• Proceedings of the Korea Concrete Institute Conference
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• 1996.10a
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• pp.175-182
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• 1996

This paper deals with the properties of water permeability and porosity of cement mortar substrate coated with siliceous slurry coating under the exposure environment. Conditions of exposure enviornment are four kinds of in constant temperature water and humidity box, in indoor and outdoor exposure. Coated mortar substrate was expected continually increase in water and humidity condition, but was not in dry condition. Watertightness effect of siliceous coating was better in the condition of humidity then the dry condition, and the pore volume was decreased in that condition.

• Journal of the Korean Society of Radiology
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• v.14 no.4
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• pp.353-360
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• 2020

This research aims at suggesting exposure condition that shows maintaining the value of the physical image quality factor by decreasing tube voltage and tube current from the standard exposure condition(80 kV, 7 mA) of a CBCT apparatus. To measure the value of the physical image quality factor, modular transfer function(MTF) was analyzed and dose-area product(DAP) was used for the measurement of exposure dose. CBCT images of a Sedentex IQ phantom were obtained under 15 exposure conditions of different combination of tube voltage(80, 78, 76 kV) and tube current(7, 6, 5, 4, 3 mA) and MTF 10 was calculated under each exposure conditions. There were no significant differences in MTF 10 under 80 kV-6 mA, 80 kV-5 mA exposure conditions in comparison with standard exposure condition. Based on the results of this research, 80 kV-5 mA condition are expected to be able to reduce exposure dose with maintaining the value of the physical image quality factor of the standard exposure condition.

• Journal of Korean Academy of Oral and Maxillofacial Radiology
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• v.22 no.2
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• pp.293-303
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• 1992

Generally the patient's absorb dose and readability of radiograms are affected by the exposure time and kVp of which are related with the radiographic density and contrast The investigator carried studies to know the adequate level of exposure time and kVp to obtain the better readability of radiograms. In these studies dried human mandible with selfcuring acrylic resins attached with aluminum step wedge was used and readability of radiograms were compared with each other by videodensitometry among various combination sets of the exposure time, such as 5, 6, 8, 12, 15, 19, 24, 30, 38, 48 and 60, and varing level of kVp, such as 60, 65, 70, 80 and 90 respectively. The obtained results were as follows: 1. As exposure time and kVp were increased, radiographic density of radiograms was increased. 2. The subject contrast was increased where aluminum step wedge was thin and reduced in the reversed condition. At the thin aluminum step wedge, subject contrast was increased at the condition of lower kilovoltage than that of higher kilovoltage. 3. In the case of non-constant radiographic density, the radiographic contrast was reduced with the increment kilovoltage. The radiographic contrast was increased in the lower kilovoltage with the longer exposure time and the higher kilovoltage with the shorter exposure time. 4. At the condition of short exposure time, better readability of each reading item was obtained with the increment of the kilovoltage but at the opposite condition increasing exposure time worsened readability of radiograms. Since X-ray machine in the current dental clinics is fixed between the range of 60-70kVp and 10mA, good radiograms can be obtained by varied exposure time. But according to the conclusion of these studies, better radiograms can be obtained by using filtered high kVp and then the absorb dose to patient and exposure time can be reduced.

• Journal of the Korean Society of Radiology
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• v.10 no.2
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• pp.109-115
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• 2016

Despite of increasing the use of the digital imaging device in the radiology area, the setting on the optimal irradiation conditions are insufficient. In this study, the exposure dose and image quality by exposure condition of digital radiography device were compared. The exposure doses were obtained by adjusting the exposure condition as 5 steps respectively based on the exposure conditions that are currently used of CR and DR radiography devices. The acquired image has been assessed by 20 medical image professors using the assessment method of the Japanese Society for Tuberculosis Prevent. As a result, in the case of the CR system, the better image quality was obtained in the condition of 120 kVp and 1.5 mAs~2.4 mAs (quality score 91~95.5 points) than standard exposure condition(110 kVp, 3.2 mAs, 86 points). And exposure dose was evaluated as low with $61.3{\sim}98.4{\mu}Gy$ than standard condition($105.11{\mu}Gy$). In DR system, however, the image quality score was higher as 97~98.6 points in the lower tube voltage range (112 kVp, 2.4~3.2 mAs) condition than the standard exposure condition (125 kVp, 3.2 mAs, 91 points). In addition, the exposure dose was $61.5-77.2{\mu}Gy$ lower than standard condition($93{\mu}Gy$). In addition, the exposure dose was low as $61.5-77.2{\mu}Gy$ than standard condition($93{\mu}Gy$). With the results of this study, we confirmed that it is possible to reduce the patient exposure dose with the same image quality by adjusting the optimal exposure condition of digital device.

• Journal of Environmental Health Sciences
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• v.44 no.5
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• pp.460-467
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• 2018

Objectives: The objectives of this study are to estimate the inhalation exposure level of benzene for workers using Tier 1 exposure models ECETOC TRA (European Center for Ecotoxicology and Toxicology of Chemicals Target Risk Assessment) and Stoffenmanager, and to investigate their reliability for exposure assessment in K-REACH. Methods: Two exposure scenarios, 'manufacture of benzene' and 'use as solvents,' were developed for assessment of workers' exposure to benzene. The Process Category (PROC) for ECETOC TRA was collected from the European Chemical Agency (ECHA) registration dossier, and the Activity for Stoffenmanager was converted from PROC using translation of exposure models (TREXMO). The information related to exposure, such as working duration, Respiratory Protective Equipment (RPE), Local Exhaust Ventilation (LEV), and Risk Management Measure (RMM) were classified into high, medium, and low exposure conditions. The risk was determined by the ratio of the estimated exposure and occupational exposure limits of benzene. Results: Under high exposure conditions, the worker exposure level calculated from all PROCs and Activities exceeded the risk level, with the exception of PROC 1 and Activity 1. In the medium exposure condition, PROC 8a, 8b, and 9 and Activity 3, 7, and 8 all exceeded the risk, whereas in the low condition, all PROCs and Activities were determined to be safe. As a result, action corresponding with the low exposure condition is required to reduce the risk of exposure among workers in workplaces where benzene is manufactured or used as a solvent. In addition, the predicted exposure levels derived from the exposure models were lower than measured levels. The exposure levels estimated from Stoffenmanager were more conservative than those from ECETOC TRA. Conclusions: This study demonstrates the feasibility of exposure models for exposure assessment through the example of occupational inhalation exposure assessment for benzene. For more active utilization of exposure models in K-REACH, the exact application of collected information and accurate interpretation of obtained results are necessary.

• Environmental Analysis Health and Toxicology
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• v.22 no.3
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• pp.235-245
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• 2007

Toxicity of nonlyphenol (NP) one of EDCs was studied with focus on reproduction of the crucian carp, Carassius auratus. Fishes were cultured under control and nonylphnol exposure conditions for 32 weeks. Experimental group was composed of total of 4 groups, 1 control condition and 3 nonylphenol exposure condition ($18\;{\mu}g\;NP\;L^{-1},\;37\;{\mu}g\;NP\;L^{-1}\;and\;83\;{\mu}g\;NP\;L^{-1}$). Survival rate was found to be similar in control and $18\;{\mu};NP\;L^{-1}$. However, it is lower In the $37\;{\mu};NP\;L^{-1}$ and $83\;{\mu};NP\;L^{-1}$ in comparison to the control group. Deformation of gonads was the highest in the exposure condition of $18{\mu};NP\;L^{-1}$ with the female illustrating higher ratio than the male. GSI was not much different in the male but in the female, NP exposure group illustrated lower value compared to the control group. HSI and GI did not illustrate any clear differences between the control and exposure group for both male and female. Intersex was 0% in the wild group, 4.16% in the laboratory control group, and 25.67% in the NP exposure condition with female illustrating higher compared to male. Concentration of blood vitellogenin in female illustrated no clear differences between the control and NP exposure group. However, in the male, it was higher in the NP exposure group in comparison to the control group, and illustrated higher values of vitellogenin compared to the figures found in the female of same con-centration condition.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.5 no.11
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• pp.2160-2174
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• 2011

In this paper, a new technique for color reproduction based on color variation characteristics of digital camera under a dim light condition is proposed. Generally, photographers should adjust a camera exposure properly for obtaining an image with real color tone of subjects. Thus, in case of taking a picture under a dim light condition, the exposure time of a camera has to be relatively longer than the one under a bright light condition. Although images with real color tone of the subject are obtained, the images may get blurred due to the shaky hands of photographer holding the camera. In order to avoid the blur effect, an input image is captured from a camera set as a short exposure time under a dim light condition. Then we propose a method to reproduce color tone of the dim input image. To this end, color variation characteristics which represent color variations of a digital camera are first extracted by analyzing the Macbeth color checker images taken under various exposure values. Then, a color reproduction is performed by an estimation based on the color variation characteristics. Experimental results have shown that the proposed method has achieved better performance of color reproduction, compared with existing methods.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.22 no.3
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• pp.264-274
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• 2012

Evaluation on the environmental noise is carried out by surveying subjective response of residents with physical measurement of noise during long period in field. Particularly field survey is used to make regulations from the analysis on how many people are annoyed for specific noise level, and laboratory test used to analyze the relationship between physical parameters of noise and subjective responses. In the laboratory controlling the variables is easy but the results could be biased because the condition in room would be different with field. Most of all noise exposure time is considered to be different with real situation, and this study aimed to evaluate the subjective response by exposure time of transportation noise, by applying three kinds of variable how much they give effects on the annoyance as the exposure time is operating condition, windows type and sound level. As a result there was somewhat difference between operating type and annoyance, which is caused by the sound characteristics operated in different condition. However the window type didn't give much effect to the annoyance as much as sound type. This means that the subjective response could give similar result by exposure time even for different window types. Most of all, the main factor affecting subjective response is considered to be the sound level and the exposure time.

• Journal of radiological science and technology
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• v.21 no.2
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• pp.19-25
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• 1998

By analyzing each part of expsure condition and the status of an entrance dose which is exposed to patients, this study reached the following conclusion. Since there is no standard in setting up an exposure condition, the technology practiced in each facility varies tremendously, and the entrance dose increased especially due to the improper selection of screen and grid and the shortage of a total amount of filtration in leaching the standard filtration amount. Entrance dose was, generally, turned out to be $2{\sim}3$ times as much as that of advanced countries, and there was big difference between facilities ; approximately 52 times inlateral of cervical vertebrae, 35 times in A-P of femur, 33 times in chest A-P, and 11 times in lumber A-P. Therefore, to minimize the entrance dose of a patient with thegreatest amount of image information, acquirement of technological know-how necessary for standardization of exposure condition for each part can be an important research task.

• Journal of Aerospace System Engineering
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• v.2 no.2
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• pp.42-45
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• 2008

Under the non-operating exposure condition in the hot area, the T-50 cockpit temperature is expected over the requirement according to T-50 environmental criteria. So it is necessary to protect the cockpit from the high temperature condition during the non-operating exposure because the high temperature of the cockpit may result in the cockpit equipment malfunction. In this study, the transparency coating is selected as the method for protecting the cockpit from the high temperature exposure and analyzed the effect on the cockpit heat load attenuation. Some kinds of cockpit coating were reviewed and selected and the analysis was performed about the effect before and after coating application under 1% hot day condition based on the T-50 FSD hot soaking test data. The result of analysis show transparency coating is so effective to attenuate the heat load of T-50 cockpit.