Risk Minimization in Resource Allocation under Limited Construction Budgets = 한정된 건설 예산에서 자원분배 리스크 최소화

국문 초록 (Abstract)

건설공사는 한정된 예산을 가지고 수행된다. 따라서 관리자는 프로젝트 리스크를 최소화하면서 주어진 예산을 적절하게 공종별로 분배해야 한다. 이를 위하여 본 논문에서는 투자이론 중 하나인 마코위츠의 포트폴리오 분산이론을 건설 사업비 분야에 적용시켰다.
포트폴리오 분산이론을 사용하면 개별 공종들의 합리적인 자원분배를 위해서 리스크 분배 가중치를 계산할 수 있다. 계산된 리스크 분배 가중치를 사용하면 전체 리스크(분산)를 최소화하는 규칙으로 자원분배가 이루어진다. 이러한 포트폴리오 자원분배 규칙을 가설로 세우고 건설 전문가의 자원분배 행동방식이 설정한 가설과의 일치여부를 확인하기 위해 설문조사가 실시되었다. 그 결과 건설 전문가의 자원분배 행동방식이 가설에 수렴한다는 사실을 검증할 수 있었다. 검증된 포트폴리오 자원분배에 대한 규칙을 활용하여 최종적으로 합리적인 예산분배 모델을 개발하였다. 제안된 모델에서는 실적 데이터의 정확한 분석을 위하여 확률분포 모형의 적합도 시험을 실시하여 공종별 적절한 확률분포를 결정하였으며, 공종 상호간 작용하는 상관관계도 고려대상에 포함시켰다.
본 논문은 공무 담당자가 건설사업 초기단계에서 실행예산 및 입찰을 위해 한정된 건설자원을 최대한 활용할 수 있는 합리적인 예산분배 모델을 제안하였다. 그리고 사례를 통하여 제안된 모델을 사용하면 최적의 리스크를 가지는 건설 공사비로 조정할 수 있음을 보여주었다.

다국어 초록 (Multilingual Abstract)

The construction operation is usually executed under limited resource. Given the limitation, the construction manager should allocate resource in a fashion to minimize the risk inherent in the dynamic construction work items. This paper investigated Markowitz's Portfolio theory to minimize the risk in allocating construction budget.
A Portfolio diversification model can systematically allocate resource using optimal weight for each work item to minimize overall risk. Hypotheses have been set up by Portfolio theory's allocation method to understand the rational behavior of experts in planning construction resource, and tested to proof the rationality in construction cost through a questionnaire. As a result, behavior of Portfolio diversification and experts was the same in allocating construction resource. RRAM (Rational Resource Allocation Model) which is based on the rationality rules of Portfolio diversification in resource distribution was developed in order to minimize the overall risk. The model was conducted goodness of fit test for appropriate distribution and considered correlation between work items to forecast accurate construction costs using historical cost
The RRAM was intended to minimize the overall risk shown in resource allocation. In an example study, the model demonstrated that the budget of construction work items can be adjusted to estimate the construction cost to attain the minimum level of operational risk.

목차 (Table of Contents)

• 1. INTRODUCTION 1
• 1.1 Background 1
• 1.2 Problems and Needs 2
• 1.3 Research Objectives 4
• 1.4 Research Procedure 5
• 1.5 Research Scope 6
• 1.6 Organization of the Dissertation 7
• 2. LITERATURE REVIEW 8
• 2.1 Estimating in Construction 8
• 2.1.1 The Cycle of Estimating 8
• 2.1.2 Conceptual Estimates 11
• 2.2 Portfolio Theory 13
• 2.3 Resource Allocation 14
• 2.3.1 Resource Allocation in Costs 14
• 2.3.2 Resource Allocation in Scheduling 16
• 2.4 Correlation and Distribution 17
• 2.5 Historical Cost Data 20
• 2.5.1 Historical Cost Data in Korea 20
• 2.5.2 Historical Cost Data in Oversea 23
• 3. PORTFOLIO DIVERSIFICATION 27
• 3.1 Portfolio Theory 27
• 3.1.1 Return and Risk in Portfolio Theory 27
• 3.1.2 Covariance 29
• 3.1.3 Coefficient of Correlation 30
• 3.1.4 Degree of Dispersion (DoD) 32
• 3.2 Risk Reduction 35
• 3.2.1 Risk Allocation in Portfolio Theory 35
• 3.2.2 Unsystematic Risk and Systematic Risk in Construction 35
• 3.2.3 The Effect of Diversification in Portfolio 36
• 3.3 Relationship between Correlation and Diversification 38
• 3.3.1 Correlation Type of Two Securities 38
• 3.3.2 Diversification of Two Securities 39
• 3.4 Minimum Variance (Risk) Portfolio with N Securities 43
• 3.4.1 Efficient Frontier 43
• 3.4.2 Dominance Principle 44
• 4. SAMPLE DATA SET OF CONSTRUCTION WORK ITEMS 46
• 4.1 Introduction of Historical Cost Data 46
• 4.2 Adjusted Time using Historical Cost Index 48
• 4.3 Distributions in Construction 50
• 4.3.1 Types of Probability Distribution 50
• 4.3.2 Goodness of Fit Test for Distribution 51
• 4.3.3 Choice of Distributions 52
• 4.4 Correlation in Construction 53
• 4.5 Probability Distributions 55
• 4.5.1 Arithmetic Method 55
• 4.5.2 Monte Carlo Simulation method 56
• 4.6 Data Set of Elementary Schools 58
• 4.7 Impact of Correlation and Choice of Distribution 59
• 4.8 Quantity Takeoff 61
• 4.9 Estimate of Cost Ranges 63
• 5. RISK MINIMIZATION IN RESOURCE ALLOCATION 66
• 5.1. Rationality in Resource Allocation 66
• 5.1.1 Research Hypothesis 67
• 5.1.2 Organization of a Questionnaire Form 68
• 5.1.3 Data Analysis and Discussion 70
• 5.1.4 The Hypotheses Test and Portfolio Theory 71
• 5.2 Application of Portfolio Diversification 73
• 5.3 Adjusted Weights 74
• 5.4 Adjusted Cost at Minimum Variance (at Minimum Risk) 77
• 5.5 Minimum Risk with Zero Correlation 78
• 5.5.1 Minimum Level of Uncertainty (ρ=0) 78
• 5.5.2 Efficient Frontier Line of Construction Cost (ρ=0) 82
• 5.6 Minimum Risk with Actual Correlation 84
• 5.6.1 Minimum Level of Uncertainty (ρ=actual) 84
• 5.6.2 Efficient Frontier Line of Construction Cost (ρ=actual) 86
• 5.7 Rationality in Cost Diversification 88
• 6. CONCLUSIONS 91
• 6.1 Summary 91
• 6.2 Contributions 92
• 6.3 Conclusions 94
• 6.4 Recommendations 96
• REFERENCES 98
• APPENDIXES 107
• Appendix I: Questionnaire 108
• Appendix II: Typical Size Gross Sq. Ft. 109
• Abstract 110