The hardware and software benefited in this project are the physical mailbox itself, a microcontroller, infrared sensors, and MySQL database management system. This chapter will give brief introduction of the mailbox and postal system, fundamental of microcontroller and sensor, and database management system (DBMS).
2.2 Mailbox and Postal System
2.2.1 Introduction of Mailbox
Mailboxes are tools for sending letters (Postbox Solutions, 2007). They are very common in human communities. It provides people with one of the most practical way of communicating with other people around the world. There are so many varieties of mailbox regardless of shapes, colours, fonts, logo and etc. However, no matter how different or how strange the mailbox may look like, it still does its job with no compromises.
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2.2.2 Relationship of Mailbox and Postal System in History
Research by Cornerstone (2010) said that mailboxes is started to be used in the late 1700s in Paris, France. As time passed by, it became popular in the Europe in middle-late 1800s after the British Post Office asked people to install mailboxes at their offices and residents and decided to begin mail delivery. Previously, people have to pick their mails at the local post office by themselves and there were no postmen during that time.
The story is different in the U.S in 1863 when the U.S. Postal Service (USPS) began the Free City Delivery. People in the U.S at that time had no mailboxes installed at their houses. Postmen delivered mail to each houses door by door waiting for a patron to answer the knock. This method of mail delivery took extra time and patrons were not always home or able to answer the door. Patrons began to install mail slots and mailboxes at their doors.
According to Cornerstone (2010), the U.S. Postal Service in 1896 introduced Rural Free Delivery (RFD). The USPS researched ways to save time and solve the problem with mail-carriers delivering mail to the scattered rural patrons. They proposed that mailboxes for people lives in the area to be placed at curb sides and roadways. Later in 1923, USPS mandated that every household to have a proper mailbox to receive mails.
In 1915, Roy J. Joroleman, an employee of the post office invented the curved, tunnel-shaped mailbox. The shaped was designed to prevent water and snow from collecting in the mailbox. Soon after, the Postmaster General released the design for manufacture and production and this design has been the top-selling type of mailbox (Cornerstone, 2010).
Figure 2.1 : A curved, tunnel-shaped mailbox
2.2.3 Centralize Mailbox System
The development of the country has seen that there are so many tall, multiple-storey building been built all over the country. Single type mailbox that can always be spotted at each household and offices during the early days is no more practical for residential apartments and office complexes. In order to overcome this problem, centralize mailbox system was introduced. Centralized mailbox system often found at the ground floor of each tall building where every owner of each residential apartment or office will have one for his or her unit.
Figure 2.2 : Centralize mailbox system.
2.3.1 Introduction to Microcontroller
In simple words, a microcontroller is a computer (Brain, 2000). The terms “computer” can be wide in definition. It can be a desktop personal computer, a laptop computer, a handheld-sized smartphones or the microcontrollers themselves. A microcontroller can be interpreted as a computer due to the reason that it has several similarities as compared to a computer.
Generally, the basic architecture of a microcontroller involves four main parts; central processing unit (CPU), random access memory (RAM), read-only memory (ROM), and input output ports (I/O ports). In the case of computers, all computers have a CPU that executes programmes such as a web browser or a word processor. The computer has some RAM installed where the CPU can store variables while doing its work. It also has I/O ports that connect many types of input and output devices, for example the keyboard – the input device, and the monitor – the output device.
inside a microcontroller.PNG
Figure 2.3 : The architecture of a microcontroller (Engineers Garage).
However, with certain comparison in terms of features, microcontrollers and computers can be differentiated. The desktop computer which often can be found at offices and homes is a general purpose computer, while a microcontroller is a special purpose computer (Brain, 2000). Due to its relatively small size, microcontrollers are embedded inside some other devices and work as the controller of the features of the product. Microcontrollers are also dedicated to run one specific programme only; the programmed that is loaded into the ROM. Finally, often in most of the cases, a microcontroller is small and low in cost, hence good for mass production of products that utilize microcontrollers.
2.4.1 Introduction to Sensor
A sensor is a device that measures the physical quantity and converts it into a signal which can be read by an observer or an instrument. Ideal sensors are designed to be linear. The output signal of such a sensor is linearly proportional to the value of the measured property. The sensitivity is then defined as the ratio between output signal and measured property. A good sensor obeys the following rules:
Is sensitive to the measured property.
Is insensitive to any other property.
Does not influence the measured property.
2.4.2 Applications of Sensor
Sensors are widely used in our daily life nowadays. There are many types of sensors today. These sensors can be categorized into specific types. Lists of sensors use nowadays are as below:
Acoustic sensor such as Geophone, Microphone and Seismometer.
Electric current sensor such as Ammeter, Voltmeter and Multimeter.
Environment and weather sensor such as Gas detector and Rain sensor.
Optical, light and imaging sensor such as flame detector, Infra-red sensor and Photodiode.
Pressure sensor such as Barometer, Hydrometer and Pressure sensor.
Temperature sensor such as Thermometer.
2.5.1 Introduction to Database
The database is one of the technology terms that most people have become accustomed to hearing either at work or while surfing the internet. The “database” term used to be an extremely technical term. However, database has become a household term with the rise of computer systems and information technology throughout the culture.
Selena (1998) has highlighted the definition of database as a computerized way of keeping collection of records or data. The true usefulness of database is seen especially if the data stored in the database in big volumes because the stored data is easily accessible. Moreover, adding new information and updating any changes should also be considerably painless. Besides that, on-demand record searching in the future will be piece of cake. Another advantage of a database is it can be shared all over the network where the computer that holds the database is connected.
At this point, the presence of a Database Management System (DBMS) is very important in order to have a highly systematic database system. DBMS is a program that handles the queries and data stored inside the database.
2.5.2 Types of Databases
There are four types of databases that are commonly used where each type of database represents its own data model. Data model means how the data inside the database is structured. The four types are; Flat Model, Hierarchical Model, Relational Model, and Network Model.
188.8.131.52 The Flat Model Database
As written by Smith (2010), a flat database is a database that utilizes only one table for the fields of records. For example, a spreadsheet is used to store all the data and records. The information is separated into columns of its category, and each line represents one record. This type of database might be sufficient for small database, but a spreadsheet will seem to be not practical, notably for ones with large amount of records.
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184.108.40.206 The Hierarchical Model Database
As its name hints, the hierarchical model database resembles a hierarchically-arranged data (Selena, Introduction to Databases for the Web: Pt. 1, 1998). It links records together in a structure like a tree, or like an organizational chart. In this model, each data will be categorized and stored as a sub-data of its category. Every data must fall into only one category. Hierarchical structure database were widely implemented during the early time of database management systems. However, this model of database became irrelevant for some certain data types. For example, in a college environment, the administration might stored student information and sorts them according to their courses. Database operation will be smooth if every student is enrolled in one course only. But, problem will arise whenever a student enrolled in more than one course. Hierarchical database is unable to put a record into two categories, or otherwise, it will be considered as duplications. Figure 2.4 shows an example of the structure of hierarchical database.
Figure 2.4 : The tree structure of hierarchical database model.
220.127.116.11 The Relational Model Database
The relational model is the most popular type of database the most database system in use today. As appointed by K. Powell (2010), the relational database concept was derived from the principal of relational algebra, which was realized by Dr. E. F. Codd in his paper, A Relational Model of Data for Large Shared Data Banks. This database model is a very powerful tool, not only to store records, but to access it as well. All the data were stored in tables. Each table contains of rows and columns. A single record will be recorded in one row, and the details of the data are separated in columns, in the table. Every column has a unique name and the content within the column must be of the same type. A table is able to hold many records, and sometimes tables are referred as relation.
A database may have more than one table. Each of the tables can be linked or related to each other by referring to the primary key. A primary key is a unique name that every record must have that acts as its identifier.
18.104.22.168 The Network Model Database
A network database model is not far different from the hierarchical model. The difference between network and hierarchical model is, in network model, a record may fall into more than one category. Figure 2.5 shows the structure of network database model which is a bit different from relational database model’s.
Figure 2.5 : The structure of network database model.
2.6.1 Introduction to MySQL
MySQL is a probably the most popular database management system. Referring to the MySQL 5.0 Reference Manual (2010), to perform an operation onto a database such as adding, accessing, and processing data stored in a computer database, ones will need a database management system such as MySQL. A DBMS plays a central role in computers at handling large amounts of data.
Figure 2.6 : The MySQL logo.
MySQL is a relational database management system or so called as RDBMS. For the sake of speed and flexibility, a relational database stores data in separate tables compared to flat file database that puts all the data in one big file. The SQL abbreviation in “MySQL” word stands for “Structured Query Language” (MySQL 5.0 Reference Manual, 2010).
Badurina (2010) stated that MySQL is open source and it falls under GNU Not Unix (GNU) General Public License (GPL). Open source means that anyone is possible to use and modify the software.
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