Prefabrikasyonda üretim planlamasına yönelik bilgisayar destekli bir bütünleşik veri akış/değerlendirme sistemi
A Computer-aided integrated data flow and evaluation model for production planning in prefabricated building systems
Yazar: ALAATTİN KANOĞLU
Danışman: PROF. DR. YILDIZ SEY
İstanbul Teknik Üniversitesi / Fen Bilimleri Enstitüsü / Mimarlık Ana Bilim Dalı
Derece: Doktora, 1992
Konu: Mimarlık = Architecture
Dizin: Bilgi sistemleri = Information systems ; Bina üretimi = Building production ; Prefabrike sistemler = Prefabricated systems ; Üretim planlaması = Production planning

Özet:
Giderek kontrol edilemez boyutlara ulasan nüfus artışı, düzensiz kentleşme ve plansız büyümenin neden olduğu nüfus hareketleri, diğer pek çok gelişmekte olan ülkedekine benzer biçimde, Türkiye'de de üretim, hizmet ve barınma gibi çeşitli amaçlara yönelik binaların ihtiyacı karşılamada yetersiz kalmasına neden olmuştur. Çeşitli sebeplerle tam olarak karşılanamayan ihtiyaca, konvansiyonel sistemlerle istenen süratte yanıt verilmesi ve açığın kapatılması da mümkün görülmemektedir. Prefabrike bina üretim sistemlerinin, sahip oldukları karakteristikler sayesinde sorunun çözümünde etkili olabilecek bir konumda olmalarına karşılık, gerek sürat ve gerekse maliyet açısından İstenen hedeflere ulaşmada zorlandığı da açıktır. Bunun sebeplerini, sektörün içinde bulunduğu ve kendi denetiminde olmayan ekonomik istikrarsız lığın neden olduğu kararsız ve süreksiz talep ortamında aramak kuşkusuz mümkündür. Bu koşullar altında, sistemin teknolojik yönünün yanısıra, bu teknolojinin gerektirdiği yönetimsel fonksiyonları içeren diğer boyutunun da gereken şekilde ele alınması, sorunları bütünüyle çözmese bile, önemli derecede rahatlama sağlayabilecek bir yaklaşım olacak; böylece kontrol altına alınamayan faktörlerin neden olduğu üretimsel etkinsizliklerin minimize edilmesi sağlanabilecektir. Bu çalışma, prefabrike sistemlerle bina üretiminde, söz konusu etkin- sizlikleri mümkün olabildiğince azaltmayı amaçlayan, üretim planlama sına yönelik bir Bütünleşik Veri Akis/Değerlendirme Sistemi'nin tasarımını ve ardından da sözü edilen sistemin bilgisayar destekli bir modele dönüştürülerek somutlaştırılmasını hedeflemektedir. Bu amaç la, öncelikle prefabrikasyonun endüstriyel üretim sistemlerinin bakış açısıyla incelenmesi ve farklılaşan yönlerinin saptanması söz konusu dur. Bu saptamalar, tasarlanan sistemin biçimlenişini belirleyen ana unsurları içermekte olup yönlendirici nitelik taşımaktadır. Sonuç olarak, tasarlanan sistem ve geliştirilen model, prefabrike sis temlerle bina üretimindeki iki aşamalı ve çok merkezli üretimin safhaları arasında gerekli olan koordinasyonu sağlamaya ve sürekli değişen, dinamik bir ortamda sağlıklı kararların alınmasını kolaylaştır maya yönelik biri kavramsal, diğeri nesnel, birbirini tamamlayıcı iki ayrı araç olarak ortaya konmuştur.

Abstract:
I ntroduction It is obviously seen that the progress speeds of the countries tak ing place on different points of development line differ from each other related to their location on the line. Thus, distances between the societies at right and left sides relatively reach new and uncov- erable dimensions as the time goes by. So, it can be claimed that backward countries have no way out except accelerating their de velopment process and trying to pass the phases that the others passed before as fast as possible. Today, most of the problems coming up in these countries are caused by the accidents originat ing from this kind of uncontrollable accelerations without having a plan sufficiently studied on. When we reduce the topic to the scale of building production, it is possible to observe similar problems at this level too. As an in evitable consequence of explosion of population and condensation of the investments at certain regions, great masses of people flow from one place to another. Traditional or Conventional building produc tion systems do not seem to be able to cope with the problem. Be cause they have not got required characteristics for providing the speed, which is necessary to cover the growing distance between demand and supply within a reasonable time. Finally, because of this fact, it is possible to see a number of technologies started to be used for producing the buildings required relatively in a short time and economically. Beside rationalized mould techniques, prefab ricated systems also take their places in production this way. Due to the characteristics of product and production processes, which are used conventionally, building production shows a ten dency of deviating from schedule. For this reason, especially the efforts aiming to minimize the activities on site come up as an ef fective solution, which lessen the deviations stated above. From this point of view. Prefabricated Building Production Systems have got some advantages in fastening site production by integrating various subsystems, which constitute the building structure formerly in factory. VIDetermination of Problem and Its Background After the introduction in chapter one, the concept of Prefabrication is analized in the second part of the study. This analysis showed that the notion has got two dimensions in fact; technology and man agement. In theory, technology is an important factor to increase product number in a certain period and can be defined as the basic component of prefabrication. But it is not adequate to reach the targets of production when considered alone. This can be pointed out one of the main wrongs in the countries trying to progress in that kind of an acceleration stated before. Without having a man agerial support, technology can never reach its targets in prefabri cated building production. For this reason, these two dimensions of prefabrication have got the same importance but may be technology can be qualified as "primus inter pares". Though various technologies are used within the content of prefab ricated building production systems, managerial problems and func tions are universal. As a result of this fact, the studies, which aim to reach a solution and to make the technology more efficient must be focused on this point. In chapter two, beside the technological side of prefabrication, its managerial dimension is emphasized and the problem is determined to be originated from the lack of the models responding the problems taking place at this dimension and the integrated data flow systems required by the models. Definition of Problem and Its Boundaries After determining the problem and its origin, in second chapter the managerial functions in industrial production activities are studied under the title of Production Planning and Control. Related to this stage, prefabricated building production systems are analyzed from the viewpoint of "Production Modes". Thus, the differing sides of prefabrication from the other industrial production systems are tried to be determined. It is clear that, the system, which is planned to be designed for production planning will be shaped by the charac teristics of production mode. Apart, this analysis is necessary for determining the problem and its boundaries in detail and developing a rational model to solve it. Managerial functions take place in a wide range from country to sector and company level in prefabrication as they do in other in dustrial production fields. These functions have got different con tents according to their level and term they consider. In this chapter, the qualifications and contents of these functions are also analyzed from all aspects and finally the problem is restricted by company level and short-term functions. As a result of the analysis stated above, it is seen that the features of prefabricated building production systems are shaped by three main factors. The first of these factors is related to the character- VIIistics of demand. As it is known, long-term planning is hardly pos sible especially for the countries suffering from high inflation rate and economical instability. It is too difficult for the people who are vitally in need of a house to convert their wishes into demand in economical sense in these countries. Because of these conditions, the support of central authorities can not also be continuous for providing a stable demand for building production, which is the most important factor for prefabrication. Except for the demand characteristics, the features of the product, and production processes in factory and site do not allow the stan dardization, which is one of the basic requirements of industrial production. As a result of these factors, it is not possible espe cially for the Closed Systems in prefabrication neither to maintain a "Continuous" or "Process" type production nor to estimate the de mand by time series analysis related to past. The open systems may be qualified more flexible to some extent compared to the closed ones from this point of view and may use the tools and approaches stated above for the estimation of demand and production. As for the closed systems in particular, it is not possible for these systems to apply this kind of an approach. Their production must be based on absolutely assured demands and projects. Because of this, they need detailed projects and assembly schedules for pro duction. As a result of this, their production modes can be quali fied "Custom-made" type and production planning functions must provide the demand values from the assembly schedules of contract ed projects. It is obvious that in spite of these data production plans can not be static because of the variable and unstable charac ters of either factory or site productions. In prefabrication, there are two phased and a multi-centered pro duction and these two phases have got different features. The ca pacity flexibility of factory depends on technology and production factors. As for the sites, demands of components may have differ ent values according to current number of projects and their schedules. This situation causes the factory to develop and main tain its production plans in a great difficulty. Mostly the required production speed and economical targets can not be reached and delivery programs loses their currency because of the lack of cooi - dination and sufficient data flow between production centers. Be cause of the delays of revisions in production plans, some of the components can not be produced in time while some others are pro duced unnecessarily before their delivery schedule. Consequently, the coordination and control functions of management can not be completely fulfilled and production loses its rationalism. The Aim of Study This study has got three consecutive purpose completing each other in solving the problem stated above. The first aim is to determine the modes of operations and the factors affecting them; to define VIIIthe content of Production Planning and Control Function in prefab- rication. The second aim is to develop an Integrated Data Flow and Evaluation System, which: o Integrates all the required data obtained from all production centers and provides the coordination between the two phase of prefabrication o Helps the factory to prepare the required production plans targeting to use its capacity in an optimum way o Allows these plans to be revised in a sufficient speed ac cording to real progress in both production centers. As for the third aim, it is to convert this system into an applicable and objective computer-aided model. In chapter three, the functions of the system are analyzed in detail and the components, which will constitute it are determined» The functions mentioned above can be expressed as follows: o Determination of assembly schedules o Determination of delivery schedules o Monitoring factory and site productions o Updating and revising programs o Integration of data and preparation of reports Related to these functions, the components of the system, which wil fulfill these functions are designed as follows: o Project Planning/Programming Subsystem o Building/Plan Types Definition Subsystem o Building Components Definition Subsystem o Inventory Control Subsystem o Factory Mould Definition Subsystem o Data Integration/Evaluation Subsystem Synthesis of the System and Model Project Planning/Programming Subsystem is the first component of the system aiming to prepare the work schedules of projects to which the factory serves and uses The Critical Path Method for this purpose. It makes detailed analysis about time, resources and money at the same time. The work schedules can be qualified a database and is used by Data Integration/Evaluation Subsystem in order to constitute assembly schedules. IXBuilding/Plan Type Definition Subsystem aims to make up a data base, which determines the number and types of building compo nents in all building and plan units in current projects. The sys tem uses component data-base created by Building Components Defi nition Subsystem. As for this subsystem, its aim is to prepare a database as it is stated above. In this process, all building components are defined by their physical qualifications in three consecutive level. This database is used also for constructing In ventory Control Subsystem. Inventory Control Subsystem records and saves all data about factory production and delivered amounts and types of components in project and date base. Thus it is possible for Data Integra tion/Evaluation Subsystem to compare planned and realized values and updating the assembly and delivery programs. Mould Definition Subsystem also creates a database defining the types and numbers of the moulds located in factory and determines current factory capacity in this way. The last component of the system is Data Integration and Evaluation Subsystem. This system uses all the databases created by other subsystems and produce a wide range of reports, which have got different contents according to different purposes. The system integrates all data obtained from project work schedules, sorts the data related to assembly activities and by combining building/plan type data-base and the schedule of assembly activities prepares assembly and delivery programs for ev ery building component type. The system structured in chapter three is converted into a com puter-aided model then. In chapter four, the principles and compo nents of the model and the relations between these components are defined. The outputs of the model are also given in appendices at the end of the study. Conclusions Prefabricated Building Production Systems may compete the other systems which are still in use widely if they can stay under the cost limits. For this reason, they need managerial tools and methods supporting their technological advantages for obtaining productivity and effectiveness required. In this study, the general principles of this kind a tool are de scribed at first stage. In second stage, a computer-aided model which aims to integrate and evaluate the data and to create the re ports for production planning in prefabrication is developed by converting the system stated before. The third point carrying originality in the study is the evaluation of prefabrication from the viewpoint of industrial production systems which is necessary for developing the tool explained above.