본 실험은 장미 식물생산공장식 수경재배시 배양액의 EC와 pH와 같은 지하부 환경요인이 장미의 생육과 품질에 미치는 영향을 알아보고자 수행하였다. 배양액의 EC를 1.0~3.5dS·m-1로 처리하였을 때 장미의 생육과 품질에 미치는 영향은 큰 차이가 없어 비료의 사용량을 고려하여 배양액의 농도를 높게 관리할 필요가 없는 것으로 나타났다. 광합성률, 증산률 및 생육 등은 EC 1.0~1.5dS·m-1에서 높아 single-stemmed rose수경재배에 있어 최적의 농도임을 알 수 있었다. 배양액의 pH는 pH 3.0과 7.0을 제외한 pH 4.0~6.0에서 광합성률과 증산률이 높게 나타나 장미는 배양액의 pH를 다른 작물에 비해 낮게 관리하는 것이 생육이나 무기이온 흡수에 있어 효과적인 것으로 나타났다.

The sales activity of most of small manufacturing companies is based on orders of buyers. The process of promotion, receipt and selection of orders of the manufacturers is closely coupled with the load status of the production lines. The decision on wheth

This paper presents the interrelationship chart between software quality characteristics and engineering attributes. The software quality characteristics and their subcharacteristics are excerpted front IS0/1EC 9126 standards, and the engineering attributes are from Deutsch and Willis[4]. Based on the previous studies and subjective judgement, trisected interrelationship(strong, medium, weak) between these two groups are derived. The results are summarized in a table, and can be used as a quick reference guide to the software quality engineering applications such as quality evaluations for software products, selection of key engineering attributes for high-quality software production, and so forth.

독소원성 대장균(EC81, O148:H28)이 생산하는 이열성 장독소와 독소원성 C. perfringens A형(NCTC8238, Hobbs serotype 2)이 생산하는 장독소에 대하여 PCR기법의 감도를 검색한 결과, 독소원성 대장균은 100 ng/ul로부터 1pg 희석용액에서까지 417-bp의 LT DNA fragment가 확인되었으며 독소원성 C. perfringens A형은 100 ng/ul로부터 10 pg 희석용액에서까지 364-bp의 장독소 DNA fragment가 확인되어, 독소원성 대장균이 독소원성 C. perfringens A형보다 10배의 높은 감도를 나타내었다.

Internet상의 전자문서, 전자거래 등과 관련된 전자업무에서는 다음과 같은 중요 인증 문제를 필요로 하게 한다. 첫째, 당사자(사용자)의 신분확인 기능(신원확인). 둘째, 전자업무 내용의 정보보호 및 무결성 기능(비밀성 보장). 셋째, 전자행위에 대한 부인봉쇄(분쟁해결) 등이 그것이다. 따라서 이러한 전자업무의 중요 인증 문제와 관련하여 신뢰할 만한 제3자, 즉 인증기관(CA : Certificate Authority)의 확인 및 증명해주는 제도가 필요하다. 위에서 언급한 제 가지 인증 문제 중 전자업무에서의 가장 기초적인 인증 문제인 당사자(사용자)의 신분확인 기능(신원확인)에 대한 문제를 연구하고자 한다.

본 실험은 상추 수경재배시 지하부 환경요인이 상추의 생육에 미치는 영향을 바탕으로 식물공장에서 활용가능성이 큰 상추의 최적 근권환경을 알아보고자 수행하였다 근권부 환경조건으로는 배양액의 pH와 U를 각각 여러 가지 수준으로 실험하였다. pH 3.0을 제외한 pH 4.0~8.0에서 가시적인 생리장해 없이 양호한 생육을 나타냈으나 광합성, 증산량 및 무기이곤 흡수를 고려한 상추의 최적 배양액 pH는 pH 5.5~6.0였다. 배양액의 전기전도도는 0.8~3.6 mS.cm-1 /로 처리하였을 때, 고농도에서는 Ca결핍으로 인한 잎끝마름증이 나타나 품질이 저하되었고 생육과 광합성이 높은 EC 1.2~l.6mS.cm-1 /가 최적인 것으로 나타났다. 이런 결과는 상추 식물공장에서 상추의 주년생산, 공장적 대량생산 및 청정생산 등의 효율적인 재배를 하는데 기여 할 수 있을 것으로 보인다.

국내 원예시설의 증가와 더불어 양액재배농가도 증가추세에 있어 저렴한 국산 양액재배 자동화기기가 농가에 필요한 실정이다. 이에 따른 양액재배의 EC와 pH를 자동조절하기 위하여 마이크로컴퓨터의 일종인 PLC(programmable logic controller)를 이용한 장치를 개발하고 재배실험을 실시한 결과를 요약하면 다음과 같다. 1. Ladder diagram언어를 사용하여 양액재배의 자동화 프로그램을 작성하였다. 2. PLC를 이용하여 양액의 EC, pH수준을 1.70-l.72mS/cm, 6.1-6.5로 전 생육기간 동안 유지시킬 수 있었다. 3. 대조구에 비하여 처리구가 상품과(당도 5.0 oBrix, 산도 0.4% 이상) 및 수량성이 높은 결과를 얻었다. 4. 식물체의 무기성분 함량은 처리구가 대조구에 비해 전체적으로 높았다.

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).

Electrical Conductivity (EC) or Total Dissolved Solids (TDS) has been often used to evaluate the water quality in some water education program for children and youth. This study attempted to find out whether EC (or TDS) can be used as a water pollution criteria in water education program. To clarify it, we used the water analysis data of July 2019 and January 2020 from Water Environment Information System. Data from 332 points in Han-river were used to investigate correlation between the parameters, such as BOD, COD, TN, TP vs EC. Correlation(r) for all data of BOD vs. EC was 0.347 for July 2019 and 0.483 for January 2020. No correlation was observed for BOD Ia and BOD Ib for July 2019 (r=-0.041, -0.030, respectively) and BOD Ia for January 2020 (r=0.041). Better correlation for all data of COD vs. EC was obtained (r=0.543 for July 2019 and r=0.610 for January 2020). However, no correlation was observed for COD Ia for January 2020. High vlaue of EC or TDS does not always mean water pollution, especially for clean water environment. Thus, EC (or TDS) alone can not be used as a water pollution criteria.

Supply electrical conductivity (EC) concentration of the nutrition solution is an important factor in the absorption of nutrients by plants and the management of the root zone, as it can control the vegetative/reproductive growth of a plant. Paprika usually undergoes its reproductive and vegetative growth simultaneously. Therefore, ensuring proper growth of the plant leads to increased yield of paprika. In this study, growth characteristics of paprika were examined according to the EC concentration of a coir and a rockwool substrate. The supply EC was 1.0, 2.0, and 4.0 mS·cm-1 applied at the initial stages of the growth using the rockwool (commonly used by paprika farmers) and the coir substrate with a chip and dust ratio of 50:50 and 70:30. For up to 16 weeks of paprika growth, EC concentrations of 1.0 and 2.0 mS·cm-1 were found to have a greater effect on the growth than EC at 4.0 mSꞏcm-1. The normality (marketable) rate of fruit, the soluble solid content, and paprika growth showed that the coir was generally better than the rockwool regardless of the supply EC concentration. The values of the yield per plant at an EC concentration of 4.0 mS·cm-1 was mostly similar at 1.6 kg (coir 50:50), 1.5 kg (coir 70:30) and 1.5 kg (rockwool), but the yield of the rockwool was 88%, which was lower than 98% and 94% yield of the coir substrate. Therefore, this concludes that coir substrate is more effective than rockwool at improving paprika productivity. The results also suggest that the use of coir substrate for paprika has many benefits in terms of reducing production costs and preventing environmental destruction during post-processing.

Exposure to Diesel Particulate Matter (DPM) potentially causes adverse health effects (e.g. respiratory symptoms, lung cancer). Due to a lack of data on Elemental Carbon (EC) exposure levels in underground copper ore mining (unlike other underground mining industries such as non-metallic and coal mining), this case study aims to provide individual miners’ EC exposure levels, and information on their work practices including use of personal protective equipment. EC measurement was carried out during different work activities (i.e. drilling, driving a loader, plant fitting, plant operation, driving a Specialized Mining Vehicle (SMV)) as per NIOSH Method 5040. The copper miners were working 10 h/day and 5 days/week. This study found that the most significant exposures to EC were reported from driving a loader (range 0.02-0.42 mg/m3). Even though there were control systems (i.e. water tanks and DPM filters) on the diesel vehicles, around 49.5% of the results were over the adjusted recommendable exposure limit (0.078 mg/m3). This was probably due to: (1) driver’s frequently getting in and out of the diesel vehicles and opening the windows of the diesel vehicles, and (2) inappropriate maintenance of the diesel vehicles and the DPM control systems. The use of the P2 type respirator provided was less than 19.2%. However, there was no significant difference between the day shift results and the night shift results. In order to prevent or minimize exposure to EC in the copper ore mine, it is recommended that the miners are educated in the need to wear the appropriate respirator provided during their work shifts, and to maintain the diesel engine and emission control systems on a regular basis. Consideration should be given to a specific examination of the diesel vehicles’ air-conditioning filters and the air ventilation system to control excessive airborne contaminants in the underground copper mine.