Development of Dispatching Strategy for Inbound and Outbound Trucks in Cross Docking System

Wooyeon Yu,Pius J. Egbelu 대한안전경영과학회 2013 대한안전경영과학회지 Vol.15 No.2

Storm Sudden Commencements Without Interplanetary Shocks

Wooyeon Park,Jeongwoo Lee,Yu Yi,Nicholas Ssessanga,Suyeon Oh 한국우주과학회 2015 Journal of Astronomy and Space Sciences Vol.32 No.3

Storm sudden commencements (SSCs) occur due to a rapid compression of the Earth's magnetic field. This is generally believed to be caused by interplanetary (IP) shocks, but with exceptions. In this paper we explore possible causes of SSCs other than IP shocks through a statistical study of geomagnetic storms using SYM-H data provided by the World Data Center for Geomagnetism – Kyoto and by applying a superposed epoch analysis to simultaneous solar wind parameters obtained with the Advanced Composition Explorer (ACE) satellite. We select a total of 274 geomagnetic storms with minimum SYM-H of less than –30nT during 1998-2008 and regard them as SSCs if SYM-H increases by more than 10 nT over 10 minutes. Under this criterion, we found 103 geomagnetic storms with both SSC and IP shocks and 28 storms with SSC not associated with IP shocks. Storms in the former group share the property that the strength of the interplanetary magnetic field (IMF), proton density and proton velocity increase together with SYM-H, implying the action of IP shocks. During the storms in the latter group, only the proton density rises with SYM-H. We find that the density increase is associated with either high speed streams (HSSs) or interplanetary coronal mass ejections (ICMEs), and suggest that HSSs and ICMEs may be alternative contributors to SSCs.

Design and Implementation of Robotic Parcel-Sorting Systems

Wooyeon Yu,Jaekyung Yang,Hoon Jung,Myoungjin Choi 한국산학기술학회 2014 SmartCR Vol.4 No.2

With the recent increase in e-business, post offices or door-to-door parcel delivery companies have witnessed a corresponding increase in the number of parcels handled. Most of these parcels are still being handled manually, which results in an increased workload for employees and lowers efficiency. Korea Post has considered a smart-robot manipulation system to automate parcel-sorting procedures that remain manual. This study examined parcel-sorting methods using a robotic system with the aim of reducing the workloads of deliverymen and enhancing parcel-sorting efficiency. We developed a methodology for the design of a robotic parcel-sorting system, and the system was then tested and implemented in accordance with this methodology. The results of this study are expected to reduce parcel workloads of deliverymen and improve parcel-sorting efficiency.

Storm Sudden Commencements Without Interplanetary Shocks

Park, Wooyeon,Lee, Jeongwoo,Yi, Yu,Ssessanga, Nicholas,Oh, Suyeon The Korean Space Science Society 2015 Journal of Astronomy and Space Sciences Vol.32 No.3

Storm sudden commencements (SSCs) occur due to a rapid compression of the Earth's magnetic field. This is generally believed to be caused by interplanetary (IP) shocks, but with exceptions. In this paper we explore possible causes of SSCs other than IP shocks through a statistical study of geomagnetic storms using SYM-H data provided by the World Data Center for Geomagnetism - Kyoto and by applying a superposed epoch analysis to simultaneous solar wind parameters obtained with the Advanced Composition Explorer (ACE) satellite. We select a total of 274 geomagnetic storms with minimum SYM-H of less than -30nT during 1998-2008 and regard them as SSCs if SYM-H increases by more than 10 nT over 10 minutes. Under this criterion, we found 103 geomagnetic storms with both SSC and IP shocks and 28 storms with SSC not associated with IP shocks. Storms in the former group share the property that the strength of the interplanetary magnetic field (IMF), proton density and proton velocity increase together with SYM-H, implying the action of IP shocks. During the storms in the latter group, only the proton density rises with SYM-H. We find that the density increase is associated with either high speed streams (HSSs) or interplanetary coronal mass ejections (ICMEs), and suggest that HSSs and ICMEs may be alternative contributors to SSCs.

Asymmetric cosmic ray modulation of Forbush decreases related to the propagation direction of ICMEs

Suyeon Oh,Wooyeon Park,Yu Yi 한국천문학회 2013 天文學會報 Vol.38 No.2

Simulation of One-way Carsharing Systems : Operating Parameters and Relocation Policy Analysis

SeJoon Park,Wooyeon Yu,Yunsun Park 한국산업경영시스템학회 2019 한국산업경영시스템학회지 Vol.42 No.3

The concept of carsharing involves sharing a small number of reserved cars to be used individually by a larger number of people as required. This study examines the operating parameters of one-way carsharing systems in order to determine the appropriate operating conditions that minimizes the lost sales rate. Five operating parameters are tested in this study: the number of stations, the average number of vehicles per station, the rate of one-way trip, the average number of staffs per station, and the relocation policy. The performance of round-trip carsharing systems is also compared to that of one-way carsharing systems. A simulation model is developed and simulations are performed to determine the appropriate combination of operating parameter and levels. The simulation results show that the average number of vehicles per station is the most critical parameter. Other key findings obtained from this research are as follows. First, applying the appropriate relocation policy to one-way carsharing systems can allow more customers to rent vehicles than the traditional round-trip carsharing systems. Second, the appropriate relocation policy should be selected based on the average number of vehicles per station in order to minimize the lost sales rate. Third, the number of stations does not affect the lost sales rate. This study findings will provide tools to understand impact of the carsharing system parameters on the efficiency of the carsharing operations.

A Web-based Analysis and Design System for Automated Material Handling Equipment Applications

Chiwoon Cho,Wooyeon Yu,Jaekyung Yang 대한산업공학회 2005 산업공학 Vol.18 No.4

시뮬레이션을 활용한 편도 카쉐어링 시스템의 최적 운영 조건 및 차량 재배치 알고리즘에 대한 연구

박세준(SeJoon Park),유우연(Wooyeon Yu),박윤선(Yunsun Park) 한국산업경영시스템학회 2019 한국산업경영시스템학회지 Vol.42 No.3

The concept of carsharing involves sharing a small number of reserved cars to be used individually by a larger number of people as required. This study examines the operating parameters of one-way carsharing systems in order to determine the appropriate operating conditions that minimizes the lost sales rate. Five operating parameters are tested in this study: the number of stations, the average number of vehicles per station, the rate of one-way trip, the average number of staffs per station, and the relocation policy. The performance of round-trip carsharing systems is also compared to that of one-way carsharing systems. A simulation model is developed and simulations are performed to determine the appropriate combination of operating parameter and levels. The simulation results show that the average number of vehicles per station is the most critical parameter. Other key findings obtained from this research are as follows. First, applying the appropriate relocation policy to one-way carsharing systems can allow more customers to rent vehicles than the traditional round-trip carsharing systems. Second, the appropriate relocation policy should be selected based on the average number of vehicles per station in order to minimize the lost sales rate. Third, the number of stations does not affect the lost sales rate. This study findings will provide tools to understand impact of the carsharing system parameters on the efficiency of the carsharing operations.

Feature Selection Applied to Recommender Systems for Reverse Logistics Internet Auction : 역 물류 환경 인터넷 경매를 위한 요소 선택 응용 추천 시스템

양재경(Jaekyung Yang),유우연(Wooyeon Yu) 한국산업경영시스템학회 2006 한국산업경영시스템학회 학술대회 Vol.2006 No.춘계

다양한 데이터 마이닝 기법들의 발전과 더불어, 속성 (Feature 또는 Attribute) 의 범위 (Dimension) 를 줄이기 위해 많은 요소 선택 방법이 개발되었다. 이는 확장성 (Scalability) 을 향상시킬 수 있고 학습 모델 (Learning Model)을 더욱 쉽게 해석할 수 있도록 한다. 이 논문에서는 네스티드 분할 (Nested Partition, 이하 NP) 을 이용한 새로운 최적화 기반 속성 선택 방법을 NP 기본 구조와 다양한 실험 문제의 수치적 결과들과 함께 제시하여 어떻게 NP의 최적화 구조가 속성 선택 과정에 기여를 하고 있는지 보여준다. 그리고 이 새로운 지능적인 분할 방법이 어떻게 매우 효율적인 분할을 수행하는지를 제시한다. 이 새로운 속성 선택 방법은 필터 (Filter) 방법과 래퍼 (Wrapper) 방법 두 가지로 구현될 수 있다. 사례 연구로서, B2B e-비즈니스 시스템에서 효과적으로 사용될 수 있는 추천 시스템(Recommender System) 을 제안하였다. 이 추천 시스템은 분류 기법 (Classification Rule) 과 제시된 NP 기반 요소 선택 방법을 사용하고 있다. 이 추천 시스템은 사용자의 인터넷 경매 참여를 추천하는데 사용되며, 이 때 제안된 요소 선택 앨고리듬은 추천 규칙들이 쉽게 이해될 수 있도록 모델을 간략화 하는데 사용된다.

PSR: PSO-Based Signomial Regression Model

SeJoon Park,NagYoon Song,Wooyeon Yu,Dohyun Kim 한국지능시스템학회 2019 INTERNATIONAL JOURNAL of FUZZY LOGIC and INTELLIGE Vol.19 No.4

Regression analysis can be used for predictive and descriptive purposes in a variety of business applications. However, the successive existing regression methods such as support vector regression (SVR) have the drawback that it is not easy to derive an explicit function description that expresses the nonlinear relationship between an output variable and input variables. To resolve this issue, developed in this article is a nonlinear regression algorithm using particle swarm optimization (PSO) which is PSR. The output variables of PSR allow to obtain the explicit function description of the output variable using input variables. Three PSRs are proposed based on infeasible-particle update rules. Their experimental results show that the proposed approach performs similarly to and slightly better than the existing methods regardless of the data sets, implying that it can be utilized as a useful alternative when obtaining the explicit function description of the output variable using input variables and interpreting which of the original input variables are more important than others in the obtained regression model.