• Title/Summary/Keyword: ceiling value

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Experiment Evaluation for the Heavy-weight Impact Sound of Dry Double-floor System - Effect of Rubber Hardness and Ceiling Structure - (건식이중바닥구조의 중량충격음에 대한 실험적 평가 - 지지구조 및 천장구조 구성에 따른 영향 -)

  • Yeon, Junoh;Kim, Kyoungwoo;Choi, Hyunjuong;Yang, Kwanseop;Kim, Kyungho
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.23 no.1
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    • pp.34-40
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    • 2013
  • The 1st assessment(performance test) was applied to assure the floor impact sound performance for developing the dry double-floor with the change of rubber hardness of the upper panel's support and the ceiling structure of the sub-floor. Depends on the change of the rubber hardness in sub-structure, the heavy-weight sound impact value is improved up to 3 dB, and the light-weight sound impact value is moved up to 21 dB, comparing with the bare-slab. Also, the improved value for the floor impact sound conjugating with the sub-floor's ceiling was 5 dB. Based on this result, the 2nd assessment(performance test) was made the state that the rubber hardness of the sub-floor support was ranged between 50 and 70 for considering the stability of walking patients. In addition to this process, the assessment was carried out with a variety of ceiling structure applied to the dry double-floor structure with the air flow system on the sub-floor's ceiling. The result for the 2nd assessment proved that TYPEII-3 had the better sound reduction performance in the heavy-weight impact sound test than other types, and also for the light-weight impact sound TYPEII-3 had the 29 dB sound reduction performance overall. Henceforth, based on the result the research for the sound reduction performance from the floor impact sound shall be ongoing process as well as the development of a double-dry floor and a sound reduction ceiling to suitable on the field.

A Study on the Heat Transfer Characteristics of the Radiant Chilled Ceiling Panel for Space Cooling (냉각된 복사천장패널의 열전달 특성에 관한 연구)

  • Lee, Tae-Won;Hwang, In-Ju
    • Proceedings of the KSME Conference
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    • 2001.06d
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    • pp.164-169
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    • 2001
  • There is a chilled ceiling panel which carries out the air conditioning by radiation and convection between the room and cold ceiling panel surface. In order to verify heat transfer characteristics between them in cooling system with radiant chilled ceiling panel, analytical and experimental studies were performed for various design and operating parameters such as tube space and diameter, inlet water temperature, mass flow rate, cooling load, and so on. In this study, we found that the tube space and inlet water temperature were more important elements than the tube diameter and water flow rate for the performance of radiant chilled ceiling panel. The cooling capacity of the radiant chilled ceiling panel had the maximum value of $65W/m^{2}$ because the highest cooling capacity was limited by the condensation on the panel surface. The results of comparison between numerical analysis and experiment showed a resonable agreement qualitatively, especially for low cooling capacity.

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Evaluation for The Heavy-weight Impact Sound Reduction Performance of Dry Double-Floor System (건식 이중바닥구조의 중량충격음 저감성능 평가)

  • Yeon, Junoh;Kim, Kyoungwoo;Choi, Hyunjuong;Yang, Kwanseop;Kim, Kyungho
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2012.10a
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    • pp.280-285
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    • 2012
  • The 1st assessment (performance test) was applied to assure the floor impact sound performance for developing the dry double- floor with the change of rubber hardness of the upper panel's support and the ceiling structure of the sub-floor. Depends on the change of the rubber hardness in substructure, the heavy-weight sound impact value is improved up to 3 dB, and the light-weight sound impact value is moved up to 21 dB, comparing with the bare-slab. Also, the improved value for the floor impact sound conjugating with the sub-floor's ceiling was 5dB. Based on this result, the 2nd assessment (performance test) was made the state that the rubber hardness of the sub-floor support was ranged between 50 and 70 for considering the stability of walking patients. In addition to this process, the assessment was carried out with a variety of ceiling structure applied to the dry doublefloor structure with the air flow system on the sub-floor's ceiling. The result for the 2nd assessment proved that TYPE-11 had the better sound reduction performance in the heavy-weight impact sound test than other types, and also for the light-weight impact sound TYPE-11 had the 29 dB sound reduction performance overall. Henceforth, based on the result the research for the sound reduction performance from the floor impact sound shall be ongoing process as well as the development of a double-dry floor and a sound reduction ceiling to suitable on the field.

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Analysis of the Room Acoustic Characteristics depending on the Sound Sources for a Multi-purpose Gymnasium finished with Absorbers on Walls and Ceiling (벽 및 천장이 흡음재로 마감된 다목적 체육관에서 음원종류에 따른 실내음향특성의 분석)

  • Park, Hyeon-Ku;Jeon, Ji-Hyun;Song, Hyuk;Kim, Sun-Woo
    • KIEAE Journal
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    • v.2 no.1
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    • pp.41-48
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    • 2002
  • This study aims to investigate and evaluate the room acoustic designs of a multi purpose gymnasiums which do not use adjustable treatments in order to change the acoustical characteristics. Considering the main uses of gymnasium and auditorium, experiments were carried out using both nondirectional speakers on the stage and loudspeaker installed on the ceiling. The result from the study are as follows; Measured RT under unoccupied condition was a little longer than the expected value, therefore, in the case of occupied condition RT would be close to the optimum value. However, parameters that evaluate intelligibility and speech transmission property appeared to be low and have large differences depending on the measuring points, therefore, more effective sound reflecting surfaces and sound reinforcement systems should be considered.

Occupational Exposure of Semiconductor Workers to ELF Magnetic Fields (반도체 제조 근로자의 극저주파 자기장 노출 평가)

  • Chung, Eun Kyo;Kim, Kab Bae;Chung, Kwang Jae;Lee, In Seop;You, Ki Ho;Park, Jung-Sun
    • Journal of Korean Society of Occupational and Environmental Hygiene
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    • v.22 no.1
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    • pp.42-51
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    • 2012
  • Objectives: To compare the exposure level of extremely low frequency (ELF) magnetic fields among semiconductor workers, shipyard welders and office workers. Methods: To measure the ELF magnetic field concentration, EMDEX LITE (Enertech, USA) were used and monitored for eight hours continuously. Five companies handling the electric and magnetic field (EMF) source were investigated, which the exposure groups were classified into three groups: semiconductor workers, welders, and office workers. Welder group was chosen as a high exposed group and office group as a low exposed group. Results: The arithmetic mean (${\pm}SD$) and geometric mean (GSD) of personal exposure level of semiconductor workers were 0.73 (${\pm}1.33$) ${\mu}T$, 0.43 (2.88) ${\mu}T$, respectively. The ceiling value ranged between 0.18 and 123.2 ${\mu}T$. Welders were exposed high with the arithmetic mean value of 3.46 (${\pm}\;13.46$) ${\mu}T$ and geometric mean value of 0.45 (4.70) ${\mu}T$, respectively, and ceiling value range of 75.5~129.6 ${\mu}T$. The exposure levels of office workers were low compared to other exposed groups; the arithmetic mean 0.05 (${\pm}0.13$) ${\mu}T$, geometric mean 0.03 (2.38) ${\mu}T$ and ceiling value range 0.37~3.35 ${\mu}T$. This study revealed statistically significant differences of the mean ELF magnetic field exposure doses among three groups (p < 0.01). Conclusions: The average ELF magnetic field exposure doses of semiconductor workers were much higher than those of office workers in control group, but were lower than those of welders in high exposure group.

Prediction of Reduction Rates of Daylight Illuminance for Blind Conditions in a Small Office (소규모 사무실의 블라인드 조건에 따른 주광조도 감소비율 예측)

  • Gu, Renyan
    • Land and Housing Review
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    • v.12 no.2
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    • pp.79-89
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    • 2021
  • This simulation based study analyzed the horizontal daylight distribution on the floor and ceiling of a small office space based on window orientations and interior window blind positions. South and north facing windows were each tested without window blinds and with window blinds at 45° and 180° (horizontal). The study showed that the illuminance value was highest 1m from the window. On the floor and ceiling, the difference in illuminance value was the greatest and least in December and June, respectively. The indoor illuminance value was highest when there was no window blind and under south-facing conditions. The greatest illuminance difference occurred between window blinds positioned at 45° and 180°. Under north-facing conditions, windows without blinds or with blinds at 45° had the least impact on indoor illuminance with illuminance being more evenly distributed.

Characteristic Analysis and Experimental Verification of the Axially Asymmetric Structured Outer-Rotor Type Permanent Magnet Motor

  • Seo, Myung-Ki;Lee, Tae-Yong;Park, Kyungsoo;Kim, Yong-Jae;Jung, Sang-Yong
    • Journal of Electrical Engineering and Technology
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    • v.11 no.4
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    • pp.898-904
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    • 2016
  • In this study, we have dealt with a design characteristic of outer-rotor type permanent magnet (PM) motor applied for Engine Cooling Fan (ECF). When we design a motor with structure like this type, it is required as a requisite to consider 3-Dimensional (3-D) effect by implementing a non-linear Finite Element Analysis (FEA) due to a yoke-ceiling, which is perpendicular to the axis of rotation. We have analyzed identical models under three different conditions. The analysis has been performed through a non-linear 2-Dimensional (2-D) and 3-D FEA. Finally, the results have been compared with Back Electro-Motive Force (BEMF) value of actual motor model. As a result, a yoke-ceiling function as an additional flux path and the operating point on B-H curve of rotor material is shifted to non-saturation region relatively. Accordingly, magnetic flux linkage can be increased and motor size can be decreased under same input condition to satisfy ECF specification, such as torque.

Evaluation of the clean air delivery rate performance of a ceiling air circulator with filters (필터 적용 천정형 공기순환기의 공기청정화능력 평가)

  • Joe, Yun-Haeng;Shin, Dongho;Park, Hyun-Seol;Heo, Jieun;Shim, Joonmok
    • Particle and aerosol research
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    • v.17 no.2
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    • pp.29-36
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    • 2021
  • In this study, the clean air delivery rate (CADR) of ceiling air circulator (CAA) was determined under indoor environmental simulation conditions. An air filter was used to provide air cleaning ability to the CAA. The CADR of filter adapted CAA was evaluated and compared with the value of commercial air purifier. The installation of mesh-shaped filter on the CAA showed particle reduction effect on the particles over 0.4 ㎛ in diameter, but the CADR was up to 0.25 m3/min. When the filter having 99.9% in collection efficiency was installed on the CAA, its CADR was 1.52 m3/min, while the CADR of commercial air purifier was 3.19 m3/min.

Fire Simulation for Vent Flow and Temperature in Engine Room of Small Ship: Effects of Ceiling Duct Location and Side Vent Size (소형선박 기관실의 개구부 유동 및 온도에 대한 화재시뮬레이션: 천장 통풍통 위치 및 측면 개구부 크기 영향)

  • Jeong, Lee-Gyu;Lee, Chi Young
    • Journal of the Korean Society of Marine Environment & Safety
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    • v.26 no.5
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    • pp.454-465
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    • 2020
  • Fire simulations were performed using the Fire Dynamics Simulator (FDS) software to examine the vent flow and temperature in the engine room of a small ship. A diesel fire with a heat release rate of 10 kW was targeted, and the effects of the ceiling duct location, side vent existence and nonexistence, and side vent size were investigated. The existence or nonexistence of the side vent and its size considerably affected the smoke behavior, mass flow rate through the vent, and temperature. When the side vent was not installed or was small, the smoke layer reached the floor in the engine room. In addition, as the side vent size increased, the mass flow rate through the vent increased with decreasing temperature value. However, the effects of the ceiling duct location on the smoke behavior, mass flow rate through the vent, and temperature seemed to be relatively minor compared to those of the side vent size. Therefore, to improve the fire safety of the engine room in a small ship, the side vent size is considered to be a more important design factor than the ceiling duct location.

Structural Performance of the Modular System with Fully Restrained Moment Connections using Ceiling Bracket (천장 브래킷을 이용한 완전강접합 모듈러 시스템의 구조성능)

  • Lee, Seung-Jae;Kwak, Eui-Shin;Park, Jae-Seong;Kang, Chang-Hoon;Shon, Su-Deok
    • Journal of the Architectural Institute of Korea Structure & Construction
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    • v.33 no.12
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    • pp.37-44
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    • 2017
  • Due to structural characteristics, construction costs and duration of a modular system would be saved by minimizing the schedule on the job site. As such, it is crucial to develop a connection that can guarantee stiffness while allowing for simple assembling. Particularly, the mid- to high-rise construction of the modular system necessitates the securing of the structural stability and seismic performance of multi-unit frames and connections, and thus, the stiffness of unit-assembled structures needs to be re-evaluated and designed. However, evaluating a frame consisting of slender members and reinforcing materials is a complicated process. Therefore, the present study aims to examine the structural characteristics of a modular unit connection based a method for reinforcing connection brackets and hinges while minimizing the loss of the cross section. Toward this end, the study modeled the beam-to-column connection of a modular system with the proposed connection, and produced a specimen which was used to perform a cycling loading test. The study compared the initial stiffness, the attributes of the hysteretic behavior, and the maximum flexural moment, and observed whether the model acquired the seismic performance, compared to the flexural strength of the steel moment frame connection that is required by the Korean Building Code. The test results showed that the proposed connection produced a similar initial stiffness value to that of the theoretical equation, and its maximum strength exceeded the theoretical strength. Furthermore, the model with a larger ceiling bracket showed higher seismic performance, which was further increased by the reinforcement of the plate.