• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.33 no.2
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• pp.230-246
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• 2023

Objectives: The climate crisis has arrived and heat-related illnesses are increasing. It is necessary to discover new high-heat risk industries and understand the environment . It is also necessary to prioritize risks of industries that have not been included in the management target to date. The study was intended to monitor and evaluate the thermal risk of high-priority workplaces. Methods: A prioritization method was developed based on five factors: occurrence of and death due to heat-related illnesses, work environment monitoring, indoor work rate, small heat source, and limited heat dissipation. it, was applied to industrial accidents caused by heat-related illnesses. Wet bulb temperature index and apparent temperature were measured in July and August at 24 workplaces in seven industries and assessed for thermal risk. Results: The wet bulb temperature index was in the range of 23.8~31.9℃, and exposure limits were exceeded in the growing of crops, food services activities and accommodation, and building construction. The apparent temperature was in the range of 26.8~36.7℃, and exceeded the temperature standard for issuing heatwave warnings in growing of crops, food services activities and accommodation, warehousing, welding, and building construction. Both temperature index in growing of crops and building construction were higher than the outside air temperature. Conclusions: In the workplace, risks in industries that have not be controlled and recognized through existing systems was identified. it is necessary to provide break times according to the work-rest time ratio required during dangerous time period.

• Radiation Oncology Journal
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• v.36 no.1
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• pp.63-70
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• 2018

Purpose: The objective of this study was to compare dosimetric characteristics of three-dimensional conformal radiotherapy (3D-CRT) and two types of intensity-modulated radiotherapy (IMRT) which are step-and-shoot intensity modulated radiotherapy (s-IMRT) and modulated arc therapy (mARC) for thoracic esophageal cancer and analyze whether IMRT could reduce organ-at-risk (OAR) dose. Materials and Methods: We performed 3D-CRT, s-IMRT, and mARC planning for ten patients with thoracic esophageal cancer. The dose-volume histogram for each plan was extracted and the mean dose and clinically significant parameters were analyzed. Results: Analysis of target coverage showed that the conformity index (CI) and conformation number (CN) in mARC were superior to the other two plans (CI, p = 0.050; CN, p = 0.042). For the comparison of OAR, lung V5 was lowest in s-IMRT, followed by 3D-CRT, and mARC (p = 0.033). s-IMRT and mARC had lower values than 3D-CRT for heart $V_{30}$ (p = 0.039), $V_{40}$ (p = 0.040), and $V_{50}$ (p = 0.032). Conclusion: Effective conservation of the lung and heart in thoracic esophageal cancer could be expected when using s-IMRT. The mARC was lower in lung $V_{10}$, $V_{20}$, and $V_{30}$ than in 3D-CRT, but could not be proven superior in lung $V_5$. In conclusion, low-dose exposure to the lung and heart were expected to be lower in s-IMRT, reducing complications such as radiation pneumonitis or heart-related toxicities.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.27 no.12
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• pp.831-836
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• 2014

One-dimensional (1D) photonic crystals (PCs) were prepared by $TeO_x(2<x<3)/SiO_2$ with the difference refractive index, and fabricated by sputtering technique from a $TeO_2$ and $SiO_2$ target. The $TeO_x$(2$Ar:O_2=40:10$). A 10-pair $TeO_x(2<x<3)/SiO_2$ 1D PCs were fabricated with the structure parameters of filling factor=0.5185, and period=410 nm. The properties of 1D PCs with and without a defect layer were evaluated by UV-VIS-NIR. A normal mode 1D PC have a photonic band gap (PBG) in the near infrared (NIR) region from 1,203 to 1,421 nm. In the case of 1D PC containing a defect layer, a defect level appears at 1,291 nm. The measured transmittance (T) spectra are nearly corresponding to calculated results. After He-Cd laser exposure, the defect level is shifted from 1,291 nm to 1,304 nm.

• The Journal of Korean Society for Radiation Therapy
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• v.20 no.1
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• pp.11-15
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• 2008

Purpose: The goal of radiation treatment is to deliver a prescribed radiation dose to the target volume accurately while minimizing dose to normal tissues. In this paper, we comparing the dose distribution between three dimensional conformal radiation radiotherapy (3D-CRT) and helical tomotherapy (TOMO) plan for partial breast cancer. Materials and Methods: Twenty patients were included in the study, and plans for two techniques were developed for each patient (left breast:10 patients, right breast:10 patients). For each patient 3D-CRT planning was using pinnacle planning system, inverse plan was made using Tomotherapy Hi-Art system and using the same targets and optimization goals. We comparing the Homogeneity index (HI), Conformity index (CI) and sparing of the organs at risk for dose-volume histogram. Results: Whereas the HI, CI of TOMO was significantly better than the other, 3D-CRT was observed to have significantly poorer HI, CI. The percentage ipsilateral non-PTV breast volume that was delivered 50% of the prescribed dose was 3D-CRT (mean: 40.4%), TOMO (mean: 18.3%). The average ipsilateral lung volume percentage receiving 20% of the PD was 3D-CRT (mean: 4.8%), TOMO (mean: 14.2), concerning the average heart volume receiving 20% and 10% of the PD during treatment of left breast cancer 3D-CRT (mean: 1.6%, 3.0%), TOMO (mean: 9.7%, 26.3%) Conclusion: In summary, 3D-CRT and TOMO techniques were found to have acceptable PTV coverage in our study. However, in TOMO, high conformity to the PTV and effective breast tissue sparing was achieved at the expense of considerable dose exposure to the lung and heart.

• Asian Pacific Journal of Cancer Prevention
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• v.15 no.12
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• pp.5043-5047
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• 2014

Nowadays increasing effectiveness in cancer therapy and investigation of formation of new strategies that enhance antiproliferative activity against target organs has become a subject of interest. Although the molecular mechanisms of apoptosis can not be fully explained, it is known that cell suicide program existing in their memory genetically is activated by pathophysiological conditions and events such as oxidative stress. Low pressure (hypobaric) conditions that create hypoxia promote apoptosis by inhibiting cell cycling. In this study, determination of the effects of fractional hypobaric applications at different times on HeLa cells at cellular and molecular levels were targeted. Experiments were carried out under hypobaric conditions (35.2 kPa) in a specially designed hypobaric cabin including 2% $O_2$ and 98% N. Application of fractional hypobaric conditions was repeated two times for 3 hours with an interval of 24 hours. At the end of the implementation period cells were allowed to incubate for 24 hours for activation of repair mechanisms. Cell kinetic parameters such as growth rate (MTT) and apoptotic index were used in determination of the effect of hypobaric conditions on HeLa cells. Also in our study expression levels of the Bcl-2 gene family that have regulatory roles in apoptosis were determined by the RT-PCR technique to evaluate molecular mechanisms. The results showed that antiproliferative effect of hypobaric conditions on HeLa cells started three hours from the time of application and increased depending on the period of exposure. While there was a significant decrease in growth rate values, there was a significant increase in apoptotic index values (p<0.01). Also molecular studies showed that hypobaric conditions caused a significant increase in expression level of proapoptotic gene Bax and significant decrease in antiapoptotic Bfl-1. Consequently fractional application of hypobaric conditions on HeLa cell cultures increased both antiproliferative and apoptotic effects and these effects were triggered by the Bax gene.

• Journal of Korean Society of Environmental Engineers
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• v.33 no.1
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• pp.60-70
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• 2011

The sediment removal index derived from the chemical contaminants, $CI_{HC}$, is currently in use to identify and define the spatial extent of the contaminated sediments in the sea. In order to analyze the sensitivity of the ecological and human risk associated with contaminated sediment, we evaluated five hypothetical contaminated sediments, whose $CI_{HC}$ values are identical but consisted of different contaminant contents, using $TrophicTrace^{(R)}$ model dedicated to evaluate sediment risk, against the resident greenling (Hexagrammos otakii) and humans by calculating No-Observed-Adverse-Effect-Level based Toxicity Quotient (NOAEL TQ) and Lowest-Observed-Adverse-Effect-Level based Toxicity Quotient (LOAEL TQ), and cancer risks and hazard indices (HI), respectively, based on the site conceptual model and exposure assumptions of fish ingestion to human receptor populations. NOAEL and LOAEL TQ values varied as much as a factor of 2 among 5 hypothetical sediments. Chemical element specific contribution to the carcinogenic risk and HI varied also greatly in these sediments. The reason for this significant dissimilarity in ecological and human risk stems from the different risk of each contaminant to the resident fish and human receptor. When the conceptual food web model is constructed for the target biological species for a given site, the ecological and human risk analysis considering trophic transfer of contaminants will add a ecosystem based tool for the management of contaminated sediments.

• Journal of radiological science and technology
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• v.38 no.2
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• pp.107-114
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• 2015

The purpose is reducing radiation dose while maintaining of image quality in liver dynamic CT(LDCT) scan, by protocols generally used and the tube voltage set at a low level protocol compared to the radiation dose and image quality. The target is body mass index, 18.5~24 patients out of 40 patients who underwent the ACT(abdominal CT). Group A(tube voltage : 120kVp, SAFIRE strength 1) of 20 people among 40 people, to apply the general abdominal CT scan protocol, group B(tube voltage : 100kVp, apply SAFIRE strength 0~5) was 20 people, set a lower tube voltage. Image quality evaluation was setting a region of interest(ROI) in the liver parenchyma, aorta, superior mesenteric artery (SMA), celiac trunk, visceral fat of arterial phase. In the ROI were compared by measuring the noise, signal to noise ratio(SNR), contrast to noise ratio(CNR), CT number. In addition, qualitative assessments to evaluate two people in the rich professional experience in Radiology by 0-3 points. We compared the total radiation dose, dose length product(DLP) and effective dose, volume computed tomography dose index(CTDIvol). The higher SAFIRE in the tube voltage 100 kVp, noise is reduced, CT number was increased. Thus, SNR and CNR was increased higher the SAFIRE step. Compared with the tube voltage 120kVp, noise, SNR, CNR was most similar in SAFIRE strength 2 and 3. Qualitative assessment SAFIRE strength 2 is the most common SAFIRE strength 2 the most common qualitative assessment, if the tube voltage of 100kVp when the quality of the images better evaluated was SAFIRE strength 1. Dose was reduced from 21.69%, in 100kVp than 120kVp. In the case of a relatively high BMI is not LDCT scan, When it is shipped from the factory tube voltage is set higher, unnecessary radiation exposure when considering the reality that is concerned, when according to the results of this study, set a lower tube voltage and adjust the SAFIRE strength to 1 or 2, the radiation without compromising image quality amount also is thought to be able to be reduced.

• Progress in Medical Physics
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• v.26 no.4
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• pp.258-266
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• 2015

The modern radiotherapy technique which delivers a large amount of dose to patients asks to confirm the positions of patients or tumors more accurately by using X-ray projection images of high-definition. However, a rapid increase in patient's exposure and image information for CT image acquisition may be additional burden on the patient. In this study, by introducing structural similarity (SSIM) index that can effectively extract the structural information of the image, we analyze the differences between daily acquired x-ray images of a patient to verify the accuracy of patient positioning. First, for simulating a moving target, the spherical computational phantoms changing the sizes and positions were created to acquire projected images. Differences between the images were automatically detected and analyzed by extracting their SSIM values. In addition, as a clinical test, differences between daily acquired x-ray images of a patient for 12 days were detected in the same way. As a result, we confirmed that the SSIM index was changed in the range of 0.85~1 (0.006~1 when a region of interest (ROI) was applied) as the sizes or positions of the phantom changed. The SSIM was more sensitive to the change of the phantom when the ROI was limited to the phantom itself. In the clinical test, the daily change of patient positions was 0.799~0.853 in SSIM values, those well described differences among images. Therefore, we expect that SSIM index can provide an objective and quantitative technique to verify the patient position using simple x-ray images, instead of time and cost intensive three-dimensional x-ray images.

• Journal of Food Hygiene and Safety
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• v.16 no.1
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• pp.21-26
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• 2001

Risk assessment traditionally are conducted on individual chemicals; however, humans are exposed to multiple chemicals in daily life. The organophosphorus (OP) pesticides are considered in a single risk assessment because they act by a common mechanism of toxicity, and there is likely to be expose to multiple OP pesticides simultaneously or sequentially. The OP pesticides act by inhibiting the enzyme acetylcholinesterasc (AChE) and have available extensive database. AChE is widely distributed throughout the body, most importantly in the nervous system. Inhibition of AChE results in accumulation of acetylcholine in the nervous system that results in clinical signs of cholinergic toxicity, including increased salivation and lacrimation, nausea and vomiting, muscle fasciculation, lethargy and fatigue, among others. To conduct an exposure assessment for pesticides in the diet, we need to know the food consumption patterns of the populations, and the pesticide residue levels in the foods that are consumed. This study was conducted to identify cumulative dietary risk due to multiple OP pesticides that can be exposed through various foods. Total 22 food samples including cereals, vegetables and fruits were collected randomly two times from food markets in several sites (4 cities). The subjected foods were selected by regarding of highly consumed foods to general Korean people. The 12 OP pesticides including Acephate, Azinphos-methyl, Chlorpyrifos, and Diazinon were monitored. For the exposure assessment, general adult group of 60 kg body weight was regarded as target population and food consumption data suggested by Lee et al. (2000) were used as consumed value of individual food. Analyses of samples for OP pesticides have been carried out according to the multiclass multiresidue analysis method and acephate and methamidophos analysis method of Korea Food Code. In general the levels of OP pesticides found in the food samples were very low or not detected.

• The Journal of Korean Society for Radiation Therapy
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• v.29 no.1
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• pp.37-48
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• 2017

Purpose: The most basic conditions of radiation therapy is to prevent unnecessary exposure of normal tissue. The risk factors that are important o evaluate the dose emitted to the lung and heart from radiation therapy for breast cancer. Therefore, comparing the dose factors of a normal tissue according to the radion treatment position and Seeking an effective radiation treatment for breast cancer through the analysis of the correlation relationship. Materials and Methods: Computed tomography was conducted among 30 patients with left breast cancer in supine and prone position. Eclipse Treatment Planning System (Ver.11) was established by computerized treatment planning. Using the DVH compared the incident dose to normal tissue by position. Based on the result, Using the SPSS (ver.18) analyzed the dose in each normal tissue factors and Through the correlation analysis between variables, independent sample test examined the association. Finally The HI, CI value were compared Using the MIRADA RTx (ver. ad 1.6) in the supine, prone position Results: The results of computerized treatment planning of breast cancer in the supine position were V20, $16.5{\pm}2.6%$ and V30, $13.8{\pm}2.2%$ and Mean dose, $779.1{\pm}135.9cGy$ (absolute value). In the prone position it showed in the order $3.1{\pm}2.2%$, $1.8{\pm}1.7%$, $241.4{\pm}138.3cGy$. The prone position showed overall a lower dose. The average radiation dose 537.7 cGy less was exposured. In the case of heart, it showed that V30, $8.1{\pm}2.6%$ and $5.1{\pm}2.5%$, Mean dose, $594.9{\pm}225.3$ and $408{\pm}183.6cGy$ in the order supine, prone position. Results of statistical analysis, Cronbach's Alpha value of reliability analysis index is 0.563. The results of the correlation analysis between variables, position and dose factors of lung is about 0.89 or more, Which means a high correlation. For the heart, on the other hand it is less correlated to V30 (0.488), mean dose (0.418). Finally The results of independent samples t-test, position and dose factors of lung and heart were significantly higher in both the confidence level of 99 %. Conclusion: Radiation therapy is currently being developed state-of-the-art linear accelerator and a variety of treatment plan technology. The basic premise of the development think normal tissue protection around PTV. Of course, if you treat a breast cancer patient is in the prone position it take a lot of time and reproducibility of set-up problems. Nevertheless, As shown in the experiment results it is possible to reduce the dose to enter the lungs and the heart from the prone position. In conclusion, if a sufficient treatment time in the prone position and place correct confirmation will be more effective when the radiation treatment to patient.