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IEEM 317 Product Design and Development Name: MODEL
Fall 2004, Exam I
Max Time 2 Hours, Max Score: 50 SID:


Question 1. Conceptual Design, Design evaluation [6+2+2]

(i) Given below is the sketch of a typical chair used in many classrooms in HKUST. Due to the position of the writing pad, different chairs must be used by right-handed or left-handed users.

Two alternate designs are proposed in which the same chair can be used by either right- or left-handed users. Compare the two new designs against the HKUST design using Pughs method.
For each rating you give, give a reason (1-2 lines max).

(ii) Based on your answers, which is the best design?

(iii) Write one point each for SWOT analysis of the better design among the two new ones.








Pad rotates open to allow user to sit
Both pads can be opened to sit
Arm rotates to allow user to sit
Pad can slide to left or right

Ease of sitting/getting up
(-)
(i) must rotate both pads to sit
(ii) cannot slide out and up from side, as in HKUST design
(-)
--same as Alternative 1--

Manufacturing cost
(-)
Extra pad, longer legs on left, extra assembly operations
(-)
Two moving joints (rotation, sliding), longer leg on left.

Convenience of use
(+)
More surface area
(+) (on average)
Can be used by left- and right-handed user

Ability to Stack-up chairs
(S)
Can be stacked
(S)
Can be stacked, with arm and pad rotated by less than 270



(ii) From the above, the two have same rating; further, both new designs can be very uncomfortable for fat users. Alternative 1 is perhaps a little better than Alternative 2, because (a) double moving joints on Alternative 2 may be less robust, (ii) the pad can move during use, causing potential irritation, (iii) Alternative 1 gives more surface area to keep your stuff.

SWOT:
S: Classroom can have fixed set of furniture even if % of left-handed users changes a lot.
W: More cost, not as comfortable to sit, get up, for fat users, etc.
O: high-class schools tend to have smaller class-sizes; this design may be attractive for rooms with very small number of users (since % of left-handed users can fluctuate a lot).
T: Other similar products in the market



Question 2. Product Family Design [4+4]
(a) Recall that Taguchi used his quality loss function, L = K(y C m)2, to determine the size ranges that should be offered. The optimal spacing between consecutive sizes of product is such that the cost per product for the manufacturer is equal to the average loss of quality to the society.
Assume that a manufacturer uses this method to determine three consecutive size steps for a product, and these sizes are given by: s1, s2, and s3.

State TRUE or FALSE, giving your reason:

The step sizes suggested by Taguchis method will be equal, namely, s2 C s1 = s3 C s2.


In general, this is FALSE.
Reasons:
(a) Taguchi al