• Journal of Korean Association for Spatial Structures
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• v.4 no.4 s.14
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• pp.65-76
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• 2004

Walking loads are usually considered as nodal loads in the finite element vibration analysis of structures subjected to walking loads. Since most of the walking loads act on elements not nodes, the walking loads applied on the elements should be converted to the equivalent nodal walking loads. This paper begins with measuring walking loads by using a force plate equipped with load cells and investigates the characteristics of the walking loads with various walking rates. It is found that the walking loads are more affected by walking rates than other parameters such as pedestrian weight, type of footwear, surface condition of floor etc. The measured walking loads are used as input loads for a finite element model of walking induced vibration. Finally, this paper proposes the equivalent nodal walking loads that are converted from the walking loads acting on elements based on finite element shape functions. And the proposed equivalent walking loads are proved to be applicable for efficient analysis of floor vibration induced by walking loads.

• Steel and Composite Structures
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• v.30 no.6
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• pp.577-589
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• 2019

In this study, on-site testing was carried out to investigate the vibration performance of a composite steel-bar truss slab with steel girder system. Ambient vibration was performed to capture the primary vibration parameters (natural frequencies, damping ratios, and mode shapes). The composite floor possesses low frequency (< 10 Hz) and damping (< 2%). Based on experimental, theoretical, and numerical analyses on natural frequencies and mode shapes, the boundary condition of SCSC (i.e., two opposite edges simply-supported and the other two edges clamped) is deemed more reasonable for the composite floor. Walking excitations by one person (single excitation), two persons (dual excitation), and three persons (triple excitation) were considered to evaluate the vibration serviceability of the composite floor. The measured acceleration results show a satisfactory vibration perceptibility. For design convenience and safety, a crest factor ${\beta}_{rp}$ describing the ratio of peak acceleration to root-mean-square acceleration induced from the walking excitations is proposed. The comparisons of the modal parameters determined by ambient vibration and walking tests reveal the interaction effect between the human excitation and the composite floor.

• Journal of the Korean Society of Clothing and Textiles
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• v.22 no.1
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• pp.149-158
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• 1998

The purpose of this study was to investigate the effect of age on the human thermoregulatory responses and to obtain the basic information of the Korean thermophysiological characteristics under the traditional Korean floor heating system-Ondol. The participants consisted of 10 elderly women, 4 elderly men(over 65 years), 10 young women and 5 young men(in twenties). They were exposed to temperature-controlled Ondol room(20$\pm$1$^{\circ}C$, 50$\pm$5%R.H., floor surface temperature: 30$\pm$1$^{\circ}C$) for 60 minutes and wore the same experimental clothing. The postures were performed sitting and supine on the floor. In each pose, rectal temperature, skin.temperature of 10 areas, mean skin temperature, clothing microclimate, body fat were measured. The results were as follows; 1. The rectal temperature gradually decreased and mean skin temperature gradually increased in young and old groups in both supine and sitting pose on heated Ondol floor for 60 minutes. 2. Rectal temperature was different in each pose. The rectal temperature decreased 0.1$^{\circ}C$ in both groups under the condition of sitting and decreased 0.2'c in elderly group under the condition of supine. In supine pose, elderly group was more declined than young group. Mean skin temperature increased 0.5$^{\circ}C$ in both poses, both groups.

• Korean Institute of Interior Design Journal
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• v.17 no.1
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• pp.155-161
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• 2008

In Seowon architecture, there are four kinds of space conditions according to the site plan and the figure of education area. The education area has three main buildings such as Kangdang, Dongjae, Seojae. In case Kangdan locates in front of Dongjae and Seojae(so called Junkangdang-Hoojaesa), but in another case Dongjae and Seojae locates in front of Kangdang(so called Junjaesa-Hookangdang). This four space conditions affect to decide the floor plan and the window & door system of Kangdang. In Junjaesa-Hookangdang type, the front and rear wall has more open system than in Junkangdang-Hoojaesa type. In Junjaesa-Hookangdang type the direction of Kangdang is absolutely open to front education area, but in Junkangdang-Hoojaesa type the direction of Kangdang is absolutely open to rear education area. These floor plan aims at making up education area more closely. In window & door system the rear parts of Junjaesa-Hookangdang type have generally opaque system such as Golpanmoon or Panjangmoon, but Junkangdang-Hoojaesa type breaks this rule in order to emphasize front facade of building.

• Journal of the Korean Society of Industry Convergence
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• v.3 no.4
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• pp.307-317
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• 2000

The purpose of this study is to form a calculation formula of the mean skin temperature on the human body in a heated room by the use of floor heating system. Korean traditional floor heating system is a long way from being defunct. The floor heating systems based on hot water have been coming into wide use mainly in the apartment house. However, it is considered that the design process and evaluation method for the floor heating systems in the standpoint of human being are not established so far. In the floor heating systems, air temperature as well as floor temperature should be considered as physical factors which affect the sensation of human body. Furthermore, extremely few studies have been performed on the sitting with legs crossed posture sedentary which is the typical dwelling life style of residents from the ancient times in Korea, while a large number of studies on the influence of the floor heating systems on the human body in standing and sitting on a chair sedentary have been carried out. Especially, it is essential to elucidate how mean skin temperature on the human body is affected by thermal conduction in the contact area between the sitting with legs crossed posture sedentary human body and floor including thermal radiation due to the combination of air temperature and floor temperature, but the studies dealt with such issues have hardly been performed. Based on the above statements, the influence of the environment condition due to the combination of air temperature and floor temperature is discussed in the present investigation through theoretical of mean skin temperature on the human body in the floor heating systems.

• Journal of the Korean Society of Industry Convergence
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• v.5 no.1
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• pp.81-89
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• 2002

The objective of this paper is to clarify the combined effect of heat conduction, air temperature and thermal radiation on the person seated on the floor under operation of floor heating system. Experiments were conducted for summer seasons under 8 kinds of condition: combinations of air temperature $20^{\circ}C$, $22.5^{\circ}C$ and floor temperature $20^{\circ}C$, $22.5^{\circ}C$, $30^{\circ}C$, $35^{\circ}C$ and $40^{\circ}C$ under still air. Japanese and Koreans were adopted as subjects. To evaluate the effect of conduction operative temperature modified by heat conduction was derived from the human heat balance equation. New weighting coefficients were estimated from the modified operative temperature and modified mean skin temperature. As for thermal sensation the modified operative temperature more significantly correlated to that sensation each heat transfer processes. As the floor temperature is higher, the human conduction heat gain from floor increase and the dry heat from the human body decrease.

• Journal of the Korean Society of Safety
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• v.28 no.2
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• pp.14-20
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• 2013

All most of floors can become less slip resistant with wear. The deterioration of slip resistance can often occur rapidly. So relatively new products can become hazardous within a short period of time. The main objective of this study was the comparison of slip resistance variations caused by traffic wear and accelerative wear. The second objective was to ascertain the effect of wear, and to find out the causes of slip resistance change. Although statistical differences were observed between results of traffic wear and accelerative wear, the trend of the variations of slip resistance caused by traffic wear and accelerative wear was very similar. The measured slip resistance of tested floor changed up to 29%(and 26.5%) after 100,000 steps(and 750 cycles). As the traffic wear and accelerative wear were progressed, the surface roughness of the tested floor became smoother, and so the floor became more slippery under the wet condition. The abraded(worn out) floor surface tended to become hydrophilic surface, while the new floor surface tended to show hydrophobic nature. This phenomenon would change the wettability of floor surface, and the wettability would affect the variation of slip resistance.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 1998.04a
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• pp.371-376
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• 1998

As the requirement of high-rise buildings in big cities increases, steel structural system becomes more popular in spite of the relatively higher material cost compared to that of the concrete structural system. Most of the steel structure adopts metal deck floor system because of the easiness in construction. However, the metal deck floor system has a weakness on vibration which became very important factor in office buildings, hotels and residential buildings as the more sensitive machines being used. Therefore, most, of the building codes in many countries restrict the natural frequency of the each floor should be higher than or equal to 15 Hz. Floor vibration of the KEM deck composite floor system which has been , developed recently from the engineers and scientists in Korea was measured. Also, the simplified analytical derivation of natural frequency for each floor was studied according to the measured natural frequency for each different boundary condition of the floor. As the length of the slab gets bigger, the natural frequency of the slab becomes lower even though the structural designer still considers it as a one-way slab.

• Proceedings of the SAREK Conference
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• 2009.06a
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• pp.154-158
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• 2009

The vortex ventilation system (VV) which uses a rotating finned swirler installed coaxially with the exhaust duct is a very effective local ventilator. VV can enhance the capture depth by a factor of 3-5 compared to the conventional exhaust hood, in the absence of any solid walls nearby. In real situations there may exist ceiling, side wall and floor, all of which can affect the flow field and suction performance by way of the no-slip condition on the walls. 3D CFD simulation was performed in order to see the effect of the floor on the capture performance of the VV. The presence of floor reduced suction flow velocity, and increased the critical rotational speed which is the rotational speed required for stable vortex formation. Flow velocity profile along the axis could be well approximated by a universal functional form when the distance from the exhaust inlet is non-dimensionalized by the distance to the floor. Capture depth, define by the distance from the exhaust inlet to a point of velocity decreased to 10% of that at the inlet, is reduced by about 10% when the floor distance is 6 times the exhaust hood diameter.

• Journal of Aerospace System Engineering
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• v.11 no.6
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• pp.64-67
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• 2017

This work dealt with structural safety analysis about sandwich composite structure of automotive floor board. In this work, structural design and analysis of sandwich composite structure for automobile floor board were performed. Firstly, structural design requirement of automobile floor board was investigated. After structural design, the structural analysis of the automobile floor board were performed by the finite element analysis method. It was performed that the stress and displacement analysis at the applied load condition. After structural test of target structure, structural test results were compared with analysis results. Through the structural analysis, it was confirmed that the designed floor board structure is safety.