• Journal of the Institute of Electronics Engineers of Korea TC
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• v.46 no.5
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• pp.36-47
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• 2009

There exists RFID reader-to reader frequency which can not recognize tag in dense reader nude because the interference causes low SIR. To solve this frequency, the many algorithms based on TDM have been proposed. But the most of existing algorithms not obtain the optimal time allocation but propose heuristic scheduling algorithm. In this paper, we apply game theory which deals with interest between players of game to RFID reader-to reader interference and analyze the time allocation problem of reader based on TDM in terms of cooperative game which the players bind agreements using Nash Bargaining Solution(NBS) and non-cooperative game which the players do not bind agreements using Nash Equilibrium(NE). The applied results show that in dense reader mode, NBS of cooperative game is superior to NE of non-cooperative game and present optimal time allocation in dense reader mode.

• 보존과학연구
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• s.30
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• pp.63-77
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• 2009

Scientific studies of conservation techniques and materials in Korea have experienced fast development since international practice and academic knowledge have been introduced to Korea from Japan, France, Germany, and etc from the late 1960s. In recent years, it has been observed that the academic standard of research and the level knowledge of the field in Korea at present are far advanced to compete with many countries. However, many Korean cases still have displayed that the standard and the quality of conservation practice need to be improved. This research examined several cases of derelict restoration of metal relics executed by non-conservators and the effects of their ignorant use of irreversible materials on the valuable objects. The purpose of the study is to display the problem of such treatments and to suggest a need of framework to prevent the loss of original form from them. Metal Buddha statue (Cosmic Buddha) in Borim Temple (National Treasure No. 117), which was conserved by an unexperienced non-conservator, has suffered from a serious problem of corrosion because of the use of destructive material, iron chloride. Another case for metal Buddha statue in Dopian Temple (National Treasure No. 63) displays a representative example of using irreversible materials, Cashew and such ignorant application made a later conservation treatment so difficult in removing the material from the surface of the statue. In conclusion, the research argued that the understanding of materials used in the objects, and the value of relics is important, and pre-experiments before applying conservation materials to a valuable heritage are essential in the conservation treatment.

• Restorative Dentistry and Endodontics
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• v.20 no.1
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• pp.235-249
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• 1995

This study was designed to identify the lymphocytes present and to examine the relation between lymphocytes population and clinical symptoms of the pulps clinically diagnosed as normal and irreversible pulpitis. We recorded the history and severity of the pain and performed several clinical tests, before extirpation of vital, irreversibly inflamed pulps in routine endodontic treatment. Then the teeth were divided into two groups. Five teeth, categorized in acute symptom group, had severe spontaneous pain, particularly at night and were extremely sensitive to cold and heat. The other 15 teeth with history of mild to moderate pain and with or without cold or heat responses were categorized as chronic symptom group. Inflamed pulps were also classified into 8 minor groups by presence or absence of signs or symptoms related to the involved teeth, including the presence of pain on percussion, pain on heat and cold stimuli and the periodontal pocket depth. All extirpated pulps were immediately immersed in ultra low-temperature freezer($-74^{\circ}C$), and they were sectioned $6{\mu}m$ in thickness. Specimens were stained using three-stage indirect immunoperoxidase techniques(DAKO, LSAB kit) and monoclonal antibodies for detecting the presence of T lymphocytes(T), B lymphocytes(B) and helper(T4) and suppressor(T8) lymphocytes. Following results were obtained; 1. All the examined normal and inflamed pull) tissues had positive staining for T lymphocytes and T helper and T suppressor cells. But B cells were observed only in inflamed pulp. 2. Statistically more T and B cells were observed in acute symptom group as compared with chronic symptom group(p<0.05). 3. Cell ratio of BIT in acute symptom group were significantly higher than that of chronic symptom group(p<0.05). 4. Only B cells were significantly increased in the percussion positive group than the number of B cells in percussion negative group(p<0.05). 5. No differences were observed in the number of different cell types among other minor groups.

• Journal of Conservation Science
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• v.26 no.2
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• pp.183-190
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• 2010

We fabricated urethane material based on properties of reversible and unfading for antic-ceramics restoration. This material with low viscosity was made hardness control possible that user want. And it have very strong adhesion and shear strength properties and is shown the best properties for pigment filling, anti-contractibility, coloring as like epoxy system materials. Particularly, the yellowing and ir-reversibility problem in epoxy restoration material were finally solved. So, there is guarantee in the eternity and stabilization of restoration for antic-celamics. And in order to show the reversible state of the restoration, we successfully dissolve this urethane materials in solvent after perfect restoring subsequently.

• Applied Chemistry for Engineering
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• v.23 no.4
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• pp.359-366
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• 2012

Zn-Air energy storage cell is an attractive type of batteries due to its theoretical gravimetric energy density, cost-effective structure and environmental-friendly characteristics. The chargeability is the most critical in various industrial applications such as smart portable device, electric vehicle, and power storage system. Thus, it is necessary to reduce large overpotential of oxygen reduction/evolution reaction, the irreversibility of Zn anode, and carbonation in alkaline electrolyte. In this review, we try to introduce recent studies and developments of bi-functional air cathode, enhanced charge efficiency via modification of Zn anode structure, and blocking side reactions applying hybrid organic-aqueous electrolyte for high power density rechargeable Zn-Air energy storage cells.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.17 no.4
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• pp.285-296
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• 2005

In order to reduce the compression power and to use the overall energy contained in LNG effectively, a combined cycle is devised and simulated. The combined cycle is composed of two cycles; one is an open cycle of liquid/solid carbon dioxide production cycle utilizing LNG cold energy in $CO_2$ condenser and the other is a closed cycle gas turbine which supplies power to the $CO_2$ cycle, utilizes LNG cold energy for lowering the compressor inlet temperature, and uses the heating value of LNG at the burner. The power consumed for the $CO_2$ cycle is investigated in terms of a production ratio of solid $CO_2$. The present study shows that much reduction in both $CO_2$ compression power (only $35\%$ of power used in conventional dry ice production cycle) and $CO_2$ condenser pressure could be achieved by utilizing LNG cold energy and that high cycle efficiency ($55.3\%$ at maximum power condition) in the gas turbine could be accomplished with the adoption of compressor inlet cooling and regenerator. Exergy analysis shows that irreversibility in the combined cycle increases linearly as a production ratio of solid $CO_2$ increases and most of the irreversibility occurs in the condenser and the heat exchanger for compressor inlet cooling. Hence, incoming LNG cold energy to the above components should be used more effectively.

• Journal of the Korean Chemical Society
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• v.38 no.8
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• pp.590-597
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• 1994

The chemical behavior of the trivalent lanthanide$(Pr^{3+}, Eu^{3+}, Gd^{3+} 그리고 Yb^{3+})$complexes with organo-ligand (2,2,6,6-tetramethyl-3,5-heptanedione) has been investigated by the use of UV/Vis-spectrophotometric, magnetics, and electrochemical method. The two or three energy absorption bands are observed by the spectra of these complexes. The magnetitude of crystal field splitting energy, the spin pairing energy and bond stength was obtained from the spectra of the complexes. These are found to be localization, low-spin (or high-spin state, and strong bonding strength. The magnetic dipole moment are found to be diamagnetic complexes (or paramagnetic). The electrochemical behavior of complexes was observed by the use of cyclic voltammetry in aprotic media. These reduction peaks were irreversible two and three step reduction processes by electron transfer.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.44 no.6
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• pp.16-23
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• 2007

Changeable biometrics has been developed as a solution to problem of enhancing security and privacy. The idea is to transform a biometric signal or feature into a new one for the purposes of enrollment and matching. In this paper, we propose a changeable biometric system that can be applied to appearance based face recognition system. In the first step when using feature extraction, ICA(Independent Component Analysis) coefficient vectors extracted from an input face image are replaced randomly using their mean and variation. The transformed vectors by replacement are scrambled randomly and a new transformed face coefficient vector (transformed template) is generated by combination of the two transformed vectors. When this transformed template is compromised, it is replaced with new random numbers and a new scrambling rule. Because e transformed template is generated by e addition of two vectors, e original ICA coefficients could not be easily recovered from the transformed coefficients.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.28 no.6
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• pp.1607-1621
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• 2018

The financial industry, which guarantees a credible transaction and can not permit forgery of its transaction information, has hitherto adhered to a traditional centralized ledger management method. However, the blockchain technology has a decentralization which has been regarded as unsafe for the time being, and the more reliable transaction agreement and data integrity are guaranteed The world's financial industry and the IT world is causing the wave. Nevertheless, the inherent characteristics of the blockchain, such as the irreversibility of block information within a blockchain and the sharing of blocks between blockchain participants, can not avoid conflicts with the privacy laws. The purpose of this study is to investigate the problems related to deletion and the third party supply of personal information by focusing on these characteristics of the blockchain and to suggest the technical alternatives of the applicable blockchain and the improvement direction of the personal information protection law for using of blockchain technology.

• Journal of Internet Computing and Services
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• v.20 no.4
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• pp.1-11
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• 2019

A Blockchain-based access control technology is one of the various use cases of blockchain and is used in many areas to transparently transfer and manage ownership of data between users without the trusted third party. The characteristics of transparency, Irreversibility, and decentralization provided by the public blockchain help to offer new benefits that existing access control technologies did not offer. However, various security issues facing the current blockchain are raising the issue of the safety of the technology. Therefore, in this paper, we analyze an overview of the blockchain-based access control technology and solutions of the security challenges faced. Moreover, we further present solutions that are not affected by the blockchain trilemma and models of access control technology based on them.