Changes in Fruit Physicochemical Characteristics by Fruit Clusters in June-bearing Strawberry Cultivars

Three Korean-bred strawberry cultivars 'Maehyang', 'Seolhyang', and 'Keumhyang', and a Japanese cultivar 'Tochiotome' were grown in a greenhouse and their physicochemical characteristics were investigated. Fruit weight of 'Seolhyang' and 'Keumhyang' in the first and second fruit clusters were greater than those of other cultivars and that of 'Tochiotome' was the greatest in the fifth fruit cluster. Fruit firmness generally decreased at later fruit clusters, and was the lowest in 'Seolhyang'. The sugars/organic acids ratios in the first and third fruit clusters of 'Maehyang' were 4.9 and 8.0, respectively, representing the highest values among all cultivars. The ascorbic acid content was the greatest in the second fruit cluster for 'Seolhyang', 'Keumhyang', and 'Tochiotome' cultivars and that of 'Maehyang' was the greatest at the third fruit cluster. The anthocyanin content was higher in later fruit clusters and was the highest in 'Keumhyang' overall. Results indicate that Korean cultivars bred for the plastic protected culture, which are intended for very early harvest, showed more desirable physical characteristics in the first and second fruit clusters, while the content of anthocyanin was greater in the fruits from later fruit clusters.This work was carried out with the support of Cooperative Research Program for Agriculture Science & Technology Development (Project No.907002082012) Rural Development Administration, Republic of Korea.OAIID:oai:osos.snu.ac.kr:snu2012-01/102/0000027607/5SEQ:5PERF_CD:SNU2012-01EVAL_ITEM_CD:102USER_ID:0000027607ADJUST_YN:YEMP_ID:A075898DEPT_CD:517CITE_RATE:.237FILENAME:2012-8-kjhst-딸기과방별물리확학적특징-김성겸.pdfDEPT_NM:식물생산과학부EMAIL:[email protected]_YN:NCONFIRM:

Residual stresses in austenitic thin-walled pipe girth welds: Manufacture and measurements

Determining residual stresses in thin-walled pipes is challenging. They are potentially difficult targets for simulation, because they may not behave as simple axisymmetric structures during welding. Thin-walled pipes are more sensitive to changes in the welding heat input than thick-walled pipes. They are also under-represented in the existing population of residual stress measurements used to generate upper bound residual stress profiles for structural integrity assessments. In this paper, residual stress characterisation of two thin-walled austenitic girth welded pipes is presented. The overall geometries of the two mock-up designs were the same; they differed in the linear heat input per pass and the total number of weld passes. The residual stress characterisation was carried out using two independent measurement techniques; the contour method and neutron diffraction. The multiple-cut contour strategy was implemented to measure the cross-sectional maps of hoop and axial stresses on axial-radial and hoop-radial planes respectively. The contour method results are compared with stresses measured using neutron diffraction and specific residual stress distribution signatures observed are discussed

Combined Economic Emission Dispatch with Environment-Based Demand Response Using WU-ABC Algorithm

Owing to the growing interest in environmental problems worldwide, it is essential to schedule power generation considering the effects of pollutants. To address this, we propose an optimal approach that solves the combined economic emission dispatch (CEED) with maximum emission constraints by considering demand response (DR) program. The CEED consists of the sum of operation costs for each generator and the pollutant emissions. An environment-based demand response (EBDR) program is used to implement pollutant emission reduction and facilitate economic improvement. Through the weighting update artificial bee colony (WU-ABC) algorithm, the penalty factor that determines the weighting of the two objective functions is adjusted, and an optimal operation solution for a microgrid (MG) is then determined to resolve the CEED problem. The effectiveness and applicability of the proposed approach are demonstrated via comparative analyses at a modified grid-connected MG test system. The results confirm that the proposed approach not only satisfies emission constraints but also ensures an economically superior performance compared to other approaches. These results present a useful solution for microgrid operators considered environment issues

Two-Stage Optimal Microgrid Operation with a Risk-Based Hybrid Demand Response Program Considering Uncertainty

Owing to the increasing utilization of renewable energy resources, distributed energy resources (DERs) become inevitably uncertain, and microgrid operators have difficulty in operating the power systems because of this uncertainty. In this study, we propose a two-stage optimization approach with a hybrid demand response program (DRP) considering a risk index for microgrids (MGs) under uncertainty. The risk-based hybrid DRP is presented to reduce both operational costs and uncertainty effect using demand response elasticity. The problem is formulated as a two-stage optimization that considers not only the expected operation costs but also risk expense of uncertainty. To address the optimization problem, an improved multi-layer artificial bee colony (IML-ABC) is incorporated into the MG operation. The effectiveness of the proposed approach is demonstrated through a numerical analysis based on a typical low-voltage grid-connected MG. As a result, the proposed approach can reduce the operation costs which are taken into account uncertainty in MG. Therefore, the two-stage optimal operation considering uncertainty has been sufficiently helpful for microgrid operators (MGOs) to make risk-based decisions

Multi-Objective Scheduling Optimization Based on a Modified Non-Dominated Sorting Genetic Algorithm-II in Voltage Source Converter−Multi-Terminal High Voltage DC Grid-Connected Offshore Wind Farms with Battery Energy Storage Systems

Improving the performance of power systems has become a challenging task for system operators in an open access environment. This paper presents an optimization approach for solving the multi-objective scheduling problem using a modified non-dominated sorting genetic algorithm in a hybrid network of meshed alternating current (AC)/wind farm grids. This approach considers voltage and power control modes based on multi-terminal voltage source converter high-voltage direct current (MTDC) and battery energy storage systems (BESS). To enhance the hybrid network station performance, we implement an optimal process based on the battery energy storage system operational strategy for multi-objective scheduling over a 24 h demand profile. Furthermore, the proposed approach is formulated as a master problem and a set of sub-problems associated with the hybrid network station to improve the overall computational efficiency using Benders’ decomposition. Based on the results of the simulations conducted on modified institute of electrical and electronics engineers (IEEE-14) bus and IEEE-118 bus test systems, we demonstrate and confirm the applicability, effectiveness and validity of the proposed approach

Real Levelized Cost of Energy with Indirect Costs and Market Value of Variable Renewables: A Study of the Korean Power Market

A levelized cost of energy (LCOE) is a methodology for comparing power generation costs in the transition to renewable energy (RE). However, the major limitation of evaluating RE based on the LCOE is that it does not consider indirect costs, such as the environmental and curtailment effect. This paper proposes the real LCOE (rLCOE) approach that accounts for indirect and direct generation costs. The mathematical approach to estimating indirect costs is derived from economic theory. The indirect effects, which quantify all benefits generated due to RE, is related to the variability of the share RE in the energy generation mix. The rLCOE enhances the accuracy of the economic comparison of power generation costs and the derivation of the optimal quantities of RE because external effects are incorporated into the LCOE principles. This approach has taken into account electricity demand, fuel prices, and environmental costs for each energy source to adequately compare generation costs. Simulations have been performed to demonstrate the application of the rLCOE approach in the Korean power market. Here, the unit variation of costs with the RE share were analyzed. The results show that indirect cost savings of an additional unit of RE begin to fall in scenario 3 in contrast to the result of LCOE approach indicating higher generation costs with RE share, especially, the proportion of RE in the generation mix is higher than 20%. Thus, the optimal power generation can be evaluated using the rLCOE approach