• Journal of Korean Society of Industrial and Systems Engineering
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• v.25 no.5
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• pp.9-14
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• 2002

A capital investment problem is essentially one of determining whether the anticipated cash inflows from a proposed project are sufficiently attractive to invest funds in the project. The net present value(NPV) criterion and internal rate of return(IRR) criterion are widely used as means of making investment decisions. A positive NPV means the equivalent worth of the inflows is greater than the equivalent worth of outflows, so, the project makes profit. Business people are familiar with rates of return because they all borrow money to finance ventures, even if the money they borrow is their own. Thus they are apt to use the IRR in preference to the NPV. The IRR can be defined as the discount rate that causes the net present value of a cash flow to equal zero. Why the project are accepted if the project's IRR is greater than the investor's minimum attractive rate of return\ulcorner Against the NPV, the definition cannot distinctly explain the concept of the IRR as decision criterion. We present a new definition of the IRR as the ratio of profit on the invested capital.

• International Journal of Fluid Machinery and Systems
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• v.3 no.4
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• pp.379-385
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• 2010

We developed a high-efficiency, wide-operating-range centrifugal blower stage to meet the demand for reduced total energy-consumption in sewage treatment plants. We improved the efficiency of the two-dimensional impeller using a shape optimization tool and one-dimensional performance prediction tool. A limit of the throat deceleration ratio was set to maintain the stall-margin of the impeller. The low solidity vaned diffuser and return channel were designed using a sensitivity analysis with orthogonal arrays and three-dimensional steady flow simulations. The low solidity diffuser was designed in order to improve the performance in the low-flow-rate region. The return channel was designed so that the total pressure loss in the return channel was minimized. Model tests of both the conventional and optimized blower stages were carried out, and the efficiency and operating range of both stages were compared. The optimized blower stage improved in stage efficiency by 3% and in operating range by 5% compared with the conventional blower stage.

• Progress in Superconductivity and Cryogenics
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• v.26 no.1
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• pp.25-30
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• 2024

High-temperature superconducting rotors offer advantages in terms of output-to-weight ratio and efficiency compared to conventional phase conduction motors or generators. The rotor can be cooled by conduction cooling, which attaches a cryocooler, and by refrigerant circulation, which uses circulating liquid or gas neon, helium and hydrogen. Recent work has focused on environmental issues and on high-temperature superconducting motors cooled with liquid hydrogen that can be combined with fuel cells. However, to ensure smooth supply and return of the cryogenic cooling fluid, a cryogenic rotational coupling between the rotating and stationary parts is necessary. Additionally, the development of a sealing structure to minimize fluid leakage applicable to the coupling is essential. This study describes the design and performance evaluation of a non-contact sealing method, specifically a labyrinth seal, which avoids power loss and heat load caused by friction in contact sealing structures. The seal design incorporates a spiral flow path to reduce leakage using centrifugal force, and computational fluid dynamics (CFD) simulations were conducted to analyze the flow path and rotational speed. A performance evaluation device was configured and employed to evaluate the designed seal. The results of this study will be used to develop a cryogenic rotational coupling with supply and return flow paths for cryogenic applications.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.6 no.9
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• pp.27-33
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• 1983

This Paper represents time-dependent stochastic variations of common discounted cash flow formulae with explicit consideration given to inflation. The cash flow, the ratio of discounting or compounding, and the rate of inflation are allowed to vary with time in a random fashion in equations for the compound amount of a single payment, present worth of a single payment, amount of an annuity, periodic deposits to accumulate a future amounts, present worth of an annuity and capital recovery And all formulae are derived for the case of discrete random variations.

• Health Policy and Management
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• v.15 no.4
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• pp.81-109
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• 2005

According to many recent studies suggesting that cash flow analysis method tends to be more effective than traditional financial index analysis method to predict corporate bankruptcy, this study applies the cash flow analysis method to hospital business to identify the significant variables which can distinguish between superior hospitals and bankruptcy hospitals. The author analyzed recent 3 years, i.e. from the year of 2000 to the year of 2002, financial statements of 31 bankrupt hospitals In 2003, and the same number of superior hospitals through using Multiple Discriminant Analysis and Logit Analysis. The results are belows; First, the study releases that Logit Analysis is more likely to be effective than Multiple Discriminant Analysis. Second, this research also shows that traditional financial index analysis method is more superior compare to cash flow analysis method for hospital bankruptcy predict model. Finally, this study suggest that the significant variables, which can distinguish superior hospitals from bankrupt hospitals, are Operating/Current Liabilities$(Y_2)$, CFO/Equity$(Y_5)$ for cash flow analysis method and Net Worth to Total Assets Ratio$(X_1)$, Quick Ratio $(X_3)$, Return on Assets$(X_6)$, Growth Rate of Patient Revenues$(X_{16})$ for traditional financial index analysis method.

• Water for future
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• v.29 no.3
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• pp.207-216
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• 1996

The subject research attempts to evaluate the variations of total runoff volume, peak flow, and travel time depending on the urbanhization, return periods and rainfall patterns under the situations that the preparation of a large residential site at the lowland areas of the downstream of Dongsu stream in Bupyung-Gu, Incheon city is progressed and the area will be eventually fully developed. The ILLUDAS model was used for the runoff analyses based on 3 differend steps of urbanization and 4 different types of Huff's quantile according to rainfall patterns is Huff's 4 quantile, Huff's 2 quantile, Huff's 3 quantile and Huff's 1 quantile. Under the 80 and 90 % of urbanization to the 70% of urbanization, the mean increasing ratio of total runoff volume for each case is 3.5 and 5.5 %, that of peak flow is 4.2 and 8.8%, and the mean decreasing ratio of travel time is 4.4 and 10.1%, respectively. The mean increasing ratio of total runoff volume according to the return periods is 3.0 and 5.4%, that of peak flow is 3.9 and 8.0% under the same conditions of urbanization.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.15 no.4
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• pp.2526-2531
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• 2014

This paper has analyzed the effects of CEO turnover and other fundamental variables on stock returns. Therefore, the major purpose of this study is to analyze CEO turnover having a systematical effect on the stock return. The paper uses panel data analysis. We find that the results of regressions say that CEO turnover, book-to-market ratio, earning-to-price ratio, cash flow-to-price ratio, and firm size can explain the differences in average returns across stocks.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.13 no.3
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• pp.1035-1041
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• 2012

This paper examines the effects of fundamental variables on stock returns. Therefore, the major purpose of this study is to identify fundamental variables having a systematical effect on the stock return. The paper uses panel data analysis. We find that the results of regressions say that firm size, book-to-market ratio(B/M), earning-to-price ratio(E/P), cash flow-to-price ratio(C/P) can explain the differences in average returns across stocks.

• Proceedings of the KSME Conference
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• 2008.11b
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• pp.2248-2253
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• 2008

A numerical study on oscillatory thermocapillary flow in half-zone has performed to understand the effect of axial rotation. 2d unsteady code is developed to observe the onset of oscillation. 2cs Silicone oil with Prandtl number of 26.5 is used as a working fluid. The critical temperature difference at onset of oscillation is investigated under the different aspect ratios and rotation modes. It is shown that the onset of oscillation is delayed when aspect ratio reduces and rotating speed increases. The oscillatory flow is strongly reduced under top rotation and co-rotation modes, while it is augmented under bottom rotation and counter-rotation modes. It is thought that interaction between return flow and bottom wall is important to explain the oscillatory flow.

• Journal of the Korean Society for Precision Engineering
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• v.14 no.8
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• pp.146-154
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• 1997

Solenoid-folw control type ABS is used with a 'dump and reapply' pressure control arrangement instead of using 2/2 (normal open/close) solenoid valves in convensional systems(sol. -sol. control type), a flow control valve is used which replaces the (no) inlet valve. The flow control valve controls fluid flow providing a nearly constant reapply rate( .theta. ) after the dump plase of ABS operation. In this study, to investigate a characteristics of brake pressure by PWM control, test rig was consisted of ABS hydraulic modulator, digital controller, pneumatic power supply and brake master cylinder. For comparison with experi- mental results, system modelling and computer simulation were performed. As a result, experiment results showed fairly agreement with the simulation. Also, it is shown that the pressure gradient (tan .theta. ) is affected by pressure, frequency, duty ratio and expressed with an exponential funtion.