1. Introduction
A smart city may be considered an advanced concept related to the concepts of the information city, digital city, intelligent city, and sustainable city [
1,
2], and has been widely cited and studied, along with the sustainable city concept, since 2013 [
3,
4]. According to Google trends regarding the “smart city” (accessed on 13 March 2019) (
Figure 1), the smart city’s search terms have been on the rise since 2004 and peaked in 2015, but have remained high, suggesting many studies and discussions are occurring on the smart city concept [
4,
5]. However, the concept of a smart city is controversial, and no exact agreement has been reached on its definition. Despite efforts to conceptualize the smart city in many research fields and studies, most definitions of the smart city have been ambiguous or duplicated [
3,
6]. For example, many studies have used smart city, smart sustainable city, sustainable smart city, and so on interchangeably. These terms need to be clearer because they have the potential to be confused with specific and related terms, often interactively used by policymakers, planners, and researchers, when considering the common aspects of urban sustainability [
3]. It is not yet possible to establish a comprehensive approach that addresses the various dimensions of sustainability at the urban level [
7]. However, in general, the smart city is understood as an ideal model for urban planning and development, adaption to environmental issues such as climate change and global warming, and efficiently utilizing and managing energy. In addition, Information and Communication Technologies (hereafter ICT) will extensively and effectively help cities achieve a comparative edge [
4,
8,
9], and be used as the tools and means to develop Intelligent Transport Systems (hereafter ITS) with mobility information and the Internet of Things (hereafter IoT) [
10,
11,
12], as well as to achieve urban policy making based on governance and open data [
13,
14,
15]. Accordingly, in improving the urban quality of future urban areas, the term smart city is considered as an umbrella concept that includes various sub-concepts such as sustainable smart environments, smart technology, smart energy, smart transportation, smart mobility, and smart government [
16,
17,
18,
19,
20,
21].
The concept of the smart city has emerged over the past decade through ideas of ways to improve the functioning, efficiency, and competitiveness of cities, and solve their environmental challenges. Early on, it was speculated that ICT would play a key role in the smart city [
22,
23,
24]. With the development of ICT, the functions of urban management were improved in various fields, such as transportation, energy, health care, and water [
2], and the use of ICT facilitated the development and delivering of information and knowledge generated in daily life, promoting citizens’ participation in e-governance and e-services [
25]. Additionally, ICT is a technical platform for the process of collecting and processing massive amounts of data, called big data, enhancing digital devices, Internet services, the IoT, and the Internet of people’s societies [
25], and these techniques and technologies have been recognized as tools of urban planning to create innovative, intelligent spaces and improve urban sustainability [
26]. In this way, the information gathered by these processes is accelerated to achieve intelligence and efficiency in managing urban resources and settings [
27,
28,
29]. Collectively, ICT-based predictive analytics can demonstrate the best implements for gaining insight into data for future decisions [
30,
31], and enhance the outcomes for other stakeholders in the smart city area [
2].
A new and important flow in ICT is the identification and utilization of meaningful data collected from information systems [
32], and the analysis of the data in various applications in smart cities [
33]. ICT is being spotlighted in urban planning as one of the key components of the urban infrastructure that enables access to a smart city [
34], and the smart city concept relies on the IoT technology’s visions of pervasive computing and related big data applications [
20,
35]. Many process technologies have been introduced to understand and analyze a lot of the information connected to the IoT, among them data mining which is one of the most valuable technologies [
36]. Technological and technical advancements in ubiquitous computing, wireless sensor networks, cloud computing, and machine learning have adopted by big data analytics as supporting tools [
37,
38,
39]. Moreover, smart devices share their own information and access with other devices, and generate information with internal applications by themselves [
40]. Through these computing and ICT processes as core enabling technologies, the information is used for understanding, analyzing, evaluating, and monitoring, and this contributes towards the goals of sustainable development in the sustainable city [
35]. Predictions and outcomes analyzed from information gathered through ICT may be efficiently reflected in various aspects within urban areas, and help the decision-making process in urban service policies, such as those around the environment, education, and well-being. In light of this, ICT is deeply involved in the need for smart, data-centric technologies for dynamic and evolving urban plan systems aiming towards sustainability for the management and development of urban functions [
35,
36,
37,
38,
39,
40,
41].
The concept of the smart city with advanced technologies is not certainly complete to achieve optimal sustainability in urban development and planning yet [
20,
42,
43]. However, ICT analytics, including big data, are considered to be fundamental ingredients for urban analyses [
20,
42,
43]. In addition, ICT is being considered to achieve long-term goals of sustainable development, as a way to mitigate increasing social-economic concerns and complex environmental challenges in modern cities in their various forms of sustainability, infrastructure, data analysis, and services [
20,
23]. The applicability of smart systems in contemporary cities requires the comprehensive understanding of the possibilities of how unpredictable and unprecedented urban issues, such as population growth, environmental pressure, and human welfare and safety, can be efficiently handled [
41,
44]. In this regard, the Smarter Cites Challenge program of IBM achieved smart city projects in 100 cities around the world, with essential themes for urban management such as urban planning, transportation, environment, civic engagement and civil management, and public safety [
45]. Its program has helped global cities to significantly improve quality of life through data analytics [
46]. Huawei, a technologies company in China, published a report in 2017 comparing the 20 cities in the United Kingdom in detail, with themes such as digital innovation, social management, urban mobility, energy education, and sustainability, to address challenges facing cities and communities moving towards strategic smart cities [
47].
Cities are absolutely required in the process of urban planning; utilizing their infrastructure and technologies, and cooperation from citizens, will be needed in order to approach the optimal smart city, because the ultimate goals of urban planning based on sustainable development are to improve the quality of life of citizens [
48]. Citizens are deeply involved in urban initiatives and governance, and contribute to disseminating smart devices and Internet sharing, and generating information [
49]. In implementing smart city projects, citizens should be considered as important decision makers, with their priorities for the strategies and goals to be understood as relating to the needs and challenges in their own city; the government should support their initiatives and governance [
50]. In fact, a study supported by the EU reviewed 300 initiatives in smart cities and the community highlighted that governance, which consist of citizens, government agencies, private companies, and investors, should be important in the processes of resolving problems and making policy decisions [
51]. The positive effect of governance frameworks based on citizens, companies, and governments should not be understated in smart urban planning, and smart governance frameworks that are established must be credible to community members, stakeholders, and experts.
While various indicators of urban functions and development have been used, few studies have indicators for assessing the smart city [
52]. At a time when the definition of perfection is not yet agreed upon, the assessments of smart cities have been conducted differently in the ICT-centered approach and the people-centered approach [
53]. Moreover, the form, size, and funds for each city are considered priorities as fundamental dimensions; small cites are not guaranteed to have an effective understanding of innovative strategies, and smart strategies should be harmonized with government policies [
9]. In this regard, the reflection of smart strategies should require a considerate approach depending on the degree of urban development, the latest technologies, and the composition frameworks of governance with the community [
54].
In light of the above, smart cities have the potential to provide better urban services to urbanities than urban planning in the past. Existing cities would be applicated by the smart systems as they become accustomed to new technologies that trigger a new paradigm shift in urban planning. Many cities around the world are considering approaches to achieve sustainability in their respective urban environments. Smart concepts are not inherent to the building of cities, but should be considered as the root of a big urban concept. Therefore, cooperation in various research fields is required to address challenges arising in real time based on ICT, utilize data, and reflect this in urban planning. However, few studies have been performed in collaboration or in joint study with other research fields on the actual application of smart functions. Most of the literature is on the advanced technology of urban planning, focusing only on specified fields such as transportation, building, and energy, where ICT was applied to existing cities to emphasize a new city brand [
55]. Others have noted that an effective smart policy is required to develop suitable infrastructure, along with governance by a watchdog and collaborator through public–private partnerships [
5,
9,
56]. However, a smart city cannot be led by just any organization or government, nor can it be achieved in one study area.
Understanding the smart city based on the literature requires identifying the concepts of the evolving process of urban planning. In particular, we attempt to highlight a new, feasible urban planning system based on the smart concept with other studies areas, and identify the flow of the application of smart systems in other research areas. However, most of the studies on smart trends so far are qualitative research projects. Quantitative and comprehensive research is required to adapt to rapidly evolving cities. We aimed to comprehend how the smart concept can be applied to urban planning. This paper provides the flow of the smart city and connection of other study areas, in terms of urban policies.
6. Conclusions
The smart city has been regarded as an ideal city for solving the challenges that have arisen in various fields, such as the environment, energy, and transportation, within existing cities. However, many scholars and papers have questioned the difference between a smart city and a sustainable city, the latter of which many cities in the world have been pursuing. In order to introduce the concept of a smart city, various questions around the challenges to be reconciled have first been addressed as an agenda in international society. This is a result of the unclear definition and concept of the smart city, and it is necessary to grasp and understand the flow of research that has been carried out so far, because the smart city is related to various urban elements. Therefore, this study analyzed the comprehensive flow of the smart city, using keywords of papers that have been published so far.
Smart cities, which have been heavily researched for conceptual introduction in the past, are increasingly being studied in terms of sustainable urban planning. In particular, with advanced ICT, much research is being carried out on the utilization aspects of big data. However, because the research fields of the smart city concept are wide and diverse, it requires governance based on communication and cooperation of citizens, governments, stakeholders and private companies. All must think together to promote higher urban services, and should work hard to apply smart concepts that are appropriate for each city.
Besides, the fact that more conference papers than articles exist in this area indirectly suggests that more research is still needed. This would enable the interpretation, discussion, and exchange of information on individual studies at conferences, as the studies which have been carried out so far are limited in their comprehensive application to urban areas. This process will contribute to smart city projects and papers of high quality in the future.
The limitations of our study were that, while keyword analysis was useful for overall flow understanding and quantitative analysis, it may not represent the whole content because it relies on keywords in the analysis process. What the authors wanted to express in each paper might not be used as keywords, and there was a possibility that the smart city concept was used as a trend-sensitive keyword. If the composition of the keywords does not represent the author’s paper, the analysis results are likely to be misinterpreted. Second, the keywords that had important meaning in each paper are collected and analyzed, but the results were not compared to review papers written through other qualitative methods. If the relationship between keywords is unclear, or there is no connection point, the interpretation of the analysis results might be incorrect or misinterpreted.
We propose two studies of keyword analysis in future research. The first involves a comparative analysis of keywords in papers on how smart concepts play a role in devolved and developing countries undertaking new urban planning. By analyzing developed countries, the results would propose processes that are first required for developing countries, and by analyzing developing countries, the results provide an important guideline for cities that will apply smart concepts in the future. The second is to select specific cities as the study areas, collect keywords relating to the smart city from web-based big data, and analyze how smart concepts are being utilized within urban areas. These results will also be a good guideline for cities that consider smart concepts in new urban planning.