Research Trends and Outlooks in Assembly Line Balancing Problems

This paper presents the findings from the survey of articles published on the assembly line balancing problems (ALBPs) during 2014-2018. Before proceeding a comprehensive literature review, the ineffectiveness of the previous ALBP classification structures is discussed and a new classification scheme based on the layout configurations of assembly lines is subsequently proposed. The research trend in each layout of assembly lines is highlighted through the graphical presentations. The challenges in the ALBPs are also pinpointed as a technical guideline for future research works

The Evolution of Work

The division of labor first increased during industrialization and then decreased again after 1970 as job roles have expanded. We explain these trends in the organization of work through a simple model where (a) machines require standardization to exploit economies of scale and (b) more customized products are subject to trends and fashions which make production tasks less predictable and a strict division of labor impractical. At the onset of industrialization, the market supports only a small number of generic varieties which can be mass-produced under a strict division of labor. Thanks to productivity growth, niche markets gradually expand, producers eventually move into customized production and the division of labor decreases again. The model predicts capital-skill substitutability during industrialization and capital skill complementarity in the maturing industrial economy. Moreover, conventional calculations of the factor content of trade underestimate the impact of globalization because they do not take into account changes in product market competition induced by trade. We test our model by exploiting the time-lags in the introduction of bar-coding in three-digit SIC manufacturing industries in the US. We find that both increases in investments in computers and bar-coding have led to skill-upgrading. However, consistent with our model bar-coding has affected mainly the center of the skill distribution by shifting demand away from the high-school educated to the less-than-college educated.

Real and Monetary Challenges to Wage Policy in Germany at the Turn of the Millennium: Technical Progress, Globalization and European Monetary Union

At the turn of the millennium three frequently cited potential causes of new challenges for wage p olicy in Germany are revisited in this study: skilled-biased technological progress, the increasing international integration of labor and product markets, and the monetary integration of the EMU. While there is now a fairly broad consensus on the basic fa cts about the development of wages and employment across skill groups, there is considerable disagreement to explain these trends, in particular to what extent skill-biased technical change and trade liberalization share a major responsibility. The conclusion of this paper is that both factors are at work with a slight emphasis on the first candidate. Moreover, while EMU in our opinion does not represent the major threat for wage policy, it is the Single Market which requires wage policy to be on the lookout and to meet those challenges.Monetary UnionWages, wage structure, skill-biased technological change, international trade, European Monetary Union, globalisation, globalization

임시 작업자를 활용한 혼합모델 조립라인의 통합적 균형화 연구

학위논문 (석사)-- 서울대학교 대학원 : 산업공학과, 2015. 2. 문일경.이 논문은 단일 제품을 조립하는 일반적인 조립라인 균형화 문제를 복수 제품들을 동시에 조립할 수 있는 혼합 모델 조립라인으로 확장하였으며, 임시 작업자를 고용하여 조립라인을 효율화할 수 있도록 하였다. 이를 고려한 세 가지 버전의 수학적 모형들을 개발하였다. 각 모형의 목표는 모든 직원의 임금과 작업장 비용을 합친 총 비용을 최소화하는 것, 작업장 수가 주어진 상황에서 사이클 시간을 최소화하는 것, 그리고 정해진 작업장 안에서 업무 과부하를 최소화하는 것이다. 제안된 모형들은 숙련된 작업자와 임시 작업자를 동시에 할당하는 사안과 작업들 사이의 선행관계 등 실제 현장에서 적용되는 실용적 특성들을 고려하고 있다. 뿐만 아니라, 총 비용을 최소화할 수 있는 복합유전알고리즘도 개발되었다. 해의 타당성을 보장하고 복합유전알고리즘의 우수성을 높이기 위해 특별한 유전연산자들과 발견적 기법이 사용되었다. 수치실험들을 통해서 복합유전알고리즘의 우수성을 입증하기 위하여 수학적 모형과 비교하였다.This study extends a single-model assembly line balancing problem to an integrated mixed-model assembly line balancing problem by incorporating temporary unskilled workers, who enhance productivity. Three mathematical models are developed to minimize the sum of total workstation costs, salaries of all workers, and cycle times and potential work overload of a predetermined number of workstations. The proposed models are based on particular features of the real-world problem, such as simultaneous assignments of skilled and temporary unskilled workers as well as precedent restrictions among the tasks. Furthermore, a hybrid genetic algorithm that minimizes total operation costs is developed. Special genetic operators and heuristic algorithms are used to ensure feasibility of solutions and make the hybrid genetic algorithm efficient. Computational experiments demonstrate the superiority of the hybrid genetic algorithm over the mathematical models.Chapter 1. Introduction 1 1.1 The assembly line 1 1.1.1 Characteristics of assembly line problem 1 1.1.2 Assembly line balancing problem 2 1.2 The mixed-model assembly line 3 1.2.1 Characteristics of mixed model assembly line problem 3 1.2.2 Mixed model assembly line balancing problem 4 1.3 Literature review 5 1.4 Contributions 9 Chapter 2. Mathematical Models 11 2.1 General features of mathematical models 11 2.2 Problem description 11 2.3 Model Ⅰ 14 2.4 Model Ⅱ 18 2.5 Model Ⅲ 20 Chapter 3. A Hybrid Genetic Algorithm 23 3.1 Chromosome representation 24 3.2 Objective and fitness function 26 3.3 Genetic operator 27 3.3.1 Selection 27 3.3.2 Crossover 28 3.3.3 Mutation 29 3.4 Terminating conditions and parameters 30 Chapter 4. Computational Experiments 31 4.1 Experiments for Model Ⅰ 39 4.2 Experiments for Model Ⅱ 42 4.3 Experiments for Model Ⅲ 46 4.4 Validation of a hybrid genetic algorithm 48 Chapter 5. Conclusions 50 Bibliography 51 Abstract 54Maste

Workforce management in manual assembly lines of large products: a case study

Assembly lines are used for a large variety of products in different industrial sectors. In this paper the focus is placed on complex assembly systems and workstations used for the final assembly of large and bulk products, such as trucks, aircrafts, buses, tool machines. An high number of tasks to be performed at a single assembly station, several workers involved in parallel in the assembly process and long Takt times make such systems different from the models intensively studied in the literature (e.g. the traditional Simple Assembly Line Balancing Problem). This study firstly presents a new balancing model to address the problem of the total cost minimization when different operator skills are involved at the same time and then it applies the model to a real industrial case

IWS briefing, Winter 2005 Volume 5 Issue 1

[Excerpt] A newsletter on workplace issues and research from the School of Industrial and Labor Relations at Cornell University

The NAFTA: another futile trade area (AFTA) or a serious approach towards regionalism?

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Formulation of simple workforce skill constraints in assembly line balancing models

The objective of assembly line balancing (ALB) is to minimize the number of workstations organized to perform tasks with precedence constraints. An important element of proper assignment of tasks to workstations is the consideration of skill requirement of tasks, and skill level of workers. Some tasks may require special skills, some workers might not be able to perform complicated tasks, and some workers might be specialized for specific tasks. This paper provides a general framework to model skill requirements and skill conditions for assembly line balancing models. Three types of skill constraints are defined. Low skill constraints determine workstations for workers who are able to perform only some simple tasks. High skill constraints consider tasks which require higher than average skills of workers. Finally, exclusive skill constraints consider situations where a group of workers is specialized in a subset of tasks. The paper summarizes the mathematical description of the different skill constraints, and shows how simple assembly line balancing models can be completed with skill considerations. The mathematical characteristics of the resulting models are discussed, and some sample problems are solved to illustrate the results of each specific skill situation

Labour Flexibility and productivity: an Inquiry into the Thai Labour Regime”.

Knowledge is presented as the new driving force of competitiveness. It is usually defined as including formal innovation such as R&D and all forms of learning opportunities occurring during economic activities like work and relations with suppliers and customers. Our communication will focus on knowledge, labour markets and work in the context of Thailand. Thailand is an interesting case because it is representative of second-tier high-growth Asian economies, and most of all, because it is a full-employment economy. This means that if workers are not satisfied with their job, they can easily change their employer. If the company wants to retain them, they have to offer something in exchange: higher wages, bonus, and welfare allowances. This has consequences for the diffusion of knowledge. When workers' mobility is high and employment tenure low, workers are the conduits through which knowledge is transferred across firms, leading to possible increases in productivity. When firms prefer to create an internal labour market in order to retain their workers and accumulate knowledge internally, the diffusion of knowledge relies on linkages between firms and their customers. Our objective is to assess the viability of these scenarios in Thailand. We start with a short analysis of the state of science, technology and education in Thailand (section 1). The conclusion is that formal knowledge is lagging behind and that improvements will take time. The diffusion of knowledge through workers' mobility does not seem viable at this stage and the accumulation of knowledge in internal labour market is a better option. Because internal labour markets involve high employment tenure, we then turn to the analysis of mobility and employment tenure (section 2). The objective is to see if there is any tendency towards the strengthening of internal labour markets. We use an in-depth field survey realised by the Centre for Education and Labour Studies (Chiang Mai University, Thailand). This is the first nation-wide survey on these topics. A questionnaire has been applied to interview 1543 industrial workers, staff employees and engineers in 85 private and state companies and to 1567 self-employed and 454 employees of the informal sector. Data on education, workers mobility, employment tenure, wages, bonuses and welfare have been collected and are analysed in the paper. The results show that several elements characteristics of internal labour markets are present in big companies with higher than average technological intensity. International comparisons show that average employment tenure in Thailand is intermediate, inferior to the European and Japanese levels but close to the US level, and much higher than in Latin American countries. We conclude that Thailand has the potential to improve its competitiveness by upgrading the level and the quality of education and by strengthening internal labour markets. Competitiveness could be based on the accumulation of knowledge with a positive impact on productivity rather than cheap labour.Thailand, Labour Flexibility, Internal Labour Market, Employment, Tenure