• Journal of Advanced Marine Engineering and Technology
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• v.23 no.3
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• pp.300-310
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• 1999

A constant-volume combustion chamber is developed to measure the burnt gas temperature over the wide ranges of equivalence ratio from 1.5 to 2.7 and pressure from 0.1 to 2.7 and pressure from 0.1 to 6 MPa by two-color method. The combustion temperature is also calculated by the conventional two-region model. The premixed fuel rich propane-oxygen-inert gas mixtures under high pressures are simultaneously ignited by eight spark plugs located on the circumference of combustion chamber with 45 degree intervals. The eight converging flames compress the end gases to high pressures. The transmissiv-ity in the chamber center during the final stage of combustion at the highest pressure is measured by in situ laser extinction method. Comparisons are made with the combustion temperatures between two-color method and two-region model. It is found that the burnt gas temperature mea-sured by two-color method is higher than that calculated by two-region model because of being the negative temperature gradient on the calculation and the temperature distribution of light path-length on the measurement and the burnt gas temperature for the turbulent combustion is higher than that of the laminar combustion under the same conditions because the heat loss for turbulent combustion is lower due to the shorter combustion period.

• Journal of the Korean Institute of Intelligent Systems
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• v.20 no.1
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• pp.76-80
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• 2010

It is floating to security of information and the early assignment that it is important it processes and to transmit in inundations of information that I changed suddenly. I used the encryption/decryption process that applied simple substitution and mathematical calculation algorithm at theory and encryption transmission steps protective early information. Hardware and financial loss are using spurious random number to be satisfied with the random number anger that isn't real random number to size so much perfect information protection using One-time pad for applying this. I was transformed into serial test under a test to prove spurious random number anger, and it is into random number anger stronger, and the transformation serial test that proposes is proving it in algorithm speed and efficiency planes.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2011.04a
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• pp.638-643
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• 2011

The aluminum soundproofing panel used to the traffic noise reduction will judge with the material to improve because the CO2 emission is greater than other soundproofing panel such as plastic soundproofing panel. Also, if the air-passing soundproofing panel which can endure the fast wind velocity will be developed, it judged that it can reached to the target of low CO2 traffic technology development using the reduction of material cost and the lower consumption of steel. The objective of this study is to improve the soundproofing panel and to develop the air-passing soundproofing panel for the replacement of aluminum sound proofing panel which is more emit CO2 than other soundproofing panel. And, we tried to develop the reduction technology of CO2 emission through the development of air-passing soundproofing panel. At first, the flow and noise simulation were conducted for the purpose of the calculation of wind pressure on soundproofing wall and noise exposure level on receiver points according to the open ratio of air-passing soundproofing panel. And the 1st and 2nd mockup of air-passing soundproofing panel were made, and the design load test were conducted for these mockup.

• Proceedings of the KIEE Conference
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• 1990.07a
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• pp.154-157
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• 1990

This paper describes a new method of calculating expected energy generation and loss of load probability (L.O.L.P) for electric power system operation and expansion planning. The method represents an equivalent load duration curve (E.L.D.C) as a mixture of cumulants approximation (M.O.C.A), which is the general case of mixture of normals approximation (M.O.N.A). By regarding a load distribution as many normal distributions-rather than one normal distribution-and representing each of them in terms of Gram-Charller expansion, we could improve the accuracy of results. We developed an algorithm which automatically determines the number of distribution and demarcation points. In modelling of a supply system, we made subsets of generators according to the number of generator outage: since the calculation of each subset's moment needs to be processed rapidly, we futher developed specific recursive formulae. The method is applied to the test systems and the results are compared with those of cumulant, M.O.N.A and Booth-Baleriaux method. It is verified that the M.O.C.A method is faster and more accurate than any other methods.

• Journal of the Korean Society for Precision Engineering
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• v.26 no.12
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• pp.123-130
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• 2009

This study presents the application of a polymer behavior model that considers fluid mechanics and heat transfer effects in a deposition system. The analysis of the polymer fluid properties is very important in the fabrication of precise microstructures. This fluid behavior model involves the calculation of velocity distribution and mass flow rates that include the effect of heat loss in the needle. The effectiveness of the proposed method was demonstrated by comparing estimated mass fluid rates with experimental values. The mass fluid rates under various process conditions, such as pressure, temperature, and needle size, reflected the actual deposition state relatively well, and the assumption that molten polycaprolactone(PCL) is a non-Newtonian fluid was reasonable. The successful fabrication of three-dimensional microstructures demonstrated that the model is valid for predicting the polymer behavior characteristics in the microstructure fabrication process. The results of this study can be used to investigate the effect of various parameters on fabricated structures before turning to experimental approaches.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.47 no.12
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• pp.848-855
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• 2019

Eco-friendly gas turbine combustors are getting attention due to emission regulations. Swirler is important design factor for flame stability and flashback inside the combustor. Design methods of the axial swirler and the radial swirler were discussed and the suitability of the swirl number calculation considering the geometric design variables and the flow loss was examined in the radial swirl for gas turbine combustor. The swirl number of flow was calculated by computational fluid dynamics and compared with swirl number according to each design method.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.21 no.3
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• pp.612-621
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• 1996

In this paper, we propose the low sidelobe digital FIR doppler filter bank synthesis algorithm through the Gradient Descent method and it can be practially appliable to coherent pulse doppler radar signal processing. This algorithm shows the appropriate calculation of tap coefficients or zeros for FIR transversal fiter which has been employed in radar signal processor. The span of the filters in the filter bank be selected at the desired position the designer want to locate, and the lower sidelobe level that has equal ripple property is achieved than one for which the conventional weithtedwindow is used. Especially, when we implemented filter zeros as design parameters it is possible to make null filter gain at zero frequency intensionally that would be very efficient for the eliminatio of ground clutter. For the example of 10 tap filter synthesis, when filter coefficients or zeros are selected as design parameters the corresponding sidelobelevel is reducedto -70db or -100db respectively and it has good convergent characteristics to the desired sidelobe reference value. The accuracy ofapproach to the reference value and the speed of convergence that show the performance measure of this algorithm are tuned out with some superiority and the fact that the bandwidth of filter appears small with respect to one which is made by conventional weighted window method is convinced. Since the filter which is synthesized by this algorithm can remove the clutter without loss of target signal it strongly contributes performance improvement with which detection capability would be concerned.

• Journal of Electrical Engineering and information Science
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• v.2 no.3
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• pp.29-40
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• 1997

Two asymptotic analyses of the queue length distribution at a statistical multiplexor supporting heterogeneous exponential on-off sources are considered. The first analysis is performed by approximating the cell generation rates as a multi-dimensional Ornstein-Uhlenbeck process and then applying the Benes queueing formula. In the second analysis, w state with a system of linear equations derived from the exact expressions of the dominant eigenvalue of the matrix governing the queue length distribution. Assuming that there are a large number of sources, we obtain asymptotic approximations to the dominant eigenvalue. Based on the analyses, we define a traffic descriptor to include the mean and the variance of the cell generation rate and a burstiness measure. A simple expression for the quality of service (QoS) in cell loss rate is derived in terms of the traffic descriptor parameters and the multiplexor parameters (output link capacity and buffer size). The result is then used to quantify the factors determining the required capacity of a call taking the statistical multiplexing gain into consideration. As an application of the analyses, we can use the required capacity calculation for simple yet effective connection admission control(CAC) algorithms.

• Proceedings of the SAREK Conference
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• 2008.06a
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• pp.912-918
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• 2008

In this study, the exergy which could be reflected on energetic and economic value was used to assess on heat tariff of district heating system instead of enthalpy. Exergy is difficult to apply directly to present heat charge system because of complex calculation. Therefore, the difference between supply and return temperature was converted to the exergy temperature difference for easily calculating the amount of heat. As a result of exergy analysis for a DH substation, the exergy temperature difference were not affected on surrounding temperature and pressure loss. Supply temperature, maximum difference between supply temperature and return temperature had a main effect on the exergy temperature difference. The new heat charge of a DH user was slightly reduced in winter compared with previous heat charge. Heat charges in other seasons were almost same. It is thought that heat tariff using exergy will be appropriate in terms of both DH supplier and consumer.

• Proceedings of the Korean Nuclear Society Conference
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• 1997.10a
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• pp.772-777
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• 1997

Previous MELCOR and SCDAP/RELAP5 nodalizations for simulating the counter-current, natural circulation behavior of vapor flow within the RCS hot legs and SG U-tubes when core damage progress can not be applied to the steady state and water-filled conditions during the initial period of accident progression because of the artificially high loss coefficients in the hot legs and SG U-tubes which were chosen from results of COMMIX calculation and the Westinghouse natural circulation experiments in a 1/7-scale facility for simulating steam natural circulation behavior in the vessel and in the hot leg and SG during the TMLB' scenrio. The objective of this study is to develop a natural circulation modeling which can be used both for the liquid flow condition at steady state and for the vapor flow condition at the later period of in-vessel core damage. For this, the drag forces resulting from the momentum exchange effects between the two vapor streams in the hot leg was modeled as a pressure drop by pump model. This hot leg natural circulation modeling of MELCOR was able to reproduce similar mass flow rates with those predicted by previous models.