• Solar Energy
• /
• v.10 no.1
• /
• pp.63-79
• /
• 1990

It has been recognized that a policy for supplying solar house and hot water production systems utilizing solar energy needs to be driven to save civilian comsuming energy or to develop alternative energy. However, the economic feasibility study of solar energy systems must be carried out before their practical use. The purpose of this study is to furnish information for supplying policy and enlightening users with the economic feasibility study of solar house and hot water production systems. Decision support systems are established to carry out economic analysis on solar systems more accurately. Therefore, computer simulation is carried out to analyze the performance of solar systems and also economic feasibility study by trial and error method is carried out. Fuel cost and additional cost for solar systems are estimated employing present worth concept and economic analysis has been conducted using the break-even point analysis method and life-cycle cost analysis method.

• Proceedings of the Korean Society for Technology of Plasticity Conference
• /
• 1999.08a
• /
• pp.69-77
• /
• 1999

Roll profile design in spape rolling with a complex-shaped part depends on the designer's experience, which is general, is acquired through costly trial-and-error process. As a prerequisite for developing a scientific approach to roll profile design, we present a finite element model to simulate 3-D deformation of complex-shaped parts occuring in multi-pass sequence. Demonstrated is the process model's capability to deal with rolling of a complex-shaped part.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 1995.10a
• /
• pp.638-641
• /
• 1995

The model-technology has been conduced to a large quantity of automobile and electric products. However, many problems in mold-technology have been solved through trial and error of experts. So it has given rise to overdesign of mold and generated other problems in production line. In this paper we choosed the lower-mold of a cool chamber in refrigerator as the model of the study and mass reduced overdesigned mold. In mass reduction process, several cases in plane processing error were selected for the sample case through FEM analysis & simplicated theory analysis and each case was evaluated for mass reduction.

• Geomechanics and Engineering
• /
• v.22 no.1
• /
• pp.97-108
• /
• 2020

The time-consuming and less objectivity are the main problems of conventional micromechanical parameters calibration method of Particle Flow Code simulations. Thus this study aims to address these two limitation of the conventional "trial-and-error" method. A new calibration method for the linear parallel bond model (CM-LPBM) is proposed. First, numerical simulations are conducted based on the results of the uniaxial compression tests on limestone. The macroscopic response of the numerical model agrees well with the results of the uniaxial compression tests. To reduce the number of the independent micromechanical parameters, numerical simulations are then carried out. Based on the results of the orthogonal experiments and the multi-factor variance analysis, main micromechanical parameters affecting the macro parameters of rocks are proposed. The macro-micro parameter functions are ultimately established using multiple linear regression, and the iteration correction formulas of the micromechanical parameters are obtained. To further verify the validity of the proposed method, a case study is carried out. The error between the macro mechanical response and the numerical results is less than 5%. Hence the calibration method, i.e., the CM-LPBM, is reliable for obtaining the micromechanical parameters quickly and accurately, providing reference for the calibration of micromechanical parameters.

• Transactions of Materials Processing
• /
• v.7 no.3
• /
• pp.225-232
• /
• 1998

This article is aimed primarily at establishing a process planning method for complex circular shells. For the deep drawing of complex shaped shell, the optimum process design is required to reduce the trial cost improve the quality, increase the productivity and shorten the delivery. The present approach which is related to the optimum process planning is based on the empirical knowledge through trial and error in the industrial field. In order to check the validity and the effectiveness of proposed work a sample process design has been applied to the multi-stepped deep drawing of com-plex shell considering the process variables such as drawing rate radius and blank development. In particular the difference between the limiting drawing rate and to optimum drawing rate has been discussed and the usefulness of present suggestion has been shown.

• Proceedings of the Korean Society for Technology of Plasticity Conference
• /
• 1998.03a
• /
• pp.160-167
• /
• 1998

This article is aimed primarily at establishing a process planning method for complex circular shells. For the deep drawing of complex shaped shell, the optimum process design is required to reduce the trial cost, improve the quality, increase the productivity and shorten the delivery. The present approach which is related to the optimum process planning is based on the empirical knowledge through trial and error in the industrial field. In order to check the validity and the effectiveness of proposed work, a sample process design has been applied to the multi-stepped deep drawing of complex shell considering the process variables such as drawing rate, radius and blank development. In particular, the difference between the limiting drawing rate and the optimum drawing rate has been discussed and has been shown the usefulness of present suggestion.

• The Journal of the Acoustical Society of Korea
• /
• v.42 no.3
• /
• pp.169-180
• /
• 2023

The performance of underwater acoustic communication is greatly affected by multipath propagation and Doppler spread. This paper proposes a new communication technique, the Triangle Spread Carrier (TSC) technique, by modifying the existing Sweep Spread Carrier (SSC) technique that is strong in a multipath propagation environment. The proposed TSC technique is a form in which the up-chirp and down-chirp signals have repeated carriers, and each correlation function characteristic is used to estimate and correct the Doppler shift frequency of the receiving signal. To demonstrate the performance of the proposed TSC technique, we present the results of simulations using underwater channel simulators and sea trial conducted in the East Sea. When demodulating using only the estimated Doppler shift frequency as a result of the sea trial, the uncoded bit error rate was up to 0.194, but when the proposed method was applied, the uncoded bit error rate was reduced to 0.001.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.15 no.9
• /
• pp.1871-1880
• /
• 2011

In this paper, a controller for two wheeled inverted pendulum robot, i.e., Segway type robot that is a convenient and easily handled vehicle is designed to have more stable balancing and faster velocity control compared to the conventional method. First, a widely used PID control structure is applied to the two wheeled inverted pendulum robot and proper PID control gains for some specified weights of users are obtained to get accurate balancing and velocity control by use of experimental trial-and-error method. Next, neural network is employed to generate appropriate PID control gains for arbitrarily selected weight. Here the PID gains based on the trial-and-error method are used as training data. Simulation study has been carried out to find that the performance of the designed controller using the neural network is more excellent than the conventional PID controller in terms of faster balancing and velocity control.

• The Journal of the Korea institute of electronic communication sciences
• /
• v.18 no.3
• /
• pp.535-544
• /
• 2023

In this paper, we study the effect of gradient vector calculation method(analytical method, central finite difference method) on adaptive beamforming to control weight distribution during iterated calculation when LMS algorithm (repeating method) is used to realize desired beam pattern. To this end, a quasi-ideal beam having an arbitrarily set beam width, a rotating beam, and a multi-beam were reviewed as examples. Numerical experiments applied the step parameters of the appropriate values to the adaptive beamforming system through trial and error equally to the two calculations, and compared the convergence characteristics of objective functions that evaluate adaptability and error using two methods for calculating gradient vectors.

• Water for future
• /
• v.6 no.1
• /
• pp.29-35
• /
• 1973

For the simplicity in the analytical solution, the simple surge tank has been chosen for the test where an unsteady flow is porduced by suddenly closing the valve controlling the discharge. The valve is loated immediately downstream from the surge tank. Momentumn equations in the penstock and in the surge column are measured recored on the oscillograph and then the calibration of surge column heights and scale readings on the oscillograph trace are made. The diameter of the penstock are determined by the trial and error method. The water levels in the surge column are computed by numerical integration of the differential equation of the surge tank. The relationships between the results from the experiment and numerical computation are figured, compared and discussed.