• Applied Chemistry for Engineering
• /
• v.25 no.1
• /
• pp.78-83
• /
• 2014

In this research, we evaluated the performance and characteristics of carbon supported PtM (M = Ni and Y) alloy catalysts (PtM/Cs) synthesized by a modified polyol method. With the PtM/Cs employed as a catalyst for the oxygen reduction reaction (ORR) of cathodes in proton exchange membrane fuel cells (PEMFCs), their catalytic and ORR activities and electrical performance were investigated and compared with those of commercial Pt/C. Their particle sizes, particle distributions and electrochemically active surface areas (EAS) were measured by TEM and cyclic voltammetry (CV), while their ORR activity and electrical performance were explored using linear sweeping voltammetries with rotating disk electrodes and rotating ring-disk electrodes as well as PEMFC single cell tests. TEM and CV measurements show that PtM/Cs have the compatible particle size and EAS with Pt/C. When it comes to ORR activity, PtM/C showed the equivalent or better half-wave potential, kinetic current density, transferred electron number per oxygen molecule and $H_2O_2$ production(%) to or than commerical Pt/C. Based on results gained by the three electrode tests, when the PEMFC single cell tests were carried out, the current density measured at 0.6 V and maximum power density of PEMFC single cell adopting PtM/C catalysts were better than those adopting Pt/C catalyst. It is therefore concluded that PtM/C catalysts synthesized by modified polyol can result in the equivalent or better ORR catalytic capability and PEMFC performance to or than commercial Pt/C catalyst.

• Journal of the Korean Geotechnical Society
• /
• v.33 no.11
• /
• pp.21-34
• /
• 2017

The ground penetrating radar (GPR) signal can be measured with different amplitudes according to the directivity, so the directivity of the antenna should be considered. The objective of this study is to investigate the directivity of antenna by analyzing the reflection characteristics of electromagnetic waves radiated from the antenna, and to evaluate effective range of angle that can inspect an abnormal area according to the directivity of antenna. For the measurement of the directivity, a circular metal bar is used as reflector and the signals are measured by changing the angle and the distance between reflector and antenna in the E- and H-plane. The boundary distance between the near field and the far field is determined by analyzing the amplitudes of reflected signals, and two points with different distances from each of near and far fields are designated to analyze radiation patterns in near and far fields. As a result of radiation pattern measurement, in the near field, minor lobes are observed at angle section at more than $50^{\circ}$ in both E- and H-plane. Therefore, antenna has the directivity for the direction of main lobe and minor lobes in near field. In the far field, antenna has the directivity for a single direction of main lobe because minor lobes are not observed. The amplitude of the signal reflected from the near field is unstable, but it can be distinguished from noise. Therefore, in the near field, the ground anomaly can be detected with high reliability. On the other hand, the amplitude of the signal reflected from the far field is stable, but it is hard to distinguish between reflected signal and noise because of the excessive loss of electromagnetic wave. The analyses of directivity in the near and the far fields performed in this study may be effectively used to improve the reliability of the analyses of abnormal area.

• Korean Journal of Family Social Work
• /
• no.54
• /
• pp.297-331
• /
• 2016

The purpose of this study was to examine the mediating roles of neglectful rearing attitudes and mental health in the relationship between economic status of single-parent famillies and school adjustment, and the differences between single-parent and two-parent families, using structural equation modeling. Data were obtained from the Middle School 1 Panel(third-wave) of the Korean Child and Youth Panel Survey 2010. This study selected 2,195 middle school 3th-grade students (249 from single-parent families and 1,946 from two-parent families). Data were examined with structural equation modeling and multi-group analysis using AMOS 21.0, and mediating effects were tested using the Sobel test. The results were as follows; First, the single-parent children reported lower levels of economic status and school adjustment, and higher levels of neglectful rearing attitudes than the two-parent children. Second, multi-group analysis showed a statistically significant difference between single-parent and two-parent in structural equation modeling. Economic status of two-parent famillies affected school adjustment of children, but economic status of single-parent famillies did not affect school adjustment of children. Third, as a result of examining for total effect, the variable that most influenced school adjustment of children was neglectful rearing attitudes. Fourth, neglectful rearing attitudes and mental health did play a mediating role in the relationship between economic status and school adjustment in case of two-parent famillies, but neglectful rearing attitudes and mental health did not play a mediating role in case of single-parent famillies. Based on the result, this study stressed the following; First, the study suggested that problem of the single-parent famillies supporting standard which is concentrated on the low income single-parent famillies. Second, the study proposed multifaceted support measures which reflects characteristics of single-parent famillies to increase school adjustment of the single-parent children.

• Journal of the Korean earth science society
• /
• v.42 no.5
• /
• pp.479-495
• /
• 2021

This study investigates the synoptic (patterns of southern highs, northern lows, and lows rapidly developed by tropopause folding), thermodynamic, and kinematic characteristics of a strong wind that occurred in the Yeongdong region of South Korea on March 18-20, 2020. To do so, we analyzed data from an automatic weather station (AWS), weather charts, the European Centre for Medium-range Weather Forecasts (ECMWF) reanalysis, rawinsonde, and windprofiler radars. The daily maximum instantaneous wind speed, exceeding 20 m s^-1, was observed at five weather stations during the analysis period. The strongest instantaneous wind speed (27.7 m s^-1) appeared in the Daegwallyeong area. According to the analysis of weather charts, along with the arrangement of the north-south low-pressure line, the isobars were moved to the Yeongdong area. It showed a sine wave shape, and a strong wind developed owing to the strong pressure gradient. On March 19, in the northern part of the Korean Peninsula, with a drop in atmospheric pressure of 19 hPa or more within one day, a continuous strong wind was developed by the synoptic structure of the developing polar low. In the adiabatic chart observed in Bukgangneung, the altitude of the inversion layer was located at an altitude of approximately 1-3 km above the mountaintop, along with the maximum wind speed. We confirmed that this is consistent with the results of the vertical wind field analysis of the rawinsonde and windprofiler data. In particular, based on the thermodynamic and kinematic vertical analyses, we suggest that strong winds due to the vertical gradient of potential temperature in the lower layer and the development of potential vorticity due to tropopause folding play a significant role in the occurrence of strong winds in the Yeongdong region.

• Sleep Medicine and Psychophysiology
• /
• v.26 no.1
• /
• pp.44-48
• /
• 2019

Objectives: Insomnia is one of the most prevalent sleep disorders. Recent studies suggest that cognitive and physical arousal play an important role in the generation of primary insomnia. Studies have also shown that information processing disorders due to cortical hyperactivity might interfere with normal sleep onset and sleep continuity. Therefore, focusing on central nervous system arousal and normalizing the information process have become current topics of interest. It has been well known that neurofeedback can reduce the brain hyperarousal by modulating patients' brain waves during a sequence of behavior therapy. The purpose of this study was to investigate effects of neurofeedback therapy on electroencephalography (EEG) characteristics in patients with primary insomnia. Methods: Thirteen subjects who met the criteria for an insomnia diagnosis and 14 control subjects who were matched on sex and age were included. Neurofeedback and sham treatments were performed in a random order for 30 minutes, respectively. EEG spectral power analyses were performed to quantify effects of the neurofeedback therapy on brain wave forms. Results: In patients with primary insomnia, relative spectral theta and sigma power during a therapeutic neurofeedback session were significantly lower than during a sham session ($13.9{\pm}2.6$ vs. $12.2{\pm}3.8$ and $3.6{\pm}0.9$ vs. $3.2{\pm}1.0$ in %, respectively; p < 0.05). There were no statistically significant changes in other EEG spectral bands. Conclusion: For the first time in Korea, EEG spectral power in the theta band was found to increase when a neurofeedback session was applied to patients with insomnia. This outcome might provide some insight into new interventions for improving sleep onset. However, the treatment response of insomniacs was not precisely evaluated due to limitations of the current pilot study, which requires follow-up studies with larger samples in the future.

• Journal of the Microelectronics and Packaging Society
• /
• v.28 no.3
• /
• pp.1-7
• /
• 2021

In this paper, by embedding a bare-die chip-type drive amplifier into the PCB composed of ABF and FR-4, it implements an embedded active device that can be applied in 28 GHz band modules. The ABF has a dielectric constant of 3.2 and a dielectric loss of 0.016. The FR-4 where the drive amplifier is embedded has a dielectric constant of 3.5 and a dielectric loss of 0.02. The proposed embedded module is processed into two structures, and S-parameter properties are confirmed with measurements. The two process structures are an embedding structure of face-up and an embedding structure of face-down. The fabricated module is measured on a designed test board using Taconic's TLY-5A(dielectric constant : 2.17, dielectric loss : 0.0002). The PCB which embedded into the face-down expected better gain performance due to shorter interconnection-line from the RF pad of the Bear-die chip to the pattern of formed layer. But it is verified that the ground at the bottom of the bear-die chip is grounded Through via, resulting in an oscillation. On the other hand, the face-up structure has a stable gain characteristic of more than 10 dB from 25 GHz to 30 GHz, with a gain of 12.32 dB at the center frequency of 28 GHz. The output characteristics of module embedded into the face-up structure are measured using signal generator and spectrum analyzer. When the input power (P_in) of the signal generator was applied from -10 dBm to 20 dBm, the gain compression point (P_1dB) of the embedded module was 20.38 dB. Ultimately, the bare-die chip used in this paper was verified through measurement that the oscillation is improved according to the grounding methods when embedding in a PCB. Thus, the module embedded into the face-up structure will be able to be properly used for communication modules in millimeter wave bands.

• 한국사회정책
• /
• v.23 no.2
• /
• pp.49-81
• /
• 2016

This study agrees with the idea that a situation centered perspective provides a useful contribution in understanding women's attitude on organizations. Women's occupational experiences are less related to their "femaleness" than to the structural constraints inherent in the occupational positions women fill. So characteristics of the organizational situation including gender composition and hierarchical status may "shape and define" women's experience on the job. The present study examined the managerial level's gender gap and "glass ceiling" of the corporation. According to Kanter, if the ratio of women to men in organizations begins to shift, as affirmative action and new hiring and promotion policies promised, forms of relationships and corporate culture should also change. However, the mere presence of women on workplace may not, in itself, result in women-friendly work condition. This study analyzes "Korean Women Manger Panel survey(2010 3rd. wave)" to examine how much gender gap of the managerial level persists and when the glass ceiling effect emerges. Using t-test and ANOVA, various aspects of the gender gap within managerial level were verified. The most significant finding is the glass ceiling effect starts from very low level of management. Policy implications from the statistical analysis of the Panel survey are: 1) We need to increase the absolute number of the women managers for securing middle level women leadership pipe line. 2) We need to confront the fact that the glass ceiling starts from the very low managerial level, and to explore more realistic way to break up the vicious circle for the tokenism. and 3) We need to looking beyond numbers in approaching women's matter at work. At the cultural and institutional level, work-family programs and policies, women's ratings of their competence, and family-friendly organization's climate should be considered.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.29 no.5A
• /
• pp.565-575
• /
• 2009

In recent years, there have been numerous explosion-related accidents due to military and terrorist activities. Such incidents caused not only damages to structures but also human casualties, especially in urban areas. To protect structures and save human lives against explosion accidents, better understanding of the explosion effect on structures is needed. In an explosion, the blast load is applied to concrete structures as an impulsive load of extremely short duration with very high pressure and heat. Generally, concrete is known to have a relatively high blast resistance compared to other construction materials. However, normal strength concrete structures require higher strength to improve their resistance against impact and blast loads. Therefore, a new material with high-energy absorption capacity and high resistance to damage is needed for blast resistance design. Recently, Ultra High Strength Concrete(UHSC) and Reactive Powder Concrete(RPC) have been actively developed to significantly improve concrete strength. UHSC and RPC, can improve concrete strength, reduce member size and weight, and improve workability. High strength concrete are used to improve earthquake resistance and increase height and bridge span. Also, UHSC and RPC, can be implemented for blast resistance design of infrastructure susceptible to terror or impact such as 9.11 terror attack. Therefore, in this study, the blast tests are performed to investigate the behavior of UHSC and RPC slabs under blast loading. Blast wave characteristics including incident and reflected pressures as well as maximum and residual displacements and strains in steel and concrete surface are measured. Also, blast damages and failure modes were recorded for each specimen. From these tests, UHSC and RPC have shown to better blast explosions resistance compare to normal strength concrete.

• Journal of Korean Society of Coastal and Ocean Engineers
• /
• v.35 no.6
• /
• pp.109-120
• /
• 2023

The High-Frequency Radar (HFR) is an equipment designed to measure real-time surface ocean currents in broad maritime areas.It emits radio waves at a specific frequency (HF) towards the sea surface and analyzes the backscattered waves to measure surface current vectors (Crombie, 1955; Barrick, 1972).The Seasonde HF Radar from Codar, utilized in this study, determines the speed and location of radial currents by analyzing the Bragg peak intensity of transmitted and received waves from an omnidirectional antenna and employing the Multiple Signal Classification (MUSIC) algorithm. The generated currents are initially considered ideal patterns without taking into account the characteristics of the observed electromagnetic wave propagation environment. To correct this, Antenna Pattern Measurement (APM) is performed, measuring the strength of signals at various positions received by the antenna and calculating the corrected measured vector to radial currents.The APM principle involves modifying the position and phase information of the currents based on the measured signal strength at each location. Typically, experiments are conducted by installing an antenna on a ship (Kim et al., 2022). However, using a ship introduces various environmental constraints, such as weather conditions and maritime situations. To reduce dependence on maritime conditions and enhance economic efficiency, this study explores the possibility of using unmanned aerial vehicles (drones) for APM. The research conducted APM experiments using a high-frequency radar installed at Dangsa Lighthouse in Dangsa-ri, Wando County, Jeollanam-do. The study compared and analyzed the results of APM experiments using ships and drones, utilizing the calculated radial currents and surface current fields obtained from each experiment.

• Asia-Pacific Journal of Business Venturing and Entrepreneurship
• /
• v.16 no.3
• /
• pp.193-211
• /
• 2021

Recently, interest in Korean Wave craze and K-beauty, led by K-pop, is increasing. In addition, the popularity and influence of the domestic beauty service industry has increased, and the economic and cultural ripple effects have been continuously expanding. The need to professional manpower training in response to the demand for manpower due to the growing development of domestic beauty services is emphasized, and the number of trainees who are actual consumers of beauty academy is increasing. Therefore, the purpose of our study is to examine the importance of quality factors of educational services to achieve educational purposes in the educational services provided by the Beauty Academy and the relationship between relationship commitment and educational service performance. Furthermore, it is to draw the importance of administrative support services, educational programs as well as educational service provision activities. However, the research for professional manpower training according to the provision of beauty services is insufficient compared to the development speed of the beauty industry. Therefore, at the present time when beauty service education is emphasized, our study will examine the relationship between relationship commitment and educational service performance based on the quality of education service by the students of domestic beauty academy. The measurement variables set for our study are program, instructor quality, tuition, external service, service fairness, relationship commitment, trust level, and educational service performance. The variables were analyzed and derived through the survey, and the following contents were derived from the empirical analysis. First, the quality of education service provided by the beauty academy, such as program, external service, service fairness, relationship commitment and trust level, had a significant effect on relationship commitment. Educational services provided by the institute, such as the systematicity and diversity of educational programs, enabled students to have a uniform relationship commitment. The quality of education service itself is to learn the expertise necessary for providing beauty service from the standpoint of the students and play an organic role in the relationship with the institute. Second, the moderating effect of trust level between academies and students was significant in the quality of education service and the relationship commitment. This means that students will feel higher level of service quality through the practical trust relationship of the students about the educational services provided by the institute. Based on the results of the empirical analysis, the implications of our study are to find ways to improve the students' ability and satisfaction represented by the results of educational services. This is because the quality of education services provided by the institute called Beauty Academy will have a great impact on the career choice of educational facilities and students. The characteristics of consistency, convenience, and knowledge orientation of education itself should be considered comprehensively, and a strong market position should be established through image formation through external service factors, which are external environments of academies.Furthermore, in terms of presenting differentiated strategies with competitors, the educational service quality factors play a significant role in the commitment to the relationship with the students, so the role of relationship marketing will be important for the psychological stability experienced by the students by grasping the demand accompanying the behavior of the students in advance.