• Wind and Structures
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• v.24 no.5
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• pp.501-528
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• 2017

In this work, wind tunnel tests of pressure measurements are carried out to assess the global aerodynamic interference factors, the local wind pressure interference factors, and the local lift spectra of an square high-rise building interfered by an identical cross-sections but lower height building arranged in various relative positions. The results show that, when the interfering building is located in an area of oblique upstream, the RMS of the along-wind, across-wind, and torsional aerodynamic forces on the test building increase significantly, and when it is located to a side, the mean across-wind and torsional aerodynamic forces increase; In addition, when the interfering building is located upstream or staggered upstream, the mean wind pressures on the sheltered windward side turn form positive to negative and with a maximum absolute value of up to 1.75 times, and the fluctuating wind pressures on the sheltered windward side and leading edge of the side increase significantly with decreasing spacing ratio (up to a maximum of 3.5 times). When it is located to a side, the mean and fluctuating wind pressures on the leading edge of inner side are significantly increased. The three-dimensional flow around a slightly-shorter disturbing building has a great effect on the average and fluctuating wind pressures on the windward or cross-wind faces. When the disturbing building is near to the test building, the vortex shedding peak in the lift spectra decreases and there are no obvious signs of periodicity, however, the energies of the high frequency components undergo an obvious increase.

• The korean journal of orthodontics
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• v.23 no.1 s.40
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• pp.89-100
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• 1993

The purpose of this study was to evaluate the effect of orthodontic force on periodontal cellular activity by immunoperoxidase stain of epidermal growth factor, one of the tissue hormone. And supplementarily, to investigate of the changes of periodontal structures, periodontium was stained by H-E, Masson's Trichrome, P. A. S. stain after orthodontic force application. The experimental animals were four young adult dogs of average 8 month old. The fixed orthodontic appliance was cemented on mandibular right 4th premolar and 1st molar of each animal as experimental site. Mandibular left 4th premolar area of the same animal was used as control. The appliance consist of two silver crown soldered with 0.030' tube, $0.018\times0.022'$ S.S. sectional arch wire, and 0.009' open coil spring for manifestating of orthodontic force for bodily tooth movement of mandibular 4th premolar toward mesial direction. Experimental group was sacrificed at 1, 2, 3, 5 weeks from beginning of the experiment, and was investigated immunohistochemically and bistochemically by several staining methods. Findings were as follows: 1. The degree of EGF staining in control group was highest in epithelium of periodontium, and osteoclasts, osteoblasts and fibroblasts around the capillary were stained at higher level in periodontium. Generally, control group shows positive distribution of EGF all around the periodontal area. 2. The degree of EGF staining in control and 5 week group were similar, and did not show the significant different level between tension and pressure side. 3. All of 1, 2, 3 week group showed the same staining degree and distribution of EGF, and the tension side was more positive reaction of EGF stain than the pressure side. 4. The features of collagen fiber and periodontal fiber arrangement observed by H-E, Masson's Trichrome and P. A. S. stain revealed that oblique periodontal fibers were strectched in tension side, compressed in pressure side of all experimental group. Some fiber group in pressure side of 5 week group recovered the regular arrangement along the capillaries.

• Fire Science and Engineering
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• v.24 no.3
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• pp.93-98
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• 2010

Even though the sprinkler system is a essential fire suppression system, the design engineers do not fully understand the concept of design area which sprinklers operate. They frequently made a mistake to form design area and calculate it. The shape of design area is a square or a rectangle which branch side line is a little longer than the cross main side. NFPA demands to lengthen the branch side to 1.2 times than the cross main side and FM demands 1.4 times. The longer the branch side at the same design area is, the bigger the water quantity and pressure is. At the results of hydraulic calculation of design areas, when the branch side is longer 1.2 times, the water quantity became 4.6% bigger than exact square and the pressure came to 4.67% bigger. When it is longer 1.4 times, the water quantity and the pressure are bigger 7.52%, 14.51%. Therefore, the sprinkler design engineers should follow the general rule of design area, exact square or rectangle which length along the branch line is a little longer than length along the cross main, to design more stable system.

• Journal of The Korean Society of Integrative Medicine
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• v.1 no.2
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• pp.37-46
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• 2013

Purpose : The purpose of the research was to analyze foot pressure, foot temperature, and correlation between foot pressure and foot temperature to grasp impact on foot pressure and body temperature distribution chart depending on functional difference of leg length. Method : After measuring leg length, put 15 students whose functional difference of leg length was over 10mm to difference group and 15 students whose functional difference of leg length was under 5mm to normal group and categorize soles of foot into 6 sections of hallux head, 1st metatarsal head, 2-4 metatarsal head, 5 metatarsal head, lateral heel, and then measure by foot pressure analyzer to analyze characteristic of pressure distribution and classify into front of the lower leg, back of the lower leg, soles of foot and measure by body temperature analyzer to analyze by checking body temperature. Result : Weight difference depending on foot pressure and body temperature was bigger when functional difference of leg length was bigger, and it could be confirmed that foot pressure and body temperature of short leg side were higher than those of short leg side. Thus, if difference exists in leg length, weight load on short leg side increases which results in higher foot pressure and body temperature, therefore enabling an assumption that mechanical problem will occur in short leg. Conclusion : When functional leg length inequality, weight bearing and pressure was getting high as a result, temperature was getting high in short leg.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.15 no.12
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• pp.1007-1017
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• 2003

An experimental study on the air-side pressure drop and heat transfer coefficient of slit fin-tube heat exchanger has been carried out. The data reduction methodology for air-side heat transfer coefficients in the literature is not based on a consistent approach. This paper focuses on new method of data reduction to obtain the air-side performance of fin-tube heat exchanger using R22 and recommends standard procedures for dry and wet surface heat transfer estimation in fin-tube heat exchanger having refrigerant on the tube-side. Results are presented as plots of friction f-factor and Colburn j -factor against Reynolds number based on the fin collar outside diameter and compared with previous studies. The data covers a range of refrigerant mass fluxes of 150∼250 kg/$m^2$s with air flows at velocity ranges from 0.3 m/s to 0.8 m/s.

• Proceedings of the Korean Nuclear Society Conference
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• 1996.05b
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• pp.405-410
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• 1996

New methodology for mass and energy release assessment in LBLOCA post blowdown is needed and, first of all, the phenomenologically improved and quantitative assessments through experiment are essential. For tile experiment of a hot leg break LBLOCA in post blowdown, the test facility was set and its feature is that tile broken hot leg has two broken sections in the tore side and in the SG side respectively and a separation valve between the two in order to measure the release rate dividedly. Specially it was focused on whether the mass release through the SG side broken section happened or not. The mass release through the core side broken section is dependent on tile safety injection flow and that through the SG side broken section varies depending on several factors. The principal factor is the primary system pressure and the subfactors such as SI flow rate, SI temperature and initial primary pressure, may contribute, too.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.15 no.3
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• pp.220-229
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• 2003

An experimental study on the air-side pressure drop and heat transfer coefficient of slit fin-tube heat exchanger has been carried out. The data reduction methodology for air-side heat transfer coefficients in the literature is not based on a consistent approach. This paper focuses on new method of data reduction to obtain the air-side performance of fin-tube heat exchanger using R22 and recommends standard procedures for dry surface heat transfer estimation in fin-tube heat exchanger having refrigerant on the tube-side. Results are presented as plots of friction f-factor and Colburn j -factor against Reynolds number based on the fin collar outside diameter and compared with previous studies. The data covers a range of refrigerant mass fluxes of 150~250 kg/$m^2$s with air flows at velocity ranges from 0.6 m/s to 1.6 m/s.

• Wind and Structures
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• v.35 no.3
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• pp.193-211
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• 2022

The present study focuses on aerodynamic parameters behaviors and control on the single and double side setback building models at the buildings mid-height. The study is conducted by computational fluid dynamics (CFD) simulation. This study estimates the face wise pressure coefficient on single side setback buildings with a setback range of 20%-50% and double side setback buildings with setbacks ranging from 10%-25%. The polynomial fitted graphs from CFD data predict the Cp on different setback model faces within permissible limit ±13% error. The efficient model obtained according to the minimum drag, lift, and moment consideration for along and across wind conditions. The study guides the building tributary area doesn't control the drag, lift, and moment on setback type buildings. The setback distance takes a crucial role in that. The 20% double side setback model is highly efficient to regulate the moment for both along and across wind conditions. It reduces 17.5% compared to the 20% single side setback and 14% moment compared to the 10% double side setback models. The double side setback building is more efficient to control 4.2% moment than the single side setback building

• International Journal of High-Rise Buildings
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• v.11 no.4
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• pp.241-263
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• 2022

The conventional wind and twisted-wind effect on aerodynamic properties of neighboring buildings arranged in side-by-side and tandem systems at 2B and 5B spacings are systematically investigated by large eddy simulation. Different physical interactions between different wind profiles and neighboring buildings will be deeply understood. The neighboring-building system under two different types of wind profiles, i.e., conventional wind profile (CWP), twisted wind profiles (TWP) with the maximum twisted angle of 30°, is used to evaluate the variation of physical mechanism between wind and buildings. Aerodynamic characteristics including mean and RMS pressure coefficient, and velocity field were systematically analyzed and compared between different scenario. It was found that the distribution of mean pressure, root-mean-square x velocity and the streamline of wind flow for TWP greatly deviated from CWP, and the effect of TWP on the downstream building, was drastically different from that of CWP, such as the size of vortexes after the lower stream building being bigger when exposed to TWP, and the mean pressure distribution on the building surfaces are also different. Moreover, evidence of buildings arranged in side-by-side and tandem configurations having interchangeable properties under TWP was also discovered, that two buildings being arranged side-by-side exposed to TWP could be identified as being arranged in tandem with a different wind twist angle, or vice versa.

• 한국전산유체공학회:학술대회논문집
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• 2007.04a
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• pp.64-67
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• 2007

In the present study, the wind pressure transients on platform screen door in side platforms caused by passing trains have been investigated numerically. The transient compressible 3-D full Navier-Stokes solution is obtained with actual operational condition of subway train and the moving mesh technique is adopted considering the train movement. To achieve more accurate analysis, the entrance and exit tunnel of platform are included in a computational domain and detailed shape of train is also modeled Numerical analyses were conducted on five operational condition which are different velocity variation of subway train, existence of stationary train and passing each other trains. The results show that pressure load on platform screen door is maximized when the two trains are passing each other. It is also seen from the computational results that the maximum pressure variation was found to be satisfactory to various foreign standards.