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        검색결과 77

        1.
        2023.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Passengers on public buses operating in the metropolitan area are exposed to the closed indoor air for minutes to hours. The indoor air quality of buses is mostly controlled through ceiling-mounted ventilation and filtration devices. A simulation study using a commercial code was conducted for fluid flow analysis to evaluate the potential effectiveness of an air purifier that can be inserted into bus windows to supply clean air from the outside to the inside. As a result of field measurements, the average CO2 concentration inside the bus during morning and evening rush hours ranged from 2,106±309 ppm to 3,308 ± 255 ppm depending on the number of passengers on board. This exceeded the Guideline for Public Transportation. The optimal installation position of an air purifier appeared to be the front side of the bus. In fact, even a low diffusing flow velocity of 0.5m/s was effective enough to maintain a low concentration of CO2 throughout the indoor space. Based on numerical analysis predictions with 45 passengers on board, the maximum CO2 concentration in the breathing zone was 2,203 ppm with the operation of an air purifier.
        4,200원
        4.
        2022.09 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Black carbon (BC), which is mainly contained in fine particulate matters, is one of the typical anthropogenic air pollutants that are generated from the incomplete combustion process and discharged into the atmosphere, and its various health effects particularly on children have been a growing concern. In this study, BC and particulate matters were closely analyzed in an elementary school adjacent to a high- traffic road in a large metropolitan city. The investigation showed that black carbon behaved similarly to ultrafine dust of 0.3 μm or less in the air, accounting for 20%-40% of it. The occurrence of high concentration outdoor pollution influences the BC content in indoor particulate matters. The average I/O value was 0.7 during the class-hours, and 0.8 without students. However, when students played in the classroom, the range of BC concentrations varied from 0.25 to 1.15, wider than 0.41-1.13 without students. Although this study was conducted with regard to just one elementary school, it can be considered to represent the typical air quality status of domestic schools, and it is believed to present valuable data which can be utilized to assist with preparing measures to enhance the air quality management of schools.
        4,000원
        5.
        2022.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        A field study was conducted to reduce airborne bacteria by supplying active ions to indoor spaces used by vulnerable human groups spending substantial amounts of time in places such as schools and hospitals. In an experiment conducted during school hours (8:00-15:00), the average number of airborne bacteria in classrooms was 345.53 CFU/m3 or more without active ions. However, ion supply reduced the airborne bacteria to an average of 113.23 CFU/m3, indicating an efficiency of 61.61%. As a result of tests in 33 rooms used for surgery in small and middle sized hospitals, ion supply for 2 to 4 hours reduced the average airborne bacteria concentration from 243.88 CFU/m3 to 104.34 CFU/m3, representing a 41.53% reduction. A laboratory test to confirm the ion activity has shown that the mortality rate of E. coli used as a test bacterium increased with exposure time to ions. The initial colony number of E. coli was 251 CFU, but decreased to 4 CFU after 60 minutes of exposure to active ions. Therefore, it was confirmed that the supply of active ions can contribute to the control of airborne bacteria in the indoor environment of schools, hospitals and other public facilities.
        4,000원
        6.
        2022.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The present study was conducted to examine the effect of soybean silage as a crude protein supplement for corn silage in the diet of Hanwoo steers. The first experiment was conducted to evaluate the effect of replacing corn silage with soybean silage at different levels on rumen fermentation characteristics in vitro. Commercially-purchased corn silage was replaced with 0, 4, 8, or 12% of soybean silage. Half gram of the substrate was added to 50 mL of buffer and rumen fluid from Hanwoo cows, and then incubated at 39°C for 0, 3, 6, 12, 24, and 48 h. At 24 h, the pH of the control (corn silage only) was lower (p<0.05) than that of soybeansupplemented silages, and the pH numerically increased along with increasing proportions of soybean silage. Other rumen parameters, including gas production, ammonia nitrogen, and total volatile fatty acids, were variable. However, they tended to increase with increasing proportions of soybean silage. In the second experiment, 60 Hanwoo steers were allocated to one of three dietary treatments, namely, CON (concentrate with Italian ryegrass), CS (concentrate with corn silage), CS4% (concentrate with corn silage and 4% of soybean silage). Animals were offered experimental diets for 110 days during the growing period and then finished with typified beef diets that were commercially available to evaluate the effect of soybean silage on animal performance and meat quality. With the soybean silage, the weight gain and feed efficiency of the animal were more significant than those of the other treatments during the growing period (p<0.05). However, the dietary treatments had little effect on meat quality except for meat color. In conclusion, corn silage mixed with soybean silage even at a lower level provided a greater ruminal environment and animal performances, particularly with increased carcass weight and feed efficiency during growing period.
        4,300원
        7.
        2022.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        We investigated the standard cultivation substrate for Sparassis latifolia “Neowul” bred in Jeollabuk-do Agricultural Research and Extension Services. Cultivation characteristics and yield were assessed by varying the kind of sawdust and additives, and the mixing ratio. The cultivation period in larch sawdust was the shortest at 97 days. The yield was excellent (143.6 g). The findings indicated that larch is a tree species appropriate for the cultivation of S. latifolia. When the additives were varied, the yield and productivity (53.1%) were highest (116.6 g) for the wheat bran treatment. Thus, wheat bran would be an additive appropriate for culturing S. latifolia. Concerning the use of different mixing ratios, larch sawdust:beet-pulp:wheat bran ratios of 80:15:5 and 85:10:5 resulted in yields of 114.4 g and 111.4 g, and productivity of 52.5% and 51.8%, respectively. These yield and productivity values were not statistically different. Thus, the standard cultivation substrate for S. latifolia can comprise larch sawdust, beet pulp, and wheat bran at a ratio of 80:15:5 or 85:10:5. The carbon/nitrogen (C/N) ratio assumed to be appropriate for the cultivation of S. latifolia was 184 –223. Pinheading would be difficult below a C/N substrate ratio of 105. Thus, the C/N ratio of the media, as well as the pH, would be vital factors affecting pinheading during S. latifolia cultivation.
        4,000원
        8.
        2022.03 KCI 등재 구독 인증기관 무료, 개인회원 유료
        CALMET (California Meteorological Model), which is a meteorological subroutine for an air quality dispersion mode (CALPUFF; California Puff Model), closely related with the land surface structure. In this study, the sensitivity of micro-meteorological parameters including wind speed and roughness height, Albedo, Bowen ratio, soil heat flux, and leaf area index were closely evaluated with change of land-use in relation to urban development. As a result, although no consistent dependence of roughness height on surface wind was found, it showed that high value of surface roughness could lead to the increase of friction velocity, influence the Monin-Obukhov length and the mixing height. At the same time, the increasing Albedo reduced friction velocity and mixing height. Thus, it was concluded for the CALMET modelling that it is necessary to first define the roughness height, Albedo, and Bowen ratio according to land-use.
        4,200원
        9.
        2021.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        In this study, indoor air quality indices (IAQI-C and IAQI-E) were developed for child care centers and elderly care centers based on health effects, and compared to the air quality index (CAI) for outdoor atmosphere. In addition, composite indices that integrate individual indices for each pollutant were developed to quickly and conveniently recognize the current air quality. Among all data, 71.2% and 35.6% belonged to the grades 'Good' and 'Moderate' for child care centers and elderly care centers, respectively. This assessment is more stringent than the CAI's criteria.
        4,000원
        12.
        2020.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        꽃송이버섯은 우리나라에서 2000년대 초반부터 재배를 시작하였고, 국내에서는 전라북도농업기술원이 육성한 ‘너울’이 2016년에 최초로 등록되어 있다. 그러나, 꽃송이버섯에 대한 재배매뉴얼이 없어 여전히 농가마다 자실체 생산성의 차이가 큰 실정이다. 이에 꽃송이버섯 ‘너울’의 발이조건을 구명하고 안정생산 기술을 개발하고자 배지 pH, 배지함수율, 종균접종량 조건에 따른 연구를 수행한 결과, 재배일수, 수확률과 자실체 중량을 고려한 연중 병당 수 량은 pH 3.8 처리구가 363.6 g으로 가장 높게 나타났으나 pH 3.6 조건에서는 수량이 189.5 g으로 급감하는 점, pH 4.0 조건이 배양일수가 짧고 pH 3.8 조건과 비교하여 재배일수가 같으며, 자실체 중량 차이의 유의성이 인정되지 않는 점, 농가에서 활용 시 정밀한 pH 조절이 어려운 점을 고려하여 pH 3.9±1로 조절하여 재배해야 안정생산이 가능할 것으로 판단된다. 아울러 배지함수율을 65%로 조절하고, 배지부피의 4%에 해당하는 액체종균을 접종 후 배양실 내 습도조건을 50% 이하로 설정하면 연중 병당 341.8 g을 생산할 것으로 판단된다.
        4,000원
        14.
        2019.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        In this study, we listed the VOCs focusing on ozone precursors emitted from printing shops in urban areas. The emission characteristics of the VOCs from workplaces were evaluated in terms of the used inks. As a result of field measurements, more than 80% of detected VOCs showed high values of photochemical ozone creation potential (POCP). The main species were aromatic hydrocarbons such as ethylbenzene, toluene, ethyltoluene, xylene, trimethylbenzene and their isomers, and paraffin hydrocarbons such as nonane, decane, and octane. Comparative examination between pristine ink and the printing process revealed the emission of hydrocarbons with 8 to 12 carbons such as o-xylene to n-dodecane from the used inks and with 3 to 7 carbons such as acetone to 3-methylhexane from the printing process. The major contributors to ozone production in printing industries were toluene (12.2%), heptane (7.43%), and 1,2,3-trimethylbenzene (7.21%) in every step.
        4,200원
        15.
        2019.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Recently, public complaints about unpleasant odor are increasing, particularly in urban areas. One of the odor sources is meat grilling restaurants in the vicinity of the residential areas. In this study, we characterized the odorous compounds generated from the stack of grilling restaurants, and evaluated the removal efficiency of the control facilities. As a result of the field investigation, the dilution index of the complex odor exceeded 500 times that of all test restaurants. The main substance was acetaldehyde. In addition, the correlation coefficient (R2) between the total odor and the sum of odor activity values (SOAV) was 0.73, a value high enough to indicate significant responsibility. The performance of the control facility has been shown to be strongly influenced by maintenance activities, such as cleaning and filter replacements.
        4,000원
        16.
        2019.04 KCI 등재 구독 인증기관 무료, 개인회원 유료
        국문 우주항공 분야에서 널리 쓰이고 있는 하이드라진[hydrazine, N2H4]은 로켓연료로 사용되는 대표적인 추진제이지만 환경에 유해하고 독성이 강하다는 단점이 존재한다. 따라서 친환경적이고 독성 이 적은 추진제가 다양하게 개발되고 있다. 본 연구에서는 수산화아민[hydroxylamine, NH2OH]을 출발물질로 하여, 질산[nitric acid, HNO3]과 산-염기 반응을 통해 얻어지는 친환경 추진제 HAN [hydroxylammonium nitrate, NH3OHNO3]의 물리 화학적 특성에 대하여 적외선분광법을 이용하여 합성물의 조성, 화학구조 및 작용기를 관찰하였고, 열중량분석을 통해 HAN의 분해온도를 확인하였다. 이온 크로마토그래피를 통해 합성한 HAN에 함유되어 있는 질산이온의 함량을 측정하였다. 즉, N-H와 N-O의 IR peak가 3161 cm-1와 1324 cm-1에서 각각 나타나는 것을 통해 생성한 화합물이 HAN임을 확인하였고, pH 5-7 근처에서 합성한 HAN은 분해온도가 120-140℃인 반면, pH 8 정도인 HAN은 분해온도가 14 0℃ 이상임을 알 수 있었다. 한편, pH 6-7 사이에서 HAN을 합성하였을 때, 가장 높은 질산이온의 농도는 70%인 것으로 나타났다.
        4,000원
        17.
        2018.09 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Cement production processes release various odor elements including acetaldehyde, hydrogen sulfide, formaldehyde and toluene etc. A three-dimensional numerical simulation using a commercial code of Computational Fluid Dynamics (CFD) was used to estimate the concentration profiles and dispersion distance around the local residential area. The calcination furnace, one of the main emission sources in the cement manufacturing process, discharged the odorous gases of H₂S, HCHO, CH₃CHO and C6H5CH₃at levels of up to 3.15 ppb, 5.1 ppm, 6.65 ppm and 0.74 ppm of H₂S, HCHO, CH₃CHO and C6H5CH₃respectively. This study found that as for the emission concentration of 1ppm for H₂S and CH₃CHO, the landing distance of the threshold value for each gas was extended in summer seasons at a low velocity. Low temperature of the flue gas at a high velocity also led to long dispersion.
        4,000원
        18.
        2018.03 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Alane(aluminum trihydride, AlH3)으로 명명되는 고에너지 물질인 삼수소알루미늄은 수소저장 물질로서 뿐만 아니라 우주항공분야의 고체 추진제나 방위산업의 화약제조용으로도 사용될 수 있다. 본 연구는 습식공정을 통하여 합성하고, 에테르를 세밀하게 분리하는 결정화 공정을 통하여 최종 수소화물을 추출하였다. 결정화 공정에서 삼수소알루미늄-에테레이트(AlH3·(C2H5)2O)가 alane으로 상변이하면서 입자가 성장하고, 85℃에서 2 시간의 결정화 시간이 이루어졌을 때 가장 안정된 결정상이 나타나는 모습을 확인하였다. 최종적으로 추출된 고체상 삼수소알루미늄은 막대모양의 γ-형태가 가장 많은 양을 차지하는 것으로 나타났으며, 크기는 50-100 μm 수준이었다
        4,000원
        19.
        2017.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        선박엔진에서 발생하는 NOx 및 SOx 제거용 스크러버 폐세정액에 포함되어 있는 저농도상 의 질산 및 황산이온을 비료상 물질로 회수하고자 하였다. 본 연구에서는 네 가지 유기용매를 적용하여 선택적으로 추출하여 회수하는 방법을 시험하였다. 아세톤과 메틸알콜을 이용하여 추출한 질산암모늄과 디에틸에테르와 에틸알콜을 적용한 황산암모늄의 시료를 적외석흡수분광법(IR)을 이용하여 분석한 결과, 상용제품과 거의 동일한 구성성분으로 나타났다. 이때 폐수로부터의 회수율은 최대 89%와 80%까지 각 각 얻을 수 있었다. 따라서 배기가스 스크러버에 잔존해있는 질산이온과 황산이온에 대한 회수는 사용하 는 용매의 선택도 및 용해도가 핵심적인 요소인 것으로 판단된다.
        4,000원
        20.
        2016.06 구독 인증기관 무료, 개인회원 유료
        본 논문은 Y3Al5O12:Ce3+(YAG:Ce3+) 단결정과 CaAlSiN3:Eu2+(CASN) 형광체에 관하여 연구하였다. 단결정은 floating zone법을 통해 성장시켰다. XRD 측정결과 JCPDS Card(#73-1370)에 상응하며 공간군 la-3d(230)에 속해있고 Cubic 구조로 된 것을 확인할 수 있었다. 단결정의 PL은 550 nm의 발광피크와 반치폭이 71 nm인 넓은 스펙트럼을 나 타냈고 PLE는 350 nm와 460 nm의 피크값을 나타냈다. CASN 분말의 PL은 604 nm, PLE는 460 nm의 피크값을 나타 냈다. CASN을 YAG:Ce3+ 단결정에 코팅하고 blue LED에 적용 후 측정한 결과, 측정한 PL 스펙트럼에서 CASN의 농도 증가에 따라 red shift 현상이 증가함을 알 수 있다. 연색성 또한 YAG:Ce3+ 단결정에서의 Ra는 67, CASN 10 wt%에서 는 78로 개선되는 것을 확인할 수 있었다.
        4,000원
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