• Journal of the Computational Structural Engineering Institute of Korea
• /
• v.31 no.2
• /
• pp.115-120
• /
• 2018

This paper introduces a magnetic hysteresis monitoring result to apply an EM sensing technique for estimating tensile force of PSC girder to various class of PS tendon. The tensile force of PS tendon is a very important factor in the performance evaluation of PSC bridges. However, in this time, the tensile force was just measured only during construction and it does not monitored after construction. To measure the tensile force of PS tendons, the EM sensing based NDT method was developed but the proposed method cannot be applied to various class of PS tendons. Thus this study performed the magnetic hysteresis measurement according to the tensile force for class B, C and D PS tendons through experimental study. The specific tensile forces(50, 100, 150, 180kN) were induced to the each specimens and the magnetic hysteresis curve was measured at each point. The permeability of specimens were gradually decreased according to increase of tensile force. Especially, the slopes of permeability variation of class B and C were similar while that of class D was different.

• The Journal of Korean Obstetrics and Gynecology
• /
• v.27 no.3
• /
• pp.1-11
• /
• 2014

Objectives: Hwangryunhaedok-tang (HH) is a representative heat clearing multiherb prescription. We evaluated the protective effect of HH against heat stress exposure in mice. Methods: Six weeks old ICR mice were used for this study. After $43^{\circ}C$ heat stress for 15 minutes, we evaluated the changes of motor activity and c-fos expression level to determine the proper heat stress and evaluation time. The subjects were divided into 4 groups (1. control group, 2. heat stress group with normal saline, 3. heat stress group with administration of 100 mg/kg, and 4. heat stress group with administration of 1000 mg/kg). After oral administration of HH once a day for 3 days, 2, 3, 4 groups were exposed to $43^{\circ}C$ heat stress for 15 minutes. Then, we evaluated the motor activity for 120 minutes and analyzed the c-fos expression using western blot. We investigated the effect of HH and its ingredients on c-fos expressions after heat stress. The mice were administrated HH, Scutellariae Radix, Coptidis Rhizoma, Phellodendri Cortex, and Gardeniae Fructus for 3 days. After one hour of last treatment, the mice were exposed to heat stress at $43^{\circ}C$ for 15 min. After two hours, the hypothalamus was dissociated and lysed to measure c-fos expression. Results: After oral administration of HH for 3 days, motor activity was recovered insignificantly. 100 mg/kg HH treatment reduced the c-fos expression after heat stress but insignificantly. Among the ingredients of HH, Coptidis Rhizoma and Scutellariae Radix treatment groups significantly reduced the c-fos after stress. Conclusions: These results show that Hwangryunhaedok-tang may be effective to reduce the heat stress response.

• Journal of Korean Physical Therapy Science
• /
• v.30 no.1
• /
• pp.10-22
• /
• 2023

Background: The purpose of this study was to investigate the effect of brain education-based exercise and KPEM manual therapy integrated program on the sleep and quality of life of cancer patients. Design: Seventy subjects who were diagnosed with cancer and were undergoing treatment volunteered to participate in this study. All subjects used a nonequivalent control group pretest-posttest design for either the experimental group or the control group. In the final analysis, there were 25 subjects in the experimental group and 18 subjects in the control group. Methods: For 12 weeks, the experimental group performed brain education-based exercise (20 minutes) and KPEM manual therapy (50 minutes), and the control group performed basic physical therapy and autonomous exercise. For evaluation, the Korean version of the Pittsburgh Sleep Quality Index (PSQI-K) and the quality of life index were measured after intervention using the European Organization for Research and Treatment of Cancer (EORTC-3.0Ver). Effect between groups, time effect over time, and group^*time interaction were analyzed through a pre-test before and after the 12-week intervention period, and repeated measure ANOVA after 12 weeks of the integrated program intervention. All statistical significance levels were set at α=.05. Results: The PSQI in the time effect (p=.001) and the group^*time interaction (p<.001) were statistically significant. In terms of EORTC, QL2 and PF2 were significant in time effect (p=.024; p=.021) and group^*time interaction (p=.007; p=.021), whereas in RF2, significance was only found in group^*time interaction (p=.028). In symptom indicators, time effect was the only significant factor in FA, SL, AP, and CO, respectively (p=.002; p=.028; p=.041; p =.005) and in DY, there were significant differences in the time effect (p=.016) and group^*time interaction (p=.002). Conclusion: The brain education-based exercise and KPEM manual therapy integrated program effectively improves the sleep and quality of life of cancer patients. It is considered that this exercise and therapy can be actively used as a psychological, emotional, and physically complementary physical therapy intervention to improve the quality of life of cancer patients.

• Journal of the Society of Disaster Information
• /
• v.19 no.3
• /
• pp.572-581
• /
• 2023

Purpose: The purpose of this study is to improve the irregularity of the stress-strain curve and to ensure accuracy when calculating the damping effect by preventing members from moving in the off-plane direction due to eccentricity when loads are applied. Method: The specifications of the steel strips used in this study are the same, but the curvature of the strips to constitute each damper is different. Each steel strip with different curvature was arranged in an triangle, three dampers with different curvature were made, and repeated load tests were conducted, and the amount of energy dissipation was calculated to measure the performance of the damper. Result: The amount of energy dissipation significantly decreases compared to the case where there is no initial curvature, and the change in the test energy dissipation amount according to the size of the curvature is not large, and the presence or absence of the hyperbolic rate is considered an important variable. Conclusion: The period is about 78.7% longer from T=0.3 to T=0.536sec, and the response spectrum acceleration is reduced from Sa=0.54g to Sa=0.229g, so the damping effect of the damper is sufficient.

• Journal of Korean Society of Occupational and Environmental Hygiene
• /
• v.33 no.2
• /
• pp.115-125
• /
• 2023

Objectives: This study was conducted to measure the level of radon in the air at a highway tunnel construction site in a gneiss area using the New Austrian Tunneling Method (NATM) and to evaluate exposure levels by occupation. Methods: Radon concentrations in the air were measured using E-PERM at points 300 m, 600 m, and 900 m from the tunnel entrance during the excavation and waterproofing work inside the tunnel. In addition, radon concentrations were measured during external excavation to compare with the inside of the tunnel. Personal exposure levels for major occupations including tunnel workers, construction equipment operators, waterproofers, shotcrete workers, and safety and health managers who participated in the construction were estimated using radon concentration measured in the work process area and working hours by occupation. Results: As a result of a total of 77 radon measurements, the geometric mean (GM) concentration was 71.1 Bq/m³, and the maximum concentration was 127.3 Bq/m³, which was below the indoor air quality criteria. Radon concentration by process decreased in the order of the tunnel excavation process (GM= Bq/m³, GSD=1.2), waterproofing process (GM=73.35 Bq/m³, GSD=1.2), and outside excavating process (GM=45.28 Bq/m³, GSD=1.2). Processes inside the tunnel were significantly higher than outside excavating processes (p<0.05). There was no statistically significant difference in radon concentration measured inside by distance from the tunnel entrance, but the innermost point of the tunnel, 900 m (GM=79.24 Bq/m³, GSD=1.27), measured the highest. Conclusions: The occupation with the highest individual exposure to radon was tunnel worker (64.16 Bq/m³), followed by construction equipment driver (64.04 Bq/m³) and waterproofer (63.13 Bq/m³).

• Journal of the Computational Structural Engineering Institute of Korea
• /
• v.37 no.3
• /
• pp.217-224
• /
• 2024

This paper proposes an efficient dimension reduction method (DRM) that considers the nonlinearity of the performance functions in reliability-based design optimization (RBDO). The dimension reduction method evaluates the reliability more accurately than the first-order reliability method (FORM) using integration quadrature points and weights. However, its efficiency is hindered as the number of quadrature points increases owing to the need for an additional evaluation of the performance function. In this study, we assessed the nonlinearity of the performance function in RBDO and proposed criteria for determining the number of quadrature points based on the degree of nonlinearity. This approach suggests adjusting the number of quadrature points during each iteration of the RBDO process while maintaining the accuracy of theDRM while improving the computational efficiency. The nonlinearity of the performance function was evaluated using the angle between the vectors used in the maximum probable target point (MPTP) search. Numerical tests were conducted to determine the appropriate number of quadrature points according to the degree of nonlinearity. Through a 2D numerical example, it is confirmed that the proposed method improves the efficiency while maintaining the accuracy of the dimension reduction method or Monte Carlo Simulation (MCS).

• Journal of the Institute of Electronics Engineers of Korea CI
• /
• v.48 no.4
• /
• pp.35-42
• /
• 2011

Link quality assessment is a crucial part of sensor network formation to stably operate large-scale wireless sensor networks (WSNs). A stability of path consisting of several nodes strongly depends on all link quality between pair of consecutive nodes. Thus it is very important to assess the link quality on the stage of building a routing path. In this paper, we present a link quality assessment method, Hybrid Link Quality Metric (HQLM), which uses both of LQI and RSSI from RF chip of sensor nodes to minimize set-up time and energy consumption for network formation. The HQLM not only reduces the time and energy consumption, but also provides complementary cooperation of LQI and RSSI. In order to evaluate the validity and efficiency of the proposed method, we measure PDR (Packet Delivery Rate) by exchanging multiple messages and then, compare PDR to the result of HQLM for evaluation. From the research being carried out, we can conclude that the HQLM performs better than either LQI- or RSSI-based metric in terms of recall, precision, and matching on link quality.

• Journal of Korean Society for Atmospheric Environment
• /
• v.25 no.5
• /
• pp.459-471
• /
• 2009

Air Monitoring Network(11 urban stations) is operated to measure ambient air quality in Daegu city. The urban air monitoring stations include 6 in residence area, 3 in industrial area, 1 in commercial area, and 1 in green area. In this study, hourly data (2006. 1. 1~2008. 12. 31) of $PM_{10}$ were measured at 11 urban air monitoring stations. $PM_{10}$ mean concentrations were high in fall and winter because of low wind speed and many haze days. The number of exceeding the daily standard of $PM_{10}$ in industrial area was approximately twice as many as that in residence area. $PM_{10}$ concentrations and visibility were influenced significantly by wind speed. Wind speed and visibility were below 1.8 m/s and 10 km, respectively when $PM_{10}$ concentrations were over $120{\mu}g/m^3$. $PM_{10}$ concentrations were high when haze was observed. The mean concentrations of $PM_{10}$ were $104{\pm}41.3{\mu}g/m^3$, $63{\pm}35.1{\mu}g/m^3$, and $49{\pm}26.9{\mu}g/m^3$, respectively when haze, mist and clear were observed.

• Journal of Korean Society of Steel Construction
• /
• v.18 no.4
• /
• pp.503-514
• /
• 2006

FBG sensors are capable of measuring the strain of structures easily and more durably than electric resistance gauges. Thus, many researches are dedicated to the application for the response monitoring or non-destructive evaluation of structures using FBG sensors. Additionally, the measured strains at the top and bottom of a cross-section can be transformed into the curvature of the section, which can be used to calculate its vertical displacement. Hence, this study aims to measure the dynamic strain signals of a steel section simply supported beam and to estimate the dynamic displacement from the strain signals, after which the estimated displacement is com pared with the measured displacement. The dynamic characteristics (natural frequency, damping ratio and mode shape) of the beam are predicted from both the estimated and measured displacement signals, and from the strain time history of the FBG sensors. The predicted properties are compared with those of an analytical model of the beam. The estimated displacement. However, the predicted dynamic properties from both the estimated displacements and the measured strains are well-correlated with those from the measured displacement. It is therefore appreciated that the estimation of the dynamic properties of FBG sensor signals is reasonable. Especially, the strain signal of the FBG sensor was amplified at a higher-frequency region in comparison with the displacement estimation with higher-mode properties.

• Journal of the Korean Society of Radiology
• /
• v.12 no.4
• /
• pp.443-450
• /
• 2018

The Geant 4 simulated the linear accelerator (VARIAN CLINAC) based on the previously implemented BEAMnrC data, using the head structure of the linear accelerator. In the 10 MV photon flux, Geant4 was compared with the measured value of the percentage of the deep dose and the lateral dose of the water phantom. In order to apply the dose calculation to the body part, the actual patient's lung area was scanned at 5 mm intervals. Geant4 dose distributions were obtained by irradiating 10 MV photons at the irradiation field ($5{\times}5cm^2$) and SAD 100 cm of the water phantom. This result is difficult to measure the dose absorbed in the actual lung of the patient so the doses by the treatment planning system were compared. The deep dose curve measured by water phantom and the deep dose curve calculated by Geant4 were well within ${\pm}3%$ of most depths except the build-up area. However, at the 5 cm and 20 cm sites, 2.95% and 2.87% were somewhat higher in the calculation of the dose using Geant4. These two points were confirmed by the geometry file of Genat4, and it was found that the dose was increased because thoracic spine and sternum were located. In cone beam CT, the dose distribution error of the lungs was similar within 3%. Therefore, if the contour map of the dose can be directly expressed in the DICOM file when calculating the dose using Geant4, the clinical application of Geant4 will be used variously.