• 청정기술
• /
• 제10권2호
• /
• pp.61-72
• /
• 2004

본 연구에서는 물성, 세정성, 헹굼액의 유수분리성을 고려하여 유기용매의 종류 및 함량, 계면활성제의 종류 및 함량, 부조계면활성제/계면활성제 (cosurfactant/surfactant, A/S) 비율 등의 변수로 하여 수계/준수계 세정제를 개발하였다. 개발된 세정제들은 대부분 평균 액적크기가 10 ~ 20 nm의 미세 나노입자를 형성 하였으며, 30.2~32.5 dyne/cm의 낮은 표면장력과 낮은 점도 값을 보여 주었다. 플럭스에 대한 용해력은 계면활성제의 소수성이 증가할수록 높게 나타났으며 terpene을 함유한 세정제들이 hydrocarbon 함유 세정제와 대응 시판세정제에 비해 우수한 용해력을 보여 terpene계 세정제가 대체세정제로의 적합성을 보여주었다. 또한, 개발된 세정제들을 함유한 헹굼액은 시판세정제에 비하여 우수한 유수분리성을 보여 헹굼액의 재활용이 가능하여 경제적인 부담과 수질오염을 줄일 수 있음을 보여주었다. 그리고 이렇게 개발된 세정제를 L 전자 회사의 전자부품 생산라인 SMT(surface mount technology) 세정공정에 적용시켜 보았다. 그 결과 solder cream 제거에 있어서 에탄올, 이소프로필알콜(IPA), glycol ether과 같은 물질이 함유된 기존의 세정제에 비하여 세정성능이 2 배이상 향상되었고 생산현장에서 악취와 VOC의 문제를 해결시킬 수 있었다.

• 한국농공학회논문집
• /
• 제46권5호
• /
• pp.141-153
• /
• 2004

Wetland system is widely accepted as one of natural water purification systems around the world for nonpoint sources pollution control. Constructed wetlands have become a popular technology for treating contaminated surface and waste water. In this study, the field experiment to reduce nonpoint source pollution loadings from polluted stream waters using wetland system was performed from June 2002 to March 2004. Four wetlands were used and the size of each one was 0.8ha. Water of Dangjin stream flowing into Seokmun estuarine reservoir was pumped into wetlands. Inflow and hydraulic residence time of the system was 500 $m^3$/day∼1,500 $m^3$/day, 2∼5 days, respectively. After 2 year operation, plant-coverage of the wetlauds was about 70% from bare soil surface at initial stage . Average water quality of the influent was $BOD_5$ 4.17 mg/L, TSS 18.45 mg/L, T-N 4.32 mg/L, and T-P 0.30 mg/L. The average removal rate of $BOD_5$, TSS, T-N and T-P during the study period was 5.6%, 46.6%, 45.7%, and 54.8%, respectively. Organic ($BOD_5$) removal rate was low and the reason might be low influent concentration. Wetland removal rate of T-P was about 10% higher than T-N. Performance of the experimental system was compared with existing data base (NADB), and it was within the range of general system performance. Overall, the wetland system was found to be adequate for treating polluted water stream with stable removal efficiency even during the winter period. Most of the nonpoint source pollutions from watershed are transported by streams or ditches, and they could be controled by constructed wetland system before entering the lake or reservoir.

• 설비공학논문집
• /
• 제8권3호
• /
• pp.397-412
• /
• 1996

This study aims to present the fundamental strategies to improve the Indoor Air Quality (IAQ) in apartment buildings. To investigate the concentration of indoor air pollutants such as radon, formaldehyde, and VOCs, both the document survey and the field measurement were conducted. In addition, to identify the source of the air pollutants, the laboratory experiment was carried out for various building materials. Finally, the minimum period to be reserved befor3e building occupation to ensure healthy IAQ, which largely depends on the ventilation rates, was simulated using a simple compuer program. The results of this study can be summarized as follows: 1. In case of newly-constructed apartment houses, concentrations of formaldehyde, VOCs and radon were found to exceed the standard. Meanwhile, at existing apartment houses, concentrations of VOCs, particularly toluene and xylene, highly exceeded the standasrd level. Concentrations of formaldehyde and radon, however, had been lowered according to the duration of occupation. 2. The laboratory experiment of concentration of pollutants per square meter of building material surface area showed that radon gas was much emitted from the gypsumboard; formaldehyde from flooring and wallpaper; and VOCs from paints and kitchen furnishings. The emission rates of formaldehyde and VOCs were proportional to air temperature. 3. According to the simulation of the minimum period to be reserved before occupation, newly-constructed airtight houses required about 190-200 days, and naturally ventialted houses with fully-open-windows required about 20-45days, in order to keep the level of radon gas lower than standard. Therefore, with the current practice, the date of occupation should be delayed for about 15 days.

• 한국토양비료학회지
• /
• 제9권2호
• /
• pp.71-76
• /
• 1976

1. 개량제(改良劑) 시용(施用)에 의(依)한 상엽수량(桑葉收量)의 증수율(增收率)은 표준구(標準區)에 비(比)하여 20~80%이었으며 개량제(改良劑) 처리간(處理間)의 효과(効果)는 고토질석회(苦土質石灰)>퇴비(堆肥)>용성인비(溶成燐肥)>녹비재배(綠肥栽培) 및 환원(還元)>맥간구(麥稈區)의 순위(順位)이었다. 2. 상엽수량(桑葉收量)과 가장 상관도(相關圖)가 높은 생태적요소(生態的要素)는 근중(根重)과 근권체적(根圈體積)이며 그다음으로 지조장(枝條長)과 지조수(枝條數)이었다. 또한 토양(土壌) 및 상엽중(桑葉中)의 Ca과 Mg함량(含量)과 상엽수량(桑葉收量)과는 높은 상관(相關)을 보였다. 3. 지조선단(枝條先端)의 고사현상(枯死現象)은 엽중(葉中) $K_2O$와 MgO함량(含量)의 불균형(不均衡)의 영향(影響)으로부터 오며 상엽중(桑葉中) $K_2O/MgO$의 비(比)가 6.0 또는 그이상(以上)되어야 고손율(枯損率)을 최소(最少)로 할 수 있었다. 4. 토지상전조성(土地桑田造成)을 위(爲)하여는 유기물외(有機物外)에 고토(苦土)를 포함(包含)한 석회질비료(石灰質肥料) 시용(施用)이 필수적(必須的)이나 이들만의 시용(施用)은 고손율(枯損率)을 증가(增加)시키므로 상대적(相對的)으로 가리(加里)의 증시(增施)가 병행(併行)되어야 함을 알았다.

• 공학교육연구
• /
• 제3권1호
• /
• pp.84-91
• /
• 2000

현대는 시스템화되고 융합화되어가는 시대이다. 시스템이 다른 시스템과 모여 융합되고, 이들이 다시 커다란 형태의 시스템으로 융합되어 다시금 하나의 거대한 시스템이 되곤 한다. 전자소자는 개별소자시대를 지나 소자들이 융합되어 시스템으로 통합되는가 하면 반도체집적화로 시스템화되고 있다. 이 연구는 전자공학 2년제 교육과정을 시대에 따라 시스템 및 반도체 설계 특성화의 방향으로 모듈화하고 학제간의 유기적인 융합을 고려하여 재구성하였다. 이 교육과정은 다학기제의 모듈화 모델로 개발하여 산학연계 현장교육 및 심화교육 등을 가능토록 개발하였다.

• 한국지하수토양환경학회지:지하수토양환경
• /
• 제24권6호
• /
• pp.16-25
• /
• 2019

Anthropogenic polycyclic aromatic hydrocarbons (PAHs) are formed by the incomplete combustion of fuels and industrial waste. PAHs can be widely exposed to the environment (water, soil and groundwater). PAHs are potentially toxic, mutagenic and/or carcinogenic. Fundamental studies such as biota uptake (e.g., earthworm and plant) of PAHs are highly needed. It is necessary to develop alternative ways to evaluate bioavailability of PAHs instead of using living organisms because it is time-consuming, difficult to apply in the field, and also exaction method is tedious and time-consuming. In this study, sorption behaviors of phenanthrene were evaluated to predict the fate of PAHs in soils. Moreover, bioaccumulation of PAHs in an artificially contaminated soil was evaluated using pea plant (Pisum sativum) as a bioindicator. A novel passive sampler, organic-diffusive gradient in thin-film (o-DGT) for PAHs was newly synthesized, tested as a biomimic surrogate and compared with plant accumulation. Sorption partitioning coefficient (K_P) and sorption capacity (K_F) were in the order of natural soil > loess corresponding to the increase in organic carbon content (f_oc). Biota-to-soil accumulation factor (BSAF) and DGT-to-soil accumulation factor (DSAF) were evaluated. o-DGT uptake was linearly correlated with pea plant uptake of phenanthrene in contaminated soil (R²=0.863). The Tenax TA based o-DGT as a biomimic surrogate can be used for the prediction of pea plant uptake of phenanthrene in contaminated soil.

• 한국토양비료학회지
• /
• 제49권6호
• /
• pp.795-806
• /
• 2016

This study was conducted to improve the continuous techniques for international competitiveness of ginseng industry to Korea-China FTA negotiation and conclusion, and provide the basic information for ginseng industry development of Korea. It was carried out the visiting of the northeastern three provinces (Jilin, Liaoling and Heilongjang) in China for 3-year from 2014 to 2016 and observed the farmers' fields of ginseng cultivation with soil environmental status. The types of ginseng cultivation could be observed in small scales of 0.5~3.0 ha, in middle scales of 4.0~10.0 ha and in large scales of 30~700 ha with the kinds of imhasam, Chinese ginseng, Korean ginseng and western ginseng. Also ginseng was cultivated in newly reclaimed land of forest in two types of direct seeding and transplanting of ginseng seedlings. The field beds of ginseng growing were covered with vinyl films in arch design of 100~130 cm height and vinyl was painted in spraying with blue, green and yellow colours for shading. It was investigated in status of the physico-chemical properties of soils. The physical information on the field soils were silt loam, loam and sandy loam in soil textures, and some plain in low slope, some alluvial fan or local valley in forest of land topography. Soil pH ranged within 5.0~5.2, soil EC was $0.93{\sim}3.78dS\;m^{-1}$, organic matter was $37{\sim}35g\;kg^{-1}$, nitrate nitrogen $63{\sim}490mg\;kg^{-1}$, available $P_2O_5$ $55{\sim}163mg\;kg^{-1}$, and in exchangeable cations, K was 0.30~0.98, Ca was 6.5~14.0, Mg was $1.1{\sim}5.3cmol_c\;kg^{-1}$ in ranges. Farmers used the fertilizer for ginseng cultivation in 10~11 t of compost, $200{\sim}400kg\;ha^{-1}$ of complex fertilizer and $750kg\;ha^{-1}$ of oil cakes. The northeastern three provinces of China can use the newly lands with large areas of ginseng cultivation in soil sickness by continuous cropping. and the soil basic fertility is batter than that of Korean in standard guide of ginseng cultivation soil.

• 한국잡초학회지
• /
• 제1권1호
• /
• pp.5-14
• /
• 1981

Weed is one of the problems in the crop land as well as in uncultivated land, raising the farm management costs. Therefore, the weed control is essential for effective agricultural management. The cost for weed control in Korea occupies on the average 27.6% of the total labor cost required. Agricultural policies since 1960 were transferring from yield increase due to land productivities to increase of income due to labor productivities. Therefore, the weed control by hand is also changed to weed control by chemicals. The weed control by chemicals has also brought about some side-effects and needs better, improved weed control methods. The present weed control situation and related problems were studied to present new approaches for agricultural development in the future. There were 458 species of weeds in 82 families which were growing in the crop land. The weeds to control, however, are 12 in paddy field and 9 in upland. So far weeds in paddy field are well under control, while weeds in upland are poorly controlled due to change in chemical efficiency and chemical damage in the upland. The administration, research and extension work for the efficient use of agricultural chemicals have been done by various institutions, such as Office of Rural Development, Office of Forestry, and chemical companies. The courses for agricultural chemicals were offered in the agricultural colleges. However, the efficiency of chemicals could not be maximized due to the poor relationships among related institutes. The newly established Agricultural Chemical Research Center at the Office of Rural Development and the Korean Weed Science Association are expected to contribute toward improving weed control in Korea. The Korean agriculture in the future will eventually be mechanized and the varieties resistant to high nitrogen application and to high plant density will be required for high yields. The rice will be transplanted earlier and the whole growing period will be extended. The application of organic matter will be increased for increasing soil fertility, and the use of agricultural chemicals will be continued. Under such a condition, the studies on the weed occurrence and its integrated control measures will be needed. Also weed controls in the newly exclaimed land, crop varieties, horticultural varieties, forage crops, and forests are also needed to study. Basic and practical researches for the weed control to improve the labor productivity will be also needed. In order to meet the all requirements for efficient weed control, weed control systems including all the academics, research and extension workers, administratives, farmers and companies should be established. Also securing researchers and education of personnels are pre-required and research funds for the chemical studies should be provided efficiently and timely.

• 한국농공학회논문집
• /
• 제47권1호
• /
• pp.79-91
• /
• 2005

Wetland systems are widely accepted natural water purification systems around the world in nonpoint sources pollution control. Constructed wetlands have become a popular technology for treating contaminated surface and wastewater. In this study, the field experiment to reduce nonpoint source pollution loadings from polluted stream waters using wetland system was performed from June 2002 to March 2004, including winter performance using four newly constructed wetlands. The Dangjin stream water flowing into Seokmun estuarine lake was pumped into wetlands, and inflow and hydraulic residence time of the system was $500m^{3}{\~}1500m^{3}/day\;and\;2{\~}5$ days respectively. After 3 years operation plant-coverage was about $80~90\%$ from zero at initial stage even with no plantation. Average water quality of the influent in growing season was BOD_{5}\;3.96mg/L$, TSS 22.98 mg/L, T-N 3.29 mg/L, T-P 0.30 mg/L. The average removal rate of four wetlands for $BOD_{5},\;TSS,\;T-N\;and\;T-P$ in growing season was $24\%$, $62\%$, $54\%$, and $51\%$, respectively. And average water quality of the influent in winter season was $BOD_{5}$ 4.92 mg/L, TSS 12.47 mg/L, T-N 5.54 mg/L, and T-P 0.32 mg/L, respectively. The average removal rate of four wetlands for them was $-21\%$. $23\%$, $33\%$, and $53\%$, respectively. The reason of higher BOD_{5} effluent concentration in winter season might be that low temperature restrained microorganism activity and a organic body from the withered plant and algae was flown out. Except the result of $BOD_{5}$, the effectiveness of water quality improvement in winter season was satisfactory for treating polluted stream waters, and $BOD_{5}$ variation was within the range of background concentration. Performance of the experimental system was compared with existing data base (NADB), and it was within the range of general system performance. Overall, the wetland system was found to be satisfactory for NPS control such as improvement of polluted stream water.

• 한국토양비료학회지
• /
• 제27권2호
• /
• pp.105-110
• /
• 1994

신개간지(新開墾地)에서 몇가지 물리화학적인 개량방법(改良方法)을 병행(竝行)하여 실시하여 년차간에 토양특성 변화와 율무의 수량을 조사하여 토양개량과 율무재배에 대한 기초자료를 얻고자 신개간지에서 율무를 1955년부터 4년간(年間) 재배하면서 율무수량과 토양(土壤)의 변화량과 변화율(變化率)을 조사, 분석한 결과는 다음과 같다. 1. 토양의 용적밀도(容積密度)나 경도(硬度)는 표토(表土)에서 3년차까지 계속 낮아지다가 개량제 시용이 없었던 4년차에는 높아졌다. 토양산도는 토심이나 년차간에 큰 차이가 없었다. 2. 율무수량(收量)은 종합개량처리(綜合改良處理)가 평균(平均) 2.16ton/ha로 가장 많고 대조구(對照區)에 비하여 49% 증수(增收)되었으며 다른 처리구의 수량은 심경구(深耕區)>인산구>석회구>퇴비구>대조구(對照區) 순(順)으로 많았다. 3. 연차간(年次間) 율무수량과 토양의 물리화학성과의 상관계수(相關係數)는 토양산도와 유기물 함량이 가장 높았고 표토(表土)보다는 심토(心土)에서 유의성이 높았다. 4. 토양의 물리화학성 변화율(變化率)과 율무수량(收量)과의 상관관계는 토양의 용적밀도와 경도가 가장 높았고 토양 화학성중에서는 표토(表土)에서 토양산도(土壤酸度)만이 유의성이 있었다.