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Prof. Sungyong Choi
Hanyang University, Seoul, South Korea

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Research Keywords & Expertise

0 Supply Chain Management
0 Inventory Optimization Modeling
0 Supply Chain Analytics
0 Sustainable and Socially Responsible Operations
0 Healthcare Management Issues in Operations

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Journal article
Published: 30 September 2020 in Journal of Society of Korea Industrial and Systems Engineering
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ACS Style

Donghee Lee; Ministry Of National Defense R.O.K. Army; Byung Yun Bae; Sungyong Choi. An Empirical Study on the Effect of Military Foodservice Satisfaction on Soldiers’ Morale. Journal of Society of Korea Industrial and Systems Engineering 2020, 43, 228 -242.

AMA Style

Donghee Lee, Ministry Of National Defense R.O.K. Army, Byung Yun Bae, Sungyong Choi. An Empirical Study on the Effect of Military Foodservice Satisfaction on Soldiers’ Morale. Journal of Society of Korea Industrial and Systems Engineering. 2020; 43 (3):228-242.

Chicago/Turabian Style

Donghee Lee; Ministry Of National Defense R.O.K. Army; Byung Yun Bae; Sungyong Choi. 2020. "An Empirical Study on the Effect of Military Foodservice Satisfaction on Soldiers’ Morale." Journal of Society of Korea Industrial and Systems Engineering 43, no. 3: 228-242.

Journal article
Published: 01 August 2020 in International Journal of Production Economics
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We consider a supply chain consisting of a supplier and a buyer whose efforts jointly influence carbon emissions per unit of the product. The product demand is affected by the effort levels. The carbon footprint is allocated to the supply chain members by a social planner, and they pay carbon penalties for their allocated emissions. We first examine the social first-best solution and then analyze a no-collaboration scenario, where the supply chain members simultaneously make their own effort decisions under an allocation rule, and two supply chain contracting scenarios: credible buyer and double moral hazard, where the buyer designs and offers a contract to the supplier that specifies an order quantity and a payment scheme contingent on the realized carbon footprint. We find that the social planner may need to over- or under-allocate the emissions to the firms to induce the social first-best effort levels in the no-collaboration scenario. However, the social first-best effort levels can be attained with a simple allocation rule without over- or under-allocation in the credible buyer scenario. For the double moral hazard scenario, where the buyer is not credible to the supplier, the social first-best may not be attainable and there may be a significant loss in the social value of the supply chain.

ACS Style

Jun-Yeon Lee; Sungyong Choi. Supply chain investment and contracting for carbon emissions reduction: A social planner's perspective. International Journal of Production Economics 2020, 231, 107873 .

AMA Style

Jun-Yeon Lee, Sungyong Choi. Supply chain investment and contracting for carbon emissions reduction: A social planner's perspective. International Journal of Production Economics. 2020; 231 ():107873.

Chicago/Turabian Style

Jun-Yeon Lee; Sungyong Choi. 2020. "Supply chain investment and contracting for carbon emissions reduction: A social planner's perspective." International Journal of Production Economics 231, no. : 107873.

Journal article
Published: 22 July 2020 in Journal of Open Innovation: Technology, Market, and Complexity
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The purpose of this paper is to examine the relationship between emotional, managerial, and intellectual competence of team members, which refer to the LDQ (Leadership Development Questionnaire) and impact on project success. (1) Background: Large and complex projects are being conducted in a dynamic business environment. The need for capabilities and managerial aspects of participants of the project for business performance increases. (2) Methods: A questionnaire survey was conducted on 164 project management professionals in various industries from Korea. The structural equation modeling technique was performed to establish the effect of competence of team members on project success factor. (3) Results: The results provided empirical support for the impact of team members’ competencies on project success factor. Moreover, there is no difference in the perception of the impact of team members’ competencies on project success factor, depending on their roles, such as project manager and team member. (4) Results: In this paper, the importance of the competence of team members in accordance with the project manager was presented. The findings of this study suggest the strategic direction of the members at this point when corporate innovation is needed.

ACS Style

Minjeong Oh; Sungyong Choi. The Competence of Project Team Members and Success Factors with Open Innovation. Journal of Open Innovation: Technology, Market, and Complexity 2020, 6, 51 .

AMA Style

Minjeong Oh, Sungyong Choi. The Competence of Project Team Members and Success Factors with Open Innovation. Journal of Open Innovation: Technology, Market, and Complexity. 2020; 6 (3):51.

Chicago/Turabian Style

Minjeong Oh; Sungyong Choi. 2020. "The Competence of Project Team Members and Success Factors with Open Innovation." Journal of Open Innovation: Technology, Market, and Complexity 6, no. 3: 51.

Journal article
Published: 18 March 2019 in Sustainability
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In the era of the fourth industrial revolution, the international community is striving to establish a coordinated system to prevent fatal climate change in a global sense. As a result of such changes in business environments, a new issue, sustainability, has recently presented a paradigm shift and new research opportunity in which the theories and practices in traditional production and operations management are being reinterpreted and reapplied in relation to this emerging issue. Under this research background, we consider an optimal emission-trading problem under a cap-and-trade (CAT) emission regulation when the customers’ demand is given as an arbitrary probability distribution. Such a CAT approach to reduce the amount of emissions is a normative system for the sustainable production of manufacturing firms, which is also closely related to a well-known open innovation in literature of inventory management. Then, we formulate two stochastic inventory optimization models, which can be applied immediately for two famous CAT policies that exist in reality. In particular, our objective is to draw theoretical and practical implications for baseline credit emission regulations, which are innovative and government-led emission regulation policies, with a well-known newsvendor analysis. For our analytical results, we first show that our objective functions are piecewise linear and (quasi)-concave. Thus, it is found that there exists a unique optimal solution to the problem. Second, we successfully obtain the closed-form optimal solutions for the two models considered. Finally, we conduct a sensitivity analysis through a comparative static analysis to examine how the model parameters can affect the optimal solution in each model. All these analytical results and implications are consistent with previous studies in the literature, as well as with our insights for the models.

ACS Style

Sungyong Choi; KyungBae Park; And Sang-Oh Shim. The Optimal Emission Decisions of Sustainable Production with Innovative Baseline Credit Regulations. Sustainability 2019, 11, 1635 .

AMA Style

Sungyong Choi, KyungBae Park, And Sang-Oh Shim. The Optimal Emission Decisions of Sustainable Production with Innovative Baseline Credit Regulations. Sustainability. 2019; 11 (6):1635.

Chicago/Turabian Style

Sungyong Choi; KyungBae Park; And Sang-Oh Shim. 2019. "The Optimal Emission Decisions of Sustainable Production with Innovative Baseline Credit Regulations." Sustainability 11, no. 6: 1635.

Journal article
Published: 26 September 2018 in European Journal of Operational Research
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We study a binomial yield production process using a newsvendor approach by considering the mismatch costs between a given demand and a non-defective yield amount. Using a normal approximation, we reformulate the original discrete and exact model as a continuous and approximate model. We conduct a comparative static analysis of the parameters in the approximate model and derive the monotone properties of the (approximate) optimal solution in the case that the given demand is sufficiently large. The analytical results are all consistent with our insights and are also supported by economic explanations. Our numerical study with sample-based optimization indicates that the approximate model is sufficiently close to the exact model in most real-world examples, with some limiting cases included. Then, a simple and naive solution is found to have significant suboptimality. Finally, the results of a sensitivity analysis of the model parameters are confirmed numerically.

ACS Style

Sungyong Choi; Sumin Jeon; Jinmin Kim; Kwangtae Park. A newsvendor analysis of a binomial yield production process. European Journal of Operational Research 2018, 273, 983 -991.

AMA Style

Sungyong Choi, Sumin Jeon, Jinmin Kim, Kwangtae Park. A newsvendor analysis of a binomial yield production process. European Journal of Operational Research. 2018; 273 (3):983-991.

Chicago/Turabian Style

Sungyong Choi; Sumin Jeon; Jinmin Kim; Kwangtae Park. 2018. "A newsvendor analysis of a binomial yield production process." European Journal of Operational Research 273, no. 3: 983-991.

Journal article
Published: 21 September 2018 in Journal of Open Innovation: Technology, Market, and Complexity
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This research addresses a specific issue in the field of operation scheduling. Even though there are lots of researches on the field of planning and scheduling, a specific scheduling problem is introduced here. We focus on the operation scheduling requirements that the Fourth Industrial Revolution has brought currently. From the point of view of open innovation, operation scheduling is known as the one that is using the Internet of Things, Cloud Computing, Big Data, and Mobile technology. To build proper operation systems under the Fourth Industrial Revolution, it is very essential to devise effective and efficient scheduling methodology to improve product quality, customer delivery, manufacturing flexibility, cost saving, and market competence. A scheduling problem on designated parallel equipments, where some equipments are grouped according to the recipe of lots, is considered. This implies that a lot associated with a specific recipe is preferred to be processed on an equipment among predetermined (designated) ones regardless of parallel ones. A setup operation occurs between different recipes of lots. In order to minimize completion time of the last lot, a scheduling algorithm is proposed. We conducted a simulation study with randomly generated problems, and the proposed algorithm has shown desirable and better performance that can be applied in real-time scheduling.

ACS Style

Sang-Oh Shim; KyungBae Park; Sungyong Choi. Sustainable Production Scheduling in Open Innovation Perspective under the Fourth Industrial Revolution. Journal of Open Innovation: Technology, Market, and Complexity 2018, 4, 42 .

AMA Style

Sang-Oh Shim, KyungBae Park, Sungyong Choi. Sustainable Production Scheduling in Open Innovation Perspective under the Fourth Industrial Revolution. Journal of Open Innovation: Technology, Market, and Complexity. 2018; 4 (4):42.

Chicago/Turabian Style

Sang-Oh Shim; KyungBae Park; Sungyong Choi. 2018. "Sustainable Production Scheduling in Open Innovation Perspective under the Fourth Industrial Revolution." Journal of Open Innovation: Technology, Market, and Complexity 4, no. 4: 42.

Journal article
Published: 22 June 2018 in Sustainability
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This study aims to provide an optimization model for operational efficiency in individual firms with cap-and-trade carbon emissions regulation. In addition, this study assumes that customers’ demand takes a probability distribution. Under this circumstance, our intention is to draw theoretical and policy implications for carbon emissions regulation by setting and analyzing newsvendor models in which the decision maker is loss-averse for her risk preference. Then, we formulate two loss-averse newsvendor models where we use a “kinked” piecewise linear and concave utility function. More specifically, we show that our objective functions are concave to derive the existence and uniqueness of the optimal solution. After then, through a comparative static analysis, we conduct a sensitivity analysis of how the model parameters affect the optimal solution. Then, the analytical results can be summarized as follows. First, in a lost-sale model, loss aversion significantly affects the optimal policy of newsvendors’ decision-making with cap-and-trade regulations. Second, in a stockout penalty cost model, the inclusion of cap-and-trade regulation terms and shortage penalty costs adds more structural complexity in the optimal solution. Thus, the directions of the impacts are mixed and the impacts on the optimal solutions are not monotone, especially with cap-and-trade terms. All these analytical results show big differences between the existing risk-neutral and our loss-averse models, which are confirmed by numerical experiments.

ACS Style

Sungyong Choi. A Loss-Averse Newsvendor with Cap-and-Trade Carbon Emissions Regulation. Sustainability 2018, 10, 2126 .

AMA Style

Sungyong Choi. A Loss-Averse Newsvendor with Cap-and-Trade Carbon Emissions Regulation. Sustainability. 2018; 10 (7):2126.

Chicago/Turabian Style

Sungyong Choi. 2018. "A Loss-Averse Newsvendor with Cap-and-Trade Carbon Emissions Regulation." Sustainability 10, no. 7: 2126.

Journal article
Published: 03 January 2018 in Journal of Open Innovation: Technology, Market, and Complexity
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In the era of Industry 4.0, firms are facing with greater uncertainty. Accordingly, it is important to select quality risk measures to analyze newsvendor problems under risk. Then, open innovation can be a good remedial option for such risk-averse newsvendors because open innovation can offset the profit losses from risk aversion by sharing revenues in supply chains. To find such risk measures in newsvendor problems, we review various risk measures of risk-averse inventory models and existing articles in inventory management literature. Then we provide a logical reasoning and axiomatic framework to evaluate validity of each risk measure in newsvendor problems - consistency to the four axioms in coherent risk measures. In this framework, the underlying assumptions and managerial insights to the newsvendor problems are examined for each risk measure. Consequently, exponential utility function and coherent measures of risk are selected as two plausible risk measures to analyze multi-product risk-averse newsvendor models.

ACS Style

Sungyong Choi; KyungBae Park; Sang-Oh Shim. Comparing validity of risk measures on newsvendor models in open innovation perspective. Journal of Open Innovation: Technology, Market, and Complexity 2018, 4, 1 -12.

AMA Style

Sungyong Choi, KyungBae Park, Sang-Oh Shim. Comparing validity of risk measures on newsvendor models in open innovation perspective. Journal of Open Innovation: Technology, Market, and Complexity. 2018; 4 (1):1-12.

Chicago/Turabian Style

Sungyong Choi; KyungBae Park; Sang-Oh Shim. 2018. "Comparing validity of risk measures on newsvendor models in open innovation perspective." Journal of Open Innovation: Technology, Market, and Complexity 4, no. 1: 1-12.

Journal article
Published: 05 December 2017 in Sustainability
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Scheduling problems for the sustainability of manufacturing firms in the era of the fourth industrial revolution is addressed in this research. In terms of open innovation, innovative production scheduling can be defined as scheduling using big data, cyber-physical systems, internet of things, cloud computing, mobile network, and so on. In this environment, one of the most important things is to develop an innovative scheduling algorithm for the sustainability of manufacturing firms. In this research, a flexible flowshop scheduling problem is considered with the properties of sequence-dependent setup and different process plans for jobs. In a flexible flowshop, there are serial workstations with multiple pieces of equipment that are able to process multiple lots simultaneously. Since the scheduling in this workshop is known to be extremely difficult, it is important to devise an efficient and effective scheduling algorithm. In this research, a heuristic algorithm is proposed based on a few dispatching rules and economic lot size model with the objective of minimizing total tardiness of orders. For the purposes of performance evaluation, a simulation study is conducted on randomly generated problem instances. The results imply that our proposed method outperforms the existing ones, and greatly enhances the sustainability of manufacturing firms.

ACS Style

Sang-Oh Shim; KyungBae Park; Sungyong Choi. Innovative Production Scheduling with Customer Satisfaction Based Measurement for the Sustainability of Manufacturing Firms. Sustainability 2017, 9, 2249 .

AMA Style

Sang-Oh Shim, KyungBae Park, Sungyong Choi. Innovative Production Scheduling with Customer Satisfaction Based Measurement for the Sustainability of Manufacturing Firms. Sustainability. 2017; 9 (12):2249.

Chicago/Turabian Style

Sang-Oh Shim; KyungBae Park; Sungyong Choi. 2017. "Innovative Production Scheduling with Customer Satisfaction Based Measurement for the Sustainability of Manufacturing Firms." Sustainability 9, no. 12: 2249.

Journal article
Published: 01 March 2017 in Advanced Science Letters
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We suggest a mixed integer programming model for solving a scheduling problem in a single machine shop. The scheduling problem considered here addresses two urgencies of jobs, i.e., urgent jobs and normal jobs, in which can be occurred in the real IT manufacturing firms, to minimize total tardiness for urgent ones and total completion time of normal ones. Two linear mathematical formulations by using time indexed methods are proposed for this problem and these are compared with the existing algorithms used in the real situation. Computational experiments with randomly generated instances are conducted and results of the experiments show that proposed time indexed formulation can obtain optimal solutions in shorter time than another mathematical formulation.

ACS Style

Bongjoo Jeong; Sang-Oh Shim; Sungyong Choi. Mathematical Programming Model for a Single Machine Scheduling in an IT Manufacturing Firms. Advanced Science Letters 2017, 23, 1705 -1708.

AMA Style

Bongjoo Jeong, Sang-Oh Shim, Sungyong Choi. Mathematical Programming Model for a Single Machine Scheduling in an IT Manufacturing Firms. Advanced Science Letters. 2017; 23 (3):1705-1708.

Chicago/Turabian Style

Bongjoo Jeong; Sang-Oh Shim; Sungyong Choi. 2017. "Mathematical Programming Model for a Single Machine Scheduling in an IT Manufacturing Firms." Advanced Science Letters 23, no. 3: 1705-1708.

Research article
Published: 26 August 2015 in Mathematical Problems in Engineering
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We study a few dynamic risk-averse inventory models using additive utility functions. We add Markovian behavior of purchasing costs in our models. Such Markovian purchasing costs can reflect a market situation in a global supply chain such as fluctuations at exchange rates or the existence of product spot markets. We provide our problem formulations with finite and infinite MDP (Markovian Decision Process) problems. For finite time models, we first prove (joint) concavity of the model for each state and obtain a (modified) base-stock optimal policy. Then, we conduct comparative static analysis for model parameters and derive monotone properties to the optimal solutions. For infinite time models, we show the existence of stationary base-stock optimal policies and the inheritance of the monotone properties proven at our finite time models.

ACS Style

Sungyong Choi; KyungBae Park. A Risk-Averse Inventory Model with Markovian Purchasing Costs. Mathematical Problems in Engineering 2015, 2015, 1 -9.

AMA Style

Sungyong Choi, KyungBae Park. A Risk-Averse Inventory Model with Markovian Purchasing Costs. Mathematical Problems in Engineering. 2015; 2015 ():1-9.

Chicago/Turabian Style

Sungyong Choi; KyungBae Park. 2015. "A Risk-Averse Inventory Model with Markovian Purchasing Costs." Mathematical Problems in Engineering 2015, no. : 1-9.

Book chapter
Published: 11 May 2012 in International Series in Operations Research & Management Science
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I consider a multi-product risk-averse newsvendor under the law-invariant coherent measures of risk. I first establish a few fundamental properties of the model regarding the convexity of the problem and the symmetry of the solution, and study the impacts of risk aversion and shift in mean demand to the optimal solution with independent demands. Specifically, I show that for identical products with independent demands, increased risk aversion leads to decreased orders. For a large but finite number of heterogenous products with independent demands, I derive closed-form approximations for the optimal order quantities. The approximations are as simple to compute as the classical risk-neutral solutions. I also show that the risk-neutral solution is asymptotically optimal as the number of products tends to be infinity, and thus risk aversion has no impact in the limit. For a risk-averse newsvendor with dependent demands, I show that positively (negatively) dependent demands lead to a lower (higher) optimal order quantities than independent demands. Using a numerical study, I examine the convergence rates of the approximations and develop additional insights on the interplay between dependent demands and risk aversion.

ACS Style

Sungyong Choi. A Multi-item Risk-Averse Newsvendor with Law Invariant Coherent Measures of Risk. International Series in Operations Research & Management Science 2012, 176, 41 -79.

AMA Style

Sungyong Choi. A Multi-item Risk-Averse Newsvendor with Law Invariant Coherent Measures of Risk. International Series in Operations Research & Management Science. 2012; 176 ():41-79.

Chicago/Turabian Style

Sungyong Choi. 2012. "A Multi-item Risk-Averse Newsvendor with Law Invariant Coherent Measures of Risk." International Series in Operations Research & Management Science 176, no. : 41-79.

Journal article
Published: 01 October 2011 in European Journal of Operational Research
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ACS Style

Sungyong Choi; Andrzej Ruszczyński. A multi-product risk-averse newsvendor with exponential utility function. European Journal of Operational Research 2011, 214, 78 -84.

AMA Style

Sungyong Choi, Andrzej Ruszczyński. A multi-product risk-averse newsvendor with exponential utility function. European Journal of Operational Research. 2011; 214 (1):78-84.

Chicago/Turabian Style

Sungyong Choi; Andrzej Ruszczyński. 2011. "A multi-product risk-averse newsvendor with exponential utility function." European Journal of Operational Research 214, no. 1: 78-84.

Journal article
Published: 01 April 2011 in Operations Research
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ACS Style

Sungyong Choi; Andrzej Ruszczyński; Yao Zhao. A Multiproduct Risk-Averse Newsvendor with Law-Invariant Coherent Measures of Risk. Operations Research 2011, 59, 346 -364.

AMA Style

Sungyong Choi, Andrzej Ruszczyński, Yao Zhao. A Multiproduct Risk-Averse Newsvendor with Law-Invariant Coherent Measures of Risk. Operations Research. 2011; 59 (2):346-364.

Chicago/Turabian Style

Sungyong Choi; Andrzej Ruszczyński; Yao Zhao. 2011. "A Multiproduct Risk-Averse Newsvendor with Law-Invariant Coherent Measures of Risk." Operations Research 59, no. 2: 346-364.

Conference paper
Published: 01 May 2010 in 2010 Eleventh International Conference on Mobile Data Management
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The concept of location k-anonymity has been proposed to address the privacy issue of location based services (LBS). Under this notion of anonymity, the adversary only has the knowledge that the LBS request originates from a region containing at least k people, and therefore cannot individually distinguish the requestor. However, new types of LBS services such as continuous nearest neighbor searches require the knowledge of the user's trajectory, which can lead to a privacy breach. The longer the adversary can track the user's trajectory, the stronger the possibility that the user's sensitive information is revealed. To alleviate this problem, we propose algorithms to optimally partition a continuous request into multiple LBS requests with shorter trajectories. This results in increased privacy due to the unlinking of different requests over time and has the added benefit of improving the overall quality of service since the anonymized regions are now smaller. Our experimental results show that significant privacy and QoS benefits can be achieved with nominal computational overhead.

ACS Style

Heechang Shin; Jaideep Vaidya; Vijayalakshmi Atluri; Sungyong Choi. Ensuring Privacy and Security for LBS through Trajectory Partitioning. 2010 Eleventh International Conference on Mobile Data Management 2010, 224 -226.

AMA Style

Heechang Shin, Jaideep Vaidya, Vijayalakshmi Atluri, Sungyong Choi. Ensuring Privacy and Security for LBS through Trajectory Partitioning. 2010 Eleventh International Conference on Mobile Data Management. 2010; ():224-226.

Chicago/Turabian Style

Heechang Shin; Jaideep Vaidya; Vijayalakshmi Atluri; Sungyong Choi. 2010. "Ensuring Privacy and Security for LBS through Trajectory Partitioning." 2010 Eleventh International Conference on Mobile Data Management , no. : 224-226.

Short communication
Published: 31 January 2008 in Operations Research Letters
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For general law invariant coherent measures of risk, we derive an equivalent representation of a risk-averse newsvendor problem as a mean-risk model. We prove that the higher the weight of the risk functional, the smaller the order quantity. Our theoretical results are confirmed by sample-based optimization.

ACS Style

Sungyong Choi; Andrzej Ruszczyński. A risk-averse newsvendor with law invariant coherent measures of risk. Operations Research Letters 2008, 36, 77 -82.

AMA Style

Sungyong Choi, Andrzej Ruszczyński. A risk-averse newsvendor with law invariant coherent measures of risk. Operations Research Letters. 2008; 36 (1):77-82.

Chicago/Turabian Style

Sungyong Choi; Andrzej Ruszczyński. 2008. "A risk-averse newsvendor with law invariant coherent measures of risk." Operations Research Letters 36, no. 1: 77-82.