• Journal of the Korea Society of Computer and Information
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• 제16권11호
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• pp.163-171
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• 2011

Because RFID systems use radio frequency, they have many security problems such as eavesdropping, location tracking, spoofing attack and replay attack. So, many mutual authentication protocols and cryptography methods for RFID systems have been proposed in order to solve security problems, but previous proposed protocols using AES(Advanced Encryption Standard) have fixed key problem and security problems. In this paper, we analyze security of proposed protocols and propose our protocol using OTP(One-Time Pad) and AES to solve security problems and to reduce hardware overhead and operation. Our protocol encrypts data transferred between RFID reader and tag, and accomplishes mutual authentication by one time random number to generate in RFID reader. In addition, this paper presents that our protocol has higher security and efficiency in computation volume and process than researched protocols and S.Oh's Protocol. Therefore, our protocol is secure against various attacks and suitable for lightweight RFID tag system.

• Journal of the Society of Naval Architects of Korea
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• 제56권6호
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• pp.515-522
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• 2019

Since Liquefied Natural Gas (LNG) is normally carried at 1.1 bar pressure and at -163℃, special Cargo Containment System (CCS) are used. As LNG carrier is becoming larger, typical LNG insulation systems adopt a method to increase the thickness of insulation panel to reduce sloshing load and Boil-off Rate (BOR). However, this will decrease LNG cargo volume and increase insulation material costs. In this paper, silica aerogel, glass bubble were synthesized in polyurethane foam to increase volumetric efficiency by improving mechanical and thermal performance of insulation. In order to increase dispersibility of particles, ultrasonic dispersion was used. Dynamic impact test, quasi-static compression test at room temperature (20℃) and cryogenic temperature (-163℃) was evaluated. To evaluate the thermal performance, the thermal conductivity at room temperature (20℃) was measured. As a result, specimens without ultrasonic dispersion have a little effect on strength under the compressive load, although they show high mechanical performance under the impact load. In contrast, specimens with ultrasonic dispersion have significantly increased impact strength and compressive strength. Recently, as the density of Polyurethane foam (PUF) has been increasing, these results can be a method for improving the mechanical and thermal performance of insulation panel.

• Archives of Pharmacal Research
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• 제24권3호
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• pp.207-210
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• 2001

A fully automated high performance liquid chromatography with column-switching was developed for the simultaneous determination of KR60436, a new reversible proton pump inhibitor, and its active metabolite O-Demethyl-KR60436 from rat plasma samples. Plasma sample (50$\mu$l) was directly introduced onto a Capcell Pak MF Ph-1 column ($10{\times}4$ mm I.D.) where primary separation was occurred to remove proteins and concentrate target Substances Using acetonitrile-Potassium Phosphate (PH 7, 0.1 M) (2 : 8, v/v). The drug molecules eluted from MF Ph-1 column were focused in an intermediate column ($10{\times}2$ I.D.) by the valve switching step. The substances enriched in intermediate column were eluted and separated on a Vydac 218MR53 column ($250{\times}3.2$ I.D.) using acetonitrilepotassium phosphate (pH 7, 0.02 M) (47:53, v/v) at a flow rate of 0.5 ml/min when the valve status was switched back to A position. The method showed excellent sensitivity (detection limit of 2 ng/ml) with small volume of samples ($50{\mu}$l), good precision and accuracy, and speed (total analysis time 24 min) without any loss in chromatographic efficiency. The response was linear ($r^2{\geq}0.797$) over the concentration range of 5-500 ng/ml.

• Membrane Journal
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• 제21권4호
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• pp.351-359
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• 2011

For advanced drinking water treatment of high turbidity water, we used the hybrid process that was composed of photocatalyst packing in space of between outside of multi-channel ceramic microfiltration membrane and membrane module inside. Photocatalyst was polypropylene (PP) beads coated $TiO_2$ powder by CVD (chemical vapor deposition) process. Instead of natural organic matters (NOM) and fine inorganic particles in natural water source, standard NOM solution was prepared with humic acid and kaolin. Water-back-flushing of 10 sec was performed per every period of 10 min to minimize membrane fouling. Resistance of membrane fouling ($R_f$) increased and J decreased as concentration of humic acid changed from 2 mg/L to 10 mg/L, and finally the highest total permeate volume ($V_T$) could be obtained at 2 mg/L. Then, treatment efficiency of turbidity and $UV_{254}$ absorbance were above 96.4% and 78.9%, respectively. As results of treatment portions by membrane filtration, photocatalyst adsorption, and photo-oxidation in (MF), (MF + $TiO_2$), (MF + $TiO_2$ + UV) processes, turbidity was treated little by photocatalyst adsorption, and photo-oxidation. However, treatment portions of $UV_{254}$ absorbance by adsorption (MF + $TiO_2$) and photo-oxidation (MF + $TiO_2$ + UV) at humic acid of 4 mg/L and 6 mg/L were above 9.0, 9.5 and 8.1, 10.9%, respectively.

• KSBB Journal
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• 제21권1호
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• pp.28-33
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• 2006

A sewage was treated using a horizontal flow zeolite-filled reed bed. The sewage from the student dormitory of Changwon National University was fed into the reed bed for 10 minutes every 6 hours at the hydraulic load of $314L/m^2$ day. The filtering height of the reed bed was 100 cm and the zeolite mixture was filled in the reed bed. The mixture consisted of the same volume of two types of zeolite : $0.5{\sim}1mm$ and $1{\sim}3mm$ in diameter. Annual average removal efficiency was SS $88.5%,\;COD_{cr},\;86.1%,\;COD_{Mn}\;81.0%,\;T-N\;48.6%,\;NH_4^+-N\;97.1%$ and T-P 42.8%. T-N of effluent was mostly $NO_3^--N$ and the concentration of $NO_2^--N$ in effluent was lower than 0.1 mg/L. All removal efficiencies did not show a remarkable seasonal change.

• The Journal of Korean Institute of Communications and Information Sciences
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• 제36권3B호
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• pp.220-230
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• 2011

Mobile RFID which integrates mobile network with RFID technique is the technique to get the information of products by transmitting the identifier through mobile network after reading the identifier of RFID tag. It attached on the equipment as the mobile phone. However, mobile RFID has the privacy-related problem among requested secure problems required from the existing RFID. In this paper, the random key created by mobile RFID reader and Tag during the inter-certificating and initialization procedure for mobile RFID users to receive tag information from backend server securely is divided into random sizes and any information on the tag which requires the protection of privacy shouldn't be provided to anyone. In performance analysis, previous protocol used modulo operation in registration and login computation. But the proposed protocol has higher efficiency in saving space and computation volume than MARP scheme and Kim. et. al scheme because our protocol is accomplished by mutual authentication and registering user information through one-way hash function.

• Journal of Environmental Health Sciences
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• 제34권4호
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• pp.316-326
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• 2008

The Earth's temperature has risen $0.76^{\circ}C$ (degree) during last 100 years which Implies a sudden rise, compare with the 4oC (degrees) rise through out the past 20,000 years. If the volume of GHG (Greenhouse Gas) emission continues at the current level, the average temperature of the Earth will rise by $1^{\circ}C$ (degree) by 2030 with the further implication that the temperature of Earth will rise by $2{\sim}5^{\circ}C$ (degrees) every 100 years. Therefore, as we are aware that the temperature of the glacial epoch was $8{\sim}9^{\circ}C$ (degrees) lower than the present time, we can easily predict that the above temperature rises can be potentially disastrous for human life. Every country in the world recognizes theseriousness of the current climate change and adopted a convention on climate change in June 1992 in Rio. The COP1 was held in March 1995 in Berlin and the COP3 in Dec. 1997 in Kyotowhere the target (2008-2012) was determined and the advanced nations' reduction target (5.2%, average)was also agreed at this conference. Korea participated in the GHG reduction plan which required the world's nations to ratify the Kyoto Protocol. Ratification of the Kyotoprotocol and the followup requirement to introduce an international emissions trading scheme will require severe reductions in GHGs and considerable economic consequences. USA are still refusing to fully ratify the treaty as the emission reductions could severely damage the economies of these countries. In order to estimate the exact $CO_2$ emission, this study statistically analyzed $CO_2$ emission of each country based on the following variables : level of economic power and scientific development, the industrial system, productivity and energy efficiency.

• Carbon letters
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• 제27권
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• pp.64-71
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• 2018

$TiO_2$-doped activated carbon fibers (ACFs) were successfully prepared as capacitive deionization (CDI) electrode materials by facile ultrasonication-assisted process. ACFs were treated with titanium isopropoxide (TTIP) and isopropyl alcohol solutions of different concentrations and then calcinated by ultrasonication without heat-treatment. The results show that a certain amount of anatase $TiO_2$ was present on the ACF surface. The specific capacitance of the $TiO_2$-doped ACF electrode was remarkably improved (by 93.8% at scan rate of $50mV\;s^{-1}$) over that of the untreated ACF electrode, despite decreases in the specific surface area and total pore volume upon $TiO_2$ doping. From the CDI experiments, the salt adsorption capacity and charge efficiency of the sample with TTIP percent concentration of 15% were found to considerably increase by 71.9 and 57.1%, respectively. These increases are attributed to the improved wettability of the electrode, which increases the number of surface active sites and facilitates salt ion diffusion in the ACF pores. Additionally, the Ti-OH groups of $TiO_2$ act as electrosorption sites, which increases the electrosorption capacity.

• Transactions of the Korean Society of Mechanical Engineers
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• 제13권4호
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• pp.771-779
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• 1989

Numerical analysis by SIMPLE algorithm has been performed to predict the characteristics of flow and heat transfer in channels between the printed circuit boards of an electronic cabinet. It is assumed that the electronic parts release uniform heat flux per unit axial length to the cooling air. The air flow between channels is assumed fully developed laminar, incompressible, and mixed convective. In this study, the electronic parts are mounted on both sides of the prinked circuit boards by two kinds of configuration such as the zig-zag and the symmetric one. The Rayleigh numbers ranging from 0 to 10$^{6}$ are considered to predict the characteristics of the main flow and the secondary flow occurred by natural convection, the temperature distribution in channel, the heat transfer rate from heated electronic parts and the increase of friction factor by natural convection. As the results of numerical calculation, several conclusions are drawn as follows. The influence of natural convection on the flow characteristics appears strong when the Rayleigh number is above 10$^{4}$. The main axial flow rate decreases by a half or more at the Rayleigh number of 10$^{6}$ . Although the friction factor increases as Rayleigh number increases, the increasing rate of heat transfer is higher than that of the friction factor. The cooling efficiency of the zig-zig-configuration is superior to that of the symmetric configuration at same Rayleigh number.

• Korean Journal of Food Science and Technology
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• 제29권6호
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• pp.1202-1207
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• 1997

Inactivation of Leuconostoc sp. isolated from kimchi using carbon dioxide under pressure was investigated in terms of operating parameters in order to evaluate its feasibility as a novel nonthermal process. Inactivation rates increased with increasing pressure, temperature and exposure time, but with decreasing working volume. Microbial reduction of 3 log cycles was achieved within 150 min under a $CO_2$ pressure of $60\;kg/cm^2$ at 30^{\circ}C$. It was confirmed that microbial inactivation by the high pressure $CO_2$ was governed essentially by the characteristic of $CO_2$ mass transfer and thus penetration of $CO_2$, into cells was a rate limiting step to determine efficiency of the inactivation process. The experimental results suggested that the high pressure $CO_2$ treatment could be used as one of the effective nonthermal methods for preserving foods.