• Journal of the Korean Society for Precision Engineering
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• v.18 no.9
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• pp.110-121
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• 2001

During hot pipe bending using induction heating, the wall of bending outside is thinned by tensile stress. In design requirement, the reduction of wall thickness is not allowed to exceed 12.5%. So in this study, two methods of bending, one is loading of reverse moment and the other is loading of temperature gradient, have been investigated to design pipe bending process that satisfy design requirements. For this purpose, finite element analysis with a bending radius 2Do(outer diameter of pipe) has been performed to calculate proper reverse moment and temperature gradient to be applied. Induction heating process has been analyzed to estimate influence of heating process parameters on heating characteristic by finite difference method. Then pipe bending experiments have been performed for verification of finite element and finite difference analysis results. Experimental results are in good agreement with the results of simulations.

• Korea Trade Review
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• v.46 no.1
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• pp.135-154
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• 2021

This study aims to investigate the difference in the perception of shippers on the quality of air freight service between air express and air freight forwarders. This study suggests hypothesis verification and implications on importance-performance between two groups of air express and air freight forwarders. In this study, we find that important variables through paired t-test and importance-performance analysis. As a result of paired t-test, there was a difference in the use variables of the document work variables through computerization in the importance area. In the satisfaction area, there was a difference between the groups in the response to customer request and the response to accidents. The variables that need to improve the focus derived from the importance-performance analysis are document work through computer and response to accidents. It is necessary to observe and manage the response of shippers continuously by holding various transportation schedules in the schedule area, possibility of adjustment of transportation schedule, regular freight and schedule provision.

• Journal of the Korean School Mathematics Society
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• v.4 no.2
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• pp.103-113
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• 2001

The teaching-learning method utilizing Web makes it possible for the students take the initiative in any field and offers the teaching strategy, methodology and teaching-learning materials suitable for students' ability and standard. The purpose of this study is to investigate the characteristics of WBI in mathematics class for the effective teaching and learning focusing on the unit 'Function' in the 1st grade of middle school and verify its effectiveness by developing the WBI programs which can progress learning achievement and applying them to math class. Two hypotheses were established for this study. Hypothesis 1 : There will be meaningful difference between the group that studies under WBI and the one that doesn't, Hypothesis 2 : There will be meaningful difference in the attitude and interest toward learning between the group that studies under WBI and the one that doesn't. In order to find out the result, I have made a comparative analysis through t-verification on the object of two classes of the 1st grade in P middle school that I have been working for. The result shows that the class utilizing WBI is more effective than the traditional lecture-oriented class since there is a meaningful difference between the control group and experimental one and also that the class based on WEB has a great influence on students' interest and positive attitude toward math class.

• Journal of the Society of Disaster Information
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• v.16 no.1
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• pp.163-177
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• 2020

Purpose: While it is very important to maintain facilities recently, the introduction and its application of high technology in the facility maintenance industry has increased. It is necessary for high technology to secure reliability through the verification and certification system of diagnostic equipment to have an effective impact in the field, but there is difference between the industry's perspective and realistic level of technology apart from social demand for the system of the system. This paper dealt with the introduction of a verification and certification system for rational facility diagnostic equipment with the opinion survey on managers about the current situation. Method: Survey is carried out targeting managers in the maintenance and construction regarding the necessity and urgency of introducing a verification and certification system to promote the introduction and its application of high technology of diagnostic equipment and facility inspection. Also, the introduction to a verification and certification system was reviewed for advanced facility diagnostic equipment through foreign research about similar systems and comparative analysis of similar systems related to the certification of 21 domestic equipment. Result: It showed that, regarding the application of high technology, it is necessary for most managers to introduce high technology such as drones, robots, etc., in the maintenance industry, and when high technology is introduced, it will have a considerable effect in the field. On the other hand, the current technology level in Korea is relatively low, so it turned out to take a certain amount of time for the application of technology. Also, it was found that the management of reliable facility diagnostic equipment will be possible through the introduction of the verification and certification system for facility diagnosis equipment. Meanwhile, the survey is conducted on similar systems about foreign and domestic diagnosis and measuring equipment, etc., but there is no system to verify and certify equipment applied with high technology directly to facility diagnosis maintenance. However, because Japan has a system of verifying the performance of diagnostic equipment and South Korea has 21 similar inspection and diagnostic equipment certification systems among 186 certification systems, it is considered to be possible to design systems which utilize them. Conclusion: According to the managers' opinion, it seems that the introduction of the system supporting the application of 4th industrial technology for the equipment and the use of the equipment with high reliability has sufficient validity. However, because our high technology level is undervalued compared to the urgency, the system for checking high technology facilities and certifying diagnostic equipment should be to be implemented in form of escalation considering technical use and verification level. Apart from the introduction of the verification and certification system, it is necessary for special investment, support and efforts to promote advanced facility diagnostic equipment.

• Journal of Korean society of Dental Hygiene
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• v.8 no.3
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• pp.115-126
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• 2008

Purpose : The research which sees width for a wide gain and loss is about brush qualitative management of the child about dental hygiene of the child is investigated the brush qualitative actual condition. Methods : The data which is collected used SPSS(Statistical Package for the Social Science) WIN 11.5 programs and analyzed, a frequency and a percentage with analytical technique, in order to grasp the general quality of the investigation object person produced to examine is about the brush quality control actual condition of the children opinion t-test (verification) frequency analyses and $x^2$(Chi-square) verifications, executed. Result : The followings are the findings of this research. First, the children about the reason which wipes this 83.4% the thing protection dental caries answer back, followed in grade and considers the difference which was visible(p<0.001). Second, wipes whether to experience is educated answer back 83.0% was educated, followed in sex and considers the difference which was visible(p<0.05). Third, when 1 time is brush quality of the children doing, in grade and the time when becomes disturbance was, most between 2~3 minutes followed considers the difference which was visible(p<0.01). Fourth, when 1 time is brush quality of the children doing, in grade and the time when becomes disturbance was, most between 2~3 minutes followed considers the difference which was visible(p<0.01). Fifth, when 1 time is brush quality of the children doing, in grade and the time when becomes disturbance was, most between 2~3 minutes followed considers the difference which was visible(p<0.05, p<.001). Sixth, Use duration of the toothbrush the child of most was 3~6 months, according to grade and sex was visible the difference which considers. Conclusion : Are oral healthily of the children is the knowledge which relates with a brush quality and practical degree important. Therefore this there must be dental health education program development will be able to improve, means must reflect the dental health education at the time of.

• Journal of Radiation Protection and Research
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• v.36 no.4
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• pp.183-189
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• 2011

To quantitatively evaluate how setup errors in conjunction with dose gradients contribute to the error in IMRT dose quality assurance (DQA) measurements. The control group consisted of 5 DQA plans of which all individual field dose differences were less than ${\pm}5%$. On the contrary, the examination group was composed of 16 DQA plans where any individual field dose difference was larger than ${\pm}10%$ even though their total dose differences were less than ${\pm}5%$. The difference in 3D dose gradients between the two groups was estimated in a cube of $6{\times}6{\times}6\;mm^3$ centered at the verification point. Under the assumption that setup errors existed during the DQA measurements of the examination group, a three dimensional offset point inside the cube was sought out, where the individual field dose difference was minimized. The average dose gradients of the control group along the x, y, and z axes were 0.21, 0.20, and 0.15 $cGy{\cdot}mm^{-1}$, respectively, while those of the examination group were 0.64, 0.48, and 0.28 $cGy{\cdot}mm^{-1}$, respectively. All 16 plans of the examination group had their own 3D offset points in the cube. The individual field dose differences recalculated at the offset points were mostly diminished and thus the average values of total and individual field dose differences were reduced from 3.1% to 2.2% and 15.4% to 2.2%, respectively. The offset distribution turned out to be random in the 3D coordinate. This study provided the quantitative data that support the large individual field dose difference mainly stems from possible geometric errors (e.g., random setup errors) under the influence of steep dose gradients of IMRT field.

• Culinary science and hospitality research
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• v.14 no.2
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• pp.61-72
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• 2008

The purpose of this study was to analyze the difference in preference and property of native local foods among students living in Busan. It concentrated on the students who were majored in food service in five universities in Busan. From September 1st to 30th, 2007, 300 copies of questionnaire were distributed and 260 returned were included in the statistics. The statistics was conducted by frequency analysis, T-test(average deviation verification), technical analysis and one way ANOVA for an accurate result of the study. As a result, it was found that Gayamilmyeon(M=4.42) showed the most preference for 25 native local foods of Busan(sansungmakgeoli, dongraepajeon, steamed carp, catfish soup, corbicula soup, roasted eel, gijang raw hairtail, dongrae mugwort cake, sansung roasted goat, gijangkkomjangeo, steamed frogfish, duck dish, guponoodles, gayamilmyeon, sliced raw fish, molsim hot-pepper fish stew, hairtail stew, anchovy stew, miyeoksulchi, gompi salted dish, salted raw anchovy dish, roasted kkomjaneo, salted sliced persimmon dish, salted bean leave dish, kkasiri soup). On the other hand, it was found that Miyeoksulchi(M=2.66) showed the least preference among them. As a result of the analysis of the difference in demographic characteristics and property of native local foods, it was presented that there was no difference in the statistical analysis by sex but significant difference in taste, quantity, service, price, freshness, sanitation, packing condition and originality, etc by age, department, academic year, type of residence, family member, living period in Busan and monthly spending. It was considered to conduct a more in-depth study to promote native local foods and interest in the food of Busan in university students.

• Journal of Environmental Health Sciences
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• v.47 no.1
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• pp.64-77
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• 2021

Objective: Biological monitoring of trace elements in human blood samples has become an important indicator of the health environment. The purpose of this study was to detect and evaluate multiple metal items in blood samples based on ICP-MS, to perform comparative evaluation with the existing analysis method, and to develop and verify a new method. Methods: 100 μL of whole blood from 80 healthy subjects was used to analyze ten metals (Sb, tAs, Cd, Pb, Mn, Hg, Mo, Ni, Se, Tl) using ICP-MS. Verification of the analysis method included calculation of linearity, accuracy, precision and detection limits. In addition, a comparative test with the conventional graphite furnace atomic absorption spectroscopy (GF-AAS) method was performed. In the case of Pb, Cd, and Hg in whole blood, cross-analysis between Pb, Cd, and Hg analysis methods was performed to confirm the difference between the existing method and the new method (ICP-MS). Results: The coefficient of determination (R2) was 0.999 or higher in seven items and 0.995 or higher in three items. The Pb result showed that Pearson's correlation coefficient was very high at 0.983, and the intraclass correlation coefficient was 0.966. The Cd result showed that Pearson's correlation coefficient was 0.917 between the existing method and the new analysis concentration value. Its intraclass correlation coefficient was 0.960, and there was no significant difference between the two groups. Hg had a low correlation at 0.687, and the intraclass correlation coefficient was 0.761, which was lower than that of Pb and Cd. The intra-day and inter-day accuracy of Pd and Cd were satisfactory, but Hg did not meet the criteria for both accuracy and precision when compared with the conventional analysis method. Conclusion: This study can be meaningful in that it proposes a more efficient and feasible analysis method by verifying a blood heavy metal concentration experiment using multiple simultaneous analyses. All samples were processed and analyzed using the new ICP-MS. It was confirmed that the agreement between the two methods was very high, with the agreement between the current and new methods being 0.769 to 0.998. This study proposes an efficient simultaneous methodology capable of analyzing multiple elements with small samples. In the future, studies of various applications and the reliability of ICP-MS analysis methods are required, and research on the verification of accurate, precise, and continuous analysis methods is required.

• Progress in Medical Physics
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• v.29 no.3
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• pp.92-100
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• 2018

The manufacturer of a linear accelerator (LINAC) has reported that the target melting phenomenon could be caused by a non-recommended output setting and the excessive use of monitor unit (MU) with intensity-modulated radiation therapy (IMRT). Due to these reasons, we observed an unexpected beam interruption during the treatment of a patient in our institution. The target status was inspected and a replacement of the target was determined. After the target replacement, the beam profile was adjusted to the machine commissioning beam data, and the absolute doses-to-water for 6 MV and 10 MV photon beams were calibrated according to American Association of Physicists in Medicine (AAPM) Task Group (TG)-51 protocol. To verify the beam data after target replacement, the beam flatness, symmetry, output factor, and percent depth dose (PDD) were measured and compared with the commissioning data. The difference between the referenced and measured data for flatness and symmetry exhibited a coincidence within 0.3% for both 6 MV and 10 MV, and the difference of the PDD at 10 cm depth ($PDD_{10}$) was also within 0.3% for both photon energies. Also, patient-specific quality assurances (QAs) were performed with gamma analysis using a 2-D diode and ion chamber array detector for eight patients. The average gamma passing rates for all patients for the relative dose distribution was $99.1%{\pm}1.0%$, and those for absolute dose distribution was $97.2%{\pm}2.7%$, which means the gamma analysis results were all clinically acceptable. In this study, we recommend that the beam characteristics, such as beam profile, depth dose, and output factors, should be examined. Further, patient-specific QAs should be performed to verify the changes in the overall beam delivery system when a target replacement is inevitable; although it is more important to check the beam output in a daily routine.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.31 no.6B
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• pp.515-522
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• 2011

The hydrodynamic models are widely used in the research for analysis of flow characteristics and design of hydraulic structure and river channel. These models need to be calibrated with observed data. But, there are few field data of two-dimensional flow velocity in flood because the direct measurement of the flood flow velocity are very dangerous. For this reason the results of two-dimensional numerical models are usually calibrated and verified with only a few observed data. Moreover, the verification of numerical models for the design flood is usually carried out using the result of one-dimensional model, HEC-RAS. In this study, using the flow velocity profile extracted from the aerial photos of a flood of the Tone River in Japan, two-dimensional numerical models, RAM2 in RAMS, RMA2 in SMS, and one-dimensional numerical model, HEC-RAS which are most widely used in research and design work are verified and the validity for verification of two-dimensional models with HEC-RAS is reviewed. The results showed that the water surface elevation of HEC-RAS, RAM2 and RMA2 models have similar results with observed data. But, the velocity results of RAM2 and RMA2 models in the floodplain have some difference with the velocity from aerial photo analysis. And the velocity result of HEC-RAS has big difference with the sectional averaged value of velocity from aerial photo analysis.