There is an increasing demand for “natural” products by consumers, businesses, scientists and product developers. Trends suggest that the term natural may be colloquially understood to be a plant-based material or ingredient. This study investigates whether this trend could apply to polymers by declaring the derivation of the polymer as a plant or as petroleum. Because polymer materials do provide environmentally positive attributes for products in relation to other materials, such as lightweighting, durability, and lower fabrication energy requirements, it may be helpful to understand the influence of a polymer’s derivation on the perception of a polymer product’s sustainability. The goal of this study is to assess peoples’ relative perceptions of the sustainabilities of polymer drinking cups when the base materials from which the polymers were derived are exposed. A set of six injection-molded drinking cups was given to research subjects to analyze. Each cup is made of a different polymer. The polymers have derivations including petroleum, corn, sugar and trees. Participants evaluated the cups on six qualitative design strategies for sustainability, including natural-ness. This paper compares the perceived sustainable attributes of the cups, and which attributes were most strongly influenced by revealing the derivation of the polymers.

It is said that the relationship between “novelty” and hedonic response is expressed as an inverse U-shape. The latest studies about perception emphasize “novelty” as a factor of emotion and quantify “novelty” by assessing the difference in amount of information using Kullback-Leibler (KL) divergence. In this study, we proposed a novelty index of closed surfaces using KL divergence focusing on their curvatures. To calculate novelty index, we firstly calculated Gaussian curvature of each vertex in the shape. Then, we defined occurrence probability distribution which represents probability that a vertex has a certain curvature. The KL divergence expresses the difference between the occurrence probability distributions of the standard shape and the target shape. To confirm the effectiveness of the proposed index, we conducted the cognitive experiment using the shape samples of an automobile generated by particle swarm optimization method. The coefficient of determination between the proposed index and sensory evaluation values of “difference” were very high which support the applicability of the index. Furthermore, the consideration of location information increased the correlation with sensory evaluation. This suggests the possibility to evaluate an industrial design requirement quantitatively and contributes to develop the automatic shape generation in product design.

In recent years, deep learning has attracted much attention and various techniques have been proposed. GAN (Generative adversarial networks) is one such method. When images are used as the training set, this technique learns to generate new images that are indistinguishable from the images of the training set. Using this method, new face images of non-existent people can be generated from the face images of real people, or input images can be converted into the images with the style of a particular painter such as Monet.

In this study, using this capability of GAN, a method of generating a new product design from the images of customer's favorite products is proposed. The product images that customers evaluated as preferable in the kansei evaluation are used as the training set of GAN. Since the GAN generates images that are indistinguishable from the images in the training set, the new images generated are more likely to be preferred by customers.

In the case study, the proposed method was applied to the chair design. Subjects evaluated their preferences for images of various types of chairs collected from the Internet, and new chair images were generated based on the chare images that subjects evaluated as preferable. The generated chair images were first evaluated in terms of image quality, i.e., whether they looked like chairs or not, and how innovative they were compared to existing chairs, and then subjects evaluated their preferences.