• Korean Chemical Engineering Research
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• 제46권4호
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• pp.806-812
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• 2008

귀금속촉매 존재하에서 암모니아 전환반응은 배가스내의 암모니아를 처리하는데 중요한 기술이다. 과잉용액 함침법을 이용하여 $Pt-Rh/Al_2O_3$, $Pt-Rh/TiO_2$, $Pt-Rh/ZrO_2$, $Pt-Pd/Al_2O_3$, $Pd-Rh/Al_2O_3$, $Pd-Rh/TiO_2$, $Pd-Rh/ZrO_2$, $Pt-Pd-Rh/Al_2O_3$, $Pd/Ga-Al_2O_3$, $Rh/Ga-Al_2O_3$, 그리고 $Ru/Ga-Al_2O_3$의 촉매를 제조하였다. 제조된 촉매는 1/4"의 반응기에 $10,000{\sim}50,000hr^{-1}$의 공간속도 조건하에서 촉매활성능 실험을 수행하였다. 암모니아의 초기농도는 2,000 ppm (나머지는 공기)으로 유지하였다. $T_{50}$는 암모니아 전환율이 50%일 때를 나타내는 온도를, $T_{90}$은 90%의 전환율일 때의 온도를 나타낸다. 알루미나를 담지체로 사용했을때의 $T_{50}$와 $T_{90}$은 다른 담체를 사용했을때의 $T_{50}$와 $T_{90}$보다 훨씬 낮았다. Pd-Rh촉매의 경우 $Al_2O_3$를 담체로 사용하였을 때 $ZrO_2$나 $TiO_2$보다 저온 활성이 우수하게 나타났다. 황산화물의 피독실험 결과 본 연구에서는 최종적으로 $Pt-Rh/Al_2O_3$ 촉매가 다른 촉매에 비하여 우수함을 보였다. 실험결과 Pt-Rh가 암모니아 전환공정에서 유용한 촉매라는 사실을 알 수 있다.

• 대한소아치과학회지
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• 제24권2호
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• pp.460-474
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• 1997

The purpose of this study was to evaluate and compare the effectiveness of various low-viscosity resin systems used as rebonding agents to prevent microleakage at the margins of class I composite resin restorations. Seventy sound human premolars were selected for experiment. Class I cavities were prepared and each cavity was conditioned with a 37% phosphoric acid for 15 sec, rinsed with water for 15 sec, and dried with compressed air. Bonding agent(Scotchbond Multipurpose, 3M Co.) was applied and a hybrid composite resin (Z-100, 3M Co.) was placed using an incremental technic. The excess cured composite resin was carefully removed with Sof-Lex discs(3M Co.) to expose the original margins of the cavity. The following seven groups were established : group 1 was not rebonded and used as control group ; group 2 was rebonded with a Scotchbond Multipurpose(3M Co.) and finished ; group 3 was rebonded with a Fortify(BISCO) and finished ; group 4 was rebonded with a Concise white sealant(3M Co.) and finished ; group 5 was rebonded with a Concise white sealant(3M Co.) and not finished ; group 6 was rebonded with a P&F sealant(BISCO) and finished; group 7 was rebonded with a P&F sealant(BISCO) and not finished. The specimens were then subjected to 500 thermocycles between 5 & 65 with a 10 see dwell time and immersed in 2% methylene blue dye solution for 24 hours and sectioned with low-speed diamond cutter into two part under water condition. The extent of microleakage at rebonded margins was evaluated microscopically and scored for dye penetration according to the following scale : 0=no dye penetration ; 1=dye penetration to half-way along axial wall between enamel surface and DEJ ; 2=dye penetration beyond halfway along axial wall between enamel surface and DEJ ; 3=dye penetration to the full depth of DEJ or beyond DEJ. Selected samples were prepared for SEM observation to determine the depth of penetration of the rebonding agent into the marginal interface. The obtained results were as follows: 1. In the group 2 and 3, which is rebonded with a Scotchbond Multipupose and Fortify, dye penetration score were decreased significantly than that of group 1 (P<0.05), but group 4 and 6 were not statistically different from group 1(P>0.05). 2. There were significant differences between group 4, 6 and group 5, 7 when compared by dye penetration score (P<0.05). 3. In the SEM observation, Scotchbond Multipurpose and Fortify were penetrated within $30-40{\mu}m$ depth of the outermost surface. However, both sealants were failed to penetrate into the debonded interface.

• Tuberculosis and Respiratory Diseases
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• 제69권6호
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• pp.426-433
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• 2010

Background: Persistent cough has recently been found to be associated with Chlamydia pneumoniae infection. We aimed to investigate the infection rate of C. pneumonia in adult patients with chronic cough. Methods: We recruited 68 patients with persistent cough lasting in excess of 3 weeks, who visited Kangdong Sacred Heart Hospital from January 2005 to August 2005. On the first visit, chest and paranasal sinuses radiography, skin prick test of common allergens, and induced sputum samples for C. pneumoniae were performed in all of patients. Further evaluation for diagnosis included a methacholine provocation test and eosinophil counts in induced sputum. Results: The most common cause of chronic cough was upper airway cough syndrome (UACS) (26.5%), followed by eosinophilic bronchitis (20.6%) and cough variant asthma (16.2%). Idiopathic chronic cough was the cause in 33.8% of patients. The mean duration of cough was 11.7 months. C. pneumoniae was isolated by polymerase chain reaction (PCR) from one patient who had upper respiratory air way syndrome. Conclusion: Chlamydia pneumoniae appears to have a minor role as a cause of chronic cough in patients.

• 플랜트 저널
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• 제14권4호
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• pp.39-47
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• 2018

본 연구에서는 정격출력 500 MW로 연속운전 하는 표준석탄화력 발전설비의 출력을 300 ~ 500 MW로 변동운전하게 될 때 황산화물의 생성량과 탈황설비 흡수탑에서의 황산화물 배출농도 변화를 비교하고, 출력에 반비례하는 과다한 액기비 개선을 제안하였다. 저출력에서 연소효율 보정을 위해 과잉공기비를 높임에 따라 발생하는 연소가스량에 비해 상대적으로 황산화물의 비율이 낮아지기 때문에 고유황 연료일수록 고출력에서 유황성분의 생성농도가 상승하였다. 출력변동과 함께 탈황흡수탑 입구 황산화물 생성농도를 300 ~ 500 ppm으로 변화시켰을 때, 석회석 슬러리와 연소가스의 액기비는 10.99 ~ 16.27로 변화되었다. 따라서 저부하시 액기비 상승에 따른 잉여에너지저감을 위한 슬러리의 필요최소 유량은 300 MW 출력에서 황산화물 배출농도를 x라고 했을 때 다음 상관관계식을 추천한다. $y1[m^3/sec]=0.11x+3.74$

• 한국지하수토양환경학회지:지하수토양환경
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• 제26권3호
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• pp.37-49
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• 2021

There is domestic Soil Contamination Warning Standard (SCWS) as remediation standard concentration of contaminated soils. No risk should be observed at soil concentration less than SCWS. Therefore, SCWS was evaluated to confirm the risk assessment. Background Concentration of Soil (BGC) and target remediation concentration were also assessed. The results show that Excess Cancer Risk (ECR) of SCWS was the highest in the groundwater intake pathway (Adult: 6.27E-04, Child: 2.81E-04). Total Cancer Risk (TCR) was 7.76E-04 and 4.30E-04 for adult and child, exceeding reference value (10^-6). Hazard Quotient (Non-Carcinogenic Risk, HQ) was the highest in the indoor air inhalation pathway (Adult: 3.64E+03, Child: 8.74E+02). Hazard Index (Total Non-Carcinogenic Risk, HI) exceeded reference value 1. ECR of the BGC was the highest in the groundwater intake pathway (Adult: 1.71E-04, Child: 7.67E-05). TCR was 2.12E-04 for adults and 1.17E-04 for children, exceeding the reference value (10^-6). HQ was the highest in groundwater intake pathway (Adult: 4.10E-01, Child: 1.84E-01). HI was lower than reference value 1 (Adult: 4.78E-01, Child: 2.50E-01). The heavy metal affecting ECR was Arsenic (As). The remediation-concentration of As was 7.14 mg/kg which is higher than BGC (6.83 mg/kg). TCR of As should be less than reference value (10^-6), but it was higher for all of SCWS, BGC and target remediation concentration. Therefore, it is suggested that risk assessment factors should be re-evaluated to fit domestic environmental settings and SCWS should be induced to satisfy the risk assessment.

• 한국학교ㆍ지역보건교육학회지
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• 제22권4호
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• pp.49-60
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• 2021

Objectives: Laboratories have various latent physical, chemical, biological, and ergonomical factors according to the diversification and fusion of research and development activities. This study aims to investigate the chemical exposure concentrations of college laboratories and evaluate their health risks, and use them as basic data to promote the health of college students. Methods: The sampling and analysis of harmful chemicals in the air in laboratories were performed using Method 1500 of the U.S. National Institute for Occupational Safety and Health (NIOSH)의 Method 1500. The harmful chemicals in the laboratories were divided into carcinogenic and non-carcinogenic chemicals. Risk assessment was performed using the cancer risk (CR) for carcinogenic chemicals and using the hazard index (HI) for non-carcinogenic chemicals. Results: The harmful chemicals in college laboratories consisted of acetone, diethyl ether, methylene chloride, n-hexane, ethyl acetate, chloroform, tetrahydrofuran, toluene, and xylenes. They showed the highest concentrations in laboratories A (acetone 0.001~2.34ppm), B (chloroform 0.95~6.35ppm), C (diethyl ether 0.08~8.68ppm), and D (acetone 0.07~14.96ppm). The risk assessment result for non-carcinogenic chemicals showed that the HI of methylene chloride was 2.052 for men and 2.333 for women, the HI of N-hexane was 4.442 for men and 5.05 for women. Thus, the HI values were higher than 1. The risk of carcinogenic chemicals is determined by an excess cancer risk (ECR) value of 1.0×10^-5, which means that one in 100,000 people has a cancer risk. The ECRs of chloroform exceeded 1.0×10^-5 for both men and women, indicating the possibility of cancer risk. Conclusion: College laboratories showed the possibility of non-carcinogenic health risks for methylene chloride, n-hexane, tetrahydrofuran (THF), toluene, and xylenes, and carcinogenic health risks for chloroform, methylene chloride. However, this study used the maximum values of measurements to determine the worst case, and assumed that the subjects were exposed to the corresponding concentrations continuously for 8 hours per day for 300 days per year. In consideration of the nature of laboratory environment in which people are intermittently exposed, rather than continuously, to the chemicals, the results of this study has an element of overestimation.

• 한국환경보건학회지
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• 제49권2호
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• pp.108-117
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• 2023

Background: When particles are absorbed into the human body, they penetrate deep into the lungs and interact with the tissues of the body. Heavy metals in PM_2.5 can cause various diseases. The main source of PM_2.5 emissions in South Korea's atmosphere has been surveyed to be places of business. Objectives: The concentration of heavy metals in PM_2.5 near the Ulsan Industrial Complex was measured and a health risk assessment was performed for residents near the industrial complex for exposure to heavy metals in PM_2.5. Methods: Concentrations of heavy metals in PM_2.5 were measured at four measurement sites (Ulsan, Mipo, Onsan, Maegok) near the industrial complexes. Heavy metals were analyzed according to the Air Pollution Monitoring Network Installation and Operation Guidelines presented by the National Institute of Environmental Research. Among them, only five substances (Mn, Ni, As, Cd, Cr⁶⁺) were targeted. The risk assessment was conducted on inhalation exposure for five age groups, and the excess cancer risk and hazard quotient were calculated. Results: In the risk assessment of exposure to heavy metals in PM_2.5, As, Cd, and Cr⁶⁺ exceeded the risk tolerance standard of 10^-6 for carcinogenic hazards. The highest hazard levels were observed in Onsan and Mipo industrial complexes. In the case of non-carcinogenic hazards, Mn was identified as exceeding the hazard tolerance of 1, and it showed the highest hazard in the Ulsan Industrial Complex. Conclusions: This study presented a detailed health risk from exposure to heavy metals in PM_2.5 by industrial complexes located in Ulsan among five age groups. It is expected to be utilized as the basis for preparing damage control and industrial emission reduction measures against PM_2.5 exposure at the Ulsan Industrial Complex.

• Asian Journal of Atmospheric Environment
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• 제8권1호
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• pp.35-47
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• 2014

The purpose of the study is to evaluate the pollution level (gaseous and particle phase) in the public facilities for the PAHs, non-regulated materials, forecast the risk level by the health risk assessment (HRA) and propose the guideline level. PAH assessments through sampling of particulate matter of diameter < 2.5 ${\mu}m$ ($PM_{2.5}$). The user and worker exposure scenario for the PAHs consists of 24-hour exposure scenario (WIES) assuming the worst case and the normal exposure scenario (MIES) based on the survey. This study investigated 20 PAH substances selected out of 32 substances known to be carcinogenic or potentially carcinogenic. The risk assessment applies major toxic equivalency factor (TEF) proposed from existing studies and estaimates individual Excess Cancer Risk (ECR). The study assesses the fine dusts ($PM_{2.5}$) and the exposure levels of the gaseous and particle PAH materials for 6 spots in each 8 facility, e.g. underground subway stations, child-care facilities, elderly care facilities, super market, indoor parking lot, terminal waiting room, internet caf$\acute{e}$ (PC-rooms), movie theater. For internet caf$\acute{e}$ (PC-rooms) in particular, that marks the highest $PM_{2.5}$ concentration and the average concentration of 10 spots (2 spots for each cafe) is 73.3 ${\mu}g/m^3$ (range: 6.8-185.2 ${\mu}g/m^3$). The high level of $PM_{2.5}$ seen in internet cafes was likely due to indoor smoking in most cases. For the gaseous PAHs, the detection frequency for 4-5 rings shows high and the elements with 6 rings shows low frequency. For the particle PAHs, the detection frequency for 2-3 rings shows low and the elements with 6 rings show high frequency. As a result, it is investigated that the most important PAHs are the naphthalene, acenaphthene and phenanthrene from the study of Kim et al. (2013) and this annual study. The health risk assessment demonstrates that each facility shows the level of $10^{-6}-10^{-4}$. Considering standards and local source of pollution levels, it is judged that the management standard of the benzo (a)pyrene, one of the PAHs, shall be managed with the range of 0.5-1.2 $ng/m^3$. Smoking and ventilation were considered as the most important PAHs exposure associated with public facility $PM_{2.5}$. This study only estimated for inhalation health risk of PAHs and focused on the associated cancer risk, while multiple measurements would be necessary for public health and policy.

• 한국지하수토양환경학회:학술대회논문집
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• 한국지하수토양환경학회 2000년도 추계학술대회
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• pp.44-63
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• 2000

Situated close to Heathrow Airport, and adjacent to the M4 and M25 Motorways, the site at Axis Park is considered a prime location for business in the UK. In consequnce two of the UK's major property development companies, MEPC and Redrew Homes sought the expertise of Intergeo to remediate the contaminated former industrial site prior to its development. Industrial use of the twenty-six hectare site, started in 1936, when Hawker Aircraft commence aircraft manufacture. In 1963 the Firestone Tyre and Rubber Company purchased part of the site. Ford commenced vehicle production at the site in the mid-1970's and production was continued by Iveco Ford from 1986 to the plant's decommissioning in 1997. Geologically the site is underlain by sand and gravel, deposited in prehistory by the River Thames, with London Clay at around 6m depth. The level of groundwater fluctuates seasonally at around 2.5m depth, moving slowly southwest towards local streams and watercourses. A phased investigation of the site was undertaken, which culminated in the extensive site investigation undertaken by Intergeo in 1998. In total 50 boreholes, 90 probeholes and 60 trial pits were used to investigate the site and around 4000 solid and 1300 liquid samples were tested in the laboratory for chemical substances. The investigations identified total petroleum hydrocarbons in the soil up to 25, 000mg/kg. Diesel oil, with some lubricating oil were the main components. Volatile organic compounds were identified in the groundwater in excess of 10mg/l. Specific substances included trichloromethane, trichloromethane and tetrachloroethene. Both the oil and volatile compounds were widely spread across the site, The specific substances identified could be traced back to industrial processes used at one or other dates in the sites history Slightly elevated levels of toxic metals and polycyclic aromatic hydrocarbons were also identified locally. Prior to remediation of the site and throughout its progress, extensive liaison with the regulatory authorities and the client's professional representatives was required. In addition to meetings, numerous technical documents detailing methods and health and safety issues were required in order to comply with UK environmental and safety legislation. After initially considering a range of options to undertake remediation, the following three main techniques were selected: ex-situ bioremediation of hydrocarbon contaminated soils, skimming of free floating hydrocarbon product from the water surface at wells and excavations and air stripping of volatile organic compounds from groundwater recovered from wells. The achievements were as follows: 1) 350, 000m3 of soil was excavated and 112, 000m3 of sand and gravel was processed to remove gravel and cobble sized particles; 2) 53, 000m3 of hydrocarbon contaminated soil was bioremediated in windrows ; 3) 7000m3 of groundwater was processed by skimming to remove free floating Product; 4) 196, 000m3 of groundwater was Processed by air stripping to remove volatile organic compounds. Only 1000m3 of soil left the site for disposal in licensed waste facilities Given the costs of disposal in the UK, the selected methods represented a considerable cost saving to the Clients. All other soil was engineered back into the ground to a precise geotechnical specification. The following objective levels were achieved across the site 1) By a Risk Based Corrective Action (RBCA) methodology it was demonstrated that soil with less that 1000mg/kg total petroleum hydrocarbons did not pose a hazard to health or water resources and therefore, could remain insitu; 2) Soils destined for the residential areas of the site were remediated to 250mg/kg total petroleum hydrocarbons; in the industrial areas 500mg/kg was proven acceptable. 3) Hydrocarbons in groundwater were remediated to below the Dutch Intervegtion Level of 0.6mg/1; 4) Volatile organic compounds/BTEX group substances were reduced to below the Dutch Intervention Levels; 5) Polycyclic aromatic hydrocarbons and metals were below Inter-departmental Committee for the Redevelopment of Contaminated Land guideline levels for intended enduse. In order to verify the qualify of the work 1500 chemical test results were submitted for the purpose of validation. Quality assurance checks were undertaken by independent consultants and at an independent laboratory selected by Intergeo. Long term monitoring of water quality was undertaken for a period of one year after remediation work had been completed. Both the regulatory authorities and Clients representatives endorsed the quality of remediation now completed at the site. Subsequent to completion of the remediation work Redrew Homes constructed a prestige housing development. The properties at "Belvedere Place" retailed at premium prices. On the MEPC site the Post Office, amongst others, has located a major sorting office for the London area. Exceptionally high standards of remediation, control and documentation were a requirement for the work undertaken here.aken here.

• 항공우주정책ㆍ법학회지
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• 제33권1호
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• pp.227-260
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• 2018

최근 드론의 활용이 증가하면서 드론 기체의 파손 망실 손해 및 제3자의 신체 재산 피해 등 위험 역시 커지고 있다. 국내에서는 최근 드론 활용이 증가하면서 드론사고가 언론에 자주 보도되고 있다. 또한 시민 제보나 군 경찰의 처분의뢰 등을 통해 불법 사실을 인지하고 행정처분을 한 건수 역시 증가 추세이다. 드론사고로 인하여 제3자의 인적 물적 피해에 대한 손해배상책임 및 촬영정보유출 배상책임 등이 발생할 수 있다. 이에 따라 드론사고로 인한 책임과 위험을 완화할 수 있는 드론보험에 대한 고찰이 필요하다. 미국은 주택종합보험을 통해 주택에서 레저용 드론에 의해 발생하는 손해에 대해 보상받을 수 있다. 영국은 드론사고 발생 시 드론 소유자나 운영자가 무과실책임을 부담하게 된다. 또한 영국에서는 드론의 무게 및 운영 목적에 따라 드론보험 가입의무가 구분된다. 독일은 인적 물적 손해 발생 시, 드론 소유자는 드론이 항공기로 인정되는 한 무과실책임이 인정된다. 또한 독일에서는 드론 소지자에게 책임보험 가입의무를 부과하고 있다. 국내는 타인의 수요에 따라 유상으로 활용하는 초경량비행장치사용사업, 항공기대여업 및 항공레저스포츠업에 한하여 보험 가입을 의무화하고 있다. 이에 따라 자기 수요에 따라 활용되는 임무용 무인비행장치로 인한 제3자 손해 발생시, 원활한 손해배상에 어려움이 발생할 수 있는 상황이다. 외국 보험회사들은 드론으로 발생할 수 있는 다양한 손해를 담보하는 드론보험을 출시 판매하고 있다. 국내에서도 일부 보험사에서 드론 관련 제3자 손해배상보험 및 드론 기체 파손 망실 시 손해보전을 위한 기체보험을 개발하여 운영 중이다. 그러나 국내 드론보험은 합리적인 수준의 보험요율 산정을 위한 객관적인 자료 부족으로 인해 드론보험 요율이 매우 높은 실정이다. 또한 해킹 도난 분실 위험 및 기상영향 등 드론의 특수성을 반영한 드론보험 개발 역시 미흡한 실정이다. 드론 도입 활용 활성화 및 드론 활용 기관의 경제적 부담을 완화하기 위하여 드론보험 요율을 합리적인 수준으로 인하하는 것이 우선적으로 필요하다. 합리적인 수준의 보험요율을 산정하기 위해서는 보험사가 비행자료 등 기초자료를 확보하는 것이 선행되어야 하므로, 드론 시범사업을 통해 확보된 비행자료 등 기초자료를 보험업계와 공유하는 것이 필요하다. 또한 드론 활용으로 인한 제3자 손해 발생 시 원활한 배상을 위해 기체무게 활용분야 활용빈도 등 위험도를 고려하여 제3자 배상보험 가입을 제도화하는 방향에 대한 검토가 필요하다.