Changhyun Kwon Quarterly

a working paper series in operations research

The CK Quarterly introduces working papers from Dr. Changhyun Kwon and STOM Lab in each season, four times a year. Issues will cover various topics in operations research, optimization, transportation systems, and service operations. This series started in Winter 2014. Dr. Kwon is currently an associate professor in the Department of Industrial and Management Systems Engineering at the University of South Florida.

계간 권창현 | 季刊 權昶賢


The web page design was adopted from git - the simple guide. This quarterly project is inspired by a Korean musician Yoon Jong Shin for his Monthly Project.

CK Quarterly – Winter 2019

Optimizing the Relocation Operations of Free-Floating Electric Vehicle Sharing Systems

with Zulqarnain Haider, Hadi Charkhgard, Sang Won Kim

Free-floating electric vehicle (EV) sharing systems require frequent relocations of EVs. Such operations require drivers to move EVs and shuttles to move drivers around. How to route both shuttles and drivers? How many shuttles and drivers are necessary? This paper provides insights on these questions.

PDF Download

CK Quarterly – Fall 2019

Pessimistic Evasive Flow Capturing Problems

with Aigerim Bogyrbayeva

Will unlawful friegh truck drivers choose the shortest path always? If not, how much are they willing to deviate from the shrotest path to avoid weigh-in-motion sensors? How to model such behavior within a bilevel programming problem?

PDF Download

CK Quarterly – Summer 2019

Exact Robust Solutions for the Combined Facility Location and Network Design Problem in Hazardous Materials Transportation

with Xufei Liu

Where to locate hazmat facilities and how to control hazmat truck traffic? A joint decision-making approach under uncertainty.

PDF Download

CK Quarterly – Spring 2019

Path-Based Approaches to Robust Network Design Problems Considering Boundedly Rational Network Users

with Longsheng Sun and Mark Karwan

When network users are satisficing decision makers, how to design a road network? A path-based approach is considered to design hazmat roadban policies.

PDF Download

CK Quarterly – Winter 2018

Sensitivity of Wardrop Equilibria: Revisited

with Mahdi Takalloo

When the travel demand increases by the factor of $(1+\epsilon)$, how much will the price of anarchy increase? This short paper shows that it is bounded by $(1+\epsilon)^p$, when the latency functions are degree of $p$.

PDF Download

CK Quarterly – Fall 2018

Spectral Risk Measure Minimization in Hazardous Materials Transportation

with Liu Su, Longsheng Sun, and Mark Karwan

For risk-averse routing of hazmat, how can we balance between the expected risk and the quantiles? This paper attempts to generalize various risk measures in hazmat transportation using the spectral risk measure.

PDF Download

CK Quarterly – Summer 2018

Risk-Averse Network Design with Behavioral Conditional Value-at-Risk for Hazardous Materials Transportation

with Liu Su

If the route choice of hazmat carriers is probabilistic, how can we protect the urban road network from hazmat accidents?

PDF Download

CK Quarterly – Spring 2018

Inventory Rebalancing through Pricing in Public Bike Sharing Systems

with Zulqarnain Haider, Alexander Nikolaev, and Jee Eun Kang

In any bike sharing system, manual rebalancing---usually by trucks or other vehicles---is a challenging issue. This paper proposes a pricing scheme to achieve "automatic" rebalancing, at least partially.

PDF Download

CK Quarterly – Winter 2017

A Robust Optimization Approach for Solving Problems in Conservation Planning

with Zulqarnain Haider and Hadi Charkhgard

Dealing with data uncertainty in conservation planning

PDF Download

CK Quarterly – Fall 2017

On the Price of Satisficing in Network User Equilibria

with Mahdi Takalloo

Comparing the performances of (perfectly rational) user equilibrium and satisficing user equilibrium

PDF Download

CK Quarterly – Summer 2017

Julia Package

Are you solving a complementarity problem or a mathematical program with equilibrium constraints (MPEC)? Here is a Julia package for solving problems involving complementarity.


CK Quarterly – Spring 2017

Equitable Distribution of Recharging Stations for Electric Vehicles

with Byung Do Chung and Sungjae Park

When we locate new recharging stations, how can we consider regional equity?

PDF Download

CK Quarterly – Winter 2016

Time-Dependent Hazardous-materials Network Design Problem

with Tolou Esfandeh and Rajan Batta

Curfew design to make road network safe from hazmat accidents

PDF Download

CK Quarterly – Fall 2016

Generalized Bounded Rationality and Robust Multi-Commodity Network Design

with Longsheng Sun and Mark Karwan

Optimizing under imprecise perception is equivalent to satisficing under precise perception.

PDF Download

CK Quarterly – Summer 2016

Julia Programming for Operations Research: A Primer on Computing

Julia is a computer language for scientific computing. This book introduces Julia programming for common tasks in operations research. This book is mainly targetted to first-year graduate students in operations research and related fields, but will also be suitable for advanced undergraduate students and practitioners.

Online Book Link

CK Quarterly – Spring 2016

Multi-Period Capacitated Recharging Location Planning for Electric Vehicles

with Anpeng Zhang and Jee Eun Kang

Where to locate recharging stations for electirc vehicles, in what order?

PDF Download

CK Quarterly – Winter 2015

Impact of Dual-Toll Pricing in Hazmat Transportation considering Stochastic Driver Preferences

with Tolou Esfandeh, Masoumeh Taslimi, and Rajan Batta

When drivers' preferences over tolls and time are probabilistic, how should we charge tolls for regulating both hazmat truck drivers and other regular drivers to mitigate the risk from hazmat accidents?

PDF Download

CK Quarterly – Fall 2015

Incorporating Driver Behaviors in Network Design Problems: Challenges and Opportunities

with Longsheng Sun and Mark Karwan

When we design road networks, we need to predict drivers' new behavior. How should we model such prediction? This paper provides a comprehensive review.

PDF Download

CK Quarterly – Summer 2015

A Comprehensive Modeling Framework for Hazmat Network Design, Hazmat Response Team Location, and Equity of Risk

with Masoumeh Taslimi and Rajan Batta

If we allow more roads for hazmat, can we make a safer road network? Should we change the location of hazmat response units accordingly? Would some residents be unhappy with that change? This paper suggests a comprehensive modeling framework to answer these questions.

PDF Download

CK Quarterly – Spring 2015

Regulating Hazardous Materials Transportation by Dual Toll Pricing

with Tolou Esfandeh and Rajan Batta

This paper investigates how we can make the road network safer by regulating hazardous materials transportation via dual toll pricing. The core idea is to charge separate tolls for regular vehicles and hazmat trucks. Computational methods are proposed.

PDF Download

Julia Packages

The Julia Langugage is a recently developed programming language for numerical computations. RobustShortestPath.jl is a package that finds robust shortest paths when travel cost is subject to uncertainty. TrafficAssignment.jl finds traffic user equilibrium for congested road networks.

RobustShortestPath.jl TrafficAssignment.jl

CK Quarterly – Winter 2014

Worst-case Conditional Value-at-Risk Minimization for Hazardous Materials Transportation

with Iakovos Toumazis

How should we determine a safe route for transporting hazardous materials such as explosive and corrosive chemicals? This paper questions existing routing methods in hazmat transportation and proposes a robust and risk-averse routing method.

PDF Download

Robust Hazmat Network Design Problems Considering Risk Uncertainty

with Longsheng Sun and Mark Karwan

Most research in hazmat transportation ignore uncertainty in consequences from a hazmat accident. To design a safe road network, this paper considers uncertainty in accident consequences and develops a computational method based on Lagrangian-relaxation.

PDF Download