• 유체기계공업학회:학술대회논문집
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• 2004.12a
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• pp.419-426
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• 2004

A three-dimensional computation was conducted to understand effects of the inlet boundary layer thickness on the loss mechanism in a low-speed axial compressor operating at the design condition(${\phi}=85\%$) and near stall condition(${\phi}=65\%$). At the design condition, the flow phenomena such as the tip leakage flow and hub comer stall are similar independent of the inlet boundary layer thickness. However, when the axial compressor is operating at the near stall condition, the large separation on the suction surface near the casing is induced by the tip leakage flow and the boundary layer on the blade for thin inlet boundary layer but the hub corner stall is enlarged for thick inlet boundary layer. These differences of internal flows induced by change of the boundary layer thickness on the casing and hub enable loss distributions of total pressure to be altered. When the axial compressor has thin inlet boundary layer, the total pressure loss is increased at regions near both casing and tip but decreased in the core flow region. In order to analyze effects of inlet boundary layer thickness on total loss in detail, using Denton's loss models, total loss is scrutinized through three major loss categories in a subsonic axial compressor such as profile loss, tip leakage loss and endwall loss.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.24 no.3
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• pp.289-294
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• 2011

In this study, the seismic analysis of traveling sea water screen for nuclear power plant was performed using finite element model. For qualification of traveling sea water screen, the response spectrum analysis was performed using the given operating basis earthquake(OBE) and safe shutdown earthquake(SSE) floor response spectrum. Dynamic analysis of water sea traveling screen was performed using finite element method. The analytical maximum displacements of traveling sea water screen were 2.5 mm under OBE condition and 4.6 mm under SSE condition. The maximum stresses of traveling sea water screen were 24 MPa under OBE condition and 44 MPa under SSE condition, that this results were 18 %, 27% of yield strength of material. Thus, it can shown that the structural integrity of traveling sea water screen has a stable structure for seismic load conditions.

• Journal of Korean Ophthalmic Optics Society
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• v.13 no.4
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• pp.155-160
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• 2008

Purpose: To develop a program for analyzing the condition of implanted ICL lenses in case the residual astigmatism appears after the implantation. Methods: From analyzing the measured residual astigmatism after operating ICL lens, we could induce formulas that produce the rotating angle and the corresponding MR prescription of the implanted ICL lens. Using the Delphi 6.0 language, we could develop a program by which we conveniently confirm, in the window screen visually, the rotating angle and the corresponding MR prescription of the implanted ICL lens calculated by these formulas. Results: We induced formulas that produce the rotating angle and the corresponding MR prescription of the implanted ICL lens by analyzing the measured residual astigmatism after operating ICL lens and developed a program which can analyze the condition of the implanted ICL lens. By this program we could easily analyze the condition of the implanted ICL lens. Conclusions: Judging from the results of applying this program to many clinical cases, we could conclude that this program is very effective in analyzing the condition of implanted ICL lenses.

• International Journal of Highway Engineering
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• v.13 no.4
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• pp.167-175
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• 2011

Evaluation of fuel consumption for the various road condition and vehicle type is necessary to perform the economic analysis of road construction which is important for the efficient design and management of road. Economic analysis of road should consider the social cost which can be divided into agency cost including initial construction expense, maintenance cost, and so on, and user cost consisting of vehicle operating cost, congestion cost, etc. Since vehicle operating cost depends on the traffic volume, fuel consumption that is a major part of vehicle operating cost will change by traffic volume as well. Fuel consumption is significantly affected by vehicle speed and road condition, especially the roughness. Thus, fuel consumption should be evaluated in terms of road condition, which is not currently considered. In this study, the estimation model of fuel consumption for the passenger cars in Korea has been developed by considering the road condition. First, the relationship between vehicle speed and fuel consumption that is used to calculate the vehicle operating cost for investment evaluation of transportation facility and the initial feasibility study of road construction was investigated. Second, with the consideration of road roughness, fuel consumption of the passenger car was measured. From the measurement, it was found that fuel consumption increased by $80m{\ell}$ per 100km driving as the roughness increased by 1m/km. Therefore, it is recommended that for the economic analysis of road design and management, the fuel consumption should be a function of road roughness.

• Proceedings of the KSME Conference
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• 2001.11a
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• pp.539-543
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• 2001

Almost all rotating machinery has bearings. Bearing is one of the most important part of rotating machinery. Vibration of rotating machinery depend on its bearing conditions. Bearing conditions are followings ; oil gap, bearing type, bearing temperature, bearing oil condition. Especially, bearing oil condition influences on rotating machinery vibration directly. In this paper we have discussed the abnormal vibration of turbine due to oil condition. oil whip problem was occured in the certain power plant. and we had sloved this problem through the control of operating values and alignment.

• Transactions of the Korean Society of Automotive Engineers
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• v.6 no.1
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• pp.80-89
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• 1998

The residual gas in an spark-ignition engine is one of important factors on emissions and performance such as combustion stability. With high residual gas fractions, flame speed and maximum combustion temperature are decreased and these are deeply related with combustion stability especially at idle and NOx emission at relatively high engine load. Therefore, there is a need to characterize the residual gas fraction as a function of the engine operating load. Therefore, there is a need to characterize the residual gas fraction as a function of the engine operating parameters. In the present study, the quantitative measurement technique of residual gas fraction was studied by using Fast Response Flame Ionization Detector(FRFID). The measuring technique and model for estimation of residual gas fraction were reported in this paper. By the assuming that the raw signal from FRFID saturates with the same slope for firing and misfiring cycle, in-cylinder hydrocarbon(HC) concentration can be estimated. Residual gas fraction can be obtained from the in-cylinder HC concentration measured at firing and motoring condition. The developed measurement and calibration procedure were applied to the limited engine operating and design condition such as intake manifold pressure and valve overlap. The results show relevant trends by comparing those from previous studies.

• Journal of Korean Society of Water and Wastewater
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• v.31 no.6
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• pp.611-618
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• 2017

Recently, applications of high voltage impulse (hereafter HVI) technique to desalting, sludge solubilization and disinfection have gained great attention. However, information on how the operating condition of HVI changes the water qualities, particularly production of hydroxyl radical (${\cdot}OH$) is not sufficient yet. The aim of this study is to investigate the effect of operating conditions of the HVI on the generation of hydroxyl radical. Indirect quantification of hydroxyl radical using RNO which react with hydroxyl radical was used. The higher HVI voltage applied up to 15 kV, the more RNO decreased. However, 5 kV was not enough to produce hydroxyl radical, indicating there might be an critical voltage triggering hydroxyl radical generation. The concentration of RNO under the condition of high conductivity decreased more than those of the low conductivities. Moreover, the higher the air supplies to the HVI reactor, the greater RNO decreased. The conditions with high conductivity and/or air supply might encourage the corona discharge on the electrode surfaces, which can produce the hydroxyl radical more easily. The pH and conductivity of the sample water changed little during the course of HVI induction.

• The KSFM Journal of Fluid Machinery
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• v.6 no.3 s.20
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• pp.36-43
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• 2003

Operating performance of industrial gas turbines in combined cycle power plants depends upon atmospheric conditions. Compressor fouling caused by airborne particles in the atmosphere and their adhesions on compressor blades is one of critical phenomena related to the performance degradation of industrial gas turbines. Compressor fouling provokes increase of pressure loss in inlet duct, decrease of mass flow rate of intake air and decrease of compressor stage efficiency. In this study, impacts of compressor fouling on the performance of an industrial gas turbine operating at design point condition are investigated analytically. As results, it is found that the reduction of produced power with decreased mass flow rate of intake air caused by narrowed flow area by the adhesion of airborne particles on compressor blades is the most dominant impact on the gas turbine performance by the compressor fouling phenomena.

• Transactions of the Korean Society of Mechanical Engineers
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• v.11 no.5
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• pp.846-855
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• 1987

The experimental study was carried out to investigate the performance characteristics of the aero-valved pulsating combustor designed to increase the practical applications of the system. The geometric effect on the stable condition and the dynamic behavior of the system is identified. The equivalence ratio, the inflammability limit, the operating frequency, and thrust were also measured when the system oscillated stably. It is found that while the operating condition is sensitive to the diameter of the inlet pipe and the length of the tailpipe, the maximum value of the turn down ratio was obtained up to 3.2. The measured air flow rate shows that the equivalence ratio increases monotonously with the increasing fuel flow rate and decreasing air inlet diameter and tailpipe length. The measured operating frequency can be approximated by the simple linear equation and the discrepancy is within five percent. The system produced the maximum total thrust of 14N and the minimum specific fuel consumption of 0.155 Nm$^{3}$/h.N when the total thrust was 13N.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.22 no.1
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• pp.29-33
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• 1986

This paper aims at finding out the optimum operating condition to reduce fuel consumption for the training ship Pusan 402 with controllable pitch propeller. For this purpose, this paper examints the variation of ship speed and fuel consumption in accordance with the change of engine revolution and propeller pitch. The results obtained are as follows: 1. When engine revolution is constant, the ship speed sluggishly increases according to the increase of propeller pitch but fuel consumption extremely increases. The higher revolution the engine is, the more remarkable this tendency is. 2. As the engine revolution becomes lower, the fuel consumption per mile decreases. Howt.er = the fuel consumption under the same engine revolution differs according to the propeller pitch. 3. Specific fuel consumption is uniformed about 180g/ps.h at any case of load. 4. Among the various operating conditions which yield the same ship speed, fuel consumption lowers in the case of lower engine revolution and larger propeller pitch.