• Journal of Environmental Health Sciences
• /
• v.37 no.3
• /
• pp.226-233
• /
• 2011

Exactly 25 years after the Chernobyl nuclear disaster, 11th of March 2011 the Fukushima nuclear accident occurred in Japan and was ranked at level 7 same to the Chernobyl. A Korean and Japanese joint civil survey was conducted around Fukushima on April 13-17. The radiation survey data clearly shows a large hotspot area between 20 km and 50 km radius north and west direction from the accident reactors, with the highest radiation recorded being 55.64 ${\mu}Sv/hr$ in the air, 99.89 ${\mu}Sv/hr$ in the surface air, and 36.16 ${\mu}Sv/hr$ in a car, respectively. 3.65 ${\mu}Sv/hr$ in the air and 6.89 ${\mu}Sv/hr$ in the surface air were detected at the playground of an elementary school in Fukushima City. Spring came with full cherry blossoms in Fukushima, but it was silent spring of radiation contamination. Interviews with Fukushima nuclear refugees reveal serious problems about Japanese nuclear safety systems, such as there was no practical evacuation drill within 1-10 km and no plan at all for 10-30 km areas. Several reforms items for Korean nuclear safety system can be suggested: minimization of accident damage, clear separation of regulatory and safety bureaus with a new and independent administrating agency, community participation and agreement regarding the safety system and levels, which is the major concern of 80% Korean. To tackle threats of nuclear disaster in neighboring nations like China, a new position entitled 'Ambassador for nuclear safety diplomacy' is highly necessary. The nuclear safety of Korea should no longer be the monopoly of those nuclear engineers and limited technocrats criticized as a 'nuclear mafia'.

• Journal of radiological science and technology
• /
• v.39 no.4
• /
• pp.509-516
• /
• 2016

A dental panoramic radiography which usually uses low level X-rays is subject to the Nuclear Safety Act when it is installed for the purpose of education. This paper measures radiation dose and spatial dose rate by usage and thereby aims to verify the effectiveness of radiation safety equipment and provide basic information for radiation safety of radiation workers and students. After glass dosimeter (GD-352M) is attached to direct exposure area, the teeth, and indirect exposure area, the eye lens and the thyroid, on the dental radiography head phantom, these exposure areas are measured. Then, after dividing the horizontal into a $45^{\circ}$, it is separated into seven directions which all includes 30, 60, 90, 120 cm distance. The paper shows that the spatial dose rate is the highest at 30 cm and declines as the distance increases. At 30 cm, the spatial dose rate around the starting area of rotation is $3,840{\mu}Sv/h$, which is four times higher than the lowest level $778{\mu}Sv/h$. Furthermore, the spatial dose rate was $408{\mu}Sv/h$ on average at the distance of 60 cm where radiation workers can be located. From a conservative point of view, It is possible to avoid needless exposure to radiation for the purpose of education. However, in case that an unintended exposure to radiation happens within a radiation controlled area, it is still necessary to educate radiation safety. But according to the current Medical Service Act, in medical institutions, even if they are not installed, the equipment such as interlock are obliged by the Nuclear Safety Law, considering that the spatial dose rate of the educational dental panoramic radiography room is low. It seems to be excessive regulation.

• Journal of Radiation Protection and Research
• /
• v.33 no.4
• /
• pp.151-160
• /
• 2008

In Korean nuclear power plants (NPPs), two thermoluminescent dosimeters (TLD) were provided to workers who work in an inhomogeneous radiation field; one on the chest and the other on the head. In this way, the effective dose for radiation workers at NPPs was determined by the high deep dose between two radiation dose from these TLDs. This represented a conservative method of evaluating the degree of exposure to radiation. In this study, to prevent the overestimation of the effective dose, field application experiments were implemented using two-dosimeter algorithms developed by several international institutes for the selection of an optimal algorithm. The algorithms used by the Canadian Ontario Power Generation (OPG) and American ANSI HPS N13.41, NCRP (55/50), NCRP (70/30), EPRI (NRC), Lakslumanan, and Kim (Texas A&M University) were extensively analyzed as two-dosimeter algorithms. In particular, three additional TLDs were provided to radiation workers who wore them on the head, chest, and back during maintenance periods, and the measured value were analyzed. The results found no significant differences among the calculated effective doses, apart from Lakshmanan's algorithm. Thus, this paper recommends the NCRP(55/50) algorithm as an optimal two-dosimeter algorithm in consideration of the solid technical background of NCRP and the convenience of radiation works. In addition, it was determined that a two-dosimeter is provided to a single task which is expected to produce a dose rate of more than 1 mSv/hr, a difference of dose rates depending on specific parts of the body of more than 30%, and an exposure dose of more than 2 mSv.

• Radiation Oncology Journal
• /
• v.18 no.3
• /
• pp.182-186
• /
• 2000

Purpose : To determine treatment or이ecol for inoperable esophageal cancer patients, 껜e evaluated survival rate and prognostic factors. Materials and Methods : We evaluated esophageal cancer treated by curative or palliative am in KCCH from 1992 to 1996, retrospectively. Recurrent or underdose case below 40 Gy were excluded. The number of male and female were 35 and 5, respectively. Thirty-eight patients were squamous carcinoma and 2 patients were not biopsy proven. Ten patients were treated with radiation therapy and chemotherapy Median dose of radiation therapy was 59.4 Gy and the range was $40\~60$ Gy. Results : The median survival is 6.5 months and 1-year survival rate was $28.3\%$. Age, location, radiation dose and chemotherapy were not significant prognostic factors. Median survivals of patients with below stage III and over stage IVA were 7.6 and 6.2 months respectively, but it is not significant. Conclusions : The survival for esophageal cancer is very poor. For patients with curative aim, chemotherapy must be considered. For patients with palliative aim, short-term external beam radiation therapy and/or brachytherapy must be considered.

• Journal of the Korean Society of Radiology
• /
• v.11 no.2
• /
• pp.139-144
• /
• 2017

Percutaneous vertebroplasty (PVP) is increasingly used to treat osteoporotic vertebral fractures, myeloma and osteolytic vertebral metastases. The purpose of this study was to measure the absorbed radiation exposure dose and time during PVP and to assess the possibility of deterministic radiation effects to the operator and patient. The radiation dose and time measure by three pain physicians performed consecutive procedures using the twenty case PVP. Patient's dosimeter placed at the anteroposterior(AP) side was treatment of the vertebra body located in the upper level 2-3 and lateral(LAT) side was flank proximal to C-arm tube of back. Operator's dosimeter placed at the apron outside of upper sternum (thyroid), left chest, lower extremity and apron inside of left chest. Results: Radiation exposure times were $3.6{\pm}0.71min$. Measurements on the Patient radiation dose were AP $121.4{\pm}48.1{\mu}Sv$, LAT side $614.7{\pm}177.1{\mu}Sv$. Operator radiation dose were outside of the lead apron upper sternum $33.7{\pm}7.3{\mu}Sv$, outside of the lead apron chest $49.2{\pm}15.0{\mu}Sv$, outside of the lead apron lower extremity $12.8{\pm}3.8{\mu}Sv$ and inside of the lead apron chest $4.2{\pm}1.4{\mu}Sv$. To escape from the danger of radiation first long distance from the c-arm tube second exposure time reduced second lead apron used fluoroscopy during PVP is more safety patient and operation from the radiation exposure.

• Journal of the Korean Society of Radiology
• /
• v.13 no.4
• /
• pp.653-659
• /
• 2019

The purpose of this study is to measure the (air dose rate of radiation dose) the discharged patient who was administrated high dose $^{131}I$ treatment, and to predict exposure radiation dose in public person. The dosimetric evaluation was performed according to the distance and angle using three copper rings in 30 patients who were treated with over 200mCi high dose Iodine therapy. The two observer were measured using a GM surverymeter with 8 point azimuth angle and three difference distance 50, 100, 150cm for precise radion dose measurement. We set up three predictive simulations to calculate the exposure dose based on this data. The most highest radiation dose rate was showed measuring angle $0^{\circ}$ at the height of 1m. The each distance average dose rate was used the azimuth angle average value of radiation dose rate. The maximum values of the external radiation dose rate depending on the distance were $214{\pm}16.5$, $59{\pm}9.1$ and $38{\pm}5.8{\mu}Sv/h$ at 50, 100, 150cm, respectively. If high dose Iodine treatment patient moves 5 hours using public transportation, an unspecified person in a side seat at 50cm is exposed 1.14 mSv radiation dose. A person who cares for 4days at a distance of 1 meter from a patient wearing a urine bag receives a maximum radiation dose of 6.5mSv. The maximum dose of radiation that a guardian can receive is 1.08mSv at a distance of 1.5m for 7days. The annual radiation dose limit is exceeded in a short time when applied the our developed radiation dose predictive modeling on the general public person who was around the patients with Iodine therapy. This study can be helpful in suggesting a reasonable guideline of the general public person protection system after discharge of high dose Iodine administered patients.

• Journal of Korean Society of Water and Wastewater
• /
• v.35 no.2
• /
• pp.153-162
• /
• 2021

The effects of activated carbon originated Ballasted Flocculant (BF) on the settleability of activated sludge and the recovery of BF by Hydro-cyclone (HC) were analyzed experimentally. Two kinds of BF (M-I: 125-250 ㎛, M-II: 250-425 ㎛ in dia.) and three kinds of activated sludges with different SS concentration (2,300-7,100 mg/L) were applied for this study. With the dosage variation of BF from 0.14 to 1.3 g-BF/g-SS, we could obtain 24-31% improvement in SV30 (Sludge Volume after 30min sedimentation) for the lowest SS concentration sludge (2,300 mg/L). Whereas the SV30 improvement was much higher as 44-48% for the highest SS concentration sludge (7,100 mg/L). The settling characteristics of the sludge with BF followed Vesilind model the best among three models (Vesilind, Takacs and Cho model). HC could effectively separate BF with the separation efficiency of 70-90% and over 95% separation efficiency could be obtained when the HC was applied twice.

• Geophysics and Geophysical Exploration
• /
• v.22 no.1
• /
• pp.21-28
• /
• 2019

We perform a 3D tomographic inversion using surface wave dispersion curves to obtain S-velocity model and radial anisotropy beneath Saudi Arabia. The Arabian Peninsula is geologically and topographically divided into a shield and a platform. We used event data with magnitudes larger than 5.5 and epicentral distances shorter than $40^{\circ}$ during 2008 ~ 2014 from the Saudi Geological Survey. We obtained dispersion curves by using the multiple filtering technique after preprocessing the event data. We constructed SH- and SV-velocity models and consequently radial anisotropy model at 10 ~ 60 km depths by inverting Love and Rayleigh group velocity dispersion curves with period ranges of 5 ~ 140 s, respectively. We observe high-velocity anomalies beneath the Arabian shield at 10 ~ 30 km depths and low-velocity anomalies beneath the Arabian platform at 10 km depth in the SV-velocity model. This discrepancy may be caused by the difference between the Arabian shield and the Arabian platform, that is, the Arabian shield was formed in Proterozoic thereby old and cold, while the Arabian platform is covered by predominant Paleozoic, Mesozoic, and Cenozoic sedimentary layers. Also we obtained radial anisotropy by estimating the differences between SH- and SV-velocity models. Positive anisotropy is observed, which may be generated by lateral tension due to the slab pull of subducting slabs along the Zagros belt.

• Journal of Astronomy and Space Sciences
• /
• v.31 no.1
• /
• pp.33-39
• /
• 2014

This paper describes an experimental approach to evaluate the effective doses of space radiations at high-altitude by combining the measured data from the Liulin-6K spectrometer loaded onto the air-borne RC-800 cockpit and the calculated data from CARI-6M code developed by FAA. In this paper, 15 exposed dose experiments for the flight missions at a high-altitude above 10 km and 3 experiments at a normal altitude below 4 km were executed over the Korean Peninsula in 2012. The results from the high-altitude flight measurements show a dramatic change in the exposed doses as the altitude increases. The effective dose levels (an average of $15.27{\mu}Sv$) of aircrew at the high-altitude are an order of magnitude larger than those (an average of $0.30{\mu}Sv$) of the normal altitude flight. The comparison was made between the measure dose levels and the calculated dose levels and those were similar each other. It indicates that the annual dose levels of the aircrew boarding RC-800 could be above 1 mSv. These results suggest that a proper procedure to manage the exposed dose of aircrew is required for ROK Air Force.

• Journal of Microbiology and Biotechnology
• /
• v.13 no.1
• /
• pp.70-76
• /
• 2003

The benzene removal characteritics of the polyurethane (PU) biofilter immobilized with S. maltophilia T3-c, that could efficiently degrade benzene, was investigated. Maximum capacity to eliminate benzene was maintained at $100-110g{\cdot}m^-3{\cdot}h^-1$ when space velocity (SV) ranged from 100 to $300 h^-1$ -1/, however, it decreased sharply to $55 g{\cdot}m^-3{\cdot}h^-1^$ as SV increased to $400 h^-1$. The critical elimination capacities that guaranteed $90\%$ removal of inlet loading of the PU biofilter were determined to be 70,30, and $15 g{\cdot}m^-3{\cdot}h^-1$ at SV 100,200, and $300 h^-1$, respectively. Based on the result of a kinetic analysis of the PU biofilter, maximum benzene elimination velocity ($V_m$) was $125 g{\cdot}m^-3^\;of\;PU{\cdot}h^-1$ and saturation constant ($K_m$) was $0.22 g{\cdot}m^-3^$ of benzene ($65{\mu}{\cdot}I^-1$). This study suggests that the biofilter utilizing S. maltophilia T3-c and polyurethane is a very promising technology for effectively degrading benzene.