Jangwoon Park

An anthropometric analysis of Korean male helicopter pilots for helicopter cockpit design

This study measured 21 anthropometric dimensions (ADs) of 94 Korean male helicopter pilots in their 20s to 40s and compared them with corresponding measurements of Korean male civilians and the US Army male personnel. The ADs and the sample size of the anthropometric survey were determined by a four-step process: (1) selection of ADs related to helicopter cockpit design, (2) evaluation of the importance of each AD, (3) calculation of required sample sizes for selected precision levels and (4) determination of an appropriate sample size by considering both the AD importance evaluation results and the sample size requirements. The anthropometric comparison reveals that the Korean helicopter pilots are larger (ratio of means = 1.01–1.08) and less dispersed (ratio of standard deviations = 0.71–0.93) than the Korean male civilians and that they are shorter in stature (0.99), have shorter upper limbs (0.89–0.96) and lower limbs (0.93–0.97), but are taller on sitting height, sitting eye height and acromial height (1.01–1.03), and less dispersed (0.68–0.97) than the US Army personnel. Practitioner summary: The anthropometric characteristics of Korean male helicopter pilots were compared with those of Korean male civilians and US Army male personnel. The sample size determination process and the anthropometric comparison results presented in this study are useful to design an anthropometric survey and a helicopter cockpit layout, respectively.

Analysis of the facial measurements of Korean Air Force pilots for oxygen mask design

This study measured the facial dimensions of Korean Air Force (KAF) pilots, to design a pilot oxygen mask, and compared them with those of Korean civilians and US Air Force (USAF) personnel. Twenty-two facial dimensions were measured for 278 KAF male pilots (KMP) and 58 KAF female pilots and cadets (KFP) using an anthropometer and a three-dimensional scanner. The KMP face measurements were found to be significantly larger (mean difference, = 0.7–26.5 mm) and less varied (ratio of SDs = 0.29–0.82) than those of Korean male civilians. The average face length, lip width and nasal root breadth of the KMP were significantly longer ( = 4.7 mm), narrower ( = − 2.4 mm), and wider ( = 5.2 mm), respectively, than those of USAF male personnel. Lastly, the KMP face measurements were significantly larger ( = 1.8–26.1 mm) than those of the KFP. Practitioner Summary: The face measurements of KAF pilots were collected and compared with those of Korean civilians and USAF personnel. The distinct facial features of the populations identified in this study are applicable to custom design of an oxygen mask for prevention of excessive pressure and oxygen leakage.

Analysis of the Facial Anthropometric Data of Korean Pilots for Oxygen Mask Design

The present study measured Korean pilots’ facial dimensions to design a pilot oxygen mask which would fit Korean pilots, and compared Korean pilots’ facial dimensions to Korean male civilians and US male pilots’ facial characteristics. The present study selected the 22 facial anthropometric dimensions related to oxygen mask design by referring to previous studies. The facial dimensions of 366 Korean male and female pilots (including 52 female cadets of the Korean Air Force Academy) were measured using Martin’s anthropometer and 3D scanner. Korean male pilots’ faces were significantly larger (mean difference = 1.3 ~ 27.0 mm) and less variable (ratio in SD = 0.29 ~ 0.85) than Korean male civilians’ faces (α = 0.05), which indicates that facial anthropometric data derived from Korean pilots should be used to design the oxygen mask for Korean pilots. In terms of criteria of the oxygen mask sizing system which is currently based upon the US Air Force anthropometric data (face length and lip width), Korean male pilots were significantly longer on face length (mean difference = 4.7 mm) and narrower on lip width (mean difference = -2.4 mm) than US male pilots (α = 0.05), which indicates that the oxygen mask sizing system as well as the oxygen mask shape should be changed for Korean pilots. Additionally, Korean male pilots have wider nasal roots (mean difference = 5.2 mm) than US male pilots, which indicates that the shape of nose of the current oxygen mask should be widened. Lastly, Korean female pilots’ facial dimensions were significantly smaller (mean difference = 0.6 ~ 26.1 mm) than Korean male pilots (α = 0.05), which indicates that Korean female pilots’ facial characteristics need to be considered in the design of oxygen masks which fit Korean pilots.

Statistical Models for Predicting Automobile Driving Postures for Men and Women Including Effects of Age

Background: Previously published statistical models of driving posture have been effective for vehicle design but have not taken into account the effects of age. Objective: The present study developed new statistical models for predicting driving posture. Methods: Driving postures of 90 U.S. drivers with a wide range of age and body size were measured in laboratory mockup in nine package conditions. Posture-prediction models for female and male drivers were separately developed by employing a stepwise regression technique using age, body dimensions, vehicle package conditions, and two-way interactions, among other variables. Results: Driving posture was significantly associated with age, and the effects of other variables depended on age. A set of posture-prediction models is presented for women and men. The results are compared with a previously developed model. Conclusion: The present study is the first study of driver posture to include a large cohort of older drivers and the first to report a significant effect of age. Application: The posture-prediction models can be used to position computational human models or crash-test dummies for vehicle design and assessment.

Development of an Evaluation Method for a Driver’s Cognitive Workload Using ECG Signal

Objective: The present study is to develop an effective evaluation method for a driver’s cognitive workload using electrocardiography (ECG) signal. Background: ECG measures such as heart rate (HR) and heart rate variability (HRV) have been used for cognitive workload evaluation. Since ECG changes by cognitive workload vary largely depending on personal characteristics, an optimal analysis protocol of ECG needs to be tailored to each individual accordingly; however, existing studies have not considered personal characteristics in ECG analysis for cognitive workload evaluation. Method: The proposed evaluation method uses the area under the receiver operating characteristic (ROC) curve (AUC). A preliminary analysis was conducted with ECG data collected in a driving simulator while an n-back task was conducted. AUC analysis was performed for four ECG metrics (mean IBI, SDNN, RMSSD, and RMSE), three window spans (20, 30, and 40 seconds), and three update rates (1, 2, and 3 seconds). Results: It was identified that the optimal ECG analysis parameters of metric, window span, and update rate maximizing the discriminability of cognitive workload evaluation varied between individual drivers. Conclusion: The finding of the present study supports the use of an individually customized ECG analysis protocol for better evaluation accuracy of a drivers’ cognitive workload. Application: The proposed ECG analysis method for cognitive workload evaluation can be applied to development of a safe driving support system.

Development of a textile sensibility evaluation system

As the demand in the market for a product with a high sensibility has dramatically increased, research has been conducted in designing products for better sensibility; however, most studies have employed a paper-and-pencil (P&P) questionnaire in administering a sensibility evaluation, causing a lack of efficiency and systematicity in sensibility research. The present study developed a computerized textile sensibility evaluation system which can be used to efficiently evaluate the visual, tactile, visual-tactile, and auditory sensibilities of textiles and examined its effectiveness in visual sensibility evaluation compared with the traditional P&P evaluation method. The computerized evaluation system has capabilities of managing information of textile properties, designing a sensibility evaluation experiment, administering a sensibility evaluation, and managing evaluation data for post hoc analysis. The test-retest protocol was administered with a within-subject design for 15 females in their 20 s and 30 s to examine the difference in visual sensibility evaluation between the P&P method and the computer-based method. A high correlation (r=.88∼.97) was found in sensibility evaluation between the two methods and the computer-based system showed a higher repeatability within a rater in repeated evaluation (a decrease of 25 % in intra-rater SD), which indicates the computer-based method is an effective alternative to the P&P method in visual sensibility evaluation. The findings of the present study support use of a computerized system for practitioners to efficiently identify preferred characteristics of textiles for the design of sensible clothing.

A statistical model including age to predict passenger postures in the rear seats of automobiles

Abstract Few statistical models of rear seat passenger posture have been published, and none has taken into account the effects of occupant age. This study developed new statistical models for predicting passenger postures in the rear seats of automobiles. Postures of 89 adults with a wide range of age and body size were measured in a laboratory mock-up in seven seat configurations. Posture-prediction models for female and male passengers were separately developed by stepwise regression using age, body dimensions, seat configurations and two-way interactions as potential predictors. Passenger posture was significantly associated with age and the effects of other two-way interaction variables depended on age. A set of posture-prediction models are presented for women and men, and the prediction results are compared with previously published models. This study is the first study of passenger posture to include a large cohort of older passengers and the first to report a significant effect of age for adults. The presented models can be used to position computational and physical human models for vehicle design and assessment. Practitioner Summary: The significant effects of age, body dimensions and seat configuration on rear seat passenger posture were identified. The models can be used to accurately position computational human models or crash test dummies for older passengers in known rear seat configurations.

Development of Quantitative Ergonomic Assessment Method for Helicopter Cockpit Design in a Digital Environment

For the development of a better product which fits to the target user population, physical workloads such as reach and visibility are evaluated using digital human simulation in the early stage of product development; however, ergonomic workload assessment mainly relies on visual observation of reach envelopes and view cones generated in a 3D graphic environment. The present study developed a quantitative assessment method of physical workload in a digital environment and applied to the evaluation of a Korean utility helicopter (KUH) cockpit design. The proposed assessment method quantified physical workloads for the target user population by applying a 3-step process and identified design features requiring improvement based on the quantified workload evaluation. The scores of physical workloads were quantified in terms of posture, reach, visibility, and clearance, and 5-point scales were defined for the evaluation measures by referring to existing studies. The postures of digital humanoids for a given task were estimated to have the minimal score of postural workload by finding all feasible postures that satisfy task constraints such as a contact between the tip of the index finger and a target point. The proposed assessment method was applied to evaluate the KUH cockpit design in the preliminary design stage and identified design features requiring improvement. The proposed assessment method can be utilized to ergonomic evaluation of product designs using digital human simulation.

Evaluation of Driving Posture Prediction in Digital Human Simulation Using RAMSIS

For proper ergonomic evaluation using a digital human model simulation (DHMS) system such as RAMSIS®, postures of a humanoid for designated tasks need to be predicted accurately. The present study (1) evaluated the accuracy of driving postures of humanoids predicted by RAMSIS, (2) proposed methods to improve its accuracy, and (3) examined the effectiveness of the proposed methods. Driving postures of 12 participants in a seating buck were measured by a motion capture system and compared with those predicted by RAMSIS. Significant discrepancies (8.7° to 74.9°) between predicted and measured postures were observed for different body parts and driving tasks. Constraint addition and user-defined posture methods were proposed and their performance was assessed in terms of prediction accuracy. Of the two proposed methods, the user-defined posture method was found preferred by improving the accuracy of posture prediction by 11.5% to 84.9%. Both the posture prediction accuracy assessment protocol and user-defined posture method introduced in the study would be of use for practitioners to improve the accuracy of predicted postures of humanoids in virtual environments.

An Analysis of Natural Motion for Product Design : Refrigerator Half Guard Installation Part Design

Ergonomic product design considering users` natural use motion is of importance to improve the usability and satisfaction of a product. A five-step process of product design was developed in the present study by measuring and analyzing users` natural product-use motion with a motion capture system. The developed process was applied to ergonomic design improvement of a half guard installation part of refrigerator; new guard designs (diagonal and arc shape) were developed with the process and evaluated in terms of validity during the development as two measures (task satisfaction and similarity of natural motion). According to the evaluation result, the satisfaction at putting in- and out-task of new guard designs ( points) was significantly higher than that of existing guard designs ( points); the difference between natural motion and product-use motion in new guard designs () was significantly less than that of existing guard designs (). The proposed process of natural motion analysis and product design is applicable to ergonomic product design and evaluation.