• Proceedings of the Safety Management and Science Conference
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• 2007.04a
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• pp.161-171
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• 2007

The purpose of this study collected and analyzed their opinions to found solutions for reducing safety accidents since it is important to educate the students to recognize the importance of safety. We surveyed 350 students from mechanical and metal engineering departments of an engineering high school located in Seoul, and divided them in two categories and asked them about prevention of safety accidents in laboratories. Educational factors found that further directions and educations are needed for the students as to emergency measures in case of safety accidents. Safety education before laboratory classes in crucial, helpful and effective for prevention of safety accidents. Facility factors that further education is needed for students who don't experiments in orderly manner.

• Journal of the Korean institute of surface engineering
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• v.34 no.2
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• pp.115-124
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• 2001

Gas wiping process of continuously hot-dip galvanized coating on steel strip has noise and coating problems. To improve the qualify of product, characteristics of air flow on the steel surface must be investigated. In this paper, fluid dynamic model of the gas flow is setup and solved numerically using STAR-CD. The effects of edge baffle, distance between steel plane edge and baffle, inlet pressure, and gap between air knife and strip steel surface are investigated, and it is concluded that edge baffle can reduce over-coating and edge built-up.

• Journal of the Korean Ceramic Society
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• v.56 no.1
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• pp.77-83
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• 2019

MgO-C refractories are used in basic furnaces and steel ladles due to their many desirable properties, such as excellent thermal shock resistance via low thermal expansion, and high thermal conductivity. However, the mechanical and thermal properties of the refractory continuously deteriorate by spalling phenomena and pore generation due to the oxidation of graphite, used as a carbon source, indicating that the characteristics and performance of MgO-C refractories need to be improved by using a new material or composition. In this study, the use of a Hertzian indentation test as a method for determining the damage and fracture behavior of an MgO-C refractory is described. The results highlight that Hertzain indentation tests can be one of the important evaluation tools for quasi-plastic damage accumulation of MgO-C refractories during falling process of scrap metal.

• Corrosion Science and Technology
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• v.6 no.3
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• pp.128-132
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• 2007

For a quantitative inspection on the performance of weathering steel bridges, we have investigated the relationship between the corrosion rate and the composition of the rust layers formed on weathering steel bridges located in various environments in Japan and applied a protective ability index (PAI) to the bridges. The corrosion rates were clearly classified by the PAI, ${\alpha}/{\gamma}*$ and sub index of $({\beta}+s)/{\gamma}*$, where $\alpha$, \gamma*, $\beta$ and s are the mass ratio of crystalline $\alpha-FeOOH$, the total of $\gamma$-FeOOH+ $\beta$-FeOOH + the spinel-type iron oxide (mainly $Fe_3O_4$), $\beta-FeOOH$ and spinel-type iron oxide, analyzed by powder X-ray diffraction, respectively. In the case of ${\alpha}/{\gamma}$*>1, the rust layer works protective enough to reduce the corrosion rate less than 0.01 mm/y. The sub index $({\beta}+s)/{\gamma}*$<0.5 or >0.5 classifies the corrosion rate of the non-protective rust layers, therefore the former state of the rust layer terms inactive and the latter terms active. The quantitative inspection of a weathering steel bridge requires a performance-inspection (PI) and periodical deteriorationinspections (DI). The PI can be completed by checking of the PAI, ${\alpha}/{\gamma}*$. The DI on the weathering steel bridges where deicing salt is sprinkled can be performed by checking the PAI, $({\beta}+s)/{\gamma}*$.

• Korean Journal of Materials Research
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• v.13 no.10
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• pp.683-690
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• 2003

The high strength low alloy(HSLA) steels microalloyed with Nb, Ti and V have been widely used as the automobile parts to decrease weight of vehicles. The effects of process conditions are investigated in the aspects of the precipitation behavior and the mechanical properties of HSLA steel microalloyed with Nb and Ti using TEM, SANS and mechanical testing. When Ti was added to a 0.07C-1.7Mn steel which was coiled at $500^{\circ}C$, the specimen revealed the property of higher tensile strength of 853.1 MPa and the stretch-flangeability of 60%. The stretch-flangeability was increased up to 97.8% for coiling temperature above $700^{\circ}C$. The precipitation hardening cannot be achieved in the 0.045C-1.65Mn steel which was the lower density of fine precipitates. However, the 0.07C-1.7Mn steels containing Nb and/or Ti which was coiled at X$/^{\circ}C$ have a high precipitates density of $2${\times}$10^{ 5}$/$\mu$㎥. The high strength of these steels was attributed to the precipitation hardening caused by a large volume froction of (Ti, Nb)C precipitates with a size below 5 nm in ferrite matrix.

• Journal of Korean Society on Water Environment
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• v.40 no.1
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• pp.19-35
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• 2024

The global pandemic, coronavirus disease caused by Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has led to the implementation of wastewater surveillance as a means to monitor the spread of SARS-CoV-2 prevalence in the community. The challenging aspect of establishing wastewater surveillance requires a well-equipped laboratory for wastewater sample analysis. According to previous studies, RT-PCR-based molecular tests are the most widely used and popular detection method worldwide. However, this approach for the detection or quantification of SARS-CoV-2 from wastewater demands a specialized laboratory, skilled personnel, expensive instruments, and a workflow that typically takes 6 to 8 hours to provide results for a few samples. Rapid and reliable alternative detection methods are needed to enable less-well-qualified practitioners to set up and provide sensitive detection of SARS-CoV-2 within wastewater at regional laboratories. In some cases, the structural and molecular characteristics of SARS-CoV-2 are unknown, and various strategies for the correct diagnosis of COVID-19 have been proposed by research laboratories. The ongoing research and development of alternative and rapid technologies, namely RT-LAMP, ELISA, Biosensors, and GeneXpert, offer a wide range of potential options not only for SARS-CoV-2 detection but also for other viruses. This study aims to discuss the effective regional rapid detection and quantification methods in community wastewater.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.24 no.2
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• pp.229-237
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• 2014

Objectives: This study intends to determine the current status of management of personal protective equipment fume hoods in university laboratories. Methods: A walk-through survey of 402 labs in Gyeongbuk Province and Daegu Metropolitan City were carried out between May 2009 and July 2010. Respectively, 348 and 54 laboratories were examined in Gyeongbuk Province and Daegu. Results: In size, labs serving over 15,000 student made up the majority with 276(66.4%). In terms of major, engineering labs were the highest in number with 100(24.9%). As to personal protective equipment, a gas mask and a dust mask were available in 17.8% and 14.3% of the labs, respectively, but 68.9% of labs were equipped with protective goggles. Meanwhile, only 12.7% of labs had separate protective equipment storage boxes. About 60% of the labs had installed a fume hood, of which the average capture velocity was 0.37 m/sec. Conclusions: For toxic substances, the labs are obliged to provide personal protective equipment in in accordance with the Occupational Safety and Health Act. In addition, the capture velocity of fume hoods must be in strict compliance in order to prevent occupational diseases due to toxic chemicals.

• Journal of the Korean Magnetics Society
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• v.15 no.2
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• pp.72-75
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• 2005

The profiles of the second-order higher harmonics during B-H hysteresis loop have been measured as functions of the tensile stress in grain-oriented $3.2{\%}$ Si steels. The observed harmonics profiles have been analyzed in terms of the nonlinear, asymmetric magnetization which reflects the domain reorientation under the field. The field interval of the second-order higher harmonics is related to the nucleation and annihilation fields and a measurement method for the magnetostriction is proposed using the harmonics profiles under tensile stress.

• Korean Journal of Metals and Materials
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• v.47 no.6
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• pp.331-337
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• 2009

To lower the annealing temperature and the deviation of the mechanical properties of bake hardening steels, high purity steels were investigated. The steels were characterized by treating at low recrystallization temperature. It was confirmed that the strengthening originated from the solid solution of carbon and the ferrite grain refinement by fine MnS precipitates as carbon and sulfur contents increased in high purity steels. However, it was observed that there was no more increase of strength in steels containing over 40 ppm of carbon. It was considered that the excess carbon formed either the carbon cluster or the low temperature unstable carbides which had the negligible effect on the strengthening because they were reported to be highly coherent with the matrix. The carbon cluster and unstable carbides could be transformed to the stable cementite during bake hardening treatment. MnS was not observed in the high purity steel containing 5 ppm S, resulting in very coarse recrystallized grains and good ductility. As sulfur content increased, the recrystallized grain size decreased due to the formation of the fine MnS precipitates.

• Fire Science and Engineering
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• v.33 no.1
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• pp.130-137
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• 2019

In this study, the acoustic characteristics of 13 types of emergency broadcasting speakers were tested under the test set-up of UL 2043 and compared. When the sound pressure level of 1 W speakers was compared with speakers with a 15 W output, the SPL of the 15 W speakers was approximately 20 dB higher in some frequency bands. Loudness analysis showed that people can recognize emergency sound from a 15 W speaker twice as loud as the emergency sound from 1 W speakers. The analysis results on the articulation index (room) had an opposite tendency with loudness results, meaning that small speakers can generate clearer sound. Therefore, it is necessary to improve emergency broadcasting speakers to generate louder and clearer sound. Moreover, a performance evaluation standard is needed based on the reasonable and quantitative measurements and evaluations of the acoustic characteristics of the emergency-broadcasting speakers so that a sufficient and clear sound can be generated in various spaces. In addition, it is necessary to establish standards for the clarity of emergency broadcasting in various spaces.