[Systems Engineering] #2. Definition of System

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One day after lunch, when the time off from work felt particularly long, I suddenly asked my friends a question via Social Network Service.

‘What do you think of when you hear the word ‘system’?’

Friends’ answers varied:

“Things work well no matter who does it or in any environment.”

“When we do or use something, a program that helps us do it well.”

“A processing method to produce results suitable for a specific purpose. It can be done by a person or a machine, but it produces results efficiently.”

“It feels too difficult, broad and arcane.”

“An abstract word that contains the components and functional processes of something.”

“Are you sleepy??”

Each answer interpreted the definition of system from a different perspective.

Recently, while working as a systems engineer in the automotive electronics industry, I decided to start a blog. The topic I wanted to cover first was ‘What is a system?’

I myself work as a systems engineer, but it was harder than I thought to give an easy and clear answer to the question, ‘What exactly is a system?’

I was thinking of starting with ‘This is what a system is…’, but it wasn’t easy to give an accurate definition.

After thinking about this, I decided to ask ChatGPT this question. What about ChatGPT’s answer? Let’s find out together through this post.

A system is like a large ‘group’ where many parts come together and work together.

These parts help and rely on each other, working together to achieve a goal.

For example,

Dennis Bergkamp coaching kids at Ajax youth team
Dennis Bergkamp coaching kids at Ajax youth team

Taking a soccer team as an example, there are players in various positions, including goalkeeper, defender, midfielder, and attacker.

Each of them has a different role, but they all work together to try to win the game. Here, the soccer team becomes the ‘system.’

As a second example, we can consider a school as an example of a social system.

A school is a system comprised of a collection of rules that govern the behavior of teachers, students, and people (class times, recess times, meal times, etiquette, etc.) and educational facilities such as school buildings, classrooms, and gymnasiums.

Finally, examples include technological systems such as computers or smartphones. These devices work by having multiple programs or apps exchange information with each other. For example, a smartphone can show friends’ news and send and receive messages through the Facebook app. These various programs and functions come together to form the ‘system’ called a smartphone.

In conclusion, definition of system is a system in which many parts come together to help and cooperate with each other to achieve one big goal. This system may be as simple as a sports team, as complex as a school or society, or it may consist of technological devices such as computers or smartphones.

A system is a combination of interacting elements to achieve a defined goal. And these elements include hardware, software, firmware, personnel, information, technology, facilities, services and other support elements.

International Conference on Systems Engineering (INCOSE 2015) Handbook

For your reference, you can access Systems Engineering Handbook v4 through the link below.


Based on the example above, let us summarize the important characteristics of the system and additional characteristics that can be derived from them. From a systems engineering perspective, understanding these characteristics is critical to the design and management of systems.

Default system characteristics:

  1. Set of elements: A system consists of a set of various elements, and these elements must be at least two.
  2. Interaction: Each element of the system must interact with each other, and elements that do not interact are not components of the system.
  3. GoalAchievement: The interaction of elements determines the behavior of the system. And through these actions, the goals of the system are achieved.
  4. Achieving a goal in a specific environment: The system achieves a defined goal in a specific environment or context.

Additional System Features:

  1. System Boundary: The system boundary is a boundary that includes the components of the system and their interactions, and separates the system from the external environment. System boundaries clarify the responsibilities and management scope of the system. For example, in an automobile electrical system, the electronic system inside the vehicle is included within the boundary, and the external environment (road, weather conditions, etc.) is located outside the boundary.
  2. System Behavior: It is the behavior of a system that appears through the interaction of elements within the system, and has complex characteristics (emergent properties) that arise from interactions rather than a simple sum of individual elements.
  3. Emergent Properties: Emergence means that the behavior of the system creates new properties or functions beyond the independent functions of each element. This results from the complex interactions of the system. For example, a car’s engine management system, navigation, and safety systems do not operate independently, but their interaction determines the overall performance and safety of the vehicle.
  4. System Context: Includes the environment in which the system is located and describes interactions between the system and external elements. This helps identify factors external to the system and understand how the system performs within its environment.

These characteristics serve as key elements in the design, analysis, and management of systems in systems engineering. Each characteristic provides a basis for understanding the system more clearly and managing it effectively.

Based on the above explanation, let us rearrange the characteristics of the system. In systems engineering, understanding these characteristics plays an important role in the design, operation, and maintenance of systems.

  1. Goals and Functions: The system has specific goals (Goals, Objectives) or functions (Features). This means that the system exists to achieve a specific purpose.
  2. Various Components: A system is made up of multiple components (System Elements), including devices, methods, procedures, and, in some cases, humans, that play various roles.
  3. Integrated Operation: Each component performs a unique function and their interaction forms an integrated system. This means that goals that cannot be achieved by individual elements can be achieved as a whole system (System Behavior). (Emergent Properties)
  4. Input and Output: The system receives input from the outside and creates output that meets the goal through organized processing (Process, System Behavior).
  5. Hierarchical structure: The system has a hierarchical structure, and the inside is called the ‘system’ and the outside is called the ‘environment’ based on the system boundary. A larger system (System of Systems) may be composed of several subsystems.
  6. Self-regulating ability: The system is self-controlled. Establish an internal control mechanism (feedback) to prevent deviation from established rules, limits, and tracks.

These characteristics are essential for understanding, designing, and managing systems effectively. Considering the complexity and interactions of the system, these concepts become important criteria for the successful implementation and operation of the system.

As I thought about the concept of system in detail, its meaning began to become clearer.

However, as time passes, the word ‘system’ may feel ambiguous again. So, to make it easier to understand, we have organized the definition of the system into key keywords.

  1. Goal, Objectives:
    • Systems exist to achieve or provide a specific purpose or function. It represents the functional aspects of the system and the goals to be achieved.
  2. System Elements:
    • A system is a collection of several independent elements. These elements form the basic building blocks of the system.
  3. System Behavior:
    • Interactions between system elements represent the dynamic behavior of the system. This is important to enable the functionality and capabilities of the system. They can be viewed as dynamic emergent properties.
  4. System Properties:
    • Interactions between system elements create static properties of the system. It defines the overall characteristics and nature of the system. It can be viewed as a static emergent property.
  5. System Boundary:
    • The system boundary separates the inside and outside of the system. This helps clearly define the scope and responsibilities of the system.
  6. System Context:
    • Indicates the environment in which the system is located and operates. It involves interactions between the system and external factors.
  7. Feedback Mechanism:
    • The system has self-regulating capabilities, which are implemented through internal feedback mechanisms. This helps the system function in a stable and predictable manner.

These keywords provide important guidance in understanding and designing systems. These are essential elements for understanding the complexity of the system and effectively managing and integrating each element and function of the system.

To help you understand more clearly, let’s apply the seven elements defined above to three examples. The example below may not be accurate because I wrote it after thinking about it myself, but it will be of some help in understanding the concept of the system.

Example 1: Soccer team system

  • Goal, Objectives: Win the soccer game
  • System Elements: Players in various positions such as goalkeeper, defender, midfielder, attacker, etc.
  • System Behavior: Scoring a goal into the opponent’s goal through strategic play
  • System Properties: Team morale, teamwork
  • System Boundary: Our team (including manager and coach)
  • System Context: Soccer stadium, opponent, weather, etc.
  • Feedback Mechanism: Director or coach’s instructions, tactical changes, etc.

Example 2: School system

  • Goal, Objectives: Raising children into desirable human beings
  • System Elements: Teacher, various rules, classes, after-school activities, curriculum, school building, etc.
  • System Behavior: Creating a good school
  • System Properties: High school ranking, academic atmosphere
  • System Boundary: School
  • System Context: Parents, local education policy, school surrounding environment, etc.
  • Feedback Mechanism: Discipline or evaluation score

Example 3: SNS system on smartphone

  • Goal, Objectives: Communicate with friends remotely.
  • System Elements: Kakao Talk, Display, Wireless, CPU, Memory, Android, etc.
  • System Behavior: Send the entered message to your friend, receive the message sent by your friend on your smartphone
  • System Properties: User Experience (UX), message sending/receiving speed, etc.
  • System Boundary: Smartphone
  • System Context: Smartphone, user, friend, repeater, telecommunication company, etc.
  • Feedback Mechanism: Mechanism where Android or IOS kills the app when it is extended.

When I try to describe each example above in a way that fits the system definition, there are parts where I get stuck.

For example, the parts about System Behavior and System Properties, which are emergent characteristics, were difficult to write, probably because I did not have domain knowledge about each of the examples above.

For reference, System Behavior and Properties were written by considering the system itself as a black box and considering the functions provided by each system and the characteristics of the system as a whole.

So, what is a system in the automotive electronics field, which is the core topic of this blog?

It is expected that most readers of this article are working in embedded system development at electronics companies. And what we are developing is an embedded ‘system’.

Dictionarily, an embedded system is defined as ‘an electronic control system that combines computer hardware and software to perform a specific function.’ The embedded system we develop can be analyzed as follows.

  1. Goal, Objectives: Embedded systems exist to provide specific services or achieve goals. This represents the core functionality that the system must provide.
  2. System Elements: The system consists of software, hardware, mechanical components, etc. Each element performs a specific function, and their integration implements the functionality of the overall system.
  3. System Behavior: Indicates the dynamic capabilities of the system. It explains how an embedded system works and how its elements interact to achieve overall functionality.
  4. System Properties: Refers to the static properties of a system, which indicate the overall characteristics and performance of the system.
  5. System Boundary: Define the scope of development. This is based on the development requirements received from the customer.
  6. System Context: Includes the external environment with which the embedded system interacts. It describes the relationships and interactions between the system and external elements.
  7. Feedback Mechanism: Refers to internal control mechanisms such as failure handling. This ensures that the system operates predictably and reliably.

In order to properly develop the system to be developed through these concepts, the following information is required.

  1. System Features: Clearly define the services the system must provide or the goals it must achieve. This determines the main functions and roles of the system.
  2. System Context: Includes the environment in which the system operates and describes the interactions between the system and external factors. This is important to understand external influences on the system.
  3. System Boundary: Define the scope and responsibilities of the system. Distinguish between the internal components of a system and its external environment.
  4. External Interfaces: Define the inputs and outputs of the system. It clarifies the interaction between the system and external systems or the environment.
  5. Item Level Functional Requirements: Specifies the specific functions the system must perform. It defines how the system should work.
  6. Item Level Non-Functional Requirements: Specifies non-functional characteristics of the system, such as performance, stability, security, etc. This includes requirements related to the quality of the system.
  7. Preliminary Architecture: Design the basic components of the system and the relationships between them. This determines the overall structure of the system.
  8. Feedback Mechanism: Define the control and regulation mechanisms within the system. (e.g. Fail-Safe Logic) This ensures stable operation of the system and prevents potential problems in advance.

As experienced practitioners will already know, the core elements of the aforementioned systems usually need to be included in Customer Sourcing Requirements (CSR).

However, in most cases, customers do not provide this information accurately. Therefore, before writing a system requirements document, we need to request this information from the customer or use the relevant domain knowledge to clearly define the system we want to develop. I believe that the process of obtaining customer approval for the subsequently written system requirements (SR) is very important.

We often neglect the process of defining the system we are developing. However, based on the experience I have gained while working on systems in the automotive industry over the past eight years, it is no exaggeration to say that the success of the later stages of a project is determined by how accurately the system is defined before developing system requirements.

Additionally, as a systems engineer, accurate system definition is essential to engage in meaningful design activities and develop system design capabilities. If design activities are performed without proper definition, the system being designed becomes ambiguous, making effective evaluation of the activities performed difficult. This can result in less gain for a lot of effort.

I hope that this article, definition of system, and all future articles, will be helpful to my fellow colleagues who are starting their careers as systems engineers in the automotive electronics industry. I am also not an expert in the systems engineering field, and I am accumulating experience and knowledge through practical work. There may be incorrect information in my post, so if you have a different opinion, or if you agree with my post and want additional attention, please actively leave a comment.

This blog aims to provide information to help make the lives of systems engineers working in the electronics industry better and better.

In the next article, I will share my thoughts on ‘Systems Thinking.’

[Systems Engineering] #1. INTRODUCTION – Navigating Systems Engineering

[Systems Engineering] #2. Definition of System

[Systems Engineering] #3. Understanding Systems Thinking

[Systems Engineering] #4. Useful knowledge of systems thinking

[Systems Engineering] #5. Understanding Systems engineering

[Systems Engineering] #6. Who is Systems Engineer

[Systems Engineering] #7. Understanding MBSE (Model Based Systems Engineering)

[Systems Engineering] #8. Additional practical knowledge about MBSE

[Systems Engineering] #9. What is Good System Model?

[Systems Engineering] #10. Understanding SysML (System Modeling Language)

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