• 대한기계학회논문집A
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• 제25권10호
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• pp.1597-1604
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• 2001

Alternative computational scheme is presented fur reliability based optimal design using a modified advanced first order second moment (AFOSH) method. Both design variables and design parameters are considered as random variables about their nominal values. Each probability constraint is transformed into a sub -optimization problem and then is resolved with the modified Hasofer- Lind-Rackwitz-Fiessler (HL-RF) method for computational efficiency and convergence. A method of design sensitivity analysis for probability constraint is presented and tested through simple examples. The suggested method is examined by solving several examples and the results are compared with those of other methods.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2000년도 추계학술대회논문집A
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• pp.795-800
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• 2000

In a parallel manipulator, there are three constraints that determine workspace: link length constraint, passive joint angle constraint, and interference among links. Generally, the link length constraint is the most dominant. The interference among links is, however, also an important parameter in designing a desired parallel manipulator. In this study, the interference among links is mathematically modeled by considering the links as a line and a cylinder of radius of twice the link radius, and a new algorithm is suggested to check if arbitrary two links interfere each other or not. The workspace of a cubic parallel manipulator is illustrated in a 2D space satisfying the three constraints.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제11권11호
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• pp.5324-5337
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• 2017

In this paper, we investigate the feasibility of interference alignment(IA) in signal space in the scenario of multiple cell and multiple user cellular networks, as the feasibility issue is closely related to the solvability of a multivariate polynomial system, we give the mathematical analysis to support the constraint condition obtained from the polynomial equations with the tools of algebraic geometry, and a new distribute IA algorithm is also provided to verify the accessibility of the constraint condition for symmetric system in this paper. Simulation results illustrate that the accessibility of the constraint condition is hold if and only if the degree of freedom(DoF) of each user can be divided by both the transmit and receive antenna numbers.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제11권5호
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• pp.2346-2361
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• 2017

A major challenge in cloud infrastructure is the efficient allocation of virtual network elements on top of substrate network elements. Path algebra is a mathematical framework which allows the validation and convergence analysis of the mono-constraint or multi-constraint routing problems independently of the network topology or size. The present study proposes a new heuristic approach based on mathematical framework "paths algebra" to map virtual nodes and links to substrate nodes and paths in cloud. In this approach, we define a measure criterion to rank the substrate nodes, and map the virtual nodes to substrate nodes according to their ranks by using a greedy algorithm. In addition, considering multi-constraint routing in virtual link mapping stage, the used paths algebra framework allows a more flexible and extendable embedding. Obtained results of simulations show appropriate improvement in acceptance ratio of virtual networks and cost incurred by the infrastructure networks.

• 산업경영시스템학회지
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• 제38권2호
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• pp.145-151
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• 2015

As order quantity is increased, the ordering cost per item will be cheaper due to saving of transportation and material handling costs. In this paper, two realistic assumptions such as quantity discount and budget limit are considered. Quantity discount means that all units in the order will be discounted according to the predetermined order levels. Budget limit represents that the costs for inventory investments are bounded. This paper develops a Lagrangian relaxation approach for a continuous review inventory model with a budget constraint and quantity discounts. Computational results indicate that the proposed approach provides a good solution. Sensitivity analysis is done to get some insights on budget limit and quantity discount. As budget limit or the amount of discount according to order quantity is increased, order quantity is increased, whereas reorder point is not always increased.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2001년도 추계학술대회논문집 II
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• pp.1370-1375
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• 2001

Substructure coupling or component mode synthesis may be employed in the solution of dynamic problems for structure. The model is partitioned into several subdomains. and a generalized Craig-Bampton representation is derived. In this paper the mode sets(normal modes. constraint modes) have been employed for model reduction. A generalized model reduction procedure has been described. Those reduction methods which adapt constraint modes have been described in detail. As examples. a flexible structure and a 10 DOF damped system are analyzed. Comparison with a conventional reduction method based on a complete model has been made via eigenpairs and dynamic responses.

• Journal of Welding and Joining
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• 제15권4호
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• pp.63-69
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• 1997

Welding distortion is more serious problem than any other problems caused by welding process, especially, in the heavy-industrial place. These welding distortions are caused by nonuniform heating and cooling of metal during and after welding operations. And these distortion quantities are must be known to worker in production line because distorions are important role in assembling part. Therefore an analytical model to explain and predict the welding distortion are needed. A numerical analysis of welding distortion which is inelastic behavior of weldment would require the three dimensional calculation. But computing time and memory would be very large, and the resulting cost might be unacceptable. Therefore we use a numerical technique for two dimensional analysis in the section normal to the weld direction of weldment under an assumption of quasi-stationary conditions. But the result of the calculation under two dimensional(plane strain) assumption was not satisfied as compared with experimental result. This paper proposed a technique for analysing the welding angular distortion by using a constraint boundary condition on the two dimensional finite element model. The simulation results revealed that the constraint boundary model could more reasonably describe the welding distortion than the plane strain model did.

• Biotechnology and Bioprocess Engineering:BBE
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• 제10권5호
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• pp.408-417
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• 2005

Increasing numbers of value added chemicals are being produced using microbial fermentation strategies. Computational modeling and simulation of microbial metabolism is rapidly becoming an enabling technology that is driving a new paradigm to accelerate the bioprocess development cycle. In particular, constraint-based modeling and the development of genome-scale models of industrial microbes are finding increasing utility across many phases of the bioprocess development workflow. Herein, we review and discuss the requirements and trends in the industrial application of this technology as we build toward integrated computational/experimental platforms for bioprocess engineering. Specifically we cover the following topics: (1) genome-scale models as genetically and biochemically consistent representations of metabolic networks; (2) the ability of these models to predict, assess, and interpret metabolic physiology and flux states of metabolism; (3) the model-guided integrative analysis of high throughput 'omics' data; (4) the reconciliation and analysis of on- and off-line fermentation data as well as flux tracing data; (5) model-aided strain design strategies and the integration of calculated biotransformation routes; and (6) control and optimization of the fermentation processes. Collectively, constraint-based modeling strategies are impacting the iterative characterization of metabolic flux states throughout the bioprocess development cycle, while also driving metabolic engineering strategies and fermentation optimization.

• Nuclear Engineering and Technology
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• 제52권7호
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• pp.1579-1586
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• 2020

Dissimilar metal joints (DMJs) are more common in the application of piping system of many industries. A 2- D and 3-D finite element analysis (FEA) is carried out on dissimilar metal Single Edged Notch Bending (DMSENB) specimens fabricated from ferritic steel, austenitic steel and Inconel - 182 alloy to study the behavior of DMJs with constraints by using linear elastic fracture mechanics (LEFM) principles. Studies on DMSENB specimens are conducted with respect to (i) dissimilar metal joint width (DMJW) (geometrical constraints) (5 mm, 10 mm, 20 mm, 30 mm and 50 mm) (ii) strength mismatch (material constraints) and (iii) crack lengths (16 mm, 20 mm and 24 mm) to study the DMJ behavior. From the FEA investigation, it is observed that (i) SIF increases with increase of crack length and DMJWs (ii) significant constraint effect (geometry, crack tip and strength mismatch) is observed for DMJWs of 5 mm and 10 mm (iii) stress distribution at the interfaces of DMSENB specimen exhibits clear indication of strength mismatch (iv) 3-D FEA yields realistic behavior (v) constraint effect is found to be significant if DMJW is less than 20 mm and the ratio of specimen length to the DMJW is greater than 7.4.

• 가족자원경영과 정책
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• 제17권1호
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• pp.241-263
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• 2013

Time pressure and financial burden have been reported as the main constraints on leisure participation. The purpose of this study was to explore a typology of leisure constraints, investigate the characteristics of leisure constraint types, and analyze the differences in leisure participation by the types of leisure constraints for married employees. The data source for this research was the 2009 Time Use Survey conducted by the Korea National Statistical Office (KNSO). Married employees aged 20 to 59 years completed 13,476 time diaries (7,984 for male, 5,492 for female), which were analyzed using chi-square, cluster analysis, and ANOVA analysis. Leisure constraints were classified into five types in two categories, working time per week and personal income for both males and females respectively. The three types for both males and females were time-income constraints, income constraints, and general constraints, with an additional type for men, $time^+$-income constraints, and an additional type for women, time constraint. The most common type was general constraints, for both males and females. Each type was further differentiated by the following socio-economic variables: age, educational level, job type, and weekly day-off. The study found that participation in study, sports, and religious activities varied with the types of leisure constraints.