• Title/Summary/Keyword: Safety Characteristics

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Mechanism of steel pipe reinforcement grouting based on tunnel field measurement results (터널 현장 계측결과를 통한 강관보강 그라우팅의 거동 메커니즘)

  • Shin, Hyunkang;Jung, Hyuksang;Lee, Yong-joo;Kim, Nag-young;Ko, Sungil
    • Journal of Korean Tunnelling and Underground Space Association
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    • v.23 no.3
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    • pp.133-149
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    • 2021
  • This study aims to report the behavioral mechanism of steel pipe reinforcement grouting, which is being actively used to ensure the stability of the excavation surface during tunnel excavation, based on measurements taken at the actual site. After using a 12 m steel pipe attached with a shape displacement meter and a strain gauge to reinforce the actual tunnel surface, behavioral characteristics were identified by analyzing the measured deformation and stress of the steel pipe. Taking into account that the steel pipes were overlapped every 6 m, the measured data up to 7 m of excavation were used. In addition, the behavioral characteristics of the steel pipe reinforcement according to the difference in strength were also examined by applying steel pipes with different allowable stresses (SGT275 and SGT550). As a result of analyzing the behavior of steel pipes for 7 hours after the first excavation for 1 m and before proceeding with the next excavation, the stress redistribution due to the arching effect caused by the excavation relaxation load was observed. As excavation proceeded by 1 m, the excavated section exhibited the greatest deformation during excavation of 4 to 6 m due to the stress distribution of the three-dimensional relaxation load, and deformation and stress were generated in the steel pipe installed in the ground ahead of the tunnel face. As a result of comparing the behavior of SGT275 steel pipe (yield strength 275 MPa) and SGT550 steel pipe (yield strength 550 MPa), the difference in the amount of deformation was up to 18 times and the stress was up to 12 times; the stronger the steel pipe, the better it was at responding to the relaxation load. In this study, the behavior mechanism of steel pipe reinforcement grouting in response to the arching effect due to the relaxation load was identified based on the measured data during the actual tunnel excavation, and the results were reported.

Study of Minimum Passage Size of Subterranean Termites (Reticulitermes speratus kyushuensis) (국내 흰개미(Reticulitermes speratus kyushuensis)의 최소 통과 직경 연구)

  • Kim, Sihyun;Lee, Sangbin;Lim, Ikgyun
    • Korean Journal of Heritage: History & Science
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    • v.53 no.4
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    • pp.188-197
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    • 2020
  • Termites play an important role as decomposers of the forest ecosystem, while simultaneously causing enormous damage to wooden structures. Currently, two species of subterranean termites have been reported in Korea, and termite damage to historical wooden buildings is occurring nationwide due to climate change, forest fertility, and the locational characteristics of historical wooden buildings. Subterranean termites make their nests underground or inside timber. Termites move underground and access wooden structures through the lower parts of the buildings, adjacent to the ground. Once termites attack the wooden structures, it not only spoils the authenticity of cultural heritage structure, but also hampers structural stability due to the decrease in the strength of the material. Therefore, it is important to prevent termite damage before it occurs. Chemical treatments are mainly used in Korea to control and prevent the damage. In foreign countries, physical barriers are also used to prevent entry to wooden buildings, along with chemical treatments. Physical barriers involve installing nets or particles that termites cannot pass through in the lower part of the building, around the pipes, and between the edges of the building or exterior walls and interior materials. Advantages of a physical barrier are that it is an eco-friendly method, maintains long-term effect after installation, and does not require the use of chemical treatments. Prior to applying physical barriers, studies into the characteristics of termite species must be undertaken. In this study, we evaluated the minimum passage size that each caste of Reticulitermes speratus kyushuensis can move through. We found that workers, soldiers, and secondary reproductive termites were able to pass through diameters of 0.7mm, 0.9mm, and 1.1mm respectively. Head height of termites was an important factor in determining the minimum passing size. Results from the current study will be used as a basis to design the mesh size for physical barriers to prevent damage by termites in historical wooden buildings in Korea.

Detection of flash drought using evaporative stress index in South Korea (증발스트레스지수를 활용한 국내 돌발가뭄 감지)

  • Lee, Hee-Jin;Nam, Won-Ho;Yoon, Dong-Hyun;Mark, D. Svoboda;Brian, D. Wardlow
    • Journal of Korea Water Resources Association
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    • v.54 no.8
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    • pp.577-587
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    • 2021
  • Drought is generally considered to be a natural disaster caused by accumulated water shortages over a long period of time, taking months or years and slowly occurring. However, climate change has led to rapid changes in weather and environmental factors that directly affect agriculture, and extreme weather conditions have led to an increase in the frequency of rapidly developing droughts within weeks to months. This phenomenon is defined as 'Flash Drought', which is caused by an increase in surface temperature over a relatively short period of time and abnormally low and rapidly decreasing soil moisture. The detection and analysis of flash drought is essential because it has a significant impact on agriculture and natural ecosystems, and its impacts are associated with agricultural drought impacts. In South Korea, there is no clear definition of flash drought, so the purpose of this study is to identify and analyze its characteristics. In this study, flash drought detection condition was presented based on the satellite-derived drought index Evaporative Stress Index (ESI) from 2014 to 2018. ESI is used as an early warning indicator for rapidly-occurring flash drought a short period of time due to its similar relationship with reduced soil moisture content, lack of precipitation, increased evaporative demand due to low humidity, high temperature, and strong winds. The flash droughts were analyzed using hydrometeorological characteristics by comparing Standardized Precipitation Index (SPI), soil moisture, maximum temperature, relative humidity, wind speed, and precipitation. The correlation was analyzed based on the 8 weeks prior to the occurrence of the flash drought, and in most cases, a high correlation of 0.8(-0.8) or higher(lower) was expressed for ESI and SPI, soil moisture, and maximum temperature.

Exploratory Study of Person Centered Care Practice in Korean Long-term Care Facilities using DCM(Dementia Care Mapping) as a tool (DCM(Dementia Care Mapping)을 활용한 한국 요양시설에서의 사람중심케어 실천의 탐색적 연구)

  • Kim, Dongseon
    • 한국노년학
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    • v.41 no.2
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    • pp.197-215
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    • 2021
  • This study aims to evaluate Person Centered Care practice and characteristics of care services in Korean long-term care facilities using Dementia Care Mapping as a tool. DCM, systematic observational evaluation tool for measuring dementia patients' QOL, was transformed into self-report rating scale. The process of transforming DCM into a scale of 34 items involves operationalization of DCM concepts and it's adaptation into Korean long-term care practices. Review by research team of Bradford university was added to maintain DCM concept and meaning in this scale. The scale with Cronbach alpha of .88 was surveyed on 343 care workers. Survey result shows PCC value practiced by them is 3.77(of 5 likert scale) and values on each categories of PCC reveal the characteristics of care in Korean facilities; attachment(4.02), comfort(3.95), inclusion(3.89), identity(3.67) and occupation(3.41). Dementia care in Korean facilities focuses on recipients'safety, comfort but lacks individualistic care and the meaningful and fulfilling occupation for patients. Looking at the organizational and individual factors influencing DCM values, the small facilities showed higher PCC values and there are no significant difference in PCC values between public and private facilities. Managers and care workers with career of 1~2 years showed higher PCC values compared to other career ranks and lengthes. This study suggests care practice should be centered on personhood of patients in long-term care facilities, for which introduction of unit care and education of PCC for service providers including support personnel are needed. DCM and Korean DCM scale developed in this study are suggested for the PCC-based assessment on care quality.

Development of tracer concentration analysis method using drone-based spatio-temporal hyperspectral image and RGB image (드론기반 시공간 초분광영상 및 RGB영상을 활용한 추적자 농도분석 기법 개발)

  • Gwon, Yeonghwa;Kim, Dongsu;You, Hojun;Han, Eunjin;Kwon, Siyoon;Kim, Youngdo
    • Journal of Korea Water Resources Association
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    • v.55 no.8
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    • pp.623-634
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    • 2022
  • Due to river maintenance projects such as the creation of hydrophilic areas around rivers and the Four Rivers Project, the flow characteristics of rivers are continuously changing, and the risk of water quality accidents due to the inflow of various pollutants is increasing. In the event of a water quality accident, it is necessary to minimize the effect on the downstream side by predicting the concentration and arrival time of pollutants in consideration of the flow characteristics of the river. In order to track the behavior of these pollutants, it is necessary to calculate the diffusion coefficient and dispersion coefficient for each section of the river. Among them, the dispersion coefficient is used to analyze the diffusion range of soluble pollutants. Existing experimental research cases for tracking the behavior of pollutants require a lot of manpower and cost, and it is difficult to obtain spatially high-resolution data due to limited equipment operation. Recently, research on tracking contaminants using RGB drones has been conducted, but RGB images also have a limitation in that spectral information is limitedly collected. In this study, to supplement the limitations of existing studies, a hyperspectral sensor was mounted on a remote sensing platform using a drone to collect temporally and spatially higher-resolution data than conventional contact measurement. Using the collected spatio-temporal hyperspectral images, the tracer concentration was calculated and the transverse dispersion coefficient was derived. It is expected that by overcoming the limitations of the drone platform through future research and upgrading the dispersion coefficient calculation technology, it will be possible to detect various pollutants leaking into the water system, and to detect changes in various water quality items and river factors.

Quality Characteristics of the Meat Products Reached Expiration Date in Korean Market (유통기한이 임박한 한국산 식육제품의 품질 특성)

  • Yim, Dong-Gyun;Yang, Mi Ra;No, Gun Ryoung;Choi, Dong Sun;Jang, Hyeon Myeong;Kim, Tae Yeon;Jo, Jang Woong;Yang, Seung Chang;Kim, Sam Woong;Kim, Il-Suk
    • Journal of agriculture & life science
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    • v.50 no.4
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    • pp.169-177
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    • 2016
  • This study was carried out to compare microbiological and hygienic quality characteristics of the products reached expiration date among meat products distributing in markets. A total of 20 meat products(6 hams, 3 bacons and 11 sausages) were examined for analyses of pH, Aw, TBARS, VBN, total aerobic microbial counts, and meat colors. The pH values of samples were between 5.33 and 6.59. The water activity (Aw) of samples ranged 0.90-0.93. TBARS and VBN values of samples were 0.11-0.59 and 2.37~14.75, respectively. The contaminated levels of total aerobic bacteria were less than 2.80 CFU/g. In meat color, L*, a*, and b* values of samples were in the range of 56-72, 5.2-34 and 0.7-16, respectively. It is suggested that the quality difference of meat products is attributed to the different additives and manufacturing processes. Therefore, we suggest that the results of this study are not only applied for evaluation of the microbiological and hygienic safety but also served as fundamental information for re-establishing the shelf-life of meat products.

Analysis of Factors Affecting the Length of Stay in Children(Aged 0 to 12) with Injuries: Centering Around the Data from the Korea National Hospital Discharge In-Depth Injury Surveys (어린이(0-12세) 손상환자의 재원일수에 미치는 요인분석: 퇴원손상심층자료를 중심으로)

  • Lee Chae Kyung
    • The Journal of the Convergence on Culture Technology
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    • v.9 no.3
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    • pp.137-143
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    • 2023
  • This study was conducted to analyze factors affecting the length of stay in children with injuries by determining relationships between length of stay and characteristics of children(aged 0 to 12) with injuries. 7,804 patients aged 0 to 12 who participated in the Korea Nation Hospital Discharge In-Depth Injury Surveys, got a diagnosis of sequelae of injuries and of other consequences of external causes(S00-T98), and were discharged between 1 January 2016 and 31 December 2020 were investigated. A frequency analysis, independent samples t-test, and ANOVA were performed. Also, to identify factors affecting the length of stay, a regression analysis was performed. The average length of stay for the patients investigated in this study was 5.5 days. The length of stay for school-age children(aged 7 to 12) and children who had either public or private coverage was higher than that for preschoolers(aged 0 to 6) and children who didn't have public or private coverage, respectively. The length of stay for children admitted to a hospital in a rural area(Jeolla-do or Gyeongsang-do) was higher than that for children admitted to a hospital in a metropolitan area and the length of stay for children admitted to a hospital that had 100-299 hospital beds was relatively long. However, children who first visited a hospital for outpatient care stayed relatively short in hospital and children who had been burned or injured in traffic crashes stayed relatively long in hospital. Children who got a secondary diagnosis and had a principal procedure or who died after being discharged were in hospital for a long time. The findings of this study shall be useful, as they identified characteristics related to the length of stay for Korean children with injuries and factors that determine the length of stay for those children by analyzing the national dataset, or more specifically, the data from the Korea National Hospital Discharge In-Depth Injury Surveys. The risk of child injuries can be easily reduced by taking actions to prevent them and providing safety education programs. The present study has provided essential baseline data for the provision of aggressive care for child injuries and the establishment of a range of policies for child injury prevention.

Analysis on dynamic numerical model of subsea railway tunnel considering various ground and seismic conditions (다양한 지반 및 지진하중 조건을 고려한 해저철도 터널의 동적 수치모델 분석)

  • Changwon Kwak;Jeongjun Park;Mintaek Yoo
    • Journal of Korean Tunnelling and Underground Space Association
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    • v.25 no.6
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    • pp.583-603
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    • 2023
  • Recently, the advancement of mechanical tunnel boring machine (TBM) technology and the characteristics of subsea railway tunnels subjected to hydrostatic pressure have led to the widespread application of shield TBM methods in the design and construction of subsea railway tunnels. Subsea railway tunnels are exposed in a constant pore water pressure and are influenced by the amplification of seismic waves during earthquake. In particular, seismic loads acting on subsea railway tunnels under various ground conditions such as soft ground, soft soil-rock composite ground, and fractured zones can cause significant changes in tunnel displacement and stress, thereby affecting tunnel safety. Additionally, the dynamic response of the ground and tunnel varies based on seismic load parameters such as frequency characteristics, seismic waveform, and peak acceleration, adding complexity to the behavior of the ground-tunnel structure system. In this study, a finite difference method is employed to model the entire ground-tunnel structure system, considering hydrostatic pressure, for the investigation of dynamic behavior of subsea railway tunnel during earthquake. Since the key factors influencing the dynamic behavior during seismic events are ground conditions and seismic waves, six analysis cases are established based on virtual ground conditions: Case-1 with weathered soil, Case-2 with hard rock, Case-3 with a composite ground of soil and hard rock in the tunnel longitudinal direction, Case-4 with the tunnel passing through a narrow fault zone, Case-5 with a composite ground of soft soil and hard rock in the tunnel longitudinal direction, and Case-6 with the tunnel passing through a wide fractured zone. As a result, horizontal displacements due to earthquakes tend to increase with an increase in ground stiffness, however, the displacements tend to be restrained due to the confining effects of the ground and the rigid shield segments. On the contrary, peak compressive stress of segment significantly increases with weaker ground stiffness and the effects of displacement restrain contribute the increase of peak compressive stress of segment.

Research on the Relation between Musculoskeletal symptoms and Diagnosis using Moire Topography among Workers at an Automobile Manufacturing Plant (자동차회사 근로자를 대상으로 한 근골격계 자각증상과 moire 영상 진단과의 관계 연구)

  • Chun Eun-Joo;Lee Young-Gil;Jahng Doo-Sub;Lee Ki-Nam;Song Yung-Sun
    • Journal of Society of Preventive Korean Medicine
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    • v.5 no.2
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    • pp.69-92
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    • 2001
  • The purposes of this study were to offer foundation making more certain standards of musculoskeletal disorder diagnosis, We researched musculoskeletal symptoms degrees, frequencies, and cares and then examined relation between musculoskeletal symptoms and diagnosis of musculoskeletal conditions using moire topography among workers at an automobile manufacturing plant. Therefore we propose the possibility of moire topography as diagnosing utilities of musculoskeletal disorders. Methods: This study was to examine the general characteristics, complaints of musculoskeletal symptoms, and work-related musculoskeletal disorder rates of cervicobrachial and lumbar area by survey among 435 workers at an automobile manufacturing plant and then to show each frequency and percentage, In the diagnosis using moire topography, we studied pain control necessity of cervicobrachial and lumbar area, 435 subjects were classified by 5 levels: A(no symptoms), B(need management), C(need treatment) and then more divided by B1(light symptoms)/B2(heavy symptoms), C1(light symptoms)/C2(heavy symptoms), And musculoskeletal areas were divided by 2 parts, cervicobrachial area(neck, shoulder, arm&elbow, and wrist&hand) and lumbar area, Then, frequency and percentage of each musculoskeletal areas(cervicobrachial and lumbar area) were appeared. At last, Pearson's chi-square test analysis was utilized to observe the relation between diagnosis using moire topography and general characteristics and the relation between diagnosis using moire topography and work-related complaint of musculoskeletal symptoms of cervicobrachial and lumbar area, Results: The subjects employed for this research were categorized into; by gender, all of them were males(l00%): by age, under 35 years 12 %, 36-40 years 56.3%, 41-45 years 26.3 %, and above 46 years 5.3% with 36-40 years accounting for most of it. By living location, owned houses represented 69.7%, rented houses 23.4%, monthly-rented 1.6%, the others 5.3%; by education, middle school and lower represented 3.0%, high school 89.4%, and junior college and higher 7.6% with high school occupying most of the group. By marital status, married represented 95.2%, unmarried 4.1%, and the others 0.7% with most of them married; by alcohol, drinking represented 81.8% and non-drinking 18.2%; by smoking status, smoking represented 53.6%, non-smoking 46.4% with no big difference between them. By working time(hours/week), below 50 represented 26.9%, 50-60 67.6%, above 60 5.5%; by working time(hours/day), below 9 represented 21.6%, 10-12 73.1%, above 13 5.3%; by job tenure(years), below 10 represented 25.1%, 11-15 54.3%, 16-20 15.2%, above 21 5.5%. By personal income per year, below 30 million won represented 11.0%, 30-40 84.8%, above 40 4.1%; by sleeping hours, below 6 hours represented 26.7%, 7-8 hours 69.9%, above 9 hours 3.4%. Complaint rates of musculoskeletal symptoms and work-related musculoskeletal disorder rates were 63.9% and 54.9% with shoulder area occupying most of both them. By pain degree of musculoskeletal symptoms, shoulder area represented $2.73{\pm}0.84$, lumbar area $2.66{\pm}0.86$, wrist and hand area $2.59{\pm}0.86$, neck area $2.55{\pm}0.74$, and arm and elbow area $2.48{\pm}0.71$. By cares about musculoskeletal symptoms, taking medication or care represented 34.4%-46.7%, absence or leave 15.4%-28.7%, and job transfer 6.3%-11.5%. So experienced cases more than one thing among cares about musculoskeletal symptoms represented 39.6%-54%. In the diagnosis using moire topography, pain control necessity of cervicobrachial area was shown below; A(no symptoms) 20.7%, B1(need management/light symptoms) 64.6%, B2(need management/heavy symptoms) 11.5%, C1(need treatment/light symptoms) 3.0%, C2(need treatment/heavy symptoms) 0.2%. By lumbar area, A(no symptoms) 8.7%, B1(need management/light symptoms) 52.2%, B2(need management/heavy symptoms) 30.3%, C1(need treatment/light symptoms) 8.7%, C2(need treatment/heavy symptoms) was none. In the relation between pain control necessity and general characteristics, age(P=0.013), education(P=0.000), and job tenure(P=0.012) with pain control necessity showed differences with significance. The relation between pain control necessity and complaint of musculoskeletal symptoms of cervicobrachial and lumbar area showed no difference with significance; in cervicobrachial area represented P=0.708, lumbar area P=0.318 Conclusions: This study for musculoskeletal symptoms on workers at automobile manufacturing plant showed that complaint rates of musculoskeletal symptoms for cervicobrachial and lumbar area were so high, 63.9%. But Pearson's chi-square test analysis was utilized to study the relation between musculoskeletal symptoms and the diagnosis using moire topography, showed no differences with significance. They have no differences with significance, but the prevalence rates of diagnosis using moire topography for cervicobrachial and lumbar area were more higher than complaint rates of musculoskeletal symptoms; complaint rates of musculoskeletal symptoms were 52.4%, 34.5% and the diagnosis using moire topography were 79.3%, 91.3% for cervicobrachial and lumbar area. The results of this study indicate that the diagnosis using moire topography can find weak musculoskeletal disorders that an individual can not feel, not be judged work-related musculoskeletal disease. Therefore, this study has an important meaning that diagnosis using moire topography can predict and control own physical condition complete musculoskeletal disorders beforehand, since oriental medicine theory considers that prevention is important.

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Medical Radiation Exposure Dose of Workers in the Private Study of the Job Function (의료기관 방사선 종사자의 직무별 개인피폭선량에 관한 연구)

  • Kang, Chun-Goo;Oh, Ki-Baek;Park, Hoon-Hee
    • The Korean Journal of Nuclear Medicine Technology
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    • v.15 no.2
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    • pp.3-12
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    • 2011
  • Purpose: With increasing medical use of radiation and radioactive isotopes, there is a need to better manage the risk of radiation exposure. This study aims to grasp and analyze the individual radiation exposure situations of radiation-related workers in a medical facility by specific job, in order to instill awareness of radiation danger and to assist in safety and radiation exposure management for such workers. Materials and Methods: From January 1, 2010 December 31, 2010, medical practitioners working in the radiation is classified as a regular personal radiation dosimetry, and subsequently one year 540 people managed investigation department to target workers, dose sectional area, working period, identify the job function-related tasks for a deep dose, respectively, the annual average radiation dose were analyzed. Frequency analysis methods include ANOVA was performed. Results: Medical radiation workers in the department an annual radiation dose of Nuclear and 4.57 mSv a was highest, dose zone-specific distribution of nuclear medicine and in the 5.01~19.05 mSv in the high dose area distribution showed departmental radiation four of the annual radiation dose of Nuclear and 7.14 mSv showed the highest radiation dose. More work an average annual radiation dose according to the job function related to the synthesis of Cyclotron to 17.47 mSv work showed the highest radiation dose, Gamma camera Cinema Room 7.24 mSv, PET/CT Cinema Room service is 7.60 mSv, 2.04 mSv in order of intervention high, were analyzed. Working period, according to domain-specific average annual dose of radiation dose from 10 to 14 in oral and maxillofacial radiology practitioners as high as 1.01~3.00 mSv average dose showed the Department of Radiology, 1-4 years, 5-9 years, respectively, 1.01 workers~8.00 mSv in the range of the most high-dose region showed the distribution, nuclear medicine, and the 1-4 years, 5-9 years 3.01~19.05 mSv, respectively, workers of the highest dose showed the distribution of the area in the range of 10 to 14 years, Workers at 15-19 3.01~15.00 mSv, respectively in the range of the high-dose region were distributed. Conclusion: These results suggest that medical radiation workers working in Nuclear Medicine radiation safety management of the majority of the current were carried out in the effectiveness, depending on job characteristics has been found that many differences. However, this requires efforts to minimize radiation exposure, and systematic training for them and for reasonable radiation exposure management system is needed.

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