• Journal of the Computational Structural Engineering Institute of Korea
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• v.13 no.3
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• pp.337-349
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• 2000

Genetic Algorithms(GA) together with simulated annealing are often called methods of last resorts since they can be applicable to any kind of problems, particularly those to which no sophisticated procedures are applicable or feasible. The design of structures is primarily the process of selecting a section for each member from those available in the market, resulting in the problem of combinatorial nature. Therefore it is usual for the design space to include astronomical number of designs making the search in the space often impossible. In this work, Genetic Algorithms and some related technique are introduced and applied to the design of steel frameworks. In problems with a small number of design variables, GA found true global optima. GA also found true optima for the continuous variable test problems and proved their applicability to structural optimization. For those problems of real size, however, it appears to be difficult to expect GA to find optimum or even near optimum designs. The use of G bit improvement added to ordinary GA has shown much better results and draws attention for further research.

• Journal of the Korean Institute of Gas
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• v.21 no.4
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• pp.76-83
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• 2017

Biogas, combine with ever-increasing natural gas demand, has been on the center stage in South Korea for the early part of twenty first century in an effort to reduce the emission of global warming gases. With the passage of legal system of City Gas Business Law in 2014, the biogas has its place of production and distribution to consumers. However, it has a room for its technological improvements in terms of enrichment, by separating carbon dioxide and removing impurities efficiently. For these improvements, four different methane enrichment processes were tested in this study; membrane separation, water absorption, Chemical Absorption and Adsorption. A variety of operation scenarios were applied to the processes and the best practices were drawn out. The optimum process was selected based on case study results. Methane produced in this study showed 97% purity and 98% recovery rate, which meets the requirements of the City Gas quality standards.

• Korean Journal of Food Science and Technology
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• v.47 no.6
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• pp.687-697
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• 2015

With the shortage of edible fats and oils and depletion of fossil fuels in many countries, microbial lipids is emerging as one of the most promising sources of fats and oils in the global market. Oleaginous microorganisms, also called single cell oils (SCOs), can accumulate lipids more than 25% in the cell volume. Triacylglycerols are the major storage lipids. SCOs offer several advantages for lipid production as follows: SCOs have short life span which would shorten production time, cultivation conditions are not affected by climate and place; the production process is easy to control. There are a number of oleaginous yeasts, molds, and microalgae. Furthermore, the lipid productivity of SCOs can be enhanced through strain improvement and the optimization of cultivation conditions. The new strains developed using recent advanced biotechnical methods showed greatly improved oleaginicity. Further, hydrolysates of lignocellulosic materials can be used as carbon sources for economic production of SCO.

• Proceedings of the Korean Society of Near Infrared Spectroscopy Conference
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• 2001.06a
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• pp.1154-1154
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• 2001

Near infra-red (NIR) spectroscopy has been used for the non-invasive assessment of intact fruit for eating quality attributes such as total soluble solids (TSS) content. However, little information is available in the literature with respect to the robustness of such calibration models validated against independent populations (however, see Peiris et al. 1998 and Guthrie et al. 1998). Many studies report ‘prediction’ statistics in which the calibration and prediction sets are subsets of the same population (e. g. a three year calibration validated against a set from the same population, Peiris et al. 1998; calibration and validation subsets of the same initial population, Guthrie and Walsh 1997 and McGlone and Kawano 1998). In this study, a calibration was developed across 84 melon fruit (R$^2$= 0.86$^{\circ}$Brix, SECV = 0.38$^{\circ}$Brix), which predicted well on fruit excluded from the calibration set but taken from the same population (n = 24, SEP = 0.38$^{\circ}$Brix with 0.1$^{\circ}$Brix bias), relative to an independent group (same variety and farm but different harvest date) (n = 24, SEP= 0.66$^{\circ}$ Brix with 0.1$^{\circ}$Brix bias). Prediction on a different variety, different growing district and time was worse (n = 24, SEP = 1.2$^{\circ}$Brix with 0.9$^{\circ}$Brix bias). Using an ‘in-line’ unit based on a silicon diode array spectrometer, as described in Walsh et al. (2000), we collected spectra from fruit populations covering different varieties, growing districts and time. The calibration procedure was optimized in terms of spectral window, derivative function and scatter correction. Performance of a calibration across new populations of fruit (different varieties, growing districts and harvest date) is reported. Various calibration sample selection techniques (primarily based on Mahalanobis distances), were trialled to structure the calibration population to improve robustness of prediction on independent sets. Optimization of calibration population structure (using the ISI protocols of neighbourhood and global distances) resulted in the elimination of over 50% of the initial data set. The use of the ISI Local Calibration routine was also investigated.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.59 no.12
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• pp.2202-2211
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• 2010

The wind power prediction system is composed of a meteorological forecasting module, calculation module of wind power output and HMI(Human Machine Interface) visualization system. The final information from this system is a short-term (6hr ahead) and mid-term (48hr ahead) wind power prediction value. The meteorological forecasting module for wind speed and direction forecasting is a combination of physical and statistical model. In this system, the WRF(Weather Research and Forecasting) model, which is a three-dimensional numerical weather model, is used as the physical model and the GFS(Global Forecasting System) models is used for initial condition forecasting. The 100m resolution terrain data is used to improve the accuracy of this system. In addition, optimization of the physical model carried out using historic weather data in Jeju. The mid-term prediction value from the physical model is used in the statistical method for a short-term prediction. The final power prediction is calculated using an optimal adjustment between the currently observed data and data predicted from the power curve model. The final wind power prediction value is provided to customs using a HMI visualization system. The aim of this study is to further improve the accuracy of this prediction system and develop a practical system for power system operation and the energy market in the Smart-Grid.

• Journal of Intelligence and Information Systems
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• v.11 no.1
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• pp.191-205
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• 2005

This paper presents a novel product recommender system as a tool fur differentiated marketing service of online shopping malls. Ihe proposed model uses genetic algorithnt one of popular global optimization techniques, to construct a personalized product recommender systen The genetic algorinun may be useful to recommendation engine in product recommender system because it produces optimal or near-optimal recommendation rules using the customer profile and transaction data. In this study, we develop a prototype of WeLbased personalized product recommender system using the recommendation rules fi:om the genetic algorithnL In addition, this study evaluates usefulness of the proposed model through the test fur user satisfaction in real world.

• Journal of Ocean Engineering and Technology
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• v.26 no.4
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• pp.37-41
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• 2012

Due to global warming, the need to secure alternative resources has become more important nationally. Because of the very strong current on the west coast, with a tidal range of up to 10 m, there are many suitable sites for the application of TCP (tidal current power) in Korea. In the southwest region, a strong current is created in the narrow channels between the numerous islands. A rotor is an essential component that can convert tidal current energy into rotational energy to generate electricity. The design optimization of a rotor is very important to maximize the power production. The performance of a rotor can be determined using various parameters, including the number of blades, shape, sectional size, diameter, etc. There are many offshore jetties and piers with high current velocities. Thus, a VAT (vertical axis turbine) system, which can generate power regardless of flow direction changes, could be effectively applied to cylindrical structures. A VAT system could give an advantage to a caisson-type breakwater because it allows water to circulate well. This paper introduces a multi-layer vertical axis tidal current power system. A Savonius turbine was designed, and a performance analysis was carried out using CFD. A physical model was also demonstrated in CWC, and the results are compared with CFD.

• Journal of Advanced Marine Engineering and Technology
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• v.37 no.1
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• pp.47-52
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• 2013

The higher energy efficiency for ship and the lower pollution for global environment are required strictly. However the performance of marine diesel engine is gradually deteriorated with time. And also the operation condition is varied with sea conditions. Hence the optimization for operating condition of marine engines is needed for energy saving and environment kindly. In this paper, it was attempted to investigate the influence of aging for marine diesel engine. The deterioration of engine performance is assessed by the calculation results of the simulation program for two-stroke marine diesel engine developed by author which was reported before. And three parameters for deterioration of engine performance were considered such as lower efficiency of turbocharger by fouling, increase of blow-by gas due to wear of cylinder liner and getting worse of combustion by poor injection. By the results, it was shown that the influence of engine performance by aging was relatively not so small - 10.4 bar low in Pmax and 3.2% decrease in Pmi.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.14 no.9
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• pp.1972-1978
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• 2010

AAM(Active Appearance Model) is one of the most effective ways to detect deformable 2D objects and is a kind of mathematical optimization methods. The cost function is a convex function because it is a least-square function, but the search space is not convex space so it is not guaranteed that a local minimum is the optimal solution. That is, if the initial value does not depart from around the global minimum, it converges to a local minimum, so it is difficult to detect face contour correctly. In this study, an AAM-based face tracking algorithm is proposed, which is robust to various lighting conditions and backgrounds. Eye detection is performed using SIFT and Genetic algorithm, the information of eye are used for AAM's initial matching information. Through experiments, it is verified that the proposed AAM-based face tracking method is more robust with respect to pose and background of face than the conventional basic AAM-based face tracking method.

• Journal of Convergence Society for SMB
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• v.2 no.1
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• pp.69-75
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• 2012

As the global warming and climate change cause the various social problems, such as disasters, abnormal temperature and diseases, technologies and studies for energy conservation and efficiency are increased. Energy use in buildings accounted for 22% of national energy use, so energy saving technology is promoted for residence, commercial and public buildings. Existing methods for energy conservation are passive ways, in that they consider heat loss and low-energy equipment. In recent years, active technologies emerge by converging with ICT, which detect and remove the energy waste situation by measuring, monitoring and controlling the energy use. In this paper, we describe technology trends for building energy optimization and investigates issues for active energy savings.