• Proceedings of the KIEE Conference
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• 2002.11b
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• pp.151-153
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• 2002

Using UPFC(Unified Power Flow Controlled), it is possible to control three parameters(voltage, impedance, and phase angle). The UPFC can generate or absorb reactive power rapidly so as to enhance the transient and voltage stability and also influence the power flow. In this paper, the effects of application of the UPFC to the power system are analyzed from a viewpoint of improving the total transfer capability by enhancing voltage stability. The IPLAN, which is a high level language used with PSS/E program, is employed for evaluating the total transfer capability from a f-V curve.

• The Journal of the Korea Contents Association
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• v.17 no.6
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• pp.98-105
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• 2017

The medical institution considers liability management problems as a direct factor in managerial risks, such as bankruptcy. Cash Flow provides useful information to necessary funds and predicting bankruptcy. The study for 24 general hospitals and 23 hospitals, a regression analysis was performed to determine the impact of cash flows on the debt repayment capability, a multivariate discrimination analysis was conducted to find out how to manage cash flow for the risk posed by debt. The analysis results, For general hospitals, the level of debt repayment capability was done to net income, increase of payables from operating activities and decrease of patient receivables and inventories from operating activities. If there is no dept repayment capability, it is necessary to increase the net income, increase the expenses not involving cash outflows, decrease of patient receivables and increase of payables from operating activities. For hospitals, the level of debt repayment capability was done to net income, increase of expenses not involving cash outflows and payables from operating activities, decrease of income not involving cash inflows, decrease of patient receivables and inventories from operating activities. If there is no dept repayment capability, it is necessary to increase of payables from operating activities.

• Nuclear Engineering and Technology
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• v.50 no.4
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• pp.542-552
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• 2018

Operators face challenges to plan alternative countermeasures when no procedure exists to address the current plant state. A model-based approach is desired to aid operators in acquiring plant resources and deriving response plans. Multilevel flow modeling (MFM) is a functional modeling methodology that can represent intentional knowledge about systems, which is essential in response planning. This article investigates the capabilities of MFM to plan alternatives. It is concluded that MFM has a knowledge capability to represent alternative means that are designed for given ends and a reasoning capability to identify alternative functions that can causally influence the goal achievement. The second capability can be applied to find originally unassociated means to achieve a goal. This is vital in a situation where all designed means have failed. A technique of procedure synthesis can be used to express identified alternatives as a series of operations. A case of station blackout occurring at the boiling water reactor is described. An MFM model of a boiling water reactor is built according to the analysis of goals and functions. The accident situations are defined by the model, and several alternative countermeasures in terms of operating procedures are generated to achieve the goal of core cooling.

• Proceedings of the Technology Innovation Conference
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• 2000.06a
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• pp.47-64
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• 2000

This paper analyses characteristics of the numerical controller industry in market formation and the Flow of information between users and producers and the characteristic of knowledge base of the industry and discusses the difficulties derived, from the characteristics, in accumulation of technological capability In market formation betweenusers and producers, the multi-layered market is not favorable to domestic producers in that lower end market is not large enough to provide cardle market to them which produce inferior quality and lower price than importer products. The credibility of the permance of a product is difficult to prove until a critical mass of products are sold. Therefore gaining market share is deterred by unproven credibility of the performance of the product. The flow of information between users and producers is limited. The flow of information on users environment through mass market to producers is essential for improving credibility of a product. The nature of knowledge base is tacit and the means of knowledge transmission is limited. Technological licensing and reverse engineering, Which have been conventional industry. These characteristics provide conditions of vicious circle in accumulation of technological capability of the numerical controller industry. This paper argues that these characteristics of the industry challenges existing approach to R&D management and framework of science and technology policy.

• The KSFM Journal of Fluid Machinery
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• v.17 no.4
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• pp.5-10
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• 2014

It is possible for the nation's largest flowmeter calibration system in K-water to calibrate flow rate up to $2,700m^3/h$ and diameter 800mm. However, the calibration and measurement capability of K-water's system is not satisfied in comparison with other developed countries. In this study, we find the dominant factors related to the uncertainty of weight and time measurement for gravimetric flowmeter calibration system. As a results of improving the system, the combined standard uncertainty has been improved $1.099{\times}10^{-3}$ to $2.332{\times}10^{-4}$. So calibration and measurement capability got 0.08 percent of the relative expanded uncertainty for maximum flow rate using the coverage factor(k=2).

• International Journal of Naval Architecture and Ocean Engineering
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• v.6 no.2
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• pp.257-268
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• 2014

In this study, flow-driven rotor simulations with a given load are conducted to analyze the operational characteristics of a vertical-axis Darrieus turbine, specifically its self-starting capability and fluctuations in its torque as well as the RPM. These characteristics are typically observed in experiments, though they cannot be acquired in simulations with a given tip speed ratio (TSR). First, it is shown that a flow-driven rotor simulation with a two-dimensional (2D) turbine model obtains power coefficients with curves similar to those obtained in a simulation with a given TSR. 3D flow-driven rotor simulations with an optimal geometry then show that a helical-bladed turbine has the following prominent advantages over a straight-bladed turbine of the same size: an improvement of its self-starting capabilities and reduced fluctuations in its torque and RPM curves as well as an increase in its power coefficient from 33% to 42%. Therefore, it is clear that a flow-driven rotor simulation provides more information for the design of a Darrieus turbine than a simulation with a given TSR before experiments.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.59 no.6
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• pp.1017-1024
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• 2010

Under the Kyoto Protocol many countries have been requested to participate in emissions trading with the assigned $CO_2$ emissions. In this environment, it is inevitable to change the system and market operation in deregulated power systems, and then ensuring safety margin is becoming more important for balancing system security, economy and $CO_2$ emissions. Nowadays, available transfer capability (ATC) is a key index of the remaining capability of a transmission system for future transactions. This paper presents a novel approach to the ATC evaluation with $CO_2$ emissions using multi-objective particle swarm optimization (MOPSO) technique. This technique evolves a multi-objective version of PSO by proposing redefinition of global best and local best individuals in multi-objective optimization domain. The optimal power flow (OPF) method using MOPSO is suggested to solve multi-objective functions including fuel cost and $CO_2$ emissions simultaneously. To show its efficiency and effectiveness, the results of the proposed method is comprehensively realized by a comparison with the ATC which is not including $CO_2$ emissions for the IEEE 30-bus system, and is found to be quite promising.

• Transactions of the Korean hydrogen and new energy society
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• v.23 no.1
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• pp.19-25
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• 2012

The efficiency and life time of the Proton Exchange Membrane fuel cell (PEMFC) system is critically affected by incoming gas with humidity which should be maintained properly at normal operating conditions. Typically, incoming gas of automotive fuel cell is humidified by external humidifier but the characteristics of device is rarely reported. In this study, characteristics of water transfer in the membrane humidifiers have been experimentally investigated for flow rates of gas and for different flow arrangement under steady state condition. At first, capability of mass transfer through the membrane is examined at constant temperature. Then, the temperature distribution effect on the capability of mass transfer is tested over various inlet conditions. In summary, this research presents the mass transfer capability of hydrophilic membrane over various operating conditions.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.32 no.2
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• pp.117-124
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• 2008

Recent researches on nanofluids have mainly focused on the increase of thermal conductivity of nanofluids under static condition. The ultimate goal of using nanofluids, however, is to enhance the heat transfer performance under fluid flow. So it has been highly necessary to devise a simple and accurate measuring apparatus which effectively compares the heat transfer capability between the base and nanofluids. Though the convective heat transfer coefficient is not the complete index for the heat transfer capability, it might be one of useful indications of heat transfer enhancement. In this article, the working principles of experimental system for convective heat transfer coefficient around a heated fine wire in cross flow of nanofluids and its application example to three samples of nano lubrication oils are explained in detail.

• Proceedings of the IEEK Conference
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• 1998.10a
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• pp.261-264
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• 1998

Controlled transfer (CT) capability, a new ATM transfer capability (ATC) for high-speed data applications which using credit-based flow control, has recently been proposed and studied in ITU-T. In this paper, we review the existing dyanmic buffer allocation schemes and propose an improved scheme. Also, we compare the performances of the existing buffer allocation methods such as static allocation, flow controlled virtual channels (FCVC), and zero queueing flow control (ZQFC) with the proposed method through simulation. Simulation results show that the proposed scheme exhibits a better performance than the existing schemes in terms of throughput, fairness, queue length and link utilization.