Dissertation Defenses

Doctoral Dissertation Announcement

---

Candidate: Anil Raghavendra Kumar

Degree of: Doctor of Philosophy

Department: Industrial and Manufacturing Engineering

Title: A Study to Investigate the Relationship Between a User’s Thermal Comfort and Seat Pan Materials

Committee:
Dr. Tycho Fredericks, Chair
Dr. Steven Butt
Dr. Leonard Lamberson
Dr. Christopher Cheatham
Dr. Teresa Bellingar


Date: Monday, June 18, 2007 10:00 a.m. – 12:00 a.m.
226 Parkview Campus

Abstract:
Workers performing sedentary tasks in job types such as administrative, technical, customer service and executive could be seated for four or more hours during their normal work shift. Due to the prolonged periods of sitting, a worker could experience dissatisfaction, discomfort and fatigue, which could lead to reduced performance. Symptoms of discomfort could over time lead to injuries and illnesses such as low back pain, cumulative trauma disorders, disc herniation, and pressure ulcers.
It is understood that posture and support affect discomfort and consequently have received wide spread attention from researchers. Another factor that could contribute to discomfort is the thermal influence of the seating surface. A common observation is that after a certain duration of sitting, the person starts to feel uncomfortable and tends to make small movements in the chair. These small movements are the human body’s response to either relieve pressure at the ischial tuberosities or a thermoregulatory response (i.e. the body is trying to dissipate heat that was built up at the skin or clothing interface) or both.
The primary focus of this research was to investigate the interactions of human-seat interface temperature on a user’s discomfort while performing a typing/mousing/reading task on different combinations of seat cushion materials for two sitting durations. A total of five seat pans with different combinations of cushion materials were used. Objective measures and subjective measures on 10 females were collected for a 5-minute sitting duration and a 3 hour sitting duration. The objective measure was temperature and subjective measures included ASHRAE Scale, Body Discomfort Map and Shackel Scale.
The results indicated that different combinations of seat cushion materials and sitting durations had an impact on the human-seat interface temperature. Furthermore, correlation between interface temperature and subjective ratings of comfort were found, which could aid designers in the selection of a combination of seat pan cushion materials.