• The Journal of the Korea Contents Association
• /
• v.5 no.1
• /
• pp.147-155
• /
• 2005

In this paper, communication channels for the transmission of multimedia packets are modeled and evaluated. The multimedia packet traffic characterized by on-off and MMPP process for voice and data, respectively, dynamic channel allocation, queueing of data packets due to unavailability of channels and dropping of queued data packets over timeout, and guard channel for voice packets are modeled. The performance indices adopted in the evaluation of SRN model includes blocking and dropping probabilities. The SRN uses rewards concepts instead of the complicate numerical analysis required for the Markov chain. It is shown that our SRN modeling techniques provide an easier way to carry out performance analysis.

• Journal of the Korean Society of Systems Engineering
• /
• v.12 no.2
• /
• pp.91-99
• /
• 2016

The safety of nuclear power plants has received much attention; this safety largely depends on the continuous availability of electrical energy source during all modes of nuclear power plant operation. A station blackout (SBO) describes the loss of the off-site electric power, the failure of the emergency diesel generators, and the unavailability of the alternate AC (AAC) power. Consequently, all systems that are AC powered such as the safety injection, shutdown cooling, component cooling water, and essential service water systems are unavailable. The aim of this study is to investigate the deficiencies of the existing alternatives for coping with an extended SBO for APR1400 design. The method is analyzing the existing deficiencies and proposing an optimal solution for the NPP design during the extended SBO. This study, established a new passive system, called passive decay heat removal system (PDHRS), using systems engineering approach.

• 한국태양에너지학회:학술대회논문집
• /
• 2008.04a
• /
• pp.61-67
• /
• 2008

In this paper proposed the solar tracking system to use a fuzzy based on PC in order to increase an output of the PV array. The solar tracking system operated two DC motors driving by signal of photo sensor. The control of dual axes is not an easy task due to nonlinear dynamics and unavailability of the parameters. Recently, artificial intelligent control of the fuzzy control, neural-network and genetic algorithm etc. have been studied. The fuzzy control made a nonlinear dynamics to well perform and had a robust and highly efficient characteristic about a parameter variable as well as a nonlinear characteristic. Hence the fuzzy control was used to perform the tracking system after comparing with error values of setting-up. nonlinear altitude and azimuth. In this paper designed a fuzzy controller for improving output of PV array and evaluated comparison with efficient of conventional PI controller. The data which were obtained by experiment were able to show a validity of the proposed controller.

• Nuclear Engineering and Technology
• /
• v.52 no.4
• /
• pp.764-775
• /
• 2020

Periodic safety reviews (PSRs) are conducted on operating nuclear power plants (NPPs) and have been mandated also for research reactors in Korea, in response to the Fukushima accident. One safety review tool, the probabilistic safety assessment (PSA), aims to identify weaknesses in the design and operation of the research reactor, and to evaluate and compare possible safety improvements. However, the PSA for research reactors is difficult due to scarce data availability. An important element in the analysis of research reactors is the reactor protection system (RPS), with its functionality and importance. In this view, we consider that of the AGN-201K, a zero-power reactor without forced decay heat removal systems, to demonstrate a risk-informed safety improvement study. By incorporating risk- and safety-significance importance measures, and sensitivity and uncertainty analyses, the proposed method identifies critical components in the RPS reliability model, systematically proposes potential safety improvements and ranks them to assist in the decision-making process.

• Journal of Electrochemical Science and Technology
• /
• v.11 no.3
• /
• pp.220-237
• /
• 2020

Modern electrochemical energy devices involve generation and reduction of fuel gases through electrochemical reactions of water splitting, alcohol oxidation, oxygen reduction, etc. Initially, these processes were executed in the presence of noble metal-based catalyst that showed low overpotential and high current density. However, its high cost, unavailability, corrosion and related toxicity limited its application. The search for alternative with high stability, durability, and efficiency led scientists towards carbon nanoparticles supported catalysts which has high surface area, good electrical conductivity, tunable morphology, low cost, ease of synthesis and stability. Carbon nanoparticles are classified into two groups based on morphology, one and zero dimensional particles. Carbon nanoparticles at zero dimension, denoted as carbon dots, are less used carbon support compared to other forms. However, recently carbon dots with improved electronic properties have become popular as catalyst as well as catalyst support. This review focused on the recent advances in electrocatalytic activities of carbon dots. The mechanisms of common electrocatalytic reactions and the role of the catalysts are also discussed. The review also proposed future developments and other research directions to overcome current limitations.

• Journal of the Korea Institute of Military Science and Technology
• /
• v.17 no.3
• /
• pp.318-326
• /
• 2014

The Shipyard Test of Naval Combat System depends on external factors, such as weather conditions and availability of its sensor-weapon, due to the need of on-board sensor-weapon during the test. This paper suggests the Supportive Equipment using virtual simulator for Shipward Test, in case of the unavailability of the on-board sensor-weapon or the test support force(aircraft, surface ship etc.), to pre-check the functions of the combat system as well as to prepare the Shipyard Test. To mock the real sensor-weapon functions as similar as possible, the Supportive Equipment for Shipyard Test was verified by the Verification and Validation process, which is usually performed while developing models in the Modeling & Simulation field.

• Structural Engineering and Mechanics
• /
• v.46 no.5
• /
• pp.695-711
• /
• 2013

It is reasonable to assume that reinforced concrete (RC) structures enter the nonlinear range of response during a severe ground motion. Numerical analysis to predict the behaviour therefore must allow for the presence of nonlinear deformations if an accurate estimate of seismic response is aimed. Among the factors contributing to inelastic deformations, the influence of the degradation of the bond slip phenomenon is important. Any rebar slip generates an additional rotation at the end regions of structural members which are not accounted for in a conventional analysis. Although these deformations could affect the seismic response of RC structures considerably, they are often neglected due to the unavailability of suitable models. In this paper, the seismic response of two types of RC structures, designed according to the Iranian concrete code (ABA) and the Iranian seismic code (2800), are evaluated using nonlinear dynamic and static analyses. The investigation is performed using nonlinear dynamic and static pushover analysis considering the deformations due to anchorage slip. The nonlinear analysis results confirm that bond slip significantly influences the seismic behavior of RC structure leading to an increase of lateral deformations by up to 30% depending on the height of building. The outcomes also identify important parameters affecting the extent of this influence.

• The Korean Journal of Food & Health Convergence
• /
• v.6 no.1
• /
• pp.1-8
• /
• 2020

The foremost problem in the agricultural industry in Ukraine is the issue of improving its energy resources efficiency. The existence of this problem is related to the substantial technological inferiority of the industry to those present in the developed countries, especially in terms of creation of no-waste production technologies of agricultural products. The direct effect on the solving of this issue has the necessity to ensure minimal energy costs during treatment of plant objects. This article presents the research results on the effect of electromagnetic energy on activation of plants development. It was found that each such object has its own individual energy resource and that forceful increase of the latter has specific maximum values and gives rise to the plant development process. At the same time, the implementation of the research results is hindered by some factors, among the most major of which are the following: lack of reliable and complete data on the bioenergy resources of plants, its "natural" chart; unavailability of research on the energy sources interaction processes and its effect on the physiological potential of biological objects, at least at the level of low series, absence of the appropriate electrotechnical equipment, including electromagnetic energy sources.

• Nuclear Engineering and Technology
• /
• v.15 no.1
• /
• pp.57-69
• /
• 1983

The LWR fuel performance analysis computer code, FRAPCON-1, are evaluated to investigate the performance of CANDU fuel elements loaded in Wolsung-1 reactor. The FRAPCON-1 models of neutron flux depression in fuel and of fuel-to-cladding heat transfer are modified, and the validity of fission gas release model for CANDU fuel is evaluated. And the heavy water properties are provided in calculating the heat transfer coefficient between cladding and coolant. By using the modified code, FRAPCON-1-CSK, the sensitivity studies are carried out for Wolsung-1 fuel element design parameters. The performance analysis is also performed for Wolsung-l fuel elements. The calculated results are discussed in terms of. LWR fuel design criteria because of unavailability of CANDU fuel design criteria.

• The Journal of Asian Finance, Economics and Business
• /
• v.7 no.10
• /
• pp.323-328
• /
• 2020

This study aims to analyze the changes in purchasing decisions in conducting transactions using cash and digital payment systems. Cash payment systems are very different from digital payments because they no longer use banks as intermediaries for transactions. The scope of this study is to determine the differences that take place with purchasing decisions using digital payment systems with OVO Indonesia smart applications. By using the paired T-test sample test method and testing the regression class assumptions, it is expected we will document the comparison between cash and digital payment systems as regards changes in consumers' buying interest behavior towards goods. Data is obtained by purposive sampling using special characteristics for smart application users. The results show that digital payments are developing very quickly, but cash payments still dominate due to the unavailability of complete facilities and infrastructure to support digital payment systems other than in cities. This study illustrates that digital payments have not been able to completely change consumer buying behavior in large numbers, but the main finding in this study is an increase in the percentage of digital payment usage to the online market, due to the many conveniences provided in OVO smart applications.