• Applied Chemistry for Engineering
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• v.9 no.2
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• pp.232-237
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• 1998

This study was carried out to find the optimal operating conditions for separation of residual uranium from the simulated radwaste solution containing 19 elements, and to evaluate the validity of the process. The selected process was based on the solvent extraction with TBP(tributyl phosphate). As an extractor, two miniature mixer-settlers with a total of 18 stages were used. Extraction yield of U, Np and Tc was about 99.2%. 32.1%, and 99.9%, respectively. The other elements were coextracted in the range of 1~4%. Extraction yield of U exceeded those of the previous work performed with batch system, which resulted in the low extractability of U (about 80%) according to the coexisting element such as Nd and Fe. It was due to the characteristics of multi-stage extractor. On the other hand, low extractability of Np was caused by various oxidation states in the nitric acid medium. In the case of Tc, its high extractability may be attributed to the complex formation with Zr and U, which is not well proved yet. All elements extracted with TBP were stripped into aqueous phase more than 99% by 0.01M $HNO_3$. From the results, this process has no problem with respect to in the same step was required, because Np was distributed in the raffinate and U product, respectively.

• KSBB Journal
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• v.9 no.3
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• pp.332-338
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• 1994

Solubilization phenomena of a protein in a reversed micellar solution were investigated and a hollow fiber membrane extractor was tested for reversed micellar protein extraction equipment. Alkaline protease was used as a model protein compound and the reversed micellar solution was consisted of AOT and isooctane. It was found that protein solubilization was strongly influenced by ionic strength and pH. The distribution coefficient of the protease between the aqueous solution and the AOT/isooctane solution was also observed to be as high as 4.0 within the scope of this experiment. A hollow fiber membrane extractor was constructed and tested for the protein extraction. The overall mass transfer coefficient at a typical experimental condition of this study was observed to be $6.7{\times}10^{-5}cm/s$. It was also found that the mass transfer resistance on reversed micellar solution was the dominant resistance for the protein transfer.

• Korean Chemical Engineering Research
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• v.45 no.3
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• pp.234-241
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• 2007

To achieve safe operation and to improve economics it is imperative to monitor and analyse demand and supply of utilities and to meet utility needs in time. The main objective of motor/turbine processes is to manipulate steam and electricity balances in utility plants. The optimal operation of motor/turbine processes is by far the most important to improve economics in the utility plant. In order to analyse motor/turbine processes, we need steady state models for steam generation equipments and steam distribution devices as well as turbine generators. In addition heuristics concerning various operational situations are required. The motor/turbine optimal operation system is based on utility models and operational knowledgebase and provides optimal operating conditions when the amount of steam demand from various steam headers is changed frequently. The optimal operation system also produces optimal selection of driving devices for utility pumps to reduce operating cost.

• Journal of the Korean association of regional geographers
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• v.21 no.1
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• pp.137-152
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• 2015

The purpose of this research is to reveal the problems of the Western based development discourse, and to derive the future direction of postdevelopment as sustainable development. This study attempted to reveal the historical process of formation and change on development discourse. Development generally regarded as the overcome of underdevelopment, inducing the marginalization of the South as a place to follow the development model of the North. State based development discourse (Keynesian development discourse) focused on the growth by industrialization, and the supreme aim of the South was to overcome the underdevelopment. Neoliberalism development discourse emphasized on the market principle based on free competition which was recognized as the best way to provide development. However, neoliberalism discourse has been criticized for the concentration of power and inequality of class, causing on the consideration of postdevelopment because of its emphasis on growth rather than distribution and life value. This research revealed the ways of postdevelopment with fair trade and ethical consumption. However, fair trade and ethical consumption discourses clearly show somewhat limitation subsuming into neoliberal development discourse. In this respect, future ways for postdevelopment have to consider the overcoming of powers based on market and capital, and to orient into the value of redistribution in development process.

• Journal of the Korean Vacuum Society
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• v.18 no.3
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• pp.176-185
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• 2009

The realization and the performance of ICP source are strongly affected by its electrical impedance and the electric/magnetic field distribution. The ICP source impedance is determined by the antenna impedance and the plasma one. It is preferred to keep the imaginary impedance between -100 ohm to 100 ohm, since it should be avoided the high voltage formation on the antenna and abrupt impedance variation during the thin film process. The plasma uniformity is affected by the electric and magnetic field which is formed by the antenna current and voltage. The influence of azimuthal symmetry are shown by the electromagnetic simulation and the measurement result of plasma density. The radial uniformity can be controlled by locating the concentric antennas which have different diameters. The power distribution ratio and its control method are presented in the case of parallel antenna connections.

• Journal of Internet of Things and Convergence
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• v.7 no.2
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• pp.7-12
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• 2021

Wisdom Contents are created with experiences and ideas of multiple authors, and consumed in Internet based Social Network Services that are not subjected to regional restrictions. Existing copyright management systems are designed for the protection of professional authors' rights, and effective in domestic area. On the contrary, the blockchain protocol is subjected to the service and the block is added by the consensus of participating nodes. If the data is stored to the blockchain, it cannot be modified or deleted. In this paper, we propose the blockchain based undeniable multi-signature scheme for the protection of multiple authorship on Wizdom Contents. The proposed scheme is consisted of co-authors' common public key generation, multi-signature generation and verification protocols. In the undeniable signature scheme, the signature cannot be verified without help of the signer. The proposed scheme is best suited to the contents purchase protocol. All co-authors cannot deny the fairness of the automated profit distribution through the verification of multiple authorship on Wizdom Contents.

• Journal of Digital Convergence
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• v.18 no.3
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• pp.259-266
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• 2020

This paper attempted to find the convergence factors related to the organizational citizenship behavior of hospital administration staff(HAS). The survey was conducted on 274 administrative staff at 22 hospitals in J regions randomly selected using self-administered questionnaires. The survey period took about a month from July 1 to July 31, 2019. The hierarchical multiple regression analysis shows the following results. The organizational citizenship behavior of respondents turned out to be significantly higher in following groups: The higher the procedure justice, sub-areas of organization justice, the higher the intragroup trust, and the higher the organizational commitment. Their explanatory power was 41.9%. The results of the study indicate that the efforts, to increase organization justice, intragroup trust and organizational commitment, are required to improve organizational citizenship behavior among HAS. The above results are expected to be utilized in human resource management and industrial health education of medical institutions that enhance organizational citizenship behavior of HAS. Later research requires the establishment of a structural equation model that affects organizational citizenship behavior of HAS.

• Journal of Science and Technology Studies
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• v.18 no.3
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• pp.153-216
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• 2018

The contemporary practices of Big-Data based automated decision making algorithms are widely deployed not just because we expect algorithmic decision making might distribute social resources in a more efficient way but also because we hope algorithms might make fairer decisions than the ones humans make with their prejudice, bias, and arbitrary judgment. However, there are increasingly more claims that algorithmic decision making does not do justice to those who are affected by the outcome. These unfair examples bring about new important questions such as how decision making was translated into processes and which factors should be considered to constitute to fair decision making. This paper attempts to delve into a bunch of research which addressed three areas of algorithmic application: criminal justice, law enforcement, and national security. By doing so, it will address some questions about whether artificial intelligence algorithm discriminates certain groups of humans and what are the criteria of a fair decision making process. Prior to the review, factors in each stage of data mining that could, either deliberately or unintentionally, lead to discriminatory results will be discussed. This paper will conclude with implications of this theoretical and practical analysis for the contemporary Korean society.

• Korean Journal of Optics and Photonics
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• v.35 no.4
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• pp.175-183
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• 2024

Research into optical signal processing using photonic integrated circuits (PICs) has been actively pursued in various fields, including optical communication, optical sensors, and quantum optics. Among the materials used in PIC fabrication, polymers have attracted significant interest due to their unique characteristics. To fabricate polymer-based PICs, establishing an accurate manufacturing process for the cross-sectional structure of an optical waveguide is crucial. For stable device performance and high yield in mass production, a process with high reproducibility and a wide tolerance for variation is necessary. This study proposes an efficient method for fabricating polymer optical-waveguide devices by introducing the atomic layer deposition (ALD) process. Compared to conventional photoresist or metal-film deposition methods, the ALD process enables more precise fabrication of the optical waveguide's core structure. Polyimide optical waveguides with a core size of 1.8 × 1.6 ㎛² are fabricated using the ALD process, and their propagation losses are measured. Additionally, a multimode interference (MMI) optical-waveguide power-splitter device is fabricated and characterized. Throughout the fabrication, no cracking issues are observed in the etching-mask layer, the vertical profiles of the waveguide patterns are excellent, and the propagation loss is below 1.5 dB/cm. These results confirm that the ALD process is a suitable method for the mass production of high-quality polymer photonic devices.

• Clean Technology
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• v.29 no.4
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• pp.255-261
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• 2023

Power semiconductors are semiconductors used for power conversion, transformation, distribution, and control. Recently, the global demand for high-voltage power semiconductors is increasing across various industrial fields, and optimization research on high-voltage IGBT components is urgently needed in these industries. For high-voltage IGBT development, setting the resistance value of the wafer and optimizing key unit processes are major variables in the electrical characteristics of the finished chip. Furthermore, the securing process and optimization of the technology to support high breakdown voltage is also important. Etching is a process of transferring the pattern of the mask circuit in the photolithography process to the wafer and removing unnecessary parts at the bottom of the photoresist film. Ion implantation is a process of injecting impurities along with thermal diffusion technology into the wafer substrate during the semiconductor manufacturing process. This process helps achieve a certain conductivity. In this study, dry etching and wet etching were controlled during field ring etching, which is an important process for forming a ring structure that supports the 3.3 kV breakdown voltage of IGBT, in order to analyze four conditions and form a stable body junction depth to secure the breakdown voltage. The field ring ion implantation process was optimized based on the TEG design by dividing it into four conditions. The wet etching 1-step method was advantageous in terms of process and work efficiency, and the ring pattern ion implantation conditions showed a doping concentration of 9.0E13 and an energy of 120 keV. The p-ion implantation conditions were optimized at a doping concentration of 6.5E13 and an energy of 80 keV, and the p+ ion implantation conditions were optimized at a doping concentration of 3.0E15 and an energy of 160 keV.