Journal of Computer Science 9 (6): 733-739, 2013 ISSN: 1549-3636 © 2013 Science Publications doi:10.3844/jcssp.2013.733.739 Published Online 9 (6) 2013 (http://www.thescipub.com/jcs.toc) Corresponding Author: Octavia George, School of Computer Science, Bina Nusantara University-Jakarta, Indonesia 733 Science Publications JCS The Development of Expert Mood Identifier System using Fuzzy Logic on Blackberry Platform Octavia George, Maria Gorethi, Syerra Riswandi and Widodo Budiharto School of Computer Science, Bina Nusantara University, Jakarta, Indonesia Received 2013-01-15, Revised 2013-01-16; Accepted 2013-06-03 ABSTRACT In our daily life, deciding what caused the bad mood is not easy. This study will design an Expert Mood Identifier System for mobile application. We propose a model that uses 6 variables as the inputs, they are intensity of Sleep (SL), intensity of Eat (ET), hours of using Phone (PH), Spare Time (ST), intensity of Sensitive (SN), intensity of Confidence (CF). These inputs, using Sugeno fuzzy logic, are then fuzzificated to linguistic variables, so that they able to evaluated with the if-then rules. Result of the evaluation will show the highest possibility causes either in Love (LV) or density schedule. It will be defuzzificated to a crisp number showing the percentage of what causes it. The experiment results are presented and show the Mood Identifier system is running well on BlackBerry platform and can be used successfully to identify the causes of bad mood with a solution for each case. Keywords: Fuzzy Logic, Blackberry, Bad Mood, Expert Systems 1. INTRODUCTION Everyday our moods are so unexpected that it is hard to know where they come from, why they occur and what can be done about them. But these daily contrast in our feelings are actually easier to understand and manage than most people realize. If someone is an introvert-that is, someone with more of a quiet, shy nature-what he does or says tends to depend a lot upon how he feels. In other words, he is affected by his moods. If he is an extroverts, who focus more on the outside world, it is easier for him to ignore their moods. However, extroverts who ignore how they feel for too long can lose sight of their deeper human needs. As a result, they become stressed, no longer enjoy life and find that they’ve lost their purpose. It is very important to know what makes the mood change to worse and to solve it. In this study, we will use the fuzzy logic to calculate what the causes of bad moods, with knowledge from the expert of psychology. State of the art of this research is a new model of Expert Mood Identifier system using BlackBerry platform that very popular in Indonesia. 2. MATERIALS AND METHODS So far the method using technology to identify the causes of mood is using an interactive voice response system. It is a chance to solve this problem using questionnaires with different method. Defining a feeling is not only yes or no and it is not an exact number, but it can be represented with fuzzy set. For example, feeling good and bad is subjective, it is not only ‘good’ and ‘bad’, but can be ‘slightly good’, or ‘not too bad’. Thus we need a method that can use a imprecise and ambiguous values as the inputs, like fuzzy logic. 2.1. Theory of Moods Based on APA Dictionary of Psychology, a mood defines as any short-lived emotional state, usually of low intensity (e.g., a cheerful mood an irritable mood). Moods are a background feeling that persists over time that define how someone are. Usually moods are less intense and longer lasting than emotions, although the lower intensity is not true in a case of a serious