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수소주택 연료전지실 안전 가이드라인 개발을 위한 선행연구 분석
장희라(Hee La Jang),황인주(In Ju Hwang),이홍철(Hong Cheol Lee) 대한설비공학회 2022 대한설비공학회 학술발표대회논문집 Vol.2022 No.6
The hydrogen pilot city project, which is one of the government’s measures to realize ‘2050 carbon neutrality’, aims to reduce carbon emissions through the use of fuel cells in homes. However, when planning a fuel cell room inside a house, there is a risk of explosion so safety considerations should be sufficiently taken into account. Therefore, in this study, hydrogen leakage characteristics were identified through the analysis of previous studies related to hydrogen leakage. Based on these results, it is thought that it will be possible to suggest directions for the development of experiments and safety guidelines for the design of fuel cell room safety facilities to be applied to the fuel cell room of a hydrogen house in the future.
흡음요소 변경을 통한 MRI실의 음향성능 개선 및 변화
장희라 ( Hee-la Jang ),이현재 ( Hyun-jae Lee ),김재수 ( Jae-soo Kim ) 한국환경기술학회 2018 한국환경기술학회지 Vol.19 No.2
MRI in modern medical science is a device that generates magnetic fields to analyze and visualize signals that occur inside the human body. However, MRI causes serious noises while coils move within the device to generate a strong magnetic field and the noises can give serious physical and psychological distress to patients. For this reason, correct data concerning the acoustic characteristics of an MRI room are needed to reduce the noises generated from MRI operation and improve definition in the room; however, South Korea has had almost no relevant research. From this perspective, this study used acoustic simulation to determine acoustic performance and characteristics in four MRI rooms with totally different specifications and indoor absorption elements. Then, it determined how much the acoustic performance indexes were changed and improved by changing the finishing materials within the MRI rooms. Before the improvement, the MRI rooms had very poor acoustic performance and urgently required improvement in acoustic performance. After improving indoor absorbing power by changing the finishing materials within the rooms, SPL<sub>dB</sub>(A) from 84-89.8 dB(A) to 78.9- 79.9 dB(A) and SPL at the 500Hz band dropped from 78.9-85.6 dB to 73-74.3 dB. RT improved from 0.55-1.22 sec to 0.01-0.24 sec, D50 from 40-69 % to 100 %, and RASTI from 54-80 % to 91-95 %. Ultimately, while the MRI rooms had very poor acoustic performance before the improvement, they had the SPL drop significantly, with significant improvement in D50 and the RASTI due to significantly shortened RT, after the improvement. So patients who have been examined in MRI rooms are expected to be able to get examinations in a much quiet environment with higher definition after the improvement in acoustic performance.
장희라(Hee-La Jang),송현옥(Hyun-Og Song),김재수(Jae-Soo Kim) 한국생활환경학회 2018 한국생활환경학회지 Vol.25 No.2
Magnetic resonance imaging (MRI) in modern medical science is a method of imaging by putting a person into a device generating a magnetic field to generate high frequency and analyze the signals generated from inside the body. However, MRI causes serious noises while coils move within the device to generate a strong magnetic field. These noises can give serious physical and psychological distress to patients. For this reason, various data are needed to reduce the noises generated from MRI operation; however, South Korea has had almost no relevant research. From this perspective, this study selected four MRI devices with different degrees of a magnetic field, measured noises for each source of MRI operation, and analyzed the waveform, the sound pressure level based on frequency, and the weighted sound level or dB(A). On the basis of these data, MRI operation noises were evaluated with dB(A) and NR to determine how much they affected patients. The MRI operation noises could be divided into four waveforms and most of them were extremely high in the medium-to-high frequency bands, with the exception of the WN noises. When the MRI operation noises were evaluated with dB(A), the NR curve, and PSIL, 0.3T of the magnetic field led to 57.1-64 dB(A), NR 53-62, and 1.98-3.96 m for medium sound, and 4.26-8.31 m for loud sound, with no significant effect on patients. In contrast, 1-3T of the magnetic field led to 74.4-90.9 dB(A) and NR 72-89 for Noise T1, 85.9- 91.7 dB(A) and NR 83-90 for Noise T2, 90.5-28.1 dB(A) and NR 87-98 for Noise D, 79.4-89.8 dB(A) and NR 77- 89 for Noise G, 0.06-0.65 m for medium sound, and 0.12-1.29 m for loud sound in terms of PSIL. Because of patients’ exposure to very serious noises, it is urgent to take measurements then. In particular, 1-3T of the magnetic field, which can affect patients, led to 100-1,000 Hz of grading frequency for the NR curve; therefore, it is essential to lower the noise level of this band with the objective of reducing damages from the exposure to serious noises during an MRI scan.