• Nuclear Engineering and Technology
• /
• v.26 no.4
• /
• pp.471-483
• /
• 1994

A sodium fire facility with a test chamber of 1.7㎥ volume was constructed and operated to carry out experiments of sodium fires such as pool, spray, and columnar fires which might take place in sodium-related facilities. The experimental results of pool fires showed that the increase of temperature and pressure in the test chamber was much smaller than that of spray and columnar fires even though their amount of sodium injection in the chamber was much larger compared to other types of fires. And it was found in pool fires that the temperatures of sodium pool and the gas temperature in the test chamber had been maintained much longer than other types of fires, and that the chamber pressure had come to vacuum due to depletion of the oxygen for a large amount of sodium injection in the chamber. The experimental results of spray fires showed that sprayed sodium of small particles instantly reacted with oxygen, and that its reaction heat increased gas temperature and pressure of the test chamber rapidly and decreased them shortly. And the maximum gas temperature and pressure of the test chamber in spray fires ore greatly changed according to the inlet sodium temperature in the test chamber. The characteristics of the columnar fires were almost similar to those of spray fires, but the maximum temperature and pressure of the test chamber were much smaller even for a large amount of sodium injection. And it was shown in spray and columnar fires that the temperatures at each measurement position in the test chamber were quite different due to the instantaneous sodium oxidation in comparision with pool fires. Finally, the graphex powder was proved to be a very effective extinguisher against sodium pool fires.

• Journal of the Korean Applied Science and Technology
• /
• v.38 no.4
• /
• pp.986-993
• /
• 2021

This study was aimed to investigate the improvement effects of kelp extract on the damaged hair by manufacturing hair quality improving formulation adding kelp extract and applying that in the damaged hair. With respect to the study materials, the formulation was manufactured with different strengths of kelp extract including 0, 2, 4, and 6 grams, adding perm base material. The manufactured formulation was applied to the decolored sample hair of Level 8 and its effects were measured and compared before and after its application. Tensile strength, absorbance using methylene blue, and gloss were measured as the tools to show the improvement effects of hair quality. To check the reliability of the results, statistical analysis was performed. Tensile strength showed to be increased in the Level 8 samples applied by the formulations containing 4- and 6-gram strength. Absorbance using methylene blue showed to be decreased in all the samples after the application, based on the absorbance results before and after the application. No difference was found in all the samples on the gloss. In conclusion, this study revealed that kelp extract could improve the damaged hair. Further studies are required to check the improvement effects on the damaged hair with multiple types of extracts and study methods.

• Journal of the Korea institute for structural maintenance and inspection
• /
• v.25 no.6
• /
• pp.76-83
• /
• 2021

This study examines the bending behavior of lap-spliced ultra-high-strength fiber-reinforced concrete members and evaluates the safety of the design codes for ultra-high-strength fiber-reinforced concrete structures. An experiment on a total of six beams was performed. The main variables were the fiber-inclusion and the lap-spliced length at the center of the beams. The steel fibers in a volume fraction of 2% were used, and the lap-splice lengths were determined to be 8db and 16db. As a result of the test, the specimens not reinforced with fiber lost abrupt load-bearing capacity at the lap region and did not experience yielding of the reinforcing bar. In the case of fiber-reinforced concrete, if a lap-splice length of 16db is secured, the yielding of the main reinforcing bar can be experienced, and appropriate flexural strength can be expressed. Based on the experimental results of this study, as a result of reviewing the lap-splice length calculation formulas of the current design standards and the ultra-high-strength concrete structural design recommendations, it was found that all of them were evaluated conservatively.

• Journal of the Korea institute for structural maintenance and inspection
• /
• v.25 no.6
• /
• pp.60-67
• /
• 2021

In lately, it's been developed and used a system of using deck plates as formwork in order to solve various problems caused by conventional formwork system. This system is more economical and has higher constructability than the conventional system by permanently embedding most of deck plates into the members. However, for this kind of embedded deck plates formwork system, it's been reported that it is difficult to verify filling of concrete in members like beams with narrow width and complicated rebar arrangement. In addtion, there are several problems such as corrosion of deck plates in terms of constructability and maintenance. Therefore, in this study, it is attempted to develop a removal-deck plate formwork system for beams by removing deck plates after concrete curing. The system consists of a deck plate module that acts as form, a frame preventing deformation by concrete lateral pressure, stirrup frame, and connector that combines these. As a result of this research, it is verified that it has higher constructability, efficiently prevents deformation caused by concrete lateral pressure and could be easily removed in the developed formwork system.

• Journal of the Korean Institute of Gas
• /
• v.25 no.3
• /
• pp.46-52
• /
• 2021

In this study, the on-site location identification and response system was proposed by accurately checking the location information of rescue requesters in the buildings using the smartphone Wi-Fi AP. The location server was requested to measure the strength of the Wi-Fi AP at least 25 times at 8 different building location points. And the accuracy of the position and the error range were checked by analyzing the coordinate values of the received positions. In addition, the response time was measured by changing the conditions of location information in three groups to compare the response time for saving lives with and without location information. The minimum and maximum error values for the eight cases were found to be at least 4.137 m and up to 14.037 m, respectively, with an average error of 9.525 m. Compared to the base transceiver station (BTS) based position error value of 263m, the range could be reduced by up to 93%. When the location information was given, it took 10 minutes and 50 seconds to save lives; however, when there was no location information at all, rescue process took more than 45 minutes. From this research effort, it was analyzed that the acquisition of the location information of rescuees in the building using the smartphone Wi-Fi AP approach is effective in reducing the life-saving time for on-site responses.

• Journal of Climate Change Research
• /
• v.4 no.4
• /
• pp.331-348
• /
• 2013

The frequency and intensity of abnormal climate caused by climate change is increasing in Korea. Also, the amount of damage from disaster is increasing rapidly. The research on vulnerability assessment analyzes environmentally, socially and economically vulnerable indicators and is ongoing to reduce the intensity of damage and establish adaptation policies for climate change. Therefore, in this study, we assessed vulnerability using weighting value derived by the regression equation. There are 3 evaluation items : vulnerability assessment for farmland erosion to flood, vulnerability assessment for health to heat wave, vulnerability assessment for forest fire to drought. For this study, indicators for each sectors were selected and spatial data for each sectors were established using GIS program. Results showed that vulnerability to heat wave was more affected by climate factors. On the other hand, vulnerability to flood and drought was more affected by social-economic factors. Then, to analysis efficiency of the regression analysis, vulnerability result was compared between the existing vulnerability research with no weighting applied and the vulnerability research with the influence of weighting value derived by the regression. This study showed that the regression analysis is efficient to provide practical and feasible alternatives in terms of planning climate change adaptation policies and it is expected to be utilized for vulnerability assessment in the future.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.20 no.3
• /
• pp.507-512
• /
• 2019

To study how illuminance affects cognitive ability of the elderly, the elderly's EEG, concentration, HRV and vibra image were measured in a test room with temperature $25[^{\circ}C]$, relative humidity 50[RH%] and air flow speed 0.02[m/sec] by varying illuminance to 100[lux], 300[lux], 600[lux], 1000[lux] and 1500[lux]. Ten active elderly males were selected as subjects. Experiment condition was fixed as 1met of activity amount where the subject is seated and relaxed with cloth amount of 0.7clo. As a result, 1000[lux] was found out to be the most pleasant illuminance for the elderly, because $M{\beta}$ increased by 66.35%, and $S{\alpha}$ increased by 31.57% when the elderly was under 1000[lux] of illuminance. Also, concentration under 1000[lux] increased by 8.83% compared to 100[lux], and the pattern of concentration maintained uniformly. SDNN increased by 74.94% under 1000[lux] compared to 100[lux]. Nervousness decreased by 97.23% under 1000[lux] compared to 100[lux]. Moreover, HRT notably increased and aggression remarkably decreased under illuminance of 1000[lux]. Thus, based on the fact that comfort, concentration and heart stability of the elderly reach the highest under 1000[lux], it is determined that the illuminance has to be considered foremost in designing the elderly's welfare facilities to raise their safety and level of independence.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.22 no.1
• /
• pp.511-519
• /
• 2021

Slewing bearing is applied to the transmission of rotational power of the body and turret in a special vehicle for anti-aircraft weapons that overcomes the enemy flight system approaching at low altitudes with rapid response fire. When the turret load and impact load generated when shooting are combined in performing the combat mission of a special vehicle, structural stability must be secured to achieve a successful function. Among the components of the slewing bearing, the stability of the components against the complex loads acting by the turret drive and shooting was evaluated by considering the shape and material characteristics of the ring-gear, roller, and wire-race. As a research method for stability evaluation, based on engineering theory, the strength characteristics of the components were examined by numerical calculations. Finite element analysis was performed on components using the ANSYS analysis program. The results of theoretical analysis and the results of finite element analysis were very similar. A structural stability evaluation for the slewing bearing, which was performed mainly on the analysis, confirmed that the design strength of the slewing bearing determined in the preliminary design in the early stage of localization development was sufficient.

• Tunnel and Underground Space
• /
• v.31 no.1
• /
• pp.52-65
• /
• 2021

In this study, authors analyzed the vapor cloud explosion induced by propane leak at the PEMIX Terminal, which is the propane storage facility outside of Mexico City. TNT equivalence mass for the leaked 4750 kg propane was estimated to be 9398 kg. Blast parameters such as peak overpressure, positive phase duration, and impact at 40-400 (m) away from the center of the explosion were calculated by applying TNT Equivalency Method and Multi-Energy Method. The probability of damage due to lung damage, eardrum rupture, head impact, and whole-body displacement impact by applying the probit function obtained using blast parameters was evaluated. The peak overpressure obtained using Multi-Energy Method was found to be greater than the peak overpressure obtained by applying the TNT Equivalency Method at all distances considered, but it was evaluated that there was no significant difference from the points above 200 m. The peak overpressure obtained by Multi-Energy Method was computed to assess the extent of damage to the structure, and it was shown that structures within 100 m of the explosion center would collapse completely, and that the glasses of the structures 400 m away would be almost broken. The probability of death due to lung damage was shown to vary depending on a human body's position located in the propagating direction of shock wave, and if there is a reflecting surface in the immediate surroundings of a human body, the probability of death was estimated to be the greatest. The impact of shock wave on lung damage, eardrum rupture, head impact, and whole-body displacement impact was evaluated and found to affect whole-body impact < lung damage < eardrum rupture

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.21 no.12
• /
• pp.867-872
• /
• 2020

Oil storage tanks are a major structure in chemical industrial complexes. Damage to the structure due to natural disasters or poor management can cause additional damage, such as leakage of chemicals, fire, and explosion, so it is essential to understand the deformation. In this study, data on oil storage tanks were acquired using a 3D laser scanner, and various analyzes were performed for storage tank management by comparing them with design data. Modeling of the oil storage tank was performed using the data and design drawings acquired by a 3D laser scanner. An inspection of the oil storage tank was effectively performed by overlapping. In addition, cross-sectional and exploded views of the deformation were produced to generate visible data on the deformation of the facility, and it was suggested that the oil storage tank had a maximum deformation of -7.16mm through quantitative analysis. Data that can be used for additional work was obtained by producing drawings to be precisely inspected for areas with large deformation. In the future, an inspection of oil storage tanks using 3D laser scanners is quantitative and visible data on oil storage tank deformation. This will greatly improve the efficiency of facility management by rebuilding it.