• Journal of Korean Society of Water Science and Technology
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• v.26 no.6
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• pp.61-72
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• 2018

In this study, applicability of the decentralized water supply system were investigated by the high flux evaluation using ceramic membrane with combined pretreatment process. A) filtration process increased the transmembrane pressure of 1.4 kPa and 89.5 kPa on 2 and $5m^3/m^2{\cdot}d$ of filtration flux, respectively, the physical backwashing recovery rate were less than 28.6%. The (B) Coag./Floc. - Sedi. combined process with 4 mg / L of A-PAC showed that the transmembrane pressure increased to within 6 kPa, the physical backwashing recovery rate was over 37.9 % higher than (A) Filtration process. (C) Coag./Floc. combined process showed an increase of transmembrane pressure compared with (B) Coag./Floc. - Sedi. combined process, physical backwashing recovery rate was over 84%. As a result of the membrane fouling analysis using the resistance in series model, the combined pretreatment process showed that the cake resistance (Rc) was more than 92% at membrane filtration flux of $2m^3/m^2{\cdot}d$. In the (C) Coag./Floc. combined process, cake resistance(Rc) was over 86% on high flux conditions. The coagulation floc contained in influent was removed by the membrane, and the cake layer formed with the removed floc was identified as reversible fouling resistance which could be recovered by physical backwashing. The decentralized water supply system, which has the limitation of site area and installation space, is considered to could be operation of high flux of ceramic membrane by applying (C) Coag./Floc. combined process without sedimentation process.

• Asia pacific journal of information systems
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• v.5 no.2
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• pp.177-197
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• 1995

In a study involving 52 large organizations in the savings institutions industry, the relationship between information systems technology (IST) structure and competitive strategy was investigated based on structural contingency theory. Structural contingency theory argues that organizational performance is contingent on the congruence between structure and contingent factors. Competitive strategy is considered to be the most important contingent factor among organizational context variables. Two dimensions of IST structure and three types of competitive strategy were employed to test a contingency model. It was found that enhanced congruence between IST structure and competitive strategy was associated with higher competitive advantage. The structural dimension significantly associated with the "defender" strategic stance was more centralized and more integrated application of IST, while the structural dimension significantly associated with "prospector" positioning was more decentralized and less integrated application of IST.

• Journal of the Korean Institute of Intelligent Systems
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• v.18 no.4
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• pp.537-542
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• 2008

Cricket is an excellent indoor location system and it can successfully solve many critical problems such as user privacy, decentralized administration. But in some practical applications, Cricket sometimes didn't provide location with enough accuracy, and was unable to determine when it was giving inaccurate information. For getting high-accuracy tracking performance from location data contaminated with noise, some types of filters are required. Kalman Filter is an efficient recursive filter that estimates the state of a dynamic system from a series of incomplete and noisy measurement. The filter is very powerful in the field of autonomous and assisted navigation. In this paper, we carry out comparative studies to validate the performance of the application of Kalman Filter to Cricket based localization system.

• Proceedings of the Korea Information Processing Society Conference
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• 2023.11a
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• pp.260-263
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• 2023

Considering the growth of blockchain technology, the research aims to transform the efficiency of recommending optimal coffee suppliers within the complex supply chain network. This transformation relies on the extraction of vital transactional data and insights from stakeholders, facilitated by the dynamic interaction between the application interface (e.g., Rest API) and the blockchain network. These extracted data are then subjected to advanced data processing techniques and harnessed through machine learning methodologies to establish a robust recommendation system. This innovative approach seeks to empower users with informed decision-making abilities, thereby enhancing operational efficiency in identifying the most suitable coffee supplier for each customer. Furthermore, the research employs data visualization techniques to illustrate intricate clustering patterns generated by the K-Means algorithm, providing a visual dimension to the study's evaluation.

• International Journal of Computer Science & Network Security
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• v.21 no.12
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• pp.235-247
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• 2021

Today, the cloud computing has become a major demand of many organizations. The major reason behind this expansion is due to its cloud's sharing infrastructure with higher computing efficiency, lower cost and higher fle3xibility. But, still the security is being a hurdle that blocks the success of the cloud computing platform. Therefore, a novel Multi-tenant Decentralized Information Flow Control (MT-DIFC) model is introduced in this research work. The proposed system will encapsulate four types of entities: (1) The central authority (CA), (2) The encryption proxy (EP), (3) Cloud server CS and (4) Multi-tenant Cloud virtual machines. Our contribution resides within the encryption proxy (EP). Initially, the trust level of all the users within each of the cloud is computed using the proposed two-stage trust computational model, wherein the user is categorized bas primary and secondary users. The primary and secondary users vary based on the application and data owner's preference. Based on the computed trust level, the access privilege is provided to the cloud users. In EP, the cipher text information flow security strategy is implemented using the blowfish encryption model. For the data encryption as well as decryption, the key generation is the crucial as well as the challenging part. In this research work, a new optimal key generation is carried out within the blowfish encryption Algorithm. In the blowfish encryption Algorithm, both the data encryption as well as decryption is accomplishment using the newly proposed optimal key. The proposed optimal key has been selected using a new Self Improved Cat and Mouse Based Optimizer (SI-CMBO), which has been an advanced version of the standard Cat and Mouse Based Optimizer. The proposed model is validated in terms of encryption time, decryption time, KPA attacks as well.

• Journal of the Korea Society of Computer and Information
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• v.26 no.6
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• pp.97-105
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• 2021

In this paper, we propose BCON, a service that allows individuals to store personal contents safely, and reliably guarantee their ownership of contents, certifying their identities with DIDs(Decentralized identifiers). DID technology, which supports decentralized identification service based on a blockchain that cannot forgery or alter data, allows users to selectively provide their information, controlling personal information and reinforcing their sovereignty over their identity. BCON stores information about the content specified by a user on the blockchain and Authenticates the user's identity based on DID technology. It also provides functions for the user to safely upload and download the user's content to a distributed database. BCON consists of the content service verifier, the content storage service, the content management contract, and the user application, administrating rhe DID registry for Authority management.

• The Journal of Korea Robotics Society
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• v.13 no.3
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• pp.157-163
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• 2018

This paper deals with the development and application of control algorithms for series elastic relief robots for rescue operations in harsh environment like disasters or battlefield. The joint controller applied in this paper has a cascade structure combining inner loop for torque control and outer loop for position control. The torque loop contains feedforward and feedback controller and disturbance observer for independent, decentralized joint control. The effect of the elastic component and motor dynamics are treated as the nonlinear disturbance and compensated with the disturbance observer of torque controller. For the collision detection, Band Designed Disturbance Observer is configured to recognize/respond to external disturbance robustly in the continuously changing environment. The controller is applied to a 7-dof series elastic manipulator to evaluate the torque tracking and collision detection/response performance.

• 유체기계공업학회:학술대회논문집
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• 2006.08a
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• pp.313-316
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• 2006

As Decentralized Generation(DG) becomes more reliable and economically feasible, it is expected that a higher application of DG units would be interconnected to the existing grids. This new market penetration of DG technologies is linked to a large number of factors like technologies costs and performances, interconnection issues, safety, market regulations, environmental issues or grid connection constrains. Korea Electric Power Corporation (KEPCO) has researched performance characteristics of the 60k W class 1) basic start-up & shutdown operation analysis 2) interconnection test 3) MGT -absorption chiller-heater system in the local condition. Variations of heat recovery from exhaust gas has measured according to micro gas turbine output of 15, 30, 45, 60kW. From those results, the performance of the MGT-absorption chiller/heater system has been evaluated. The suggested strategy and experience for the evaluation of the distributed generation will be used for the introduction of other distributed generation technologies into the grid in the future.

• Transactions on Control, Automation and Systems Engineering
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• v.3 no.4
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• pp.250-256
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• 2001

This paper deals with a design problem of a decentralized controller with a strongly connected two-input two-output multivariable system. To this end, we present a classical design approach which consists of two main steps: one is to decompose the multivariable plant into two single-input single-output systems by means of the Individual Channel Design (ICD) concept, the other is to design controller of each channel by the Coefficient Diagram Method (CDM) so that it satisfies, especially, time domain specifications such as settling time, overshoot etc.. A design procedure was proposed and then was applied to a 2$\times$2 hot rolling mill plant. Simulation results showed that the proposed method has excellent control performances.

• 제어로봇시스템학회:학술대회논문집
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• 1999.10a
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• pp.230-233
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• 1999

This paper is concerned with the design method of a de-centralized linear control system and its application to vibration control of multi degree of freedom structures. The method is based on the partial model matching on frequency domain by minimizing the relative model error functions between the diagonal elements of the open loop transfer function matrix of the control system and these of the reference model. The method is examined and evaluated by both simulation and experiment of a multi degree of freedom structure(MDFS).