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IMEN 368 인간공학 II
10. Anthropometry and Work-Space Design
 Anthropometry – the study and measurement of human body dimensions
 HUMAN VARIABILITY AND STATISTICS
 Human Variability
 Age Variability
 Sex Variability
 Racial and Ethnic Group Variability
 Occupational Variability
 Generational or Secular Variability
 Transient Diurnal Variability
 Statistical Analysis
 Normal Distribution
 Percentiles
 ANTHROPOMETRIC DATA
 Measurement Devices and Methods
 height, breadth, depth, distance, circumference, curvature
 Civilian and Military Data
 civilian -- out-dated and limited
고려대학교 산업공학과
IMEN 368 인간공학 II
 Structural and Functional Data
 structural data (static data)
 taken with the body in standard and still position
 functional data (dynamic data)
 taken when the body adopts various working postures
 Use of Anthropometric Data in Design
1. determine the user population (the intended users)
2. determine the relevant body dimensions
3. determine the percentage of the population to be accommodated
 design for extremes
 design for adjustable range
 design for the average
4. determine the percentile value of the selected anthropometric dimension
 lower-limit dimension – physical size of the system, not the human user
 upper-limit dimension
5. make necessary design modifications to the data from the anthropometric tables
6. use mock-ups or simulators to test the design
고려대학교 산업공학과
IMEN 368 인간공학 II
 GENERAL PRINCIPLES FOR WORK-SPACE DESIGN
 Clearance Requirement of the Largest users
 lower-limit dimension, for the largest users (start with 95 %tile)
 Reach Requirement of the Smallest Users
 upper-limit dimensions, for the smallest users (start with 5 %tile)
 reach envelop (area) – the 3D space in front of a person without leaning forward or stretching
 Special Requirement of Maintenance People
 Adjustability Requirements
1.
2.
3.
4.
adjusting the workplace
adjusting the worker position relative to the workplace
adjusting the workpiece
adjusting the tool
 Visibility and Normal Line of Sight
 normal line of sight – the preferred direction of gaze when the eyes are at a resting condition
 about 10 to 15°below the horizontal plane
 Component Arrangement
 increase overall movement efficiency and reduce total movement distance
1. frequency of use principle
2. importance principle
고려대학교 산업공학과
IMEN 368 인간공학 II
3.
4.
5.
6.
7.
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sequence of use principle
consistency principle
control-display compatibility principle of colocation
clutter-avoidance principle
functional grouping principle
functional and sequence more critical than importance in positioning controls and displays
subjective judgment, link analysis, optimization approach
 DESIGN OF STANDING AND SEATED WORK AREAS
 Choice Between Standing and Seated Work Areas
 standing
 frequent movements in a large work area
 heavy or large objects or exert large forces with their hands
 use of floor mats and shoes with cushioned soles
 seated
 long-duration jobs
 allows for better controlled arm movements, provides a stronger sense of balance and
safety, improves blood circulation
 leg rooms or leg and knee clearance
 adjustable chairs and footrests
고려대학교 산업공학과
IMEN 368 인간공학 II
 seat-stand
 Work Surface Heights
 5-10 cm below elbow level for standing and at elbow level for seated – fig 10.9
 Work Surface Depth
 normal work area – a sweep of the forearm without extending the upper arm – fig. 10.10
 maximum – a sweep of the arm by extending the arm from the shoulder
 Work Surface Inclination
 slightly slanted surfaces (about 15°) for reading
 less trunk movement, less bending of the neck
 horizontal desk for writing
고려대학교 산업공학과
IMEN 368 인간공학 II
고려대학교 산업공학과
IMEN 368 인간공학 II
고려대학교 산업공학과
IMEN 368 인간공학 II
고려대학교 산업공학과
IMEN 368 인간공학 II
11. Biomechanics of Work
 awkward postures and heavy exertion forces – musculoskeletal problems
 low back pain and UECTDs
 THE MUSCULOSKELETAL SYSTEM
 support and protect body and body parts, maintain posture and produce body movement, generate
heat and maintain body temperature
 Bones and Connective Tissues
 protect internal organs – skull, rib cage
 support body movement and activities – long bones of the upper and lower-extremities
 Connective Tissues -- tendons, ligaments, cartilage, fascia
 joints -- synovial joints, fibrous joints (skull: fibrous tissues), cartilaginous joints (vertebral bones)
 no mobility joints, hinge joints, pivot joints, ball and socket joints
 Muscles
 400 muscles, 40 – 50% of BW
 supply energy and produce body motion
 generate heat and maintain body temperature
 muscle fibers, connective tissues and nerves
 a motor unit – “all-or-none”
 muscle contraction – concentric (isotonic), eccentric, isometric contraction
 no measuring device for tension in the muscle for muscle strength  torque or moment
 static/dynamic muscle strength (isokinetic equipment, psychophysics)
고려대학교 산업공학과
IMEN 368 인간공학 II
 BIOMECHANICAL MODELS
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musculoskeletal system as a system of mechanical links
bones and muscles act as a series of levers
Newton’s law
Body segment not in motion – static equilibrium
 The sum of all external forces on an object must be equal to zero
 The sum of all external moments on an object must be equal to zero
 Single-Segment Planar, Static Model
 LOW-BACK PROBLEMS
 Low-Back Biomechanics of Lifting
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the most vulnerable link because of most distant from the load
L5/S1
normal range of strength capability of the erector spinal muscle at low back is 2,200 – 5,500N
compression force on L5/S1
고려대학교 산업공학과
IMEN 368 인간공학 II
 Seated Work and Chair Design
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LBP is common – loss of lordotic curvature in the spine  increase in disc pressure
lordosis and kyphosis
seating – pelvis rotated backward  lumbar lordosis into kyphosis
backrest inclination angle – 110 to 120°
lumbar support – a pad in the lumbar region – thickness of 5cm
arm rest, tiltable seat surface
 UPPER-EXTREMILTY CUMULATIVE TRAUMA DISORDER
 Common Forms of CTD
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Tendon-Related CTD -- tendon pain, inflammation of tendon, tendonitits
Neuritis – tingling and numbing
Ischemia – tingling and numbing at the fingers
Bursitis – inflammation of a bursa
CTDs of the Fingers – vibration-induced white fingers (cold), trigger finger
CTDs of the hand and wrist -- CTS (carpal tunnel syndrome)
CTDs at the elbow -- Tennis elbow (lateral epicondylitis), golfer’s elbow (medial epicondylitis)
CTDs at the shoulder -- Rotator cuff irritation, swimmer’s shoulder, pitcher’s arm
 Causes and prevention of CTDs
 Repetitive motion, excessive force application, unnatural posture, prolonged static exertion,
fast movement, vibration, cold environment, pressure of tools or sharp edges of soft tissues
고려대학교 산업공학과
IMEN 368 인간공학 II
 Hand-tool Design
1.
2.
3.
4.
Do not bend the wrist
shape tool handles to assist grip
provide adequate grip span
provide finger and gloves clearances
고려대학교 산업공학과
IMEN 368 인간공학 II
고려대학교 산업공학과
IMEN 368 인간공학 II
고려대학교 산업공학과
IMEN 368 인간공학 II
고려대학교 산업공학과
IMEN 368 인간공학 II
고려대학교 산업공학과
IMEN 368 인간공학 II
고려대학교 산업공학과
IMEN 368 인간공학 II
고려대학교 산업공학과
IMEN 368 인간공학 II
고려대학교 산업공학과
IMEN 368 인간공학 II
고려대학교 산업공학과
IMEN 368 인간공학 II
12. Work Physiology
 MUSCLE STRUCTURE AND METABOLISM
 Muscle Structure
 primary function – generate force and produce movement
 smooth muscle – digestion of food and regulation of the internal environment – no conscious
control
 cardiac muscle – no conscious control
 skeletal muscle – the largest tissue in the body – 40% of body weight
 direct conscious control, physical work possible
 muscle fibers>myofibrils>sarcomeres (fig 12.1)
 sarcomeres – myosin and actin
 the sliding filament theory of muscle contraction
 Aerobic and Anaerobic Metabolism
 Phosphorylation – from ATP and CP to create high energy phosphate compounds through
aerobic and anaerobic metabolism (fig 12.2)
 Anaerobic
A. Phosphagen (ATP - CP) System
1. ATP  ADP + P + Energy
2. CP  C + P + Energy (rebound ADP and P to ATP)
고려대학교 산업공학과
IMEN 368 인간공학 II
B. Anaerobic Glycolysis System – oxygen debt, not efficient
1. Glucose (C6H12O6)n  Lactic acid (2C3H6O3) + Energy
2. Energy + 3ADP + 3P  3ATP
 Aerobic Reaction – steady state
1. C16H32O2 (carbohydrates and fatty acids) + 23O2  16CO2 + 16H2O + Energy
2. 130 ADP + 130P + Energy  130ATP
 THE CIRCULATORY AND RESPIRATORY SYSTEMS
 The Circulatory System
 The Blood
 8% of body weight
 red blood cells
 transport oxygen and remove carbon dioxide
 formed in bone marrow and carries the Hb
 white blood cells – fight germs and defend the body against infections
 platelets (혈소판) – stop bleeding
 Plasma – 90% water 10% nutrients and solutes
 The Structure of the Cardiovascular Systems
 the heart – four-chambered (atrium and ventricle, atrioventricular valves) – fig 12.3
 arteries and veins (one-way valves)
고려대학교 산업공학과
IMEN 368 인간공학 II
 the systemic circulation
 the left ventricle  aorta  arteries  arterioles  capillaries
 venules  veins  superior vena cava (inferior v.c.)  the right atrium
 the pulmonary circulation (oxygenation)
 the right ventricle  pulmonary arteries to the lung  arterioles  capillaries
 venules  veins  pulmonary veins  the left artium
 Blood Flow and Distribution
 the resistance to flow – blood vessel’s radius and length
 systolic pressure – the maximum arterial pressure
 diastolic pressure – the minimum
 arterioles are the major source to blood flow
 cardiac output (Q) – the amount of blood pumped out of the left ventricle per minute
 influenced by physiological, environmental, psychological, individual factors
 5 L/min for rest to 25 L/min for heavy work
 to increase the cardiac output -- increase HR or stroke volume (SV)
 Q (L/min) = HR (beats/min) * SV (L/beat)
고려대학교 산업공학과
IMEN 368 인간공학 II
 The Respiratory System
 The Structure of the Respiratory System
 the nose, pharynx (인두), larynx (후두), trachea (기관), bronchi (기관지)
 lungs – alveoli (200 mil to 600 mil)
 alveolar ventilation – the amount of gas exchange per min. in the alveoli
 the muscles of the chest, diaphragm
 Lung Capacity
 total lung capacity (fig. 12.4)
 minute ventilation (volume) – tidal volume x frequency
 increasing the tidal volume is more efficient than increasing the breathing frequency
 ENERGY COST OF WORK AND WORKLOAD ASSESSMENT
 Energy Cost of Work
 basal metabolism – the lowest level of energy expenditure to maintain life; a resting person
under dietary restrictions for several days and no food intake for 12 hours – 1600 to 1800
kcal/day or 1 kcal/kg/hour
 2400 kcal/day for basal metabolism and leisure and low-intensity everyday nonworking
activities
 Working metabolism (metabolic cost of work) – increase in metabolism from the resting to
the working level
 metabolic or energy expenditure rate during physical activity = working metabolism rate
(metabolic cost of work) + basal metabolism rate – fig. 12.5
고려대학교 산업공학과
IMEN 368 인간공학 II
 physical demand of work
 Light – smaller than 2.5 kcal/min – oxidative metabolism
 Moderate – 2.5 to 5.0 kcal/min – oxidative metabolism
 Heavy – 5.0 to 7.5 kcal/min – only physically fit workers through oxidative metabolism,
oxygen deficit incurred at the start of work cannot be repaid until the end of the work
 very heavy ( 7.5 to 10 kcal/min), extremely heavy (greater than 10 kcal/min) – even
physically fit workers cannot reach a steady state condition during the period of work –
oxygen deficit and lactic acid accumulation
 Measurement of Workload
 Physiological and subjective methods
 energy expenditure rate is linearly related to the oxygen consumption rate and to HR
 Oxygen Consumption
 Energy expenditure rate (kcal/min) = 4.8 kcal/liter * oxygen consumption rate (l/min)
 Oxygen consumption = aerobic metabolism during work + anaerobic metabolism during
recovery
 static work not well reflected in O2 measure
 Heart Rate
 indirect measure of energy expenditure, not as reliable as O2 consumption rate
 resting HR – 60 to 80 beats/min
 increase from the resting to the steady state is a measure of physical workload
 max HR = 206 – (0.62*age)
 max HR = 220 – age
고려대학교 산업공학과
IMEN 368 인간공학 II
 Blood Pressure and Minute Ventilation
 BP -- not used as often as O2 consumption and HR but more accurate for awkward static
posture
 minute ventilation (minute volume) – the amount of air breathed out per minute –
measured in conjunction with O2 consumption and used as an index of emotional stress
 Subjective Measurement of Workload
 Borg RPE (Ratings of Perceived Exertion) Scale of 6 to 20 (beats/min)
 PHYSICAL WORK CAPACITY AND WHOLE-BODY FATIGUE
 Short-Term and Long-Term Work Capacity
 Physical work capacity -- a person’s maximum rate of energy production during physical work
 the short-term maximum physical work capacity (MPWC) or aerobic capacity – VO2max – heart
cannot beat faster and the cardiovascular system cannot supply oxygen – 15kcal/min for healthy
male and 10 kcal/min for healthy female
 long-term maximum physical work capacity
 for continuous dynamic work, 5 kcal/min for male and 3.5 kcal/min for female
 Causes and Control of Whole-Body Fatigue
 experienced whole-body fatigue around 30 to 40% of maximum aerobic capacity
 certainly feel fatigued if the energy cost exceeds 50% of the aerobic capacity because the body
cannot reach the “steady state”
고려대학교 산업공학과
IMEN 368 인간공학 II
 Causes of fatigue  Accumulation of lactic acid in prolonged heavy work but not found with
prolonged moderate work; depletion of ATP and CP, symptom of disease or poor health
 engineering methods to reduce the risk of whole-body fatigue – redesign the job and provide job
aids
 administrative methods(work-rest scheduling) without heat stress
 rest period = (PWC – Ejob)/(Erest – E job)
 with heat stress
 Static Work and Local Muscle Fatigue
 Static muscle contractions impede or even occlude blood flow to the working muscles
 Rohmert curve – the relationship between endurance and %MVC
 EMG and psychophysical scales
 Engineering and Administrative methods
고려대학교 산업공학과
IMEN 368 인간공학 II
고려대학교 산업공학과
IMEN 368 인간공학 II
고려대학교 산업공학과
IMEN 368 인간공학 II
고려대학교 산업공학과
IMEN 368 인간공학 II
고려대학교 산업공학과
IMEN 368 인간공학 II
고려대학교 산업공학과
IMEN 368 인간공학 II
고려대학교 산업공학과
IMEN 368 인간공학 II
BORG’S RATED PERCEIVED SCALE
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
VERY, VERY, LIGHT
VERY LIGHT
FAIRLY LIGHT
SOMEWHAT HARD
HARD
VERY HARD
VERY, VERY, HARD
고려대학교 산업공학과
IMEN 368 인간공학 II
고려대학교 산업공학과
IMEN 368 인간공학 II
고려대학교 산업공학과