• 제목/요약/키워드: Metal Surface

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Inhibitory Effect of Metal Surface on the Antimicrobial Resistance Microorganism (금속표면이 항생제 내성균주의 생육억제에 미치는 영향)

  • Kim, Jung-Beom;Kim, Jae-Kwang;Kim, Hyunjung;Cho, Eun Jung;Park, Yeon-Joon;Lee, Hae Kyung
    • Annals of Clinical Microbiology
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    • 제21권4호
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    • pp.80-85
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    • 2018
  • Background: The aim of this study was to comparatively evaluate the bactericidal effects of copper, brass (copper 78%, tin 22%), and stainless steel against methicillin-resistant Staphylococcus aureus (MRSA), vancomycin-resistant Enterococcus faecium (VREFM), and multidrug-resistant Pseudomonas aeruginosa (MRPA). Methods: The isolates (MRSA, VREFM, MRPA) used in this study were mixed wild type 3 strains isolated from patients treated at Uijeongbu St. Mary's Hospital in 2017. These strains showed patterns of multidrug resistance. The lyophilized strains were inoculated into and incubated for 24 hr in tryptic soy broth at $35^{\circ}C$. The initial bacterial inoculum concentration was adjusted to $10^5CFU/mL$. A 100-mL bacterial suspension was incubated in containers made of brass (copper 78%, tin 22%), copper (above 99% purity), and stainless steel at $35^{\circ}C$. Viable counts of bacteria strains were measured for 9 days. Results: In this study, the bactericidal effects of copper and brass on MRSA, VREFM, and MRPA were verified. The bactericidal effect of stainless steel was much weaker than those of copper and brass. The bactericidal effect was stronger on MRPA than on MRSA or VREFM. Conclusion: To prevent cross infection of multidrug resistant bacteria in hospitals, further studies of longer duration are needed for testing of copper materials on objects such as door knobs, faucets, and bed rails.

Decomposition of Eco-friendly Liquid Propellants over Platinum/Hexaaluminate Pellet Catalysts (백금/헥사알루미네이트 펠렛 촉매를 이용한 친환경 액체 추진제 분해)

  • Jo, Hyeonmin;You, Dalsan;Kim, Munjeong;Woo, Jaegyu;Jung, Kyeong Youl;Jo, Young Min;Jeon, Jong-Ki
    • Clean Technology
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    • 제24권4호
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    • pp.371-379
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    • 2018
  • The objective of this study is to develop a platinum/hexaaluminate pellet catalyst for the decomposition of eco-friendly liquid propellant. Pellet catalysts using hexaaluminate prepared by ultrasonic spray pyrolysis as a support and platinum as an active metal were prepared by two methods. In the case of the pellet catalyst formed by loading the platinum precursor onto the hexaaluminate powder and then adding the binder (M1 method catalyst), the mesopores were well developed in the catalyst after calcination at $550^{\circ}C$. However, when this catalyst was calcined at $1,200^{\circ}C$, the mesopores almost collapsed and only a few macropores existed. On the other hand, in the case of a catalyst in which platinum was supported on pellets after the pellet was produced by extrusion of hexaaluminate (M2 method catalyst), the surface area and the mesopores were well maintained even after calcination at $1,200^{\circ}C$. Also, the catalyst prepared by the M2 method showed better heat resistance in terms of platinum dispersion. The effects of preparation method and calcination temperature of Pt/hexaaluminate pellet catalysts on the decomposition of liquid propellant composed mainly of ammonium dinitramide (ADN) or hydroxyl ammonium nitrate (HAN) were investigated. It was confirmed that the decomposition onset temperature during the decomposition of ADN- or HAN- based liquid propellant could be reduced significantly by using Pt/hexaaluminate pellet catalysts. Especially, in the case of the catalyst prepared by the M2 method, the decomposition onset temperature did not show a large change even when the calcination temperature was raised at $1,200^{\circ}C$. Therefore, it was confirmed that Pt/ hexaaluminate pellet catalyst prepared by M2 method has heat resistance and potential as a catalyst for the decomposition of the eco-friendly liquid propellants.

Exposure and Risk Assessments of Multimedia of Arsenic in the Environment (환경 중 비소의 매체통합 노출평가 및 위해성평가 연구)

  • Sim, Ki-Tae;Kim, Dong-Hoon;Lee, Jaewoo;Lee, Chae-Hong;Park, Soyeon;Seok, Kwang-Seol;Kim, Younghee
    • Journal of Environmental Impact Assessment
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    • 제28권2호
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    • pp.152-168
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    • 2019
  • The element arsenic, which is abundant in the Earth's crust, is used for various industrial purposes including materials for disease treatment and household goods. Various human activities, such as the disposal of soil waste, metal mining and smelting, and combustion of fossil fuels, have caused the pollution of the environment with arsenic. Recently, guidelines for arsenic in rice have been adopted by the Korean ministry of food and drug safety to prevent health risks based on rice consumption. Because of the exposure to arsenic and its accumulation in the human body through various channels, such as air inhalation, skin contact, ingestion of drinking water, and food consumption, integrated multimedia risk assessment is required to adopt appropriate risk management policies. Therefore, integrated human health risk assessment was carried out in this study using integrated exposure assessment based on multimedia (e.g., air, water, and soil) and multi-route (e.g., oral, inhalation, and dermal) scenarios. The results show that oral uptake via drinking water is the most common pathway of arsenic into the human body, accounting for 57%-96% of the total arsenic exposure. Among various age groups, the highest exposures to arsenic were observed in infants because the body weight of infants is low and the surface areas of infant bodies are large. Based on the results of the exposure assessment, the cancer and non-cancer risks were calculated. The cancer risk for CTE and RME is in the range of 2.3E-05 to 6.7E-05 and thus is negligible because it does not exceed the cancer probability of 1.0E-04 for all age groups. On the other hand, the cancer risk for RME varies from 6.4E-05 to 1.8E-04 and from 1.3E-04 to 1.8E-04 for infants and preschool children, exceeding the excess cancer risk of 1.0E-04. The non-cancer risks range from 5.4E-02 to 1.9E-01 and from 1.5E-01 to 6.8E-01, respectively. They do not exceed the hazard index 1 for all scenarios and all ages.

Spatial and Temporal Changes in Sediments of Major Tidal Flats in the Western and Southern Korean Coasts: Grain Size, Organic Matter, Trace Metals (한반도 서·남해 주요 갯벌 퇴적물의 시·공간적 변화: 입도, 유기물, 중금속)

  • KIM, EUNYOUNG;RYU, SANG-OK;CHOI, DAE-UP;LEE, JAE-HWAN;OH, HA-NEUL;OH, SUN-KWAN;KHO, BYUNG-SEOL;KIM, YOUNG NAM;YEO, JEONG WON
    • The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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    • 제24권1호
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    • pp.54-63
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    • 2019
  • As a part of the national marine ecosystem monitoring program, the temporal and spatial variation of sedimentary environment and pollution of organic matters and trace metals from four major tidal flats, i.e., Ganghwa Is., Garolim bay, Jeung Is., Suncheon bay, was investigated for 3 yerars from 2015 to 2017. The mean grain size of the sediment was $5.0-5.3{\varnothing}$ at Ganghwa Is, $4.5-4.8{\varnothing}$ at Garolim bay, $6.1-6.5{\varnothing}$ at Jeung Is, and $8.6-8.7{\varnothing}$ at Suncheon bay. The mean grain size (Mz) tended to decrease from the north (Ganghwa Is.) to the south (Suncheon bay). The ignition loss (IL) was 15.5% in Suncheon bay in 2015, which was relatively high compared to other sites, but gradually decreased over time from 8.3% in 2016 to 7.0% in 2017. In Jeung Is. and Suncheon bay, the concentration of Zn and As exceeded the threshold effect level (TEL) at some stations, but the range of trace metals in the other sites was below the level. In Jeung Is., the Mz and concentration of trace metals except Hg was positively correlated (r= 0.40-0.88, P<0.05). On the other hand, Mz was negatively correlated with trace metals (P<0.05) in Suncheon bay. The geoaccumulation index ($I_{geo}$) to evaluate contamination status of sediments for trace metal was less than 1(not contaminated) for Cu, Zn, Pb, Cd and Hg, and 2-3 (moderately to strongly polluted) for As at several stations in Suncheon bay and Jeung Is.

Semi-quantitative Analysis of Manganese Oxide Mineral in Manganese Nodule From the East Siberian Sea (동시베리아해 망가니즈단괴의 산화망가니즈광물 반정량 분석)

  • Yu, Hye Jin;Shin, Eun Ju;Koo, Hyo Jin;Cho, Hyen Goo
    • Korean Journal of Mineralogy and Petrology
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    • 제33권4호
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    • pp.427-437
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    • 2020
  • Manganese nodules, which are evaluated as potential metal resources, have been found in the Arctic Ocean as well as in the abyssal plains of the Pacific and Indian Oceans. Manganese nodules exhibit strong variations in the morphology, internal texture, chemical composition and mineralogy as they grow. The relationship between the texture and chemical elemental composition during the growth process is well documented, but the mineral composition variation during the growth process is not. Because the manganese oxide minerals in nodules are fine-grained and poorly crystalline, quantitative analysis for the mineral composition is challenging for the bulk nodule sample. This study investigated the internal texture and Mn-oxide mineral composition of manganese nodules obtained from the East Siberian Sea. Semi-quantitative analysis was attempted for three main Mn-oxide minerals constituting the manganese nodules (i.e., todorokite, buserite and birnessite) using the peak area ratio of X-ray diffraction analysis graphs. In the East Siberian Sea manganese nodules, birnessite is more abundant than buserite or todorokite, and no correlation is found between the mineral composition and the internal texture. Instead a correlation is found between the relative content of todorokite and the lamellae depth. The todorokite content tends to increase from the surface to the core of the nodules, which can be attributed to a recrystallization process or difference in the growth rate within the nodule. This study shows that semi-quantitative analysis of manganese oxide minerals using the peak area ratio is useful in the mineralogical study of manganese nodules.

Evaluating the Capping Effects of Dredged Materials on the Contaminated Sediment for Remediation and Restoration of the West Sea-Byeong Dumping Site (서해병 폐기물 배출해역 오염퇴적물의 정화·복원을 위한 준설토 피복 효과 평가)

  • Kang, Dong Won;Lee, Kwang Sup;Kim, Young Ryun;Choi, Ki-young;Kim, Chang-joon
    • Journal of the Korean Society of Marine Environment & Safety
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    • 제28권2호
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    • pp.212-223
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    • 2022
  • For the remediation and restoration of contaminated sediment at the West Sea-Byeong dumping site, dredged materials was dumped in 2013, 2014, 2016, and 2017. The physicochemical properties and benthic fauna in surface sediments of the capping area (5 stations) and natural recovery area (2 stations) were analyzed annually from 2014 to 2020 to evaluate the capping effect of the dredged materials. The natural recovery area had a finer sediment with a mean particle size of 5.91-7.64 Φ, while the sediment in the capping area consisted of coarse-grained particles with a mean particle size of 1.47-3.01 Φ owing to the capping effect of dredged materials. Considering that the contents of organic matters (COD, TOC, and TN) and heavy metals in the capping area are approximately 50 % lower (p<0.05) than that in the natural recovery area, it is judged that there is a capping effect of dredged materials. As a result of analyzing macrobenthic assemblages, the number of species and ecological indices of the capping area were significantly lower than that of the natural recovery area (p<0.05). The number of species and ecological indices at the capping area were increased for the first four years after the capping in 2013 and 2014 and then tended to decrease thereafter. It is presumed that opportunistic species, which have rapid growth and short lifetime, appeared dominantly during the initial phase of capping, and the additory capping in 2016 and 2017 caused re-disturbance in the habitat environment. In the natural recovery and capping areas, Azti's Marine Biotic Index (AMBI) was evaluated as a fine healthy status because it maintained the level of 2nd grades (Good), whereas Benthic Pollution Index (BPI) remained at the 1st and 2nd grade. Therefore, capping of dredged materials for remediation of contaminated sediment in the dumping site has the effect of reducing the pollution level. However, in terms of the benthic ecosystem, it is recommended that the recovery trend should be monitored long-term. Additionally, it is necessary to introduce an adaptive management strategy when expanding the project to remediate the contaminated sediment at the dumping area in the future.

Ammonia Decomposition over Ni Catalysts Supported on Zeolites for Clean Hydrogen Production (청정수소 생산을 위한 암모니아 분해 반응에서 Ni/Zeolite 촉매의 반응활성에 관한 연구)

  • Jiyu Kim;Kyoung Deok Kim;Unho Jung;Yongha Park;Ki Bong Lee;Kee Young Koo
    • Journal of the Korean Institute of Gas
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    • 제27권3호
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    • pp.19-26
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    • 2023
  • Hydrogen, a clean energy source free of COx emissions, is poised to replace fossil fuels, with its usage on the rise. Despite its high energy content per unit mass, hydrogen faces limitations in storage and transportation due to its low storage density and challenges in long-term storage. In contrast, ammonia offers a high storage capacity per unit volume and is relatively easy to liquefy, making it an attractive option for storing and transporting large volumes of hydrogen. While NH3 decomposition is an endothermic reaction, achieving excellent low-temperature catalytic activity is essential for process efficiency and cost-effectiveness. The study examined the effects of different zeolite types (5A, NaY, ZSM5) on NH3 decomposition activity, considering differences in pore structure, cations, and Si/Al-ratio. Notably, the 5A zeolite facilitated the high dispersion of Ni across the surface, inside pores, and within the structure. Its low Si/Al ratio contributed to abundant acidity, enhancing ammonia adsorption. Additionally, the presence of Na and Ca cations in the support created medium basic sites that improved N2 desorption rates. As a result, among the prepared catalysts, the 15 wt%Ni/5A catalyst exhibited the highest NH3 conversion and a high H2 formation rate of 23.5 mmol/gcat·min (30,000 mL/gcat·h, 600 ℃). This performance was attributed to the strong metal-support interaction and the enhancement of N2 desorption rates through the presence of medium basic sites.

Preservation of World Records Heritage in Korea and Further Registry (한국의 세계기록유산 보존 현황 및 과제)

  • Kim, Sung-Soo
    • Journal of Korean Society of Archives and Records Management
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    • 제5권2호
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    • pp.27-48
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    • 2005
  • This study investigates the current preservation and management of four records and documentary heritage in Korea that is in the UNESCO's Memory of the World Register. The study analyzes their problems and corresponding solutions in digitizing those world records heritages. This study also reviews additional four documentary books in Korea that are in the wish list to add to UNESCO's Memory of the World Register. This study is organized as the following: Chapter 2 examines the value and meanings of world records and documentary heritage in Korea. The registry requirements and procedures of UNESCO's Memory of the World Register are examined. The currently registered records of Korea include Hunmin-Chongum, the Annals of the Choson Dynasty, the Diaries of the Royal Secretariat (Seungjeongwon Ilgi), and Buljo- Jikji-Simche-Yojeol (vol. II). These records heritage's worth and significance are carefully analyzed. For example, Hunmin-Chongum("訓民正音") is consisted of unique and systematic letters. Letters were delicately explained with examples in its original manual at the time of letter's creation, which is an unparalleled case in the world documentary history. The Annals of the Choson Dynasty("朝鮮王朝實錄") are the most comprehensive historic documents that contain the longest period of time in history. Their truthfulness and reliability in describing history give credits to the annals. The Royal Secretariat Diary (called Seungjeongwon-Ilgi("承政院日記")) is the most voluminous primary resources in history, superior to the Annals of Choson Dynasty and Twenty Five Histories in China. Jikji("直指") is the oldest existing book published by movable metal print sets in the world. It evidences the beginning of metal printing in the world printing history and is worthy of being as world heritage. The review of the four registered records confirms that they are valuable world documentary heritage that transfers culture of mankind to next generations and should be preserved carefully and safely without deterioration or loss. Chapter 3 investigates the current status of preservation and management of three repositories that store the four registered records in Korea. The repositories include Kyujanggak Archives in Seoul National University, Pusan Records and Information Center of National Records and Archives Service, and Gansong Art Museum. The quality of their preservation and management are excellent in all of three institutions by the following aspects: 1) detailed security measures are close to perfection 2) archiving practices are very careful by using a special stack room in steady temperature and humidity and depositing it in stack or archival box made of paulownia tree and 3) fire prevention, lighting, and fumigation are thoroughly prepared. Chapter 4 summarizes the status quo of digitization projects of records heritage in Korea. The most important issue related to digitization and database construction on Korean records heritage is likely to set up the standardization of digitization processes and facilities. It is urgently necessary to develop comprehensive standard systems for digitization. Two institutions are closely interested in these tasks: 1) the National Records and Archives Service experienced in developing government records management systems; and 2) the Cultural Heritage Administration interested in digitization of Korean old documents. In collaboration of these two institutions, a new standard system will be designed for digitizing records heritage on Korean Studies. Chapter 5 deals with additional Korean records heritage in the wish list for UNESCO's Memory of the World Register, including: 1) Wooden Printing Blocks(經板) of Koryo-Taejangkyong(高麗大藏經) in Haein Temple(海印寺); 2) Dongui-Bogam("東醫寶鑑") 3) Samguk-Yusa("三國遺事") and 4) Mugujeonggwangdaedaranigyeong. Their world value and importance are examined as followings. Wooden Printing Blocks of Koryo-Taejangkyong in Haein Temple is the worldly oldest wooden printing block of cannon of Buddhism that still exist and was created over 750 years ago. It needs a special conservation treatment to disinfect germs residing in surface and inside of wooden plates. Otherwise, it may be damaged seriously. For its effective conservation and preservation, we hope that UNESCO and Government will schedule special care and budget and join the list of Memory of the Word Register. Dongui-Bogam is the most comprehensive and well-written medical book in the Korean history, summarizing all medical books in Korea and China from the Ancient Times through the early 17th century and concentrating on Korean herb medicine and prescriptions. It is proved as the best clinical guidebook in the 17th century for doctors and practitioners to easily use. The book was also published in China and Japan in the 18th century and greatly influenced the development of practical clinic and medical research in Asia at that time. This is why Dongui Bogam is in the wish list to register to the Memory of the World. Samguk-Yusa is evaluated as one of the most comprehensive history books and treasure sources in Korea, which illustrates foundations of Korean people and covers histories and cultures of ancient Korean peninsula and nearby countries. The book contains the oldest fixed form verse, called Hyang-Ka(鄕歌), and became the origin of Korean literature. In particular, the section of Gi-ee(紀異篇) describes the historical processes of dynasty transition from the first dynasty Gochosun(古朝鮮) to Goguryeo(高句麗) and illustrates the identity of Korean people from its historical origin. This book is worthy of adding to the Memory of the World Register. Mugujeonggwangdaedaranigyeong is the oldest book printed by wooden type plates, and it is estimated to print in between 706 and 751. It contains several reasons and evidence to be worthy of adding to the list of the Memory of the World. It is the greatest documentary heritage that represents the first wooden printing book that still exists in the world as well as illustrates the history of wooden printing in Korea.

A Studs on Farmers Syndrome and Its Risk Factors of Vinylhouse Workers and Evaluation of Risk Factors of Vinylhouse Works (일부 농촌지역 비닐하우스 농사자들의 작업환경 및 농부증 실태와 관련요인평가)

  • Lee, Jung-Jeung
    • Journal of agricultural medicine and community health
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    • 제29권1호
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    • pp.101-119
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    • 2004
  • Objectives: In order to estimate risk factors affecting the health of vinylhouse workers and harmful environments in vinylhouse working. Methods: The investigator performed questionnaires and laboratory examinations on 102 vinylhouse workers and 69 farmers in 7 myoens (Korean subcounties). one eup (a Korean town), Goryeong-gun, Gyeongsangbuk-do between April 8 and 18, 2004 (for 11 days), and measured the heavy metal in the air and the soil, temperature, humidity, air current, harmful gases in vinylhouses. Results: Even in cloudy days, the temperature in vinylhouses in daylight was $33.4^{\circ}$ and the temperature difference between inside and outside vinylhouses was around $16^{\circ}$. Oxygen concentration was similar inside and outside vinylhouses, while carbon dioxide concentration was lower inside than outside vinylhouses. Carbon monoxide was not detected. In the air inside vinylhouses, cadmium was not detected. Lean concentration in the soil was lower inside vinylhouses than outside vinylhouses at surface, while cadmium concentration was similar inside and outside vinylhouses in the soil except some areas. Out of male vinylhouse workers. 16.4---- were positive farmer's syndrome and 49.2---- were suspicious, while out of females, 41.5---- were positive and 46.3---- were suspicious. Out of male farmers, 30.4---- were positive farmer's syndrome, while out of female farmers, 60.0---- were positive and 28.3---- were suspicious. There was no difference between vinylhouse workers and farmers in the distribution of hypertension and abnormal liver function, while diabetes mellitus was more common in farmers than in vinylhouse workers. Vinylhouse working, sex, and hours of farming per day were selected as significant variables affecting farmer's syndrome in this study, and the rate of positive farmer's syndrome was rather lower in vinylhouse workers than in farmers. Females were higher than males in the rate, and those who farmed at least 10 hours per day were higher in the rate than those who farmed less than 10 hours per day. Out of the vinylhouse workers, no differences were found between the distribution of farmer's syndrome and farming-related variables such as the total period of farming, the size of farm land, the mean farming hours per day, the number of family members who farm together, the frequency of scattering agricultural chemicals. In addition, there were no differences between the distribution and the wearing masks and protectors and personal sanitation among those who scattered agricultural chemicals by themselves. There were no differences found in blood lean concentration, urinary cadmium concentration, serum cholinesterase, and hemoglobin according to the distribution of farmer's syndrome. In the vinylhouse workers, females were higher than males in the rate of farmer's syndrome, and those who farmed at least 10 hours per day were higher in the rate than those who farmed less than 10 hours per day. Meanwhile, the rate was lower in those who slept at least 8 hours a day than in those who slept less than 8 hours. Conclusions: In conclusion, the physical environments inside vinylhouses were harmful, but no significant difference was found in harmfulness of the chemical environments. The chronic diseases such as farmer's syndrome. hypertension, diabetes, and dyshepatia were not common in the vinylhouse workers than in the farmers. Meanwhile, farmer's syndrome was more common in the vinylhouse workers who worked longer and slept less.

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The Evaluation of Radiation Dose to Embryo/Fetus and the Design of Shielding in the Treatment of Brain Tumors (임산부의 전뇌 방사선 치료에 있어서의 태아의 방사선량 측정 및 차폐 구조의 설계)

  • Cho, Woong;Huh, Soon-Nyung;Chie, Eui-Kyu;Ha, Sung-Whan;Park, Yang-Gyun;Park, Jong-Min;Park, Suk-Won
    • Journal of Radiation Protection and Research
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    • 제31권4호
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    • pp.203-210
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    • 2006
  • Purpose : To estimate the dose to the embryo/fetus of a pregnant patient with brain tumors, and to design an shielding device to keep the embryo/fetus dose under acceptable levels Materials and Methods : A shielding wall with the dimension of 1.55 m height, 0.9 m width, and 30 m thickness is fabricated with 4 trolleys under the wall. It is placed between a Patient and the treatment head of a linear accelerator to attenuate the leakage radiation effectively from the treatment head, and is placed 1 cm below the lower margin of the treatment field in order to minimize the dose to a patient from the treatment head. An anti-patient scattering neck supporters with 2 cm thick Cerrobend metal is designed to minimize the scattered radiation from the treatment fields, and it is divided into 2 section. They are installed around the patient neck by attach from right and left sides. A shielding bridge for anti-room scattered radiation is utilized to place 2 sheets of 3 mm lead plates above the abdomen to setup three detectors under the lead sheets. Humanoid phantom is irradiated with the same treatment parameters, and with and without shielding devices using TLD, and ionization chambers with and without a build-up cap. Results : The dose to the embryo/fetus without shielding was 3.20, 3.21, 1.44, 0.90 cGy at off-field distances of 30, 40, 50, and 60 cm. With shielding, the dose to embryo/fetus was reduced to 0.88, 0.60, 0.35, 0.25 cGy, and the ratio of the shielding effect varied from 70% to 80%. TLD results were 1.8, 1.2, 0.8, 1.2, and 0.8 cGy. The dose measured by the survey meter was 10.9 mR/h at the patient's surface of abdomen. The dose to the embryo/fetus was estimated to be about 1 cGy during the entire treatment. Conclusion : According to the AAPM Report No 50 regarding the dose limit of the embryo/fetus during the pregnancy, the dose to the embryo/fetus with little risk is less than 5 cGy. Our measurements satisfy the recommended values. Our shielding technique was proven to be acceptable.