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Amid a plethora of challenges, technological advances in science and engineering are inadvertently affecting an increased spectrum of today's modern life. Yet for all supplied products and services provided, robustness of processes, methods, and techniques is regarded as a major player in promoting safety. This book on systems reliability, which equally includes maintenance-related policies, presents fundamental reliability concepts that are applied in a number of industrial cases. Furthermore, to alleviate potential cost and time-specific bottlenecks, software engineering and systems engineering incorporate approximation models, also referred to as meta-processes, or surrogate models to reproduce a predefined set of problems aimed at enhancing safety, while minimizing detrimental outcomes to society and the environment.

ISBN 978-1-78923-951-5

Reliability and Maintenance - an Overview of Cases

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**1. Introduction**

Different cardiovascular exercises that can be practiced in everyday life, such as swimming, walking, running, cycling, and mountain climbing, improve oxygen transfer to each body cell [1]. In addition, it positively affects neurological and cognitive function in all ages, from children to the elderly [2]. Since regular exercise has been steadily reported to improve brain function in various age groups, adolescence, the most active period for nerve production and cell connection, is a critical moment to enhance cognitive function by participating in the exercise [3].

Physical activity during adolescence positively affects the brain's readiness to accept new information, improving learning memory [4] and optimizing the mental environment to increase alertness and concentration [5]. Marsh and Kleitman [6] noted that healthy children generally have better learning skills than their counterparts. Furthermore, children who practiced regular exercise also had higher memory skills and academic achievement [7]. Hence, it is well documented that adolescent exercise improves the brain's structure by supplying blood to the brain and further improves academic ability while functioning to make the brain's state optimal [8].

One interesting topic among the various studies of adolescent exercise participation is related to morning exercise. For example, a recent study revealed that routine morning exercise improved the health and weight management of the overweight population [9]. Moreover, McGowan et al. [10] suggested that completion of a morning swimming session with resistance exercise can substantially enhance sprint-swimming performance completed later the same day. In this respect, morning exercise can draw academic significance in

**Citation:** Choi, W.; Jeon, W. A Study on the Subjectivity of Parents Regarding "0th-Period Physical Education Class" of Middle Schools in Korea Using Q-Methodology. *Int. J. Environ. Res. Public Health* **2022**, *19*, 7760. https://doi.org/10.3390/ ijerph19137760

Academic Editors: Paul B. Tchounwou, Clemens Drenowatz and Klaus Greier

Received: 27 May 2022 Accepted: 21 June 2022 Published: 24 June 2022

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**Copyright:** © 2022 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https:// creativecommons.org/licenses/by/ 4.0/).

studies targeting adolescents. For instance, consistent morning exercise participation, such as swimming in adolescents, positively affects the sleep–wake cycle [11]. In addition, Babadi et al. [12] observed that adolescents who engaged in morning exercise at school had a lower prevalence of hypertension. At the same time, the other group who spent more time on sedentary activities were at higher risk for hypertension.

A project attempted to prove the effectiveness of such early morning exercise related to academic achievement. The study showed that early morning exercise with moderate to vigorous intensity optimizes students' brain function, attentional control skills, and learning attitude [13]. In 2010, the project leader, Dr. John Lately, was invited as a guest lecturer in Korea to introduce his findings and emphasize early morning exercise in the school system. Since then, the early morning exercise program has been implemented at the public schools in the country and was named "0th-period physical activity" or "0thperiod physical education class" [14]. Recently, the term "0th-period physical education class (0th-period PE class)" has been generally accepted for autonomous physical activity sessions (i.e., 7:30~8:30 a.m.) before the official class begins [15].

Various studies on "0th-period PE class" have been conducted in Korea, and Jeon et al. [15] found that the participation of middle school students had a statistically significant effect on perceived enjoyment and learning attitudes. Furthermore, an intervention study at the elementary school also concluded that the early morning exercise program significantly improves social skills, autonomy, and stability [16]. Finally, for the high school case, a 3-year long-term morning exercise program positively influenced participants' fitness test scores, physical self-concept, and academic achievement [17].

Although many studies showed positive results of adolescent morning exercise programs, parents' involvement and perception are not well documented yet. In general, parental involvement in a child's education is consistently found to be positively associated with a child's academic performance [18]. However, Lim et al. [19] pointed out that excessive parental obsession with their children's academic achievement might harm the expansion of "0th-period PE class". Furthermore, Jeon et al. [20] stressed that parents' perceptions should also be further investigated, noting that there will be great differences between middle school students' perceptions and parents' perceptions in participation in "0th-period PE class". In this respect, the Q methodology could be used as one of the prominent ways to reveal other social perspectives that exist on issues or topics related to physical activity [21]. Therefore, considering the parental influence on adolescents, investigating and analyzing parents' perceptions and demands is of great importance for successfully settling the "0th-period PE class". The results of this study will contribute to grasping parents' perspectives in exploring improvements in morning exercise programs and presenting policy directions for future program expansion.

Consequently, the current study examined the parental perception of a morning exercise program for adolescents to provide ideas and agendas for successfully implementing "0th-period PE class" in the country. Two research questions guided the methodology and data analysis. First, using the Q-methodology, how are parents' perceptions of the "0th-period PE class" categorized? Second, what are the characteristics of each type, and what are the differences, commonalities, and implications?


Author details

Rida Essajai Group of Semiconductors and Environmental Sensor Technologies- Energy Research Center, Faculty of Science, Mohammed V University, Rabat, Morocco

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© 2019 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/ by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


2.2.3. Synthesis of R-2A-PIP

Step 1: The preparation of R-DSC-PIP. N, N -disuccinimidyl carbonate (76.8 g, 300 mmol) and 4-dimethylaminopyridine (37.0 g, 300 mmol) were resolved in the mixed solution of dry THF (3000 mL) and DMF (1400 mL) in the three-neck bottle while R-OH-PIP (3.0 g) was resolved in dry THF (300 mL) in the flask. Secondly, the latter was slowly added into the mixed solution at 0 ◦C. The reaction was stirred at the room temperature for 8 h. The mixture was evaporated and poured into acetone to get the precipitate R-DSC-PIP. The crude grey product was collected (2.96 g, 98.7%) and the conversion ratio from hydroxyl group to carbonate group is detected with 1H-NMR, which is 97.8%, as shown in Figure S4. 1H NMR (400 MHz, Chloroform-d) δ: 5.12 (t, 2H), 4.29 (t, 2H), 2.83 (s, 4H), 2.04 (m, 10H), 1.83 (m, 2H), 1.67 (s, 3H). Step 2: The synthesis of R-2A-PIP. 2Ala-OCH2Ph (1.14 mmol) and diisopropylethylamine (DIEA, 5.5 mL) were resolved in the mixed solution of THF (150 mL) and water (14 mL) in the three-neck bottle while R-DSC-PIP (1.5 g) was resolved in dry THF (300 mL) in the flask. Secondly, the latter was slowly added into the mixed solution at 0 ◦C. The reaction was stirred at the room temperature for 8 h. The mixture was evaporated and poured into water to get the precipitate R-2A-PIP. The precipitate was washed with water for three times and the final product was dried in vacuum oven at 45 ◦C to afford a gray elastomer (1.48 g, 98.7%). The conversion ratio from carbonate group to dipeptide is detected with 1H-NMR, which is 98.3%, as shown in Figure S5. 1H NMR (400 MHz, Chloroform-d) δ: 7.34 (s, 5H), 5.12 (t, 2H), 4.61 (m, 1H), 4.21 (m, 1H), 4.04 (t, 2H), 2.04 (m, 10H), 1.83 (m, 2H), 1.67 (s, 3H).