Yoo S. Hong

An analytic network process approach to measuring design change impacts in modular products

Since parts and systems are closely linked to each other in complex engineering products, a change in a single part or system causes changes in other parts or systems, which in turn propagate through a product. This paper proposes an analytic network process (ANP) approach to measuring the relative importance of parts and modules in a modular product in terms of design change impacts and propagation. Although the primary purpose of the ANP is selection and prioritisation of alternatives, this study applies the ANP to change propagation by exploiting its advantageous feature, taking indirect impacts among elements into account. To begin with, a design dependency network that represents design change relationships among parts and modules is constructed as a network model of the ANP. The ANP procedure is then carried out to derive the relative change impacts (RCIs) of parts and modules. The RCI values can be used for various works in engineering change management. A case study on an automobile system is presented to illustrate the proposed approach.

Eco-architecture analysis for end-of-life decision making

In order to improve ease of disassembly and recycling of a product at its retirement stage, it is essential to design a product architecture that allows for easy disassembly and recycling. In this paper, a novel concept of eco-architecture is introduced, and the eco-architecture analysis, a design approach supporting the end-of-life decision making process, is proposed. The eco-architecture is the product architecture described from the end-of-life (EOL) viewpoint, in which a product is represented as an assembly of end-of-life modules. Not only does it prescribe an EOL strategy, but it also gives information about the connections and arrangement among EOL modules. Therefore, understanding the eco-architecture is helpful in enhancing the disassembly and recycling capabilities of an architecture design. The proposed eco-architecture analysis supports architecture improvement; it helps designers to derive the most desirable eco-architecture which entails the optimal end-of-life strategy. It also facilitates the extraction of meaningful redesign guidelines which make it possible to improve an architecture in an efficient and effective manner.

Dynamic disassembly planning for remanufacturing of multiple types of products

With the increased need for remanufacturing of end-of-life products, achieving economic efficiency in remanufacturing is urgently needed. The purpose of this study was to devise a cost-minimisation plan for disassembly and remanufacturing of end-of-life products returned by consumers. A returned end-of-life product is disassembled into remanufacturable parts, which are supposed to be used for new products after being remanufactured. Each end-of-life product is disassembled into parts at variable levels and through variable sequences as needed, taking into account not only disassembly but also manufacturing, remanufacturing, and holding inventory of remanufacturable parts. This study proposes a mixed integer linear programming (MILP) model for derivation of the optimal disassembly plan for each returned product, under deterministically known demand and return flows. For the purposes of an illustrative example, the proposed model was applied to the formulation of an optimal disassembly and remanufacturing plan of ‘fuser assembly’ of laser printers. The solution reveals that variable-level disassembly of products saves a significant remanufacturing cost compared with full disassembly.

Automatic derivation of transition matrix for end-of-life decision making

Recently strengthened environmental regulations have obligated manufacturing companies to treat end-of-life (EOL) products both environmentally consciously and economically. EOL treatment begins with disassembling a product into recyclable or disposable sub-assemblies. Therefore, the economic value of an EOL product is largely a function of the plan for its disassembly: the means by which it is to be disassembled into smaller sub-assemblies, and the choice of sub-assemblies to be disassembled first. In order to make these decisions, a disassembly structure describing every possible sub-assembly division and its disassembly path from the original product has to be presented in a typical form. A widely used form of such a structure is a transition matrix. A transition matrix shows all feasible sub-assemblies and their disassembly hierarchy. Whereas it can be easily transformed into mathematical disassembly planning problem, the tedious work required for its generation limits its practical use. In this paper, we propose an algorithm for automatic derivation of a transition matrix. The proposed algorithm provides an efficient way to derive a transition matrix based on a products architectural information, which includes the products physical connections and the relative geometric locations between individual parts. The algorithm was validated in deriving a transition matrix of a car door-trim. Our algorithm can significantly expand the applicability of transition-matrix-based disassembly planning research.

Evaluation of Acceleration Effect of Dynamic Sequencing of Design Process in a Multiproject Environment

The design process is difficult to accelerate due to its iterative nature, which increases project cost and delays completion time of a design project. Many previous studies tried to find the optimal structure and sequence of a design process minimizing iteration. In a multiproject environment, however, waiting time caused by resource shortage is a more critical reason for a lengthy project than iteration time. In this paper, we propose a novel sequencing method that reduces waiting time in a multiproject environment by dynamically changing the sequence of design tasks, according to availability of resources. It is called a dynamic sequencing method, as opposed to the traditional static sequencing method by which every design project follows a predefined optimal sequence. In order to evaluate the effect of this method, we developed a design-process model for simulating iteration and waiting in a multiproject environment. The simulation results show that dynamic sequencing is significantly better than traditional static sequencing with respect to average duration of projects. It is noted that more significant improvements can be obtained for the bottlenecked and unbalanced processes, both of which conditions would otherwise have negative effects on process performance.

A framework for designing balanced product platforms by estimating the versatility of components

Mass customisation is a common trend in many industries, and the platform-based product family strategy is a widely used method for this purpose. While the platform strategy can reduce the cost of variety by sharing common assets such as components and production processes, it has the risk of losing market share owing to its limitation on diversity. A balance between commonality and variety needs to be achieved when designing platforms that are both efficient and effective. In this paper, we focus on developing a platform that is versatile for highly effective differentiation to increase market share, incorporating the preferences of customers for different kinds of diversity. By distinguishing preferred and non-preferred diversity and ignoring the unnecessary need for differentiation, a platform designer can increase commonality without loss of market share. Under the assumption that a versatile platform is composed of versatile components, we estimate the versatility of components to identify the versatile ones. The estimation method consists of two phases: the market analysis phase, for identifying which specifications are preferred to be differentiated, and the product analysis phase, for assessing how much impact the differentiation may have on the component. A high versatility score indicates that the corresponding component is suitable for being platformed since it is not likely to be changed to increase market share. At the same time, a low versatility score provides a clue for improving the product architecture. The proposed method was applied to computer mouse design and yielded a reasonable platform plan.

Business Model Design Methodology for Innovative Product-Service Systems: A Strategic and Structured Approach

The business model is receiving considerable attention these days as companies achieve great success, or suffer damaging failure, by changing their way of doing business. Most of the literature on this subject has looked to establish the taxonomy, architecture, or constituent elements of business models, with the aim of isolating their key characteristics. However, only a few have dealt with supportive methodologies for business model design. The present study aims to provide a structured methodology for business model design. At the core of the methodology lies a design template with which a current business model can be analyzed or reinvented in a systematic manner. The template consists of a set of predefined building blocks that describes a business models strategic patterns and/or constituent elements, which building blocks were collected and verified through an investigation into more than one hundred real-world business model cases. In addition to the design template, a framework for new business model design also is provided. With the help of the representational schemes and procedures therein defined, one can design a business model in a more structured way. The framework is illustrated by means of a case study of an apparel company that set out to commercialize its newly designed product-service system concept.

Platform replacement planning for management of product family obsolescence

In our rapidly changing world, existing technologies quickly obsolesce and new technologies continually emerge. While it is desirable that product platforms are designed for long life spans, state-of-the-art products cannot be developed on platforms with obsolete technologies. The purpose of this study is to develop a model to determine the optimal lifetime of platforms trading-off the cost efficiency of platform development and lost sales due to obsolete technologies. In order to predict sales revenue with respect to platform lifetime, a stochastic product introduction model is developed based on a diffusion model. A computational analysis is performed to reveals the influence of platform features and the market situation on the optimal lifetime and profitability of platforms. Furthermore, the economic value of retarding the speed of obsolescence is assessed in order to glean insights into the design of a robust or flexible platform.

Data-driven optimized vehicle-level engineering specifications

Purpose – The purpose of this paper is to propose a methodology that determines vehicle-level specifications for new-car program by balancing market environments and engineering feasibility in the early stages of the vehicle development processes using statistical analysis of historical data. Design/methodology/approach – The proposed methodology effectively captures the interplay among key factors in preliminary vehicle planning: engineering feasibility constraints, market demands, and economic conditions. Engineering design constraints, derived by statistical analysis of historical data, define the strategic feasible space. Within the defined design space, the methodology determines a set of specifications that maximize the customer utility which is built as a function of preferences on each attribute of a vehicle. Findings – The present paper develops an “extrapolation” approach using historical vehicle data, rather than attempt to model a complex system with limited information. In doing so, the propo...

Human-Centered Event Description for Ubiquitous Service Computing

Ubiquitous computing environments are becoming the convergence of a variety of devices and technologies. The environments consist of a group of independently executing devices which have complicated functions on heterogeneous platforms. In this paper, a service-oriented architecture is presented to implement ubiquitous computing environments in which complex events occur from various sensors, communication devices, and web service providers. It is assumed that web services technologies will be more spread among the heterogeneous device platforms over the internet protocol.