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Abstract Background Physical fitness is considered an important indicator of the health of the general public. In particular, the physical fitness of the older adults is an important requirement for determining the possibility of independent living. Therefore, the purpose of this study was to examine the association between chronological age and physical fitness variables in the National Fitness Award Cohort study data and to develop multiple linear regression analyses to predict fitness age using dependent variables. Methods Data from 501,774 (359,303 adults, 142,471 older adults) individuals who participated in the Korea National Fitness Award Cohort Study from 2017 to 2021 were used. The physical fitness tests consisted of 5 candidate markers for adults and 6 candidate markers for the older adults to measure muscle strength, muscle endurance, cardiopulmonary endurance, flexibility, balance, and agility. Pearson’s correlation and stepwise regression analyses were used to analyze the data. Results We obtained a predicted individual fitness age values from physical fitness indicators for adults and older adults individuals, and the mean explanatory power of the fitness age for adults was [100.882 – (0.029 × VO2max) – (1.171 × Relative Grip Strength) – (0.032 × Sit-up) + (0.032 × Sit and reach) + (0.769 × Sex male = 1; female = 2)] was 93.6% (adjusted R2); additionally, the fitness age for older adults individuals was [79.807 – (0.017 × 2-min step test) – (0.203 × Grip Strength) – (0.031 × 30-s chair stand) – (0.052 × Sit and reach) + (0.985 × TUG) – (3.468 × Sex male = 1; female = 2) was 24.3% (adjusted R2). Conclusions We suggest the use of fitness age as a valid indicator of fitness in adults and older adults as well as a useful motivational tool for undertaking exercise prescription programs along with exercise recommendations at the national level.

PURPOSE The relationship between depression and physical activity levels in adults in Korea was determined using data from the National Health and Nutrition Survey (K-NAESE). METHODS Data collected from K-NAESE between 2014 and 2020, comprising 29,716 (male: 13,416, female: 16,300) participants, were analyzed using a complex sample statistical analysis by applying differential weight to the variables to analyze the relationship between depression and physical activity levels in an estimated South Korean population (50,881,242). Demographic factors were used as control variables while constructing an independent variable-by-variable fit model for the zero-inflated Poison Regression analysis of PHQ-9 depression scores, and a meaningfully interpretable fit model was used in the final model. RESULTS A significant relationship was observed between the total PHQ-9 score and commute physical activity (OR=1.042; SE, 0.006; p

OBJECTIVES The purpose of this study is to compare and analyze the group differences in musculoskeletal injury and rehabilitation and physical exercise according to the level of handicap for female elite amateur golfers. METHODS We sampled 191 female golfers (mean age 17.61, SD=1.50) and examined individual and golf-specific characteristics, and medical history. Subgroups with different handicaps (10) were compared using one-way analysis of variance and frequency analysis tests. RESULTS In the sub-group divided by handicap level, there were significant differences between the groups in terms of career, scoring average, and greens in regulation, and in the injury-related questions, they responded in the order of muscle pain, blisters, and ligament rupture. The response rate for the body parts of injury was high in the order of wrist, lower back, and shoulder, and statistically significant differences between the groups in terms of fracture and shoulder, hand, and lower back. In the questionnaire on warm-up, stretching and practice swing showed significant differences between groups, and cool-down exercise showed significant differences only in practice swing. Finally, Fitness training time showed a significant difference between groups. CONCLUSIONS In conclusion, the purpose of this study is to provide data for understanding golf injury and prevention of injury, and the results of this study can help inform further research on preventing injuries in golfers' most frequent injury areas and further establishing injury prevention management strategies.

OBJECTIVES The purpose of this study is to analyze the trend of yearly changes in adolescent body composition and health-related physical fitness variables using National Fitness Award. METHODS We sampled 209.924 adolescents (age: 13.99 ± 0.85) and investigated their body composition, muscle strength, and cardiopulmonary function. Subgroups by year (2018, 2019, 2020, 2021, 2022) were compared using one-way analysis of variance and frequency analysis tests. RESULTS In the subgroup classified by year, there were significant differences between groups in height, BMI, and gender, and there were significant differences between groups in relative grip strength, 20m PACER, and maximal oxygen consumption. CONCLUSIONS In conclusion, this study presents changes in body composition, muscle strength, and cardiopulmonary function by year as basic data to help understand adolescents' health conditions, and it is expected to provide data that can have a positive impact for future use as clinical and public health information.

Abstract Metasurfaces have been continuously garnering attention in both scientific and industrial fields, owing to their unprecedented wavefront manipulation capabilities using arranged subwavelength artificial structures. To date, research has mainly focused on the full control of electromagnetic characteristics, including polarization, phase, amplitude, and even frequencies. Consequently, versatile possibilities of electromagnetic wave control have been achieved, yielding practical optical components such as metalenses, beam-steerers, metaholograms, and sensors. Current research is now focused on integrating the aforementioned metasurfaces with other standard optical components (e.g., light-emitting diodes, charged-coupled devices, micro-electro-mechanical systems, liquid crystals, heaters, refractive optical elements, planar waveguides, optical fibers, etc.) for commercialization with miniaturization trends of optical devices. Herein, this review describes and classifies metasurface-integrated optical components, and subsequently discusses their promising applications with metasurface-integrated optical platforms including those of augmented/virtual reality, light detection and ranging, and sensors. In conclusion, this review presents several challenges and prospects that are prevalent in the field in order to accelerate the commercialization of metasurfaces-integrated optical platforms.

Background : Bone mineral density (BMD) has been associated with fitness, nutrition, lifestyle, and genetic factors such as sex and race. The aim of this study was to determine whether athletic performance in middle-to-old-aged men affected the development of osteopenia. Methods : This cross-sectional study pooled data collected from 3,560 men in their 40-70’s. BMD was measured by dual-energy X-ray absorptiometry at the lumbar spine 1-4 and the femoral neck. The fitness tests included strength (grip strength), flexibility (trunk forward flexion), and cardiopulmonary fitness (maximum oxygen consumption, VO₂max). Results : The participants in the normal and osteopenia groups were aged 49.9±5.0 (mean±standard deviation) and 50.4±5.1 years, respectively. Those in the highest quartile (Q4) of VO₂max had a significantly increased risk of having osteopenia (adjusted odds ratio 1.687; 95% confidence interval [CI] 1.193-2.387; p=0.003). Participants in the highest quartile (Q4) of grip strength had a significantly higher adjusted odds ratio (1.445) of having osteopenia (95% CI, 1.099-1.857; p=0.009). Finally, flexibility was 1.454 times higher for the lowest group (Q4) than for the highest group (Q1) (95% CI, 1.194-1.887; p=0.003). Conclusion : Higher levels of cardiopulmonary fitness and flexibility in middle-aged men may decrease the prevalence of osteopenia and prevent loss of BMD.

In recent years, research on the application of microdroplets in the fields of biotechnology and chemistry has made remarkable progress, but the technology for the stable generation of single-micrometer-scale microdroplets has not yet been established. In this paper, we developed an efficient and stable single-micrometer-scale droplet generation device based on the fragmentation of droplet tails, called “tail thread mode”, that appears under moderate flow conditions. This method can efficiently encapsulate microbeads that mimic cells and chemical products in passively generated single-micrometer-scale microdroplets. The device has a simple 2D structure; a T-junction is used for droplet generation; and in the downstream, multi-branch channels are designed for droplet deformation into the tail. Several 1–2 µm droplets were successfully produced by the tail’s fragmentation; this continuous splitting was induced by the branch channels. We examined a wide range of experimental conditions and found the optimal flow rate condition can be reduced to one-tenth compared to the conventional tip-streaming method. A mold was fabricated by simple soft lithography, and a polydimethylsiloxane (PDMS) device was fabricated using the mold. Based on the 15 patterns of experimental conditions and the results, the key factors for the generation of microdroplets in this device were examined. In the most efficient condition, 61.1% of the total droplets generated were smaller than 2 μm.

Background: Fibroblast growth factor-2 (FGF-2) protein level has been shown to be elevated in aged mice muscle compared to adult mice. It activates the satellite cell quiescence, which leads to satellite cell depletion and may accelerate aging process. The purpose of this study was to see the effect of resistance exercise on skeletal muscle FGF-2 protein level in aged mice. Methods: This study included eight young adult control C57BL/6 male mice (age 12 weeks, YCON group) and 14 aged C57BL/6 male mice (age 19 months), randomly divided into two groups (old control, OCON, n = 7; old resistance exercise, ORT, n = 7). Resistance ladder climbing exercise was conducted 3 d/wk for 12 weeks. Soleus and tibialis anterior muscles were collected for body composition, relative grip strength, and muscle wet weight and for enzyme-linked immunosorbent assay protein analysis. Results: Relative soleus muscle wet weight and hindlimb lean mass showed a significant increase in ORT group compared to OCON group (p = 0.013 and p = 0.015, respectively). In relative grip strength, both OCON and ORT showed a significant decrease compared to YCON (p

Recently, chemical operations with microfluidic devices, especially droplet-based operations, have attracted considerable attention because they can provide an isolated small-volume reaction field. However, analysis of these operations has been limited mostly to aqueous-phase reactions in water droplets due to device material restrictions. In this study, we have successfully demonstrated droplet formation of five common organic solvents frequently used in chemical synthesis by using a simple silicon/glass-based microfluidic device. When an immiscible liquid with surfactant was used as the continuous phase, the organic solvent formed droplets similar to water-in-oil droplets in the device. In contrast to conventional microfluidic devices composed of resins, which are susceptible to swelling in organic solvents, the developed microfluidic device did not undergo swelling owing to the high chemical resistance of the constituent materials. Therefore, the device has potential applications for various chemical reactions involving organic solvents. Furthermore, this droplet generation device enabled control of droplet size by adjusting the liquid flow rate. The droplet generation method proposed in this work will contribute to the study of organic reactions in microdroplets and will be useful for evaluating scaling effects in various chemical reactions.

This paper presents methods for the formation of hollow microcapsules and microlenses using multiphase microdroplets. Microdroplets, which consist of a gas core and an organic phase shell, were generated at a single junction on a silicon device without surface treatment of the fluidic channels. Droplet, core and shell dimensions were controlled by varying the flow rates of each phase. When the organic solvent was released from the organic phase shell, the environmental conditions changed the shape of the solidified polymer shell to either a hollow capsule or a microlens. A uniform solvent release process produced polymeric capsules with nanoliter gas core volumes and a membrane thickness of approximately 3 μm. Alternatively physical rearrangement of the core and shell allowed for the formation of polymeric microlenses. On-demand formation of the polymer lenses in wells and through-holes polydimethylsiloxane (PDMS) structures was achieved. Optical properties of the lenses were controlled by changing the dimension of these structures.

This paper presents a method for utilizing three-dimensional microfluidic channels fully to realize multiple functions in a single device. The final device structure was achieved by combining three independent modules that consisted of horizontal and vertical channels. The device allowed for the one-step generation of water-in-oil-in-water droplets without the need for partial treatment of the polydimethylsiloxane channel surface using separate modules for generating water-in-oil droplets on the horizontal plane and oil-in-water droplets on the vertical plane. The second vertically structured module provided an efficient flow for the generation of highly wettable liquid droplets, and tuning of the first horizontally structured module enabled different modes of inner-core encapsulation within the oil shell. The successful integration of the vertical and horizontal channels for core-shell droplet generation and the chemical synthesis of a metal complex within the droplets were evaluated. The proposed approach of integrating independent modules will expand and enhance the functions of microfluidic platforms.

This paper presents a microfluidic system for the active and precise control of microdroplet division in a micro device. Using two horizontal pneumatic valves formed at downstream of bifurcating microchannel, flow resistances of downstream channels were variably controlled. With the resistance control, volumetric ratio of downstream flows was changed and water-in-oil microdroplets were divided into two daughter droplets of different volume corresponding to the ratio. The microfluidic channels and pneumatic valves were fabricated by single-step soft lithography process of PDMS (polydimethylsiloxane) using SU-8 mold. A wide range control of the daughter droplets’ volume ratio was achieved by the simple channel structure. Volumetric ratio between large and small daughter droplets are ranged from 1 to 70, and the smallest droplet volume of 14 pL was obtained. The proposed microfluidic device is applicable for precise and high throughput droplet based digital synthesis.

We present an active droplet merging device, which can merge various sizes of micro droplets in different numbers by using pneumatically controlled horizontal PDMS microvalves. The merging part consists of a main and side channels separated by a pillar array. The pillar array structure is contained within a microfuidic channel. The function of the pillar array provides a bypass path to the continuous flow (oil) inside the merging chamber. Droplets are successfully generated within the channel and achieve merging by controlling the selective different numbers and diameters of droplets through varying the flow resistance of main and side channel. In the merging chamber, a droplet will enter and slow down its movement. It will wait and then merge with the sequential droplets. These experiments demonstrate that such a merging device can controllably select and adjust the distance between the different adjacent micro droplets without any generation of sister droplets in the side channel. The device has no desynchronization problems. Thus, it can be applied for efficiently mixing the droplets in various diameters and numbers without changing the structure of the merging chamber. Hence, this device can be a more effective choice when applying microfluidics to chemical and biological applications.

Purpose: The paper validates a model which approximates a relationship between perceived uncertainty of consumers and two antecedents & three mitigators which explain the value of Food Traceability System (FTS). Methodology/Approach: The proposed model was drawn from Pavlou et al. (2007) study which applied the principal-agent perspectives, and this study contributes to the current literature by improving understanding of the structure of perceived uncertainty of a food product with credence good with this model. Findings: The study assesses the value and effects of FTS in reducing perceived uncertainty of beef from various origins and suggests important implications for stakeholders in beef sector regarding feasibility and marketability of FTS. Research Limitation/Implication: Findings evidently reflect the current market circumstance regarding consumers’ concerns and Perceived Uncertainty towards import food products for their credence nature. Different aspects of FTS were found to have the mediating role in reducing Perceived Uncertainty in China and South Korea. Originality/Value of paper: The study assesses the value and effects of FTS in reducing perceived uncertainty of beef from various origins and suggests important implications for stakeholders in beef sector regarding feasibility and marketability of FTS.

A fully passive microdroplet sorting method is presented in this paper. On the rails with dot patterns, the droplets were sorted in different ways depending on their size. However, the effect of droplet properties on the threshold size of the sorting was eliminated. The droplet positions on two railways and the Laplace pressure of the droplets on the dot patterns allowed selective droplet transfer according to size. Different gaps between the rails altered the threshold size of the transfer. However, the threshold size was independent of the droplet’s surface tension and viscosity because the droplet transfer utilized only the droplet position and Laplace pressure without lateral flow to sort targets. This feature has a high potential for bio/chemical applications requiring categorization of droplet targets consisting of various mixtures as pre- or post-elements.

This paper presents a simple method of droplet formation using liquids that easily wet polydimethylsiloxane (PDMS) surfaces without any surface treatment. Using only structural features and uniform flow focusing, Oil-in-Water (O/W) and Water-in-Oil-in-Water (W/O/W) droplets were formed in the full PDMS structure. Extrusion channel and three-dimensional flow focusing resulted in effective fluidic conditions for droplet formation and the droplet size could be precisely controlled by controlling the flow rate of each phase. The proposed structure can be utilized as an important element for droplet based research, as well as a droplet generator.

Sampling-based PLLs have become a new research trend due to the possibility of removing the frequency divider (FDIV) from the feedback path, where the FDIV increases the contribution of in-band noise by the factor of dividing ratio square (N2). Between two possible sampling methods, sub-sampling and reference-sampling, the latter provides a relatively wide locking range, as the slower input reference signal is sampled with the faster VCO output signal. However, removal of FDIV makes the PLL not feasible to implement fractional-N operation based on varying divider ratios through random sequence generators, such as a Delta-Sigma-Modulator (DSM). To address the above design challenges, we propose a reference-sampling-based calibration-free fractional-N PLL (RSFPLL) with a phase-interpolator-linked sampling clock generator (PSCG). The proposed RSFPLL achieves fractional-N operations through phase-interpolator (PI)-based multi-phase generation instead of a typical frequency divider or digital-to-time converter (DTC). In addition, to alleviate the power burden arising from VCO-rated sampling, a flexible mask window generation method has been used that only passes a few sampling clocks near the point of interest. The prototype PLL system is designed with a 65 nm CMOS process with a chip size of 0.42 mm2. It achieves 322 fs rms jitter, −240.7 dB figure-of-merit (FoM), and −44.06 dBc fractional spurs with 8.17 mW power consumption.

Ultra-wideband (UWB) wireless communication is prospering as a powerful partner of the Internet-of-things (IoT). Due to the ongoing development of UWB wireless communications, the demand for high-speed and medium resolution analog-to-digital converters (ADCs) continues to grow. The successive approximation register (SAR) ADCs are the most powerful candidate to meet these demands, attracting both industries and academia. In particular, recent time-interleaved SAR ADCs show that multi-giga sample per second (GS/s) can be achieved by overcoming the challenges of high-speed implementation of existing SAR ADCs. However, there are still critical issues that need to be addressed before the time-interleaved SAR ADCs can be applied in real commercial applications. The most well-known problem is that the time-interleaved SAR ADC architecture requires multiple sub-ADCs, and the mismatches between these sub-ADCs can significantly degrade overall ADC performance. And one of the most difficult mismatches to solve is the sampling timing skew. Recently, research to solve this timing-skew problem has been intensively studied. In this paper, we focus on the cutting-edge timing-skew calibration technique using a window detector. Based on the pros and cons analysis of the existing techniques, we come up with an idea that increases the benefits of the window detector-based timing-skew calibration techniques and minimizes the power and area overheads. Finally, through the continuous development of this idea, we propose a timing-skew calibration technique using a comparator offset-based window detector. To demonstrate the effectiveness of the proposed technique, intensive works were performed, including the design of a 7-bit, 2.5 GS/s 5-channel time-interleaved SAR ADC and various simulations, and the results prove excellent efficacy of signal-to-noise and distortion ratio (SNDR) and spurious-free dynamic range (SFDR) of 40.79 dB and 48.97 dB at Nyquist frequency, respectively, while the proposed window detector occupies only 6.5% of the total active area, and consumes 11% of the total power.

PURPOSE: The purpose of this study is to develop and verify the validity and reliability of the Korean version of the Korea Institute of Sports Science (KISS) golf conditioning questionnaire survey. METHODS: A total of 320 professional and elite-amateur female golfers were recruited and parallel analysis and exploratory factor analysis were conducted to evaluate the suitability of the intended five-factor model (physical fitness, injury, nutrition, mental, and performance strategy). Confirmatory factor analysis was also used to determine the questions by evaluating goodness-of-fit indexes. RESULTS: 5-factor model was supported by showing Bayesian information criterion -386.75, Tucker-Lewis index 0.947, root square error of approximation 0.049 and standardized root mean square residual 0.03. The final model of the Korean version KISS golf conditioning questionnaire survey showed a comparative fit index of 0.928, Tucker-Lowis index of 0.908, root mean square residual of 0.066, and standardized root mean square residual of 0.077, confirming the suitability of the model. CONCLUSIONS: This study demonstrated the feasibility and reliability of the Korean version KISS conditioning questionnaire survey for Korean elite female golfers. The objective evaluation prior to plan and execute conditioning using this evaluation tool will allows elite female golfers to obtain essential information to optimize the concurrent conditioning. [ABSTRACT FROM AUTHOR]