• Journal of Electrical Engineering and Technology
• /
• v.9 no.6
• /
• pp.2070-2078
• /
• 2014

In this work, the frequency response of gate-all-around (GAA) Ge/GaAs heterojunction tunneling field-effect transistor (TFET) with hetero-gate-dielectric (HGD) and pnpn channel doping profile has been analysed by technology computer-aided design (TCAD) device-circuit mixed-mode simulations, with comparison studies among ppn, pnpn, and HGD pnpn TFET devices. By recursive tracing of voltage transfer curves (VTCs) of a common-source (CS) amplifier based on the HGD pnpn TFET, the operation point (Q-point) was obtained at $V_{DS}=1V$, where the maximum available output swing was acquired without waveform distortion. The slope of VTC of the amplifier was 9.21 V/V (19.4 dB), which mainly resulted from the ponderable direct-current (DC) characteristics of HGD pnpn TFET. Along with the DC performances, frequency response with a small-signal voltage of 10 mV has been closely investigated in terms of voltage gain ($A_v$), unit-gain frequency ($f_{unity}$), and cut-off frequency ($f_T$). The Ge/GaAs HGD pnpn TFET demonstrated $A_v=19.4dB$, $f_{unity}=10THz$, $f_T=0.487$ THz and $f_{max}=18THz$.

• Membrane Journal
• /
• v.15 no.2
• /
• pp.132-140
• /
• 2005

The effects of electrical fields on the efficiencies in ultrafiltration for protein separation were explored. The experiments were proceeded under constant transmembrane pressure (THP) using protein (albumin and lysozyme) solutions. For ultrafiltrations, cellulose membranes with molecular weight cut off (MWCO) 30 kDa were used. It is found that electrical field improved the filtration flux of albumin solution. The electrical field showed another interesting effect for filtration of protein solution. Depending on the electrical charges of protein molecules, the electrical field promoted or hindered the permeation of proteins through membranes. With the effect of electrical field, not only the permeation flux but also the selectivity of ultrafiltration could be improved.

• Journal of the Korean Geotechnical Society
• /
• v.36 no.1
• /
• pp.29-38
• /
• 2020

These days the circular cross section cofferdam has been frequently used for the earth retaining structures or cut off wall such as ventilating opening, intake tower in cofferdam, shaft for emergency. By the arching effect, the circular cross section type cofferdam has more advantage than a polygon cofferdam in terms of the structural forces and moment. This paper shows the proper approach to analyze the circular cross section cofferdam using 2D Finite Element Method (FEM) for the circular stiffener (ring beam) evaluation. Besides, the various shapes of cofferdam indluding circular cross section have modeled the 3D Finite Element Mothod (FEM). The circular cross section cofferdam shows the minimum reaction force compared with the other shapes of cofferdam.

• Nutrition Research and Practice
• /
• v.17 no.2
• /
• pp.330-340
• /
• 2023

BACKGROUND/OBJECTIVES: Emotional eating is one of the eating behaviors in which negative emotions affect eating. During the luteal phase, premenstrual syndrome (PMS) and its associated psychological and physical symptoms can appear in some women, and a few of them suffer from premenstrual dysphoric disorder (PMDD), a severe form of PMS. Some women diagnosed with PMS/PMDD experience emotional eating during the luteal phase, which may be a coping mechanism for psychological stress. This study aimed to investigate how PMS/PMDD and negatively perceived stress are related to emotional eating. SUBJECTS/METHODS: A total of 409 women aged 20 to 39 yrs with a body mass index (BMI) ranging from 18.5 to 29.9 kg/m² participated in this study. Participants who responded to all the questions of the Shortened Premenstrual Assessment Form, Negative Perceived Stress Scale, and Emotional Eater Questionnaire were divided into a PMDD and a non-PMDD group according to the cut-off value for PMDD diagnosis. Independent t-tests and mediation analyses were performed to compare the 2 groups. RESULTS: No significant differences between the 2 groups were found in terms of BMI; however, the average values for emotional eating, PMS, and negative perceived stress of the PMDD group were significantly higher than those of the non-PMDD group. Only negative perceived stress had a significant effect on emotional eating in the non-PMDD group. In the PMDD group, PMS was statistically significant for both negative perceived stress and emotional eating mediated by negative perceived stress. Consequently, it appeared to have a partial or complete mediation depending on the independent variable for the PMDD group. CONCLUSIONS: This study highlights the importance of managing negative perceived stress to control emotional eating in PMS/PMDD for improved women's health.

• Korean Journal of Environment and Ecology
• /
• v.29 no.4
• /
• pp.590-598
• /
• 2015

Despite various control methods for pine wilt disease, the disease has been increasing at an alarming rate every year in Korea. Still there is a lack of research on the problems of the current methods used to curb the disease. One main method to control pine wilt disease is fumigation for eliminating the larva of the pine sawyer beetle (Monochamus alternatus) which is known as the vector insect for pine wilt disease. We surveyed and analyzed the amount of destroyed uninfected trees in the fumigated area by studying 32 survey plots ($100m^2$) in Miryang city. The destroyed trees' crown area was estimated by induced regression between root collar area and crown area of the remaining trees (coniferous tree: $R^2=57.4$, deciduous broad-leaved tree: $R^2=63.8$). According to the analysis results, the infected trees (cut trees) were 18.7% and cut trees which were not infected were 35.5% of the total tree population of the study area on the basis of total crown area. In case of pine trees, 8.4% of uninfected trees were cut off but 62% of uninfected deciduous broad-leaved trees including Quercus spp. were affected and damaged during the fumigation process. Since these broad-leaved trees dominate the sub-canopy layer of the forest, this indiscriminate interruption of broad-leaved trees has the adverse effect of depriving the public benefits such as shadow, a cooler weather, controlling humidity, etc.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.37 no.11
• /
• pp.1349-1354
• /
• 2013

Sealing structure to prevent flowing hot gas into the driving device, located between the driving shaft and the liner of On-Off valve for controlling the hot gas flow path was studied. Wear occurs due to the constant movement of the driving shaft controlled by actuator on graphite as the sealing material. In this paper, the dynamic wear behavior in high temperature of graphite(HK-6) to be used as sealing material was evaluated. Reciprocating wear test was carried out for the graphite(HK-6) to the relative motion between shaft materials(W-25Re). The results of friction coefficient and specific wear rate according to contact load, sliding speed at room temperature and $485^{\circ}C$ considering the actual operating environment were evaluated. Through the SEM analysis of the worn surface, third body as lubricant films were observed and lubricant effect of third body was considered.

• Journal of Korean Academy of Nursing
• /
• v.44 no.1
• /
• pp.55-63
• /
• 2014

Purpose: This study was conducted to examine the late effects, social adjustment, and quality of life in adolescents who had been completely treated for childhood leukemia and their parents. Methods: Participants consisted of 41 pairs of adolescent survivors (13-18 years) and their parents. Parents checked for their child's physical late effects. The Korean Version of Post-Traumatic Symptoms for psychological late effects, social functioning questionnaire for social adjustment and the PedsQL 4.0 Generic Core Scales for quality of life were completed by adolescents and parents. Data were analyzed using SPSS. Results: Twenty out of 41 adolescents had one or more physical late effects. Adolescents showed more serious psychological late effect than parents. Five children and seven parents had above cut-off scores and they were considered the high risk group for posttraumatic symptoms. Parent-reported scores were significantly higher than child-reported scores in terms of social adjustment and emotional functioning of quality of life. Low school functioning in adolescents was associated with physical late effects. Conclusion: The results indicate that long-term and systematic management for childhood leukemia survivors affect positive social adjustment and can further improve quality of life.

• Korean Journal of Soil Science and Fertilizer
• /
• v.46 no.6
• /
• pp.585-592
• /
• 2013

To estimate the effect of long-term fertilization on metabolically active bacterial communities in a rice field, RNA was extracted from endosphere (rice root), rhizosphere, and bulk soil that had been subjected to different fertilization regimes for 59 years, and the 16S rRNAs were analyzed using the pyrosequencing method. The richness and diversity of metabolically active bacteria were higher in bulk soil than in the endosphere and rhizosphere, and showed no significant difference between non-fertilized and fertilized plots. Weighted UniFrac analysis showed that each compartment had characteristic bacterial communities and that the effect of long-term fertilization on the structure of bacterial community was more pronounced in bulk soil than in the endosphere and rhizosphere. The 16S rRNAs affiliated with Alphaproteobacteria and Firmicutes were more abundant in the endosphere than in bulk soil while those affiliated with Chloroflexi and Acidobacteria were more abundant in bulk soil than in the endosphere. Several dominant operational taxonomic units (clustered at a 97% similarity cut-off) showed different frequencies between non-fertilized and fertilized plots, suggesting that the fertilization affected their activities in the rice field.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.8 no.1
• /
• pp.141-150
• /
• 1988

Damping characteristics of chemically treated solls were studied by the use of FFT Analyzer and Bandwidth method. Also Modal Analysis was performed for the solidified silty sand samples. The soil samples were made of gravelly sand, sand, and silty sand, treated by water-glass chemical grouts. As the result of the study, it was found that the chemical grouting could be used for the vibration diminutinn effect as well as cut-off effect and strength improvement by the fact that the damping ratio of chemically treated soils was highly increased as the damping ratio of solidified soil was 0.11~0.22 and rathier high values in compare with the damping ratio of common soils which was 0.01~0.10.

• The Journal of Korean Physical Therapy
• /
• v.28 no.2
• /
• pp.149-154
• /
• 2016

Purpose: The aim of this study is to suggest an intervention method for clinical use in the future by analyzing the effect of breathing exercise on activity of sternocleidomastoid muscle and scalenus anterior muscle, which are respiratory synergist muscles, and pulmonary functions in patients with forward head posture. Methods: Prior to the experiment, 12 patients (experimental group) performed feedback exhalation exercise along with conventional deep neck exercise, and 11 subjects (control group) performed feedback deep neck exercise along with conventional deep neck exercise. The intervention programs were performed for 40 minutes once a day (three times a week for four weeks). Results: Before intervention, %RMS was measured for surface electromyography (sEMG), and FVC, FEV1, and FEV1/FVC were measured using a spirometer. After four weeks, these items were re-measured under the same condition and analyzed. In within-group comparison of the experimental group, activity of sternocleidomastoid muscle and scalenus anterior muscle showed a significant decrease (p<0.05)(p<0.001), and forced vital capacity (FVC) showed a significant increase (p<0.05). In within-group comparison of the control group, activity of sternocleidomastoid muscle and scalenus anterior muscle showed a significant decrease (p<0.05), and in between-group comparison, there were significant differences in activity of sternocleidomastoid muscle and FVC (p<0.05). Conclusion: Long-term forward head posture restrains exercise performance of the neck and leads to exercise avoidance of the neck during daily activities, thus restraint factors might be created even while breathing. To cut off this link, a constant effort is required and diversified research on the correlation between neck functions and breathing should be conducted.