SiO2를 첨가한 Cr2O3의 전기전도도와 미세구조를 산소분압, 온도, 그리고 SiO2첨가량에 따라 측정하였다. 입자직경은 1μm보다 작다. 순수한 Cr2O3의 전기전도도는 산소분압과 온도가 증가함에 따라 증가하였으며 1100˚C부터 진성 영역이 나타났다. Cr2O3의 전기전도도는 SiO2첨가로 감소하지만, 산소분압에 따른 변화는 SiO2첨가와 무관하다.

As the automation of nutrient solution management proceeds in the field of hydroponics, effective supporting systems to manage the nutrient solution by computer become needed. This study was attempt to predict the EC of nutrient solution using the neural networks. The multilayer perceptron consisting of 3 layers with the back propagation learning algorithm was selected for EC prediction, of which nine variables in the input layer were the concentrations of each ion and one variable in the output layer the EC of nutrient solution. The meq unit in ion concentration was selected fir input variable in the input layer. After the 10,000 learning sweeps with 108 sample data, the comparison of predicted and measured ECs for 72 test data showed good agreements with the correlation coefficient of 0.998. In addition, the predicted ECs by neural network showed relatively equal or closer to the measured ones than those by current complicated models.

The optimum management of nutrient solution needs the effective combination of fertilizers as well as the accurate control of nutrient solution. This study was attempt to make a supporting system for effective fertilizer combination by using computer and also to develop a EC predicting equation for keeping the EC of solution within the allowable range after application of combined fertilizers. The supporting system consists of three parts : (1) data bases, (2) rules for deciding the kinds and amounts of fertilizers and (3) main control. With input data, the main control automatically constructs the network connecting the related data bases and subsequently executes the operation of searching proper fertilizers through it. For more effective searching, fertilizers are classified into two levels(level 1 and level 2) in consideration of solubility, price, and frequency in use, and searched in that order. The EC prediction equation, a extended form of the Robinson and Stroke's theoretical equation only available for a binary electrolyte, is suggested for predicting the EC of the nutrient solution containing many kinds of inorganic compounds. The comparison of predicted and measured ECs showed good agreements with the high correlation between the predicted EC decrement by ion interaction and the actual one(limiting EC minus measured EC).

Solar electrical conductivity has been calculated, making use of Yun and Wyller's formulation. The computed results arc presented in a tabulated form as functions of temperature and pressure for given magnetic field strengths. The results of the calculation show that the magnetic field does not play any important role in characterizing the electrical conductivity of the ionized gas when the gas pressure is relatively high (e.g., P ≥ 10 4 d y n e s / c m 2 ). However, when the gas pressure is low (e.g., P ≤ 10 d y n e s / c m 2 ), the magnetic field becomes very effective even if its field strength is quite small (e.g., B ≤ 0.01 gauss). It is also found that, except for lower temperature region (e.g., T ≤ 10 4 ∘ K ), there is a certain linear relationship in a log- log graph between the pressure and the critical magnetic field strength, which is defined as a field strength capable of reducing the non-magnetic component of the electrical conductivity by 20%.

Moving average precipitation provides periodic precipitation patterns by solving precipitation irregularities. However, due to uncertain moving average periods, excessive data smoothing occurs, which limit the possibility to analyze groundwater levels in the short term. Nonetheless, groundwater level fluctuation can compensate these limitations as it can calculate appropriately for unit time and verify the effect of precipitation penetrated into groundwater in a short time period. In this study, the characteristics of groundwater level were evaluated using groundwater level fluctuation to compensate for limitations of groundwater level analysis using moving average precipitation. In addition, the groundwater quality was investigated using the electrical conductivity fluctuation. The study site was Hyogyo-ri, Yesan-si, Chungcheongnam-do. Four observation wells and an automated weather system were used. The correlation between groundwater level fluctuation and precipitation (Case 1) and the correlation between groundwater level and moving average precipitation (Case 3) were compared. In the analysis for 1 hour data, the correlation coefficient of Case 1 was higher than that of Case 3, and in the analysis for 1 day data, the correlation coefficient of Case 3 was higher than that of Case 1.

탄산화가 고전도성 시멘트 복합재료의 전기전도도에 미치는 영향에 대해 실험적으로 확인 하였다. 탄소나노튜브(carbon nanotube, CNT)가 혼입된 페이스트형 및 모르타르형 시멘트 복합재료를 설계하였으며, 제조된 시편을 촉진탄산화 환경에 노출 시켰다. 반년간의 노출 후 확인한 결과 시멘트 복합재료의 전기전도도가 급격하게 감소한 것을 확인 할 수 있었다. 이 특성은, 전도성 시멘트 복합재료를 콘크리트용 센서로 사용했을 때, 탄산화에 의해 복합재료의 전기전도도가 변화할 수 있음을 고려해야 한다는 증거임과 동시에, 이 복합재료가 탄산화 센서로 사용될 수도 있다는 것을 의미한다. 본 논문은 본 연구 진의 기존논문 Lee et al.(2019)를 요약한 것이다.

전기전도도가 높은 시멘트 복합재료에 염소가 침투했을 경우 그 자체의 전기전도도가 어떻게 바꾸었는지를 실험적으로 확인 하였다. 시멘트 복합재료의 전기전도도 확보를 위해 탄소나노튜브(carbon nanotube, CNT) 및 탄소섬유(Carbon fiber)를 사용하였다. 염소의 침투가 시멘트 복합재료에 미치는 영향을 알아보기 위해 1) 염화나트륨을 배합 시 적당량 혼입하는 방법과 2) 염화나트륨 수용액에 전도성 시멘트 복합재료를 함침시키는 두가지 방법을 활용하였다. 실험 결과 염소 침투에 의해 전기전도도가 일부 증가하는 경우와 함께 반대로 감소하는 경우도 동시에 발견되었다. 본 논문은 본 연구진의 기존 논문 Lee et al.(2019)을 요약한 것이다.

이 연구는 고성능 섬유보강 복합체(HPFRCC)의 전자파 차폐성능을 향상시키기 위한 목적으로 전기전도도, 전자파 차폐능, 역학적 강도를 조사하였다. 강섬유, 제강슬래그 미분말, 카본블랙이 전도성재료소 HPFRCC 배합에 첨가되었다. 또한, MWCNT를 수 분산 시켜 제조된 2% wt. CNT 용액을 사용하였다. 실험 결과, HPFRCC의 전기전도도는 1% 카본블랙이 첨가된 시편을 제외하고는 매우 낮은 특성을 보였다. 시멘트 매트릭스의 미세구조는 시간에 따라 변하였고, 그로 인해 HPFRCC의 전기전도성 네트워크에 부정적인 영향을 끼쳤다. 0.083 S/cm의 전도도를 갖는 HC1 시편의 경우, 수분에 의한 효과를 배제하기 위하여 72시간 60도에서 건조 양생한 후에 측정한 전기전도도가 0.0003 S/cm로 상당히 감소하였다. 전자파 차폐 성능에 가장 중요한 인자는 강섬유인 것으로 나타났으며, 반면 카본블랙과 제강슬래그 미분말의 효과는 미미하였다. 전기전도도와 전자파 차폐능의 상관관계는 이 연구에서는 뚜렸한 경향성을 나타내지는 않았다.

Background : This study examined EC in soil depending on leaking water rate of sun shading facilities and conducted experiments to establish the proper leaking water rate for ginseng depending on rainfall. Methods and Results : For leakage examination, rainfall flowing into a ridge. As sun shading facilities of ginseng to examine leakage, four kinds such as Blue-Pe-sheet, Pe4 (four–layered polyethylene net) + Pe2 (two–layered polyethylene net), Pe4, Pe2 were installed. As for leakage, a plastic box (23 × 30 × 30 ㎝) was installed on the ridge of ginseng field and outside, rainfall into the box during precipitation was examined, and the leakage quantity was calculated as the ratio of the quantity into the ginseng field regarding rainfall outside. The leakage quantity was examined a total of six times on July 2, July 3, August 24, August 30, August 31, and September 4. Regarding EC in soil, WT–1000n (www.rfsenser.co) which is a EC measuring instrument was used, and the average was calculated through 3 repeated examinations. There are little differences in the leakage quantity depending on the sun shading with 0.1% of the Blue-Pe-sheet, 2.3% of Pe4 + Pe2, 4.3% of Pe4, and 30.7% of Pe2. At the leakage rate of 0.1%, EC decreased from 1.52 ds/m on July 3 to 1.04 ds/m on August 8, and increased again to 1.54 ds/m on September 3 At the leakage rate of 2.4%, EC changes were lower than that of the leakage quantity of 0.1%, and similar results depending on periods were found. At the leakage rate of 4.3%, salt concentration was measured at 0.92 ds/m on July 3, decreased since then, increased to 0.90 ds/m on September 3, and overall concentration was less than 1.0 ds/m. At the leakage rate of 30.7%, EC was the lowest at 0.46 ds/m and similar results were found since then. Conclusion : The differences in leakage quantity depending on sun shading facilities of ginsengs affected EC in soil, and EC became lower with more leakage quantity. As for the leakage quantity to maintain the EC in soil proper for ginseng growth and development lower than 1.0 ds/m, it was found to be effective to control the leakage quantity at 30% in May - June, and September - October when there are less rainfall, and at 2 - 5% in July - August when there are heavy rainfall.

Background : Ginseng sometimes develops physiological disorders as EC of soil accumulates in sun shading facilities with no leaking water. In addition, it is difficult to make moisture content of soil and EC stably suitable for ginseng growth and development in the same sun shading facility. Accordingly, this study examined EC in soil depending on leaking water rate of sun shading facilities and conducted experiments to establish the proper leaking water rate for ginseng depending on rainfall. Methods and Results : For leakage examination, rainfall flowing into a ridge. As sun shading facilities of ginseng to examine leakage, four kinds such as Blue-Pe-sheet, Pe4 (four–layered polyethylene net) + Pe2 (two–layered polyethylene net), Pe4 , Pe2 were installed. As for leakage, a plastic box (23 × 30 × 30 ㎝) was installed on the ridge of ginseng field and outside, rainfall into the box during precipitation was examined, and the leakage quantity was calculated as the ratio of the quantity into the ginseng field regarding rainfall outside. The leakage quantity was examined a total of six times on July 2, July 3, August 24, August 30, August 31, and September 4. Regarding EC in soil, WT-1000n which is a EC measuring instrument was used, and the average was calculated through 3 repeated examinations. There are little differences in the leakage quantity depending on the sun shading with 0.1% of the Blue-Pe-sheet, 2.3% of Pe4 + Pe2, 4.3% of Pe4, and 30.7% of Pe2. At the leakage rate of 0.1%, EC decreased from 1.52 ds/m on July 3 to 1.04 ds/m on August 8, and increased again to 1.54 ds/m on September 3 At the leakage rate of 2.4%, EC changes were lower than that of the leakage quantity of 0.1%, and similar results depending on periods were found. At the leakage rate of 4.3%, salt concentration was measured at 0.92 ds/m on July 3, decreased since then, increased to 0.90 ds/m on September 3, and overall concentration was less than 1.0 ds/m. At the leakage rate of 30.7%, EC was the lowest at 0.46 ds/m and similar results were found since then. Conclusion : Differences in leakage quantity depending on sun shading facilities of ginseng affected EC in soil, and EC became lower with more leakage quantity. For the leakage quantity to maintain the EC in soil proper for ginseng growth and development lower than 1.0 ds/m, it was found to be effective to control the leakage quantity at 30% in May - June, and September - October when there are less rainfall, and at 2 - 5% in July - August when there are heavy rainfall.

In this study, it evaluate the electrical conductivity of fiber reinforced cement composite by Fiber type. Hooked-ended steel fiber, Smooth steel fiber and Amorphous metallic fiber were reinforced 2.0 vol.% in cement composites respectively. The electrical conductivity was evaluated by calculating the electrical resistivity of each specimen after measuring the electrical resistance.

본 연구에서는 TDR의 반향파의 특성과 총토양전기전도도의 관계를 이용한 비포화 토양에서의 용존오염원 농도를 측정하는 방법을 개발하였다. 본 연구에서 제안한 방법은 두 가지 중요한 관계를 결합한 것으로 첫 번째는 함수량이 일정할 경우 전기전도도와 토양수 농도는 선형관계를 유지한다는 것이며, 두 번째는 천이상태의 용존여염원의 농도를 측정할 수 있게 하기 위해 함수량과 전기전도도의 관계를 설정하는 것이다. 함수량과 전기전도도의 관계를 추정하는 식들이 여러 연

종자가 수분을 흡수할 때 특히 퇴화종자에서 종자의 내용물질을 밖으로 누출하는데 Brassica속의 종자는 총광물질인 sinapine이 누출되는 것을 이용하여 퇴화종자를 선별하는 기술이 개발되어 있다. 따라서 본 시험에서는 무, 배추, broccoli, 참깨, 양파, 당근종자에서 sinapine이외에 전기전도도, 무기성분(K, Ca, Mg, Na), 전당, 아미노산 등의 성분들이 퇴화종자와 건전종자 사이에 어떠한 차이로 누출되는지를 검토하여 이들 성분을 이용할 때 퇴화종자를 검정할 수 있는 지표로 사용될 수 있는지를 검토하였다. 1. 종자침청호액의 전기전도도는 퇴화종자에서 시간이 경과할수록 높아졌는데 십자화과 종자인 무, 배추, broccoli종자에서 뚜렷한 차이가 있었으나 양파와 당근종자에서는 전기전도도도 낮았고 차이도 거의 없었다. 2. 무기물의 누출에서는 무기성분중 potassium이 가장 많이 누출되었으며 퇴화종자와 건전종자 사이의 차이도 컸지만 기타 Ca, Mg, Na에서는 누출양도 적었고 차이도 적었다. 또 십자화과 종자에서는 누출이 많았고 양파와 당근종자에서는 누출이 적었다. 3. 전당의 누출도 퇴화종자에서 건전종자보다 높았으며 역시 십자화과 종자에서 누출양과 차리가 컸으나 양파, 당근종자에서는 누출양과 차이가 적었다. 4. 아미노산의 누출도 퇴화종자와 건전종자사이에 차이가 컸으나 품종간 차이가 다양하였고 십자화과 종자에서 누출양이 많았으나 양파나 당근종자에서는 누출양이나 차이가 적었다. 5. 전당과 아미노산은 종자침청 후 약 4시간에서부터 건전종자와 퇴화종자에서 누출양의 차이를 보였다.