• Journal of the Korean Society for Geothermal and Hydrothermal Energy
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• v.18 no.3
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• pp.7-18
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• 2022

Secondary batteries used in electric vehicles have a potential risk of ignition and explosion. Various safety measures are being taken to prevent these risks. A numerical study was performed using a computational fluid dynamics code on the cases where pressure relief vents that can reduce the blast overpressures of batteries were installed in the through-compression test room, short-circuit drop test room, combustion test room, and immersion test room in facilities rleated to battery used in electric vehicles. This study was conducted using the weight of TNT equivalent to the energy release from the battery, where the the thermal runaway energy was set to 324,000 kJ for the capacity of the lithium-ion battery was 90 kWh and the state of charge (SOC) of the battery of 100%. The explosion energy of TNT (△H_TNT) generally has a range of 4,437 to 4,765 kJ/kg, and a value of 4,500 kJ/kg was thus used in this study. The dimensionless explosion efficiency coefficient was defined as 15% assuming the most unfavorable condition, and the TNT equivalent mass was calculated to be 11 kg. The internal explosion generated in a test room shows the very complex propagation behavior of blast waves. The shock wave generated after the explosion creates reflected shock waves on all inner surfaces. If the internally reflected shock waves are not effectively released to the outside, the overpressures inside are increased or maintained due to the continuous reflection and superposition from the inside for a long time. Blast simulations for internal explosion targeting four test rooms with pressure relief vents installed were herein conducted. It was found that that the maximum blast overpressure of 34.69 bar occurred on the rear wall of the immersion test room, and the smallest blast overpressure was calculated to be 3.58 bar on the side wall of the short-circuit drop test room.

• Journal of the Korean Society of Marine Environment & Safety
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• v.22 no.6
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• pp.758-765
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• 2016

In this study, wave damping due to a permeable bed of finite depth was modelled using a complementary mild-slope equation for stream function. The energy dissipating term in the mild-slope equation was presented in terms of stream function. In order to prevent re-reflection of reflected waves along the outer boundary, a delta-function-shaped source function was derived to generate a wave in a computational domain. Numerical experiments were conducted to measure the reflection coefficient of waves over a planar slope for various incident wave periods. The numerical result of the proposed model was compared with that of an integral equation method, showing good agreement in general. However, the proposed model showed relatively higher transmission rate for the larger permeability and the longer wavelength.

• Journal of the Korean Society for Nondestructive Testing
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• v.28 no.1
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• pp.46-53
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• 2008

Ultrasonic C-scan technique is one of very popular techniques being used for detection of flaws in polymer matrix composite(PMC). However, the application of this technique is very limited for evaluation of defects in PMC fabricated by the automated fiber placement process. The purpose of this study is to develop a novel ultrasonic hybrid system based on nondestructive and non-contact ultrasonic techniques for evaluation of delamination in carbon/epoxy and carbon/PPS composite laminates. It was shown that the newly developed ultrasonic hybrid system based on dual air-coupled pitch-catch technique with ultrasonic scattering reflection concept could provide excellent image with higher resolution of delamination in PMC compared with the conventional pitch-catch method. It is expected that this ultrasonic hybrid technique can be applied for on-line inspection of flaws in PMC during the fabrication process.

• Journal of Veterinary Clinics
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• v.22 no.4
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• pp.408-411
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• 2005

Schistosomus reflexus is the most common monstrosity found in cases of bovine dystocia and it occurs mostly in cattle. Caesarian section performed and retracted abnormal foetus from dystocia in Holstein cow. It was the first observed schistosomus reflexus Holstein calf in Korea. The body and chest walls were bent laterally and dorsally leaving the thoracic and abdominal viscera exposed. Clefts of the sternum from part of the defect in which there is, simultaneously, lordosis, dorsal reflection of the ribs and complete eventration of viscera, severe ventral curvature of the spinal column, non-union of the pelvic symphysis and dorsal reflection of the pelvic bones with the occiput of the head lying near the sacrum. The limbs are usually ankylosed. The liver was abnormal in shape and cystic in nature. The lung was smaller and thymus were bigger than those of the normal calf, The ruminant stomach was normal, however, abomasum distended with amnionic fluid. The other organ including heart, spleen and internal organ have normal shape.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.10
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• pp.540-548
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• 2018

The purpose of this study was to test the validity and reliability of the Satisfaction with Simulation Experience (SSE) scale for evaluating high-fidelity simulation education for nursing students. Participants were 174 nursing students, seniors enrolled in two colleges in two different regions. Collected data were analyzed using SPSS / WIN 22.0 and tested for construct validity (factor analysis, group comparison test) and reliability (internal consistency). Factor analysis revealed 17 items and 3 factors explaining 71.581% of the variance. Group comparisons showed that satisfaction with simulation training differed significantly across satisfaction to a college life and school record. Internal consistency reliability for all items was .945. For each sub-domain, the reliability coefficient was .929 for 'Debrief', .908 for 'Clinical learning and reflection', and .860 for 'Clinical reasoning'. Nursing students' mean satisfaction with simulation using the high-fidelity simulator was 3.92. Results of this study are expected to be used for evaluating the satisfaction of nursing college students receiving high-fidelity simulation education, and to serve as groundwork for the development and application of nursing simulation education.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.48 no.3
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• pp.1-12
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• 2011

Large-sized multi-touch screen is usually made using infrared rays. That is because it has technical constraints or cost problems to make the screen with the other ways using such as existing resistive overlays, capacitive overlay, or acoustic wave. Using infrared rays to make multi-touch screen is easy, but is likely to have technical limits to be implemented. To make up for these technical problems, two other methods were suggested through Surface project, which is a next generation user-interface concept of Microsoft. One is Frustrated Total Internal Reflection (FTIR) which uses infrared cameras, the other is Diffuse Illumination (DI). FTIR and DI are easy to be implemented in large screens and are not influenced by the number of touch points. Although FTIR method has an advantage in detecting touch-points, it also has lots of disadvantages such as screen size limit, quality of the materials, the module for infrared LED arrays, and high consuming power. On the other hand, DI method has difficulty in detecting touch-points because of it's structural problems but makes it possible to solve the problem of FTIR. In this thesis, we study the algorithms for effectively correcting the distort phenomenon of optical lens, and image processing algorithms in order to solve the touch detecting problem of the original DI method. Moreover, we suggest calibration algorithms for improving the accuracy of multi-touch, and a new tracking technique for accurate movement and gesture of the touch device. To verify our approaches, we implemented a table-based multi touch screen.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.24 no.1
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• pp.98-105
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• 2013

This paper presents a finite-difference time-domain(FDTD) simulation and a data processing technique for radar sensing of the internal structure of a wall using an ultra-wide band antenna. We first designed an ultra-wide band anti-podal vivaldi antenna with a frequency range of 0.3~7 GHz which is chosen to be relatively low after considering the characteristics of wave attenuation, wall penetration, and range resolution. In this study the two-dimensional FDTD technique was used to simulate a wall-penetration-radar experiment under practical conditions. The next, the measured radiation pattern of the practical antenna is considered as an equivalent source in the FDTD simulation, and the reflection data of a concrete wall and targets are obtained by using the simulation. Then, a data processing technique has been applied to the FDTD reflection data to get a radar image for remote sensing of the internal structure of the wall. We compared the two different source excitations in the FDTD simulation; (1) commonly-used isotropic point sources and (2) polynomial curve fitting sources of the measured radiation pattern. As a result, when we apply the measured antenna pattern into the FDTD simulation, we could obtain about 2.5 dB higher signal to noise level than using a plane wave incidence with isotropic sources.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.28 no.3B
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• pp.323-334
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• 2008

Present study examined the functionality of the solitary wave (tsunami) control of the two-rowed porous submerged breakwater by numerical experiments, using a numerical wave tank which is based on the Navier-Stokes equation to explain fluid fields and uses a Volume of Fluid (VOF) method to capture the free water surface. Solitary wave was generated by the internal wave source installed within the computational zone in the numerical wave tank and its wave transformations by structure were compared with those in the previous study. Comparisons with the precious numerical results showed a good agreement. Based on these results, several tow-dimensional numerical modeling investigations of the water fields, including wave transformations, reflection, transmission and energy flux, by the one- and two-rowed permeable submerged breakwater under solitary waves were performed. Even if, it is a research of the limited scope, in case of two-rowed permeable submerged breakwater with $h_0/h=0.925$ ($h_0$ is height of submerged breakwater and h is water depth), the wave height damping in range of $l/L_{eff}>0.4$($L_{eff}$ is effective distance of solitary wave) can reach nearly 60% of the incident wave height. In addition, it is found that reflection coefficient increases nearly 47% and transmission coefficient decreases nearly 18% than one-rowed one. The numerical results revealed that the tow-rowed submerged breakwater can control the incident solitary wave economically and more efficiently than the one-rowed one.

• Korean Journal of Psychosomatic Medicine
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• v.25 no.1
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• pp.56-62
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• 2017

Objectives : The objective of this study was to investigate the relationship between psychological distress and pain in cancer patients. Methods : 249 patients with cancer who visited National Health Insurance Service Ilsan Hospital between April 2013 and March 2014 were evaluated with National Cancer Center Psychological Symptom Inventory(NCC-PSI) which consisted of Modified Distress Thermometer(MDT) and Modified Impact Thermometer(MIT). Each scale was divided into 3 subscales targeting separate symptoms: insomnia, anxiety, and depression. Psychological distress was defined as positive for those who scored above the cutoff values in at least one of all six subscales. The Numeric Rating Scale for Pain(NRS-Pain) was used to assess the subjective severity of pain. Logistic regression was performed to investigate the association between psychological distress and pain. Results : Univariate logistic regression analysis showed that pain, gender, compliance, and two subscale scores of Hospital Anxiety and Depression Scale(HADS) were significantly associated with psychological distress. Multivariate logistic regression analysis showed that pain and HADS anxiety subscale score maintained a statistically significant association with psychological distress adjusted for variables including age, gender, years of education, Eastern Cooperative Oncology Group performance status, cancer stage, Charlson Comorbidity Index, compliance, and HADS depression subscale score. One point increase in pain was 1.31 times more likely to cause psychological distress. In secondary analysis, pain was significantly associated with all subscales of NCC-PSI, except MIT-anxiety subscale. Conclusions : This study suggests that NCC-PSI, a screening tool for psychological distress, reflects pain. We recommend that physicians who treat cancer patients consider the examination of psychological distress which provides comprehensive evaluation of various factors regarding quality of life.

• Journal of Digital Contents Society
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• v.18 no.7
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• pp.1457-1464
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• 2017

This paper is to introduce the a system which monitors and detects the object position in reinforced the concrete structure using UWB-RF. This system is able to check any changes in the inside of the concrete structure using its penetration and reflection characteristics and it can also numerically measure the position of rebar in the concrete structure. For the verification of the performance of this system, we set up the internal compositions of concrete in 3 different types of test-bed. On the other hand, for the measuring of the location of rebar, which varies depending on the type of structure, the software which shows the distance in the structure were used. The result shows that the position in the concrete could be measured within the tolerance of ${\pm}1{\sim}4mm$ depending on the type of structure in the concrete.