• Animal Bioscience
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• 제36권1호
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• pp.75-83
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• 2023

Objective: The objective of this study was to describe a methodological procedure to quantify the heat production (HP) partitioning in basal metabolism or fasting heat production (FHP), heat production due to physical activity (HPA), and the thermic effect of feeding (TEF) in roosters. Methods: Eighteen 54-wk-old Hy Line Brown roosters (2.916±0.15 kg) were allocated in an open-circuit chamber of respirometry for O₂ consumption (VO₂), CO₂ production (VCO₂), and physical activity (PA) measurements, under environmental comfort conditions, following the protocol: adaptation (3 d), ad libitum feeding (1 d), and fasting conditions (1 d). The Brouwer equation was used to calculate the HP from VO₂ and VCO₂. The plateau-FHP (parameter L) was estimated through the broken line model: HP = U×(R-t)×I+L; I = 1 if t<R or I = 0 if t>R; Where the broken-point (R) was assigned as the time (t) that defined the difference between a short and long fasting period, I is conditional, and U is the decreasing rate after the feed was withdrawn. The HP components description was characterized by three events: ad libitum feeding and short and long fasting periods. Linear regression was adjusted between physical activity (PA) and HP to determine the HPA and to estimate the standardized FHP (st-FHP) as the intercept of PA = 0. Results: The time when plateau-FHP was reached at 11.7 h after withdrawal feed, with a mean value of 386 kJ/kg^0.75/d, differing in 32 kJ from st-FHP (354 kJ/kg^0.75/d). The slope of HP per unit of PA was 4.52 kJ/mV. The total HP in roosters partitioned into the st-FHP, termal effect of feeding (TEF), and HPA was 56.6%, 25.7%, and 17.7%, respectively. Conclusion: The FHP represents the largest fraction of energy expenditure in roosters, followed by the TEF. Furthermore, the PA increased the variation of HP measurements.

• Journal of the Korean Society of Environmental Restoration Technology
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• 제25권6호
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• pp.35-50
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• 2022

As the water shortage has become a noticeable issue due to climate change, forests play an importance role as the provider of water supply service. There is, however, little information about the relationships between the factors used in the estimation of water supply service and coarse pore fraction of forest soil which determines the potential of water supply. To find out whether there would be an amelioration in the scoring system of water supply service estimation, we examined all factors except meteorological one and additionally, analyzed 4 extra factors that might be related with coarse pore fraction of soil. A total of 2,214 soil samples were collected throughout South Korea to measure coarse pore fractions from 2015 to 2020. First, the result of average coarse pore fraction of all samples showed 32.98±6.59% which was consistent with previous studies. And the results of non-parametric analysis of variance indicated that only two of eleven factors that was used in the scoring system matched the results of coarse pore fraction of forest soils. Tree canopy coverage showed no difference among categories, and slope also showed no significance at level of 0.05 in the linear regression analysis. Additionally, the applicability of 4 extra factors were confirmed, as the result of coarse pore fractions of soil samples were different for various categories of each factor. Therefore, the scoring system of water supply service of forest should be revised to improve accuracy.

• Journal of the Korean Electrochemical Society
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• 제24권4호
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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.

• 한국체육학회지인문사회과학편
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• 제55권2호
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• pp.643-655
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• 2016

The purpose of this study was to investigate biomechanical differences between young and old adults during downhill walking on a treadmill in order to understand the mechanisms of elderly falls. Eighteen healthy young females(YG: yrs: 21.17±1.5) and eighteen healthy old females(OG: yrs: 66.67±1.33) participated in this study. They were asked to walk at their preferred speed on a treadmill at level, 7.5° and 15° decline. OG walked more wobbly in the medial and lateral directions than YG(p<.05). As slope got steeper, OG had smaller ROM(range of motion) of ankle and knee joints compared with YG. However, there was no difference in ROM of the hip between OG and YG, but maximum extension angle of OG was smaller compared with YG(p<.05). Smaller extensor moment was generated on OG during downhill walking(p<.05). It was hypothesized that more risk factors would be found on older people compared to young people during downhill. However, older people actually walks with a safer strategy compared to young people during downhill. Finally, current findings about biomechanical characteristics of elderly walking would provide useful fundamental information for a follow-up study regarding the prevention of elderly fall during their daily life.

• Journal of the Korean Society of Marine Environment & Safety
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• 제29권4호
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• pp.407-416
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• 2023

Demand for leisure facilities such as mooring facilities for berthing leisure vessels and floating pensions based on floating bodies is increasing owing to the rapid growth of the population and related industries for marine leisure activities. Owing to its relatively light weight as a fluid, inclination is easily generated by waves and surcharges flowing to the coast, resulting in frequent safety accidents because of the low stability. As a solution to this problem, a motion reduction device for floating bodies is proposed in this study. The device (motion reduction device based on the air pressure dif erence) was attached to a floating body and the effect was analyzed by comparing the results with those of a floating body without motion reduction. The effect analysis was further analyzed using a computer analysis test, and the method for increasing the stability of the floating body was studied, and its the effect was verified. Based on the analysis of the test results, the stability of the floating body increased with a motion damping device is higher than that of the floating body without a motion reducing device as the wave momentum reduces, owing to the air pressure difference. Therefore it was concluded that the use of such a device for reducing motion a floating body is useful not only for non-powered ships but also for powered and semi-submersible ships, and further research should be conducted by applying it to various fields.

• Korean Journal of Culture and Social Issue
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• 제21권1호
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• pp.45-66
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• 2015

This study explored the moderating effects of social supports (family support, home friends support, foreign friends support) and cultural identity (home identity, foreign identity) on the relationships of reverse culture shock and subjective well-being. Participants were 157 returnees who left home-country prior to the age of 19 and resided in the foreign-country for more than three years. The results of hierarchical regression analyses on two-way interaction effect between reverse culture shock and each hypothesized moderator (e.g., family support, home friends support, foreign friends support, home identity, foreign identity) indicated that reverse cultural shock and subjective well-being was negatively related and their relationship was moderated only by family support. Specifically, the relationship between reverse culture shock and subjective well-being was weaker when the level of family support was higher. Subsequently, three-way interaction among reverse culture shock, one of the social support factors, and one of the cultural identity factors was investigated using hierarchical regression analyses. The results showed that the three-way interaction among reverse culture shock, family support, and home identity was significant. The slope difference tests yielded that the relationship between reverse culture shock and subjective well-being was stronger when both levels of family support and home identity were lower compared to when either level of family support or home identity was higher. These results imply that environmental factors such as family support and intrapsychic factor such as home identity might function as a buffer against the negative consequences of reverse culture shock experience.

• Phonetics and Speech Sciences
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• 제15권3호
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• pp.17-25
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• 2023

This study examines the fundamental frequency(f0) distribution of 2,740 Korean speakers in a dialogue speech corpus. Praat and R were used for the collection and analysis of acoustical f0 data after removing extreme values considering the interquartile f0 range of the intonational phrases produced by each individual speaker. Results showed that the average f0 value of all speakers was 185 Hz and the median value was 187 Hz. The f0 data showed a positively skewed distribution of 0.11, and the kurtosis was -0.09, which is close to the normal distribution. The pitch values of daily conversations varied in the range of 238 Hz. Further examination of the male and female groups showed distinct median f0 values: 114 Hz for males and 199 Hz for females. A t-test between the two groups yielded a significant difference. The skewness representing the distribution shape was 1.24 for the male group and 0.58 for the female group. The kurtosis was 5.21 and 3.88 for the male and female groups, and the male group values appeared leptokurtic. A regression analysis between the median f0 and age yielded a slope of 0.15 for the male group and -0.586 for the female group, which indicated a divergent relationship. In conclusion, a normative f0 distribution of different Korean age and sex groups can be examined in the conversational speech corpus recorded by a massive number of participants. However, more rigorous data might be required to define a relation between age and f0 values.

• Journal of the Korean Geotechnical Society
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• 제39권12호
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• pp.47-60
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• 2023

At present, in South Korea, there is a growing concern regarding solar power facilities installed on slopes because they are prone to damage caused by natural disasters, such as heavy rainfall and typhoons. Each year, these solar power facilities experience soil erosion due to heavy rainfall and foundation damage or detachment caused by strong wind loads. Despite these challenges, the interaction between the ground and structures is not adequately considered. Current analyses primarily focus on the structural stability under external loads; the overall facility site's stability-excluding the solar structures-in relation to its surrounding slopes is neglected. Therefore, in this study, we use finite-difference method analysis to simulate the behavior of the foundation and piles to assess changes in lateral displacement and bending stress in piles, as well as the safety factor of sloped terrains, in response to various influencing factors, such as pile diameter, spacing between piles, pile-embedding depth, wind loads, and dry and wet conditions. The analysis results indicate that pile spacing and wind loads significantly influence lateral displacement and bending stress in piles, whereas pile-embedding depth strongly influences the safety factor of sloped terrains. Moreover, we found that under certain conditions, the design criteria in domestic standards may not be met.

• The Journal of the Acoustical Society of Korea
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• 제28권4호
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• pp.318-327
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• 2009

In this paper, we propose a 3-D geometric localization method for near-field broadband source in shallow water environments. According to the waveguide invariant theory, slope of the interference pattern which is seen in a sensor spectrogram directly proportional to a range of the source. The relative ratio of the range between source and sensors was estimated by matching of two interference patterns in spectrogram. Then this ratio is applied to the Apollonius's circle which shows the locus of a source whose range ratio from two sensors is constant. Two Apollonius's circles from three sensors make the intersection point that means the horizontal range and the azimuth angle of the source. And this intersection point is constant with source depth. Therefore the source depth can be estimated using 3-D hyperboloid equation whose range difference from two sensors is constant. To evaluate a performance of the proposed localization algorithm, simulation is performed using acoustic propagation program and analysis of localization error is demonstrated. From simulation results, error estimate for range and depth is described within 50 m and 15 m respectively.

• Journal of Korean Tunnelling and Underground Space Association
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• 제25권6호
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• pp.403-421
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• 2023

As the number of underground structures has increased in recent decades, it has become crucial to predict geological hazards ahead of a tunnel face during tunnel construction. Consequently, this study developed a finite element (FE) numerical model to simulate electrical resistivity surveys in tunnel boring machine (TBM) operations for predicting mixed ground conditions in front of tunnel faces. The accuracy of the developed model was verified by comparing the numerical results not only with an analytical solution but also with experimental results. Using the developed model, a series of parametric studies were carried out to estimate the effect of geological conditions and sensor geometric configurations on electrical resistivity measurements. The results of these studies showed that both the interface slope and the difference in electrical resistivity between two different ground formations affect the patterns and variations in electrical resistivity observed during TBM excavation. Furthermore, it was revealed that selecting appropriate sensor spacing and optimizing the location of the electrode array were essential for enhancing the efficiency and accuracy of predictions related to mixed ground conditions. In conclusion, the developed model can serve as a powerful and reliable tool for predicting mixed ground conditions during TBM tunneling.