• Journal of radiological science and technology
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• v.44 no.3
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• pp.247-252
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• 2021

As the number of single-person households increases, the consumption of bottled water is increasing. In addition, as the public's interest in radioactivity increases, interest in the field of living radioactivity is also increasing. Since drinking water is an essential element in our daily life, it must be safe from radioactivity. In this study, gamma radiation of drinking spring water was measured and internal exposure dose evaluation was performed to determine its harmfulness. K-40 and uranium-based radioactivity analysis was performed through a high-purity germanium detector, and as a result, drinking water was detected somewhat higher than that of mixing water. Since there is no regulation on the natural radioactivity concentration in Korea, it was compared with the U.S. Environmental Protection Agency Drinking Water Regulations and World Health Organization standard. As a result, there were some items that exceeded standards. Internal exposure was evaluated according to the effective dose formula of ICRP 119. As the result was derived that a maximum of 1.17 mSv per year could be received. This result means that the dose limit for the general public may be exceeded, and it was judged that it is necessary to set an appropriate standard value and present a recommendation value through continuous monitoring in the future.

• Journal of the Korea Convergence Society
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• v.12 no.4
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• pp.87-94
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• 2021

While the shielding substances of radiation shields in medical institutions are beginning to be replaced by environmentally friendly materials, radiation protection according to the shielding properties of environmentally friendly substances is becoming an important factor rather than the existing lead shielding properties. Tungsten and barium sulfate are representative shielding materials similar to lead, and are made in sheets or fiber form with eco-friendly materials. Ytterbium is an impermeable material used as a fluorine compound in the dental radiation field. This study aims to evaluate the shielding performance in the x-ray shielding area by comparing the shielding properties of ytterbium by energy band and that of existing eco-friendly materials. When three types of shielding sheets were fabricated and tested under the same process conditions, the shielding performance of the medical radiation area was about 5 % difference from tungsten. Furthermore, shielding performance was superior to barium sulfate. In the cross-sectional structure of the shielding sheet, there was a disadvantage that the arrangement of particles was not uniform. Ytterbium oxide showed sufficient potential as a medical radiation shielding material, and it is thought that it can improve the shielding performance by controlling the particle arrangement structure and particle size.

• Analytical Science and Technology
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• v.15 no.3
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• pp.196-213
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• 2002

The alkylphenols, chlorophenols and bisphenol A were determined by gas chromatography/mass spectrometry-selected ion monitoring mode followed by three work-up methods for comparison; EPA method, isoBOC derivatization method and TBDMS derivatization method. Eleven phenols in water samples were extracted with dichloromethane. Also, solid-phase extraction (SPE) with XAD-4 and subsequent conversion to isobutoxycarbonyl derivatives or tert.-butyldimethylsilyl derivatives for sensitive analysis with the selected ion-monitoring (SIM) mode. The recoveries were 85.1~109.9% (EPA method) and 90.3~126.6% (isoBOC derivatization and TBDMS derivatization), respectively. The method detection limit of bisphenol A for SIM were 0.732 ${\mu}g/{\ell}$ (EPA method), 0.002 ${\mu}g/{\ell}$ (isoBOC derivatization) and 0.021 ${\mu}g/{\ell}$ (TBDMS derivatization). The SIM responses were linear with the correlation coefficient varying 0.9755~0.9981 (isoBOC derivatization), and 0.9908~0.9996 (TBDMS derivatization). When these methods were applied to treated wastewater sample from a polyethylene plant, the concentrations of 11 phenols were below the method detection limit.

• The Journal of the Korea Contents Association
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• v.22 no.1
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• pp.99-115
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• 2022

In this study, domestic academic journal papers on tax compliance, tax consciousness, and faithful tax payment (hereinafter referred to as "tax compliance") were comprehensively analyzed from an interdisciplinary perspective as a representative research topic in the field of tax science. To achieve the research purpose, topic modeling technique was applied as part of text mining. In the flow of data collection-keyword preprocessing-topic model analysis, potential research topics were presented from tax compliance related keywords registered by the researcher in a total of 347 papers. The results of this study can be summarized as follows. First, in the keyword analysis, keywords such as tax investigation, tax avoidance, and honest tax reporting system were included in the top 5 keywords based on simple term-frequency, and in the TF-IDF value considering the relative importance of keywords, they were also included in the top 5 keywords. On the other hand, the keyword, tax evasion, was included in the top keyword based on the TF-IDF value, whereas it was not highlighted in the simple term-frequency. Second, eight potential research topics were derived through topic modeling. The topics covered are (1) tax fairness and suppression of tax offenses, (2) the ideology of the tax law and the validity of tax policies, (3) the principle of substance over form and guarantee of tax receivables (4) tax compliance costs and tax administration services, (5) the tax returns self- assessment system and tax experts, (6) tax climate and strategic tax behavior, (7) multifaceted tax behavior and differential compliance intentions, (8) tax information system and tax resource management. The research comprehensively looked at the various perspectives on the tax compliance from an interdisciplinary perspective, thereby comprehensively grasping past research trends on tax compliance and suggesting the direction of future research.

• Membrane Journal
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• v.27 no.5
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• pp.375-388
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• 2017

Wastewater treatment (WWT) technology has been developing from simple pollutant treatment to energy and resource-saving advanced technology, and various technologies combined with IT and BT are developed to minimize the amount of pollutant and toxic substance discharge to the public water areas and to improve operational efficiency. To examine the development trend of domestic wastewater treatment technology, the registered patent technologies were surveyed, classified and analyzed by year and sector. This paper considers the status of patent registration related to WWT from 2010.1 to 2017.5 in terms of the number of specific technical areas, and the trends are analyzed based on the 10 categorization field such as biological and physicochemical treatment process, equipment and device, material, sludge treatment, membrane, process control and 42 specific technical areas. A total of 3,356 patents have been registered since 2010, and the number of patents has been decreasing since the peak at 2013 and maintains 3~400 per year. The total number of patents has not yet been less than other countries, but the number of patents of more advanced technologies, which can lead the global market, such as process monitoring, new concept processing and equipment technologies is still insufficient compared to developed countries.

• Korean Journal of Biological Psychiatry
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• v.20 no.2
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• pp.54-60
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• 2013

Objectives The purpose of this study is to find the influential clinical and physical characteristics which affect apnea-hypopnea index (AHI) in suspected obstructive sleep apnea (OSA) patients. Methods We evaluated the comprehensive factors including sleep related symptoms, clinical scales, medical history, substance use, and anthropometric data of the 119 participants who complained of the symptoms of OSA. All the participants underwent attended-full night laboratory polysomnography. The correlation and multiple regression analysis were conducted to find the influential and predictive factors of AHI. Results A multiple linear regression model 1 showed that higher AHI was associated with higher body mass index (BMI)(p < 0.001) and higher frequency of observed apnea (p = 0.002). In multiple linear regression model 2, AHI was associated with higher BMI (p < 0.001) and loudness of snoring (p = 0.018). Conclusions The present preliminary results suggest that BMI and observed apnea are most influential factors that affect AHI in suspected OSA patients. In the future study we will design the prediction formula for the OSA and AHI, which is useful in the clinical medical field.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.51 no.spc1
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• pp.264-268
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• 2006

This study investigated the effect of self-incompatibility control substance 'Apple plus' in improving self-fertilization and quality on apple. Results showed that the rate of fruit setting of disc florets of Fuji apple in the open field increased from 17.2% in 2004 to 44.4% in 2005 for the treated plots and from 0.5% in 2004 to 3.0% in 2005 for the control. In the case of using net covering, the rate of fruit setting increased from 3.3% in 2004 to 5.2% in 2005 for the treated plots and from 0.4% in 2004 to 0.1% in 2005 for the control. For the quality of apple fruits, results showed that there was no significant difference on the fruit L/D and firmness for both control and treated plots. However, the number of seeds was affected by the different substances which produced the following average number of seeds: control, 0.9; IS-1, 1.2; IS-2, 1.2; IS-3, 1.5 and IS-4, 0.7. The SSR genetic analysis showed that the rate of self-fertilization was highest for IS-1 (100%), followed by IS-2 (73%), IS-3 (68%), IS-4 (62%) and control (0%).

• Journal of the Korean Institute of Landscape Architecture
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• v.39 no.2
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• pp.73-90
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• 2011

The purpose of this research was to find out the characteristics of secluded cultural landscapes that were retained by Eyogye Cho Lyeo(漁溪 趙旅) as a recluse or a schola at the early time of Chosun dynasty through his poems, residential site and his successors' landscapes. The study sites were selected such as Wonbukgae(院北齋), Chamijeong(採薇亭), Gomaam (叩馬巖) and his graveyard. In order to do that, Wonbukgae, Chamijeong, Gomaam and his cemetery were selected as studying sites. Also researching methods were used by grasping the landscape elements through reading ancient books such as "Eyogyezip(漁溪集)", field-researching, analyzing characters of his secluded landscapes and interpreting his poem's meaning. This research found that: 1) After Danjong(端宗)'s dethronement, he returned to his home town and never come out to the world again. He wanted to keep fidelity to his king forever. 2) He was affected for his seclusion from many people who were Ryu Gyebun(柳桂芬), Bae Junghu(裵仲厚) as his classmates at Sunggyungwan(成均館). Also Won ho(元昊) and Kim Sisyub(金時習) as members of Sangyuksin(生六臣) affected him for sake of their seclusion. 3) The meaning of his seclusion expressed the notation of seclusion as a fisherman from his pen name as 'Yeogye'. Also this kind culture has very particular behavior such as concentration phenomenon of action, absolute eccentricity of seclusion, tourism of nature and deep knoledge of feng shui, strong persistence of seclusion and confucian practical attitude of filial behavior. 4) The secluded cultural landscape is divided to four regions. They have two types of landscape such as secluded cultural landscape of his lifetime and landscape transmission of his posterity and scholars. 5) The interpretation of his poems and their aesthetic analysis found two characters. His poems were expressed by landscape substance like plants, natural and man-made elements. Their theme was confucian, peaceful and faithful seclusion.

• Journal of The Korean Association For Science Education
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• v.22 no.2
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• pp.276-285
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• 2002

In this study the concepts for science learning of physics and earth science presented in the seventh grade science textbooks for the seventh national curriculum of Korea approved by the ministry of education were analyzed in terms of the concrete and formal concept level. The parts of textbook analyzed for science learning consist of three sections in physics such as light, force, and waves, and three sections in earth science such as the structure of the earth, the substance of crust, and the movement and composition of the ocean. The analyzed results showed that the number of scientific concepts were differed from 54 to 74 in physics and from 86 to 120 in earth science depending upon publishers. In general, the concepts for science learning in the physics were found to be more in the formal level than the concrete level. However, the concepts for science learning in earth science were found to be more in the concrete level than the formal level. The analyzed results suggest that the concepts of science learning should be considered the learner's cognitive level and the sections should be disposed depending on the degree of difficulty for writing the science textbook. Therefore, it seems to be important to review carefully whether the textbook meets the object of the seventh curriculum of Korea during the process of the investigation for the science textbook.

• Journal of the Society of Disaster Information
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• v.17 no.1
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• pp.10-24
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• 2021

Purpose: The purpose of this study is to determine the dangers of biodiesel and general diesel mixtures currently used as alternative fuels by equipment (tag method and penski Marten method) and to determine the difference between flash point and combustion point (closed, open) according to test methods. It is intended to be used as a reference material for identification and evaluation of firecausing substances by confirming the risk of mixtures by comparative analysis and measurement, and establishing a risk assessment method for chemical substances. Method: Flash point test method and result treatment were tested based on ASTM and KS M mode, which are tag sealing and pen schematense test methods used as flash point and combustion point test methods for crude oil and petroleum products. The manufacturer of the equipment used in this experiment was a test equipment that satisfies the test standards of KS M 2010 with equipment produced by TANAKA of Japan. The flash point and combustion point were measured, and the flash point according to the test method of biodiesel and general diesel mixture ( Closed, open), and the ignition point of a mixture of biodiesel and general diesel was compared and analyzed for ignition risk compared with conventional diesel. Results: Looking at the experimental results, first, as an analysis of the risk of flammability of the mixture, the flash point of a substance containing 70% biodiesel was found to be about 92℃ based on general diesel with a flash point of 64.5℃, and gasoline and biodiesel or When the biodiesel mixture was synthesized, it was confirmed that the flash point tends to decrease. In addition, the difference between the flash point and the combustion point was analyzed as about 20 ~ 30℃, and when a small amount of gasoline or methanol was mixed, the flash point was lowered, but it was confirmed that the combustion point was similar to that of the existing mixture. Conclusion: In this study, in order to secure the effectiveness of the details of the criteria for judging dangerous materials in the existing Dangerous Materials Safety Management Act, and to secure the reliability and reproducibility of the judgment of dangerous materials, we confirm the criteria for judging the risk of the mixture through an experimental study on flammable mixtures. It will be able to provide reference data for experimental criteria for flammable liquids that are regulated in the field. In addition, if this study accumulates know-how on experiment by test method, it is expected that it can be used as a basis for research on risk assessment and research on dangerous goods.