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All Journal OPSI Jurnal Rekayasa Proses dan Industri Terapan Green Engineering: Journal of Engineering and Applied Science
Irwan Soejanto
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Agriculture, Biological Sciences & Forestry Chemical Engineering, Chemistry & Bioengineering Civil Engineering, Building, Construction & Architecture Computer Science & IT Electrical & Electronics Engineering Engineering Industrial & Manufacturing Engineering

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PENJADWALAN PROYEK DENGAN PENERAPAN SIMULASI MONTE CARLO PADA METODE PROGRAM EVALUATION REVIEW AND TECHNIQUE (PERT) Widya Nurul Shofa; Irwan Soejanto; Trismi Ristyowati
OPSI Vol 10, No 2 (2017): ISSN 1693-2102
Publisher : Jurusan Teknik Industri Fakultas Teknologi Industri UPN "Veteran" Yogyakarta

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (608.284 KB) | DOI: 10.31315/opsi.v10i2.2110

Abstract

PT At Taqwa Sejahtera has implemented of residential development that duration about 152 day. Due to delay in the supply of primary raw materials, the processing time getting longer or not accordance to planning schedule on October 27, 2017. The project delay have impact on the company which will given punishment.The aim of this study research to the evaluate the project implementation schedule and project scheduling for more optimal time, with the best probability, and minimize the influence of the causes of delays to the project completion time. Project scheduling processing is done by using Program Evaluation Review and Technique (PERT) and implementation with Monte Carlo simulation using Ms Excel software.Based on data processing, the calculation of the project point accelerated time to 147 days with cost Rp 417.315.909,25 and probability of 63%, whereas with the application of Monte Carlo simulus the average conviction rate is at 156 days with cost Rp 402,310,654.25 and probability of 94%.  
Penyeimbangan Lintasan Produksi Ribbed Smoke Sheet Untuk Meningkatkan Efisiensi Lintasan Menggunakan Metode Theory Constraint Novri Yohannes Harianja; Irwan Soejanto; Eko Nursubiyantoro
Jurnal Rekayasa Proses dan Industri Terapan Vol. 1 No. 3 (2023): Agustus: Jurnal Rekayasa Proses dan Industri Terapan ( REPIT )
Publisher : Politeknik Kampar

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.59061/repit.v1i3.321

Abstract

PT. Perkebunan Nusantara IX is a State-Owned Enterprise (BUMN) manufacturing rubber processing to produce Ribbed Smoke Sheets (RSS) located in Salatiga City, Central Java. Several things are not done by the company, namely the inefficient trajectory caused by the company's target being too high compared to the output produced. The production process has an imbalance in the trajectory, in which there is still an accumulation of materials/goods in process in several workstations so that actual production is not meet production targets, and the company is having difficulty meeting market demand. So it is necessary to balance the trajectory to answer these problems. Increasing the efficiency of the production balance can be obtained by balancing the trajectory using the theory constraint method aimed at reducing idle time and accumulation of goods so that the production process becomes more efficient. The method that can be used is CPM/PERT. The steps used are grouping work elements into workstations, calculating the value of workload, tracking efficiency, smoothing index, and balance delay, which are then compared based on the two methods. The results obtained are that the RSS production line has a high track efficiency value based on comparing the CPM/PERT method. Hence, the suggestion for the Ribbed Smoke Sheet (RSS) production line so that the line efficiency value is high following the CPM/PERT method is to make three workstations so that the value obtained is the track efficiency is 85% and increases by 21% from the initial track efficiency value, from 64% to 85%. The idle time value decreased from the initial 4.66 minutes to 1.51 minutes, the Balance Delay value also decreased from 37% to 16%, and the Smoothing Index value decreased from the initial 3.3 minutes to 1.08 minutes.
Developing an Integer Linear Programming Model for Hotel Shift Scheduling: Empirical Insights from a Central Java Hotel Irwan Soejanto; Trismi Ristyowati; Indun Titisariwati
Green Engineering: International Journal of Engineering and Applied Science Vol. 2 No. 3 (2025): July : Green Engineering: International Journal of Engineering and Applied Scie
Publisher : International Forum of Researchers and Lecturers

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.70062/greenengineering.v2i3.221

Abstract

Employee shift scheduling in the hospitality industry remains a critical yet complex task due to fluctuating operational demands, fairness requirements, and labour regulations. Many hotels still rely on manual scheduling methods, which are time-consuming and prone to biases, particularly in ensuring fair workload distribution across employees. Despite numerous studies on workforce scheduling, limited attention has been given to integer linear programming (ILP) models that address gender-based restrictions and operational fairness simultaneously in real-world hotel contexts, especially in developing regions such as Central Java. This study proposes an Integer Linear Programming (ILP) model to generate optimal shift schedules for hotel staff over a 31-day planning horizon. The model incorporates operational constraints, including one shift per day, gender-based restrictions (which prevent female staff from working night shifts), availability, minimum staffing levels, and fairness in workload distribution. Key parameters and binary decision variables were defined to ensure compliance with the hotel's specific requirements. Empirical data were collected from a hotel in Central Java involving 20 employees, and the model was implemented using Python with a Gurobi solver. The ILP model successfully generated optimal schedules in under 10 seconds, significantly outperforming the manual method, which required over 4 hours. While the manual schedule resulted in an imbalance where some employees worked over 27 days and others only 22, the ILP approach enforced a strict maximum of 26 working days for all staff. Furthermore, the fairness index (FI) improved from 19.2% in the manual method to 0% in the ILP-generated schedule, indicating complete equity in workload allocation. The proposed ILP model demonstrates its effectiveness in improving scheduling fairness, operational efficiency, and compliance with labour policies. This work not only addresses a critical research gap in hospitality scheduling practices in Indonesia but also offers a replicable framework for other labour-intensive service sectors. Future research may explore multi-objective extensions incorporating employee preferences, satisfaction, and dynamic demand fluctuations.
Co-Authors Indun Titisariwati Novri Yohannes Harianja Nursubiyantoro, Eko Trismi Ristyowati Widya Nurul Shofa