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All Journal Jurnal Teknik Mesin Mechanova Jurnal Teknik Industri: Jurnal Keilmuan dan Aplikasi Teknik Industri Dimensi Utama Teknik Sipil
Didik Wahjudi
Program Studi Teknik Mesin, Fakultas Teknologi Industri, Universitas Kristen Petra Jl. Siwalankerto 121-131, Surabaya 60236,
Aerospace Engineering Automotive Engineering Civil Engineering, Building, Construction & Architecture Control & Systems Engineering Energy Engineering Industrial & Manufacturing Engineering Materials Science & Nanotechnology Mechanical Engineering

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Journal : Jurnal Teknik Industri: Jurnal Keilmuan dan Aplikasi Teknik Industri

 1 
OPTIMASI KUALITAS WARNA MINYAK GORENG DENGAN METODE RESPONSE SURFACE Didik Wahjudi; Lely Tjandranitia Dewi; Gan Shu San
Jurnal Teknik Industri: Jurnal Keilmuan dan Aplikasi Teknik Industri Vol. 1 No. 1 (1999): JUNE 1999
Publisher : Institute of Research and Community Outreach - Petra Christian University

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (59.695 KB) | DOI: 10.9744/jti.1.1.18-29

Abstract

Quality optimization of cooking oil color is done by performing experiment using samples of 98 gram cooking oil and 2 gram of whitening agent, i.e. bleaching earth and carbon active. There are three variables that affects the cooking oil color, i.e. temperature (X1) in the range of 90 to 110° C, stirring time of 10 to 20 minutes, and active carbon concentration (X3) of 5 to 15% (of the 2 gram of whitening agent). Response Surface Method consists of two-experiment designs, the first order and the second order experiment designs. The first order experiment design is the factor screening stage, while the second order design is the optimization stage. The first order experiment shew that only stirring time and the concentration of active carbon affects the color. The second order experiment resulted in that the appropriate optimization model is Y = 1,7833 + 0,0538 X2 0,1098 X3 + 0,0477 X2 X3 + e, and that there are three choices of optimal factor condition with regards of the whitening agent cost. Abstract in Bahasa Indonesia : Optimasi kualitas wama minyak goreng dilakukan dengan mengadakan eksperimen menggunakan sampel minyak goreng dengan berat 98 gram dan zat pemutih 2 gram, yang terdiri dari bleaching earth dan carbon active. Variabel-variabel yang mempengaruhi warna minyak goreng ada tiga, yaitu temperatur (XI) antara 90°C sampai 110°C, waktu pengadukan (X2) antara 10 menit sampai 20 menit, dan kadar CA (X3) antara 5% sampai 15% (dari 2 gram zat pemutih). Metode Response Surface terdiri dari dua rancangan eksperimen, yaitu rancangan eksperimen orde I dan rancangan eksperimen orde II. Dimana rancangan eksperimen orde I merupakan tahap penyaringan faktor (screening test), sedangkan rancangan eksperimen orde II merupakan tahap optimasi. Dari hasil eksperimen orde I, diperoleh basil bahwa variabel yang berpengaruh adalah waktu pengadukan dan CA. Hasil eksperimen orde II menyatakan bahwa model optimasi yang sesuai adalah Y = 1,7833 + 0,0538 X2 0,1098 X3 + 0,0477 X2 X3 + e, dan kondisi optimum faktor dengan pertimbangan biaya zat pemutih ada tiga pilihan. Kata kunci: desain eksperimen, rekayasa mutu
The Impact of After-sales Service Quality on Customer Satisfaction and Customer Loyalty of Middle-upper Class Landed Housings Didik Wahjudi; Timoticin Kwanda; Rianthi Sulis
Jurnal Teknik Industri Vol. 20 No. 1 (2018): June 2018
Publisher : Institute of Research and Community Outreach - Petra Christian University

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (319.118 KB) | DOI: 10.9744/jti.20.1.65-72

Abstract

Nowadays, good products are not sufficient. Market competition requires a good after-sales service. After-sales service quality has been identified as a source of revenue and competitive advantage. While other industry sectors have readily paid attention to after-sales service quality, little study has been done on the effectiveness of after-sales service quality in the field of real estate. This study aims to explore the relationship among after-sales service quality, customer satisfaction, and customer loyalty. Especially, we want to confirm the impact of after-sales service quality on customer satisfaction and customer loyalty of middle-upper class real estate in Surabaya. This research was conducted by survey on 170 respondents from four housing complexes in Surabaya, i.e. Pakuwon City, Citraland, Bukit Darmo Golf, and Graha Family. The data was examined by using structural equation modeling (SEM). Through data analysis we confirm the positive correlation between after-sales service quality and customer satisfaction, the positive correlation between customer satisfaction and customer loyalty, and the direct and indirect relationships between after-sales service quality and customer loyalty. The practical implication of this study provides assurance to real estate management on the effectiveness of after-sales service quality in maintaining old customers and encouraging new consumers.
Optimal Kiln Dry Allocation for Dry Timber Preparation to Minimize Cost Juliet Theresia; I Gede Agus Widyadana; Didik Wahjudi
Jurnal Teknik Industri Vol. 21 No. 1 (2019): June 2019
Publisher : Institute of Research and Community Outreach - Petra Christian University

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (383.527 KB) | DOI: 10.9744/jti.21.1.43-48

Abstract

Optimization models are increasingly developed for planning and scheduling in manufacturing of natural resources. However, the uncertainty of material from natural resources makes it more difficult to develop a model.  In this paper, we concern about the cost of dry timber preparation for finishing process in a wood-board manufacturer. Based on characteristics of the material and wood-board production process, we develop two models to minimize transportation and drying cost of wood supply. The models consider the capacity of facilities, distances among facilities, and timber specification-based drying periods. The model is solved using linear programming, result in drying allocation of kiln dry’s chambers that gives the minimum cost of the process. A sensitivity analysis is conducted to demonstrate the effect of variation of internal capacity and external capacity to the objective function value. The results show that the total cost is more sensitive to the variation of the external capacity of kiln dry than the variation of the internal capacity.
Co-Authors Amelia Amelia Amelia Amelia Andre Alexander Andreas Hartanto Andrew Cahyadi Arnold Phengkarsa Bernardus Trista Dmitri Sutrisno Daniel Ahendra Suwandi Didik Wahjudi Esa Saputra Fernando Gan Shu San Gan, Shu-San Glenn Eko Yulianto Hendra Kurniawan I Gede Agus Widyadana Januar Budiman Juliet Theresia Lely Tjandranitia Dewi Luke Sugiharto Susilo Nelson Sutanto Rianthi Sulis Richard Richard Ricky Kurniawan Njo Roche Alimin Roche Alimin Roynaldo Roynaldo Sugiarto Sugiarto Sutoto Yakobus Tanoto, Yopi Yusuf Timoticin Kwanda Timoticin Kwanda Tomy Suhartojo Victor Rizal Palapessy Yohan Pramono Yosua Lewi