土木工程英文文献

KSCEJournalofCivilEngineering(2011)15(1):23-31DOI10.1007/s12205-011-0983-5−23−*,Hyun-sooLee**,MoonseoPark***,andJung-HoYu****ReceivedSeptember8,2009/AcceptedApril8,2010···································································································································································································································AbstractAlthoughconstructionproductivityhasreceivedagreatdealofattentionfromconstructionpractitionersandresearchers,fewresearcheffortshavespecificallyevaluatedproductivityinthecontextoftheproductivitymanagementcycle.Consequently,thereisstillalackofusefulindicatorsfordeterminingwhichitemsshouldbeprioritizedandimproveduponinordertoyieldthehighestbenefitsfromproductivitymanagement.Inanefforttoaddressthisissue,thisstudyproposestheProductivityAchievementRatio(PAR),whichisaproductivityevaluationindicatorthatwillassistintheselectionofthemostappropriatemanagementitemsforconstructionproductivityenhancement.Usingamultiplelinearregressionanalysis,theprocessforcalculatingthePARisdeveloped,andtheapplicabilityoftheproposedindicatorisverifiedthroughacasestudyofsteelerectionwork.TheresultsofthisstudyindicatethatthePARcanaidconstructionpractitionersinachievingmorebalancedandeffectiveproductivitymanagement,evenwhenmanagementresourcesarelimited.Keywords:productivity,productivitymanagement,reductionfactor,productivityachievementratio,regressionanalysis···································································································································································································································1.IntroductionProductivity-oneofthemajorfactorsusedinmeasuringin-dustryoutcomes-isdefinedastherelationbetweenaproductionsystemoutputandtheinputsetinthatsystem.Theimportanceofmanagingproductivityhaslongbeenemphasizedinthecon-structionindustry,andaconsiderableamountofresearchhasbeenconductedontheissue.Sumanth(1984)arguedthatbothmanagersandemployeesshouldpaycloseattentiontoproduc-tivitymanagementandthattheproductivitymanagementcyclehasfourphases:measurement,evaluation,planning,andimpro-vement,asdepictedinTable1.Therehavebeenmanyresearcheffortstoexaminepro-ductivitymeasurementandconsequentlycontributetothebetterproductivitymanagement(Heap,1987;HerbsmanandEllis,1990;ThomasandZavrški,1999).However,despiteyieldingdecentestimationsofproductivity,thesestudieshaverarelyidentifiedwhichitemsrequirethemostattentionforoptimalproductivitymanagement.Indeed,productivityhascommonlybeenestimatedbytheratiobetweensystemoutputandinputwithoutconsiderationoftheparticularsofeachworkitem.Consideringeachworkitemwhenmeasuringproductivityisacomplexprocess.Forinstance,itmustbetakenintoaccountthatworkitemsassociatedwithlowproductivitydonotalwayshavehighpotentialforimprovement.Aswell,aminimalchangeinproductivitydoesnotnecessarilysignifythepresenceofaworkitemlinkedwithapoormanagementperformance.Todealwiththesecomplexities,anadvancedproductivityindicator,whichcanaccountfortheuniquecharacteristicsofeachitem,isneeded.Forexample,Table2showsthelaborproductivityassociatedwithseveraltypesofformworkinanapartmentprojectinKorea(Jungetal.,1995).AsseeninTable2,thelaborproductivityoftheeuroform·plywoodformis0.628M2/Man·Day,whilethatoftheprefabri-catedformis0.707M2/Man·Day.However,thisfactdoesnotdirectlyindicatethattheproductivitymanagementoftheprefa-bricatedformisbetterthanthatoftheeuroform·plywoodform.Itwouldalsobeinappropriatetoconcludethattheeuroformû*Ph.D.Student,Dept.ofCivilandEnvironmentalEngineering,StanfordUniversity,CA94305,USA(E-mail:[e-mail])**Member,Professor,Dept.ofArchitecture,SeoulNationalUniversity,Seoul151-742,Korea(E-mail:[e-mail])***Member,AssociateProfessor,Dept.ofArchitecture,SeoulNationalUniversity,Seoul151-742,Korea(CorrespondingAuthor,E-mail:[e-mail])****Member,AssistantProfessor,Dept.ofArchitecturalEngineering,KwangwoonUniversity,Seoul139-701,Korea(E-mail:[e-mail])Table1.WorkinEachPhaseofProductivityCycleCycleContentsMeasurementFocusingoncalculationofproductivityvaluebymeasurer’sdefinitionandscope.EvaluationEstimatingtheamountofproductivitychangebetweentwodiscreteperiods.PlanningDevisingshortandlong-termplansinregardstofutureproductivityImprovementPerformingactualproductivityimprovementprocessusingseveralmethods.TaeWanKim,Hyun-sooLee,MoonseoPark,andJung-HoYu−24−KSCEJournalofCivilEngineeringplywoodformhashigherpotentialforimprovementthantheprefabricatedform.Instead,itmustbedeterminedwhichitemsshouldbefocusedonduringtheplanningandimprovementphasesoftheproductivitymanagementcycle.Theseitemsshouldnotbechosenmerelybyestimatingproductivitywithoutconsideringthepotentialeffectsofmanagementactivity.Althoughconversionfactorscanbeusedtoaccountfordifferentlaborresourcesandconditionsrequiredfortheoutputs(Thomasetal.,1999),theystilldonotprovideclearin