부품외주를 고려한 조립형 Flowshop 일정계획문제 연구

전재호(Jae-Ho Juhn) 한국산업경영시스템학회 2006 한국산업경영시스템학회지 Vol.29 No.4

  This paper considers an assembly-type flowshop scheduling problem in which each job is assembled with two types of components. One type of the components is outsourced with positive lead time but the other type is fabricated in-house at the first stage. The two types of the components should be prepared at the first stage before starting the assembly operation for each job at the second stage. The objective is to schedule the jobs so that the makespan is minimized. Some solution properties and lower bounds are derived and incorporated into a branch and bound algorithm. Also, an efficient heuristic is developed. The performances of the proposed branch and bound algorithm and heuristic are evaluated through computational experiments.

우리나라 구제역 방역대책의 동태적 분석: 2010년 11월 구제역 감염을 중심으로

전재호 ( Jae Ho Juhn ) 한국시스템다이내믹스학회 2013 한국시스템다이내믹스 연구 Vol.14 No.4

The purpose of this paper is to find out some clues about effectiveness and implementing timing of the control measures against Foot-and-Mouth Disease (FMD) in Korea. To do that, the case of FMD, which broke out during November 2010 in Korea, is examined and constructed as a system dynamics simulation model. The implications of simulation result are as follows. First of all, it is most effective measure to prevent the movement of vehicle from infected farmhouse to other noninfected farmhouses, which are located far away, in the early stage of FMD diffusion. Secondly, earlier vaccination can be adopted as a reliable means to control the epidemic when FMD spreads widely. Finally, reducing the time to vaccinate the whole noninfected livestock is a little help to restrain the additional infections of FMD.

자체생산과 아웃소싱의 통합 생산일정계획 연구

이익선(Ik-Sun Lee),전재호(Jae-Ho Juhn),윤상흠(Sang-Hum Yoon) 한국산업경영학회 2010 經營硏究 Vol.25 No.4

본 연구의 목적은 제조업의 생산기능에서 아웃소싱수단이 존재하는 상황에서의 생산일정계획문제를 모델링하고 이에 대한 효율적인 해법을 제안하는 것이다. 즉, 개별 작업(또는 주문)의 처리가 자체생산설비를 통해 직접 수행되거나 외부설비(아웃소싱)에 위탁되어 조달되는 두 가지 선택이 모두 존재하는 경우에 수행해야 할 전체 작업에서 아웃소싱될 작업들에 대한 선택(job selection)과 전체 작업들에 대한 일정계획(job scheduling)을 동시에 결정하는 통합 의사결정 문제를 고려하고 있다. 자체생산설비와 외부설비는 각각 생산용량의 제약을 가지는 경우를 고려하였으며 어떤 작업이 자체설비를 통해 처리될 경우에는 해당 작업에 대한 일정계획비용(scheduling cost)이 발생하게 되고 그 작업을 아웃소싱하기로 결정할 경우에는 추가적인 아웃소싱 비용이 발생하게 된다. 본 연구에서는 총 아웃소싱비용에 대한 예산제약(budget constraint)이 존재하는 경우에 총 일정계획비용과 총 아웃소싱비용을 합한 전체 비용이 최소화 될 수 있는 아웃소싱 작업의 선택과 작업일정계획을 동시에 결정하게 된다. 해당 의사결정 문제는 NP-complete영역에 속한 문제로써, 최적해를 도출할 수 있는 동적계획법과 분지한계법, 그리고 큰 사이즈의 문제를 효율적으로 접근할 수 있는 발견적 해법을 동시에 제안한다. The objective of this paper is to present a new production scheduling model and an efficient method to solve the model in the case that there is an outsourcing option in the time-sensitive make-to-order environment. The orders(or, jobs) from customers can be either processed in a capacitated in-house facility or outsourced to subcontractors. Each job to be processed in-house induced the scheduling cost, otherwise the job is determined to be outsourced, then an additional outsourcing cost is imposed. This paper adopts the scheduling cost as the sum of completion times of all jobs. The objective of the scheduling model is to minimize the linear combination of scheduling and outsourcing costs under a budget constraint for the total available outsourcing cost in the capacitated in-house and outsourcing manufacturing environment. To solve the problem, we first should select jobs should be outsourced, and then we should determine both schedules for the in-house and outsourcing jobs. Thus, this problem considers an integrated decision problem for the job selection and sequencing. In the problem analysis, we first characterize some solution properties and then derive dynamic programming and branch-and-bound algorithms for the optimal solutions. An efficient heuristic is also developed because the problem belongs to the NP-complete context. The performances of the proposed optimal and heuristic algorithms are evaluated through various numerical experiments.

입학사정 투입시간과 입학사정관 전형의 효과

전재호 忠州大學校 2011 한국교통대학교 논문집 Vol.46 No.-

In this paper, it is examined how the amount of review time per applicant to a college admission system is connected with the academic performance of the selected students after they enter the college. About five years ago, college admission officers system has been introduced to Korea as a government policy. Thus, for most Korean college, there is not enough number of admission officers, while it takes substantial time to find out whether an applicant has potential ability or not. Thus, it is required to find out some policy alternatives to solve this discrepancy. In this paper, a simulation model is built using System Dynamics theory and simulated to find out the relation between the amount of review time and the academic performance of the selected students. Finally, some implications and policy alternatives derived from the simulation results.

2단계 조립일정계획의 총작업완료시간 최소화 알고리즘 연구

전재호 忠州大學校 2008 한국교통대학교 논문집 Vol.43 No.-

The n-job two-stage assembly scheduling problem is studied in this paper, with the criterion of minimizing the sum of job completion times. A mixed-integer programming model for the problem is developed and used to generate a lower bound by linear programming relaxation. Some solution properties are derived and incorporated into three heuristic algorithms. The computational results demonstrate that the performance of the proposed heuristic algorithms is superior over previous ones.

역전세 반환대출 규제완화 정책의 인과순환구조 분석

전재호 韓國交通大學校 2023 한국교통대학교 논문집 Vol.58 No.-

This study aims to assess the impacts of the 'Reverse Chonse' policy and draw out its implications, employing causal map analysis as the methodological approach. 'Reverse Chonse' pertains to a situation where the current 'Chonse' price is lower than the pre-existing 'Chonse' deposit. In response to this, the government is taking steps to relax regulations on loans that facilitate the return of 'Reverse Chonse' deposits. This is driven by the concern that tenants may encounter difficulties in retrieving their 'Chonse' deposits at the end of their lease period and the price of house may fall, owing to the phenomenon of 'Reverse Chonse.' The findings of this study can be summarized as follows. The primary objective of the policy, namely 'tenant protection,' seems feasible, with the exception of cases involving tenant scams or 'Can Chonse.' Here, 'Can Chonse' signifies that the current value of house falls below the existing 'Chonse' deposit. However, the secondary objective, which is to mitigate the decline in housing prices, poses challenges. This challenge arises due to certain tenants being ineligible for the policy and the unintended consequences it may generate. In addition, it is also found that the implementation of the policy could delay housing purchases by causing ‘expectations of a further decline in the housing market,’ which could lead to a decline in prices in the housing market. Hence, it is imperative to emphasize that the primary aim of this policy is the safeguarding of tenants, to mitigate potential misconceptions among consumers. Moreover, the policy exhibits an adverse side effect, manifesting as an escalation in household debt. Given that household debt levels in Korea have already reached a precarious state, a cautious and vigilant approach is warranted when implementing this policy.