Comfort Evaluation as the Example of Anthropotechnical Furniture Design

Human health is becoming an increasingly important issue in contemporary hectic lifestyle imposed at work and by struggle to save time and money. Sitting comfort and quality of chairs which we use for the most of our time have, thus, become essential for healthy lifestyle. Sitting discomforts arise from prolonged sitting on the inappropriate chairs, which failing to provide sufficient support to the body cause discomfort and tiring. The studies of the office chair constructions have identified differences in perception of comfort provided by different types of seats. Four seat constructions and the comfort they provide to the sitters were compared by means of subjective indicators. After a two-day sitting on each of the studied chairs the subjects scored their perception of comfort and discomfort, using the questionnaire with 17 statements. Constructional forms and materials which contributed more to the sense of comfort by minimizing fatigue and pains developed by sitting were determined

Pupils’ working postures in primary school classrooms

Background and Purpose: Primary schoolchildren spend most of their time in classrooms seated in chairs in some manner, but sitting behavior and working postures of pupils are rarely observed as an important criterion in school furniture design. Yet, correctly designed workspace for school children is, among others, one of the most important key factors in regular development of all abilities of youths. This research focused primarily on the pupils’ behavior at work, their movements and frequent activities during usage of tables and chairs in primary school classrooms, with the aim to identify main working postures and define them as notable criteria when designing school furniture for the future. Materials and Methods: The research was conducted in one elementary school in Zagreb, Croatia, with 18 pupils from the 2nd to 8th grades. The method employed was video recording. Results: Forty-three characteristic postures and semi-postures, classified in four main groups were recorded. The results showed that there are major differences in the subjects’ behavior and in the habits of using the task chair and tablewith respect to age, gender, daytime, studied subjects, tasks and the teachers’ behavior. Conclusions: Design of school furniture must take into account the age and anthropometrics of the child as well as analysis of characteristic postures of the pupils as one of crucial design criteria, to be observed both in 3D and 2D system. New school furniture design has to encourage sitting dynamics and fits psychological, ergonomic, physical, social and cognitive aspects of their users

Pametne uredske stolice sa senzorima za otkrivanje položaja i navika sjedenja – pregled literature

The health consequences of prolonged sitting in the office and other work chairs have recently been tried to be alleviated or prevented by the application of modern technologies. Smart technologies and sensors are installed in different parts of office chairs, which enables monitoring of seating patterns and prevents positions that potentially endanger the health of users. The aim of this paper is to provide an overview of previous research in the field of the application of smart technologies and sensors built into office and other types of chairs in order to prevent diseases. The articles published in the period 2010-2020 and indexed in WoS CC, Scopus, and IEEE Xplore databases, with the keywords “smart chair” and “sensor chair” were analysed. 15 articles were processed, with their research being based on the use of different types of sensors that determine the contact pressures between the user’s body and stool parts and recognise different body positions when sitting, which can prevent negative health consequences. Analysed papers prove that the use of smart technology and a better understanding of sitting, using various sensors and applications that read body pressure and determine the current body position, can act as preventive health care by detecting proper heart rate and beats per minute, the activity of individual muscle groups, proper breathing and estimates of blood oxygen levels. In the future research, it is necessary to compare different types of sensors, methods used and the results obtained in order to determine which of them are most suitable for the future development of seating furniture for work.Posljedice dugotrajnog sjedenja na uredskim i drugim radnim stolicama u posljednje se vrijeme pokušavaju ublažiti ili spriječiti primjenom suvremenih tehnologija. U različite dijelove uredskih stolica ugrađuju se pametne tehnologije i senzori, što omogućuje praćenje rasporeda sjedenja i izbjegavanje položaja koji potencijalno ugrožavaju zdravlje korisnika. Cilj ovog rada jest davanje pregleda dosadašnjih istraživanja u području primjene suvremenih pametnih tehnologija i senzora ugrađenih u uredske i ostale vrste stolica radi prevencije obolijevanja korisnika. Analizirani su članci objavljeni u razdoblju od 2010. do 2020. i indeksirani su u bazama podataka WoS CC, Scopus i IEEE Xplore, a izdvojeni su prema ključnim riječima pametna stolica i senzorska stolica. Obrađeno je 15 članaka u kojima su se istraživanja temeljila na primjeni različitih vrsta senzora koji određuju kontaktne tlakove između korisnikova tijela i dijelova stolice te raspoznaju različite položaje tijela pri sjedenju, čime se mogu prevenirati negativne posljedice za zdravlje. U analiziranim istraživanjima autori su dokazali da primjena pametne tehnologije i bolje razumijevanje sjedenja uporabom različitih senzora i aplikacija kojima se očitava pritisak tijela i određuje njegov trenutačni položaj može preventivno djelovati zahvaljujući praćenju rada srca i broja otkucaja u minuti, aktivnosti pojedinih mišićnih skupina, pravilnog disanja, procjene razine kisika u krvi i sl. U budućim istraživanjima potrebno je usporediti različite tipove senzora, primijenjene metode i dobivene rezultate kako bi se uočilo koji su od njih najprikladniji za budući razvoj radnog namještaja za sjedenje

Utjecaj vrste drva i presjeka na čvrstoću zavarenog moždanika

Rotation welding is a new method used in wood welding. Heat that develops due to the friction on contact surfaces softens and melts the wood structure (melt is produced). When the friction stops, the melt cools down and solidifies forming a firm joint. This research is based on the examination of the influence of various wood species and cross-sections on the strength of joints produced by rotational welding. Using rotation frequency and shifts in the orientation of the horizontal axis, a beech dowel is welded to a base made of common beach (Fagus sylvatica L.), pedunculate oak (Quercus robur L.) and Norway spruce (Picea abies L.) (hereinafter only beech, oak and spruce). Welding direction is both parallel to the orientation of the base fibres (PP) and perpendicular to the orientation of the base fibres (R, RT, T). Research results indicate that the dowel welded to the beech base retains the largest strength, whereas the dowel welded to the spruce base reveals the weakest results. Based on the research results, it can be concluded that beech dowels welded in the direction of beech and oak bases have the best strength of a joint. In spruce samples, reaction wood was used (compression wood in conifers) with somewhat different distribution of strength depending on the welding direction.Rotacijsko zavarivanje novija je metoda spajanja drva. Zbog trenja na kontaktnim površinama pojavljuje se toplina koja omekša i rastali strukturu drva (nastaje talina) te se formira spoj. Prestankom trenja drvo se hladi i talina otvrdnjava te nastaje čvrsti spoj. Istraživanje se temelji na ispitivanju utjecaja vrste drva i presjeka na čvrstoću rotacijski zavarenog spoja. Bukov moždanik je uz pomoć frekvencije vrtnje i pomaka u smjeru uzdužne osi zavaren u podlogu izrađenu od drva obične bukve (Fagus sylvatica L.), hrasta lužnjaka (Quercus robur L.) i obične smreke (Picea abies L.) (u daljnem tekstu: bukovina, hrastovina i smrekovina). Zavarivanje se obavljalo u smjeru vlakanaca podloge (PP) i okomito na njihov smjer (R, RT, T). Rezultati istraživanja pokazali su da moždanik zavaren u bukovu podlogu ima najveću čvrstoću, dok je najslabije rezultate pokazao moždanik zavaren u smrekovu podlogu. Iz rezultata istraživanja proizlazi kako bukov moždanik zavaren u smjeru vlakanaca bukove i hrastove podloge postiže najbolje rezultate glede čvrstoće spoja. Pri zavarivanju moždanika u smrekovinu rabljeno je i reakcijsko drvo (kompresijsko drvo četinjača) pa je raspored čvrstoće ovisno o smjeru zavarivanja bio nešto drugačiji

Istraživanje rastavljivih kutnih L-sastava namještaja za odlaganje

This research is based on the testing of the impact of the board (particleboard and medium density fiberboard (MDF)) and hardware type used to connect the sides and the bottom or top of the storage furniture on the joint strength. The hardwares of the following trade mark were used: the confirmat screw, Minifix, Maxifix, Stablofix, RV and Solo 32. Such hardwares make it possible to disassemble the furniture as well as to assemble it (when moving the furniture) without reducing joint strength when reassembling it due to wear and tear on the material (with the exception of the confirmant screw). Research results showed that assemblies with the Maxifix hardware installed in the MDF base exhibited the highest values of bending moment (the average bending moment of 85.88 Nm). On the other hand, assemblies with the Minifix hardware installed in the particleboard exhibited the lowest values of bending moment (over three times lower than the Maxifix) (the average bending moment of 24.50 Nm). Assemblies with the confirmat screw exhibited satisfactory results, although, aesthetic requirements seem to be the main problem here (the average bending moment of 40.38 Nm for the particleboard and of 64.24 Nm for the MDF).Istraživanje se temelji na ispitivanju utjecaja vrste drvne ploče (iverice i MDF ploče) i tipa okova koji služi za povezivanje stranice i poda ili stropa namještaja za odlaganje na čvrstoću kutnog spoja. Kao spojni okov rabljeni su oni trgovačkog naziva confirmat vijak, minifix, maxifix, stablofix, RV i solo 32. Navedeni okov omogućuje rastavljanje i sastavljanje namještaja (npr. prilikom selidbe namještaja) a da pri ponovnom sastavljanju ne bude narušena čvrstoća spoja zbog habanja materijala (izuzetak je confirmat vijak). Prema rezultatima istraživanja, najveće vrijednosti momenta savijanja zabilježene su u sastava s maxfix okovom ugrađenim u podlogu od MDF ploče (prosječni moment savijanja 85,88 Nm). Najmanje vrijednosti momenta savijanja (preko tri puta manje u usporedbi s maxifixom) izmjerene su za sastav s minifix okovom koji je ugrađen u ploču ivericu (prosječni je moment savijanja 25,40 Nm). Spojevi s confirmat vijkom pokazuju zadovoljavajuće rezultate momenta savijanja, ali su estetski zahtjevi glavni problem tog načina povezivanja elemenata (prosječni moment savijanja za troslojnu ploču ivericu iznosi 40,38 Nm, a prosječni je moment savijanja za MDF ploče 64,24 Nm)

The influence of users anthropometrical dimensions on the pressures while sitting in office chairs

Ovim su se istraživanjem nastojali otkriti trendovi i ponašanje materijala pod različitim opterećenjima i ovisno o drugim antropometrijskim značajkama ispitanika, utvrditi koliko i do koje razine indeks tjelesne mase (BMI) može poslužiti kao varijabla u sličnim mjerenjima i koliko je pouzdan. Cilj rada bio je ustanoviti ovisnost iznosa tlakova pri sjedenju o građi ljudskoga tijela i spolu. Mjerenja su provedena na tri modela stolica različitih konstrukcija sjedala (uokvirena mreža, poliuretanska hladno lijevana spužva i poliuretanska rezana spužva) na način da je deset ispitanika sjedilo na svakome modelu stolice prekrivenome mjernom prostirkom. Rezultati su analizirani s obzirom na antropometrijske osobine ispitanika i konstrukciju sjedala te uspoređeni s rezultatima prijašnjih subjektivnih istraživanja na istim konstrukcijama sjedala. Iz subjektivnih odgovora ispitanika uočeno je da su procjene vrsta materijala u ojastučenju na pitanje Osjećate li se udobno? jednake kao i u prethodnom istraživanju. Pri objektivnim mjerenjima u muškaraca se pojavljuju veći vršni tlakovi u apsolutnim iznosima, a s porastom indeksa tjelesne mase raste iznos najvišeg tlaka pri sjedenju. U žena su vršni tlakovi manji od onih u muškaraca, ali je uočeno da s porastom indeksa tjelesne mase ti tlakovi padaju.The aim of this research was to see the trends and material acting under influence of different loads and other anthropometric factors of subjects. Efforts were made to establish how much and to what extent body mass index (BMI) can serve as a variable in similar measurements and how reliable it is. The goal of the research is to establish the dependence of pressures on the human constitution and gender. The measurements were conducted on three different chair models (framed net, cold-casted PU foam and PU foam) and in a way that the ten subjects sat on a chair covered with the pressure mat. The results were analyzed in regard to the anthropometric characteristics of the subjects and the construction of the seat and they were compared with the results of the former subjective research conducted with the same seat constructions. The results of the subjective measurements show that the assessment according to the seat upholstery material as well as the answers to the question: Do you feel comfortable?, equal the results of the previous research. In the objective measurements, higher peak pressures occur with men in absolute amounts and the value of the highest pressure in sitting position grows with the increase of the body mass index. The peak pressures were lower with women than with men, but as the body mass index grew these pressures got lower

Study of the office chairs comfort regard to subjects characteristics

Dugotrajno sjedenje na neprikladnim stolicama koje nedovoljno pridržavaju tijelo i uzrokuju nelagodu i umor rezultira neudobnošću sjedenja. Istraživanjem konstrukcija uredskih stolica utvrđene su razlike u osjećaju udobnosti sjedenja na različitim vrstama sjedala. Istodobno je istraživan i utjecaj nekih ljudskih osobina i obilježja na osjećaj udobnosti. U radu su prikazani rezultati provjere statističke značajnosti razlika u subjektivnim procjenama udobnosti/neudobnosti s obzirom na spol, dob, visinu i masu ispitanika, zdravstvene tegobe i navike križanja nogu tijekom sjedenja, i to na četiri različite konstrukcije sjedala. Istraživanja su provedena na 36 ispitanika i sa 16 stolica. Ispitanici su nakon dvodnevnog sjedenja na stolici ocjenjivali osjećaje udobnosti/neudobnosti uz pomoć upitnika i odgovarajući na pitanja o postojanju određenih navika sjedenja i zdravstvenih tegoba. Razlike u procjenama među skupinama ispitanika provjerene su pomoću t-testa za neovisne uzorke. Istraživanje je pokazalo da ne postoje statistički značajne razlike testiranih varijabli i osobina ispitanika, ali da postoje neki trendovi.Prolonged use of anthropologically and ergonomically unsuited office task chair can cause discomfort and problems. The study about construction of office task chairs has shown differences of subjects feelings in the sitting comfort provided by various types of seating fillings. At the same time it was researched influence of some human characteristics on comfort feeling. Paper presents statistically significant differences in subjective evaluation of comfort/discomfort on four different seat constructions regarding to gender, age, height and mass of subjects, health problems and crossing legs habits during sitting. The study included 36 subjects and 16 chairs. After two days use of the chairs the subjects assessed their feeling of comfort and discomfort by ticking statements of the questionnaire about subsistence of specific sitting habits and health problems. Differences in evaluation among subject groups are checked with t-test for independent sample. Study showed no significantly differences in tested variables and subjects characteristics, but there are some trends

Office Work Chairs – Research of Deformations and Comfort Index

Konstrukcije sjedala i naslona uredske stolice kao predmeta čovjekove radne okoline važni su u njezinom konačnom rješenju jer su to elementi koji su izravno i usko povezani s ljudskim tijelom. Sjedeći je položaj najčešći radni položaj modernog čovjeka u industrijski razvijenom svijetu. Neovisno o vrsti posla, pravilan i fiziološki ispravan sjedeći položaj smanjuje zamor pri radu i opterećenje kralješnice, a odgovarajući povoljan položaj pri sjedenju uvelike pridonosi povećanju koncentracije i radnog učinka. Sjedeći radni položaj moguće je razmatrati usklađivanjem antropometrijskih veličina s oblikom sjedala i naslona ili, mehaničkim pristupom, utvrđivanjem odnosa između korisnika i kvalitete sjedala, pri čemu velik utjecaj ima indeks udobnosti. Indeks udobnosti stolice kao jedan od pokazatelja udobnosti sjedenja proizlazi iz mehaničkih svojstava promatrane stolice. U radu su prikazani rezultati tzv. mehaničke udobnosti koju stolica može pružiti korisniku. Rezultati određivanja udobnosti sjedenja na uredskim radnim stolicama prikazani su indeksima udobnosti stolica dobivenih iz elastičnih svojstava materijala sjedala i stolice prema tehničkoj specifikaciji HRS ENV 14443.Construction of the seat and back of the office chair, as an actual object of the human working environment, is important in its final design since these are the elements that are in a direct and close contact with human body. The sitting position is the most frequent working position of the modern man in the developed world. Independently of the type of work, a sound and physiologically correct sitting position diminishes fatigue during work and strain of the spine, and suitable posture during sitting significantly contributes to the increase of concentration and efficiency. Sitting as a working position can be examined through coordination of anthropometric sizes and form of the seat and back, or mechanically, by determining the relation between the user and the seat quality, where the comfort index or support factor has a great infl uence. The comfort index as one of the factors of sitting comfort is the result of mechanical characteristics of the observed chair. This paper shows the results of ‘’mechanical comfort’’ that the chair can offer to the user. The results of determining the seat comfort on office chairs are featured through comfort index obtained from elastic characteristics of materials in the seat, but also of the chair itself according to Technical Specifications HRS ENV 14443