protected void experimentStart() {
		boolean isDuplicate = false;

		do {
			strSubjectID = JOptionPane.showInputDialog(this,
					"Please enter your participant ID:",
					"Dust & Magnet - Start Experiment",
					JOptionPane.QUESTION_MESSAGE);

			if (strSubjectID == null)
				return;

			isDuplicate = (new File(fileImport.getName() + "-" + strSubjectID
					+ ".log")).exists();

			if (isDuplicate == true) {
				int answer = JOptionPane
						.showConfirmDialog(
								this,
								"Participant ID (\""
										+ fileImport.getName()
										+ "-"
										+ strSubjectID
										+ "\") already exists. Are you still sure to use this participant ID?",
								"Dust & Magnet - Start Experiment",
								JOptionPane.YES_NO_OPTION,
								JOptionPane.WARNING_MESSAGE);
				if (answer == 0)
					isDuplicate = false;
				else
					return;
			}
		} while (isDuplicate == true);

		/**
		 * Logger setting
		 */
		FileHandler fh;

		try {
			fh = new FileHandler(fileImport.getName() + "-" + strSubjectID
					+ ".log");
			fh.setFormatter(new UserbehaviorFormatter());

			Logger.getLogger("").setLevel(Level.SEVERE);
			Logger.getLogger("").addHandler(fh);
		} catch (SecurityException e) {
			e.printStackTrace();
		} catch (IOException e) {
			e.printStackTrace();
		}

		/**
		 * Start the experiment
		 */

		log.severe("File/Start Experiment - Data set[" + fileImport.getName()
				+ "], Subject ID[" + strSubjectID + "]");

		/**
		 * Disable Start Experiment menu, and enable End Experiment menu
		 */

		mnuitemStartExperiment.setEnabled(false);
		mnuitemEndExperiment.setEnabled(true);
	}