• Proceedings of the Korean Nuclear Society Conference
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• 2003.10a
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• pp.219.2-219.2
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• 2003

• International Journal of Highway Engineering
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• v.12 no.2
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• pp.25-31
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• 2010

Road design guideline provides the directions on how to design a road alignment based on design speed, and this guideline has a design expectation in that design speed is supposed to be equal to the operating speed of drivers. Horizontal curve design is also based on design speed, and minimum radius is derived based on the drivers comfort while negotiating the curve. However, side friction reflecting drivers comfort is lower than a physical friction measured on wet road surface, therefore, it is reasonable to regard the criterion on minimum radius has a safety margin. Futhermore, the practical preference of choosing the larger radius than minimum leads to a noticeable gap between design speed and operating speed, so links to the violation of design expectation implicated in the guideline. In order to review this assumption, friction and operating speed at rural roads was measured and observed. As the results, a safety margin brought out by the gap between comfort-based friction and measured friction is qualitatively derived. Also, the gap between design speed and operating speed presumably caused by the safety margin and practical preference is analysed. By this, it is suggested that current design guideline should provides not only the minimum radius but also the management of road alignment design to minimize the gap between the design speed and operating speed.

• Journal of Preventive Medicine and Public Health
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• v.26 no.3 s.43
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• pp.442-456
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• 1993

Financial stability is the foremost prerequisite for the continuous growth and development of hospitals. The present study aimed at developing a deterministic model using the factors which affect the hospitals profitability and at discovering which factor affected the hospital profitability. The study conducted questionnaire surveys on all general hospitals, with the exception of special hospitals, with over eighty hospital beds. Of the 274 subject hospitals, 136 of them, consituting 49.6% of the whole, were used in the study. The results are as follows. 1. In the deterministic model, outpatient revenue was affected more by the number of physician visits than by outpatient service intensity. Inpatient revenue was found to be affected more by the number of discharged patients than by inpatient service intensity. However, the increase rate of the service intensity not only contributed in stepping up the operating margin by $4{\sim}8%$ in outpatient and $3{\sim}6%$ in inpatient, but it was statistically significant. 2. Among the factors which determined the operating cost within the deterministic model, the number of patients had a greater impact on the operating cost than the resource consumption per patient. 3. The resource consumption per patient were proved to have the greatest effect on the profitability within the probabilistic model. The management cost per adjusted patient, in particular, was proven to have a statistically significant effect on the profitability in all hospitals.

• Proceedings of the KSME Conference
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• 2007.05a
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• pp.1149-1154
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• 2007

Fluctuation of control rod was experienced when plant was operating in normal operation mode in WH type NPPs. In order to cope with increased control rod fluctuation, the lead-lag controller setpoint for rod control system was optimized and resulted in increasing the margin of operation and minimizing unnecessary control rod movement. By optimization of the time constant, the margin of operation was increased by $1.5^{\circ}F$ and the control rod movement was not occurred due to mitigation of temperature fluctuation in loop. According to the mitigation of time constant, the margin of operation was increased but safety margin can be affected badly, so that the influences to FSAR design reference was evaluated. As the result of this evaluation, it satisfied the design reference of the existing safety analysis and was applied to NPP after obtaining the approval.

• Journal of KSNVE
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• v.9 no.3
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• pp.570-576
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• 1999

This paper presents numerical and experimental results of modal parameter identification in a generator stator frame for 500 MW fossil power plants. A commercial finite element analysis S/W was employed for modal analysis. The generator is excited by alternating electromagnetic forces, mainly of 120 Hz in 60 Hz machines, due to magnetic field and electric current in windings. It is necessary to verify that the stator frame has adequate frequency margin from the excitation frequency to avoid possible resonance when operating. Thus, frequency margin required for the stator frame is established using the numerical and experimental results. The results show that the stator frame meets the frequency-margin requirements. Also, results of modal analysis for design modification in order to reduce weights of the stator frame without deteriorating vibration characteristics are presented.

• Proceedings of the Korea Institute of Applied Superconductivity and Cryogenics Conference
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• 2003.10a
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• pp.113-116
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• 2003

Confluence buffers and single flux quantum (SFQ) switches are essential components in constructing a high speed superconductive Arithmetic Logic Unit (ALU). In this work, we developed a SFQ confluence buffer and an SFQ switch. It is very important to optimize the circuit parameters of a confluence buffer and an SFQ switch to implement them into an ALU. The confluence buffer that we are currently using has a small bias margin of $\pm$11％. By optimizing it with a Josephson circuit simulator, we improved the design of confluence buffer. Our simulation study showed that we improved bias global margin of 10％ more than the existent confluence buffer. In simulations, the minimal bias margin was $\pm$33％. We also designed, fabricated, and tested an SFQ switch operating in a DC mode. The mask layout used to fabricate the SFQ switch was obtained after circuit optimization. The test results of our SFQ switch showed that it operated correctly and had a reasonably wide margin of $\pm$15％.

• 유체기계공업학회:학술대회논문집
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• 2003.12a
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• pp.88-91
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• 2003

A fuel spiking test was performed to measure the surge margin of gas turbine engines. The surge marin was mainly determined by the compressors and fuel spiking was used to change the operating point in the compressor characteristic map while speed remained constant. To access the surge margin region different spiking signals were applied by modulations of time(frequency) and fuel flow rate(amplitude). The test results showed good agreements with expected fuel spiking patterns and possibility of further studies.

• Journal of the Korea Society of Computer and Information
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• v.23 no.11
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• pp.67-74
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• 2018

The verification for the design limit margin of the power device for the information communication and surveillance systems using HALT(Highly Accelerated Life Test) reliability test is described. The HALT reliability test performs with a step stress method which change condition until the marginal step in a design and development phase. The HALT test methods are the low temperature(cold) step stress test, the high temperature(hot) step stress test, the thermal shock cyclic stess test, and the high temperature destruct limit(hot DL) step stress test. The power device is checked the operating performance during the test. In this paper, the HALT was performed to find out the design limit margin of the power device.

• Nuclear Engineering and Technology
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• v.26 no.2
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• pp.294-299
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• 1994

Margin benefits are quantatively assessed when a Digital Monitoring System(DMS) is assumed to be installed to an operating Westinghouse analog type plant. Applied plant and cycle is YongGwang Unit 1 Cycle 6. The referenced digital monitoring system is the COLSS (Core Operating Limit Supervisory System) of ABB-CE. Considered fuel design limits are DNBR and LDCA Fq. 2003-D Power distributions within the present CAOC (Constant Axial Offset Control) limits are calculated for the analysis. The most limiting DNB prevention event of CEA Withdrawal is analyzed with the ROPM (Required OverPower Margin) concept of ABB-CE. The result show that the DMS can bring around 7% more margins for both DNB and LOCA Fq standpoints of view. The DMS can also monitor the PCI (Pellet-Cladding Interaction) limits.

• The Journal of the Acoustical Society of Korea
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• v.4 no.1
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• pp.16-21
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• 1985

Both shifiting the input signal's frequencies by a fixed frequency and compressing the input signal's bandwidth have been known to be effective in improving the stability margin of public adress systems operating in reverberant spaces. This paper describes the effect of an alternative approach of improving the acoustic-feedback stability and yet maintaining speech inteligibility by bandwidth compression and expansion. Conditions are derived for this technizue to be realized and an experimental system has been made - up. A series of experiments has been performed in small spaces and the results have shown that more than 5dB improvement can be obtained in the stability margin.