• Korean Journal of Soil Science and Fertilizer
• /
• v.25 no.4
• /
• pp.334-341
• /
• 1992

The effects of the various pattern of paddy-upland switching system on rice yield and the nutrient absorption characteristics were examined in the paddy field of Seokcheon silty soil for three years from 1989 to 1991. The obtained results of the two years from 1990 to 1991 are as follows : 1. Rice grain yields were high in the order of potato-cabbage>soybean>continuous paddy plot for the second and third year. Among the rice yield components the numbers of grains per panicle and the rate of ripening grain exerted the yield increase. 2. The contents and absorption amounts of nutrient in harvested straw plant increased with the incease of rice yields during the second and third year(1990~1991). The amounts of all nutrient absorption increased with the increased level of nitrogen fertilization at the third year(1991). 3. The periodical change of leaf green color was responded well with the content of ammonia concentration of soil solution.

• Korean Journal of Soil Science and Fertilizer
• /
• v.16 no.4
• /
• pp.325-332
• /
• 1983

To investigate interactions of silicate and phosphate applied in paddy soil, different levels of the two fertilizers were treated on pots of Jinheung variety of Japonica rice, then availability and absorption of the silicate and phosphate and growth of the rice plant were analyzed. The availability of silicate applied in soil was reduced by increased application of phosphate and this antagonism implied the interaction of silicate and phosphate in soil. The silicate absorption by rice plants was remarkably reduced by the phosphate application, while the phosphate absorption was reduce only at high levels of silicate. At low levels of silicate, the phosphate absorption was affected differently depending on growth stage or parts of the rice plant. The application of silicate fertilizers increased the pH of the soils. The application of silicate and phosphate fertilizers improved the plant height, the tiller number, and the grain weight, but not the dry weight of the grain. The effect of interaction of silicate and phosphate on the plant growth did not appeared.

• Korean Journal of Soil Science and Fertilizer
• /
• v.6 no.1
• /
• pp.17-26
• /
• 1973

A survey on nutrient recovery by rice plant was carried out countrywide in 1967 and 1968. The relationships between percent recovery of fertilizer nutrient and climatic zone or deposition mode, drainage grade, and texture of paddy soil profile, or chemical characteristics of surface soil were as follows. 1. The percent recovery of fertilizer nitrogen was highest in south and least in north, and that of potassium was highest in south and least in middle climatic zone. 2. Since the percent recovery of Phosphorus variates yearly with climatic zone, mode of deposition drainage grade or soil texture, it seemed to depend greatly on soil-weather interaction. 3. Nitrogen recovery was highest in alluvial colluvial (AC) and it was followed by alluvial (A), fluvomarine (FM) and old alluvial in decreasing order while potassium recovery was OA>AC>A>FM. 4. The greater the drainage was, the higher the nitrogen recovery. The recovery of potassium and phosphorus tended to show high in moderately well drain, and low in poorly and well drain. 5. Nitrogen recovery was highest in fine silty and gradually decreased with coarseness. That of potassium or phosphorus was greater in those below fine loamy than in those above coarse silty. 6. Nitrogen recovery was high in Jisan, Geugrag, and Sindab series, and low in Hwadong, Gyuam, Yongji and Hwabong series. 7. Nitrogen recovery showed significant positive correlation with the content of organic matter (OM), Ca, CEC of surface soil and only in the year of high phosphorus recovery it had significant negative correlation with soil phosphorus. Phosphorus recovery had significant posititive correlation with CEC, Mg or Ca. 8. Potassium recovery showed negative correlation with K/(Ca+Mg), P, OM or K while positive correlation with Ca, Mg, CEC but significant only with K/(Ca+Mg) in the year of low potassium recovery. In the year of high K recovery it showed positive correlation with P, OM, K/(Ca+Mg) or K while negative with CEC, Mg or Ca but significant only with P, OM or CEC. Soil potassium has significant positive correlation with soil OM and P only in the year of low potassium recovery. 9. The percent recovery of N, P or K showed negative correlation coefficient with pH without significant. 10. There was significant positive correlation between OM and P, K or K/(Ca+Mg), P and K or K/(Ca+Mg), K and K/(Ca+Mg), Mg or CEC, Ca and K/(Ca+Mg), Mg, CEC or pH, Mg and CEC while significant negative correlation between Mg and OM, P or K/(Ca+Mg), P and CEC, Ca and K/(Ca+Mg). 11. From the percent rcovery of fertilizer and soil chemical characteristics it was known that soil organic matter increase nitrogen uptake, that K uptake has closer relation to K/(Ca+Mg) than K, that Mg affects P ugtake, and that the annual difference of P and K recovery was partly explainable.

• Journal of Korean Society of Water and Wastewater
• /
• v.19 no.4
• /
• pp.462-472
• /
• 2005

This study was carried out to suggest the plans for installation of rural sewage treatment facilities through the analysis of these facilities installed in Chungchongnam-do Province. About 5% of all installation was carried out by the department of wastewater and related environment problems and the other case was carried out by the department of construction or residence. In wastewater caused by 250 and 300 persons, facilities capacity do not exceed about $50m^3/d$, caused by 2,500 and 3,000 persons, $500m^3/d$. Advanced sewage treatment process were first needed in the discharge area where affected the water environment greatly. However, in carrying out the water quality pollutant of the total amount management system in the other areas, they should be driven only over the scale of pollutant quota object facilities standard. Rural sewage must be included in the special accounts according to the regulations of local government, and sewage treatment cost should be collected to manage. Installation type uses integrating joint treatment method in case the distance among villages is short or one treatment facility independently.

• Proceedings of the Korean Vacuum Society Conference
• /
• 2016.02a
• /
• pp.203.2-203.2
• /
• 2016

미생물이 스스로 생성한 고분자 물질에 싸이며 군집체를 형성한 바이오필름은 고체 표면에 부착되며 우리 생활 속에 다양한 형태로 발견할 수 있다. 바이오필름은 미생물에 적합하지 않은 외부 환경으로부터 미생물 스스로 보호하는 기능을 하며, 형성된 바이오필름은 오랜 기간 동안 생존하여 살균제나 항생제로부터 저항성을 가져 살균과정에서 제거되지 않고 2차오염을 야기할 수 있어 식품 가공 기계 및 수도관, 의료기기 등에 형성되었을 경우 식품 오염, 상처 감염 등의 원인이 된다. 이 때문에 위생과 바이오필름의 상관관계를 인지하고 이를 제어하기 위한 연구가 여러 방법으로 진행되고 있다. 대표적인 방법으로는 천연 향균제 개발, 쿼럼 센싱(Quoroum sensing)과 같이 미생물의 신호전달 체계를 차단하는 물질 개발 및 플라즈마 처리 등이 있다. 본 연구에서는 격자형식의 유전장벽방전(DBD) 형식의 플라즈마 소스를 개발하여 바이오필름의 효과적인 제어 가능성을 확인하고, 제어 방식의 관계를 파악하였다. 플라즈마 처리 대상의 화학적 분석을 위하여 유기물질 등을 사용해 플라즈마 처리수 내 화학물질 분석 시스템을 구축하여 이를 기반으로 플라즈마로 생성된 HNO2, NO2-, H2O2 등의 화학종이 가지는 바이오필름 제어 관계를 살펴보았으며, 화학적 방법인 제어효과와 비교하여 플라즈마의 바이오필름 제어 특성에 대해 살펴보았다. 본 발표에서 플라즈마의 바이오필름 제어효과에 대한 분석에 대해 더 자세한 결과가 발표될 예정이다.

• Journal of Korean Society of Water and Wastewater
• /
• v.26 no.6
• /
• pp.871-881
• /
• 2012

This study suggested a model that can predict a degradation condition over time of two plastic pipes, PE and PVC, which are currently used in the country. This study was analyzed physical characteristics change of plastic pipes by comparison with initial physical characteristics (on the case of new pipes). Since this is dependent on accidents that already occurred, there are limitations that it only decides a priority on improvement based on relative corrosion status rather than precautionary aspects. The comparison results between physical degradation by the deducted performance rating and a conventional numerical scoring method showed that correlation coefficient was 0.67 for PE pipes and 0.86 for PVC pipes, indicating a high correlation. According to this result, it has been decided that the performance rating suggested herein can be applied naturally to the criterion of an improvement decision, which was based on Scoring System. From results of the research, it is expected that a reliable result can be provided to an improvement decision process related to degradation of plastic pipes by comprehensively comparing and evaluating a condition of pipe materials(direct factors) and an environmental impact(indirect factors).

• Journal of Korean Society of Water and Wastewater
• /
• v.8 no.1
• /
• pp.34-43
• /
• 1994

It is well known that the adsorption character of activated carbon is dependent on the specific surface area and pore volume, but the relationship between the surface-chemical structure and the adsorption character has not been studied very often. The purpose of this study is to investigate the effect of the acidic surface functional groups of activated carbon and the adsorption characteristics of low concentration phenol. So three types of activated carbons and four different treatments were introduced to this isotherm experiment. These treatments were nontreatment, 1N $HNO_3$ treatment, 6N $HNO_3$ treatment, $H_2O_2$ treatment. The conclusions of this study are as followings. If the initial concentration of phenol is high as 5mg/l, the adsorption is dependent on the specific surface area. If the initial concentration of phenol is low as $100{\mu}g/l$, the adsorption is dependent on the average pore volume. The acidic surface functional groups prevent the adsorption of phenol molecules to activated carbon. And the adsorbed amount decreases more for $HNO_3$ treatment than for $H_2O_2$ treatment and more for concentrated $HNO_3$ treatment than for dilute $HNO_3$ treatment.

• Journal of Korean Society of Water and Wastewater
• /
• v.21 no.2
• /
• pp.151-164
• /
• 2007

Criteria for rehabilitation priority are discussed to evaluate structural stability of deteriorated water transport and transmission pipes, in this study. For the purposes, safety factor is introduced and estimated by measuring tensile strength and by analyzing stress caused by the internal-external loads working on buried pipe body. Related informations are surveyed and collected under various conditions in the fields by digging out and the structural stability is assessed. In the evaluation results of structural safety, it is shown that steel pipe is more affected by external load than internal load. The average external load is estimated as $53.7kg/cm^2$ and total hoop stress is estimated by $2676.5kg/cm^2$. Also, Poisson effect into longitudinal direction due to internal and external loads is most influential on hoop stress. The calculated safety factors of hoop stress are ranged from 0.7 to 5.2 with average value of 2.1, considering a bending stress to longitudinal direction. The decision of rehabilitation priority by safety factors show that structural safety of CIP sample 1(S1) was assessed at the lowest order with safety factor value, 0.7 and that of DI sample 15(S15) was evaluated as the most stable in structural aspect.

• Journal of Korean Society of Water and Wastewater
• /
• v.26 no.1
• /
• pp.123-129
• /
• 2012

A septic tank is a purification treatment system where night soil and other waste matter is converted into harmless material by the activities of bacteria. Effluent from the septic tank flows into the sewer pipe, and then this effluent affects the quality of water environment and makes foul smell. In this study, through the proper maintenance of septic tank it was tried to minimize the impact of sewer pipe on water quality and fouling smell. BOD removal rate from the septic tank's effluent which exceeded legal cleaning period was investigated for the proper maintenance. BOD Removal rate of the twelve septic tank's effluent is -62.5% to 43.9%. According to the result of BOD removal rate, septic tank cleaning should be done at least once a year. And the pathogenic coliform bacillus in the twelve septic tank's effluent is average 768,000 (MPN/$100m{\ell}$). The chlorine disinfection is needed to remove the pathogenic coliform bacillus in septic tank effluent.

• Journal of environmental and Sanitary engineering
• /
• v.7 no.1
• /
• pp.1-16
• /
• 1992

Corrosion of pipes Is one of the most serious problems in the maintenance of water worlds. Corrosion is promoted not only by physical factors such as temperature, but also by electrochemical factors including concentration of soluble metal ions, chlorine ion, pH, DO and microorganisms. Corrosion products also affect corrosion rate. In this research, study results are summarized as follows ; 1) Corrosion test was performed for 4 weeks at $70^{\circ}C$, pH 7.0 with specimens of 4 types of metal materials used as service pipes. Corrosion rate and S.E.M were analyzed. The results were showed that corrosion 1.ate of carbon steel pipe was 4.10~5.22 $mg/\textrm{cm}^2$ . week, galvanized steel pipe 0.98~1.34$mg/\textrm{cm}^2$. week, Copper pipe 0.02~0.04$mg/\textrm{cm}^2$. week, stainless steel pipe 0.05~ 0.10$mg/\textrm{cm}^2$ . week. 2) When corrosion rate was tested for tile types of pipes at pH 7 and both $25^{\circ}C$ and $75^{\circ}C$, avaerage corrosion rate for 6 weeks at $25^{\circ}C$ Ivas 2.26$mg/\textrm{cm}^2$ . week in carbon steel pipe, 1.99$mg/\textrm{cm}^2$. week in galvanized steel pipe, 0.26 $mg/\textrm{cm}^2$. week in stainless steel pipe. At $87^{\circ}C$, average corrosion rate for 4 weeks u.3s 4.56 $mg/\textrm{cm}^2$. week in carbon steel pipe,