• Journal of Korean Society of Environmental Engineers
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• v.28 no.11
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• pp.1198-1206
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• 2006

We have carried out highway traffic noise prediction and measurement for 10 sites with representative road shapes and structures. A road traffic noise prediction model(NIER('99)) has been developed for environmental impact assessment in Korea. With the fitted regression analysis, the distribution ratio($R^2$) and Pearson correction coefficient(r) was 92.4% and 0.96 in $1^{st}$ floor, 38.7% and 0.66 in $3^{rd}$ floor, 42% and 0.65 in $5^{th}$ floor, 7.5% and 0.27 in $7^{th}$ floor, 28.4% and 0.53 in 10th floor, 35.6% and 0.60 in $13^{th}$ floor, 52.7% and 0.73 in $15^{th}$ floor, respectively. The measured values of the noise level except the 1st floor did not show a good agreement with the predicted noise level in the NIER('99) formula. Also, the NIER('99) formula demonstrated that the measured values weren't reasonably close to the predicted values, indicating the validity and adequacy of the predicted models with the fitted vs residual analysis in the 95% of confidence interval and 95% of predict interval. Using the equal variation on the basis of the residual vs fitted value, there was the significant difference for variation between $3^{rd}$ floor and $15^{th}$ floor except $1^{st}$ floor. The results suggested that the NIER('99) model obtained by the results according to the apartment floor must be improved and developed on the road traffic noise.

• Restorative Dentistry and Endodontics
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• v.23 no.1
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• pp.1-19
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• 1998

After polymerizing composite resin with argon laser and visible light, four test, to be concretely, measurement of compressive strength using Instron testing machine, surface microhardness using Rockwell hardness tester, quantitative analysis of residual monomer using HPLC and analysis of degree of conversion using FTIR, were accomplished. Test groups were a sort of specimen with 3mm diameter, 4mm thickness for measuring compressive strength, two sort of specimen with 7mm diameter, 2mm and 3mm thickness for measuring surface microhardness, quantitative analysing of residual monomer after curing and measuring the degree of conversion, each were divided by six groups according to the condition of light exposure. In case of argon laser, in 1.0W and 0.5W output, the exposure time for specimen were 5 sec, 10 sec respectiyely. In case of visible light, the exposure time for specimen were 20 sec, 40 sec respectively. The test were accomplished and following results were obtained. 1. Compressive strength of composite resin was the highest in the group of 1 W output, exposing for 10 sec with argon laser, followed by the group of 0.5W, exposing for 10 sec with argon laser, the group of exposing for 40 sec with visible light. But there were statistically no significant difference between these three groups(p>0.05). 2. Surface microhardness of composite resin wasn't significantly affected by light curing conditions. 3. BIS-GMA within residual monomer was least detected in the group of exposing for 40 sec. TEGDMA was least detected in the group of 1 W output, exposing for 10 sec with argon laseboth 2mm and 3mm thickness specimen. 4. The degree of conversion of all groups in the 2mm thickness specimen were more than 50%, similar to each other but in the group of 1W, exposing 10 sec with argon laser the degree of conversion was highest in the 3mm thickness specimen. 5. Argon laser could make composite resin to has similar properties with 25% lesser exposure time than visible light.

• Journal of the Korean Recycled Construction Resources Institute
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• v.9 no.4
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• pp.405-412
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• 2021

The objective of this study is to investigate the environmental impact of fine dust generated at the construction waste intermediate treatment plants, and to propose engineering data and measures to suppress the generation of fine dust to cope with the expected strengthened environmental regulations of the government. The following study conclusions are drawn. 1) T he maximum concentration of fine dust in the workplace was measured as 160㎍/m³ from the crushing operation followed by the point of waste unloading, where focused suppression plan of the fine dust generation is needed in the future. 2) Fine dust concentrations of 113㎍/m³ in wet road conditions and 50㎍/m³ in dry conditions were measured, indicating that fine dust could be reduced by 50% with watering alone. 3) The effect of distancing from the dust source was studied. PM10 during operation of the workplace was measured as about 25㎍/m³ higher than those of the neighboring areas. Whereas there was no significant difference in case of PM2.5 between workplace and neighboring areas. 4) The measurement results of the heavy metal contents showed that these metals did not affect neighboring areas.

• Korean Journal of Construction Engineering and Management
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• v.25 no.2
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• pp.11-22
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• 2024

Power plant engineering industry obtains EPC plan project and delivers results about electricity, measurement, machinery, and piping and so on. Its works are taken by projects. Although power plant engineering composes 2~5% of whole EPC project cost, it's one of the fundamentals because it affects process after planning step a lot. However, domestic power plant engineering companies' project performance ability is insufficient and there's a need for systematic performance. Thus, this study defined related factors of successful performance and analyzed the priority among them through analytical hierarchy process. All respondents recognized experience, knowledge, and communication as important factors. Administrators considered knowledge, experience, and communication. But hands-on workers considered experience, knowledge, human resources. Those who have experience in oversea project considered process, experience, human resources. However those who don't have experience in oversea project considered knowledge, experience, and communication. Recognition of important factors varies by the position and work experience of members.

• Korean Journal of Digital Imaging in Medicine
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• v.16 no.1
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• pp.13-19
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• 2014

Purpose: FLAIR image is beneficial for the diagnosis of various bran diseases including ischemic CVS, brain tumors and infections. However the border between the legion of brain metastasis and surrounding edema may not be clear. Therefore, this study aims to investigate the practical benefits of delayed imaging by comparing the image from a patient with brain metastasis before a contrast enhancement and the image 10 minutes after a contrast enhancement. Materials and methods: Of the 92 people who underwent MRI brain metastases in suspected patients 13 people in three patients there is no video to target the 37 people confirmed cases, and motion artifacts brain metastases in our hospital June-December 2013, 18 people measurement position except for the three incorrect patient (male: 11 people, female: 7 people, average age: 60 years) in the target, test equipment, 3.0T MR System (ACHIEVA Release, Philips, I was 8ChannelSENSE Head Coil use Best, and the Netherlands). TR 11000 ms, TE 125 ms, TI2800 ms, Slice Thickness 5 mm, gap 5 mm, is a Slice number 21, the parameters of the 3D FFE, T2 FLAIR variable that was used to test, TR 8.1 ms, TE 3.7 ms, Slice number 240 I set to. The experiment was conducted by acquiring the FLAIR prior to contrast enhancement (heretofore referred to as Pre FLAIR), and acquiring the 3D FFE CE five minutes after the contrast enhancement, and recomposing the images in an axial plane of S/T 3mm, G 0mm (heretofore referred to as MPR TRA CE). Using the FLAIR 10 minutes after the contrast enhancement (heretofore referred to as Post FLAIR) and Pi-View, a retrospective study was conducted. Using MRIcro on the image of a patient confirmed for his diagnosis, the images before and after the contrast media, as well as the CNR and SNR of the MPR TRA CE images of the lesion and the site absent of lesion were compared and analyzed using a one-way analysis of variance. Results: CNR for Pre FLAIR and Post FLAIR were 34.35 and 60.13, respectively, with MPR TRA CE at 23.77 showing no significant difference (p<0.050). Post-experiment analysis shows a difference between Pre FLAIR and Post FLAIR in terms of CNR (p<0.050), but no difference in CNR between Post FLAIR and MPR TRA CE (p>0.050), indicating that the contrast media had an effect only on Pre FLAIR and Post FLAIR. The SNR for the normal site Pre FLAIR was 106.43, and for the lesion site 140.79. Post FLAIR for the normal site was 107.79, and for the lesion site 167.91. MPR TRA CE for the normal site was 140.23 and for the lesion site 183.19, showing significant difference (p<0.050), and post-experiment analysis shows that there was a difference in SNR only on the lesion sites for Pre FLAIR and Post FLAIR (p<0.050). There was no difference in SNR between the normal site and lesion site for Post FLAIR and MPR TRA CE, indicating no effect from the contrast media (p>0.050). Conclusions: This experiment shows that Post FLAIR has a higher contrast than Pre FLAIR, and a higher SNR for lesions, It was not not statistically significant and MPR TRA CE but CNR came out high. Inspection of post-contrast which is used in a high magnetic field is frequently used images of 3D T1 but, since the signal of the contrast medium and the blood flow is included, this method can be diagnostic accuracy is reduced, it is believed that when used in combination with Post FLAIR, and that can provide video information added to the diagnosis of brain metastases.

• Radiation Oncology Journal
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• v.19 no.2
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• pp.163-170
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• 2001

Purpose : The measurement of radiation survival using a clonogenic assay, the established standard, can be difficult and time consuming. In this study, We have used the MTT assay, based on the reduction of a tetrazolium salt to a purple formazan precipitate by living cells, as a substitution for clonogenic assay and have examined the optimal condition for performing this assay in determination of radiation sensitivity. Materials and Methods : Four human cancer cell lines - PCI-1, SNU-1066, NCI-H630 and RKO cells have been used. For each cell line, a clonogenic assay and a MTT assay using Premix WST-1 solution, which is one of the tetrazolium salts and does not require washing or solubilization of the precipitate were carried out after irradiation of 0, 2, 4, 6, 8, 10 Gy. For clonogenic assay, cells in $25\;cm^2$ flasks were irradiated after overnight incubation and the resultant colonies containing more than 50 cells were scored after culturing the cells for $10\~14$ days. For MTT assay, the relationship between absorbance and cell number, optimal seeding cell number, and optimal timing of assay was determined. Then, MTT assay was performed when the irradiated cells had regained exponential growth or when the non-irradiated cells had undergone four or more doubling times. Results : There was minimal variation in the values gained from these two methods with the standard deviation generally less than $5\%$, and there were no statistically significant differences between two methods according to t-test in low radiation dose (below 6 Gy). The regression analyses showed high linear correlation with the $R^2$ value of $0.975\~0.992$ between data from the two different methods. The optimal cell numbers for MTT assay were found to be dependent on plating efficiency of used cell line. Less than 300 cells/well were appropriate for cells with high plating efficiency (more than $30\%$). For cells with low plating efficiency (less than $30\%$), 500 cells/well or more were appropriate for assay. The optimal time for MTT assay was after 6 doubling times for the results compatible with those of clonogenic assay, at least after 4 doubling times was required for valid results. In consideration of practical limits of assay (12 days, in this study) cells with doubling time more than 3 days were inappropriate for application. Conclusion : In conclusion, it is found that MTT assay can successfully replace clonogenic assay of tested cancer cell lines after irradiation only if MTT assay was undertaken with optimal assay conditions that included plating efficiency of each cell line and doubling time at least.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.17 no.5 s.108
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• pp.461-475
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• 2006

In this paper, it is described about the tri-band mobile antenna system design to provide broadband multimedia and direct broadcasting services using goo-stationary Koreasat 3, simultaneously operated in Ka/K/Ku band. The radiating part of the antenna system with a fan beam characteristic in the elevation plane is composed of the quasi-offset dual shaped reflector and the tri-band feeder. The tri-band feeder is also composed of the Ka/K dual band feeder with the protruding dielectric rod, the circular polarizer, the ortho-mode transducer and the circular-polarized Ku band feed array. Especially, the Ka/K dual band circular polarizer was realized firstly using the comb-type structure. For fast satellite-tracking on the movement, the Ku band feed array has the structure of the $2{\times}2$ active phased array which can make electrical beams. And, the circular-polarized characteristic in the feed array was improved by $90^{\circ}$ rotating arrangement of four radiating elements polarized circularly by a $90^{\circ}$ hybrid coupler, respectively. Four beam forming channels to make electrical beams at Ku band are divided into the main beam channel and the tracking beam channel in the output, and noise temperature characteristics of each channel were analyzed on the basis of the contributions of internal sub_units. From the fabricated antenna system, the output power at $P_{1dBc}$ of Ka_Tx channel was measured more than 34.1 dBm and the measured noise figures of K/Ku_Rx channels were less than 2.4 dB and 1.5 dB, respectively, over the operating band. The radiation patterns with co- and cross-polarization in the tri-band were measured using a near-field measurement in the anechoic chamber. Especially, Ku radiation patterns were measured after correcting each initial phase of active channels with partial radiation patterns obtained from the independent excitation of each channel. The antenna gains measured in Ka/K/Ku band of the antenna system were more than 39.6 dBi, 37.5 dBi, 29.6 dBi, respectively. And, the antenna system showed good system performances such as Ka_Tx EIRP more than 43.7 dBW and K/Ku_Rx G/T more than 13.2 dB/K and 7.12 dB/K, respectively.

• Journal of radiological science and technology
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• v.31 no.3
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• pp.229-237
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• 2008

Purpose : For the number of microbes and the pollution level of bacteriology of IP Cassette and Table by laboratories, after identifying the bacteria before and after using alcohol and tissue including disinfectant and statistically testing, this research was intended to provide the basic data for the prevention and the right disinfection guideline for infection management of hospitals in diagnostic radiology. Subject and Method : The subject of this research was the general room of diagnostic radiology of a university hospital in Daejeon City. The research was conducted from Apr 5 to Apr 12, 2007. The number of microbes and the pollution level of bacteriology of IP Cassette and Table by laboratories were tested before and after using alcohol and tissue for disinfection including disinfectant. In order to collect specimens exactly, they were collected with the nurse who specialized in infection management of the hospital, and statistical processing was done with SPSS V13.0. To compare the results before and after using alcohol and tissue, T-test was implemented, and post-hoc test was conducted. Results : Bacteria were detected in 19 cases of 24 subjects(79.2%), however, they were not detected in 5 cases(20.8%). 7kinds of bacteria were detected as isolated bacteria, of which Methicillin Resistant coagulase-negative Staphylococci(MRCNS) were detected in 15 cases(62.5%), which was most, Methicillin Resistant Staphylococcus Aureus(MRSA) in 6 cases(16.7%), Enterococcus Faecium(EFM) in 5 cases(20.8%), Acinetobacter baumannii(ABA) in 2 cases(8.3%), and Bacillus sp, Coagulase-negative Staphylococci(CNS), and Enterococcus sp(ENT) in 1 case, respectively(4.2%). In all bacteria except ABA, Gram positive bacillia were detected in 30 cases(97%), and Gram negative bacilli were detected only in 1 case(3%). As for the kinds of bacteria and the number of groups before and after using 70% Alcohol by Groups, when the bacteria were identified after disinfecting IP Cassette and Table with 70% Alcohol, all the bacteria became extinct in both IP Cassette and Table Group(100%). As for the kinds and number of bacteria before and after using Tissue Cleaner by Groups, the bacteria in Tissue Cleaner Group became completely extinct only in 10 Groups(71.2%), and in 4 Groups, there was much decrease in bacteria, however, they were still detected. The extinction rate of all the bacteria was 91.5%. That is, though the other bacteria became extinct(100%), that of MRCNS bacteria was lowest(83.6%), followed by MRSA(95%). Conclusion : As a result of comparing the mean of the bacteria which were detected before and after using 70% Alcohol and Tissue Cleaner, there was statistically significant in the significant level of 5% in both of them.

• Journal of the Korean Society of Radiology
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• v.12 no.2
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• pp.201-208
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• 2018

The purpose of this study was to investigate the optimal flip angle by measuring the SNR and CNR according to the angle of changes of the MRI technique using the Image J program. A total of 30 normal volunteers were assessed by using a 1.5T magnetic resonance imaging system (Philips, Medical System, Achieva). For the MRI angiography, we set the region of interest in four regions and evaluated the SNR and CNR. The statistical significance of SNR and CNR was calculated by one-way ANOVA using quantitative analysis at five different positions. The Bonferroni method was used for post-hoc analyzes. Statistical significance was determined by using ANOVA analysis at p<0.05 and Bonferroni method was used as a post-hoc analysis. The results of this study, the measurement values of ACA(SNR:$876.59{\pm}14.22$, CNR:$1999.7{\pm}12.5$), PCA(SNR:$863.48{\pm}13.29$, CNR:$1870.18{\pm}12.56$), ICA(SNR:$1116.87{\pm}08.34$, CNR:$2979.37{\pm}14.69$) and MCA(SNR:$848.66{\pm}15.25$, CNR:$2199.25{\pm}13.48$) were obtained with the high signal intensity at $25^{\circ}$(p<0.05). The values of a1, a2, a3, p1, p2, p3, m1, m2 and m3 were also the same (p<0.05). Post-hoc analysis results, There was a statistically significant difference (p=0.000) between $10^{\circ}$, $15^{\circ}$, $20^{\circ}$ on the $25^{\circ}$ reference for the flip angle, but no significant results were obtained with $30^{\circ}$(p<0.05). In concision, because the signal intensity decreased at $30^{\circ}$, this study revealed that the optimal flip angles were $25^{\circ}$ in cerebrovascular MR angiography.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.24 no.2
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• pp.113-121
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• 2014

Objectives: This study is intended to seek credible and efficient measurements on airborne asbestos concentrations that allow immediate action by establishing complementary data through comparative analysis with existing PCM and KF-100 method real-time monitoring equipment in working areas in Seoul where asbestos-containing buildings are being demolished, including living environment surroundings. Materials: We measured airborne asbestos concentrations using PCM and KF-100 at research institutes, monitoring networks, subway stations and demolition sites of asbestos-containing buildings. Through this measurement data and KF-100 performance testing, we drew a conversion factor and applied it via KF-100. Finally we verified the relationship between PCM and KF-100 with statistical methods. Results: The airborne asbestos concentrations by PCM for the objects of study were less than the detection limit(7 fiber/$mm^2$) in three (20%) out of 15 samples. The highest concentration was 0.009 f/cc. The airborne asbestos concentrations by PCM in laboratories, monitoring networks, subway stations and demolition sites of asbestos-containing buildings were respectively $0.002{\pm}0.000$ f/cc, $0.004{\pm}0.001$ f/cc, $0.009{\pm}0.001$ f/cc, and $0.002{\pm}0.000$ f/cc. As a result of KF-100 performance testson rooftops, the conversion factor was 0.1958. Applying the conversion factor to KF-100 for laboratories, the airborne asbestos concentrations ratio of the two ways was nearly 1:1.5($R^2$=0.8852). Also,the airborne asbestos concentration ratio of the two ways was nearly 1:1($R^2$=0.9071) for monitoring networks, subway stations, and demolition sites of asbestos-containing buildings. As a result of independent sample t-tests, there was no distinction between airborne asbestos concentrations monitored in the two ways. Conclusions: In working areas where asbestos-containing buildings are being demolished, including living environment surroundings, quickly and accurately monitoring airborne asbestos scattered in the air around the working area is highly important. For this, we believea mutual interface of existing PCM and a real-time monitoring equipment method is possible.