• Journal of Advanced Marine Engineering and Technology
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• v.40 no.4
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• pp.282-287
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• 2016

Recently in order to protect the ocean environment and to reduce energy consumption, shipbuilders have been developing highly economized ships. This research analyzed the possibility of adopting the onshore absorption refrigerator to offshore ships having a cooling system with refrigerant by using the waiste heat of the engine jacket cooling water instead of compression refrigerators. The results showed that R236fa could be a suitable medium for absorbing the heat of the absorber and condenser in an absorption refrigerator. The cooling system using R236fa achieved a high COP of 0.798, which is 15% and 5% higher than an air cooling system with a cooling tower and a water cooling system with a heat exchanger, respectively. The cooling system with R236fa achieved high efficiency with a 25% reduction in flow rate of LiBr solution and only 15.7% flow rate of cooling medium as compared to the water cooling system. The heating of sea water by the engine jacket water flowing out from the generator can prevent the crystallization of LiBr solution due to the low temperature of sea water.

• Journal of the Korea Concrete Institute
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• v.29 no.4
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• pp.379-387
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• 2017

The objective of this study is to develop sustainable PVA fiber-reinforced cementitious composites (FRCCs) that could exhibit comparable strength level to normal PVA FRCCs with no recycled materials. To evaluate mechanical properties of the FRCCs, compressive, flexural and direct tensile tests were conducted. In addition to the test, to calculate amount of carbon dioxide ($CO_2$) emission at the stage of manufacturing the FRCCs, life cycle inventory data base (LCI DB) were referenced from domestic and Japan. From the test results, the mechanical properties such as compressive, flexural and direct tensile strengths were decreased as the replacement ratio of recycled materials increased. And it was determined that the amount of $CO_2$ emission was reduced for the specimens with higher water-binder ratio (W/B) and replacement ratios. It was also found that binder intensity ($B_i$) value was higher as replacement ratio of fly ash (FA) increased. This result means that larger amount of FA is need to deliver one unit of a given performance indicator (1 MPa of strength) of FRCCs compared to that of ordinary portland cement (OPC). As a result, it could be concluded that FRCCs with W/B 45% replaced by FA 25% and recycled sand (RS) 25% is desirable for both target performance and $CO_2$ emission.

• Development and Reproduction
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• v.7 no.1
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• pp.15-22
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• 2003

The Fas antigen (Fas) as a cell-surface receptor protein which mediates apoptosis-inducing signals plays an important role in the immune system. Expression of Fas mRNA is detected not only in lymphoid organs but also in the nonlymphoid organs. In the ovary, most of the follicles is known to undergo atreisa through apoptosis. However, the exact mechanism of atresia was not elucidated yet. Therefore, the purposes of the present study were to investigate the expression of Fas and Fas ligand in mouse ovary and to clarify the relationship between expression of Fas and Fas ligand and atresia of follicle. The result of RT-PCR demonstrated that Fas and Fas ligand mRNA was expressed in ovary, especially granulosa cells and oocytes. The immunohistochemistry showed that the granulosa cells and oocytes in growing follicles were stained for Fas and Fas ligand, but primordial follicles were not. Furthermore, Fas and Fas ligand were intensively stained in the atretic follicles As results of TUNEL staining to detect apoptotic cells in the ovaries, the number of TUNEL-positive (apoptotic) granulosa cells and oocytes increased in the atretic follicles compared to the healthy normal follicles. These results demonstrate that there is the positive relationship between expression of Fas and Fas ligand in granulosa cells and oocyies and apoptosis of them leading to atresia of follicles. It suggests that expression of Fas and Fas ligand could be associated with atresia of follicles in mouse ovary.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.17 no.7
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• pp.1951-1975
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• 2023

Recent advances in Cognitive Radio Networks (CRN) have elevated them to the status of a critical instrument for overcoming spectrum limits and achieving severe future wireless communication requirements. Collaborative spectrum sensing is presented for efficient channel selection because spectrum sensing is an essential part of CRNs. This study presents an innovative cooperative spectrum sensing (CSS) model that is built on the Firefly Algorithm (FA), as well as machine learning artificial neural networks (ANN). This system makes use of user grouping strategies to improve detection performance dramatically while lowering collaboration costs. Cooperative sensing wasn't used until after cognitive radio users had been correctly identified using energy data samples and an ANN model. Cooperative sensing strategies produce a user base that is either secure, requires less effort, or is faultless. The suggested method's purpose is to choose the best transmission channel. Clustering is utilized by the suggested ANN-FA model to reduce spectrum sensing inaccuracy. The transmission channel that has the highest weight is chosen by employing the method that has been provided for computing channel weight. The proposed ANN-FA model computes channel weight based on three sets of input parameters: PU utilization, CR count, and channel capacity. Using an improved evolutionary algorithm, the key principles of the ANN-FA scheme are optimized to boost the overall efficiency of the CRN channel selection technique. This study proposes the Artificial Neural Network with Firefly Algorithm (ANN-FA) for cognitive radio networks to overcome the obstacles. This proposed work focuses primarily on sensing the optimal secondary user channel and reducing the spectrum handoff delay in wireless networks. Several benchmark functions are utilized We analyze the efficacy of this innovative strategy by evaluating its performance. The performance of ANN-FA is 22.72 percent more robust and effective than that of the other metaheuristic algorithm, according to experimental findings. The proposed ANN-FA model is simulated using the NS2 simulator, The results are evaluated in terms of average interference ratio, spectrum opportunity utilization, three metrics are measured: packet delivery ratio (PDR), end-to-end delay, and end-to-average throughput for a variety of different CRs found in the network.

• Convergence Security Journal
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• v.7 no.4
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• pp.1-8
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• 2007

Currently, the needs of open standard and integrated network, and also applications of Ethernet network based system are increasing. By applying and expanding TCP/IP based network technology from high to low control level, factory automation application has been implemented, and thus integrated factory automation system has been accomplished, which is directly interoperable between high level management program and DB system. This paper proposes a communication control device which is based on Ethernet/IP standard system for factory automation. The proposed system is workable in the environment of a network system, which is based on CIP standard interface technology. The proposed system can also contribute to improve data communication characteristics.

• Journal of Electrical Engineering and Technology
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• v.13 no.2
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• pp.580-590
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• 2018

Active distribution system (ADS) considering distributed generation (DG) and electric vehicle (EV) is an effective way to cut carbon emission and improve system benefits. ADS is an evolving, complex and uncertain system, thus comprehensive model and effective optimization algorithms are needed. Battery swapping station (BSS) for EV service is an essential type of flexible load (FL). This paper establishes ADS planning model considering BSS firstly for the minimization of total cost including feeder investment, operation and maintenance, net loss and carbon tax. Meanwhile, immune binary firefly algorithm (IBFA) is proposed to optimize ADS planning. Firefly algorithm (FA) is a novel intelligent algorithm with simple structure and good convergence. By involving biological immune system into FA, IBFA adjusts antibody population scale to increase diversity and global search capability. To validate proposed algorithm, IBFA is compared with particle swarm optimization (PSO) algorithm on IEEE 39-bus system. The results prove that IBFA performs better than PSO in global search and convergence in ADS planning.

• Journal of Power System Engineering
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• v.21 no.1
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• pp.24-29
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• 2017

Studies in liquid-vapor ejector, which performs a great efficiency in refrigeration cycle is highly concerned. This paper is based on basic refrigeration cycle and three ejector refrigeration cycles and the comparison and contrasts about when 6 different refrigerants are applied to such refrigeration cycles. All cycles had a percentage increase of COP from 4 to 74% when ejector was applied, and the source of increasement was the decrease of total work done due to ejector's pressure recovery function. When R-245fa is applied to cycle (d), results showed that COP was the most superior in such cycle, R-245fa showed high volume entrainment ratio in all cycles. Future studies in refrigeration cycles will require more knowledge and experiments on ejector's appliance to refrigeration cycles and the actuation of such functions.

• Journal of the Korean Society of Safety
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• v.9 no.4
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• pp.49-57
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• 1994

In this paper, a speed controller using a controller is implemented and applied to a DC motor for FA ( Factory Automation ). The objective of this paper treats the analytical and experimental studies on the improvement of control circuit and control method using a SCR-LEONARD circuit for the speed control of DC motor. This system is concerned with stabilization of single input or single output systems, so the plant (SCR-LEONARD+DC motor) is simplified to the first order system. The parameters for the PID controller are obtained by the transient-response tunning method, and this control scheme has a backward-shift operator. The control algorithms (Chopper＋transient response tunning) is used to check the performance of PID Controller through Computer simulations and experiments. The good experiment results show that the direct control of the DC motor applied to industrial field such oi factory automation.

• Proceedings of the KIPE Conference
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• 2004.07b
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• pp.524-527
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• 2004

When the electric tractions are stopped or driven through the falling slope way, it occured to surplus energy in the DC power line. At present, these energy are exhausted by breaking-system. The converter is not only capable of feeding energy back into the AC source during excessive regeneration. It is issued for this surplus energy regenerating system. These systems are faced with high voltage and high power for railway DC power regeneration. This paper proposed a parallel PWM converter how to solve these problem.

• IE interfaces
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• v.8 no.3
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• pp.61-73
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• 1995

As the level of maunfacturing system automation increases, the issues of modeling and simulation of AMS(Automated Manufacturing System) are becoming more important. Proposed in this paper is the JR-Net(Job Resource relation-Net) modeling framework which naturally mimics the process of designing an AMS by FA(Factory Automation) engineers. Its main purpose is to provide a modeling tool which facilitate modeling work of AMS for FA engineers unfamiliar with simulation modeling. The proposed modeling scheme is based on the extensive observation that typical AMSs are built from the set of 'standard' components(or catalog items). As an application of the proposed model, two real examples of FMS('G7'FMS model plant, RPI FMS) are modeled by JR-Net, and in case of FMS model plant, a simulation program development procedure using JR-Net modeling results is explained. Finally, simulation result of FMS model plant is analyzed.