Hayoung Jung

Measurement and Application of 3D Ear Images For Earphone Design

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.

Application of massive 3D head and facial scan datasets in ergonomic head-product design

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.

Development of HeadForms and an Anthropometric Sizing Analysis System for Head-Related Product Designs:

The present study developed a sizing analysis system based on the Civilian American and European Surface Anthropometry Resource (CAESAR) database of North Americans (n = 2,299) for head-related product designs. To find representative heads from a huge amount of 3D human scan database, a sizing analysis system is required for efficient analysis of sizing systems based on anthropometric measurements. The head of the CAESAR 3D scan were manually edited to improve a quality for better use to the product design. Twenty one anthropometric landmarks were marked on the edited 3D heads to measure 40 anthropometric dimensions related to the head product designs. All head and face dimensions were automatically measured by applying a measurement system coded using Matlab. Fifteen representative headforms were generated in terms of 5 ethnic groups (composite group, Caucasians, American Africans, Asians, and Hispanics) and 3 gender groups (composite gender, males, and females). Finally, the sizing analysis system was developed based on the measurement of the CAESAR for analysis of head and facial measurements and generation of sizing systems.

3D scan to product design: Methods, techniques, and cases

3D scanning technology has derived great opportunities for ergonomic product designs. This paper is aimed to introduce various research cases and methods based on 3D scanning have conducted by an ergonomics laboratory in South Korea. Sizing systems and representative 3D models developed on anthropometric measurements and 3D scan images with technical know-how were applied to the design of various products. Head, face, ear, upper limb, and waist parts, and full body in seated were anthropometrically analyzed for the design of headwear (e.g., helmet, goggle, and headphone), oxygen mask, earphone, arm-wear (e.g., watch, armband), hip protector, and vehicle seat, Customized software for the efficient analyses such as measurement of anthropometric dimensions, analysis of sizing systems, extraction of representative models, and virtual fit evaluation between products and the body were developed and applied in the product design process with massive 3D images. Representative models (e.g., torso and head) were printed in 3D for effective usage to the design and evaluation of related products. Advanced methods and techniques such as finite element modeling, morphing, and skin deformation have been applied to 3D scanned images for an advanced design of product shapes in further researches.

Development of an Ergonomic Method for Determination of Smartphone Hard Key Locations

The present study proposed a design method for determination of optimal hard key locations based on analysis of preferred grip posture and preferred hard key control area, and examined the effectiveness of the method by applying it to a smartphone with 5.0” screen. 45 participants were involved for analysis of preferred grip postures and another 44 participants were recruited for measurement of preferred hard key control area. Smartphone mock-ups which allow participants to adjust the locations of hard keys in their preference were developed having similar specification of real smartphone. L (left) 3 - R (right) 1 - K (back) 1 grip posture (82.6%) that the back side of the device is supported by the index finger and L (left) 4 - R (right) 1 grip posture (11.9%) that all five fingers contribute to grasp the device hardly were the most preferred for the smartphone with 5.0” screen. The optimal hard key locations were found 77 ~ 96 mm area from the bottom for the 20 mm right hard key and 88 ~ 97 mm area from the bottom for the 10 mm left hard key. A verification with real smartphones in various use contexts is needed to apply the results to the product design since the experiments were conducted in a laboratory setting with mock-ups.

Estimation of Instantaneous Hand Joint Centers of Rotation Using 3D Reconstructed Hand Skeleton Motion from CT Scans

The present study estimated instantaneous hand joint centers of rotation (CoR) using 3D reconstructed hand skeleton motions captured from CT scan. We proposed a novel method for estimation of instantaneous joint CoR using the same bone surfaces for different hand postures. Each bone in a template hand posture was registered to the corresponding bone of different hand postures. The registered hand postures (having the same bone surfaces as the template hand posture but different postures) with the template hand posture were then used for estimation of instantaneous joint CoR. The proposed method performed better than the existing methods in estimation of instantaneous joint CoR. Consistency of instantaneous joint CoRs determined in the same rotation angle range was improved by 31.7% to 51.0% in the proposed method. The present study focused on distal interphalangeal (DIP) and proximal interphalangeal (PIP) joints of the index finger of a participant. Joints of the whole hands of more participants will be studied for further generalization of the findings.

Anthropometric analysis of 3D ear scans of Koreans and Caucasians for ear product design

Abstract The present study measured 25 dimensions of the ear including the concha and ear canal for ergonomic design of ear products and compared with existing ear measurement studies. Scanning and casting methods were employed to produce 3D ear images for 230 Koreans and 96 Caucasians and measurements of the ear dimensions were obtained by identifying 21 landmarks on individual ear scan image. The Korean ear measurements were found significantly larger (mean difference  = 0.4–3.7 mm) and more varied (ratio of SDs =1.01–1.55) than those of Caucasians in most of ear dimensions. The average ear length and ear breadth of male were significantly longer ( = 1.3–7.0 mm) and wider ( = 0.8–3.0 mm) than those of female. Use of gender- and ethnicity-composite ear data is recommended in product design due to the much larger intra-population variations (7.5–22.2 mm) than the corresponding inter-population variations. Practitioner Summary: The 3D ear measurements of Koreans and Caucasians were collected and compared with those of different ethnic populations. The distinct ear features of the populations identified in this study are applicable to ergonomic design of ear products with better fit and comfort. Abbreviations: CCW: cavum concha width; CV: coefficient of variation; EB: ear breadth; EL: ear length; SD: standard deviation; SE: sampling error; 3D: 3 dimensional

An Ergonomic Evaluation of Convex Probe Designs Using Objective and Subjective Measures

Use of a convex probe suitable to the hand and operating motion of the probe can contribute to prevention of sonographers from musculoskeletal disorders at work. The present study presents an ergonomic evaluation process customized to convex array ultrasound probe design. Various convex probe designs were evaluated by a mix of nine sonographers and medical doctors in terms of EMG activities of the upper extremity muscles, motion ranges of the upper extremity joints, and subjective satisfaction measures. A randomized controlled testing was administered for the probe designs in a simulation workstation at a designated speed of tilting, pushing, and rotating of convex probe. The subjective satisfaction results were found effective to identify preferred design features in detail, while the EMG and motion analysis results to identify a preferred probe design overall in terms of muscular load at the hand and postural comfort of the forearm.

An Ergonomic Grip Design Process for Vaginal Ultra Sound Probe Based on Analyses of Benchmarking, Hand Data, and Grip Posture

The present study presents a systematic design process for the ergonomic design of a vaginal probe based on benchmarking, hand data, and grip posture analyses. Five existing vaginal grip designs were compared with each other using subjective measures to identify preferred design features for a new probe grip design. An in-depth analysis of the relationships between grip design variables and hand dimensions was conducted along with the consideration of preferred grip postures of vaginal probe and hand measurements. Two novel vaginal probe grip designs were proposed based on the analysis results of benchmarking, hand data, and grip posture. A validation experiment showed a significant improvement of the hand-data based vaginal grip design compared with the existing designs in terms of subjective satisfaction and wrist flexion.

Contact Pressure Analysis for Wearable Product Design

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.