• Particle and aerosol research
• /
• v.17 no.2
• /
• pp.21-27
• /
• 2021

We developed non-metallic electrodes that can replace metallic electrodes of the electrostatic precipitator(ESP) for the purpose of light weight, corrosion resistance, cost reduction. We manufactured three types of collection electrodes made of stainless steel (M), Carbon ink coating layer-Plastic sheet-Carbon ink coating layer (CPC), and Plastic sheet-Carbon ink coating layer-Plastic sheet (PCP). We studied the collection efficiency of a two-stage ESP using oil mist particles with and without collection stage by changing the flow rate, the material of collection electrode, and the applied voltage of the pre-charger module and the collection module. Here we measured concentrations of particles at diameters of 0.45 ㎛ (CMD; count median diameter) and 3.0 ㎛ (MMD : mass median diameter), as well as PM_2.5 and PM₁₀. As a result of the experiment, two-stage ESP had 22~25% higher collection efficiency in PM_2.5 than one-stage ESP at the same applied voltage. The difference in collection efficiency by varying the materials of collection electrodes was less than 5%. The weight of the non-metallic electrode was only one eighth the weight of the metal electrode. CPC electrode had a thickness of 0.27 mm, which was 1.5 times thinner than a thickness of PCP electrode, so when the flow rate increased, the CPC electrodes couldn't be kept at equal intervals due to the fluttering unlike PCP electrodes. In addition, the PCP-CPC collection module of the present experiment followed the theoretical efficiency based on Deutsch equation and Cochet's charging theory.

• Animal Bioscience
• /
• v.36 no.1
• /
• pp.75-83
• /
• 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.

• Korean Journal of Ecology and Environment
• /
• v.55 no.4
• /
• pp.330-340
• /
• 2022

We deduced the proper estimation methodology for the amount of carbon sequestration by damaged trees for Environmental Impact Assessment (EIA). The nine development projects related to renewable energy, damaged trees occur, assessment status and used method of evaluating the carbon storage of damaged trees were summarized. And after re-calculating the carbon storage of damaged trees through allometric equations, the difference between the two groups, re-calculated the damaged trees carbon storage and the damaged trees carbon storage in the report, was validated. As a result, damaged trees carbon storage in words was more than the re-calculated damaged trees carbon storage, and it was statistically significant (p<0.005). This result means that the existing method for calculating damaged tree carbon storage is overcalculated. It was judged that it was necessary to improve the calculation method. Therefore, allometric equations suitable for each dominated-tree species should be used when calculating the damaged tree carbon storage. Furthermore, we propose to establish a carbon storage calculation system based on actual data from the ecosystem so that researchers can efficiently and accurately the damaged trees carbon storage.

• Korean Journal of Culture and Social Issue
• /
• v.28 no.4
• /
• pp.627-659
• /
• 2022

This study aimed to translate and validate the Positive and Negative Ex-Relationship Thoughts (PANERT), a scale measuring the positive and negative valence of thoughts about past relationships in early adulthood. For this purpose, PANERT was translated into Korean and the study surveyed on 337 single male and female adults in their 20. Then, the gender difference between major variables was analyzed. After going through item analysis, all twelve original items were used to construct the Korean version of PANERT. The confirmatory factor analysis(CFA) supported the two factors structure of the Korean version of PANERT: positive vs, negative thought content valence. Also, the reliability coefficients of each two factors were all satisfactory. As a result of a correlation analysis, the criterion-related validity of the two sub-factors was good with other related scales(Intrusive rumination scale of K-ERRI, K-DASS-21-D, and K-PANAS-Revised) except for changes of self-perception. Finally, the research model was built to examine the mediating effect of two affect responses(positive and negative) in the relationship between two thought content valences and depression. In this process, the convergence and discriminant validity of the Korean version of PANERT were confirmed and the indirect effect was also confirmed in the structural equation model. In conclusion, the Korean version of PANERT consists of two factors and twelve items in total. Also, it is a reliable and valid tool for measuring the thought content valences in the romantic relationship breakup experience of early adults.

• Korean Journal of Social Welfare Studies
• /
• v.42 no.2
• /
• pp.5-39
• /
• 2011

The objective of this study is to survey Social Participation of the Elderly's quality of life according to their activity levels and examine the differences by their gender and age. The subjects of this study were elderly aged 60 or older who are living in the metropolitan area and those reportedly participating in various social activities at the time of the survey. A total of 586 cases were used for the analysis. Data were analyzed through multi group analysis using a structural equation model, and AMOS 7.0 was used in statistical processing. The results of this study showed that, first, the quality of life was significantly and positively affected by flow experiences in economic participation, social fellowship participation, and self development participation. Second, the results of multi group analysis on the relations between the social participation level and the quality of life according to gender demonstrated that the there were gender differences on the full path model, and that there were significant differences in relationships between the volume of social fellowship participation and the quality of life between men and women. Third, a similar finding was found for the age group that the paths between flow experiences in economic participation and the quality of life significantly differed by age groups. Based on these findings, implications for theory and practice were discussed.

• Korea Trade Review
• /
• v.42 no.5
• /
• pp.43-69
• /
• 2017

The study examined moderating role of thinking style about causality in the relationship between the perceived brand globalness(PBG) and the brand evaluation. Thinking style about causality is divided into interactionism and dispositionism. Individualism culture shows a tendency of thinking style about causality to dispositionism, and collectivist cultures shows a tendency for interactionism. We conducted a survey on Korean college students who represent collectivist cultures and foreign students from countries of individualistic culture and analyzed data through structural equation modeling. Analysis result showed that the higher the respondents perceived PBG, the higher they perceived brand quality, brand quality, and brand price. However, it showed that PBG has greater positive effects on perceived brand quality and perceived brand reputation among Korean students than students from individualistic cultures. On the other hand, the effects of PBG on perceived brand price did not show any significant difference between Korean students and students from individualist cultures. Thus, we can conclude that thinking style about causality plays a moderating role in the relationship between PBG and perceived brand quality and brand reputation, while it does not do so between PBG and perceived brand price.

• The Korean Journal of Franchise Management
• /
• v.9 no.3
• /
• pp.31-43
• /
• 2018

Purpose - This study examines the role of foodservice franchisee's perceived justice(distributive, procedural, and interactional) in developing long-term orientation to franchisor and investigate the mediating role of cohesiveness and relationship satisfaction in the relationship between franchisee's perceived justice and long-term orientation to franchisor. Research design, data, and methodology - We collected data from managers and owners in foodservice franchisees located in Seoul, Korea. Among a total of 500 questionnaires, 500 questionnaires were returned. After excluding 36 invalid respondent questionnaires, 496 valid questionnaires(response rate of 99.2%) were analyzed using frequency, confirmatory factor analysis, correlations analysis, and structural equation modeling with SPSS 21 and SmartPLS 3.0. Result - The findings of this study are as follows: First, distributive justice and interactional justice had positive effects on cohesiveness, but procedural justice did not. Second, distributive justice and interactional justice had positive effects on relationship satisfaction, but procedural justice did not. Third, cohesiveness and relationship satisfaction had positive effects on franchisee's long-term orientation to franchisor. Conclusions - The implications of this study are as follows. First, this study found that procedural justice can create a high cohesiveness and identification of franchisee and also maintain a cooperative relationship with the franchisor. Second, this findings suggest that the perceived distributional and interactional justice can improve the satisfaction with the franchisor and thus positively influence the intention to maintain the relationship and the intention to recontract. Third, the results of this study indicate that the cohesiveness of franchisees can play a pivotal role to improve their satisfaction with the franchisor and pursue mutual development by continuously maintaining stable business relationship with franchisor. The findings of this study are subject to at least three limitations. First, the research subject is limited to the food service franchise shops in Seoul area, so the sample was not nationally representative of the franchise stores. Second, the perceived fairness is measured only from the point of view of the franchisee, and this study has a limitation to examine the difference between the perceived franchisee's and franchisor's justice. Third, Future research needs to identify more closely the relationships between perceived fairness and long-term orientation by gathering specific quantitative data such as the renewal rate and the business performance.

• Korean Journal of Social Welfare Studies
• /
• v.44 no.2
• /
• pp.327-358
• /
• 2013

This study aimed to analyze the trajectories of cognitive function and functional disability, and to identify the impacts of socio-demographic factors on the two variables. Based on the assumption that there are differences according to the progress of cognitive impairment, it focused on examining the differences in trajectories of cognitive function and functional disability between two groups: dementia conversion group and dementia non-conversion group among cognitively normal older adults. This study was conducted based on the data from a 3-wave panel study of a sample of 966 Yeoncheon elderly cohort aged 65 and over between 1997 and 2003. Latent growth curve model and multi-group structural equation modeling were used to examine the hypothesis. Results revealed that dementia conversion group exhibited faster rate of cognitive decline as well as lower initial cognitive level. Difference between two groups was not significant in the initial level of functional disability, yet dementia conversion group showed greater degree of deterioration in the functional disability over time than dementia non-conversion group did. In terms of the influence of socio-demographic factors on cognitive function and functional disability, the cognitive decline was more drastic in the female group, whereas functional decline was more apparent for the male group. The level of education in early life had a strong impact on the cognitive function in later life. Based on these findings, practical implication for high risk groups in cognitive function and functional disability were discussed.

• Applied Chemistry for Engineering
• /
• v.35 no.1
• /
• pp.16-22
• /
• 2024

Polymer electrolyte membrane fuel cells have the advantage of low operating temperatures and fast startup and response characteristics compared to others. Simulation studies are actively researched because their cost and time benefits. In this study, the resistance of water residual in the gas diffusion layer (GDL) of the unit cell was added to the existing equation to compare the actual data with the model data. The experiments were conducted with a 25 cm² unit cell, and the samples were separated into stopping times of 0, 10, and 60 minutes following primary impedance measurement, activation, and polarization curve data acquisition. This gives 0, 10, and 60 minutes for the residual water in the GDL to evaporate. Without the rest period, the magnitude of the performance improvement was not significantly different at the same potential and flow rate, but the rest period did improve the performance of the membrane electrode assembly when measuring impedance. By changing the magnitude of the resistance reduction to an overvoltage, the voltage difference between the fuel cell model with and without residual water was compared, and the error rate in the high current density region, which is dominated by concentration losses, was reduced.

• The Journal of the Acoustical Society of Korea
• /
• v.28 no.4
• /
• pp.318-327
• /
• 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.