, and potassium peroxodisulfate for use in emulsion polymerization. The polymerization was conducted in a yellow ocher suspension that was prepared by dispersing mechanically ground yellow ocher in DI water. The prepared hybrid structure was measured using scanning electron microscopy, energy dispersive X-ray spectroscopy, and X-ray diffraction. The measurement revealed the spherical morphology and Si component that resulted from the yellow ocher in the polystyrene particles. We expect that this hybrid structure would be used as platform material to minimize aeration in PET.

• Composites Research
• /
• v.34 no.6
• /
• pp.350-356
• /
• 2021

When a ship with a planing line operates or turns in a straight line, the floating position and trim change according to the speed, and a large resistance is generated on the hull. In this paper, the resistance to a planing line was estimated through the computational fluid dynamics of a leisure boat with improved hull weight and durability by applying a carbon composite material to the hull. The resistance performance of the bow and stern of the 18ft class leisure boat was checked and the flow field of the entire vessel was estimated, and the stability of the planing line was confirmed by comparing the resistance of each trim through numerical analysis. In addition, it was confirmed that the designed planing line could withstand it sufficiently because the force applied to the hull was not large, and The stability of the boat was analyzed by calculating the wavelength of the wave and the length of the ship as the ratio of gravity to the inertial force and checking how much force the rolling occurred.

• Journal of Korean Tunnelling and Underground Space Association
• /
• v.26 no.3
• /
• pp.209-222
• /
• 2024

The Earth Pressure Balance (EPB) shield Tunnel Boring Machine (TBM) is widely used for underground tunnel construction for its advantages, such as eliminating the need for additional facilities compared to the slurry shield TBM, which requires Slurry Treatment Plant (STP). During EPB shield TBM excavation, a soil conditioning technique is employed to enhance the physical properties of the excavated soil by injecting additives, thus broadening the range of applicable ground conditions to EPB shield TBMs. This study explored the use of xanthan gum, a type of biopolymer, as an alternative to the commonly used polymer additive. Biopolymers, derived from biological sources, are fully biodegradable. In contrast to traditional polymers such as polyacrylic acid, which contain environmentally harmful components, xanthan gum is gaining attention as an eco-friendly material due to its minimal toxicity and environmental impact. Test conditions with similar workability were established through slump tests, and the rheological characteristics were assessed using a laboratory pressurized vane shear test apparatus. The experiments demonstrated that, despite exhibiting similar workability, the peak strength in the flow curve decreased with increasing the content of xanthan gum. Consequently, a correlation between the xanthan gum content and peak strength was established. Replacing the traditional polymers with xanthan gum could enable stable EPB shield TBM operation by reducing equipment load, in addition to offering environmental benefits.

• Applied Chemistry for Engineering
• /
• v.33 no.2
• /
• pp.173-178
• /
• 2022

A lateral flow immunoassay (LFIA) method using carbon nanodot@silica as a signaling material was developed for analyzing the concentration of retinol-binding protein 4 (RBP4), one of the lung cancer biomarkers. Instead of antibodies mainly used as bioreceptors in nitrocellulose membranes in LFIA for protein detection, aptamers that are more economical, easy to store for a long time, and have strong affinities toward specific target proteins were used. A 5' terminal of biotin-modified aptamer specific to RBP4 was first reacted with neutravidin followed by spraying the mixture on the membrane in order to immobilize the aptamer in a porous membrane by the strong binding affinity between biotin and neutravidin. Carbon nanodot@silica nanoparticles with blue fluorescent signal covalently conjugated to the RBP4 antibody, and RBP4 were injected in a lateral flow manner on to the surface bound aptamer to form a sandwich complex. Surfactant concentrations, ionic strength, and additional blocking reagents were added to the running buffer solution to optimize the fluorescent signal off from the sandwich complex which was correlated to the concentration of RBP4. A 10 mM Tris (pH 7.4) running buffer containing 150 mM NaCl and 0.05% Tween-20 with 0.6 M ethanolamine as a blocking agent showed the optimum assay condition for carbon nanodot@silica-based LFIA. The results indicate that an aptamer, more economical and easier to store for a long time can be used as an alternative immobilizing probe for antibody in a LFIA device which can be used as a point-of-care diagnosis kit for lung cancer diseases.

• Clean Technology
• /
• v.26 no.2
• /
• pp.109-115
• /
• 2020

Over the last 3 years, the global food 3D printing market has grown at an average annual rate of 31.5% and has shown an industry size that reached about U$ 9.46 billion. Food 3D printing technology has the advantage of being utilizable in diverse ranges because it enables free design of existing foods so that foods can be produced according to individuals' tastes and purposes. Many countries around the world are producing food 3D printers to release trial products such as foods employing the advantages of food 3D printing. They are also attempting to apply food 3D printing in various fields such as combat rations, space rations, restaurants, liquid foods, foods for the elderly, diets for patients, and baby foods. Whereas the 3D printing market, which has a high growth potential and is expected to continue to expand in size, is highly likely to become a blue ocean, not only is food 3D printing technology small in South Korea, but also the overall ratio of 3D printing utilization and the scale of the relevant industry are small. This is attributable to the fact that South Korea has problems such as insufficient institutionalization compared to developed countries and delays in the development of standardized domestic materials. Therefore, this paper is intended to inform the necessity of food 3D printing and describe food 3D printing technology and food 3D materials in order to obtain the additional effect of vitalizing the South Korean food 3D printing market.

• Korean Journal of Food Science and Technology
• /
• v.37 no.4
• /
• pp.525-531
• /
• 2005

Quality characteristics of ogapiju prepared by adding different raw materials such as Acanthopanax(0, 0.1, 0.25, 0.5%), Ganoderma lucidum(0, 0.05%), pine needle (0, 0.05%), and red ginseng(0, 0.05%) were evaluated by chemical analyses and sensory evaluation. Total organic acid contents of samples containing ogapi and other medicinal herbs were higher than that of control group. Major free amino acid was histidine. Contents of total amino acid and free sugar were highest in sample C (Acanthopanax 0.1, G. lucidum 0.05, pine needle 0.50, red ginseng 0.05%). In each sample 31-49 volatile components were identified by solid-phase microextraction method, and 42 components were detected by sniff-test using GC-olfactometry. Ogapiju showed higher content of ${\alpha}-copaene$ than control group ${\alpha}-Pinene$, camphene, ${\beta}-pinene$, sabinene, ${\alpha}-terpinene,\;{\gamma}-terpinene$, p-cymene, terpinolene, ${\alpha}-thujone,\;{\beta}-thujone,\;{\alpha}-terpineol$, carvone, and ${\beta}-ionone$ were not identified in control group. Volatile composition of ogapiju was characterized by higher amount of terpenoids. Green and herbaceous note was stronger in ogapiju than control group. Sensory evaluation indicated that good taste and palatability were highest in sample C.

• Korean Chemical Engineering Research
• /
• v.61 no.3
• /
• pp.419-425
• /
• 2023

This paper presents the research results of analyzing the high-temperature corrosion characteristics of three currently commercialized heat exchanger tube materials under actual operating conditions of a biomass power plant. In order to precisely analyze the high-temperature corrosion characteristics of these materials, a high-temperature corrosion evaluation device was installed in the power plant equipment, which allows for adjusting the surface temperature of the heat exchanger tubes. Experiments were conducted for approximately 300 hours under various temperature and operating conditions. In this study, the commercialized heat exchanger tube materials used were SA213T12, SA213T22, and SA213T91 alloys. In order to objectively analyze the high-temperature corrosion characteristics of each material, an international standard-based process to remove corrosion products was applied to obtain the weight change of the specimens, and the average thickness loss and corrosion rate were derived. Thus, the high-temperature corrosion results for each condition were quantitatively compared and analyzed. In addition, in order to increase the reliability of the high-temperature corrosion evaluation method introduced in this study, the surface and cross-sectional corrosion of the specimens were confirmed by using scanning electron microscopy and energy-dispersive X-ray analysis. Based on these analysis results, it was found that the corrosion resistance of the commercial heat exchanger materials increases as the content of chrome and nickel in the composition increases. Additionally, it was found that the corrosion phenomenon is rapidly accelerated as the surface temperature increases. Finally, the replacement period (lifetime) of the heat exchanger tubes under each condition could be inferred through this study.