• Journal of the Korea institute for structural maintenance and inspection
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• v.14 no.3
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• pp.118-122
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• 2010

The study presents a standard time-temperature curve to evaluate the fire performance of subway tunnel structures. The central subway section is 135km long in Korea, the fourth longest in the world. The number of subway tunnels has been increasing rapidly and fire risk is proportional to the tunnel length. However, an adequate time-temperature curve for subway tunnel fires does not exist. Therefore, we studied a proposed foreign fire design model for which the heat rate is based on the traffic, and we present an appropriate time-temperature curve for Korean subway tunnels. The ISO 834 curve was used as a fire design model and the temperature distribution in the tunnel was estimated using numerical analysis. This led to a proposal for effective measures against subway tunnel fires.

• Journal of the Korea institute for structural maintenance and inspection
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• v.14 no.3
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• pp.196-200
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• 2010

The number of railway tunnels has been increasing rapidly. Although fires in long railway tunnels are rare, the consequences can be devastating. Prior to this study, there were no adequate time-temperature curves for the fire safety assessment of Korean railway tunnels. We studied a standard foreign time-temperature curve for which the heat rate is based on the traffic and the types of vehicles. We then proposed a hydrocarbon curve as a fire design model for railway tunnels in Korea. We examined the implications of this proposed model on railway tunnel structures using numerical analysis.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.15 no.3
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• pp.65-76
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• 2005

Speeding up scalar multiplication of an elliptic curve point has been a prime approach to efficient implementation of elliptic curve schemes such as EC-DSA and EC-ElGamal. Koblitz introduced a $base-{\phi}$ expansion method using the Frobenius map. Kobayashi et al. extended the $base-{\phi}$ scalar multiplication method to suit Optimal Extension Fields(OEF) by introducing the table reference method. In this paper we propose an efficient scalar multiplication algorithm on elliptic curve over OEF. The proposed $base-{\phi}$ scalar multiplication method uses an optimized batch technique after rearranging the computation sequence of $base-{\phi}$ expansion usually called Horner's rule. The simulation results show that the new method accelerates the scalar multiplication about $20\%{\sim}40\%$ over the Kobayashi et al. method and is about three times as fast as some conventional scalar multiplication methods.

• Journal of the Korea institute for structural maintenance and inspection
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• v.25 no.6
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• pp.131-142
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• 2021

For old piers constructed when seismic design code had not been developed, lap splices usually exist in plastic hinge region. Corrosion of rebars causes decreasement in cross-sectional area of rebar and deterioration of lap-splice behaviour, thereby reducing the seismic performance of the old piers. In this research, according to these characteristics of old piers, test specimens are designed and manufactured considering rebar corrosion, lap splice, seismic design details, and seismic reinforcement. These effects are investigated through experiments. As a result of these experiment, rebar corrosion as well as lap splice reduces displacement ductility. When seismic design details or steel-plate reinforcement are applied, sufficient displacement ductility is expressed. For non-seismically designed specimens, loosening of the lap splice of transverse rebars caused buckling of longitudinal rebars and crushing of core concrete in plastic hinge region . For seismically designed specimen, area-reducing and untying of transverse rebars due to corrosion of rebars caused buckling of longitudinal rebars and crushing of core concrete.

• Journal of Mushroom
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• v.3 no.3
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• pp.100-104
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• 2005

We investigated mineral difference from mushroom Phellinus linteus and Phellinus baumii on mulberry, oak and elm. ICP test, The major mineral components were K, Ca, and Fe, while Mg, Na, P, Cr, Mn, Cu and Zn were determined as micro mineral components. In case of P.linetus and P.baumii the component of K was shown as 699.0mg/100g and 630mg/100g, in oak, 340.7mg/100g and 314.6mg/100g in elm, and 311.6mg/100g and 311.6mg/100g in mulberry respectively. In Ca, mulberry fruiting body were shown about 2 times highest and expecially in case of Na was oak fruiting body were shown as 10 times highest as against the others sample groups. In micro mineral components, Zn component was shown very diffeence about sample groups. We concluded that the highest mineral component of K was shown in mushroom cultivated on oak of both P.linetus and P.baumii. As a results, mineral component has showed very difference on cultivated to timber. According to the results of mineral component we concluded that Phellinus linteus and Phellinus baumii has mineral component different depending on timber.

• Journal of the Korean Applied Science and Technology
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• v.33 no.4
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• pp.802-812
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• 2016

Silicone foam is very useful as flame resistant material for many industrial areas such as high performance gasketing, thermal shielding, vibration mounts, and press pads. A silicone foam was prepared through simultaneous crosslinking and foaming by hydrogen condensation reaction of a vinyl-containing polysiloxane (V-silicone) and a hydroxyl-containing polysiloxane (OH-silicone) with hydride containing polysiloxane (H-silicone) in the presence of platinum catalyst and imorganic filler at room temperature. This is more convenient process for silicone foam manufacturing than the conventional separated crosslinking and foaming systems. Funtionalized silicones we used in this experiment were consisted with a V-silicone containing 1,0 meq/g of vinyl groups and a viscosity of 20 Pa-s, an OH-silicone with 0.4 meq/g of hydroxyl groups and a viscosity from 50 Pa-s, and an H-silicone containing 7.5 meq/g of hydride groups and a viscosity of 0.06 Pa.s. The effects of compositions of functionalized silicones and additives, such as catalyst and filler on the structure and mechanical properties of silicone foam were studied. 0.5 wt% of Pt catalyst was enough to accelerate the foaming rate of silicone resins. The addition of OH-silicone with lower viscosity accelerates the initial foaming rate and decreases the foam density, but the addition of V-silicone with lower viscosity reduces the tensile strength as well as the elongation. The final foam density, tensile strength, and elogation of silicone foam prepared under the SF-3 condition increase maximum to $0.58g/cm^3$, $3,51kg_f/cm^2$, and 176 %, repectively. We found out the filler alumina also played an important role to improve the mechanical properties of silicone foams in our foaming system.

• The Journal of the Acoustical Society of Korea
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• v.39 no.4
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• pp.351-363
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• 2020

Launch vehicles are subject to airborne acoustic loads during atmospheric flight and these effects become pronounced especially in transonic region. As the vibration due to the acoustic loads can cause malfunction of payloads, it is essential to predict and reduce the acoustic loads. In this study, a complete process has been developed for predicting airborne vibro-acoustic environment inside the payload pairing and subsequent noise reduction procedure employing acoustic blankets and Helmholtz resonators. Acoustic loads were predicted by Reynolds-Averaged Navier-Stokes (RANS) analysis and a semi-empirical model for pressure fluctuation inside turbulent boundary layer. Coupled vibro-acoustic analysis was performed using VA One SEA's Finite Element Statistical Energy Analysis (FE-SEA) hybrid module and ANSYS APDL. The process has been applied to a hammerhead launch vehicle to evaluate the effect of acoustic load reduction and accordingly to verify the effectiveness of the process. The presently developed process enables to obtain quick analysis result with reasonable accuracy and thus is expected to be useful in the initial design phase of a launch vehicle.

• (The)Study of the Eastern Classic
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• no.34
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• pp.387-414
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• 2009

This paper seeks to provide an overview on the newly-discovered manuscript in gasa style. It is significant in that the entire in gasa style has not been seen before, although occasionally scripts incorporate sijo or gasa as inserted songs. The author of this manuscript is believed to be Bae Hyung (裵珩: ?-?), who lived in Daegachon, Yongdu-Myun, Sunchon-Gun in Jeonra-Namdo Province. It is estimated that the manuscript was written in April of King Gojong 37 years (year 1900). This , so-called the Yang Jee-Uk Collection Script, applies Samdan Pyunun Daewoo Method (三段片言對偶法), using Jongbae style (縱排法) to over 27 pagesof the book. The author seems to have collected the main scenes of and changed them into gasa style. It is also possible to postulate that the author might have simply divided the lines to make it resemble the existing gasa style, as the original was already in the form of lyrics. There are a few mistakes found in the manuscript. They seem to have been made while the author was recording the sung P'ansori, rather than while copying from a different manuscript.

• 한국생물공학회:학술대회논문집
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• 2001.11a
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• pp.640-641
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• 2001

The mycelium of 3 edible mushrooms, Shizophyllum commune, pleurotus ostreatus, Tricholoma sp. was cultured in a liquid for the production of a fibrinolytic enzyme. Among them, Shizophyllum commune produced highest amount of the enzyme. The intramycelial production of the fibrinolytic enzyme by the culture of the Shizophyllum commune mycelium was approximately 6-fold higher than the extramycelial production. The carbon and nitrogen sources for the production of the enzyme were 1.5% corn steep liguor and 1.0% soytone, respectively, and optimal culture temperature and initial pH were $25^{\circ}C$ and pH 6, respectively.

• Aerospace Engineering and Technology
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• v.9 no.2
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• pp.204-209
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• 2010

The current status of the development of pyrostarters, which play a role as a turbo pump starter in liquid propellant propulsion systems by supplying pressurized gas to power turbines for engine start, has been introduced. Firstly, the development history is briefly summarized, and secondly the current technical status in core parts for the development of pryrostarters such as solid propellants, internal ballistics, rupture discs, and igniters are presented. The current technical achievements could make it feasible to fulfill the development requirements for pyrostarters.