• Journal of Korean Society for Atmospheric Environment
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• v.9 no.3
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• pp.191-199
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• 1993

This paper describes the results of a systematic study to determine the characteristics of particle generated from various types of asbestos containing material(ACM) and manmade fiber material(MMFM) during operations of cutting and grinding in laboratory and workplace. Tests were conducted with a specially designed glove box which allowed complete sampling of the generated asbestos fibers. Specificially, air measurements were made during ACM and MMFM installation in building. All personal air samples collected were identified by polarized light microscopy(PLM), X-ray diffraction(XRD) and scanning electron microscope with energy dispersive X-ray analysis(SEM/EDXA). Also, the samples were counted by phase contrast microscope(PCM) in order to compare the results with the permissible exposure standard for workplace. Results indicate that the characterisitcs of fibers found in the roofing sheet, the ceiling and the wall insulation boards were identical to those of asbestos, while the characteristics of fibers found in the ceiling insulation board, the floor tile and the sprayed on insulation products in parking area were identical to those of asbestos, while the characteristics of fibers found in the ceiling insulation board, the floor tile and the sprayed on insulation products in parking area were identical to those of rock wool. The concentrations of airborne fibers from various building materials cut by a grinder for 5 minutes were in the ranges of 0.09 $\sim$ 1.71 fibers/cc(f/cc). The highest concentration(1.71f/cc) was found during grinding the wall insulation board which also contains rock wool. The airborne fiber concentrations generated by installing at workplace were ranged from 0.0009 to 0.029 f/cc. All asbestos fibers from the ceiling insulation board at workplace were less than 20$\mu$m in length and more than 20% of them had the average aspect ratio greater than 20. Therefore, for the purpose of decreasing asbestos and man-made fiber concentrations at the workplace, the ceiling and wall board should use strong binding material to increase the binding force with fiber. Also, the permissible exposure standard for workplace(2.0f/cc) in Korea should be constituted below the maximum avaiable concentration measured at glove box.

• Coupled systems mechanics
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• v.2 no.4
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• pp.329-348
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• 2013

This study aims at observing the coupling behaviours between suspended ceilings and partition walls in terms of their global seismic performance using full-scale shake table tests. The suspended ceilings with planar dimensions of $6.0m{\times}3.6m$ were tested with two types of panels: acoustic lay-in and metal clip-on panels. They were further categorized as seismic-braced, seismic-unbraced, and non-seismic installations. Also, two configurations of 2.7 m high partition wall specimens, with C-shape and I-shape in the plane layouts, were tested. In total, seven ceiling-partition-coupling (CPC) specimens were tested utilizing a unidirectional seismic simulator. The test results indicate that the damage patterns of the tested CPC systems included failure of the ceiling grids, shearing-off of the wall top railing, and, most destructively, numerous partial detachments and falling of the ceiling panels. The loss of panels was mostly concentrated near the center of the tested partition wall. The testing results also confirmed that the failure mode of the non-seismic CPC systems was brittle: The whole system would collapse suddenly all at once when the magnitude of the inputs hit the capacity threshold, rather than displaying progressive damage. Overall, the seismic capacity of the unbraced and braced CPC systems could be up to 1.23 g and 2.67 g, respectively; these accelerations were both achieved at the base of the partition wall. Nonetheless, for practical applications, it is noteworthy that the three-dimensional nature of seismic excitations and the size effect of the ceiling area are parameters that exacerbate the CPC's seismic response so that their actual capacity may be dramatically decreased, leading to important losses even in moderate seismic events.

• The Journal of the Acoustical Society of Korea
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• v.24 no.1
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• pp.21-28
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• 2005

In this Paper, the effect of stage ceiling height on the acoustic characteristics of rectangular concert halls are investigated. To find out the acoustic properties of audience area, A simple Boston Symphony Hall(BSH) model which is typically rectangular shaped was applied for computer simulation. A newly built rectangular concert hall with 400 seats was also chosen for a scale model $(1.2m{\times}0.68m{\times}0.31m)$ study and its computer simulation varing the stage ceiling height and the volume. The results show that RT increased as the stage ceiling was lowered and the difference rate of RT by its variance is from -0.09 to -0.06[sec/m].

• Fire Science and Engineering
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• v.32 no.5
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• pp.40-45
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• 2018

This paper is an analysis of the influence of ceiling air conditioner airflow on fire detector response. In order to analyze the response characteristics of fire detector while forming air flow of a ceiling-type air conditioner, fire tests were carried out in accordance with ISO standard. This experiment was carried out in a fire test site of 10 m (width) ${\times}$ 7 m (length) ${\times}$ 4 m (height). As a result of the experiment, the response of fire detector shows a normal pattern that is delayed as the distance from the fire source is increased in the absence of the air conditioner, but it is confirmed that the pattern is not maintained in the strong air flow. When the air flow of air conditioner was strong, the response time was increased by 121% in the smoke detector and by 39% in the heat detector. In the case of ceiling type air conditioners, it is considered that the number of fire detectors should be increased, or a detector with high sensitivity should be installed for early detection of fire.

• Journal of Digital Convergence
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• v.14 no.11
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• pp.325-331
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• 2016

The purpose of this study is to analyze the effect of the glass ceiling induction factors on the improvement of the job Commitment on the glass ceiling perception and to analyze the effect of the organizational Commitment on the influence of the local medical institute and private medical institute employees. As a research method, structural equation model analysis was carried out to investigate the influence relationship of each factor. In particular, multiple group analysis was performed to analyze the difference of influence relations between public and private medical personnel, respectively. Result: First, empirical studies on the effect of the glass ceiling inducing factors on job Commitment showed that job Commitment was influenced by stereotype and organizational culture, and the magnitude of the influence was different. Second, the employees of the room medical center were influenced by perceived promotion, job placement, education and training, reward, and job satisfaction. Third, in the hypothesis that job Commitment will be affected by the perception of glass ceiling, only the workers of the private medical center showed significant results. Based on the results of this study, it will be necessary to plan policies to improve the perception of the glass ceiling phenomenon and improve its status in order to improve the personnel and system with which women workers in the medical field can enter more senior management positions.

• The Journal of Korea Robotics Society
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• v.6 no.3
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• pp.197-209
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• 2011

This paper presents a localization system using ceiling images in a large indoor environment. For a system with low cost and complexity, we propose a single camera based system that utilizes ceiling images acquired from a camera installed to point upwards. For reliable operation, we propose a method using hybrid features which include natural landmarks in a natural scene and artificial landmarks observable in an infrared ray domain. Compared with previous works utilizing only infrared based features, our method reduces the required number of artificial features as we exploit both natural and artificial features. In addition, compared with previous works using only natural scene, our method has an advantage in the convergence speed and robustness as an observation of an artificial feature provides a crucial clue for robot pose estimation. In an experiment with challenging situations in a real environment, our method was performed impressively in terms of the robustness and accuracy. To our knowledge, our method is the first ceiling vision based localization method using features from both visible and infrared rays domains. Our system can be easily utilized with a variety of service robot applications in a large indoor environment.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2015.11a
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• pp.187-188
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• 2015

The construction finishing work is emphasized according to high dependence on labor and long term that occupy approximately 40% in construction period, so that it is required for the alternatives such as automation technology. However, it is insufficient to develop the automation technology of construction finishing work compared to other works, for instance, frame work. Also it is not enough about this preliminary research which survey the improvement needs to select the development object. Therefore, this study aimed at derivation of detail works required improvement in ceiling finishing work by the questionnaire survey. These results may provide the basic information to develop the automation technology of construction finishing work.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2002.11b
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• pp.956-960
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• 2002

Offices and other multipurpose buildings commonly have suspended ceilings installed over room dividing wall. But Korean Standards don't include any code on test methods and test facility of the suspended ceiling system. Therefore, test methods and test facility from ISO and ASTM have been used for evaluating sound performance in domestic so fu. In this study, Korean Standards draft on test methods and test facility of suspended ceiling system and materials is proposed on the basis of ISO and ASTM.

• KIEAE Journal
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• v.9 no.2
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• pp.53-58
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• 2009

There are increasing developments and uses of functional building materials are recently developed and introduced to the test method for the materials. Especially, moisture problem has a major role are also being established in indoor air quality problems. The purpose of this study is to evaluate the water vapour adsorption/desorption property of a ceiling material. The variation of the temperature and moisture were measured with the application materials by mock up test based on JIS 1470-1. The result shows that water vapour adsorption/desorption property of ceiling material is appeared in changes of moisture adsorption and desorption in comparison with that of a general ceiling material. Therefore, in case of decreasing and increasing in humidity, these materials can be used as an finishing material to sustain comfort condition.

• Proceedings of the KIEE Conference
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• 2001.11c
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• pp.91-94
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• 2001

In this paper, we proposed localization method of mobile robot using color landmark mounted on ceiling. This work is composed 2 parts : landmark recognition part which finds the position of multiple landmarks in image and identifies them and absolute position estimation part which estimates the location and orientation of mobile robot in indoor environment. In landmark recognition part, mobile robot detects artificial color landmarks using simple histogram intersection method in rg color space which is insensitive to the change of illumination. Then absolute position estimation part calculates relative position of the mobile robot to the detected landmarks. For the verification of proposed algorithm, ceiling-orientated camera was installed on a mobile robot and performance of localization was examined by designed artificial color landmarks. As the result of test, mobile robot could achieve the reliable landmark detection and accurately estimate the position of mobile robot in indoor environment.