• Title/Summary/Keyword: engineering room

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Active Control of Noise Transmitted through Ventilation Openings of the Machinery Room of Refrigerator (무부하 압축기에 의한 냉장고 기계실 소음의 능동제어)

  • Koo, Jung Mo;Jeong, Weui Bong;Kim, Tae Hoon;Hong, Chinsuk
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.26 no.4
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    • pp.475-482
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    • 2016

  • The active control of noise generated by the compressor and transmitted out of the machine room through the windows is implemented based on the FIR filter. The machine room contains most of noise sources of electric home appliances, air-conditioners and refrigerators, for example. To actively reduce the noise from the machinery room. In this paper, the transfer function of the controller for minimization of the acoustic power transmitted through the windows is mathematically formulated. The transfer functions required for implementation of the active controller are the measured. The measurements are conducted in this initial stage under the operation of the compressor with no load. For improvement of the reliability of the transfer function of the compressor to the acoustic power, additional operational measurements are performed. The real time controller is implemented based on the FIR filter using the measured transfer functions and the performance of the active controller is estimated. Control performance is measured about 3 dB ~ 10 dB in reduction of the sound power at the peaks of the compressor noise.

  • https://doi.org/10.5050/KSNVE.2016.26.4.475 인용 PDF KSCI KPUBS HTML

Stability evaluation of room-and-pillar underground method by 3D numerical analysis model (3차원 수치해석모델을 이용한 주방식 지하공간의 안정성 평가)

  • Byung-Yun, Kang;Sanghyuk, Bang;Choong-Ky, Roh;Dongkwan, Kim
    • Journal of Korean Tunnelling and Underground Space Association
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    • v.25 no.1
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    • pp.1-11
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    • 2023

  • In this study, the stability of the room-and-pillar underground method was investigated using numerical analysis method. In-situ geotechnical investigation was conducted, and a supporting pattern was selected based on the geotechnical investigation data. For the supporting pattern, Type-1, 2, 3 were selected for each ground condition. A 3D numerical analysis model was developed for effective simulation as the room-and-pillar underground method consist of a pillar and room. As a review of numerical analysis, it was confirmed that the crown settlement, convergence, shotcrete and rock bolt were all stable in all supporting patterns. As a result of the analysis by the construction stage, it was confirmed that excessive stress was generated in the room when the construction stage of forming pillar. So, precise construction is required during the actual construction stage of the pillar formation.

  • https://doi.org/10.9711/KTAJ.2023.25.1.001 인용 PDF

A study on the excavation cycle by the drill-and-blast method for a room-and-pillar underground structure (주방식 지하구조물의 발파 굴착공정 분석 연구)

  • Lee, Chul-Ho;Hyun, Young-Hwan;Hwang, Je-Don;Choi, Soon-Wook;Kang, Tae-Ho;Chang, Soo-Ho
    • Journal of Korean Tunnelling and Underground Space Association
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    • v.18 no.6
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    • pp.511-524
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    • 2016

  • Since a room-and-pillar underground structure is characterized by its grid-type array of room and pillar, its economical efficiency can be governed by excavation sequence. In this study, the construction period by the drill-and-blast method as a excavation method for a room-and-pillar underground structure was examined. In addition, the parallel excavation sequence was considered as the main sequence of a room-and-pillar underground structure. Sequences of mucking and support installation were derived to estimate the total excavation cycle by taking the case of a road tunnel into consideration. From the excavation cycle of room-and-pillar underground structure, the relationship between available maximum and minimum numbers of jumbo drill machines depending on the number of faces in operation was suggested.

  • https://doi.org/10.9711/KTAJ.2016.18.6.511 인용 PDF KSCI

A Study on the Environmental Performance Level Measurement in the Lecture Room during Winter Time (동계 대학강의실 환경성능수준 측정에 관한 연구)

  • Ahn, Tae-Kyung
    • Journal of the Korean Institute of Educational Facilities
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    • v.25 no.2
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    • pp.3-9
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    • 2018

  • This study is designed to measure the indoor environment and research on the environmental situation in the lecture room where the lecture is conducted during the winter time in order to understand the level of environment in the lecture room and then suggest the method of improving the environment in the lecture room in the future. The findings are as follows. First, the number of ventilation measured at Lecture Room 1 was 1.2 times/hour while that at Lecture Room 2 was 2.2 times/hour. Second, the lighting at Lecture Room 1 and 2 was 650~700 lux while the noise at Lecture Room 1 and 2 was not more than 60dB. Third, Group 1 and Group 2 felt in the same way that the air quality in the lecture room was not good when the air quality was measured in 30 minutes after the start of lecture. Fourth, both Group 1 and Group 2 showed the lowered concentration on the class in 30 minutes after the start of the class when the room was heated. But Group 1 got less drop in the concentration when they was put in the non-heated room. Fifth, As for the change in the carbon dioxide volume during lecture, the carbon dioxide volume in the room where the windows was closed rose 1,000~1,400ppm from that at the time of start, thus showing that the indoor air quality got worsened. In addition, it is hard to control the indoor temperature due to the heating and non-heating. Accordingly, it is necessary to get the heating system which can make the ventilation in order to keep the environmental level in the lecture room to a certain level and keep the proper indoor temperature.

  • https://doi.org/10.7859/kief.2018.25.2.003 인용 PDF