• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.21 no.11
• /
• pp.1403-1412
• /
• 1997

When a high-speed railway train enters a tunnel, a compression wave is generated ahead of the train and propagates through the tunnel, compressing and accelerating the rest air in front of the wave. At the exit of the tunnel, an impulsive wave is emitted outward toward the surrounding, which causes a positive impulsive noise like a kind of sonic boom produced by a supersonic aircraft. With the advent of high-speed train, such an impulsive noise can be large enough to cause the noise problem, unless some attempts are made to alleviate its pressure levels. In the purpose of the impulsive noise reduction, the present study calculated the effect of porous walls on the compression wave propagating into a model tunnel. Two-dimensional unsteady compressible equations were differenced by using a Piecewise Linear Method. Calculation results show that the cavity/porous wall system is very effective for a compression wave with a large nonlinear effect. The porosity of 30% is most effective for the reduction of the maximum pressure gradient of the compression wave front. The present calculation results are in a good agreement with experimental ones obtained previously.

• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.20 no.12
• /
• pp.4036-4043
• /
• 1996

When a high-speed railway train enters a tunnel, a compression wave is generated ahead of the train and propagates along the tunnel, compressing and accelerating the rest air in front of the wave. At the exit of the tunnel, an impulsive wave is emitted outward toward the surrounding, which causes a positive impulsive noise like a kind of sonic boom produced by a supersonic aircraft. With the advent of high-speed train, such an impulsive noise can be large enough to cause the noise problem, unless some attempts are made to alleviate its pressure levels. In the purpose of the impulsive noise reduction, the present study tested the effect of porous walls on the compression wave propagating into a model tunnel. Experimental results were obtained using a shock tube with an open end. The results showed that the cavity/porous wall is very effective for the compression wave with a large nonlinear effect. The porosity of 30% is most effective for attenuation and pressure gradient reduction of the compression wave front. Also the impulsive noise reduction increases with increasing the length and height of the cavity, compared with the tunnel equivalent diameter.

• KIEAE Journal
• /
• v.17 no.3
• /
• pp.107-112
• /
• 2017

Purpose: Both silica gel and activated carbon black particles were adopted for use as PCM absorbed porous media applicable as construction materials. To investigate usable methods for absorbing PCM into the media, they were soaked into PCM and also tested for enhancement of PCM absorption into them. Method: To test PCM absorption into some porous media such as both ${\varphi}1{\sim}2mm$ and $10{\mu}m$ silica gels, and $50{\mu}m$ activated carbon black, $43^{\circ}C$ PCM was used as a laten heat material. The method, soaking into PCM was applied to this study, and the media were moderately rotated by centrifuge to have the extra PCM flow out. DSC analysis was conducted to investigate the melting and solidifying of the PCM absorbed into the porous media. Result: It was found that PCM was absorbed into the porous media by over 85 wt% of all particles. In addition, it was noted that the ultrasonic vibrator was accelerating the PCM absorption into the particles to three times higher speed than simple soaking. Centrifuge was adopted to remove extra PCM sticking on the particle surfaces and extra PCM was moderately removed from the surfaces of the particles. DSC analysis indicated that the latent heat of the absorbed PCM particles was 160 J/g, and the melting temperature was approximately $40^{\circ}C{\sim}50^{\circ}C$.

• KIISE Transactions on Computing Practices
• /
• v.22 no.8
• /
• pp.399-404
• /
• 2016

asm.js is a newly proposed language for overcoming the low performance of traditional Javscript language. asm.js is known as the subset of Javascript, and usually performs within only doubled slowdown over native compilation with clang. When programmers develop asm.js applications, they usually implement them via source-to-source compilation from C/C++. However, this application development process does not consider the cases where programmers need to develop asm.js applications from existing Javascript applications. To surmount the limitations in current development environment, we propose Javscript-to-asm.js compiler, which enables programmers to develop asm.js applications by using Javscript. By analyzing the result of our study, we demonstrate the efficiency and availability of the proposed compiler.

• Electronics and Telecommunications Trends
• /
• v.36 no.6
• /
• pp.1-12
• /
• 2021

As the demand for big data and big data-based artificial intelligence (AI) technology increases, the need for privacy preservations for sensitive information contained in big data and for high-speed encryption-based AI computation systems also increases. Fully homomorphic encryption (FHE) is a representative encryption technology that preserves the privacy of sensitive data. Therefore, FHE technology is being actively investigated primarily because, with FHE, decryption of the encrypted data is not required in the entire data flow. Data can be stored, transmitted, combined, and processed in an encrypted state. Moreover, FHE is based on an NP-hard problem (Lattice problem) that cannot be broken, even by a quantum computer, because of its high computational complexity and difficulty. FHE boasts a high-security level and therefore is receiving considerable attention as next-generation encryption technology. However, despite being able to process computations on encrypted data, the slow computation speed due to the high computational complexity of FHE technology is an obstacle to practical use. To address this problem, hardware technology that accelerates FHE operations is receiving extensive research attention. This article examines research trends associated with developments in hardware technology focused on accelerating the operations of representative FHE schemes. In addition, the detailed structures of hardware that accelerate the FHE operation are described.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.16 no.2
• /
• pp.1533-1540
• /
• 2015

In order to demonstrate the flow properties of the river bed and the design of hydraulic structures, the estimation of friction velocity is essentially required. However, existing friction velocity equations such as Log method and Power law have trouble to estimate the friction velocity because a boundary condition and various hydraulic properties are changed constantly in near the wall. In the present study, therefore, a new friction velocity equation that can minimize the parameters and reduce an error was suggested. To verify accuracy and reliability for the proposed equation, Clauser method, $\sqrt{gRI}$ method, reynolds stress method by Dr. Song were compared with the proposed method by estimated entropy parameter M for each channel. Consequently, the results show that uniform flow condition as well as non-uniform flow condition with highly accuracy nearly matched in case of accelerating non-uniform condition of $R^2=0.9621$, Decelerating Non Uniform condition of $R^2=0.9274$, Uniform condition of $R^2=0.8865$.

• Journal of Physiology & Pathology in Korean Medicine
• /
• v.25 no.5
• /
• pp.807-815
• /
• 2011

This study was designed to investigate the effects of Mokhyangjoki-san extract (MJS) on the improvement in cerebral blood flow (rCBF) in cerebral ischemic rats, and further to determine cytokines production (IL-1${\beta}$, TNF-${\alpha}$, IL-10, TGF-${\beta}$) of MJS. The results in cerebral ischemic rats were as follows ; The rCBF was significantly and stably increased by MJS (10 mg/kg, i.p.) during the period of cerebral reperfusion, which contrasted with the findings of rapid and marked increase in control group. In cytokine production in serum from femoral arterial blood 1 hr after middle cerebral arterial occlusion, MJS significantly decreased IL-1${\beta}$ and TNF-${\alpha}$ production, and increased IL-10 production compared with control group. In cytokine production in serum from femoral arterial blood 1 hr after reperfusion, MJS significantly decreased IL-1${\beta}$ and TNF-${\alpha}$ production compared with control group. IL-10 and TGF-${\beta}$1 production in MJS group were significantly increased compared with control group. These results suggested that MJS significantly and stably increased rCBF by inhibiting the production IL-1${\beta}$ and TNF-${\alpha}$, and accelerating that of IL-10 and TGF-${\beta}$. The result in nerve cells was as follows ; MJS significantly inhibited lactate dehydrogenase activity in vitro in a dose-dependent manner. This result suggested that MJS prevented the neuronal death.

• Journal of Physiology & Pathology in Korean Medicine
• /
• v.20 no.6
• /
• pp.1612-1619
• /
• 2006

This Study was designed to investigate the mechanism of Mixture of Bambusae Caulis in Liquamen and Bamboo Extract on the change of regional cerebral blood flow (rCBF) and blood pressure (BP) in normal rats, and further to investigate cytokines production in serum of cerebral ischemic rats. Mixture were as follows ; Bamboo Extract extracted with distilled water at 98 $^{\circ}C$ for 3 hrs, Mixture of Bambusae Caulis in Liquamen and bamboo Extracts (MLE) mixed at the ratio 1 to 100 (MLE100), 1 to 50 (MLE50), 1 to 20 (MLE20), 1 to 10 (MLE10), 1 to 5 (MLE5). The results were as follows ; The MLE-induced increase in rCBF was significantly inhibited by pretreatment with indomethacin (1 mg/kg, I.p.), an inhibitor of cyclooxygenase as well as methylene blue (10 $^{\mu}g/kg$, I.p.), an inhibitor of guanylate cyclase. The MLE-induced increase in BP was significantly inhibited by pretreatment with methylene blue. In cytokines production in the serum drawn from femoral arterial 1 hr after middle cerebral artery occlusion, MLE5 significantly increased production of TGF-${\beta}$ and increased production of IL-10, but significantly decreased production of TGF-${\alpha}$ compared with control group. In cytokines production in the serum drawn from femoral arterial 1 hr after reperfusion, MLE5 significantly increased production of TGF-${\beta}$ and IL-10, but significantly decreased production of TGF-${\alpha}$ compared with control group. AS results above. And MLE5 had anti-ischemic effect by inhibiting TGF-${\alpha}$ production, and by accelerating IL-10 and TGF-${\beta}$ production.

• Journal of Physiology & Pathology in Korean Medicine
• /
• v.21 no.5
• /
• pp.1127-1134
• /
• 2007

The study was designed to investigate the mechanism of Patholoobi Caulis freeze dried powder (PCF) on the regional cerebral blood flow (rCBF) and mean arterial blood pressure (MABP) in normal rats and cytokines production ($IL-1{\beta}$, $TNF-{\alpha}$, IL-10, $TGF-{\beta}$) in cerebral ischemic rats. The results in normal rats were as follows ; Increase of PCF-induced rCBF was significantly inhibited by pretreatment with methylene blue (10 ${\mu}g/kg$, I.p.), an inhibitor of guanylate cyclase, and was inhibited by indomethacin (1 mg/kg, i.p.), an inhibitor of cyclooxygenase. Increase of PCF-induced MABP was decreased by pretreatment with methylene blue, but was increased by indomethacin. These results suggested that the mechanism of action PCF was mediated by cyclic 3',5'-guanosine monophosphate. The results in cerebral ischemic rats were as follows ; In cytokine production in serum from femoral arterial blood 1 hr after middle cerebral arterial occlusion, PCF (10 mg/kg. i.p.) significantly decreased $IL-1{\beta}$ and $TNF-{\alpha}$ production, and increased IL-10 production compared with control group. In cytokine production in serum from femoral arterial blood 1 hr 1 hr after reperfusion, PCF (10 mg/kg, i.p.) significantly decreased $IL-1{\beta}$ production, and incresed IL-10 production compared with control group. These results suggested that PCF was significantly and stably increased regional cerebral blood flow by inhibiting $IL-1{\beta}$ production, and by accelerating IL-10 production.

• Journal of Korean society of Dental Hygiene
• /
• v.8 no.1
• /
• pp.119-131
• /
• 2008

This study was peformed in order to find out the relationship between the causing factors and the production of each gas 01 oral malodor, to contribute the oral malodor control at dental clinic as well as to establish the effective application of malodor control project for public oral health program 127 patients from 20 to 40 years old who had been visited for preventive dental cares were participated for the study. Such items as caries status, periodontal status, salivary flow, viscosity, pH. Snyder test, plaque deposit and tongue plaque were checked through the oral examination in order to find out the contributing factors Hydrogen sulfide, Methyl mercaptan, Di-methyl sulfide and Ammonia gas components were checked with Oral-Chroma and Attain, the oral malodor check units. Not only the corelation coefficiencies but also the multi-way variance analysis were calculated between each causing factor and each component of oral malodor gases to estimate the contributing factors of the oral malodor. 1. There was no relationship between the caries status and each component pf the oral malodor such as sulfur compound or Ammonia, both in laboratory test and VAS test (pF0.05). It revealed negative relationship between Hydrogen sulfide and FT(rM-0.1904. pE0.05) as well as the VAS and FT (rM-0.210. pE0.05). S0, it was estimated that the less oral malador was recognized when caries state changed to filled state in Hydrogen sulfide laboratory test or VAS test 2. High relationship was showed between salivary flow and Hydrogen sulfide (rM-0.183, pM0.039), Methyl mercaptan(rM-0.234, p-0.008). Dimethyl sulfide(rM-0.234, pM0.008) and Ammonia(-0.361. pM0.001) gas(pE0.05). 3. There was a high relationship between M-PHP(Modified-Patient Hygiene Performance Index) and tong plaque all kinds of sulfide(rM0.249. pM0.005). Ammonia gas component(rM0.232, pM0.009). 4. It was found that considerable relationship was appeared between the periodontal status and Ammonia gas (rM0.274, pM0.002), so, it should be needed to control Ammonia. Such dental Cares as the prevention or early treatment of periodontal disease and the accelerating the salivary flow as well as reducing the amounts and activities of filament or spiral typed oral micro-organism were recommended for adults, not only for dental care program at the dental clinics but also for public health programs, in order to promote the oral health and quality of file for individual and community peoples.