Farklı yüklenmeler altında antropometrik verilere bağlı olarak fizyolojik parametrelerdeki değişimlerin incelenmesi

Abstract

ÖZET İleri Teknolojinin endüstrinin her alanına girdiği yüzyılımızda, tonlarca madde, hergün, ulaşım, taşıma, depolama, satış, bakım, vb. nedenlerle el ile taşınmakta ve kaldırılmaktadır. Oysa, insanın kas-iskelet sistemi, verimlilik açısından böylesi bir iş için tam uygun değildir. Bu nedenle, benzeri işlerde çalışanla rın fizyolojik kapasiteleri ve Antropometrik ölçüleri gözönüne alı narak el ile taşıma ve kaldırma işlemlerinin tasarlanması, sorunları bir ölçüde azaltacaktır. Günümüze kadar yapılan araştırmaların çok yönlü ve çok değişkenli olmaması, farklı yöntemlerin ve farklı değişkenlerin araştırmalarda kullanılmış olması. El ile kaldırma ve taşıma işlemlerinde, maksimum kaldırılabilecek yük miktarının belirlenememesine neden olmuştur. Bu nedenle, araştırmada metabolik, fiziksel ve elektriksel ölçütler kullanılarak, aşağıda özetlenen sonuçların elde edilmesi amaçlanmıştır: 1. Belli bir yaş grubuı go-26) » içindeki Türk Erkek nüfusunun Antropometrik Ölçülerinin saptanması, 2. Yük taşıma ve kaldırma işlemlerinde Antropometrik verilerin etkinliği, 3. Yük taşıma ve kaldırma işlemlerinin neden olduğu fizyolojik yüklenmenin belirlenmesi, 4. Eİ ile taşıma ve kaldırma işlemlerinde, maksimum iş yüklerinin belirlenmesinde etkin olan faktörlerin saptanması, 5. Fizyolojik yüklenmelere neden olan başlıca faktörlerin belirlenmesi, 6. Çeşitli değişkenlere bağımlı olarak, yük taşıma ve kaldırma modellerinin önerilmesi amaçlanmıştır. - XIV -

ANALYSIS OF VARIATIONS IN PHYSIOLOGICAL PARAMETERS UNDER DIFFERENT LOADINGS WITH RESPECT TO ANTHROPOMETR1CAL DATA SUMMARY In this era of high technology, tons of materials are handled manually each day during transportation of raw and finished goods» production, storage, sale and maintenance. Since the human skeletal system is not an ideal device for manual work, and because, the required manual activity often exceeds workers' physical limitations, workers are injured and force to leave the workplace and seek treatment. In the past two decades, extensive research has been conducted to develop quidelines and procedures for reduction and prevention of Manual Materials Handling related injuries. The design criteria for establishing lifting capacity norms should take into account both potential risk of injury as well as work efficiency (Garg and Ayoub,1980). Unfortunetely, the load recommendations based on the 10. th percentile of the population, though considered safe for 90 %of the population, are not desirable since the work efficiency of some workers is significantly impaired. On the other hand, the use of load limits acceptable to a small part of the population v90.th percentile/ is likely to result in injuries to weaker workers. The optimal solution, therefore, should provide for a significant reduction in the risk of injury as well as reasonable levels of work efficiency. The problems associated with Manual Materials Handling may be approached by two somewhat opposing philosophies. The first would entail setting lifting standarts so low that, literally everyone would be able to perform the lifting task repetitively for extended time periods without incurring either fatique or bodily injury. This, however could adversely affect the efficiency of lifting and carrying tasks. The second approach if followed to its extreme, would entail relaxing the lifting standarts in an attempt to optimize the working efficiency at the expense of worker safety (Ayoub,1979). Either of these approaches, if carried to these extremes would be unsatisfactory. Grand jean (1980) pointed out that, when considering lifting and carrying of loads, both working efficiency and the prevention of damage to the spine should be considered. Assuring that job demands do not exceed workers' capabilities is the responsibility and goal of those in the field of Ergonomics, the object of determining work capacity in the industrial sphere is to fit the job to the worker so that he can work without fatique or harm to his health. If a person's capabilities are known, they may be used as a criterian for job design. In Manual Materials Handling tasks, a person must be capable of performing without excessive strain or fatique. Especially, in repetitive lifting and load carrying, large - xv _muscle groups perforin submaximal, dynamic contractions. During this type of work, a person's endurance is primarily limited by the capacity of the oxygen transporting and utilization systems. Thus, the pulmonary system( lungs), the circulatory systems heart and blood pressure^, and the metabolic system (energy consumption) establish the central limitations of a person's ability to perform streneous work. A person's capability for labor is limited also by muscular strenght and Anthropometric dimensions. These are local limitations for the force or work that a person can exert. While handling and carrying loads, the force exerted by the hands must be transmitted through the whole body (via wrists, elbows, shoulder, trunk, hips, knees, ankles and feet) to the floor. In this chain of force vectors, the weakest link determines the capability of the whole body to the job. If muscles are weak or if they have to work at mechanical disadvantages, the handling force is reduced. A particularly weak link in this chain of forces is the spinal column, particularly at the low back. Muscular strain or painful displacements of the vertebrae and/or of the intervertebral discs often limit a person's ability for Manual Materials Handling. Many models have been developed to describe the central and local limitations just described (Ayoub etc.,198o). Simplified for convenience, they may be grouped as follows: 1. PHYSIOLOGICAL models provide information on energy consumption, and the loading of the circulatory system. 2. BIOMECHANICAL models provide information on strain capabilities of the body, particularly of the spinal column and its discs, and on the effect of body segment positions on available muscle strenght. 3. PSYCHOPHYSICAL models combine objective performance measures and subjective assessments of the perceived strain. They provide synergistic information on Manual Materials Handling capabilities and limitations. However, limits computed by use of these criteria differ significantly with respect to the weights to be lifted safely. Most of the proposed limits are based on a single criterion and consider only a single stress response of the worker to a lifting task lMital,1983)` in Chapter 3, Table 3-6, most of the research results were summarized. Although a great deal of useful information has been provided by researchers concerning maximum permissible weight of lift, these efforts did not however, yield a predictive lifting model. This is because, inadequate measures of strenght. Anthropometric and metabolic measures were recorded and correlated with lifting capacity. - xvi -The data derived from the study was aimed to provide an estimate of the lifting capacity of the industrial work force which can be used as a guide by using both physiological and Anthropometric variables. Except strenght variables, the number of variables used in the study were higher compared with the similar studies. The research conducted uses both the physiological and psychophysical approaches in order to define acceptable load limits. Since the human capabilities, characteristics (static and dynamic strenght, sex, experience, etc. ) and responses to a task differ widely, each case of simulated Manual Materials Handling task was considered individually and independently. The experimental procedure of the research consisted of two parts. In the first part, a detailed Anthropometric survey was conducted among soldiers, aged between 18-22 years in Erzincan and Ankara, bl Anthropometric measurements, which aimed to be used in various designs were obtained using a standart Anthropometer from 5109 soldiers (Chapter 4.l). Regression models were developed to predict the value of different Anthropometric variables in Chapter b.2.1. The predictive capabilities of most of the models were higher than 85%. In the second part of the study, 25 soldiers were taken to the simulated lifting and carrying tests. In the lifting and carrying tests, several physiological measures were obtained in order to determine the maximum task intensity that can be continuosly performed without accumulating an excessive amount of physical strain in repetitive lifting. Besides Antropometric measurements, the following measurements were obtained during lifting and carrying tests: 1. Heart Rate (beats/min), 2. Amount of ventilation (lt/min), 3. Systolic blood pressure (mmHg), 4. Diastolic blood pressure (mmHg), 5. Hand grib strenght (lb), 6. Skinfold thickness (mm), 7. Maximal Oxygen uptake (lt/min), 8. Recovery time (sec), 9. Energy expenditure (kcal/min). 10. Fat(%) The measurements were taken in such a manner or frequency such that the subjects recovered from fatique before continuing with the next measurement. The culmination of rest allowances between measurements was determined when the subject's heart rate returned to his resting heart rate measured prior to conducting the tests. For repetitive lifting (where the weight of the load is presumed within the physical strenght of the worker), the problem becomes one of physical fatique. So the amount of increase in heart rate is allowed to be compared with the resting heart rate. - XVI 1An adjustable platform was designed to perform lifting and carrying tasks. The loads were lifted and carried in different ways. Some subjects lifted the load vertically from the floor to their either waist height or shoulder height, some lifted the load from their waist height, carried it horizantally 2.0m. and locate it either to their waist height or shoulder height. Thus, there exists 6 different lifting and carrying heights in the study. The selection of these heights was made on the basis of the muscles or muscle groups involved in the performance of the lift. These lifting ranges required, using both leg and arm muscles. The subjects decided on the amount of weight according to the frequency and lifting height. The amount of weight allowed to be lifted did not exceed 50 % of the subject's weight in order to prevent the probable injuries. Different weight modules were prepared ranging from 2.5 kg to 10 kg in different shapes, so that subjects could adjust the amount of weight that they could lift repetitively for 5 minutes during the test. The subjects were continuosly instructed to adjust workload to the maximum amount that they could perform without strain or discomfort or without becoming tired, weakened, overheated, or out of breath. The effect of frequency in different lifting heights was found to be insignificant at 5 % level using T-Test analyses. Using Analysis of Variance (.ANOVA) tests, the effects of frequency and lifting height were found significant at 5 % level, while their interactions was not. Similarly, the effect of frequency on the amount of ventilation, heart rate, blood pressure and recovery time was about 24 %, 23 %, 18 % and 10 %. The effect of lifting height on most of the physiological parameters was about 7 %- The maximum weight lifted by each subject for each level of lift showed correlations with several physiologic and Anthropometric variables. In Chapter 5.3.2., the results of correlation analyses was given in Table 5-27. This study showed that, maximum workload acceptable to the workers increased with an increase in lifting frequency vup to 12 lifts/min employed in this study,. For example, the workers did not decrease the weight of the load in proportion to an increase in lifting frequency. Therefore, if the recommendations for the maximum work load was based on a high value of lifting frequency they may cause excessive physical fatique and musculoskeletal injuries. On the other hand, if a low value of lifting frequency was used to develop these recommendations, they would result in conservative estimates of allowable workloads when applied to higher frequencies, hence, leading to a decrease in productivity. One practical issue was that, as a man-machine system designer, we would like to know the frequency of lifting that _ xviii -maximizes mechanical efficiency of the human body and minimizes the cardiac output per unit time. In Chapter 5.1., between tables 5.14 and 5.22, under different lifting and carrying heights and frequency according to the workload, the energy expenditure, mechanical efficiency and cardiac output values of the groups were given. As it was seen from these tables, minimum cardiac output and maximum mechanical efficiency values were obtained if frequency was more than 8 lifts/nun. But considering the probable musculoskeletal injuries and physical fatique for repetitive lifting activities, the maximum allowable loads to be lifted under different frequencies and heights were determined in Table 5-26. The procedure used was the following : When lifting frequency increases, the amount of load to be lifted which was found as a function of frequency, height and percentile value of the loads should be decreased by multiplying it with the coefficient (c), that Aghazadeh (1975) proposed. Maximum load lifting capacity = W(f,h,%)*c (kg) where; f=frequency, h=height, %=percentile value calculated from Table 5-25, c=coefficient that varies according to the frequency. The lifting capacity data are useful as a guideline for designing lifting jobs or redesigning existing jobs. For example, at six lifts/min, from floor to waist height, 75% of the males can lift 10.9 kg maximum (table 5-26). Therefore, weights below this value should be the design target for males. On the other hand only 10% of the population can lift 19 kg maximum. Thus weights above this value should not be lifted by a single male worker. The maximum weight lifted by each subject for different level of lift, showed correlations with several individual variables. So the maximum weight lifted was considered as a dependent variable and several Anthropometrical and physiological variables were independent variables. These independent variables were considered for the development of lifting capacity predictive models. These models were formulated using a Stepwise Regression Program. Predictive capability of the model was about 83 %, which was higher than most of the predictive capacity models developed by different researchers (Chapter 5.3.6.1»). Finally, relations especially between physiological variables were modelled using polynomial, exponential and power equations (Chapter 5.3.6.2.). - xa x-BOLUM 1. GİRİŞ Uygarlık tarihi ile Mühendislik bilimlerinin gelişimi arasında bir paralellik kurulabilir. Çağdaş bilimin yaşantımızdaki uygulamaları ancak çeşitli mühendislik alanlarındaki çabalar sonucu mümkün olmaktadır. Böylelikle, nükleer silahların gölgesinde de olsa, tüm dünyada yaşam standardı yükselmekte ve makinalar sayesinde yapılan her türlü üretim ve hizmet, nitelik ve nicelik yönünden belli ilerlemeler kaydetmektedir (Özok, 1982). Bilindiği gibi, Makina, İnşaat, Kimya, Elektrik, vb` mühendislik dalları ile Endüstri Mühendisliği arasındaki en önemli fark, Endüstri Mühendisliğinin `İnsanı` incelemesidir. çünkü, insan, makina ve malzemeden oluşan üretim öğeleri içinde en önemli olanı insandır. Ayrıca, üretilen herşey de, esasen insan içindir. İnsanın üretim ya da hizmet amacıyla birlikte çalıştığı basit veya karmaşık her türlü tezyah, araç-gereç, vb.'ni Makina olarak isimlendirirsek. Endüstri Mühendisliğinin en önemli uğraşı alanlarından birinin de İnsan-Makina Sistemleri olduğunu görürüz (Şekil 1-1). İnsan-Makina sistemleri, basit, mekanik veya otomatik sistemler olarak isimlendirilir (Özok, 198?). Birey ve toplum, hem yaşamını sürdürmek ve hem de ilerleyebil mek için bir takım etkinliklerde (faaliyetlerde) bulunmak zorunda dır. Bu tür etkinlikleri `İş` olarak tanımlarsak, onu bilimsel olarak incelemenin ne derece önemli olduğu kendiliğinden ortaya çıkar. Yaşantımızın hemen her safhasında iş yaptığımıza göre, bu konuda çağdaş bilimin ortaya koyduğu verilerden yararlanmak, özellikle ülkemiz gibi hem kaynakları kıt ve hem de onları iyi değerlendiremeyen ülkeler için büyük önem taşımaktadır. Son yıllarda yapılan araştırmalar. Ergonomi biliminin Üretim sistemlerinin verimliliğine yönelik çalışmalara büyük katkısı olduğunu saptamıştır. İnsanın çalışması esnasındaki fizyolojik.