• Fire Science and Engineering
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• v.33 no.3
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• pp.74-83
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• 2019

In the U.S., the pressurization of elevator shaft was developed in 1972 to allow vulnerable people, such as the elderly and weak who could not use escape stairs in case of fire, to evacuate. It is an advantage in terms of space saving by not using vertical ducts. This study drew the problem of the pressurization of elevator shaft based on the existing domestic patents and proposed improvements. The smoke control volume calculation method is proposed by using vertical modeling. Leakage gaps in elevator doors need to be reviewed through experimental data or actual data. The evacuation floor was divided, the openings in the elevator machine room were automatically closed to the fire signal and the relief damper was installed to improve the performance. The improved method functions as the smoke control damper supplying the air flow rather than maintaining the differential pressure. To increase reliability of the research results, the procedure was performed to verify by using Contam.

• Tunnel and Underground Space
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• v.27 no.2
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• pp.100-108
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• 2017

As a measure of the combined effect of fracture geometry, the fabric tensor parameters could quantify the status of the connected fluid flow paths in discrete fracture network (DFN). The correlation analysis between fabric tensor parameters and hydraulic properties of the 2-D DFN was performed in this study. It is found that there exists a strong nonlinear relationship between the directional conductivity and the fabric tensor component estimated in the direction normal to the direction of hydraulic conductivity. The circular radial plots without significant variation of the first invariant ($F_0$) of fabric tensor for different sized 2-D DFN block are a necessary condition for treating representative element volume (REV) of a fractured rock mass. The relative error (ER) between the numerically calculated directional hydraulic conductivity and the theoretical directional hydraulic conductivity decreases with the increase in $F_0$. A strong functional relation seems to exist between the $F_0$ and the average block hydraulic conductivity.

• Journal of the korean society of oceanography
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• v.37 no.1
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• pp.1-9
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• 2002

Cable voltage was measured simultaneously at Hamada, Japan and Pusan, Korea, using an inservice telephone cable from March to December 1990. The spectral and harmonic analyses of these data sets show that tidal signals are dominant, and that tidal constituents $M_2$ and $O_1$, which are not affected by solar geomagnetic variations, have almost the same amplitude and are of opposite phase to each other. comparing the voltage difference in 1990 with that measured using the now abandoned cable in 1998, there are dominant tidal signals at the same periods in both data sets. They have approximately the same amplitude and phase for $M_2andO_1$. The relationship between the observed voltage and the volume transport through the Korea Strait can be considered robust and stable over time. The conversion factor from voltage to transport is estimated to be $11.9{\times}10^6m^3S^{-1}volt^{-1}$ by comparing the amplitude of model-derived $M_2$ tidal transport with that of the voltage difference in 1998. This value changes to $8.6{\times}10^6m^3S^{-1}volt^{-1}$ when taking into consideration the horizontal electric current effect. This effect depends on the downstream length scale of the flow. To obtain a more reliable and stable conversion factor from voltage to transport, the voltage should be compared with observed sub-tidal transports, which may have long downstream length scales.

• The Journal of the Korea Contents Association
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• v.11 no.2
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• pp.457-465
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• 2011

This research, which was started with a need for constant monitoring to find out urban societies and spacial effects by urban railway after the opening, was intended to empirically explore urban and social changes by the opening of Daejeon City metro line 1st which would greatly affect the spacial structure of the city. For this goal, we expected the effect of urban subway on the city with academic consideration and precedent study. Monitoring results of the subway station areas of Daejeon City metro line 1st showed the opening of urban railway had an influence on the flow of urban plan and urban space structure through population, land use, total-developing areas, and land price change. In other words, as urban railway opens the number of population and population activities centered on the subway station areas, and these movements led to the expansion of the commercial areas. Finally, they caused the average land prices to rise. Likewise, urban monitering is significantly useful comprehending the generally time-periodic changes of cities and even conceiving the present cities.

• Tunnel and Underground Space
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• v.23 no.6
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• pp.470-479
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• 2013

Hydraulic fracturing is used as a method for promoting the fluid flow in the rock and, in the energy field such as geothermal development and the development of sales gas, many studies has been actively conducted. In many cases, hydraulic fracturing is not performed in isotropic rock and especially in the case of sedimentary rocks, hydraulic fracturing is conducted in the transverse isotropic rock. The direction of the crack growth on hydraulic fracturing does not necessarily coincides with the direction of maximum principal stress in the transverse isotropic rock. Therefore, in this study, bonded particle model with hydro-mechanical coupling analysis was adopted for analyzing the characteristics of hydraulic fracturing in transverse isotropic rock. In addition, experiments of hydraulic fracturing were conducted in laboratory-scale to verify the validity of numerical analysis. In this study, the crack growth and crack patterns showed significant differences depending on the viscosity of injection fluid, the angle of bedding plane and the influence of anisotropy. In the case of transverse isotropic model, the shear crack growth due to hydraulic fracturing appeared prominently.

• Tunnel and Underground Space
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• v.23 no.6
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• pp.572-580
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• 2013

In this case study, I examined the microseismic safety management system of Deep Heat Mining Basel (DHMB) as EGS Geothermal Project which was conducted in Basel, Switzerland. EGS Geothermal Power projects which require induced seismic event by stimulation for creation of EGS geothermal reservoir have to be controlled pressure and flow rate of stimulation by establishment of microseismic safety management system. Traffic light system and Communication response procedure of DHMB project to respond step by step corresponding microseismic event intensity through continuous monitoring during stimulation period have been managed and established in advance of stimulation. However, the project was discontinued because of an earthquake to occur larger than expected one due to post-injection seismicity occurring in the geothermal reservoir after completion of injection for stimulation. The result of post analysis, Real-time traffic light system was verified to need a establishment of new microseismic safe management system to be considered post-injection seismicity phenomenon.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.40 no.7
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• pp.1339-1346
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• 2015

The traffic identification is a preliminary and essential step for stable network service provision and efficient network resource management. While a number of identification methods have been introduced in literature, the payload signature-based identification method shows the highest performance in terms of accuracy, completeness, and practicality. However, the payload signature-based method's processing speed is much slower than other identification method such as header-based and statistical methods. In this paper, we first classifies signatures by matching type based on range, order, and direction of packet in a flow which was automatically extracted. By using this classification, we suggest a novel method to improve processing speed of payload signature-based identification by reducing searching space.

• Nuclear Engineering and Technology
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• v.23 no.2
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• pp.183-199
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• 1991

Transient response of temperature distributions in a Pressurized Water Reactor (PWR) pressurizer vessel wall for the Inadvertent Auxiliary Spray transient has been analyzed with conservatism accounted for the resulting thermal stresses in the regions of the vessel wall which are wetted by the spray water droplets. In order to determine the forced convective heat transfer coefficient at the inner boundary surface of vessel wall where the droplets impinge on and flow down, the transient temperatures of spray droplets when they reach the inner surface of the vessel wall after travelling from the spray nozzle through the pressurizer interior space occupied with the saturated steam-noncondensable hydrogen gas mixture have been predicted. The transient temperature distributions in the vessel wall have been obtained by using the finite element method, and the typical results have been provided. It has been shown that the results of thermal analysis are consistent with representation of the input transient and have plausible physical meaning.

• Journal of the Korean Society of Propulsion Engineers
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• v.14 no.2
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• pp.10-18
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• 2010

Scramjet engine is one of the core parts of hypersonic vehicle of next generation and being investigated by many countries. Korea Aerospace Research Institute performed a ground test of the model scramjet engine S1 in 2007. And, S2 model which is improved from S1 model in engine startability and thrust was tested with HIEST (High Enthalpy Shock Tunnel) at Kakuda Space Center of JAXA. Design condition of S2 model was Mach 6.7, however, it was tested at Mach 7.7 as an off-design condition test. As a test result, flow separation was found at the inside of the intake, but the engine showed stable combustion pressure distribution. Furthermore, compared to other test models, S2 model showed a good performance value in thrust and specific impulse.

• Journal of Environmental Science International
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• v.12 no.9
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• pp.997-1004
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• 2003

The objective of this research was to test whether, under controlled laboratory conditions, hybrid SNCR/SCR process improves N $O_{x}$ removal efficiency in comparison with the SNCR only. The hybrid process is a combination of a redesigned existing SNCR with a new downstream SCR. N $O_{x}$ reduction experiments using a hybrid SNCR/SCR process have been conducted in simple NO/N $H_3$/ $O_2$ gas mixtures. Total gas flow rate was kept constant 4 liter/min throughout the SNCR and SCR reactors, where initial N $O_{x}$ concentration was 500 ppm in the presence of 5% or 15% $O_2$. Commercial catalysts, $V_2$ $O_{5}$ -W $O_3$-S $O_4$/Ti $O_2$, were used for SCR N $O_{x}$ reduction. The residence time and space velocity were around 1.67 seconds and 2,400 $h^{-1}$ or 6000 $h^{-1}$ in SNCR and SCR reactors, respectively. N $O_{x}$ reduction of the hybrid system was always higher than could be achieved by SNCR alone at a given value of N $H_{3SLIP}$. Optimization of the hybrid system performance requires maximizing N $O_{x}$ removal in the SNCR process. An analysis based on the hybrid system performance in this lab-scale work indicates that a equipment with N $O_{xi}$ =500 ppm will achieve a total N $O_{x}$ removal of about 90 percent with N $H_{3SLIP}$ $\leq$ 5 ppm only if the SNCR N $O_{x}$ reduction is at least 60 percent. A hybrid SNCR/SCR process has shown about 26∼37% more N $O_{x}$ reduction than a SNCR unit process in which a lower temperature of 85$0^{\circ}C$ turned out to be more effective.be more effective.