• Journal of international Conference on Electrical Machines and Systems
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• v.3 no.2
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• pp.229-234
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• 2014

In this paper, a design problem of the flywheel energy storage system controller using genetic algorithm (GA) is investigated for a frequency control of the wind diesel hybrid power generation system in an isolated power system. In order to select parameters of the FESS controller, two performance indexes are used. We evaluated a frequency control effect for the wind diesel hybrid power system according to change of the weighted values of a performance index. To verify performance of the FESS controller according to the weighted value of the performance index, the frequency domain analysis using a singular value bode diagram and the dynamic simulations for various weighted values of performance index were performed. To verify control performance of the designed FESS controller, the eigenvalue analysis and the dynamic simulations were performed. The control characteristics with the two designed FESS controller were compared with that of the conventional pitch controller. The simulation results showed that the FESS controller provided better dynamic responses in comparison with the conventional controller.

• Journal of the Korean Society of Food Science and Nutrition
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• v.26 no.3
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• pp.521-527
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• 1997

This study was aimed to investigate the nutriational status of Korean female college students who are attending school at a longdistance. Physique calssification by anthropomethic indexes, Body mass index(BMI) & Brocas' index and the body fat distrubition were investigated. The energy balance was also examined comparing caloric intake with caloric expenditure. The result of this study are followings; (1) Average height and weight were 158±17.8 cm, 51.7±7.8 kg. This results were not quite different from '84 Korean Adult Standard of 159.5cm, 52.5kg. (2) By Broca's index, 25.89% of subjects was underweight 67.0% was normal weight and 7.06 was overweight. By BMI, 40% of subjects was underweight, 58.8% was normal weight and 1.2% was overweight. (3) According to % fat measured. By BIA, 7% in subjects was underweight, 64.2% was normal weight, 22% was overweight and 6.1% was obesity. This result differed from BMI's result. It may be measurement error due to the difficulty of removing metal sticking to underwear and tooth correction. (4) The intakes of the nutrients except protein, P, vitamin B₁ complexes, were lower than the intakes indicated by Korean Recommended Allowances. 95) Average caloric intake a day was 1545±394.4 kcal, which was much lower than the RDA. The caloric expenditure was much more than caloric intake, which showed negative energy balance in the subjects of this study.

• KIEAE Journal
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• v.13 no.2
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• pp.131-139
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• 2013

The aim of this dissertation is establishing internal indicator list for achieving policy goal of Carbon Neutrality Green City. First of all, it started to construct the basic system of planning indicator based on through comprehension of current studies such as advanced researches, government guidelines and green building certifications. And then it was set up final indicator list through inspecting FGI (Focus Group Interview), Verification of suitability, and Analysis of importance). As a result of this research, the planning indicator divided three steps and there were classified four fields in the top-level; Green Land and Ecology, Green Energy, Green Resource and Transportation, Green Living and Institution. According to the data, it deducted four items (ratio of green land, site plan, heat island and management of climate, base of nature ecology) and twelve index in the field of green land and ecology, three item(energy conservation and self-supporting, energy efficiency, new regeneration energy) and twelve index in the field of green energy and regeneration, five items(water resources utilize and circulation, other resource reduction and circulation, public transportation, green transportation plan) and fifteen index. Totally, Planning Indicators of forty nine were deducted. Therefore, there was the result of importance analysis that the indicators of plan and maintain management as the side of space for carbon neutrality were more appreciated than carbon reduction of individual building.

• Earthquakes and Structures
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• v.2 no.2
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• pp.171-187
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• 2011

Rational scaling of design earthquake ground motions for tall buildings is essential for safer, risk-based design of tall buildings. This paper provides the structural designers with an insight for more rational scaling based on drift and input energy demands. Since a resonant sinusoidal motion can be an approximate critical excitation to elastic and inelastic structures under the constraint of acceleration or velocity power, a resonant sinusoidal motion with variable period and duration is used as an input wave of the near-field and far-field ground motions. This enables one to understand clearly the relation of the intensity normalization index of ground motion (maximum acceleration, maximum velocity, acceleration power, velocity power) with the response performance (peak interstory drift, total input energy). It is proved that, when the maximum ground velocity is adopted as the normalization index, the maximum interstory drift exhibits a stable property irrespective of the number of stories. It is further shown that, when the velocity power is adopted as the normalization index, the total input energy exhibits a stable property irrespective of the number of stories. It is finally concluded that the former property on peak drift can hold for the practical design response spectrum-compatible ground motions.

• Steel and Composite Structures
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• v.36 no.1
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• pp.31-45
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• 2020

The purpose of this study is to develop an effective iterative two-stage method (ITSM) for structural damage identification of offshore platform structures. In each iteration, a new damage index, Modal Energy-Based Damage Index (MEBI), is proposed to help effectively locate the potential damage elements in the first stage. Then, in the second stage, the beetle antenna search (BAS) algorithm is used to estimate the damage severity of these elements. Compared with the well-known particle swarm optimization (PSO) algorithm and genetic algorithm (GA), this algorithm has lower computational cost. A modal energy based objective function for the optimization process is proposed. Using numerical and experimental data, the efficiency and accuracy of the ITSM are studied. The effects of measurement noise and spatial incompleteness of mode shape are both considered. All the obtained results show that under these influences, the ITSM can accurately identify the true location and severity of damage. The results also show that the objective function based on modal energy is most suitable for the ITSM compared with that based on flexibility and weighted natural frequency-mode shape.

• Journal of Radiation Protection and Research
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• v.41 no.2
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• pp.101-104
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• 2016

Background: To protect the public from natural radioactive materials, the 'Act on safety control of radioactive rays around living environment" was established in Korea. There is an annual effective dose limit of 1 mSv for products, but the activity concentration limit for products is not established yet. Materials and Methods: To suggest the activity concentration limits for consumer goods containing NORM, in this research, we assumed the "small room model" surrounding the ICRP reference phantom to simulate the consumer goods in contact with the human bodies. Using the Monte Carlo code MCNPX, we evaluate the effective dose rate for the ICRP reference phantom in a small room with dimension of phantom size and derived the activity concentration limit for consumer goods. Results and Discussion: The consumer goods have about 1600, 1200 and $19000Bq{\cdot}kg^{-1}$ for $^{226}Ra$, $^{232}Th$ and $^{40}K$, and the activity concentration limits are about six times comparing with the values of building materials. We applied the index to real samples, though we did not consider radioactivity of $^{40}K$, indexes of the some samples are more than 6. However, this index concept using small room model is very conservative, for the consumer goods over than index 6, it is necessary to reevaluate the absorbed dose considering real usage scenario and material characteristics. Conclusion: In this research, we derived activity concentration limits for consumer goods in contact with bodies and the results can be used as preliminary screening tool for consumer goods as index concept.

• Transactions of the Korean Society of Automotive Engineers
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• v.5 no.2
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• pp.42-49
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• 1997

This experimental study was performed to find fuel property variations of the ultrasonic energy adding gasoline and improve the spray characteristics of the multipoint injector for EFI engine. The cause and effect of the characteristic improvement of the ultrasonic energy adding fuel was found out by the chemical structure analysis (NMR, IR), distillation and viscosity test. The results are obtained that the chemical property of gasoline organizition was changed aromatics to paraffins and branch index as the physical characteristics of gasoline were improved by ultrasonic energy. There were higher distillation and lower viscosity in ultrasonic energy adding gasoline.

• Journal of the Korean Solar Energy Society
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• v.22 no.3
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• pp.21-30
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• 2002

Images taken by geostationary satellite may be used to estimate solar irradiance fluxes at earth's surface. It is based on the empirical correlation between a satellite derived cloud index and the irradiance at the ground. For the validation. estimated solar radiation fluxes are compared with observed solar radiation fluxes at 16 sites over the Korean peninsular from January 1982 to December 2000. Estimated solar radiation fluxes show reliable results for estimating the global radiation with average deviation of -5.6 to +2.8% from the measured values and the yearly averaged horizontal global insolation of Korean peninsula was turned out to be $3.038kcal/m^2.day$.

• Steel and Composite Structures
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• v.15 no.4
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• pp.357-377
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• 2013

In order to study the degradation and damage behaviors of steel frame welded connections, two series of tests in references with different connection constructions were carried out subjected to various cyclic loading patterns. Hysteretic curves, degradation and damage behaviours and fatigue properties of specimens were firstly studied. Typical failure modes and probable damage reasons were discussed. Then, various damage index models with variables of dissipative energy, cumulative displacement and combined energy and displacement were summarized and applied for all experimental specimens. The damage developing curves of ten damage index models for each connection were obtained. Finally, the predicted and evaluated capacities of damage index models were compared in order to describe the degraded performance and failure modes. The characteristics of each damage index model were discussed in depth, and then their distributive laws were summarized. The tests and analysis results showed that the loading histories significantly affected the distributive shapes of damage index models. Different models had their own ranges of application. The selected parameters of damage index models had great effect on the developing trends of damage curves. The model with only displacement variable was recommended because of a more simple form and no integral calculation, which was easier to be formulated and embedded in application programs.

• Journal of Electrical Engineering and Technology
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• v.9 no.4
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• pp.1248-1257
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• 2014

Overhead transmission lines are crucial components in power transmission systems. Well-designed maintenance strategy for overhead lines is required for power utilities to minimize operating costs, while improving the reliability of the power system. This paper presents a maintenance priority index (MPI) of overhead lines for a reliability centered approach. Proposed maintenance strategy is composed of a state index and importance indices, taking into account a transmission condition and importance in system reliability, respectively. The state index is used to determine the condition of overhead lines. On the other hand, the proposed importance indices indicate their criticality analysis in transmission system, by using a load effect index (LEI) and failure effect index (FEI). The proposed maintenance method using the MPI has been tested on an IEEE 9-bus system, and a numerical result demonstrates that our strategy is more cost effective than traditional maintenance strategies.