• Title/Summary/Keyword: contamination degree

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An Experimental study to estimate physical properties of porous media by a permittivity method (유전율법에 따른 다공질 매질의 특성 파악을 위한 실험적 연구)

  • 김만일;니시가끼마코토
    • The Journal of Engineering Geology
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    • v.13 no.4
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    • pp.405-418
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    • 2003
  • Measurements of volumetric water content and saturation of porous media are very important factors in understanding the physical characteristics of soil, groundwater recharge by rainfall, pollutant movement, and slope failure. To measure such physical parameters, a permittivity method using electromagnetic wave is applied and use is made of the special permittivity response of understand to water and ethanol. In particular, the estimation is required because permittivity is influenced by the nature of the underground environment. In this study, we carried out experiments on the relative dependency of soil density, temperature and salinity of standard sand and granitic weathered soil using FDR-V system (Frequency domain reflectometry with vector network analyzer) within a frequency range of 1 - 18 GHz. The results of the study showed that the dielectric constants of standard sand and granitic weathered soil increased with increased volumetric water content of soil. However, the dependency of soil density was found to be a little low. Changes of dielectric constant with temperature appeared definitely in the real part of 1 GHz. That is, the dielectric constant of real part at 1 GHz of water and standard sand increased with the rise of temperature. However, ethanol showed decreased tendency. The study also showed that dielectric constant increased with increase in salinity at imaginary part of 1 GHz. It could be concluded from this study FDR-V system can adequately measure the physical properties of soil and the degree of salinity concentration of porous media within 1 GHz frequency range using dielectric constant.

Characteristics of indoor air quality in the overground and underground railway stations (지상과 지하역사의 실내공기질 특성과 외기영향 평가)

  • Namgung, Hyeong-Kyu;Song, Ji-Han;Kim, Soo-Yeon;Kim, Hee-Man;Kwon, Soon-Bark
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.17 no.5
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    • pp.17-25
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    • 2016
  • In this study, the air quality of underground and overground railway stations was evaluated focusing on the degree of influence of the outside air quality. The measured components were particulate matter ($PM_{10}$), carbon dioxide ($CO_2$), carbon monoxide (CO), nitrogen dioxide ($NO_2$), formaldehyde (HCHO), ozone ($O_3$), total airborne bacteria (TAB), total volatile organic carbon (TVOC), and Radon (Rn), which are included in the maintenance standards and recommended standards of the Indoor Air Quality Management Act. Also, the indoor/outdoor concentration ratios of $PM_{10}$, $NO_2$, and $O_3$ were calculated to estimate the influence of the outdoor air quality. The concentrations of $PM_{10}$ HCHO, TVOC, $NO_2$, and Rn in the underground stations were found to be higher than those in the overground stations. These results indicate that the (present) generation of contaminants are caused by the indoor source of the underground station. The ozone concentration of the overground stations was higher than that of the underground stations, which indicates that the outdoor ozone concentration influenced that of the overground stations directly. Thus, methods of improving the IAQ should take into consideration the types of contamination.

Heavy Metals in Sediments and Organisms from Tidal Flats along the Mokpo Coastal Area (목포연안 갯벌 및 서식생물에서의 중금속 함량)

  • 나춘기
    • Economic and Environmental Geology
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    • v.37 no.3
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    • pp.335-345
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    • 2004
  • Total and extractable contents of heavy metals were measured in sediment and seafood from Bukhang and Boggil-ri tidal flats along the Mokpo coastal area, south-western part of Korean peninsular in order to assess the degree of metal pollution, metal bioavailability and metal hioaccumulation. The metal concentrations, except Pb were found to be greater than the background concentrations of sediments indicating the progress of cumulative contamination by anthropogenic origin of metals. The order of extractable metal concentrations in sediments were Mn(32-53 mg/kg)>Zn(14-42 mg/tg)>Cu(2.5-17.0 mg/kg)>Pb(2.4-6.8 mg/kg)>Cd(0.5-0.7 mg/kg). However, the amount of metals associated with extractable fraction of sediments were significantly high in Bukhang relative to Boggil-ri. Significant bioaccumulation of all metals, except Pb were observed in seaweed and benthos. The order of bioaccumulation of metals were: in concentration; all biota commonly, Mn(129-374 mg/kg)>Zn(19-106 mg/kg)>Cu(6-87 mg/kg)>Cd(4.6-7.6 mg/kg)>Pb(0.2-3.7 mg/kg), in BCF; Enteromorpha, Cd>Mn>Cu>Zn>Pb, Ilyoplax deschampsi, Cu>Cd>Mn>Zn>Pb, Urechis unicinctus, Cd>Zn>Mn>Cu>Pb. Some metal concentrations of Enteromorpha, especially Cu, Zn, weakly Pb in bukhang, Mn, Cd in boggili-ri, were correlate well with concentrations in sediment, indicating relatively more contaminated by the anthropogenic origin of metals in each tidal flat. The results clearly indicate that the seafood of bukhang, even of Boggili-ri known as clean area, are contaminated with metals.

Study on Prevention of Foreign Material Formation in Sclerotium of Poria cocos. (복령 균핵내 이물질 생성 방지 연구)

  • 장현유
    • Korean Journal of Plant Resources
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    • v.13 no.2
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    • pp.147-153
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    • 2000
  • Experiments were carried out to determine the effects of culturing conditions DCI(Day required for Colonization after Inoculation), CR(Contamination Rate), MD(Mycelial Density), DPI(Day required for Primordial sclerotia formation after Inoculation), yields, and degree of the foreign materials formations in Poria cocos sclerotia. The upper and bottom side of wood logs were covered with gauze, rice hull and floating leaves, vinyl, or covering cloth in order to prevent foreign material formations in p. cocos. The major results were positive in the order of rice hull, floating leaf, vinyl, gauze, and covering cloth covered and dwindled. In case of the upper and bottom sides of the wood logs covered with rice hull, DCI required 50 days more when compared with the control group(45 days) and CR was 0%, while the control group showed 2% CR. MD was excellent in case of conventional methods as against control's. DPI required 17~20 days less when compared with the control group(82 days). Yields of p. cocos in case of the upper and bottom side of wood logs covered with rice hull were 5.87kg, which is 35.7% higher than that of the control group(4.33kg), and 5.62kg in the case of upper sides cover only(increased by 29.8% compared with control), and 5.59kg in the case of bottom side cover only(increased by 29.1% compared with control), and foreign materials were none. In a separate experiment, where the upper and bottom sides of wood logs were covered with rice hull to prevent the foreign material formation, the results were as follows : Sclerotia formation status and quality of P. cocos were effective in the order of 20cm, 40cm, and 60cm of buring depth and dwindled. In 20cm of burying depth, DCI was shortened by 5 days and CR was none, while the control group showed 2% CR. MD was remarkably fine at the mulched conditions. DPI was shortened by 20 days when compared with the control(62 days).

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Evaluation of Indoor Mold Exposure Level in dwelling Using DNA-Based Mold Assessment Method (DNA 기반 곰팡이 평가기법을 활용한 주택의 실내 곰팡이 노출수준 평가)

  • Hwang, Eun-Seol;Seo, Sung Chul;Lee, Ju-Yeong;Ryu, Jung-min;Kwon, Myung-Hee;Chung, Hyen-Mi;Cho, Yong-Min;Lee, Jung-Sub
    • Journal of Korean Society of Occupational and Environmental Hygiene
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    • v.28 no.4
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    • pp.382-392
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    • 2018
  • Objective: Allergic diseases such as asthma due to fungal exposure in houses have increased, and proper management is urgent. Mold can grow in the air, floor, walls, and other areas according to environmental conditions, and there are many limitations to the conventional methodology for examining fungal exposure. For this reason, the degree of fungal contamination is being evaluated by ERMI (Environmental Relative Moldiness Index), a quantitative analysis method proposed by the EPA. In this study, we compared ERMI values between water-damaged dwellings and non-damaged ones to evaluate the effectiveness of Korean ERMI values. We also explored the association of ERMI values with the level of airborne mold and characteristics of dwellings. Methods: Floor dust was collected after installing a Dustream collector on the suction port of a vacuum cleaner. The collected samples were filtered to remove only 5 mg of dust, and DNA was extracted using the FastDNA SPIN KIT protocol. Results: The ERMI values were found to be 19.6 (-6.9-58.8) for flooded houses, 7.5 (-29.2-48.3) for leaks/condensation, and 0.8 (-29.2-37.9) for non-damaged dwellings. The airborne concentration of mold for flooded, leakage or condensed, and non-damaged houses were $684CFU/m^3$, $566CFU/m^3$, and $378CFU/m^3$, respectively. The correlation between ERMI values and the levels of airborne mold was low (R = 0.038), but a weakly significant association of the ERMI values with the concentration of particulate matter ($PM_{10}$) was observed as well(R=0.231,P<0.05). Conclusions: Our findings show that the reference value using ERMI can be used to distinguish water-damaged and non-damaged dwellings. It is believed that ERMI values could be a promising tool for assessing long-term fungal exposure in dwellings.

Antifouling Effect of an Ultrasonic System Operating at Different Frequencies (주파수 변동에 따른 초음파방오장비의 파울링제거효과)

  • Bae, Jin-Woo;Park, Guan-Sik;Ru, Myung-Lok;Park, Goun-Ha
    • Journal of the Korean Society of Marine Environment & Safety
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    • v.25 no.5
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    • pp.609-616
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    • 2019
  • When the fouling of a vessel occurs, its resistance at sea increases and there is a corresponding increase in fuel consumption. The maintenance cost of the vessel also increases because it is time-consuming to remove the fouling. To solve this problem and minimize environmental contamination of sea-water, there have been recent developments in anti-fouling paints as self-polishing copolymers that not include toxic elements such as tin. When these conventional techniques are applied to vessels, polishing is promoted during the operation whereby friction or vibration with seawater occurs. This leads to enhanced anti-fouling performance. However, when fouling is intensified such as during an anchorage, there is no flow of seawater and polishing is suppressed. This leads to a deterioration of the performance of anti-fouling. To solve these problems, we developed a system that induces vibration in a vessel during anchorage. As such, the deterioration of polishing due to insuf icient flow of seawater is inhibited. The reliability of the ultrasonic antifouling system was evaluated by calculating its repeatability. The removal efficiency of fouling of the proposed system was qualitatively evaluated using test specimens. The test revealed that the value of the coefficient of variation for the reproducibility of the frequency and amplitude was 0.2 % and 4.0 % on average. The degree of fouling of the specimens was the highest at 73.3 g in the No.5 sepcimen. Moreover, efficiency of fouling removal was 93.2 % on average compared to the specimens without the proposed system.

Polarimetry of solar system small bodies using the Seoul National University 61cm telescope and TRIPOL

  • Jin, Sunho;Ishiguro, Masateru;Kwon, Yuna Grace;Geem, Jooyeon;Bach, Yoonsoo P.;Seo, Jinguk;Sasago, Hiroshi;Sato, Shuji
    • The Bulletin of The Korean Astronomical Society
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    • v.44 no.1
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    • pp.64.2-64.2
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    • 2019
  • It is known that lights scattered by comets and asteroids are partially polarized. From polarimetric observations of those objects, we can investigate physical properties, such as albedos, sizes of cometary dust particles and regolith of asteroids. Since the polarization degrees of those objects highly depend on their phase angles (Sun-object-observer's angles), long-term monitoring observations are required. Moreover, comets show unforeseeable activations (i.e., outbursts) which need follow-up observations to understand the mechanism. In order to realize such monitoring and transient observations, we installed the Triple-Range Imager and POLarimeter (TRIPOL) on the 61cm telescope of Seoul National University (Hereafter, SNU) Gwanak campus. With this combination, we can obtain g', r', i' bands photopolarimetric images simultaneously with $8.0^{\prime}{\times}8.0^{\prime}$ field of view and pixel resolution of 0.94" pixel-1. Here, we make a presentation regarding the photometric and polarimetric performances of TRIPOL on the SNU 61cm telescope. In addition, we introduce initial polarimetric results of asteroid and comets with the instruments. First, we determine the limiting magnitudes (defined as magnitudes for S/N=5) of $15.17{\pm}0.06$ (g'-band), $15.68{\pm}0.01$ (r'-band), $16.24{\pm}0.03$ (I'-band), respectively, with total 240-seconds exposure (four 60-seconds exposure images, each was taken at different rotation angle for the half-wave plate). Second, we found that the instrumental polarization is negligibly small, ($-0.32{\pm}0.04%$ in the g', $-0.36{\pm}0.05%$ in the r' and $-0.21{\pm}0.04%$ in the i'-bands), while the polarization efficiencies are large enough to maximize the performance (i.e., $97.52{\pm}0.03%$ in the g', $98.83{\pm}0.02%$ in the r' and $99.15{\pm}0.02%$ in the i'-bands). With the instruments, we made observations of three Jupiter-family comets, 21P/Giacobini-Zinner, 38P/Stephan-Oterma, and 46P/Wirtanen and plan to observe one near-Earth asteroid, (433) Eros, on a trial basis. Especially for comets, we discriminate signals from dust and gas to eliminate gas contamination, which are known to change observed degree of linear polarization, using multi-band images. We confirm that the phase angle dependency of these comets are consistent with previous observations, probably because polarimetric property of Jupiter-family comets are broadly homogeneous unlike asteroids. We will also describe future observation plans using TRIPOL and SNU 61cm telescope.

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A Study Practice of Infection Control for Dental Office and Dental Hygienist and Bacterial Contamination of Dental Office Surface (치과 의료기관 및 치과위생사의 감염관리 실천도와 진료실내의 표면 세균오염도에 대한 연구)

  • Yun, Kyoung-Ok;Bae, Sung-Suk;Choi, Young-Suk
    • The Journal of the Korea Contents Association
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    • v.19 no.5
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    • pp.511-519
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    • 2019
  • The purpose of this study was to investigate the status of infection control in dental office and the degree of infection control practice of dental hygienists. A self-reported questionnaire was answered by 193 dental hygienists working in dental hospitals or dental clinics in Gyeonggi and Incheon areas. The number of bacteria was measured sample of surface dental unit chair shoulder backrests and light handles from 19 dental hospitals and 28 dental clinics. It was responded that impression or occlusion bodies were routinely disinfected in 52.6% of the dental hospitals and dental prosthesis were routinely disinfected in 46.4% in dental clinics. The dental hospital and clinics disinfect the surface each 26.3%, 25% after the patient treatment. The dental hospital and clinic were detected bacteria $5.02^*10\^3CFU/mL$, $1^*10\^4CFU/mL$, from dental unit chair backrest, respectively and $8.32^*10\^3CFU/mL$, $4.26^*10\^4CFU/mL$ from light handles, respectively. At the conclusion of this investigation, it can be kept from infection source in dental office is to make the right selection and use of the personal protective equipments and to improve the practice level by regular and active education. The same infection control practice should be done by institutionalizing and mandating infection control practice.

Review Paper for Characterization of Photoionization Detector-Direct Reading Monitors (산업현장에 활용되는 PID 직독식장비의 특성 고찰)

  • Sungho Kim;Hae Dong Park;Eunsong Hwang
    • Journal of Korean Society of Occupational and Environmental Hygiene
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    • v.33 no.2
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    • pp.93-102
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    • 2023
  • Objectives: With the evolution of direct reading sensors, it is possible to monitor several substances through telecommunication. However, there are some limitations on the use of direct reading technologies in the Occupational Safety and Health Act in South Korea, which only applies to detector tubes, noise, heat, and carbon monoxides. The number of chemicals and their amount of use have been continuously increasing in South Korea. The Ministry of Employment and Labor (MoEL) has concerns about worker's health because exposure is only covered for about 1.2% of all distributed chemicals. Using a direct reading monitor with photoionization detectors (PID-DRMs), gases and vapors chemicals can be measured. Based on the data, business owners are able to create corrective strategies, provide better working routines, and select correct respiratory equipment. PID-DRMs are less expensive and easier to handle for an owner voluntarily controlling chemicals emitted in the workplace. However, there are several limitations on using these PID-DRMs to the degree that the MoEL has not been able to select a legal monitor. The aim of this study was to review previous studies related to PID-DRMs and identify the characterization and limitation on PID-DRMs. Methods: To search for related studies on PID-DRMs, key words were used including direct reading monitors/instruments and/or photoionization detectors. Through that, four domestic and 15 international studies were reviewed. Results: Studies on PID-DRMs were conducted by chamber (enclosed, dynamic, walk-in) and in the field (experimental environment, actual environment). The concentration of PID-DRMs and charcoal tubes were compared for a single substance or mixture, or within the PID-DRMs. There was a high correlation between the two concentrations, but it did not meet the accuracy criteria (95% confidence interval, within 25%) of the NIOSH technical report (2012). In addition, differences in measured values occurred according to environmental factors (temperature, humidity) and high concentration, and concentration values tended to be underestimated due to contamination of the sensor. As a way to improve the accuracy of PID concentration, it was proposed to use correction factors, charcoal tube-based correction factors, or to calibrate the PID-DRMs in the same environment as the workplace. Conclusions: PID-DRMs can likely be used by business owners for the purpose of voluntarily managing the workplace environment, and it is expected that it will be possible to use them as legal equipment if a PID sensor can be upgraded and the limitations of the sensor (temperature, humidity, high concentration evaluation, sensor pollution) can be overcome in the near future.

Ecological Studies on the Occurrence of Rice False Smut (벼 이삭누룩병(病)의 발생(發生) 생태(生態)에 관(關)한 연구(硏究))

  • In, Moo Seong;Park, Jong Seong;Yu, Seung Hun
    • Korean Journal of Agricultural Science
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    • v.12 no.2
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    • pp.242-252
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    • 1985
  • In order to get information on the ecology of rice false smut, germination ability and pathogenicity of sclerotia and chlamydospores of the pathogen, environmental conditions affecting the disease outbreak and varietal resistance have been investigated. 1. The degree of outbreak of rice false smut was higher in the upland rice in comparison with the paddy field rice in respect to the number of affected grains per ear, the size and weight of smut balls formed on affected grains as well as the ratio of sclerotial formation produced on smut balls. 2. Germination percentage and days required for germination of overwintered sclerotia placed on the soil surface in July were 81% and 19 days, respectively, while those of overwintered sclerotia treated in May were 60-70% and 41 days. Sclerotia placed on the soil surface or under 1 cm depth of the soil surface and incubated at $25-30^{\circ}C$ were germinated well, whereas those placed under 3 cm or 5 cm depth of the soil surface were not germinated at all. Germinability and stroma productivity of sclerotia were reduced when the sclerotia were cutted into small pieces. 3. The average number of stroma formed on a sclerotium was six and that of perithecia formed in a stroma was about 50 to 140. 4. Percentage of germination of chlamydospores on the yellow balls was very high and was decreased as the color of the balls being darken with maturation. 5. Panicle of rice plants were successfully infected by injection inoculation with suspention of ascospores and chlamydospores of the pathogen to the sheaths at the booting stages, while seeding infection by spraying with suspensions of chlamydospores was unsuccessful. 6. More number of infected grains was distributed on basal parts of an affected ear than that of infected ones distributed upper parts of the ear, when the affected ear was divided into five parts from its basal portion to the apical of the ear. 7. The occurrence of the disease was more severe in the late maturing varieties of rice in comparison with the early maturing varieties. 8. When the level of nitrogen applied was increased, the incidence of disease increased, and the infection percentage of the disease was increased as the transplanting date was delayed. 9. The weight of panicles and 1000 kernels and the ratio of ripenness were reduced, and the contamination degree of grains with chlamydospores were increased as the number of smut balls per panicle were increased.

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