• Journal of the Korea Academia-Industrial cooperation Society
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• v.11 no.6
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• pp.2118-2123
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• 2010

Korean individual occupational exposure control is focused on the retrospective service to the over-exposed person by the reading of personal dosimeter. Since the radiophamaceuticals using in the nuclear medicine department are uncontained radiation sources, the potential exposure at working environment is very high. Moreover, a patient remains radioactive for hours or even days after the administration of a radiopharmaceutical for diagnosis or treatment. Thus, the proper working environmental exposure control must be established and executed to protect not only the affiliated employees, but also guardians accompanying patients and temporarily visiting public from the exposure by the patients. Japanese radiation protection law regulates working environmental radiation exposure by regularly measuring and filing the environmental dose for years. This study was aimed at measuring working environmental radiation dose in the nuclear medicine department of an university hospital located in Daejeon, Korea. We measured the accumulation radiation dose in air at 8 locations in the nuclear medicine department by using the same method as in Japan with glass dosimeters. The highest dose rate, 0.23 mSv per month, was measured at the waiting room, and the second one is at reception desk. Even though the doses were lower than the Korean constraint dose rate (0.3 mSv/week) at the boundary of the radiation controlled area, it was over the dose limit of public (1 mSv/y) and environment (0.25 mSv/y). Conclusionally, it was found that the new or additional procedure was necessary to less the exposure dose to the receptionist and guardians by the environmental radiation dose in the nuclear medicine department.

• Journal of the Society of Naval Architects of Korea
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• v.49 no.2
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• pp.158-163
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• 2012

Recently, reducing underwater radiated noise (URN) of ships has become an environmental issue to protect marine wildlife. URN of ships can be predicted by various methods considering its generating mechanism and frequency ranges. For URN prediction due to ship structural vibration in low frequency range, the fluid-structure interaction analysis technique based on finite element and boundary element methods (FE/BEM) is regarded as an useful technique. In this paper, URN due to a double bottom-shaped structure vibration has been numerically investigated based on a coupled method of FE/BEM to enhance the prediction accuracy of URN due to the vibration of real ship engine room structure. Acoustic radiation efficiency and URN transfer function in case of vertical harmonic excitation on the top plate of double bottom structure have been evaluated. Using the results, the validity of an existing empirical formula for acoustic radiation efficiency estimation and a simple URN transfer function, which are usually adopted for URN assessment in initial design stage, is discussed.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.22 no.1
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• pp.22-28
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• 2012

While a dash panel component, close to passengers, plays a very important role to protect heat and noise from a power train, it is also a main path that transfers vibration energy and eventually radiates acoustic noise into the cavity. Therefore, it is important to provide optimal design schemes incorporating sound packages such as a dash isolation pad and a floor carpet, as well as structures. The present study is the extension of the previous investigation how design variables affect sound radiation, which was carried out using the simple plate and framed system. A novel FE-SEA hybrid simulation model is used for this study. The system taken into account is a dash panel component of a sedan vehicle, which includes front pillars, front side members, a dash panel and corresponding sound packages. Design variables such as panel thicknesses and sound packages are investigated how they are related to two main NVH indexes, sound radiation power(i.e. structure-borne) and sound transmission loss(i.e. air borne). In the viewpoint of obtaining better NVH performance, it is shown that these two indexes do not always result in same tendencies of improvement, which suggests that they should be dealt with independently and are also dependent on frequency regions.

• Journal of the Korean Society of Radiology
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• v.14 no.3
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• pp.295-301
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• 2020

Radiation exposure exposed during mammography, which is performed for early examination of breast cancer, has also been suggested as a cause of carcinogenesis in the past, and scattered rays generated during examination may cause unnecessary radiation exposure to surrounding organs. In this study, the Monte Carlo simulation was used to evaluate the human organ doses exposed during conventional mammography, and to estimate the dose reduction effect for each organ when using 3D printing materials for radiation protection by scattered rays. As a result of organ dose evaluation, the breast on the opposite side of the examination was about 22.0% of the breast on the test side and about 58.6% on the eye, which was highly influenced by the scattering-ray. When using the 3D printing shield to protect it, the breast on the opposite side of the test showed an effective dose reduction effect at a thickness of 1 mm.

• The Journal of the Korea Contents Association
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• v.16 no.3
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• pp.661-666
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• 2016

In this study, a linear accelerator (LINAC) through 3 Gy of radiation per body irradiated mice of the small intestine and the liver to produce in order to protect the cells after radiation exposure that caspase (caspase 3 &caspase 9) and NO (nitric oxide), and looked like to know cytokine of IL-6 and TNF-${\alpha}$, the result is as follows. First, caspase 3 & caspase 9 showed a noticeable increase in the radiation group than in the control group both small intestine and liver tissues (P <0.001). Second, NO are both intestine and liver tissue showed a marked increase in the radiation group than in the control group (P <0.001). Third, one of Cytokine IL-6 and TNF-${\alpha}$ showed a significant increase in the irradiated group than the control group both small intestine and liver tissues (P <0.001).

• Nuclear Engineering and Technology
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• v.45 no.1
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• pp.1-12
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• 2013

This paper describes the radiation doses to human and non-human biota in the Republic of Korea, as a result of the Fukushima nuclear accident. By using the measured airborne activity and ground deposition, the effective and thyroid doses of five human age groups (infant, 5 years, 10 years, 15 years and adult) were estimated by the ECOSYS code, and the whole body absorbed dose rate of the eight Korean reference animals and plants (RAPs) was estimated by the K-BIOTA (the Korean computer code to assess the risk of radioactivity to wildlife). The first-year effective and thyroid human doses ranged from 5.7E-5 mSv in the infant group to 2.0E-4 mSv in the 5 years group, and from 5.0E-4 mSv in the infant group to 3.4E-3 mSv in the 5 years group, respectively. The life-time (70 years) effective and thyroid human doses ranged from 1.5E-4 mSv in the infant group to 3.0E-4 mSv in the 5 years group, and from 6.0E-4 mSv in the infant group to 3.5E-3 mSv in the 5 years group, respectively. The estimated maximum whole body absorbed dose rate to the Korean RAPs was 6.7E-7 mGy/d for a snake living in soil (terrestrial biota), and 2.0E-5 mGy/d for freshwater fish (aquatic biota), both of which were far less than the generic dose criteria to protect biota from ionizing radiation. Also, the screening level assessment for ERICA's (Environmental Risks from Ionizing Contaminants: Assessments and management) limiting organisms showed that the risk quotient (RQ) for the estimated maximum soil and water activity was significantly less than unity for both the terrestrial and freshwater organisms. Conclusively, the radiological risk of the radioactivity released into the environment by the Fukushima nuclear accident to the public and the non-human biota in the republic of Korea is considered negligible.

• Radiation Oncology Journal
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• v.37 no.1
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• pp.22-29
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• 2019

Purpose: The aim of this study is to evaluate the efficacy and feasibility of four-field box whole brain radiotherapy (FB-WBRT) with tilting baseplate by comparing bilateral WBRT (B-WBRT). Methods and Materials: Between March 2016 and September 2018, 20 patients with brain metastases underwent WBRT using the four-field box technique. WBRT is performed with a dose of 30 Gy in 10 fractions daily. Two computed tomography simulations per person were performed. One was in the traditional supine position for B-WBRT and the other by applying the tilting acrylic supine baseplate to elevate the head by 40° for FB-WBRT. The B-WBRT used the field-in-field technique, which is the most commonly used method in our institution. The FB-WBRT comprised anterior, posterior, and bilateral beams. A wedge was applied in anterior and posterior fields to compensate for skull convexity. Results: The average of Dmean of both parotid glands was 10.2 Gy (range, 3.8 to 17.8 Gy) in B-WBRT and 5.4 Gy (range, 2.0 to 11.7 Gy) in FB-WBRT (p < 0.05). Compared to B-WBRT, FB-WBRT reduced the mean dose of the right and left parotid glands from 10.1 Gy to 4.9 Gy and from 10.4 Gy to 5.8 Gy, respectively (p < 0.05). Further, V₅, V₁₀, V₁₅, V₂₀, and V₂₅ for the parotid gland decreased significantly in FB-WBRT (p < 0.05). The Dmax and Dmean of lens decreased according to the dose-volume histogram. Conclusion: Compared to B-WBRT, FB-WBRT with a tilting baseplate is a simple and effective method that takes feature of noncoplanar beam to protect the parotid gland.

• Journal of the Institute of Electronics and Information Engineers
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• v.51 no.12
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• pp.174-179
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• 2014

In this study, we measure the radiation dose for every experiments performed during the training education in radiologic science and estimate the radiation dose to each participant in the training education to propose a safe curriculum including operation of the training education. In this paper, we optimized the three parameters and the results show the dramatically reduced radiation dose to each participant. The proposed arrangement of the subjects and operation of the training education will be very helpful to reorganize the curriculum and the subject operation and will protect the students from the radiation dose.

• Journal of Korean Academy of Oral and Maxillofacial Radiology
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• v.9 no.1
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• pp.25-31
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• 1979

The utilization of x-ray for diagnosis and examination is increasing by about 5-15% every year, therefore, it would be mandatory to protect the patients from exposures and so, studies in this field are performed even now. In dental field, the area of irradiation is limited any to the head and neck area, but the irradiated angle is varied following the objected tooth, so the adjacent structures lens and thyroid gland would be fragile to radiation. And the scattered radiation is one of the complicated problems in the protection because of specificity of dental x-ray and its object structures. The author, by using TLD (Thermo luminescent Dosimeter; Teledyne Isotopes-Model 7300, Element; TLD 200(CaF₂:Dy) and Capintec(Capintec Model 192, PM-30 Diagnostic chamber 28㎖ active volume), tried a measurement of air dose distribution of the scattered radiation and the irradiated dose of lens and thyroid gland under the condition of taking the film on the left maxillary molar. The results were as follows: 1. The half value layer of adapted dental x-ray machine was measured, and is 1.44㎜ Al. 2. The time of irradiation on the left maxillary molar in the Alderson Rando Phantom, the measured doses of left and right lens, and thyroid gland were 8,9mR, 1,2mR and 2,8mR. Under the same conditions, the scattered radiation at the distance of 1 meter from the phantom were 84 μR at the front side, 11μR at the back side, 18μR at the right side and 72μR at the left side. 3. Under the same conditions, the dose showed higher value by about 5% in the presence of object(phantom) than in the case of absence.

• Korean Journal of Veterinary Research
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• v.56 no.1
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• pp.29-35
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• 2016

When exposed to gamma-rays, hair follicular cells immediately go through apoptosis, which hampers their rapid differentiation essential for the regeneration of hair. Phloroglucinol (PG) is a phenolic compound of Ecklonia cava, brown algae abundant in Jeju island, Korea. Containing plentiful polyphenols, PG is known for its instructive effects by inhibiting apoptosis, scavenging oxygen radicals, and protecting cells against oxidative stress. In this study, we demonstrate that PG rescues radiosensitive hair follicular cells from gamma radiation-induced apoptosis and DNA damage. To identify protective capacity of PG on hair follicles, we irradiated with 8.5 Gy (1.5 Gy/min) of gamma-rays to the whole body of C57BL/6 mice at day 6 after depilation with or without PG. In mice exposed to radiation, the expression of proapoptotic molecule p53 was downregulated in the skin of PG treated group. On immunohistochemical observation of the skin, PG inhibited the immunoreactivity of p53 and cleaved caspase-3. PG treatment protected hair follicular cells from cell death due to gamma-radiation. Our results suggest that PG presents radioprotective effects by inhibiting apoptosis of radiosensitive hair follicular cells and can protect hair follicular cells from gamma-ray induced damage.