• International Journal of Industrial Entomology and Biomaterials
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• v.17 no.1
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• pp.137-141
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• 2008

We previously isolated and cloned a cDNA of abaecin from the Bombus ignitus. In an effort to produce a large amount of soluble abaecin at low cost, we successfully expressed the peptide in Escherichia coli that are highly sensitive to its mature form. For this, we fused the peptide encoding 39 amino acids of mature B. ignitus abaecin to the thioredoxin gene together with a C-terminal 6xHis tag. An enterokinase cleavage site was introduced between the 6xHis tag and mature abaecin to allow final release of the recombinant peptide. A high yield of 9.6 mg soluble fusion protein from 200 ml of bacterial culture was purified by $Ni^{2+}$-charged His-Bind resin affinity column, and 1.4 mg of pure active recombinant abaecin was readily obtained by enterokinase cleavage, followed by affinity chromatograph. The molecular mass of recombinant abaecin peptide was determined by Tricin-SDS-PAGE analysis. The recombinant abaecin exhibited antibacterial activity against Gram-negative bacteria.

• The KIPS Transactions:PartC
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• v.16C no.3
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• pp.325-334
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• 2009

This paper demonstrates that an attacker can impersonate a random RFID tag and then perform the spoofing attack in the previous RFID authentication protocol. To resolve such a security problem, we also propose a new secure and efficient RFID mutual authentication protocol. The proposed RFID mutual authentication protocol is not only to resolve many security problems with the existing RFID authentication mechanism and the vulnerability against spoofing attack, but also to guarantee reliable authentication time as reducing computational overhead performing by tag. As a result, the proposed RFID mutual authentication protocol provides stronger security including the forward secrecy and more efficiency.

• Proceedings of the Materials Research Society of Korea Conference
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• 2010.05a
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• pp.19.1-19.1
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• 2010

The process of manufacturing printed electronics using printing technology is attracting attention because its process cost is lower than that of the conventional semiconductor process. This technology, which offers both a lower cost and higher productivity, can be applied in the production of organic TFT (thin film transistor), solar cell, RFID(radio frequency identification) tag, printed battery, E-paper, touch screen panel, black matrix for LCD(liquid crystal display), flexible display, and so forth. In general, in order to implement printed electronics, narrow width and gap printing, registration of multi-layer printing by several printing units, and printing accuracy of under $20\;{\mu}m$ are all required. These electronic products require high precision to the degree of tens of microns - in a large area with flexible material, and mass productivity at low cost. As such, the roll-to-roll printing process is attracting attention as a mass production system for these printed electronic devices. For the commercialization of this process, two basic electronic ink technologies, such as conductive ink and polymers, and printing equipment have to be developed. Therefore, this paper addressed basis design and test to develop fine patterning equipment employing the roll-to-roll printing equipment and electronic ink.

• KIISE Transactions on Computing Practices
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• v.21 no.4
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• pp.283-289
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• 2015

We propose a low cost attendance checking system using NFC (Near Field Communication) and show a case study of an actual operation of the system in a higher education institute. The system offers a direct attendance check service when a student touches NFC tag on a classroom desk with his/her own smartphone. Our service was first developed and operated in 2012, and then additional functions like massive real time processing were reinforced. In the fall semester, 58 courses use the service and 96% of the class attendance was checked with mobile devices. The only hardware requirement of the system was NFC tag on the classroom desk, which reduced hardware cost dramatically. However, it also minimized attendance checking time into 1 minute regardless of enrolled student number.

• Journal of Microbiology and Biotechnology
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• v.30 no.7
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• pp.1072-1081
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• 2020

Screening suitable strains with high temperature adaptability is of great importance for reducing the cost of temperature control in microalgae cultivation, especially in summer. To obtain high temperature-tolerant diatoms, water samples were collected in summer from 7 different regions of China across the Northeast, North and East. A total of 731 water samples was collected and from them 131 diatom strains were isolated and identified based on the 18S rRNA sequences. Forty-nine strains out of the 131 diatoms could survive at 30℃, and 6 strains with relatively high biomass and lipid content at high temperature were selected and were found to be able to grow at 35℃. Cyclotella sp. HB162 had the highest dry biomass of 0.46 g/l and relatively high triacylglycerol (TAG) content of 237.4 mg/g dry biomass. The highest TAG content of 246.4 mg/g dry biomass was obtained in Fistulifera sp. HB236, while Nitzschia palea HB170 had high dry biomass (0.33 g/l) but relatively low TAG content (105.9 mg/g dry biomass). N. palea HB170 and Fistulifera sp. HB236 presented relatively stable growth rates and lipid yields under fluctuating temperatures ranging from 28 to 35℃, while Cyclotella HB162 maintained high lipid yield at temperatures below 25℃. The percentage of saturated fatty acids and monounsaturated fatty acids in all the 6 strains was 84-91% in total lipids and 90-94% in TAGs, which makes them the ideal feedstock for biodiesel.

• The KIPS Transactions:PartC
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• v.11C no.6 s.95
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• pp.851-862
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• 2004

RFID(Radio frequency IDentification) is a technology that automatically identifies objects containing the electronic tags by using radio wave. The multi-tag identification problem is the core issue in the RFID and could be resolved by the anti-collision algorithm. However, most of the existing anti-collision algorithms have a problem of heavy implementation cost and low performance. In this paper. we propose a new tree based memoryless anti-collision algorithm called a collision tracking tree algorithm and presents its performance evaluation results obtained by simulation. The Collision Tracking Tree algorithm proves itself the capability of an identification rate of 749 tags per second and the performance evaluation results also show that the proposed algorithm outperforms the other two existing tree-based memoryless algorithms, i.e., the tree-walking algorithm and the query tree algorithm about 49 and 2.4 times respectively.

• Journal of KIISE:Computing Practices and Letters
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• v.15 no.6
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• pp.425-429
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• 2009

Recently, Chen et al.'s proposed mutual authentication scheme based on the quadratic resiidue, finding the squaring root problem, for avoiding exhaustive search on the server. But, if a malicious reader sends same random value, the tag is traced by an adversary. Moreover, there is realization problem because of its limited ability to compute squaring and hash function. In this paper, we analyze Chen et al.'s scheme and its weakness. Furthermore we present an improved mutual authentication scheme based on the quadratic residue which solves the tracing problem by generating random value on the tag and uses only squaring. We also make the scheme satisfy to forward secrecy without updating and synchronizing and avoid exhaustive search.

• Journal of the Korean Society for Precision Engineering
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• v.25 no.11
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• pp.90-94
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• 2008

Recently, a great deal of research is focused on the printed electronics. One of their mainly concerned products is printed RFID tag. RFID technology has attracted researchers and enterprises as a promising method for automatic identification, and they are expected to replace conventional bar codes in inventory tracking and management. The key to successful RFID technology lies in developing low-cost RFID tags and the first step in applying printing technology to RFID systems is to replace antennas that are conventionally produced by etching copper or aluminum. However, due to the printing quality variations, errors, and lower conductivity, the performance of the printed RFID antennas is lower than that of antennas manufactured by conventional etching methods. In this paper, the effect of variations in the printing conditions on the antenna performance is investigated. Three levels for each condition parameter is assumed and effect on the resonant frequency are examined experimentally based on orthogonal array. The most serious factor that affects the resonant frequency of the antenna is the non-uniformity of the edge and the resonant frequency is found to be lower as the non-uniformity increases.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.36 no.6B
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• pp.618-630
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• 2011

Mobile RFID system, that consists of the existing RFID reader mounted on the mobile devices such as smartphones, is able to provide the users a variety of services and convenience. Although the users can get the information about a certain product anytime anywhere, there is high probability that their privacy may be violated because their belongings with RFID tags can be scanned by other mobile readers at any time. Several RFID authentication schemes have been proposed to deal with these privacy issues. However, since the existing solutions require heavy computation on the tag side, most of them is not applicable to the general low-cost passive tags which do not have any processing unit. In this paper, we propose the efficient authentication scheme for mobile RFID system applicable to the passive tags as well as the active ones by the best use of computing capability of mobile devices. The proposed scheme satisfies the import security issues such as tag protection, untraceability, anti-traffic analysis. We also implement the proposed scheme on top of real smartphone for feasibility and show the experimental results from it.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.20 no.1
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• pp.63-72
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• 2010

RFID is one of useful identification technology in ubiquitous environments which can be a replacement of bar code. RFID is basically consisted of tag, reader, which is for perception of the tag, and back-end-database for saving the information of tags. Although the usage of mobile readers in cellular phone or PDA increases, related studies are not enough to be secure for practical environments. There are many factors for using mobile leaders, instead of static leaders. In mobile reader environments, before constructing the secure protocol, we must consider these problems: 1) easy to lose the mobile reader 2) hard to keep the connection with back-end-database because of communication obstacle, the limitation of communication range, and so on. To find the solution against those problems, Han et al. suggest RFID mutual authentication protocol without back-end-database environment. However Han et al.'s protocol is able to be traced tag location by using eavesdropping, spoofing, and replay attack. Passive tag based on low cost is required lots of communication unsuitably. Hence, we analyze some vulnerabilities of Han et al.'s protocol and suggest RFID mutual authentication protocol without online back-end-database in aspect of efficiency and security.