SYST 210

System Design

Kathryn Blackmond Laskey
Department of Systems Engineering and Operations Research
George Mason University
Homework Assignment 4: CORE Exercise
Due September 22, 2020, noon

Reading assignment: Chapter 3, 6.1-6.4

In this assignment, you will create a CORE model containing mission requirements and an external systems diagram for the UChekIt self-checkout system.  Your final submission must be neat and readable.  Every page must include your name, the assignment number, and the due date.   Please upload your assignment to Blackboard by the due date and time.

This assignment uses the CORE software.  CORE is installed in the VSE Lab in ENGR 1506. You can also install CORE on your home computer.  Instructions for installing CORE can be found in the MBSE Software folder on Blackboard. Install the CORE software on your computer as described in the installation instructions. Open CORE. Click "Model Assistant" in the Project pane and uncheck "Auto-create Root Functions." (This will prevent CORE from creating a performing function whenever it creates a component. We don't want to auto-create because we are going to create functions and components manually.) Also uncheck "Auto allocate on Decomposition", "Auto relate on allocation,"and "Auto-create root states." After you have become practiced in CORE, you may find  auto-create assistance useful, but when we are just getting started we will do these things manually.

We will work together on this assignment in class and you will complete it for homework.  If you need help with some of the steps, you can refer to the CORE tutorial on Blackboard, which walks you through the same steps in detail on a different system.
  1. Save the UChekIt Source Document on your local system, select the element extractor from the Tools menu, and load the source document into CORE. You will need to select "html" as the file type in the dialog box to open the file. Define a document called "UChekIt Source Document," and number it Doc.1. Select "Project Memo" as the document type.  In the "Description" field, copy the text of Section 1.0. Use Extractor > Create Element to make a CORE element for the document.
  2. Define a requirement MR.0 with name "Mission Requirements." For the description field, import the first sentence in Section 3.0 of the UChekIt Source Document. Define six mission requirements MR.1 through MR.6 corresponding to the six numbered mission requirements in the source document. Categorize them as originating requirements. Set the type of the first requirement to "composite;" the second and third to "perforamance;" the fourth requirement to "nil" (none of the listed types applies to this requirement); the fifth to "functional; and the sixth to "composite." Use the "refines" and "refined by" relation to make sure they are organized hierarchically in CORE with MR.1 through MR.5 refining MR.0. Link MR.0 to the source document via the "documented by" relation.
  3. Define a function F.0, "Provide Self-Checkout Services" in CORE to represent the top-level function for UChekIt.   Create functions for the external systems and the supersystem as described in the UChekIt Function Table.   Describe the  functions in the "description" field.
  4. Trace the top-level function to your top-level mission requirement using the "based on" and "basis of" relations. 
  5. Add items for each of the inputs, outputs and controls listed in the  UChekIt Function Table.  Connect these items to the functions using the "input," "output" and "trigger" relations in CORE. Use the "decomposed by" relation to decompose the item "messages to customer" into  "checkout opportunity" and "payment result message."
  6. Define components SYS.1 for the main system, ESYS.1 through ESYS.4 for the external systems, and CSYS.0 for the system context.  Enter descriptions for the components. Use the "built from" relation to connect the context to UChekIt and the external systems. Connect these components to their functions using the "allocated to" relation. These components should correspond to the mechanisms in the UChekIt Function Table. Trace SYS.1 to MR.0 using the "specified by" relation. 
  7. Run the "table maker" script by choosing "Run Script" from the Tools menu and choosing TableMaker from the drop-down menu.  Select "Requirements" as the segment.  Select attributes Number&Name, Description, Type, Origin, and Basis of. Select "Numeric" for the sort block. 
  8. Run the table maker script for components, selecting Number&Name, Description, built from, built in, and performs.  Do the same for functions, selecting Number&Name, Description, inputs, triggered by, outputs, allocated to, and based on.
  9. Select the source document and create a requirements diagram.  Use a note to put your name on the diagram. Save your diagram as a PNG file.  
  10. Select the Supersystem function and create an IDEF0 diagram. This is the UChekIt external system diagram).  Use a note to put your name on the diagram. Save your diagram as a PNG file.  If your functions are not in the same order as shown in the example, you can reorder them by selecting the function, right-clicking, and selecting Presentation / Change node order. (The CORE default background for all diagrams is blue. You may use the default or change if you prefer by right-clicking the diagram, selecting View > Local diagram options > Fill. Background color is a matter of preference and will not affect your grade.)
  11. Combine the tables you created in Parts 7 and 8, and the diagrams you created in Parts 9 and 10 into a report. Put each table or diagram on its own page, with an appropriate title at the top of the page. Make a cover page with the title: "UChekIt CORE Lab," your name, and the date. Make sure your name, the assignment number, and the date appear on every page. You can do this in MS Word using headers and footers.  Upload your report to Blackboard. You will be graded on the report you turn in. You do not have to submit your CORE model.

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