• Journal of the Korean Society of Radiology
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• v.17 no.3
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• pp.449-457
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• 2023

Shielding for reducing exposure dose can make the diagnosis limited. The purpose of this study is to increase the efficiency of radiation protection and minimize the loss of image information by producing the shielding made of the water and the contrast medium which has different proportion and finding out the ideal proportion of them. Each shielding materials were made of water and water-soluble iodine contrast medium with the different proportion. The attenuation rate of absorbed dose was evaluated by the shielding materials in the plastic contents for measuring the efficiency of the radiation protection. As a result, the higher ratio of the contrast medium, the more efficient it is for radiation attenuation. The anatomical structure was observed most properly in case of the solution with 20 ml of the contrast medium and most difficultly in case of more than 60 ml of the contrast medium. In case of the signal intensity between skeleton and gas, the difference of average value had a significant as p < 0.001. Shielding with contrast medium attenuates less than the conventional shielding but in the examination for the sensitive part to radiation, it can be used to minimize the loss of the image information and reduce the exposure dose.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.29 no.9 s.240
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• pp.988-996
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• 2005

Flame structure and extinction mechanism of counterflow methane/air non-premixed flame diluted with nitrogen are studied by NASA 2.2 s drop tower experiments and two-dimensional numerical simulations with finite rate chemistry and transport properties. Extinction mechanism at low strain rate is examined through the comparison among results of microgravity experiment, 1D and 2D simulations with a finite burner diameter. A two-dimensional simulation in counterflow flame especially with a finite burner diameter is shown to be very important in explaining the importance of multidimensional effects and lateral heat loss in flame extinction, effects that cannot be understood using a one-dimensional flamelet model. Extinction mechanism at low strain rate is quite different from that at high strain rate. Low strain rate flame is extinguished initially at the outer flame edge, the flame shrinks inward, and finally is extinguished at the center. It is clarified from the overall fractional contribution by each term in energy equation to heat release rate that the contribution of radiation fraction with 1D and 2D simulations does not change so much and the overall fractional contribution is decisively attributed to radial conduction ('lateral heat loss'). The experiments by Maruta et at. can be only completely understood if multi-dimensional heat loss effects are considered. It is, as a result, verified that the turning point, which is caused only by pure radiation heat loss, has to be shifted towards much lower global strain rate in microgravity flame.

• Proceedings of the Korean Society of Toxicology Conference
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• 2002.05a
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• pp.83-83
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• 2002

To assess the role of 8-oxoguanine glycosylase (OGG1) in the cell defense against radiation injury, the radiation-induced cytotoxicities were compared between the mutant type KG-1 featuring a loss of OGG1 activity due to a homozygous mutation of Arg 229 G1n, and the wild type U937.(omitted)

• International Journal of Naval Architecture and Ocean Engineering
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• v.6 no.4
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• pp.894-903
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• 2014

Insertion loss prediction of large acoustical enclosures using Statistical Energy Analysis (SEA) method is presented. The SEA model consists of three elements: sound field inside the enclosure, vibration energy of the enclosure panel, and sound field outside the enclosure. It is assumed that the space surrounding the enclosure is sufficiently large so that there is no energy flow from the outside to the wall panel or to air cavity inside the enclosure. The comparison of the predicted insertion loss to the measured data for typical large acoustical enclosures shows good agreements. It is found that if the critical frequency of the wall panel falls above the frequency region of interest, insertion loss is dominated by the sound transmission loss of the wall panel and averaged sound absorption coefficient inside the enclosure. However, if the critical frequency of the wall panel falls into the frequency region of interest, acoustic power from the sound radiation by the wall panel must be added to the acoustic power from transmission through the panel.

• Proceedings of the SAREK Conference
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• 2008.06a
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• pp.919-924
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• 2008

Power consumption in the building thermal load could be the sum of the building fabric conduction load, building ventilation convection load and other such as radiation loss load. Dynamic Breathing Building (DBB) is the state-of-the-art to improve the wall insulation and indoor air quality(IAQ) performance as making air flow through the wall. This heat recovery type DBB contributes the power consumption saving due to the improved dynamic U-value. KIER twin test cell with static insulation(SI) and dynamic insulation(DI) at KIER was developed to test building power consumption at the real outside conditions. Then, the actual results were compared with the theory to predict the power consumption at the KIER twin test cell and introduced the building new radiation loss factor $\alpha$ to explain the difference between the both the theory and the actual case. As the results, the power consumption at the breathing DI wall building could saved 10.8% at the 2ACH(Air change per hour) compared with conventional insulation. The building radiation loss factor $\alpha$ for this test condition to calibrate the actual test was 0.55 in the test condition.

• Nuclear Engineering and Technology
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• v.56 no.2
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• pp.715-727
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• 2024

During fast neutron imaging, besides the dark current noise and readout noise of the CCD camera, the main noise in fast neutron imaging comes from high-energy gamma rays generated by neutron nuclear reactions in and around the experimental setup. These high-energy gamma rays result in the presence of high-density gamma white spots (GWS) in the fast neutron image. Due to the microscopic quantum characteristics of the neutron beam itself and environmental scattering effects, fast neutron images typically exhibit a mixture of Gaussian noise. Existing denoising methods in neutron images are difficult to handle when dealing with a mixture of GWS and Gaussian noise. Herein we put forward a deep learning approach based on the Swin Transformer UNet (SUNet) model to remove high-density GWS-Gaussian mixture noise from fast neutron images. The improved denoising model utilizes a customized loss function for training, which combines perceptual loss and mean squared error loss to avoid grid-like artifacts caused by using a single perceptual loss. To address the high cost of acquiring real fast neutron images, this study introduces Monte Carlo method to simulate noise data with GWS characteristics by computing the interaction between gamma rays and sensors based on the principle of GWS generation. Ultimately, the experimental scenarios involving simulated neutron noise images and real fast neutron images demonstrate that the proposed method not only improves the quality and signal-to-noise ratio of fast neutron images but also preserves the details of the original images during denoising.

• Journal of Radiation Industry
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• v.17 no.1
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• pp.75-82
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• 2023

This research was carried out to evaluate on microbiological (total aerobic bacteria, yeast and mold) and physicochemical (color, firmness, water content, water activity and weight loss) characteristics of 10MeV electron-beam irradiated(0, 0.5, 1, 2 and 3kGy) enoki mushroom during storage (0, 7, 14, 21 and 28 day) at 4℃ with 80% relative humidity. As compared to control, all irradiated samples exhibited dose-dependent decreases of microbial counts up to 28 days, and electron beam irradiation above 2 kGy kept below the microbiological safety threshold. Yellowness (b^*) which is associated with discoloration of mushrooms was significantly reduced by electron beam irradiation (2 kGy). Firmness, water content, water activity and weight loss showed no significant difference in all group up to 28 days. Thus, the appropriate electron-beam irradiation dose was confirmed as 2 kGy to inhibit the microbial growth and browning reaction in enoki mushroom.

• Radiation Oncology Journal
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• v.38 no.2
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• pp.84-92
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• 2020

Patients undergoing radiation therapy for head and neck cancer (HNC) experience significant early and long-term side effects. The likelihood and severity of complications depends on a number of factors, including the total dose of radiation delivered, over what time it was delivered and what parts of the head and neck received radiation. Late side effects include: permanent loss of saliva; osteoradionecrosis; radiation recall myositis, pharyngoesophageal stenosis; dental caries; oral cavity necrosis; fibrosis; impaired wound healing; skin changes and skin cancer; lymphedema; hypothyroidism, hyperparathyroidism, lightheadedness, dizziness and headaches; secondary cancer; and eye, ear, neurological and neck structures damage. Patients who undergo radiotherapy for nasopharyngeal carcinoma tend to suffer from chronic sinusitis. These side effects present difficult challenges to the patients and their caregivers and require life-long strategies to alleviate their deleterious effect on basic life functions and on the quality of life. This review presents these side effects and their management.

• Korean Journal of Head & Neck Oncology
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• v.24 no.2
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• pp.184-188
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• 2008

Objectives：Weight loss and malnutrition in patients undergoing radiotherapy for head and neck cancer are usual and preventable. The effect of nutritional support with oral high protein liquid was evaluated. Material and Methods：From Feb. to Dec. 2007, twenty patients received nutritional supplement with oral high protein liquid during radiotherapy for head and neck cancer and the nutritional status was evaluated. Weight loss was compared with control group of similar clinical characteristics. Results：Nutritional parameters such as weight, arm circumference, hemoglobin, hematocrit, total protein, albumin, transferring and the number of lymphocyte were relatively well maintained in patients with nutritional support with oral high protein liquid. In addition weight loss was minimal and significantly lower compared with control group. Conclusion：Nutritional support with oral high protein liquid was effective on maintaining nutritional status for the patients with head and neck cancer during radiotherapy.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.25 no.1
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• pp.29-35
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• 2001

Radiation-induced oscillatory instability in CH$_4$/Air diffusion flames is numerically investigated by adopting detailed chemistry. Counterflow diffusion flame is employed as a model flamelet and optically thin gas-phase radiation is assumed. Attention is focused on the extinction regime induced by radiative heat loss, which occurs at low strain rate. Once a steady flame structure is obtained for a prescribed value of initial strain rate, transient solution of the flame is calculated after a finite amount of strain-rate perturbation is imposed on the steady flame. Depending on the initial strain rate and the amount of perturbed strain rate, transient evolution of the flame exhibits various types of flame-evolution behaviors. Basically, the dynamic behaviors can be classified into two types, namely oscillatory decaying solution and diverging solution leading to extinction.