• Journal of the Korean Society for Nondestructive Testing
• /
• v.11 no.2
• /
• pp.42-47
• /
• 1991

Nondestructive evaluation study was made on creep damage materials by ultrasonic spectrum analysis. The evaluation methods was developed in order to predict the change of ultrasonic attenuation with increasing creep damage. A new algorithm for the improvement of measuring accuracy of ultrasonic attenuation using a spectrum analysis has been developed. Normally, the ultrasonic attenuation is evaluated from 1st and 2nd peak values of the pulse-echo ultrasonic wave. The algorithm developed is incorporated in a measuring system which consists of a personal computer with ultrasonic apparatus and a digital storage oscilloscope. By the spectrum analysis method, it become popssible to describe approximately the attenuation change with increassing creep damage in Cr-Mo-V forging.

• Journal of Environmental Science International
• /
• v.4 no.3
• /
• pp.221-228
• /
• 1995

Stability of reactor and effect on biofilm characteristics were investigated by varying the hydraulic residence time in an inverse fluidized bed biofilm reactor(IFBBR). The SCOD removal efficiency was maintained above 90 % in the HRT range of 12hr to 2hr, but the TCOD removal efficiency was dropped down to 50% because of biomass detachment from overgrown bioparticles. The reactor was stably operated up to the conditions of HRT of 2hr and F/M ratio of 4.5kgCOD/$m^3$/day, but above the range there was an abrupt increase of filamentous microorganisms. The optimum biofilm thickness and the biofilm dry density in this experiment were shown as $200\mu\textrm{m}$ and $0.08 g/cm^3$, respectively. The substrate removal rate of this system was found as 1st order because the biofilm was maintained slightly thin by the increased hydraulic loading rate.

• 한국전산유체공학회:학술대회논문집
• /
• 2007.10a
• /
• pp.100-110
• /
• 2007

A new design approach for a delicate treatment of complex geometries such as a wing/body configuration is arranged using overset mesh technique under large scale computing environment for turbulent viscous flow. Various pre- and post-processing techniques which are required of overset flow analysis and sensitivity analysis codes are discussed for design optimization problems based on gradient based optimization method (GBOM). The overset flow analysis code is validated by comparing with the experimental data of a wing/body configuration (DLR-F4) from the 1st Drag Prediction Workshop (DPW-I). In order to examine the applicability of the present design tools, careful design works for the drag minimization problem of a wing/body configuration are carried out by using the developed aerodynamic shape optimization tools for the viscous flow over multiple-body aircraft geometries.

• Journal of KSNVE
• /
• v.8 no.3
• /
• pp.441-449
• /
• 1998

A self-tuning control scheme, incorporated with the simplified 1st-order ARMAX(Auto-Regressive Moving Average eXogenous) model, for single rod hydraulic cylinder which has varying dynamic characteristics is presented here. An adaptive controller is developed for the system that uses feedforward and optimal feedback control for simultaneous parameter identification and tracking control. Through experimental results, the performance comparison of the self-tuning controller with a fixed gain proportional controller clearly shows its superior ability in handling load changes in quiescent states.

• Journal of the Korean Institute of Telematics and Electronics
• /
• v.20 no.5
• /
• pp.31-36
• /
• 1983

The indirect M.R.A.C. method using the W.L.S. algorithm is applied to the speed control of a D.C. motor on the assumption that the motor is the 1-st order, completely controllable and observable, non-minimum phase plant. By the help of M6809 microprocessor system the experiments are performed with respect to the sinusoidal and square reference input. The results show that the speed of a D.C. motor is well controlled by the indirect M.R.A.C. method using W.L.S, algorithm, and that the W.L.S. algorithm is quite suitable to the time-varying plant.

• Proceedings of the SAREK Conference
• /
• 2007.11a
• /
• pp.155-160
• /
• 2007

This study describes thermal performance of Plus50 eco-building with new technology such as power window system, green wall, structure material, etc. The Plus50 eco-building is house experimental which is constructed by Korea Institute of Construction Technology. In order to estimate thermal performance of the building, TRNSYS program and Prebid, and its sub-modules are used. The results showed that maximum heating and cooling load in the building are calculated at 1st floor and 4th floor, respectively. And also energy saving of the building is calculated as over 30% compared to conventional apartment house.

• Proceedings of the Korean Institute of Building Construction Conference
• /
• 2013.11a
• /
• pp.216-219
• /
• 2013

The objective of this study is an assessment of competitiveness in construction infrastructure by nation in order to provide preliminary data of government policy. Key results indicated that out of 23 countries, Korea's construction market size ranked 11th, construction market growth rate ranked 16th, market stability ranked 14th, construction risk ranked 4th, construction system ranked 10th, ICT ranked 1st. And Korea was ranked 10th in overall construction infrastructure competitiveness by nation.

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.67 no.9
• /
• pp.1232-1238
• /
• 2018

This paper proposes methods for improving mass spectral resolution for a gas chromatograph mass spectrometer. The slope signs of the 1st and 2nd fitting functions for the ion signal block of each mass index are obtained, and the unnecessary element signals in the ion signal block are removed. The spectrum can be obtained by obtaining the second-order fitting function of the reconstructed ion signal block using only the effective ion signals. In addition, the resolution of the mass spectrum can be improved by correcting the error caused by the shift of the spectral peak position. To verify the performance of the proposed methods, computer simulations were performed using the actual ion signals obtained from the GC-MS system under development. Simulation results show that the proposed method is valid.

• Journal of Korean Society of Industrial and Systems Engineering
• /
• v.29 no.4
• /
• pp.75-82
• /
• 2006

The main objective of this study is to find out the shortest path of the vehicle routing problem with time window constraints by using both genetic algorithm and heuristic. Hard time constraints were considered to the vehicle routing problem in this suggested algorithm. Four different heuristic rules, modification process for initial and infeasible solution, 2-opt process, and lag exchange process, were applied to the genetic algorithm in order to both minimize the total distance and improve the loading rate at the same time. This genetic algorithm is compared with the results of existing problems suggested by Solomon. We found better solutions concerning vehicle loading rate and number of vehicles in R-type Solomon's examples R103 and R106.

• Journal of Korea Multimedia Society
• /
• v.22 no.8
• /
• pp.930-939
• /
• 2019

High-Level Architecture(HLA)/Run-Time Infrastructure(RTI) are standards for distributed simulation systems and offer a technology to interconnect them and form one single simulation system. In defense domain, M&S is the only way to prove effectiveness of weapon systems except for Live Fire Testing (LFT). This paper focuses on guided missile simulations in weapon systems for engagement analyses and proposes the integrated flying vehicle model that is based on HLA/RTI. There are a lot of missiles in real world; therefore, we should develop each missile models in M&S in order to apply battlefield scenarios. To deal with the difficulties, in this paper, firstly, I classify these missiles into three models: ballastic, cruise, and surface-to-air missile models, and then I design each missile model and integrates them into a single model. This paper also offers a case study with my integrated flying vehicle model. At the conclusion, this paper presents contributions of this paper.