• Korean Journal of Community Nutrition
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• v.27 no.1
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• pp.36-46
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• 2022

Objectives: The purpose of this study was to evaluate the consumption pattern of sugar-sweetened beverages (SSB) and compare body composition changes by SSB consumption based on 28 days of dietary records from a four-week time-restricted eating intervention among young adults in Korea. Methods: A total of 33 participants completed the four-week dietary intervention with 8-hour time-restricted eating (TRE). The body composition was measured by bioelectrical impedance analysis at baseline, and daily dietary records were collected for 28 days during the intervention after 4 weeks. Results: Based on 924 days of dietary records, the average eating occasion of SSB was 0.9 times per day, and the average amount of SSB was 205.8 g/times. Based on an individual's usual intake of 28 days, the average eating frequency of SSB was 16.6 times out of 28 days, and the average amount of SSB was 184.0 g/day. The average energy intake from SSB was 131.0 kcal /day (8.7% of energy), and sugar intake from SSB was 18.2 g/day (4.9% of energy). The sugar intake was 2.6% of energy from sweetened dairy products, followed by 2.0% from coffee drinks, 0.5% from soda and juice and 0.2% from others. When subjects were divided into high (14 days or more) and low (less than 14 days) SSB groups based on eating frequency, the weight change in the low SSB group was -2.0 kg over 4 weeks, which was significantly lower than -0.7 kg in the high SSB group. However, no significant difference was found in muscle mass, fat mass and body fat percent between the two groups. Conclusions: This study suggests that low consumption of sugar-sweetened beverages is more desirable in weight management despite having the dietary intervention of time-restricted eating without counting calories. Thus, further longitudinal studies on the association between SSB and obesity in Korean adults are necessary.

• Journal of the Korea institute for structural maintenance and inspection
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• v.26 no.6
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• pp.1-13
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• 2022

This study aims to investigate the feasibility of the half-cell potential (HCP) measurements on the concrete surface for evaluation of corrosion rate (or corrosion levels) of reinforcing steel in concrete. A series of experimental study is performed to measure HCP (or corrosion potential, E_corr) and corrosion current density (i_corr) of reinforcing steel in concrete cube specimens, with a side length of 200 mm. Various corrosion levels in a range of 0% to 20% of the test specimens are accelerated by impressing current to the reinforcing steel in concrete immersed in 3.0 % NaCl solution. HCP is measured in accordance with ASTM C876-15, and corrosion current density is determined by using the Stern-Geary equation and measured polarization resistance measured by electrochemical impedance spectroscopy (EIS). As a result, a numerical formula that relates HCP and i_corr in the test specimen is established by a regression analysis of the measured data in this study. It is observed that HCP is linearly correlated with log(i_corr) with a R² greater than 0.87, which is less affected by the experimental variables such as concrete mixture proportion, diameter of reinforcing steel and the amount of applied current in this study. These results exhibit that HCP measurements could be effective for evaluation of corrosion rate (or corrosion levels) of reinforcing steel in concrete in the case of exposed to a certain consistent environment.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.14 no.6
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• pp.452-460
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• 2021

As the global electric vehicle (EV) market expands, eco-friendly EV that complement performance and safety problems continue to be released and the market is growing. However, in the case of EVs, the inconvenience of charging, safety problems such as electric shock, and electromagnetic interference (EMI) problems caused by the interlocking of various electronic components are problems that must be solved in EVs. The use of wireless power transmission technology can solve the problem of safety by not dealing with high current and high voltage directly and solving the inconvenience of charging EVs. In this paper, in order to reduce EMI a wireless charging control module, which is a key electronic component of WPT of EV. EMI reduction was designed through simulation of problems such as resonance and impedance that may occur in the power supply and signal distortion between high-speed communication that may occur in the signal part. Therefore, through the EMI reduction design with power integrity and signal integrity, the WPT wireless charging control module for electric vehicles reduces 10 dBu V/m and 15 dBu V/m, respectively, in 800 MHz to 1 GHz bands and 1.5 GHz bnad.

• Journal of the Korean Electrochemical Society
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• v.24 no.4
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• pp.106-112
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• 2021

Catalyst poisoning by ionomers in membrane electrode assemblies of alkaline membrane fuel cells has been reported recently. We tried to improve the membrane electrode assembly's performance by controlling the solvent's ratio during electrode manufacturing. 4 Different mixing ratios of N-Methyl-2-pyrrolidone (NMP) and ethylene glycol (EG) gave four different cathode electrodes with platinum and Fuma-Tech ionomers. The electrode with higher EG improved polarization performance by about 36% compared to the NMP-based commercial ionomer. The dependence of the ionomer's dispersibility on the solvent seems responsible for the difference, which means that the non-uniform distribution of ionomers improves the performance of the electrode. High-frequency resistance, internal resistance corrected polarization curve, Tafel slope, mass activity, and impedance spectroscopy characterized the electrode. We can find that the existence of poor solvent improves cathode electrode performance. It seems to be the result of reduced poisoning of the catalyst according to the particle size distribution of the ionomer.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.21 no.3
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• pp.62-72
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• 2022

In this study, a miniaturized GPS band(L₁ : 1.575 GHz) antenna that can be mounted on a small drone is proposed. The miniaturization was designed by applying the perturbation method based on the λ/4 microstrip antenna and lengthening the current path at the edge of the patch. The miniaturized antenna was fabricatred such that it could be attached to the surface of styrofoam(ε_r=1.06, t=10 mm) having a size of 10 mm × 9 mm × 10 mm (0.05 λ × 0.05 λ × 0.05 λ). The thickness and length of the feeding line and the spacing between short stubs were adjusted for impedance matching. S₁₁ was found to be -18.8 dB at the center frequency of the fabricated antenna, 1.575 GHz. The radiation pattern measurement results show that the maximum gain of E_θ is 1.87 dBi in 0 directions in the xz-plane, and that E_θ is an omnidirectional characteristic with an average gain of -1.7 dBi in the yz-plane. It was found that the antenna can be used as an ultra-small microstrip antenna, which can be mounted on a small dron for GPS, and is capable of preserving a reduction ratio of 98.8% as compared to a λ/2 microstrip patch antenna.

• Journal of Nutrition and Health
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• v.56 no.4
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• pp.377-390
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• 2023

Purpose: Diabetes mellitus (DM) causes body fluid imbalance because of hyperglycemia, but there is a lack of research on the relationship between DM and body fluid imbalance in the Korean population. This study compared the differences in body fluid composition and dietary intake between individuals with type 2 DM (T2DM) and a normal control (NC) group without the disease. Methods: In this study, 36 subjects with T2DM and 21 without diabetes were divided into the T2DM and NC groups. The subjects were divided into four subgroups to assess differences in body fluid volume according to sex: men T2DM group (n = 24), men NC group (n = 9), women T2DM group (n = 12), and women NC group (n = 12). The body fluid composition was measured using bioelectrical impedance analysis, including intracellular water (ICW), extracellular water (ECW), total body water (TBW), ECW/ICW, and ECW/TBW. Nutrient intake was evaluated using their dietary records. Results: The results showed that the ECW/ICW and the ECW/TBW were significantly higher in the T2DM group compared to the NC group. Both men and women in the T2DM group showed significantly higher ECW/ICW and ECW/TBW than the respective NC group. The T2DM group had a higher carbohydrate, dietary fiber, vitamin A, vitamin C, sodium, and potassium intake per 1,000 kcal and lower total daily energy, fat, and cholesterol intake per 1,000 kcal than the NC group. Conclusion: These results suggest a positive association between T2DM and body fluid imbalance. This study can be used widely as basic data for the evaluation and diagnosis of diabetic complications in the future.

• Korean Chemical Engineering Research
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• v.61 no.2
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• pp.196-201
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• 2023

In this study, a CNT fiber flexible electrode grafted with CuO nanoparticles (CuO NPs) and polyaniline (PANI) was developed and applied to a nonenzymatic electrochemical sensor for H₂O₂ detection. CuO NPs/PANI/CNT fiber electrode was fabricated through the synthesis and deposition of PANI and CuO NPs on the CNT fiber surface using an electrochemical method. Surface morphology and elemental composition of the CuO NPs/PANI/CNT fiber electrode were characterized by scanning electron microscope with energy dispersive X-ray spectrometry. And its electrochemical characteristics were investigated by cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and chronoamperometry (CA). Compared with a bare CNT fiber as a control group, the CuO NPs/PANI/CNT fiber electrode showed a 4.78-fold increase in effective surface area and a 8.33-fold decrease in electron transfer resistance, which leads to excellent electrochemical properties such as a good electrical conductivity and an efficient electron transfer. These improved characteristics were due to the synergistic effect through the grafting of CNT fiber, PANI and CuO NPs. As a result, this electrode enhanced the H₂O₂ sensing performance.

• Exercise Science
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• v.21 no.1
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• pp.111-120
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• 2012

The purpose of the study was to assess the effects of different cardiorespiratory fitness response to exercise training on cardiovascular disease and adipocytokine release and gene expression in abdominal obesity women. forty eight middle-age women were divided to a exercise-responder (n=34) group (ERG) and a exercise-nonresponder (n=14) group (ENRG) based on cardiorespiratory fitness after exercise training (12weeks, 1200 kcal/week, moderate-vigorous intensity, walking and jogging). Cardiorespiratory fitness was measured using maximal oxygen uptake with metabolic gas analysis and body composition was determined by bioelectrical impedance. We measured lipid and glucose profiles, blood adipocytokines and adipocytokine genes expression in adipose tissue. Waist girth (p=0.040), and %body fat (p=0.031) were significantly decreased in ERG than ENRG. Triglyceride (p=0.023) and systolic blood pressure (0.046) were significantly decreased in ERG than ENRG. Blood leptin (p=0.022) was significantly decrease in ERG than ENRG but leptin gene expression was decreased both groups (p<0.001). These results show that exercise-responder group improved cardiovascular disease risk factors and adipocytokine more than exercise-nonresponder group after exercise training. Moreover, exercise-nonresponders group show that obese indices and blood leptin and leptin gene expression in adipose tissue were decreased despite the failure to improve fitness. Therefore, regular exercise training seems to give health benefits although the failure to improve fitness.

• Journal of Advanced Navigation Technology
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• v.25 no.6
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• pp.536-542
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• 2021

In this paper, we proposed a triple band printed monopole antenna with a bent branch strips for WiFi / 5G. An antenna structure in which bent strips for generating multiple resonance are attached in the form of branches was newly proposed based on a typical monopole strip vertically erected as a triple band antenna structure. The proposed antenna is designed on a FR-4 substrate with dielectric constant 4.3, thickness of 1.6 mm, and size of 28×40 mm². The measured impedance bandwidth is 430 MHz (2.22~2.65 GHz) in the 2.4 GHz WLAN, 450 MHz (3.38~3.83 GHz) in the 3.5 GHz and 2390 MHz (4.95~7.34 GHz), In particular, it has been observed that antenna has a stable omnidirectional radiation patterns as well as gain of 1.537 dBi, 1.878 dBi and 2.337 dBi in the entire frequency band of interest.

• Korean Chemical Engineering Research
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• v.62 no.1
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• pp.13-18
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• 2024

To develop flexible electrode materials for wearable devices, we investigated the electrochemical characteristics of carbon fibers tow according to pretreatment. And an electrochemical non-enzymatic sensor was fabricated using glucose as a target. The carbon fibers tow was pretreated through desizing and activation processes, and activation was performed in two ways: chemical oxidation and electrochemical oxidation. Surface morphology of carbon fibers tow samples was observed by SEM and their electrochemical characteristics and sensing performance were investigated by cyclic voltammetry, electrochemical impedance spectroscopy and chronoamperometry. Carbon fibers tow samples showed improved electrochemical properties such as reduced R_et, ΔE_p, and increased I_p through pretreatment. And similar electrochemical properties were obtained with both activation methods. We selected electrochemically activated carbon fibers tow as the final electrode material for application of electrochemical sensor. The non-enzymatic glucose sensor based on this electrode has an enhanced sensitivity of 0.744 A/mM (in a linear range of 0.09899~3.75423 mM) and 0.330 mA/mM (3.75423~50 mM), respectively. Through this study, the possibility of using carbon fibers tow was confirmed as an electrode material. It is expected to be used as basic research for development of high-performance flexible electrode materials.