• The Journal of Korean Society for Radiation Therapy
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• v.29 no.1
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• pp.77-84
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• 2017

Purpose: To evaluate the image quality improvement and dosimetric effects on virtual monochromatic images of a Dual Source-Dual Energy CT(DS-DECT) for radiotherapy planning. Materials and Methods: Dual energy(80/Sn 140 kVp) and single energy(120 kVp) scans were obtained with dual source CT scanner. Virtual monochromatic images were reconstructed at 40-140 keV for the catphan phantom study. The solid water-equivalent phantom for dosimetry performs an analytical calculation, which is implemented in TPS, of a 10 MV, $10{\times}10cm^2$ photon beam incident into the solid phantom with the existence of stainless steel. The dose profiles along the central axis at depths were discussed. The dosimetric consequences in computed treatment plans were evaluated based on polychromatic images at 120 kVp. Results: The magnitude of differences was large at lower monochromatic energy levels. The measurements at over 70 keV shows stable HU for polystyrene, acrylic. For CT to ED conversion curve, the shape of the curve at 120 kVp was close to that at 80 keV. 105 keV virtual monochromatic images were more successful than other energies at reducing streak artifacts, which some residual artifacts remained in the corrected image. The dose-calculation variations in radiotherapy treatment planning do not exceed ${\pm}0.7%$. Conclusion: Radiation doses with dual energy CT imaging can be lower than those with single energy CT imaging. The virtual monochromatic images were useful for the revision of CT number, which can be improved for target coverage and electron densities distribution.

• Analytical Science and Technology
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• v.36 no.6
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• pp.315-323
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• 2023

This study is to quantify α-quartz, cristobalite and kaolinite using by FTIR in respirable dust generated in the mining workplace. Various minerals in mines can interfere with peaks when quantifying respirable crystalline silica by FTIR. Therefore, for accurate quantification, it is necessary to remove interfering substances or correct the peaks that cause interference. To confirm the peaks occurring in α-quartz, cristobalite and kaolinite, each standard material was diluted with KBr and scanned in the range of 400 cm^-1 to 4000 cm^-1 using by FTIR. As a result of scanning the analytes, it was decided to use the peaks of 797.66 cm^-1 and 695.25 cm^-1 for α-quartz, 621.58 cm^-1 for cristobalite, and 3696.47 cm^-1 for kaolinite. When the above materials are mixed, interference occurs at the peak for quantification, which is corrected by the calculation formula. The analysis of the mixture of α-quartz and cristobalite shows the average bias (%) of 2.64 (corrected) at α-quartz (797.66 cm^-1), 5.61 (uncorrected) at α-quartz (695.25 cm^-1) and 1.51 (uncorrected) at cristobalite (621.58 cm^-1). The analysis of the mixture of α-quartz and kaolinite shows the average bias(%) of 1.79(corrected) at α-quartz (797.66 cm^-1), 3.92 (corrected) at α-quartz (695.25 cm^-1) and 2.58 (uncorrected) at kaolinite (3696.47 cm^-1). The analysis of the mixture of cristobalite and kaolinite shows the average bias (%) of 2.15 (corrected) at cristobalite (621.58 cm^-1), 4.32 (uncorrected) at kaolinite (3696.47 cm^-1). The analysis of the mixture of αquartz and cristobalite and kaolinite shows the average bias (%) of 1.93(corrected) at α-quartz (797.66 cm^-1), 6.47 (corrected) at α-quartz (695.25 cm^-1) and 1.77 (corrected) at cristobalite (621.58 cm^-1) and 2.61 (uncorrected) at kaolinite (3696.47 cm^-1). The experimental results showed that the deviation caused by peak interference by two or three substances could be corrected to less than 6 % of the average deviation. This study showed the possibility of correcting and quantifying when various interfering substances that are difficult to remove are mixed.

• Journal of Radiation Protection and Research
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• v.10 no.1
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• pp.50-63
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• 1985

A derivation of new release limit, named Derived Release Limit(DRL), into the atomsphere from a reference nuclear power plant has been performed on the basis of the new system of dose limitation recommended by the ICRP, instead of the (MPC)a limit which has been currently used until now as a general standard for radioactive effluents in Korea. In DRL Calculation, a Concentration Factor Method was applied, in which the concentrations of long-term routinely released radionuclides were in equilibrium with dose in environment under the steady state condition. The analytical model used in the exposure pathway analysis was the one which has been suggested by the USNRC and the exposure limits applied in this analysis were those recommended by the USEPA lately. In the exposure pathway analysis, all of the pathways are not considered and some may be excluded either because they are not applicable or their contribution to the exposure is insignificant compared with other pathways. In case, the environmental model developed in this study was applied to the Kori nuclear power plant as the reference power plant, the highest DRL value was calculated to be as $9.10{\times}10^6Ci/yr$ for Kr-85 in external whole body exposure from the semi-infinite radioactive cloud, while the lowest DRL value was observed 3.64Ci/yr for Co-60 in external whole body exposure from the contaminated ground, by the radioactive particulates. The most critical exposure pathway to an individual in the unrestricted area of interest (Kilchun-Ri, 1.3 km to the north of the release point) seems to be the exposure pathway from the contaminated ground and the most critical radionuclide in all pathways appears to be Co-60 in the same pathway. When comparing the actual release rate from KNU-l in 1982 with the DRL's obtained here the release of radionuclides from KNU-1 were much lower than the DRL's and it could be conclued that the exposure to an individual had been kept below the exposure limits recommended by the USEPA.

• 대한공업교육학회지
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• v.42 no.2
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• pp.67-88
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• 2017

The purpose of this research was educational needs of experts for revitalizing youth entrepreneurship education and creating effective conditions for such education. The subjects of the survey were chosen 100 teachers who had participated in entrepreneurship-related professional training for teachers were selected and surveyed. A total of 100 questionnaires were collected, of which 92 (92.00%) were used for the analysis. Eight were excluded as they were not properly answered. As for the used survey tool, a total of 8 areas and 30 items were derived from the review of the literature, and the validity of the contents was examined through expert meetings. The data were analyzed using the SPSS (ver. 20.0) statistical program. The analysis was conducted in terms of the required competency level, perceived competency level and educational needs. As for the used analytical methods, first, the averages of the required competency level and perceived competency level were calculated and the education needs were calculated using Borich's formula, and then the averages were compared through paired t-test. The results turned out to be statistically significant (p<.000). The details are as follows: As a result of the calculation of the educational needs the educational needs in all areas turned out to be very high with the average being 4.94 points, which indicates that the teachers strongly feel the need for educational strengthening in relation to entrepreneurship. These results show that all the educational conditions such as entrepreneurship-related curriculum, teacher professionalism, educational environment, educational support and the perception among school community members are insufficient in the current school settings. For the improvement of the current status, the education conditions in the following areas should be improved: the cooperation from school community members including principals, teacher support such as an exclusive responsibility teacher system, the development of an entrepreneurship curriculum, the securing of teacher professionalism through the implementation of the curriculum, teacher training support for the enhancement of their professionalism and the provision of educational environment and facilities. For enhancing the perception of parents and society regarding entrepreneurship, it is necessary to establish the precise concept of entrepreneurship and promote it based on such work.

• The Journal of Korean Society for Radiation Therapy
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• v.25 no.1
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• pp.15-24
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• 2013

Purpose: In Asan Medical Center, Two parallel opposite beams are employed for total body irradiation. Patients are required to be in supine position where two arms are attached to mid axillary line. Normally, physical compensators are required to compensate the large dose difference for different parts of body due to the different thicknesses compared to the umbilicus separation. There was the maximum dose difference up to 30% in lung and chest wall compared to the prescription dose. In order to resolve the dose discrepancy occurring on different body regions, the feasibility of using Fieid-in-Field Technique is investigated in this study. Materials and Methods: CT scan was performed to The RANDO Phantom with fabricated two arms and sent to Eclipse treatment planning system (version 10.0, Varian, USA). Conventional plan with physical lead compensator and new plan using Field-in-Field Technique were established on TPS. AAA (Anisotropic Analytical Algorithm) dose calculation algorithm was employed for two parallel opposite beams attenuation. Results: The dose difference between two methods was compared with the prescription dose. The dose distribution of chest and anterior chest wall uncovered by patient arms was 114~124% for physical lead compensator while Field-in-Field Technique gave 106~107% of the dose distribution. In-vivo dosimetry result using TLD showed that the dose distribution to the same region was 110~117% for conventional physical compensator and 104~107% for Field-in-Field Technique. Conclusion: In this study, the feasibility of using FIF technique has been investigated with fabricated arms attached Rando phantom. The dose difference was up to 17% due to the attached arms. It is shown that the dose homogeneity is within ${\pm}10%$ with the CT based 3-dimensional 4 step FIF technique. The in-vivo dosimetry result using TLD was showed that 95~107% dose distribution compared to prescription dose. It is considered that CT based 3-dimensional Field-in-Field Technique for the total body irradiation gives much homogeneous dose distribution for different body parts than the conventional physical compensator method and might be useful to evaluate the dose on each part of patient body.

• Fire Science and Engineering
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• v.17 no.1
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• pp.8-20
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• 2003

Natural gas has been supplied through underground pipelines and valve stations as a new city gas in Seoul. In contrast to its handiness the natural gas has very substantial hazards due to fires and explosions occurring from careless treatments or malfunctions of the transporting system. The main objectives of this study are to identify major hazards and to perform risk assessments after assessing reliabilities of the composing units in dealing with typical pipeline networks. there-fore two method, fault tree analysis ;1nd event tree analysis, are used here. Random valve stations are selected and considered its situation in location. The value of small leakage, large rupture, and no supply of liquefied natural gas is estimated as that of top event. By this calculation the values of small leakage are 3.29 in I)C valve station, 1.41 in DS valve station, those of large rup-lure are $1.90Times10_{-2}$ in DC valve station, $2.32$\times$10^{-2}$ in DS valve station, and those of no supply of LNG to civil gas company are $2.33$\times$10 ^{-2}$ , $2.89$\times$10^{-2}$ in each valve station. And through minimal cut set we can find the parts that is important and should be more important in overall system. In DC valve station one line must be added between basic event 26,27 because the potential hazard of these parts is the highest value. If it is added the failure rate of no supply of LNG is reduced to one fourth. In DS valve station the failure rate of basic event 4 is 92eye of no supply of LNG. Therefore if the portion of this part is reduced (one line added) the total failure rate can be decreased to one tenth. This analytical study on the risk assessment is very useful to prepare emergency actions or procedures in case of gas accidents around underground pipeline networks and to establish a resolute gas safety management system for loss prevention in Seoul metropolitan area.

• Journal of Korean Public Health Nursing
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• v.4 no.1
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• pp.57-74
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• 1990

As the whole world took on the tendency to be highly industrialized, it became necessary for each field of occupation to require professional man power. Especially, since the World War n, the participation of woman power in economic activities has been continually increasing. In our country also, because of the rapid economic growth, change in the way of thinking of women as well as their participation in economic activities are increasing. Thus, woman power is being utilized in various occupational fields from simple physical labor to those that require high-professional skill. Also, continued economic development policies, by setting the establishment of welfare society as the ideology to be fulfilled, brought expansion of medical facilities in the field of public health and increase in man power in that field. As for the nursing specialists, more than 6000 have been being produced per year and as of the end of 1988, the total number of nursing specialists, reached 123, 115. Therefore, this study is done to recognize the professional knowledge and ability of nursing specialists, who take up $40\%$ of the total public-health related man power in our country, through evaluating their working environment and their disposition of character. This study, which was done from September 18th to September 30th 1989, took on the method of using formed questionnaires that had been amended and supplemented during two preparatory investigations, 322 of such questionnaires were used as an analytical material. In the formation of questionnaires, 12 questions were related to the working environment, and 26 in fortotal were related to the disposition of character, 5 for wise-disposition, 11 for activedisposition and 10 for open-disposition. The measuring method, which used 5-point-standard, allowed 5 points for affirmative recognition of the working environment, also 5 points for showing wise, active and open disposition of character and only point in opposite cases. Collected materials were analyzed, through an electronic calculation, into the average value, the standard deflection percentage, pearson corelative number and stepwise multiple regression. Summarizing the results from this study is as follows: 1. It was shown that the nursing specialists with the average of 3.07 have affirmative recognition of their working environment. The questions which drew most affirmative reaction were those concerning finance-management system such as hand, the questions that received negative reaction were those concerning communication method with the average of 2.49. Such reaction seems to have resulted from the cramming regulation by the superior authorities. Concerning the recognition of working environment in relation to employment conditions, more affirmative recognition is shown with the average of 3.14. at hospitals where injection job is not performed. The nursing specialists working at regular hospitals show more affirmative recognition than those at general hospitals, the averages being respectiely 3.16 and 3.03. 2. As for the disposition of character of the nursing specialists, active-disposition was highest with the average of 3.38, next was wise-disposition with 3.20 and the lowest was open-diposition with 2.98. Variable-wise disposition of character shows that wise-disposition and academic background are beneficially correlated by 0.12. Ative-disposition and open-disposition show correlation to the office term by respectively 0.16 and 0.21. In other words. better academic background leads to higher wise-disposition and more - experience results in higher active and open disposition. Also, the class that performs the injection job, in relation to the working environment, might cause change in the self-conceit that identify those in that class with the nurses; however, as far as professional judgment and action, in dealing with nursing job, being wise, active and open is concerned, not much effect is made. 3. The relation between the recognition of the working environment and the disposition of character is that more afirmative recognition- a nursing specialist has about her working environment, the higher the active-disposition becomes by 0.13. The degrees of the relation between recongnition of environment and wise and open dispositions show respectively 0.06 and -0.06 and -0.06. That is to say that when having more affirmative recognition of the working environment, a nursing specialist shows wise but closed disposition of character. This, howerver, didn't mean much statistically. When observing the results mentioned above, it is conspicuous that the nursing specialists, working as substitutes for the nurse at medical institutions of various sizes, get the feeling of being somewhat equal to the nurses and to some extent, fulfill their desire to accomplish their ego; however, as far as professional ability expansion if concerned. they lack wise and open dispositions. Therefore, considiering upon the results of this study, in medical institutions where the work of nursing specialists is regaded equal to that of the nurses, as a medical member who deals with human lives, it is desirable to make the nursing specialists work under the supervision of the nurses and to offer them continuous education to strengthen and improve their natural dispositions.

• Progress in Medical Physics
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• v.25 no.4
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• pp.210-217
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• 2014

This study investigated the dosimetric effects of different dose calculation algorithm for lung stereotactic ablative radiotherapy (SABR) using flattening filter-free (FFF) beams. A total of 10 patients with lung cancer who were treated with SABR were evaluated. All treatment plans were created using an Acuros XB (AXB) of an Eclipse treatment planning system. An additional plans for comparison of different alagorithm recalcuated with anisotropic analytic algorithm (AAA) algorithm. To address both algorithms, the cumulative dose-volume histogram (DVH) was analyzed for the planning target volume (PTV) and organs at risk (OARs). Technical parameters, such as the computation times and total monitor units (MUs), were also evaluated. A comparison analysis of DVHs from these plans revealed the PTV for AXB estimated a higher maximum dose (5.2%) and lower minimum dose (4.2%) than that of the AAA. The highest dose difference observed 7.06% for the PTV $V_{105%}$. The maximum dose to the lung was also slightly larger in the AXB plans. The percentate volumes of the ipsilateral lung ($V_5$, $V_{10}$, $V_{20}$) receiving 5, 10, and 20 Gy were also larger in AXB plans than for AAA plans. However, these parameters were comparable between both AAA and AXB plans for the contralateral lung. The differences of the maximum dose for the spinal cord and heart were also small. The computation time of AXB plans was 13.7% shorter than that of AAA plans. The average MUs were 3.47% larger for AXB plans than for AAA plans. The results of this study suggest that AXB algorithm can provide advantages such as accurate dose calculations and reduced computation time in lung SABR plan using FFF beams, especially for volumetric modulated arc therapy technique.

• Journal of the Korean Society of Marine Environment & Safety
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• v.29 no.4
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• pp.363-371
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• 2023

To construct a ship, blocks of various sizes must be moved and erected . In this process, lugs are used such that they match the block fastening method and various functions suitable for the characteristics of each shipyard facility. The sizes and shapes of the lugs vary depending on the weight and shape of the block structures. The structure is reinforced by welding the doubling pads to compensate for insufficient rigidity around the holes where the shackle is fastened. As for the method of designing lugs according to lifting loading conditions, a simple calculation based on the beam theory and structural analysis using numerical modeling are performed. In the case of the analytical method, a standardized evaluation method must be established because results may differ depending on the type of element and modeling method. The application of this ambiguous methodology may cause serious safety problems during the process of moving and turning-over blocks. In this study , the effects of various parameters are compared and analyzed through numerical structural analysis to determine the modeling conditions and evaluation method that can evaluate the actual structural response of the lug. The modeling technique that represents the plate part and weld bead around the lug hole provides the most realistic behavior results. The modeling results with the same conditions as those of the actual lug where only the weld bead is connected to the main body of the lug, showed a lower ulimated strength compared with the results obtained by applying the MPC load. The two-dimensional shell element is applied to reduce the modeling and analysis time, and a safety working load was verified to be predicted by reducing the thickness of the doubling pad by 85%. The results of the effects of various parameters reviewed in the study are expected to be used as good reference data for the lug design and safe working load prediction.