• 식물병연구
• /
• 제21권3호
• /
• pp.231-234
• /
• 2015

Elsinoe fawcettii and E. australis are two currently recognized scab pathogens of citrus. E. fawcettii has at least six pathotypes while E. australis has at least two pathotypes. Colonies of E. fawcettii and E. australis do not sporulate in artificial media including potato dextrose agar (PDA). Whiteside's method has been widely used for preparing conidial inoculum in vitro. This study was carried out to develop efficient method for conidia production from artificial media. We developed a shaking method which included the following steps: 1) Colony grown on PDA was mashed with a steel spatula; 2) Mycelia fragments were cultured in 50 ml sterilized rain water in a rotary shaker-incubator (180 rpm) at $25^{\circ}C$ for 24 h: 3) The conidia suspension was filtered through two layers of cheesecloth. Average conidia production of all isolates tested using this shaking method was approximately 13.1 times higher than that from Whiteside's method in this study.

• 산업기술연구
• /
• 제29권A호
• /
• pp.55-60
• /
• 2009

Stabilization treatment is one of processes for wastes and their components to reduce their toxicity and migration rates to surroundings. Inorganic binders such as calcium hydroxide, blast furnace slag and red mud were tested for their potential applicability to in-situ stabilization of heavy metal contaminated tailings in the abandoned metal mines. Columns(150mm dia. ${\times}$ 450mm length) filled with mixtures of inorganic binders and tailing from the Geumjang mine with various mixing ratios of binders to tailings, 5%, 7% and 9% were applied artificial rainfall tests for 28 days. Effluents from columns filled with calcium hydroxide and tailing showed high pH's of ~12.5 and a increasing trend of concentration in Pb and Zn with a significant decrease in permeability in terms of elapsed days. Those with burning slag and tailing showed pH's of ~8.5 and significantly low concentrations in heavy metals with a stable permeability. In case of red mud, effluents showed significantly low concentrations in heavy metals but a decreased permeability with pH's of ~10.5. Conclusively, this basic study suggests burning furnace slag be a potential stabilizer for effective treatment of heavy metal contaminated mine tailings.

• 한국산림과학회지
• /
• 제76권1호
• /
• pp.11-16
• /
• 1987

잣나무 유묘(幼苗)와 쥐똥나무 삽목묘(揷木苗)를 인공산성우(人工酸性雨)로 처리(處理)하고 엽내(葉內) 엽록소(葉綠素) a와 b의 함량(含量)을 분석(分析)하여 양(量)의 증감(增減)에 따른 산도(酸度) 수준(水準)의 영향(影響)을 논의(論議)하였다. 처리(處理)된 시험수종(試驗樹種)은 1985년(年) 봄에 pot에 재배(栽培)되고 해당지역(該當地域)의 30년간(年間)의 강우(降雨) 양식(樣式)을 모의(模擬)해서 산성우(酸性雨)(pH 수준(水準) 6.5, 4.0 및 2.0)를 5월(月)부터 8월(月)까지 4개월간(個月間)에 걸쳐 살포(撒布)하고, 동년(同年) 9월(月) 18일(日) 성숙(成熟)된 엽(葉)을 채취(採取)하여 엽중(葉中)의 엽록소(葉綠素)를 분석(分析)하였다. 분석(分析) 결과(結果)에 의(依)하면, 양(兩) 수종(樹種) 공통적(共通的)으로 산성우(酸性雨)의 산도(酸度)가 강(强)해짐에 따라 엽록소(葉綠素) a와 b의 함량(含量)은 감소(減少)하는 경향(傾向)을 보였고. 엽록소(葉綠素) a에 있어서는 감소(減少) 경향(傾向)이 통계적(統計的)으로 유의(有意)했고, 엽록소(葉綠素) b의 경우(境遇)는 유의(有意)하지 않았으나 감소(減少) 경향(傾向)이 있는 것으로 받아들일 수 있었다. 산성우(酸性雨)의 pH 수준(水準)에 따른 엽록소(葉綠素) a와 b에 대한 감소(減少) 효과(効果) 차이(差異)에 있어서는 양(兩) 수종(樹種) 모두 pH 수준별(水準別)로 감소(減少) 지수(指數)가 유사(類似)하였으며, 따라서 엽록소(葉綠素) a 대(對) b의 함량비(含量比)는 산성우(酸性雨)의 pH 수준(水準) 여하(如何)에 불구(不拘)하고 일정(一定)한 값을 유지(維持)하고 있었다.

• Corrosion Science and Technology
• /
• 제8권1호
• /
• pp.40-43
• /
• 2009

We investigated the corrosion resistance of Zn and Cu coated steel pipes as a substitute for Cu pipe in an air-conditioner system. In addition, the galvanic corrosion tendency between two dissimilar metal parts was studied. The corrosion resistance of the Cu electroplated steel was similar to that of Cu, while the corrosion rate of the Zn electro- galvanized and the galvalume (Zn-55 % Al) coated steels was much higher and not suitable for Cu substitute in artificial sea water and acidic rain environments. Furthermore, the galvanic difference between Cu electroplated steel and Cu was so small that the Cu coated steel pipe can be used as a substitute for Cu pipe in an air-conditioner system.

• 한국전기전자재료학회:학술대회논문집
• /
• 한국전기전자재료학회 2004년도 춘계학술대회 논문집 방전 플라즈마 유기절연재료 초전도 자성체연구회
• /
• pp.65-68
• /
• 2004

This paper researched leakage current characteristics of artificially contaminated EHV insulators through construction of long-term testing facility. Insulators were contaminated and classified into the ESDD contaminated levels under IEC standards method. As the test results of contaminated insulators was carried out several experiments, leakage current greatly increased during initial rainfall. After contaminated insulators were naturally washed by rain, leakage current was not increased.

• 한국전기전자재료학회:학술대회논문집
• /
• 한국전기전자재료학회 2004년도 하계학술대회 논문집 Vol.5 No.2
• /
• pp.1166-1170
• /
• 2004

The leakage currents of transmission insulator were investigated as a function of environmental conditions, such as temperature, humidity, and rainfall. The insulators were artificially contaminated with insoluble yellow soil and kaolin which helped salt to stick on the surface of insulator. The insulators contaminated with the grade of B, C, and D were installed in the KoChang Testing Center. The leakage currents were measured and compared with non-contaminated insulators. The results indicated that the most important factor affecting leakage current was humidity. After heavy rain, the artificially contaminated salt was dissolved, resulting in similar characteristics between with and without contamination

• 콘크리트학회지
• /
• 제8권1호
• /
• pp.138-144
• /
• 1996

현재 우리나라 교량의 겨우 상판의 열화현상을 극소화시키기 위하여 방수의 필요성이 절대적으로 요구되고 있다. 따라서 본 연구에서는 지금 현재 국내에서 시공되고 있는 교량 방수 공법 중 침투성 방수제를 실내실험을 통하여 자연적 및 인위적 조건에 저항하는 특성의 파악을 위한 실험을 수행하였다. 실험결과 방수제의 침투깊이의 감소로 인해서 고강도 콘크리트를 사용할 경우 이 공법의 적용은 재고할 필요가 있는 것으로 판단된다. 방수제를 사용하는 경우 콘크리트의 내산성이 우수하게 나타나므로 침투성 방수제는 산성비에 대한 저항성이 크다. 그러나 방수제의 성능은 자연상태로 노출되어 있는 경우 그 수명이 영구적이 아니므로 교량의 슬래브에는 반드시 아스팔트 콘크리트를 포장하여야 한다. 실험결과로 부터의 또다른 결론은 방수제로 인해 콘크리트의 내열성 및 내마모성이 증가됨을 알 수 있다.

• Wind and Structures
• /
• 제26권4호
• /
• pp.215-229
• /
• 2018

The appearance of a rivulet at the upper surface of a stay cable is responsible for rain-wind-induced vibration (RWIV) of cables of cable-stayed bridges. However, the formation mechanism of the upper rivulet and its aerodynamic effects on the stay cable has not been fully understood. Large eddy simulation (LES) method is used to investigate flow around and aerodynamics of a circular cylinder with an upper rivulet at a Reynolds number of 140,000. Results show that the mean lift coefficients of the circular cylinder experience three distinct stages, zero-lift stage, positive-lift stage and negative-lift stage as the rivulet located at various positions. Both pressure-induced and friction-induced aerodynamic forces on the upper rivulet are helpful for its appearance on the upside of the stay cable. The friction-induced aerodynamic forces, which have not been considered in the previous theoretical models, may not be neglected in modeling the RWIV. In positive-lift stage, the shear layer separated from the upper rivulet can reattach on the surface of the cylinder and form separation bubbles, which result in a high non-zero mean lift of the cylinder and potentially induces the occurrence of RWIV. The separation bubbles are intrinsically unsteady flow phenomena. A serial of small eddies first appears in the laminar shear layer separated from the upper rivulet, which then coalesces and reattaches on the side surface of the cylinder and eventually sheds into the wake.

• 한국응용곤충학회지
• /
• 제19권1호
• /
• pp.39-44
• /
• 1980

배나무 붉은별무늬병은 1973년이래 해마다 발병이 증가하여 1975연에는 발병엽율 $60.3\%$에 달하였으며 1974년 향나무 재식규제조치이후 감소하였다. 붉은별무늬병원균의 동포자발아 시기는 4월중순부터 5월중순까지 였으며 인공강우에 의하여 그 발아시기를 5일 전에 알 수 있었다. 성숙한 동포자퇴의 포자발아에는 3시간 이상의 계속되는 비로서 상당량의 강수가 필요하였다. 배나무의 감염은 강우중이나 강우직후에 이루워지고 있었으며 강양 24시간 이후의 감염은 없었다. 감염후 배나무에서의 잠복기간은 $9\~10$일이었다. 배나무와 향나무사이의 지리가 100m 이내인 경우에는 거의 모든 배나무가 발병하였으나 거리가 멀어짐에 따라 발병율도 감소하였으며 2km 이상에서는 발병이 없었다.

• 한국환경과학회지
• /
• 제19권2호
• /
• pp.229-236
• /
• 2010

As air pollution has emerged as one of the most pressing urban environmental concerns, many studies have investigated the influence of air pollutants(ex: $O^3$, $NO^2$, $SO^2$, Acid rain, etc.) on roadside trees and urban grove. In Korea, population density started to increase since the industrialization. Since dense population aggravates our living conditions, it's very important for us to preserve and keep a lively and refreshing nature in order to live with green nature in harmony under the current artificial environment-dominating world. In metropolitan cities, the production of pollutants increases in proportion to population growth. The vehicle exhaust gas and air pollutants from cooling and heating systems have been the major causes of acid rain. Furthermore, tire particles which are naturally produced by tire wearing on roads and other toxic substances in exhaust gas have caused a problem in human health directly and indirectly. In fact, a lot of studies have analyzed air pollution, roadside trees and plants in Korea. However, they are mostly limited to covering the influence of air pollution on the growth of plants. No paper has clearly explained why air pollution-resistant or-vulnerable species has shown different reactions yet. Even though a lot of urban roadside trees have died or stopped to grow from time to time, this kind of problem has not been properly examined. This paper is aimed to comparatively analyze physio-ecological characteristic such as photosynthesis, chlorophyll contents, soil volume water figure out their relationship with environmental factors against the expanding roadside trees in Cheong-ju, and provide basic data for management of roadside trees and elaboration of urban environment preservation policies.