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The present study aimed to analyze changes in health-related physical fitness among Korean elementary and middle school students before (2019) and after (2021) the COVID-19 pandemic. Data collection was completed by requesting the physical activity promotion system (PAPS) data from elementary and middle school students. This information is obtained annually by the Goyang Office of Education in Gyeonggi-do, Korea. The collected data were measured in 2019 and 2021. Data were collected from 17,000 children in the fifth and sixth grades of elementary school and about 24,000 boys and girls in the first, second, and third grades of middle school. Chi-square analyses were used to examine data from each school’s health-related physical fitness examinations. Our results indicated that physical fitness levels were significantly lower in 2021 than in 2019 across the following six areas: cardiorespiratory endurance, power, muscular strength, flexibility, obesity, and overall health-related physical fitness (p < 0.05). In addition, the ratio of students with excellent physical fitness (PAPS Grades 1 and 2) significantly decreased from 2019 to 2021, while the ratio of students with poor physical fitness (PAPS Grades 3, 4, and 5) increased (p < 0.05). In addition, there were some differences according to grade and gender. Discussions regarding the impact of decreases in physical activity on physical fitness, interpretations of physical fitness in the context of a pandemic, and practical measures that can be implemented to improve health and fitness among children and adolescents in such situations remain essential.

This study proposes a modified modulation scheme based on the phase-shifted pulse-width modulation (PS-PWM) method to improve the output performance and reduce the switching loss in cascaded H-bridge multilevel inverters. The PS-PWM method is one of the most popular modulation schemes. However, it generates significant switching loss, which can lead to the failure of power semiconductor switches. Various studies have proposed modulation schemes to reduce switching loss. The clamped discontinuous PWM (DPWM) method achieves the best switching loss reduction performance in comparison with other modulation schemes. However, the clamped DPWM method has low output characteristics, such as total harmonic distortion. The proposed modulation scheme achieves the same switching loss reduction and improved output performance by modifying the dwell time order. The proposed evenly clamped DPWM method was compared with the conventional clamped DPWM method through simulations and experiments.

This study aims to comparatively analyse the importance and performance of the health of Korean and Japanese adolescents during the prolonged coronavirus disease 2019 (COVID-19) pandemic. Data were collected from 1,341 sampled Korean and Japanese adolescents in September 2021 through online and offline surveys. The collected data were analysed with frequency analysis, reliability testing, t-test, and importance-performance analysis (IPA). The following results were obtained. First, adolescents in the two countries perceive various factors about health as important during the COVID-19 pandemic, but their performance is weak compared to their perceived importance. Second, Korean adolescents had greater perceived importance for all factors of health perception compared to their Japanese counterparts. Third, the difference in performance between Korean and Japanese adolescents was especially evident for ‘hygiene management’, and there were significant differences in performance in ‘disease management’ and ‘physical activity’. Fourth, in quadrant 4 of the IPA matrix, there were similarities and differences in a particular factor of health perception between Korean and Japanese adolescents. Based on these results, we proposed measures to emphasise the importance of health and enhance performance among Korean and Japanese adolescents.

A sinusoidal boat tail (SBT) is developed and investigated to greatly reduce drag, side force, and yawing moment under crosswind conditions. The drag and side forces of a heavy vehicle model with the SBT are reduced by 15.9 % and 22.6 %, respectively, relative to those of a reference model without the SBT at a yaw angle of 7°. Therefore, the SBT improves the aerodynamic performance and driving stability of the vehicle model. Flow characteristics around the vehicle model are measured using a particle image velocimetry technique. Mean velocity field results show that the SBT effectively suppresses the formation of longitudinal vortices by enhancing the streamwise velocity of the region behind the boat tail. In addition, the streamwise momentum deficit is reduced in the wake region owing to the development of a secondary recirculating flow region.

During the coronavirus disease 2019 (COVID-19) pandemic, social distancing guidelines changed lifestyles, including increased sedentary time, physical inactivity, and disrupted sleep patterns among children. The purpose of the present study is to analyze the health awareness (mental health, disease, physical activity, sleep, eating habit, and hygiene health management) of elementary school students during the COVID-19 pandemic, and use the importance-performance analysis (IPA) technique to identify gender differences in health perceptions. We collected data on 1006 students, which was analyzed using frequency analysis, reliability testing, independent sample t-tests, and importance-performance analysis (IPA). A median importance value of 0.163 and a median performance value of 4.048 were selected as cross points to distribute the IPA matrix into four quadrants. The highest performance was given for wearing a mask and sanitary practice; the IPA matrix indicated that the sense of belonging, happiness, trust, and movement activity were located in quadrant I. Children’s regular physical activity and level of physical activity were low, especially that of girls. Children’s sleep management was poor. Their physical activity and sleep-related factors must be improved under the facilitation of the national government, public education institutions, and families.

본 연구는 시지각 협응 활동 프로그램이 발달장애 아동의 기본운동기술 중 조작운동 기술에 미치는 영향을 규명하는 데 목적을 두고 있다. 이와 같은 연구의 목적을 달성하기 위하여 본 연구의 대상자는 A시 소재의 특수학교, 특수학급에 재학 중인 초등 아동(9세~14세)을 대상으로 부모의 동의를 얻어 11명을 선정하였으며, 프로그램 진행 전 부모와의 개별 면담을 통하여 실험 진행에 유용한 정보를 얻었다. 본 실험은 16주간, 주 2회, 1회 80분간 진행되었으며, 시지각 협응 활동 프로그램 사전과 사후 치기, 튀기기, 받기, 던지기, 굴리기 등의 6가지 항목으로 이루어진 조작운동기술에 대한 검사를 실시하였다. 자료 분석은 시지각 협응 프로그램에 따른 조작운동기술능력의 변화를 알아보기 위해 사전검사와 사후검사의 결과를 토대로 대응 표본 t-검증을 실시하였다. 본 연구 과정을 통해 얻은 결과를 분석하여 다음과 같은 결론을 얻었다. 시지각 협응 활동 프로그램은 발달장애 아동의 조작운동기술능력 중 차기를 제외한 치기, 튀기기, 받기, 던지기, 굴리기 영역을 발달시키는데 긍정적인 영향을 미치는 것으로 나타났다. 이상의 연구 결과를 종합해 보면, 시지각 협응력은 발달장애 아동의 차기를 제외한 조작운동기술능력에 영향력 있는 변인임을 알 수 있다.

This study aimed at investigating the dyeability of synthesized acid dyes on fine nylon and m-aramid and their light fastness. A sulfonic acid group was introduced into the corresponding hydrophobic dye, which has an anthraquinone structure, to allow dyeing capabilities through ionic bonding with the nylon and m-aramid. Dyeability on fine nylon and m-aramid was mainly evaluated by the UV-Vis absorbance at maximum absorption wavelength (λmax). As the dyeing temperature increased to 110°C, the exhaustion rate of synthesized acid dyes increased. The synthesized acid dyes showed higher adsorption rates when dyeing occurred at high temperature. For fine nylon, as the synthesized acid dye concentration increased, the K/S value increased to 2.5 % o.w.f. and remained at that level thereafter. The fastness of light, wash, rubbing, and perspiration of fine nylon fabric dyed at these optimum conditions had higher ratings than those of commercial acid dyes. Regarding m-aramid dyeing, the grade of light fastness was higher than that of the commercial basic dye.

As adolescents spend the majority of their time focused on exams and assignments, they do not have sufficient time to engage in physical activity, this lack of physical activity is an important public health concern. This study aimed to investigate how school-based physical activity programs affect the health-related physical fitness of adolescents in the Republic of Korea. For this study, a total of 120 high school students participated in a school-based physical activity program that included badminton and table tennis for 15 weeks each (35 min/day, three times a week), with a total of 30 weeks for one academic year. The parameters for health-related physical fitness measured muscle strength (handgrip strength), power (standing long jump), cardiorespiratory fitness (shuttle run test), flexibility (sit and reach), body mass index (BMI), and the total score. The results revealed a statistically significant improvement in muscle strength (p &lt, 0.001), power (p &lt, 0.001), cardiorespiratory fitness (p &lt, 0.001), flexibility (p = 0.005), and the overall health-related physical fitness score (p = 0.001). However, students’ BMI showed no significant difference before and after participation (p = 0.825). The results of this study indicated that school-based physical activity programs can have a positive effect on the health-related physical fitness of adolescents.

This study aimed to explore the factor structure of the Korean version of the occupational socialization of beginning physical education teachers scale, in the context of the COVID-19 pandemic, and to verify its relationship with health perception education. In October 2021, 257 Korean beginning physical education teachers were enrolled in this study. Data were analyzed using frequency analysis, exploratory factor analysis, confirmatory factor analysis, descriptive statistics, reliability analysis, and multiple regression analysis. Regarding the findings, first, the occupational socialization of beginning physical education teachers scale showed a six-factor structure: role recognition, past physical education class experience, pre-service teacher education, organizational atmosphere, fellow physical education teachers, and sports facility. Second, occupational socialization of beginning physical education teachers showed a partial positive effect on health perception education. These results suggest that the Korean Metropolitan and Provincial Offices of Education and Korean schools should develop various methods to support and ensure the occupational socialization of beginning physical education teachers. Such efforts may enable these new professionals to effectively adapt to their schools, teaching roles, and provide effective health education to students under the difficult context of the COVID-19 pandemic, wherein normal educational activities are hindered.

This paper analyzes the modulation methods based on phase-shifted PWM (PS-PWM) scheme for cascaded H-bridge multilevel inverter (CHMI). The PS-PWM scheme is one of the modulation schemes for CHMI and it generates same power loss such as switching loss and conduction loss on each cell. However, the PS-PWM scheme leads to the most switching loss than the other schemes for CHMI. Because the switching loss causes failure of power semiconductor switch, it should reduce for reliability of CHMI. In this paper, it is compared and discussed that total harmonic distortion (THD) of modulation methods based on PS-PWM scheme for reducing switching loss. To analyze characteristic each modulation method, the simulation of 3-phase 5-level CHMI is conducted.

This study aimed to develop a physical education fitness program for adolescents to counteract the declining physical activity levels caused by the COVID-19 pandemic, as well as to investigate the program&rsquo, s effect. This mixed-methods study developed and implemented a five-component &ldquo, Music Beeps&rdquo, (MB) program to promote adolescents&rsquo, physical fitness. A total of 240 students from two high schools in South Korea&mdash, divided into experimental and control groups&mdash, participated in 32 sessions over 16 weeks. The changes in students&rsquo, fitness were analyzed, and the educational effects were examined via inductive analysis of the observation logs and group and in-depth interviews. The results demonstrated that, whereas the comparison group demonstrated no statistically significant changes in power, muscular strength and endurance, or cardiopulmonary endurance, the experimental group showed changes in all these variables, along with changes in flexibility. Further, the MB program had significant educational effects. First, students reported that musical cues enhanced their fitness motivation and sense of responsibility. Second, record-keeping and active participation contributed to self-led fitness management. Third, activity in a small space with few pieces of equipment led to the positive perception that the program was efficient and enabled regular exercise regardless of climate conditions.

본 연구는 백워드 교육모형을 적용한 체육 수업이 중학교 학생들의 수업만족도에 어떠한 영향을 미치는가를 알아보는데 그 목적이 있다. 이 연구의 목적을 달성하기 위해 경기도 A중학교 258명을 연구대상으로 선정하였고, 최종 253부를 연구 자료로 사용되었다. 수집된 설문지를 기반으로 spss 21.0 통계프로그램을 통해 빈도 분석, 독립표본 t검정과 일원변량분석을 실시하였다. 그 결과 첫째, 연구대상자들의 성별에 따라 백워드 체육수업만족도에 차이를 보였다. 둘째, 학년에 따른 백워드 체육수업만족도 차이를 알아본 결과, 체육수업만족도의 하위요인인 수업운영, 교수행동, 심리적 만족도에 통계적으로 유의한 차이가 있었으며 3학년, 1학년, 2학년의 순서로 백워드 수업에 대하여 긍정적인 태도를 보였다. 셋째, 학생 성별 간 백워드 체육수업만족도 사전·사후의 차이를 알아본 결과, 수업운영, 교수행동, 심리적 만족도에서 통계적으로 유의미한 차이가 있었다. 다섯째, 학년 별 백워드 체육수업만족도의 사전·사후의 차이를 분석한 결과 수업만족도의 하위요인인 수업운영 만족도에서, 교수행동 만족도, 사회적 만족도, 심리적 만족도에서 유의미한 차이가 나타났다. 여섯째, 실험집단과 비교집단의 체육 수업만족도를 비교한결과 남학생, 여학생, 2,3학년 모두 통계적으로 유의미한 차이가 나타났다. 본 연구의 결과를 통해 성취기준 중심인 백워드 교육모형을 통해 현행 교육과정이 지향하는 바를 효율적으로 수행할 수 있고, 점차적으로 백워드 체육수업이 확대되어 효과적인 체육수업을 이루어 체육수업만족도 및 학생들의 성취도를 높일 수 있는 방안을 기대한다.

As the diameter of polyamide fibers decreased to finer denier, the dyeing fastness tends to be deteriorated due to the increase of their surface area, particularly both light fastness and wash fastness. In this study, three acid dyes were synthesized utilizing a sulfonation reaction starting from corresponding hydrophobic dye (for yellow and red dye) and dye intermediate containing a sulfonic acid group (for blue dye), those featured by high light fastness property. A Gaussian structural prediction model was used to determine the structure of the acid dyes prior to dye synthesis, and the optimal structures of three acid dyes were analyzed. Dye structures prepared were confirmed by 1H-NMR, mass spectroscopy, and elemental analysis. By using a UV-vis spectrophotometer, the absorption maxima and molar extinction coefficient were also measured for three acid dyes comparing to that of the corresponding disperse dye or blue dye intermediate. Judging from spectroscopic data, the introduction of sulfonyl groups led to increase of molar extinction coefficient and a bathochromic shift.

Learning communities in education are constructive communication networks for all teachers. Their purpose is to promote professional development, especially for new teachers. Using grounded theory, this paper explores various learning styles identified among newly admitted teachers while participating in learning communities. Nine novice male physical education teachers currently involved in learning communities were selected. Data collection included document analysis such as classroom materials and teaching journals as well as in-depth interviews. The analysis methods such as selective coding, open coding, and axial coding (Strauss and Corbin 1998) were used to analyze the collected data. Through the grounded theory research method, three different learning styles of ten beginning teachers were instantiated: (1) potential learning style, (2) passive learning style, and (3) active learning style. Although beginning teachers develop their own unique styles of professional learning, their activities in learning communities can contribute to their professional development and learning-over-the-continuum.

The improvement of the fuel efficiency of heavy vehicles has received considerable attention. Thus, various flow-control devices have been implemented to reduce aerodynamic drag exerting on heavy vehicles. In this study, we proposed noble boat tail with lower inclined air deflector (LIAD), as a passive flow-control device on attached at the rear end of heavy vehicles. The aerodynamic performance of the modified boat tail with LIAD is experimentally examined by measuring the drag force, side force exerting on a real-shaped heavy vehicle model at various yawing angles. As a result, the maximum drag reduction effect of the boat tail with LIAD (θ = 45°) is about 9.02% compared to the result without the boat tail, although the length of the bottom tail is half of that of four-way boat tail. Furthermore, particle image velocimetry velocity field measurements were conducted to investigate the modified flow structure are by the attachment of various boat tails. Consequently, the LIAD effectively suppresses the formation of large-scale recirculating zone in the wake behind the rear body of the vehicle, as an effective guide of the underbody flow.

Investigating the aerodynamic reduction of drag in heavy vehicles, such as trucks or tractor-trailers, has considerable significance given the strong influence on related industries. The underbody flow that passes through the underside of heavy vehicles induces considerable drag while interacting with rolling wheels and other structures. Nonetheless, the reduction of drag caused by underbody flow has received less attention than that attributed to upper and forebody flows. Side skirts are common underbody drag-reduction devices that consist of straight panels curtaining the underspace between the front and rear wheels to control the underbody flow in the ground clearance. In this study, we propose two different types of side skirts with flaps or additional inclined inner panels to maximize drag reduction. Effects of these devices are quantitatively evaluated by wind tunnel tests and computational fluid dynamics analysis. In wind tunnel tests with 1/8 scaled-down vehicle models, drag coefficient is reduced by more than 5% for both side skirts. Effects of various physical dimensions or angle variations on drag reduction are determined. Large-eddy simulation (LES) estimated similar drag reduction with reduced vortical activities, loss of streamwise momentum, strength of turbulent kinetic energy and global pressure difference, compared to the case without side skirts.

The ablation index (AI) is a recently developed marker for ablation lesion quality that incorporates contact force (CF), time, and power in a weighted formula. There is a paucity of information on whether AI-guided pulmonary vein isolation (PVI) could improve the outcome in patients with atrial fibrillation (AF). We evaluated the optimal AI threshold for avoiding acute pulmonary vein reconnection (PVR), and to compare the efficacy of optimal AI-targeted PVI with that of conventional CF-guided PVI. Seventy patients with AF (paroxysmal, 67%) were enrolled. In a phase 1 study, the patients underwent conventional CF-guided PVI (CON group), and the optimal AI threshold for avoiding acute PVR was identified. In phase 2, the patients underwent AI-guided PVI (OAI group). We compared the acute PVR rate between the CON group and the OAI group to demonstrate the efficacy of AI-guided PVI. In phase 1 (n = 38), acute PVR was observed in 57 of 532 (10.7%) segments. AI values of ≥ 450 at the anterior/roof segments and of ≥ 350 at the posterior/inferior/carina segments were identified as the optimal AI thresholds for avoiding acute PVR. In the phase 2 study targeting those AI values, the OAI group (n = 32) showed a significantly lower acute PVR rate than the CON group (4.2% vs. 10.7%, p

The final design of the ITER TF, CS, CC and VS AC/DC converters has been completed to implement ITER requirements following the detailed design and refinements of the preliminary design. The number of parallel thyristors and the rating of fuses are coordinated to keep those devices within the explosion limit even under most severe fault conditions. The impedance of the converter transformer has been optimized taking into account the energization inrush current, short circuit current, reactive power consumption and the available DC voltage. To ensure system integrity, AC/DC converters are mechanically divided into transformers, AC busbars, 6-pulse bridges, DC interconnecting busbars and DC reactors, and then all subsystems are decoupled by flexible links. To provide stable real time network communication down to the converters, a one GbE link is deployed between master controllers and local controllers. IEEE 1588 is implemented to the embedded controllers for precision time synchronization. This paper describes the detailed solutions implemented in the final design for the ITER AC/DC converters with R&D results of converter prototypes.

Windbreak has been used for centuries as a natural wind-fence. The functional effects of windbreaks are directly related to the flow structure. In the present study, the flow around a real fir tree placed in a wind tunnel was quantitatively visualized using PIV (particle image velocimetry) technique. The effects of tree porosity and leaves on the shelter effect were investigated as well. Tree leaves not only reduce the porosity, but also increase the wind-speed reduction and turbulence kinetic energy in the leeward region behind the tree canopy. The leaves of tree canopy induce updraft toward the top region and downdraft toward the ground in the upstream region of the tree. The momentum difference of these two flows generates peculiar upwelling flow characteristics. The large reduction in mean velocities and turbulence intensities of flow around a tree is attributed to tree leaves providing a good shelter zone in the leeward region.

A series of azo disperse dyes having dicyanovinyl groups was synthesized by the Knoevenagel condensation with malononitrile from carbonyl substituted phenylazo disperse dyes which were prepared by conventional diazo coupling reaction of aniline derivatives as diazo components. A variety of coupling components such as anilines, an indole and a pyridone were used. The azo disperse dyes were evaluated for their spectral properties and dyeing assessment on the polyester fabrics. The azo disperse dyes containing dicyanovinyl groups showed bathochromic shifts and darker colors due to increased electron withdrawing strength in their azo components and extended conjugation by dicyanovinyl groups than their parent carbonyl substituted azo dyes. The dyes containing 2-acetylamino-5-methoxy substituent in the coupling component exhibited higher wavelength of maximum absorbance (λmax) and significant negative solvatochromism than those of other dyes due to intramolecular hydrogen bonding.

The objective of this study is to elucidate the feasibility of synchrotron X-ray micro CT as a non-destructive imaging method to visualize the three-dimensional morphological structures of biological and non-biological samples. The experiments were conducted in 7B2 X-ray micro CT beamline in Pohang Accelerate Laboratory (PAL). A rotational 3-axis stage was specially designed for scanning of test samples. Preliminary tests were performed for opaque samples including a mosquito head, a plant seed and gas diffusion layer (GDL) of polymer electrolyte fuel cell to verify the feasibility of the X-ray micro CT. It visualized clearly the internal structure of all the test samples, supporting its usefulness.

In the title compound, C6H4BrN3O4, the dihedral angles between the nitro groups and the aniline ring are 2.04 (3) and 1.18 (4)°, respectively. In the crystal, N—H...O and C—H...O hydrogen bonds and weak side-on C—Br...π interactions [3.5024 (12) Å] link adjacent molecules, forming a three-dimensional network. A close O...Br contact [3.259 (2) Å] may also add additional stability.

There are many attempts to save the cost of transportation. Especially, drag reduction of heavy vehicles such as truck or tractor-trailer have enormous effect on the reduction of fuel consumption and CO2 emission, because road freight transport using heavy vehicles occupies majority in physical distribution cost.Copyright © 2015 by KSME

Some winged seeds exhibit autorotation flight during their descent to migrate far away from their parent trees by using oncoming wind. The reduced descent speed of autorotating maple seeds is attributed to the high lift force generated by a leading-edge vortex (LEV). In this study, several prominent features of the autorotation flight of maple samaras (Acer palmatum) were investigated experimentally. The autorotation flight of each maple seed was observed to be very stable during its fall. The nominal values of the dynamic motion parameters were 1.2 m/s for descent velocity, 130.9 rad/s for spinning rate, 22° for coning angle, and 1.5° for pitch angle. Velocity fields of the flow around an autorotating maple samaras model were measured by particle image velocimetry; wind speed was controlled to be similar to the descending velocity. As a result, a highly stable LEV was attached on the leeward side of the autorotating seed.

A range of monoazo blue disperse dyes has been synthesised by coupling benzenoid and heterocyclic diazo components to aniline derivatives containing ester functions. The colour properties and wet fastness of the dyes on polyester at 1/1 standard depth have been examined and rationalised in terms of dye structure. Styryl dyes have also been prepared in order to compare their wet fastness properties to those of the azo dyes.