A 3D head and face scan data can be usefully applied in the ergonomic design of a wearable product such as an oxygen mask or a virtual reality (VR) headset to support the safety as well as comfort for a certain amount of a target population. This study is aimed to develop analysis and design methods of an ergonomic facial wearable products (e.g., pilot oxygen mask, VR headsets) based on numerous 3D face scan data (366 faces and 2,299 heads) through the template registration and the finite element (FE) analysis methods to predict the contact pressure between the face and a product. The application of the FE analysis on numerous 3D images to find an optimal form of a product is a novel approach in product design. The proposed methods on contact pressure analysis could be usefully applied for wearable products, which fit body parts.@en

3D body scanning has been used broadly including digital human modeling, simulation, ergonomic product design, and so forth. This research used template-registered faces of 336 Koreans in order to use them to design an oxygen mask that provides good fit to Korean faces. The finite element analysis method is applied onto the template-registered faces to predict the contact pressure of a mask design onto different faces. The average and variation of the estimated contact pressure values among all the Korean faces were analyzed for evaluation of the appropriateness of a mask design for Koreans. The proposed method can be usefully applied to find an optimal shape of wearable products for a specific target population.

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The present study developed a sizing analysis system for head-related product designs based on the Civilian American and European Surface Anthropometry Resource (CAESAR) database of North Americans. A total of 2299 heads in the CAESAR database were manually edited and 26 anthropometric landmarks were marked on the edited 3D heads to measure 30 anthropometric dimensions related to head-related product designs. The 3D anthropometric sizing analysis system (3D-ASAS) developed in the study provides analysis functions of a sizing system and representative face models by considering a target product, a target population, the number of size categories, and key anthropometric dimensions based on the CAESAR head measurements. Further research to reduce the efforts of manual editing and landmarking of 3D body scan data is discussed for efficient application of the 3D-ASAS to the design process of various wearable products.

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A revised pilot oxygen mask design was developed for better fit to the Korean Air Force pilots’ faces. The present study compared an existing pilot oxygen mask and a prototype of the revised mask design with 88 Korean Air Force pilots in terms of subjective discomfort, facial contact pressure, and slip distance on the face in high gravity. The average discomfort levels, facial contact pressures, and slip distance of the revised mask were reduced by 33%–56%, 11%–33%, and 24%, respectively, compared to those of the existing oxygen mask. The mask evaluation method employed in the study can be applied to ergonomic evaluation of full- or half-face mask designs.

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This study aimed to compare a three-dimensional (3D) semiautomatic measurement protocol (3D-SAMP) that measures hand dimensions using a plaster hand and a 3D scanner with the conventional direct measurement protocol (DMP). An experiment was conducted to measure 52 dimensions of one hand by 20 measurers with three repetitions. The locations of landmarks attached to the plaster hand were automatically identified and then measurements of the hand dimensions were automatically extracted in the 3D-SAMP. Significant measurement differences with a range of 2.1 to 4.4 mm between the 3D-SAMP and the DMP were observed in 13 out of the 52 dimensions, and the 3D-SAMP showed better reliability than the DMP in terms of intra- and intermeasurer variability. The 3D-SAMP was found significantly faster and easier in hand measurement than the DMP (11.1 ± 3.5 min for 3D-SAMP and 17.8 ± 4.5 min for DMP; 5.2 ± 0.8 for 3D-SAMP and 4.3 ± 0.8 for DMP using a 7-point scale with 1 for very dissatisfied and 7 for very satisfied for ease of measurement) when fabrication (about 1 hr 10 min) and scanning (3 min) of a plaster hand were not considered. The proposed 3D-SAMP is applicable only to plaster hands available in hand measurement.

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An artificial neural network (ANN) model was developed in the present study to classify the level of a driver's cognitive workload based on electrocardiography (ECG). ECG signals were measured on 15 male
participants while they performed a simulated driving task as a primary task with/without an N-back task as a secondary task. Three time-domain ECG measures (mean inter-beat interval (IBI), standard deviation of IBIs, and root mean squared difference of adjacent IBIs) and three frequencydomain ECG
measures (power in low frequency, power in high frequency, and ratio of power in low and high frequencies) were calculated. To compensate for individual differences in heart response during the driving tasks, a three-step data processing procedure was performed to ECG signals of each participant: (1) selection of two most sensitive ECG measures, (2) definition of three (low, medium, and high) cognitive workload levels, and (3) normalization of the selected ECG measures. An ANN model was constructed using a feed-forward network and scaled conjugate gradient as a back-propagation learning rule. The accuracy of the ANN classification model was found satisfactory for learning data (95%) and testing data (82%).@en

The present study developed and tested a new usability evaluation method which considers natural product-use motions. The proposed method measures both natural product-use motions (NMs) and actual product-use motions (AMs) for a product using an optical motion capture system and examines the usability of the product based on motion similarity (MS; %) between NMs and AMs. The proposed method was applied to a usability test of four vacuum cleaners (A, B, C, and D) with 15 participants and their MSs were compared with EMG measurements and subjective discomfort ratings. Cleaners A (44.6%) and C (44.2%) showed higher MSs than cleaners B (42.9%) and D (41.7%); the MSs mostly corresponded to the EMG measurements, which could indicate that AMs deviated from NMs may increase muscular efforts. However, the MSs were slightly different from the corresponding discomfort ratings. The proposed method demonstrated its usefulness in usability testing, but further research is needed with various products to generalize its effectiveness.

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Detail anthropometric dimensions and a 3D shape of the outer-ear are applicable to design ear-related products such as an earphone. However, 3D scanning of the ear part is quite difficult due to a complex shape of the ear, also detailed ear dimensions which are needed to be measured for earphone design were not identified in previous studies. This study collected 3D scan images of the whole outer-ear from 100 Korean participants (50 females and 50 males) aged 20 to 59, then measured their detailed ear dimensions for earphone design. The pinna part was directly 3D scanned; and complex shape of the concha and acoustic canal parts were cast by applying an ear casting tool, then the cast was scanned in 3D. 13 ear dimensions were measured by applying an ear measurement system coded using Matlab. Both 3D ear scans and ear measurements were applied to design some earphone parts (earphone-head, ear-band, ear-tip) in this study.@en

Abstract: 3D human body scan datasets have been collected and various techniques of post-processing, size and shape analysis, and applications in product design have been introduced. This paper is aimed to introduce techniques and cases of head-product design studies based on massive 3D head scan datasets. 3D scan datasets of the head, face and ear were collected and post-processed by editing, landmarking, alignment and measurement. For useful application of the 3D head scan datasets in head-product designs, we applied several analysis techniques such as development of a sizing system, selection of representative models, analysis of shape variation based on template-registered 3D scans and analysis of virtual fit. This paper can help understand an overview of techniques regarding massive 3D scan datasets and their applications to ergonomic product design.@en

An online suit-customizing system for the special accessibility needs of wheelchair users should be developed because the demand for business suits by wheelchair users involved in economic activities has increased. This study develops a user interface an online customizing system for men's suits specialized for wheelchair users. This study used a five-step approach: (1) search for online men's suits customizing system in web porter sites, (2) select three sites based on three terms, (3) heuristic testing with five web specialists, (4) development of a system user interface based on suggestions for improvement from the heuristic test, (5) usability testing of the user interface prototype by 10 disabled men in wheelchairs. The interface of Company S had high ratings on interactivity, accessibility, informativeness, and consistency in the heuristic test results; subsequently, a user interface was developed based on suggestions for improvement from the heuristic test. This online user interface for customizing men's suits provides better usability to wheelchair users than existing online interfaces aimed at the non-disabled and disabled; consequently, this study contributes to the commercialization of an online customizing system for men's suits specializing in serving wheelchair users.@en