• Journal of the Society of Disaster Information
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• v.19 no.2
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• pp.344-351
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• 2023

Purpose: This study aimed to evaluate the effectiveness of a dielectric barrier discharge (DBD) plasma module for sterilizing airborne bacteria in indoor spaces and measure the concentration of ozone generated during plasma discharge. Method: The DBD plasma module was installed in a 76m³ space, and air samples were collected under various discharge times to compare the reduction of airborne bacteria. Result: The results showed a significant decrease in airborne bacteria, ranging from 92.057% to 99.999%, with an average ozone concentration of 0.04 ppm, below the reference value. Conclusion: The study suggests that plasma discharge can be used as a means of preventing the spread of airborne bacteria and viruses, while ensuring safety for human exposure.

• Journal of the Korea institute for structural maintenance and inspection
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• v.27 no.2
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• pp.25-32
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• 2023

In this study, a double wall system is introduced, which was invented to simplify the complicated manufacturing process of the existing precast concrete (PC) double wall systems and to remove defects such as laitance that may occur during the production of concrete panels. An experimental study was conducted to investigate the tensile resisting capacity of the steel tube which is embedded in the precast concrete panel to keep the spacing between PC panels and to prevent damage of the PC panels during transportation and casting concrete onsite. The experiment was planned to determine the detail of effective steel tube connection considering the steel plate treatment method according to the formation of the opening, the presence of embedded concrete, and the reinforcement welding for additional dowel action as key variables. As a result, the ultimate tensile strength increased by 20-30% compared to the control specimen (ST) except for the steel tube specimen (ST_CP) which has steel plates bent inward at the end part of the steel tube. Since the specimen (ST_CON) filled with concrete inside the control specimen has no additional process and cost for the steel tube connections compared to the control specimen during the production of the developed double wall system, it is determined to be the appropriate detail of steel tube connection.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.11
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• pp.683-692
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• 2020

A joint displacement resistance evaluation method for selecting waterproofing materials in railway bridge decks is proposed. The displacement range for an evaluation is determined by finite element method (FEM) analysis of a load case based on an existing high-speed PSC Girder Box railroad bridge structure. The FEM analysis results were used to calculate the minimum joint displacement range to be applied during testing (approximately 1.5 mm). For the evaluation, four commonly used waterproofing membrane types, cementitious slurry coating (CSC), polyurethane coating system (PCS), self-adhesive asphalt sheet (SAS), and composite asphalt sheet (CAS), were tested, with five specimens of each membrane type. The joint displacement width range conditions, including the minimum displacement range obtained from FEM analysis, were set to be the incrementing interval, from 1.5, 3.0, 4.5, and 6.0 mm. The proposal for the evaluation criteria and the specimen test results demonstrated how the evaluation method is important for the sustainability of high-speed railway bridges.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.36 no.8
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• pp.929-934
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• 2012

This study was carried out to analyze the dynamic characteristics of laser tailor-welded blanks (TWBs) made of dissimilar materials. The analysis was performed using Hyper Works 10.0 with Solver LS-DYNA v.971. 2D-Shell was used as the modeling element, and the number of elements and nodes was 35,641 and 36,561, respectively. The impact speed was 10 km/h. To analyze the impact characteristics according to the height of the weld line for the upper and lower parts of the center pillar, the length of the lower part was set as 300 and 400 mm. When the lower part was made of SPFC980 steel with a length of 300 mm, the deformation was the smallest and the absorbed energy of the impact force was the largest. On based the lower part of center pillar, the position of TWB shows the shorter and the better value. In other words, the performance depended on the proportion of the upper part made of high-strength SABC1470 steel. A lower part made of SPFH590 steel showed large deformation. In contrast, a lower part made of SPFC980 steel showed significantly lesser deformation. Therefore, the impact performance of a lower part made of SPFC980 steel with a length of 300 mm showed the best analysis result.

• Journal of Korean Society of Disaster and Security
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• v.12 no.2
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• pp.47-56
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• 2019

Recently, in order to overcome the difficulty of entering a fire source due to the occurrence of a large amount of smoke in the event of a fire in a parking lot, it has used that a method of discharge smoke using air supply, exhaust fans and jet fans installed for ventilation of parking lots. In this study, the variation of flow in the smoke layer was observed using CCTV under two conditions, in which only the air supply fan operates and the manned fan operates together, and the temperature around the plume was compared to Albert eq. to assess its suitability as a parking lot ventilation performance evaluation method. As a result, it was found that the smoke layer could be disturbed if the Jet Fan was operated at the same time, which could lead to the possibility of an initial evacuation disturbance. However, the additional operation of the Jet Fan has been confirmed by the observation CCTV that the emission performance is improved, which is believed to help conduct the suppression operation. The temperature around the plume was measured and compared to Alpert eq, and was analyzed to be about $2^{\circ}C$ lower at the center axis of the plume and $9.0^{\circ}C$ higher at 8 m in the direction of the discharge of smoke. The results of temperature measurements around the plume were lower than the maximum temperature expected in AS 4391 and did not exceed the expected temperature risk caused by the experiment. As with these results, the temperature risk from the progression of hot smoke tests is foreseeable, so it will be available as one of the general evaluation methods for assessing smoke control performance in a parking lot without relevant criteria.

• Journal of the Korea institute for structural maintenance and inspection
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• v.23 no.4
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• pp.96-102
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• 2019

When GGBFS(Ground Granulated Blast Furnace Slag) with high blaine is incorporated in concrete, compressive strength in the initial period is improved, but several engineering problems arise such as heat of hydration and quality control. In this paper, compressive strength and durability performance of concrete with 3,000 Grade-low fineness slag are evaluated. Three conditions of concrete mixtures are considered considering workability, and the related durability tests are performed. Although the strength of concrete with 3,000 Grade slag is slightly lower than the OPC(Ordinary Portland Cement) concrete at the age of 28 days, but insignificant difference is observed in long-term compressive strength due to latent hydration activity. The durability performances in concrete with low fineness slag show that the resistances to carbonation and freezing/thawing action are slightly higher than those of concrete with high fineness slag, since reduced unit water content is considered in 3,000 Grade slag mixture. For the long-term age, the chloride diffusion coefficient of the 3000-grade slag mixture is reduced to 20% compared to the OPC mixture, and the excellent chloride resistance are evaluated. Compared with concrete with OPC and high fineness GGBFS, concrete with lower fineness GGBFS can keep reasonable workability and durability performance with reduced water content.

• Journal of Bio-Environment Control
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• v.31 no.4
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• pp.438-443
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• 2022

In this study, the lateral loading test was performed to analyze structural performance of multi-span plastic greenhouse through full-scale experiment and numerical analysis. In order to analyze the lateral stiffness and stress, we installed 9 displacement sensors and 19 strain gauge sensors on the specimen, respectively, and load of l mm per minute was applied until the specimen failure. In the comparison between the full-scale experiment and the structural analysis results of a multi-span greenhouse with venlo-type roof according to bracing installation, there was a large difference in the lateral stiffness of the structure. By installing a brace system, the lateral stiffness measured near the side elevation of the specimen increased by up 44%. As the bracing joint used in the field did not secure sufficient rigidity, the external force could not be transmitted to the entire structure properly. Therefore, it is necessary to establish a bracing construction method and design standards in order for a greenhouse to which bracing applied to have sufficient performance.

• Journal of Aerospace System Engineering
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• v.16 no.4
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• pp.60-67
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• 2022

An Electro-Optical Tracking System (EOTS) is an electric optical system with EO/IR cameras, laser sensors, and an IMU. The EOTS calculates coordinates of targets, using attitude and acceleration measured by the IMU. In particular for an armed aircraft, the performance of the weapon system depends on how quickly and accurately it acquires the target coordinates. The IMU should be operated after alignment is complete, to meet the coordinate accuracy required by the weapon system so the initial stabilization time of the IMU should be reduced, by quickly measuring the attitude and acceleration. Alignment is the process of determining the initial attitude by resolving the attitude error of the IMU, and the IMU of mission equipment such as an airborne EOTS, uses velocity matching based on the velocity from GPS/INS for aircraft navigation. In this paper, a method is presented to improve the transfer alignment performance of the airborne EOTS, by maneuvering aircraft and the mission equipment. First, the performance factor of the alignment was identified, as a heading error through the velocity matching model and simulation results. Then acceleration maneuvers and attitude changes were necessary, to correct the error. As a result of flight tests applied to an EOTS on a OOO aircraft system, the transfer alignment performance was improved as the duration time was decreased, by more than five times when the aircraft accelerated by more than 0.2g and the EOTS was moving until 6.7deg/s.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.42 no.2
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• pp.197-208
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• 2022

The existence of shallow bedrock and the desire to use underground space necessitate the use of blasting methods. The standard blasting method under water after drilling is associated with certain technical difficulties, including reduced detonation power, the use of a fixed charge per delay, and decoupling. However, there is no blasting method to replace the existing blasting method. In this paper, a dry hole charged with ANFO blasting is assessed while employing a dry hole pumping system to remove water from the drill borehole. Additional standard blasting is also utilized to compare the blasting performances of the two methods. The least-squares linear regression method is adopted to analyze the blasting vibration velocity quantitatively using the measured vibration velocity for each blasting method and the vibration velocity model as a function of the scaled distance. The results show that the dry hole charged with ANFO blasting will lead to greater damping of the blasting vibration, more energy dissipation to crush the surrounding rock, and closer distances for the allowable velocity of the blasting vibration. Also, standard blasting shows much longer influencing distances and a wider range of the blasting pattern. The pilot test confirms the blasting efficiency of dry hole charged with ANFO blasting.

• The Korean Journal of Nuclear Medicine Technology
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• v.16 no.2
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• pp.149-155
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• 2012

Purpose : Serum insulin levels are useful indicator which of reflecting the function of insulin secretion in pancreatic ${\beta}$ cell and diagnosis of diabetes, differentiating the cause of impaired glucose tolerance. Insulin measurement kits have shown some differences in many ways such as test methods as well as quality control. The purpose of this study was to evaluate the diagnostic performance of seven manufacturing companies commercial kits. Materials and Methods : The values of insulin measured by three manufacturing companies (Biosource, Siemens, TFB) with 59 samples in August 2009 were compared with those measured by four manufacturing companies (Immunotech, Izotope, BNIBT, Cisbio) with 68 samples in December 2011. We evaluated precision, recovery rate, dilution test and correlation of serum insulin measurement using seven manufacturing company kits. Statistical program SPSS 12.0 was used for the verification of results. Results : The coefficients variation of the precision on all seven different kits were showed within 5.0%. Recovery rate of Biosource, Siemens, TFB kits on three different levels showed 94.2~103.7%, 99.0~104.6%, 99.7~107.6% respectively. Immunotech, Izotope, BNIBT, Cisbio were 93.5~99.1%, 91.4~99.1%, 99.2~131.0%, 84.8~102.3% respectively. There was strong correlation between the measurement of insulin by Biosource kit and that by two commercial kits, Siemens (R2=0.96), TFB (R2=0.99). There was good correlation between the measurement of insulin by TFB kit and that by three commercial kits, Immunotech (R2=0.97), Izotope (R2=0.96), Cisbio (R2=0.97). In the dilution test performed with more than 200 ${\mu}IU/ml$ high concentration samples, samples with diabetes correctly was measured in all seven manufacturing kits. However, as measured with insulinoma samples TFB, Siemens, Izotope, Cisbio kits were correctly measured, but Biosource and Immunotech kits were measured 47.4 ${\mu}IU/ml$, 72.3 ${\mu}IU/ml$, respectively. Conclusion : Serum Insulin radioimmunoassay kits were showed excellent precision, correlation and good recovery rate. However, some kits were not measured correctly in the high concentration insulin values. when selecting a kit should be considered many factors that cost effectiveness, compatible for automation equipment, high performance kit, the environment for each laboratory such as reaction time and reporting time.