• Structural Engineering and Mechanics
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• 제76권5호
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• pp.561-578
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• 2020

The present work addresses the surface integrity and chip morphology in finish hard turning of AISI D3 steel under nanofluid assisted minimum quantity lubrication (NFMQL) condition. The surface integrity aspects include microhardness, residual stress, white layer formation, machined surface morphology, and surface roughness. This experimental investigation aims to explore the feasibility of low-cost multilayer (TiCN/Al2O3/TiN) coated carbide tool in hard machining applications and to assess the propitious role of minimum quantity lubrication using graphene nanoparticles enriched eco-friendly radiator coolant based nano-cutting fluid for machinability improvement of hardened steel. Combined approach of central composite design (CCD) - analysis of variance (ANOVA), desirability function analysis, and response surface methodology (RSM) have been subsequently employed for experimental investigation, predictive modelling and optimization of surface roughness. With a motivational philosophy of "Go Green-Think Green-Act Green", the work also deals with economic analysis, and sustainability assessment under environmental-friendly NFMQL condition. Results showed that machining with nanofluid-MQL provided an effective cooling-lubrication strategy, safer and cleaner production, environmental friendliness and assisted to improve sustainability.

• 산업경영시스템학회지
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• 제46권4호
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• pp.63-73
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• 2023

This study explores modern portfolio theory by integrating the Black-Litterman portfolio with time-series clustering, specificially emphasizing K-shape clustering methodology. K-shape clustering enables grouping time-series data effectively, enhancing the ability to plan and manage investments in stock markets when combined with the Black-Litterman portfolio. Based on the patterns of stock markets, the objective is to understand the relationship between past market data and planning future investment strategies through backtesting. Additionally, by examining diverse learning and investment periods, it is identified optimal strategies to boost portfolio returns while efficiently managing associated risks. For comparative analysis, traditional Markowitz portfolio is also assessed in conjunction with clustering techniques utilizing K-Means and K-Means with Dynamic Time Warping. It is suggested that the combination of K-shape and the Black-Litterman model significantly enhances portfolio optimization in the stock market, providing valuable insights for making stable portfolio investment decisions. The achieved sharpe ratio of 0.722 indicates a significantly higher performance when compared to other benchmarks, underlining the effectiveness of the K-shape and Black-Litterman integration in portfolio optimization.

• 약학회지
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• 제52권5호
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• pp.407-411
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• 2008

Phosphorylation plays the most important role in cell signaling mechanism. Various methods to identify the phosphorylation sites of proteins using tandem mass spectrometry (MS/MS) have been reported recently. Furthermore, the enrichment strategy such as Titanium dioxide ($TiO_2$) method should be combined with MS/MS analysis to effectively identify phosphorylation sites. It is necessary to optimize phosphopeptide-enrichment strategy, $TiO_2$ method in this study, due to the low amount of phosphorylated form followed by analyzing them by MS/MS. To evaluate the several conditions to enrich phosphopeptides using $TiO_2$ method, we used ${\apha}$-casein as a standard phosphoprotein and analyzed a representative phosphopeptide (VPQLEIVPNpSAEER) peak of MS spectrum. Batch is better than column method for binding and 300 g/l DHB in loading buffer is better than lower concentration of DHB. 3% TFA and pH 10.5 shows high efficiency of phosphopeptide-enrichment for washing and elution steps, respectively. Finally we identified various efficient conditions of phosphopeptide-enrichment method using $TiO_2$. This optimized method would assist in reliable identifying thousands of phosphorylation sites existed in low abundance from various complex proteins.

• Earthquakes and Structures
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• 제22권5호
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• pp.487-502
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• 2022

China is prone to earthquake disasters, and the higher seismic performance is required by many existing civil buildings. And seismic evaluation and retrofit are effective measures to mitigate seismic hazards. With the development of performance-based seismic design and diverse retrofit technology for buildings, advanced evaluation methods and retrofit strategies are in need. In this paper, we introduced the evolution of seismic performance objectives in China combined with performance-based seismic design. Accordingly, multi-phase evaluation methods and comprehensive seismic capacity assessment are introduced. For buildings with seismic deficiency or higher performance requirements, the retrofit technologies are categorized into three types: component strengthening, system optimization, and passive control. Both engineering property and social property for the retrofit methods are discussed. The traditional seismic retrofit methods usually are costly and disturbing, and for example in Beijing, seismic strengthening costs approx. 1000 RMB/m² (for 160 USD/m²), for hospital building even more expensive as 5000 RMB/m²(for 790 USD/m²). So cost-efficient and little disturbance methods are promising techniques. In the end, some opinions about the retrofit strategy and schemes category are shared and wish to discuss the situation and future of seismic retrofit in China.

• Journal of the Korean Data and Information Science Society
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• 제20권6호
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• pp.973-982
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• 2009

파론도 게임은 두 개의 지는 게임을 주기적으로 반복하거나 혹은 임의적으로 선택하면 궁극적으로 이기게 되는 역설적인 게임을 말한다. 여러 명의 게임자들이 파론도 게임을 구성하는 두 게임 중에서 하나를 집단적으로 선택해서 진행하는 게임을 고려하자. 본 논문에서는 이 집단 파론도 게임의 모든 모수의 범위에서 장기적으로 기대상금을 최대화하는 최적의 게임 선택 기준이 무엇인지를 찾고 그 기대상금을 구한다.

• 대한산업공학회지
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• 제23권3호
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• pp.451-467
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• 1997

Tabu search (TS) is a useful strategy that has been successfully applied to a number of complex combinatorial optimization problems. By guiding the search using flexible memory processes and accepting disimproved solutions at some iterations, TS helps alleviate the risk of being trapped at a local optimum. In this article, we propose TS-based heuristics for solving a class of clustering problems, and compare the relative performances of the TS-based heuristic and the simulated annealing (SA) algorithm. Computational experiments show that the TS-based heuristic with a long-term memory offers a higher possibility of finding a better solution, while the TS-based heuristic without a long-term memory performs better than the others in terms of the combined measure of solution quality and computing effort required.

• Journal of Electrical Engineering and Technology
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• 제10권2호
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• pp.641-646
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• 2015

In this paper, a zinc electrowinning cell is fully optimized to achieve a uniform current distribution at electrode surfaces. To effectively deal with an electromagnetically coupled problem with multi-dimensional design variables, a sampling-based sensitivity approach is combined with a highly tuned multiphysics simulation model. The model involves the interrelation between electrochemical reactions and electromagnetic phenomena so as to predict accurate current distributions in the electrowinning cell. In the sampling-based sensitivity approach, Kriging-based surrogate models are generated in a local window, and accordingly their sensitivity values are extracted. Such unique design strategy facilitates optimizing very complicated multiphysics and multi-dimensional design problems. Finally, ten design variables deciding the electrolytic cell structure are optimized, and then the uniformity of current distribution in the optimized cell is examined through the comparison with existing cell designs.

• 경영과학
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• 제29권2호
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• pp.21-34
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• 2012

This paper addresses a network design problem in a supply chain system that involves locating both plants and distribution centers, and determining the best strategy for distributing products from the suppliers to the plants, from the plants to the distribution centers and from the distribution centers to the customers. This paper suggests a cooperative coevolutionary algorithm (CCEA) approach to solve the model. First, the problem is decomposed into three subproblems for each of which the chromosome population is created correspondingly. Each chromosome in each population is represented as a permutation denoting the priority. Then an algorithm generating a solution from the combined set of chromosomes from each population is suggested. Also an algorithm evaluating the performance of a solution is suggested. An experimental study is carried out. The results show that our CCEA tends to generate better solutions than the previous CCEA as the problem size gets larger and that the permutation representation for chromosome used here is better than other representation.

• International journal of advanced smart convergence
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• 제9권1호
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• pp.98-108
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• 2020

We consider transmit antenna selection combined with power allocation for quadrature spatial modulation (QSM) systems to improve the error rate performance. The Euclidean distance-based joint optimization criterion is presented for transmit antenna selection and power allocation in QSM. It requires an exhaustive search and thus high computational complexity. Thus its reduced-complexity algorithm is proposed with a strategy of decoupling, which is employed to successively find transmit antennas and power allocation factors. First, transmit antennas are selected without considering power allocation. After selecting transmit antennas, power allocation factors are determined. Simulation results demonstrate considerable performance gains with lower complexity for transmit antenna selected QSM systems with power allocation, which can be achieved with limited rate feedback.

• 대한토목학회논문집
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• 제12권1호
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• pp.59-70
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• 1992

공학 및 구조최적설계에서 광범위하게 이용되고 있는 2차계획문제(QP)의 효율적인 해법을 개발하기 위하여, 먼저 QP의 해법으로 사용가능한 수학적 최적화기법들의 이론적 및 수치적 특성을 비교연구하였다. 원래 QP 및 쌍대 QP에 대하여 이론적 강건성이 확인된 심플렉스, 경사투영(GRP) 그리고 증대 라그란지승수 알고리즘의 컴퓨터 프로그램을 작성하고 수치적 수행성이 검토되었다. 연구결과, 잠재제약조건방책을 이용하는 원래 QP의 GRP 알고리즘과 쌍대 QP의 심플렉스 알고리즘이 다른 QP해법에 비하여 효율적이면서 강력한 방법임을 알 수 있었고, 제약함수의 수가 설계변수의 수보다 많을 때는 원래 QP의 GRP 알고리즘이 더욱 효율적이었다. 또 GRP 알고리즘과 심플렉스 알고리즘의 장점을 선별적으로 이용할 수 있는 조합 알고리즘이 제안되었다.