Changmuk Kang

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.

Product-Service System : Current Status and Research Issues

Korea University Business School (KUBS).Product-service system (PSS) is a novel type of business model integrating products and services in a single system. It provides a strategic alternative to product-oriented economic growth and price-based competition in the global market. This paper first reviews the current status of PSS, including its concept, characteristics, benefits, and cases. This paper then reviews the existing literature and identifies major research issues for three main phases of a PSS development lifecycle, namely, PSS design, PSS evaluation, and PSS operation. This research is expected to contribute to promoting awareness and improving understanding of PSS in our society and planning of future research in this field.

A Relation-based Model for Analyzing Ecosystems of Products, Services and Stakeholders

Business School, Korea University, Seoul 136-701, KoreaA central theme in recent IT (information technology) industry is a mobile ecosystem. While a concept of business ecosystem, which is an economic community of firms and individuals producing and consuming goods and services, has been around for about 20 years now, the recent spotlight is mainly caused by the enormous success of iPhone. Many hand-set makers or platform developers want to mimic Apple’s iPhone ecosystem from which both application developers and hand-set users can benefit. In this study, a representation model of the business ecosystem is proposed for supporting systematic design and analysis of ecosystems. Whereas previous studies also proposed some representation models, they emphasized only on the value chain between parti-cipating players. The proposed model, which is named relation-based ecosystem model, represents an ecosystem with the requirement relationships between product and service components and the roles of players, as well as their value chain. Such comprehensive representation explicitly reveals the strategic difference between ecosy-stems. This advantage was illustrated by comparing a Korean traditional mobile ecosystem and an emerging smart-phone ecosystem represented by the proposed model.

An adaptive crashing policy for stochastic time-cost tradeoff problems

We consider a stochastic time-cost tradeoff problem that determines how much to crash activities with the purpose of minimizing the expected summation of crashing and tardiness costs. We propose a threshold policy that makes a crashing decision contingent on a project?s current status; crashing an activity to compensate delayed starting time from a predetermined threshold. First, we present a dynamic programming (DP) formulation to find the threshold values, and prove that the resulting threshold policy is optimal for a serial-graph project. Since the above optimality does not hold generally, we develop a DP-based procedure to construct a threshold policy for arbitrary-graph projects.We show through the computational experiments that our threshold policy is rapidly constructed by this procedure, and its cost is not very far from the theoretical lower bound. HighlightsWe consider a stochastic time-cost tradeoff problem.We present a dynamic programming (DP) formulation for the adaptive threshold policy.We show that the policy is optimal for a serial-graph project.We develop a heuristic for arbitrary-graph projects.We verify through the computational experiments that the heuristic is better than the previous heuristics.

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...

Risk Propagation Through a Platform: The Failure Risk Perspective on Platform Sharing

A product platform is a set of subsystems and interfaces that are commonly shared by a variety of products. Although platform sharing is considered an effective means of cost saving, it also runs the risk of propagating a particular failure across multiple products when the platform is defectively designed. Thus, sharing a common platform effectively can amplify the risk of incurring a large number of failures. In this paper, we formulate a quantitative model for assessing amplified failure risk. Our analysis shows an unexpected result that the platform risk increases as we become more assured of our design capability; i.e, when a defective design rarely happens, the magnitude of risk amplification becomes much larger. The numerical investigation of a platform planning case sheds light on the importance of risk assessment in determining the level of commonality in designing a platform.

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-minimization 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 as needed, taking into account not only disassembly but also manufacturing, remanufacturing, and holding inventory of remanufacturable parts. This study proposes a linear programming 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.Copyright