• Journal of the Korean Society of Propulsion Engineers
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• v.12 no.1
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• pp.44-50
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• 2008

In this study a turboshaft engine for a helicopter propulsion system was modeled using SIMULINK and the components' maps were generated from the limited performance deck data provided by engine supplier using a hybrid method with the genetic algorithms and the system identification method. In order to verify the SIMULINK performance model and the component maps generated by the hybrid method, the steady-state performance analysis results were compared with the performance data provided by engine manufacturer. In this investigation, it was confirmed that the analysis results by the proposed model are closely met with those by engine manufacturer's data.

• Journal of Korean Institute of Industrial Engineers
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• v.6 no.1
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• pp.17-22
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• 1980

The performance of scientific researchers has been studied from a number of different aspects, mostly in developed countries. This paper attempted to identify salient factors influencing scientific performance at individual level in a developing country. A model describing the productivity and performance of scientific researchers was developed. Four hypotheses were derived from the model; i) the degree of diversity of a researcher will affect the degree of his scientific performance, ii) the degree of dedication will affect the degree of his performance, iii) the degree of research pressure will affect the degree of his performance, and iv) the degree of satisfaction will affect the degree of his performance. Data were collected through questionnaires responded by 48 researchers from two research organizations. The results of data analysis supported the hypotheses in part. Specifically, diversity measured by the number of research areas was related to the productivity of research reports (p<0.05); research pressure influenced the average number of research papers (p<0.05). The results of hypothesis testing of the satisfaction showed mixed directions according to the indicators. Even though the results of data analysis did not support the hypotheses unanimously, probably due to the limitation of sample size, most of the descriptive analysis indicated that the direction of hypotheses in developed countries seemed to be similar in developing country too. However, more research efforts are needed to verify the research findings of developed countries in developing countries.

• Korea-Australia Rheology Journal
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• v.21 no.4
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• pp.289-297
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• 2009

We numerically analyzed flow characteristics of the polymer melt in the screw equipment using a proper modeling and investigated design parameters which have influence on the mixing performance as the capability of the screw equipment. We considered the non-Newtonian and non-isothermal flow in a single rotor equipment to investigate the mixing performance with respect to screw dimensions as shape parameter of the single rotor equipment and screw speed as process parameter. We used Bird-Carreau-Yasuda model as a viscous model of the polymer melt and the particle tracking method to investigate the mixing performance in the screw equipment and considered four mixing performance indexes: residence time distribution, deformation rate, total strain and particle standard deviation as a new mixing performance index. We compared these indexes to determine design parameters and object function. On basis of the analysis results, we carried out the optimal design by using the response surface method and design of experiments. In conclusion, the differences of results between the optimal value and numerical analysis are about 5.0%.

• Journal of the Korean Society of Safety
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• v.25 no.3
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• pp.83-90
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• 2010

In this study, it is conducted that the performance verification of the ambient load carrying capacity algorithm using long-term measurement systems of bridges. For this purpose, a steel-box type model bridge is fabricated and the public load carrying capacity of a steel-box model bridge is estimated by conducting the numerical analysis and load test. In addition, we compare the public load carrying capacity with the estimated result of a steel-box model bridge using the ambient load carrying capacity algorithm. By the assessment result, it is shown that the estimated ambient load carrying capacity is the difference of approximately 6.0 percentages as compared with the public load carrying capacity.

• Structural Engineering and Mechanics
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• v.53 no.3
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• pp.589-605
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• 2015

The use of the rigid polyurethane foam (RPF) to strengthen buried structures against blast terror has great interests from engineering experts in structural retrofitting. The aim of this study is to use the RPF to strengthen the buried structures under blast load. The buried structure is considered to study the RPF as structural retrofitting. The Guowei model (Guowei et al. 2010) is considered as a case study. The finite element analysis (FEA) is also used to model the buried structure under shock wave. The buried structure performance is studied based on detonating different TNT explosive charges. There is a good agreement between the results obtained by both the Guowei model and the proposed numerical model. The RPF improves the buried structure performance under the blast wave propagation.

• Proceedings of the IEEK Conference
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• 2002.07b
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• pp.963-966
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• 2002

This paper presents a new generic Petri net model for design and performance evaluation of a flexible assembly system with dual kanban. The architectural design of the model is derived from a generic bill of materials and the combination of FMS and FAS concepts. Two approaches for analysis and performance evaluation of the new model base on the theory of invariant analysis and linear programming are also introduced. Finally, the effect of different processing times between FMS-FAS on the number of kanban cards is investigated.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.12 no.7
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• pp.649-658
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• 2000

Thermodynamic modeling of low-pressure scroll compressor was developed by combining continuity and energy conservation equation. Suction gas heating was considered using energy balance inside the low pressure shell. Pressure, temperature and mass of refrigerant-22 as a function of orbiting angle were calculated by solving the governing equations using fourth order Rung-Kutta scheme. Motor efficiency was taken by experiments with a variation of frequency. The developed model was applied to the analysis of an inverter driven scroll compressor with a variation of frequency, pressure ratio and operating conditions. The model was verified with the experimental results at the same operating conditions. The developed model was adequate to predict performance of the inverter driven scroll compressor as a function of operating conditions. Calculated parameters from the model were discharge temperature, mass flow rate, power input, COP, and thermodynamic properties with respect to orbiting angle. To enhance the performance of a scroll compressor, it is essential to diminish leakage at low frequency level and improve the mechanical efficiency at high frequency level.

• International Commerce and Information Review
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• v.12 no.4
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• pp.279-302
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• 2010

A better selection model on management innovative enterprises is needed since the Korean government provides multi benefits to those selected enterprises. However, the selection model's propriety is suspicious because of the shortage of consideration of assessment items. In particular, the most important two assessment items, strategy and performance are suspected of multicollinearity because of high correlation scores. No consideration on multicollinearity among those items leads to erroneous selection which doubly counts the same components with different item names. The principle component analysis is applied to factor out the uncorrelated items. Using the resulted principle components, the new estimations are carried out. The comparison between estimated results from using principle components and non principle components shows that the present selection model overly considers the performance items compared to the real effect of items, which is a result of multicollinearity between performance and strategy.

• Transactions of the Korean Society of Automotive Engineers
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• v.12 no.4
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• pp.146-153
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• 2004

This paper presents a discrete analysis approach to investigate the performance of dual mass flywheel (DMF). In the discrete analysis, arcspring installed between the flywheels is modeled as N- discrete elements. Each element consists of mass, spring and nonlinear friction element. LuGre friction model is used to describe nonlinear friction characteristic. Based on the dynamic models of the DMF, clutch, engine, manual transmission and vehicle, a DMF performance simulator is developed using MATLAB Simulink. Simulation results of the engine speed, driveshaft torque and vehicle velocity are compared with test results. It is found that the discrete DMF model describes the vehicle behavior closely, especially during the clutch actuation period.

• Special Issue of the Society of Naval Architects of Korea
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• 2015.09a
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• pp.41-45
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• 2015

In this study reviewed the validity of the estimated optimum trim by the numerical analysis. For this purpose, the numerical analysis of the trim optimization for 6500TEU container carrier and capesize bulk carrier were carried out using Star-CCM+, which results were compared with the results of model tests. The reliability of results of the numerical analysis was confirmed via comparing the resistance determined by the numerical analysis and model test. The performance of self-propulsion at each trim conditions were estimated using the calculated resistance by numerical analysis. The BHP at each trim condition were calculated by estimated performance of self-propulsion, which trend of results were confirmed similar trend of result of model test.