• Journal of Environmental Impact Assessment
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• v.30 no.4
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• pp.187-202
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• 2021

This study examined the effectiveness of wind corridor construction by analyzing the thermal environment, cold air generation, ventilation, and geographical characteristics to improve urban thermal environment and establish the basis for specialized strategy in Changwon-si, Gyeongsangnam-do. Using spatial analysis and remote sensing techniques, surface temperature, land cover and land use, wind field, and slope were measured and through this, a wind corridor analysis model was constructed. As a result of the analysis as of 2020, Changwon-si generally has land cover characteristics that are advantageous for the generation of cold air, but the temperature in most urban areas is the highest, and the temperature in areas such as north Changwon area, Jinbukmyeon, Ung-dong, and Ungcheon-dong are relatively high. There was a typical trend of high average wind speed in mountain regions and low average wind speed in urban areas. Accordingly, the north Changwon area, the former Changwon downtown area, the Hogye-ri and Pyeongseong-ri areas, and the Changpo Bay area are derived as vulnerable areas to thermal environment, and various measures to reduce temperature and improve air quality that the inflow of cold air into the area considering the characteristics of each area and securing wind ventilation between the surrounding mountains, reservoirs, and park areas were proposed.

• Journal of the Society of Naval Architects of Korea
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• v.59 no.4
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• pp.207-213
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• 2022

LNG CCS which is a special type of cargo hold operated at -163℃ for transporting liquefied LNG is composed of a primary barrier, plywood, insulation panel, secondary barrier, and mastic. Currently, glass fiber is used to reinforce polyurethane foam. In this paper, we evaluated the possibility of replacing glass fiber-reinforced polyurethane foam with basalt fiber-reinforced polyurethane foam. We conducted a thermal conductivity test to confirm thermal performance at room temperature. To evaluate the mechanical properties between basalt and glass-fiber-reinforced polyurethane foam which is fiber content of 5 wt% and 10 wt%, tensile and an impact test was performed repeatedly. All of the tests were performed at room temperature and cryogenic temperature(-163℃) in consideration of the temperature gradient in the LNG CCS. As a result of the thermal conductivity test, the insulating performance of glass fiber reinforced polyurethane foam and basalt fiber reinforced polyurethane foam presented similar results. The tensile test results represent that the strength of basalt fiber-reinforced polyurethane foam is superior to glass fiber at room temperature, and there is a clear difference. However, the strength is similar to each other at cryogenic temperatures. In the impact test, the strength of PUR-B5 is the highest, but in common, the strength decreases as the weight ratio of the two fibers increases. In conclusion, basalt fiber-reinforced polyurethane foam has sufficient potential to replace glass fiber-reinforced polyurethane foam.

• Journal of Environmental Impact Assessment
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• v.32 no.6
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• pp.473-487
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• 2023

Korea's multi-purpose dams, which were constructed in the 1970s and 1980s, have a single outlet located near the bottom for hydropower generation. Problems such as freezing damage to crops due to cold water discharge and an increase the foggy days have been raised downstream of some dams. In this study, we analyzed the effect of water intake depth on the reservoir's water temperature stratification structure and outflow temperature targeting Hapcheon Reservoir, where hypolimnetic withdrawal is drawn via a fixed depth outlet. Using AEM3D, a three-dimensional hydrodynamic water quality model, the vertical water temperature distribution of Hapcheon Reservoir was reproduced and the seasonal water temperature stratification structure was analyzed. Simulation periods were wet and dry year to compare and analyze changes in water temperature stratification according to hydrological conditions. In addition, by applying the intake depth change scenario, the effect of water intake depth on the thermal structure was analyzed. As a result of the simulation, it was analyzed that if the hypolimnetic withdrawal is changed to epilimnetic withdrawal, the formation location of the thermocline will decrease by 6.5 m in the wet year and 6.8 m in the dry year, resulting in a shallower water depth. Additionally, the water stability indices, Schmidt Stability Index (SSI) and Buoyancy frequency (N²), were found to increase, resulting in an increase in thermal stratification strength. Changing higher withdrawal elevations, the annual average discharge water temperature increases by 3.5℃ in the wet year and by 5.0℃ in the dry year, which reduces the influence of the downstream river. However, the volume of the low-water temperature layer and the strength of the water temperature stratification within the lake increase, so the water intake depth is a major factor in dam operation for future water quality management.

• The Journal of the Convergence on Culture Technology
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• v.9 no.6
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• pp.319-327
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• 2023

This study analyzes the risks of explosions of small LPG storage tanks installed at highway rest areas. For this purpose, the ranges of the effect of thermal radiation and overpressure caused by the BLEVE(Boiling Liquid Expansion Vapor Explosion)and VCE(Vapor Cloud Explosion) of a 2900-kg small LPG storage tank installed at highway rest areas were quantitatively evaluated by applying the Areal Location of Hazardous Atmospheres program. The ranges of influence of the derived explosion overpressure and thermal radiation were found to have a maximum radii of 336 m and 423 m, respectively. The study determined that those within 269 m could be severely injured by an explosion overpressure of 3.5 psi, and fatalities from thermal radiation of 10 kw/m² could occur within 192 m of the exploded storage tank. The safety management plan for the LPG storage tank was discussed while considering the auxiliary facilities of highway rest areas and the extent of the damage impact. These research results will help improve safety accident prevention regulations considering the environment and facilities of the rest areas as well as the safety management of small LPG storage tanks installed at highway rest areas.

• Proceedings of the KSR Conference
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• 2005.05a
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• pp.491-497
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• 2005

Brake system is indispensible functional part to the transportation machines such as railroad cars, and all of industrial machines. It is mechanical element to stop the movement or slow the speed, transforming kinetic energy of motion object into thermal energy through solid friction. According that recently the railroad cars have become high-speed, the technique in braking domain to secure the overall braking effort is making rapid progress. In particular, material development and manufacturing process are so important to secure friction performance, which is the core in braking performance of mechanical brake units. Wear of brake disk could mainly result in the diminishment of its life span due to thermal cracking, so the endurance against high temperature is required. On the other hand, in this case, the problem is that the side wear of pad, relative material is slightly increased because of enlargement of plastic deformation. It is necessary, therefore, to develop a disk material that will be used in the Tilting System mechanical brake units. The purpose of this paper is to make a study prior to developing brake disk of Tilting Train travelling at 200km/h and to propose the component of brake disk. Accordingly, I will conduct sufficient researches on technical documents of brake disk, that are basic documentations, analyze an impact on components, and further, considering braking degree of train, study for the basic proposal on brake disk's component of the train travelling at 200km/h, which has relatively minor influence of heat stress and maintains the friction. In this respect, I would like to investigate friction characteristics between disk and relative friction material via Test on some possible test segments, analyze and propose friction performance, temperature impact and so forth coming from the contact with pad, relative material to demonstrate the friction characteristics.

• Journal of the Korean Vacuum Society
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• v.6 no.3
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• pp.181-186
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• 1997

Time-of-flight impact-collision ion scattering spectroscopy (TOF-ICISS) was applied to study the geometrical structure of epitaxially grown MgO layers on a TiC(001). The hetero-epitaxial MgO layer was able to be deposited by thermal evaporation of magnesium onto the TiC(001) surface and subsequent exposure of oxygen at room temperature. A slight heating of the substrate at around $300^{\circ}C$ was necessary to overcome a thermal barrier for the ordering. The well-ordered MgO structure was confirmed with the 1$\times$1 LEED pattern. TOF-ICISS was useful in studying interface structure between oxide and substrate. The results revealed that the MgO layer is formed at the on-top sites of the TiC(001) substrate and the lateral lattice constant of MgO layer is the same as that of the TiC substrate. The MgO was deposited within two layers on the most parts of the surface.

• Nuclear Engineering and Technology
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• v.52 no.5
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• pp.937-946
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• 2020

The aim in the present work is to simulate accident scenarios of AP1000 during the small-break loss-of-coolant accident (SBLOCA) and investigate the performance and behavior of automatic depressurization system (ADS) during accidents by using MIDAC (The Module In-vessel Degradation severe accident Analysis Code). Four types of accidents with different hypothetical conditions were analyzed in this study. The impact on the thermal-hydraulic of the reactor coolant system (RCS), the passive core cooling system and core degradation was researched by comparing these types. The results show that the RCS depressurization becomes faster, the core makeup tanks (CMT) and accumulators (ACC) are activated earlier and the effect of gravity water injection is more obvious along with more ADS valves open. The open of the only ADS1-3 can't stop the core degradation on the basis of the first type of the accident. The open of ADS1-3 has a great impact on the injection time of ACC and CMT. The core can remain intact for a long time and the core degradation can be prevent by the open of ADS-4. The all results are significant and meaningful to understand the performance and behavior of the ADS during the typical SBLOCA.

• Steel and Composite Structures
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• v.47 no.6
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• pp.693-707
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• 2023

This article investigates the static thermo-mechanical response of anisotropic thick laminated composite plates on Visco-Pasternak foundations under various thermal load conditions (linear, non-linear, and uniform) along the transverse direction (thickness) of the plate, while keeping the mechanical load constant. The governing equations, which represent the thermo-mechanical behavior of the composite plate, are derived from the principle of virtual displacements. Using Navier's type solution, these equations are solved for the composite plate with simply supported condition. The Visco-Pasternak foundation type is included by considering the impact of the damping on the classical foundation model, which is modeled by Winkler's linear modulus and Pasternak's shear modulus. The excellent accuracy of the present solution is confirmed by comparing the results with those available in the literature. The study investigates the impact of geometric ratios, thermal expansion coefficient ratio, damping coefficient and foundation parameters on the thermo-mechanical flexural response of the composite plate. Overall, this article provides insights into the behavior of composite plates on visco-Pasternak foundations and may be useful for designing and analyzing composite structures in practical applications.

• Analytical Science and Technology
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• v.37 no.5
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• pp.280-294
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• 2024

This study introduces a novel analytical method for the assessment of pralsetinib impurities and degradation products (DPs), addressing critical gaps in existing methodologies. This research aims to develop a robust HPLC method for impurity analysis, characterize degradation products using LC-MS, and evaluate the environmental impact of the method. The study began by optimizing HPLC conditions with various columns and buffers, ultimately achieving successful separation using an XBridge^® RP-C18 column with ethanol as solvent A and 50 mM formic acid at pH 2.9. This setup provided excellent peak resolution and symmetry, essential for reliable stability studies. The developed HPLC method was then adapted for HPLC-MS/MS, enhancing sensitivity and detection efficiency of DPs. Stress degradation studies of pralsetinib under different conditions (acidic, basic, oxidative, thermal, and photolytic) revealed significant degradation under acidic (29.3 %) and basic (21.5 %) conditions, with several DPs identified. Oxidative stress resulted in 19.8 % degradation, while thermal and photolytic conditions caused minimal degradation. HPLC-MS/MS analysis identified structures of five degradation products, providing detailed insights into pralsetinib's stability and degradation pathways. Method validation followed ICH guidelines Q2(R1), confirming method's specificity, selectivity, sensitivity, linearity, accuracy, precision, and robustness. The method exhibited strong linearity with a coefficient of determination (r²) greater than 0.999 for pralsetinib and its impurities. This method advances impurity detection and DPs characterization, ensuring the quality and safety of pralsetinib. Additionally, method's environmental impact was assessed, aligning with sustainable analytical practices. These findings provide essential data on pralsetinib's stability, guiding storage conditions and ensuring its efficacy and safety in pharmaceutical applications.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.34 no.5
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• pp.181-186
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• 2024

In order to solve the problems of low strength and brittle fracture of conventional concretes, ordinary cement was used as the main material of concrete binder, and porous glass beads processed from waste glass were used as aggregates to provide lightweight and fireproof insulation, and functional organic binding additives (including polymers) were added to improve concrete strength. Additional binding agents, such as silanes, were used to produce concrete-type lightweight materials with a specific gravity lower than water. The resulting materials thus manufactured have solved the problems of low work-ability and brittle fracture of conventional (ceramic) concretes, and exhibited excellent mechanical and thermal properties, with good fireproofing properties and low thermal conductivity at high temperatures. In addition, it can be molded into a certain space like conventional concrete, processed into bricks or thin boards in molds, or applied like paints, so it is believed that it can be applied to various structural materials.