• Journal of Korean Society of Environmental Engineers
• /
• v.32 no.8
• /
• pp.739-746
• /
• 2010

The purposes of this study are 1) to develop an advanced chamber system within ${\pm}10%$ of air velocity at the particulate matter (PM) collection area, 2) to research theoretical characteristics of PM10 and PM2.5 samplers, 3) to assess the performance characteristics of PM10 and PM2.5 samplers through chamber experiments. The total six one-hour experiments were conducted using the cornstarch with an mass median aerodynamic diameter (MMAD) of $20\;{\mu}m$ and an geometric standard deviation of 2.0 at the two different air velocity conditions of 0.67 m/s and 2.15 m/s in the chamber. The aerosol samplers used in the present study are one APM PM10 and one PM2.5 samplers accordance with the US federal reference methods and specially designed three mini-volume aerosol samplers (two for PM10 and one for PM2.5). The overall results indicate that PM10 and PM2.5 mini-volume samplers need correction factors of 0.25 and 0.39 respectively when APM PM samplers considered as reference samplers and there is significant difference between two mini-volume aerosol samplers when a two-way analysis of variance is tested using the measured PM10 mass concentrations. The PM10 and PM2.5 samplers with the cutpoints and slopes (PM10: $10{\pm}0.5\;{\mu}m$ and $1.5{\pm}0.1$, PM2.5: $2.5{\pm}0.2\;{\mu}m$ and $1.3{\pm}0.03$) theoretically collect the ranges of 86~114% and 64~152% considering the cornstarch characteristics used in this research. Furthermore, the calculated mass concentrations of PM samplers are higher than the ideal mass concentrations when the airborne MMADs for the cornstarch used are smaller than the cutpoints of PM samplers and the PM samplers collected less PM in another case. The chamber experiment also showed that PM10 and PM2.5 samplers had the bigger collection ranges of 37~158% and 55~149% than the theocratical calculated mass concentration ranges and the relatively similar mass concentration ranges were measured at the air velocity of 2.15 m/s comparing with the 0.67 m/s.

• Journal of dental hygiene science
• /
• v.16 no.6
• /
• pp.432-441
• /
• 2016

This study was conducted to investigate the effects of professional oral healthcare program in eldery residents long-term care facilities. Ninety-four elderly residents from 5 different facilities in Asan participated in this study. The subjects were divided into 3 groups, with 32 in experimental group I, 30 in experimental group II, and 32 in the control group. Subjects in experimental group I were treated by a dental hygienist with professional oral healthcare and received daily oral care from caregivers who had completed elderly oral healthcare course. Subjects in experimental group II received daily oral care from caregivers who had completed elderly oral healthcare course. Control group received daily oral care from caregivers. These 3 groups were tested for dental plaque, halitosis, tongue coating, and salivary flow at baseline, and after 4 and 12 weeks of treatment. There were significant differences in the dental plaque index between the groups, mediate times, and mediate methods, in halitosis between the mediate methods, and in tongue coating between the mediate times, as well as the mediate methods. Finally, salivary flow was significantly different with regard to mediate methods between experimental group II and the control group. Therefore, to improve the oral health condition of elderly residents, involvement of a part-time dentist and scheduled professional oral healthcare are necessary. Furthermore, elderly oral healthcare education for nursing staff, including managers, should be provided.

• Journal of the Korean Society for Nondestructive Testing
• /
• v.26 no.5
• /
• pp.297-305
• /
• 2006

The thermal ratcheting deformation at the reactor baffle and upper internal structure of the liquid metal reactor (LMR) can occur due to movement of the hot sodium free surface. In in-service inspection of reactor internals of LMR, a new inspection technique should be developed for the detection of the thermal ratcheting damage. In this study, an inspection technique using ultrasonic guided wave is proposed for the detection of the thermal ratcheting damage of cylindrical vessels. A 316L stainless steel cylindrical shell specimen has been prepared. The thermal ratchet structural tests were cyclically performed by heat-up up to $550^{\circ}C$ with steep temperature gradients along the axial direction after cool-down by cooling water. Ultrasonic guided wave propagation has been characterized by analysis of dispersion curve of the stainless steel plate. The zero-order antisymmetric $A_0$ guided wave has been selected as the optimal mode for detection of the ratcheting deformation. It is confirmed that the thermal ratcheting deformation can be detected by the measurement of transit time difference of circumferentially propagated $A_0$ guided waves.

• Korean Journal of Optics and Photonics
• /
• v.16 no.6
• /
• pp.535-541
• /
• 2005

We report on the development of a passively mode-locked near-infrared femtosecond laser with Cr:YAG crystal that operates near room temperature. The laser wavelength could easily be tuned by using only the internal prism pair over 110 nm from 1400 nm to 1510 nm in cw and over about 30 nm in mode-locked operation, respectively Maximum cw output powers of 810 mW were obtained with $1.5 \%$ output coupler for absorbed pump powers of 7.6 W. For compensation of the internal group velocity dispersion, an IR graded prism pair was used. The Cr:YAG laser delivered nearly Fourier-transform limited pulses with a pulse duration as short as 64 fs at 100 MHz repetition rate. In the mode-locked regime, the laser was operating at 1510 nm with a spectral bandwidth of 44 nm. In order to avoid unstable mode-locking and power instabilities, self-built tubes were inserted into the beam path in the resonator and purged with N2 gas. Finally, output powers of the Cr:YAG laser were optimized to 250 mW fer long time stable mode-locked operation.

• Journal of the Korea Convergence Society
• /
• v.7 no.2
• /
• pp.101-107
• /
• 2016

The purpose of this study was to determined the converge effects of weight-bearing exercise on lumbar, femur neck BMD and body compositions in intellectual disabilities and normal men. Nineteen men were participated for this study, they are divided into two groups(intellectual disabilities, n=9, and normal men, n=10). All subjects are accomplished on weight-bearing exercise (music rope-jumping) program for 60 minutes a day, 3 days a week throughout 12 weeks. Two-way ANOVA with repeated measures was used to determine differences between and within the intellectual and normal groups for dependent variables. The statistically significant level was set at 0.05. In this study, there were a significant differences on the bone mineral density of lumbar and femur neck level after exercise training in both groups (respectively p<.01, p<.001). Also, I found that there were effectively decreased on body weight, percent of body fat, and BMI levels after exercise training for 12 weeks in both groups (respectively p<.001). Therefore, music rope-jump exercise program may suggested to be one of the ideal training methods for enhancing and the convergence positive effect of bone mineral density and body compositions in intellectual and normal person.

• 한국체육학회지인문사회과학편
• /
• v.54 no.1
• /
• pp.553-566
• /
• 2015

This study was performed to identify the effects of different intensities of regular aerobic exercise on erythropoietin (EPO) and BDNF levels, and cognitive function and working memory in middle-aged women. Women aged 40 to 60 years residing in G-gu, Y-si, Gyeonggi-do were divided into 3 groups: control group, moderate-intensity aerobic exercise group and high-intensity aerobic exercise. All groups were asked to exercise at the given intensities, twice a week for a total of 12 weeks. Blood samples were collected from participants on week 0 (before exercising), week 6 and week 12, and then cognitive function and working memory tests were followed to measure erythropoietin (EPO) and BDNF levels, cognitive function and working memory. Repeated measures ANOVA, univariate analysis and follow-up test were performed on all data to compare the group, period and interaction through a SPSS. As a result, a significant difference over time was observed in EPO, BDNF, cognitive function and working memory; therefore, a follow-up one-way ANOVA analysis was performed on each group. As a result of analysis, a significant increase in erythrocyte, hematocrit, BDNF level and working memory was observed in moderate-intensity aerobic exercise group while erythrocyte and working memory were significantly increased inhigh-intensity aerobic exercise group. When comparing the results between the groups, the level of hematocrit was shown to be significantly higher in both moderate-and high-intensity aerobic group than the control group and also the higher level of hemoglobin was observed in both moderate-and high-intensity aerobic group comparing to control group. Considering the results of this study, therefore, a 12-week long aerobic exercise at moderate to high intensity positively affected EPO and BDNF levels, cognitive function and working memory in middle-aged women.

• Journal of Korean Home Economics Education Association
• /
• v.19 no.4
• /
• pp.201-218
• /
• 2007

This study is a quasi-experimental study to find out the effect of school library-assisted instruction on middle school students' self-directed learning ability in Home Economics Education. For this purpose, the following research questions were established. 14 hours of school library-assisted instruction and traditional lecture were carried out to 164 9th grade female students(82 of experimental group, 82 of comparison group) of a girls' middle school in Jinju, Gyeongnam. To verify the instructional effect, a pre-test and a post-test for self-directed learning ability were carried out. SPSS 12.0 was used for statistical analysis. For statistical analysis, reliability analysis, frequency analysis, x2-test, t-test, repeated measures-ANOVA, and bivariate analysis were used. The results of this research were as follows: First, there was a statistically significant difference between experimental group and comparison group in the self-directed learning ability in all the subordinate items. Second, the change of self-directed learning ability by grade within the experimental group showed no interactional effect in all the sub-items except problem solving ability. Problem solving ability showed a meaningful difference in the rate of grade rising in accordance with academic achievement level and a higher synergy effect was shown in the low academic achievement group. Third, the experimental group showed a higher rate of rising in the self-directed learning ability than the comparison group, and the low academic achievement group showed a higher rising rate of grade than the high academic achievement group. Based on the results of this research, we concluded that the school library-assisted instruction was effective in enhancing middle school students' self-directed learning ability especially for the low academic achievement group.

• Journal of Chest Surgery
• /
• v.32 no.9
• /
• pp.773-780
• /
• 1999

Background: It has been demonstrated that brief periods of calcium depletion and repletion (calcium-free preconditioning, CP) have cardioprotective effects as seen in ischemic preconditioning(IP) which enhances the recovery of post-ischemic contractile dysfunction and reduces the incidence of reperfusion-induced arrhythmia or infarct size after a prolonged ischemia. In the present study, we tested this paradoxical phenomenon in isolated rabbit hearts. Material and Method: Hearts isolated from New Zealand white rabbits(1.5∼2.0 Kg body weight) were perfused with Tyrode solution using the Langendorff technique. After stabilizing the baseline hemodynamics, the hearts were subjected to 45 minutes of global ischemia followed by 120 minutes of reperfusion with IP(IP group, n=7) or without IP (ischemic control group, n=7). IP was induced by a single episode of 5 minutes global ischemia and 10 minutes reperfusion. In the CP group(n=7), the hearts were subjected to perfusion with Tyrode solution with calcium depletion for 5 minutes and repletion for 10 minutes, and 45 minutes of ischemia and 120 minutes of reperfusion. Left ventricular function including developed pressure, dP/dt, heart rate, left ventricular end-diastolic pressure and coronary flow was measured. Infarct size was determined by staining with 1% triphenyltetrazolium chloride and planimetry. Data were analyzed by a one-way analysis of variance and Tukey's post-hoc test. Result: In comparison with the ischemic control group, IP significantly enhanced the recovery of the left ventricular function including the left ventricular developed pressure, contractility, and coronary flow; in contrast, these functional parameters of the CP group tended to be lower than those of the ischemic control group. However, the infarct size was significantly reduced by IP or CP(p<0.05). Conclusion: These results suggest that in isolated Langendorff-perfused rabbit heart model, CP(induced by single episode of 5 minutes calcium depletion and 10 minutes repletion) could not improve the post-ischemic contractile dysfunction(after a 45-minute global ischemia) but it has an infarct size-limiting effect.

• The Journal of Korean Society for Radiation Therapy
• /
• v.26 no.1
• /
• pp.83-89
• /
• 2014

Purpose : In case of the intensity modulated radiation therapy (IMRT) using Tomotherapy and linear accelerator (Linac), it was to compare and to evaluate the imaging dose of MVCT and CBCT that were performed daily for the correct set up of the patient. Materials and Methods : The human body model Phantom (Anderson rando Phantom, USA) was divided into the three parts as Head, Thorax, pelvis, and after GafChromic EBT3 film cut to the size of $0.5{\times}0.5cm2$.in the center of the recording area were situated on the ant, post, left, and right surface of the phantom and 2cm in depth from the ant, post, left, right, and center surface of the phantom, the surface dose and inner dose were measured repeatedly three times, respectively, using the tomotherapy (Hi Art) and the OBI of NovalisTx. The measured film calculated the output value by RIP version6.0 and then the average value of the dose was calculated by the one-way analysis of variance. Results : Using the human body model phantom, the results of MVCT and CBCT performance were that measurements of MVCT inner dose were showed $15.43cGy{\pm}6.05$ in the head, $16.62cGy{\pm}3.08$ in the thorax, $16.81cGy{\pm}5.24$ in the pelvis, and measurements of CBCT inner dose were showed $13.28{\pm}3.68$ in the head, from $13.66{\pm}4.04$ in the thorax, $15.52{\pm}3.52$ in the pelvis. The measurements of surface dose were showed in case of MVCT performance, $11.64{\pm}4.05$ in the head, $12.16{\pm}4.38$ in the thorax, $12.05{\pm}2.71$ in the pelvis, and in case of CBCT performance, $14.59{\pm}3.51$ in the head, $15.82{\pm}2.89$ in the thorax, $17.48{\pm}2.80$ in the pelvis, respectively. Conclusion : In case of Inner dose, the MVCT using MV energy showed higher than the CBCT using kV energy at 1.16 times in the head, at 1.22 times in the thorax, at 1.08 times in the pelvis, and in case of surface dose, the CBCT was higher than MVCT, at 1.25 times in the head, at 1.30 times in the thorax, at 1.45 times in the pelvis. Imaging dose was a small amount compared to the therapeutic dose but it was thought to affect partially to normal tissue because it was done in daily schedule. However, IMRT treatment was necessarily parallel with the IGRT treatment through the image-guide to minimize errors between planned and actual treatment. Thus, to minimize imaging dose that the patients receive, when planning the treatment, it should be set up a treatment plan considering imaging dose, or it must be performed by minimizing the scan range when shooting MVCT.

• Journal of the Korean Applied Science and Technology
• /
• v.37 no.4
• /
• pp.870-877
• /
• 2020

The purpose of this study is to compare and analyze the effects of stepping-in-place tempo and roundhouse kick types on response time. Fifteen males participated in this experiment. All have over ten years of experience and hold a forth dan(degree) black belt in taekwondo. The task is when the participants are doing stepping in place they respond to the light stimulus as fast as they can do roundhouse kick. Five different stepping in place tempos (100, 120, 140, 160, and 180 bpm) and four different types of roundhouse kick(front leg body roundhouse kick, front leg head roundhouse kick, back leg body roundhouse kick, and back leg head roundhouse kick) were used. Three measurements were taken for each of the different combinations of conditions for a total of 60 measurements. For data analysis, two-way ANOVA with repeated measures was used and pair-wise comparisons were performed using bonferroni statistics. The results show that there was significant difference interaction effect between stepping in place tempo and roundhouse kick type in the response time. And, there were significant difference in main effect of response time in accordance with stepping in place tempo and roundhouse kick type. The response time of roundhouse kick was the fastest at 160 bpm of stepping in place tempo, but there was no significant difference between 140 and 160 bpm. Front leg body roundhouse kick was the fastest. And, the response time was the fastest when front leg body roundhouse kicked at 140 bpm of stepping in place tempo. Stepping in place tempo between 140 and 160 bpm is the most effective to optimize the response time. And, More effective response time was front leg roundhouse kick as compared with back leg roundhouse kick and, body roundhouse kick as compared with head roundhouse kick. The findings in this study will provide useful information for performance improvement and will help with strategy for taekwondo competition.