• The Journal of Engineering Geology
• /
• v.16 no.3 s.49
• /
• pp.255-263
• /
• 2006

In an electrical tomographic survey using an inclined borehole with a pole-dipole array, we must consider several factors: a singular point associated with zero potential difference, a spatial discrepancy between electrode and nodal point in a model due to a inclined borehole, and a variation of geometric factors in connection with a irregular topography. Singular points which are represented by the normal distance from current source to the ground surface can be represented by serveral regions due to a irregular topography of ground surface. The method of element division can be applied to the region in which the borehole is curved, inclined or the distance between the electrodes is shorter than that of nodal points, because the coordinate of each electrode cannot be assigned directly to the nodal point if several electrodes are in an element. Test on a three-dimensional (3-D) synthetic model produces good images of conductive target and shoves stable convergence.

• Korean Journal of Weed Science
• /
• v.17 no.4
• /
• pp.407-412
• /
• 1997

Allelopathic activity of methanol extract from medicinal plants was determined based on the inhibition of germination, shoot and root length of Echinochloa crus-galli. The response was depended on the source of extracts and concentrations. Of the 20 test plants tested, Cnidium officinale showed most inhibition according to germination, shoot and root length of E. crus-galli. Based on the plant parts, the root extract of C. officinale had more inhibitory effect on E. crus-galli than the stem+leaf extract. Phytotoxic effects of the root extract on E. crus-galli showed 75% inhibition of seed germination, 95% inhibition of shoot growth, and 100% inhibition of root growth at the concentration of 1g/petridish. Sequential partitioning of root extract with organic solvents with increasing polarity showed that the ethylacetate fraction had the greatest inhibitory effect on E. crus-galli. Germination was not inhibited at any rate of ethylacetate fraction but shoot and root growth, were significantly inhibited even at 2mg/petridish. This indicates that the most toxic phytotoxin present in the root extract may be moderate polar compound.

• Journal of the Korean Society of Food Science and Nutrition
• /
• v.25 no.5
• /
• pp.741-746
• /
• 1996

Antibacterial activities of the bamboo(Pseudosasa japonin Makino) leaves extract on lactic acid bacteria related to Dongchimi fermentation were investigated. The bamboo leaves were extracted with 70% ethanol, fractionated it with 4 solvents which have a different polarity. Total viable count was very similar to those obtained by lactic acid bacteria during fermentation of Dongchimi. Its maximum counts were (equation omitted) 10$^{7}$ CFU/m1 at 8 days of fermention. Lactic acid bacteria isolated during Dongchimi fermentation were identified as Leuconostoc species(BK-2, BK-07, BK-22), Lactobaillus species (BK-05, BK-08) and Streptococcus species(BK-15) 70% ethanol extract of the bamboo leaves showed antibacterial activity against strain BK-02, BK-07, BK-lS and BK-22. Especially, strain BK-22 was more effective to the extracted substance. Among the each fractions, 70% ethanol and diethyl ether had the strongest antibacterial activity against strain BK-22 and BK-07, respectively. The two fractions also showed similar activities against all of the test strains.

• Resources Recycling
• /
• v.18 no.1
• /
• pp.13-21
• /
• 2009

A research on material separation of EVA and PET mixture plastic waste using a triboelectrostatic separator has been carried out. It was found that PP was the best charging material to give the highest charge on the surface of EVA and PET mixture plastics with an opposite polarity. Therefore, a charger of pipe line type using PP material was manufactured for separation of EVA and PET mixture plastic waste. At optimum test conditions that used PP cyclone charger developed in this study, we could separate out PET with a glade of 98.7% and a recovery of 89.7%.

• Resources Recycling
• /
• v.17 no.1
• /
• pp.43-50
• /
• 2008

In this study, we carried out the research on triboelectrostatic separation for materials separation of PET & Nylon recovered to waste plastic beer bottle. From the research on charging characteristic for choice of charging materials, it was found that PMMA was optimum charging material to make high charging amount with opposite polarity for PET & Nylon in waste plastic beer bottle. Therefore, we manufactured a charger of pipe line and cyclone type using PMMA material for separation of PET and Nylon. At optimum test conditions that used PMMA pipe line and cyclone charger developed in this study, we developed a triboelectrostatic separation technique that can separate PET plastic up to grade of 99.6% and recovery of 88.2%. We established new separation technology that can recycle the PET and Nylon recovered from waste plastic beer bottle.

• Korean Journal of Environmental Agriculture
• /
• v.11 no.2
• /
• pp.146-154
• /
• 1992

DDVP, malathion and diazinon ECs which differ in chemical compositions and moisture contents were formulated with nine emulsifiers, three solvents(xylene, cyclohexanone and DMF) and epichlorohydrin. For the studies of decomposition characteristics, these technicals and ECs were subjected to the test under elevated temperature at $54^{\circ}C$ for 15 days and $38^{\circ}C$ for 90 days respectively. DDVP technical was rapidly decomposed in early stage of thermoaccelerated test at $54^{\circ}C$, but the decomposition rate slowed down with time. As for malathion and diazinon technicals, the longer they were incubated, the more decomposed. The decomposed AI in ECs increased with solvent polarity. The increment of moisture content in ECs accelerated the decomposition of AI, and that was remarkable especially in diazinon ECs. Addition of emulsifiers increased the moisture content to be accelerated the decomposition of AI, but the decomposition of AI was more affected by the kind of emulsifier than by the moisture content of emulsifier, Stabilizing effect by epichlorohydrin was distingished in malathion and diazinon ECs, but there was no effect in other solvent-based formulation except xylene.

• Journal of Intelligence and Information Systems
• /
• v.22 no.3
• /
• pp.71-89
• /
• 2016

Sentiment analysis is used for identifying emotions or sentiments embedded in the user generated data such as customer reviews from blogs, social network services, and so on. Various research fields such as computer science and business management can take advantage of this feature to analyze customer-generated opinions. In previous studies, the star rating of a review is regarded as the same as sentiment embedded in the text. However, it does not always correspond to the sentiment polarity. Due to this supposition, previous studies have some limitations in their accuracy. To solve this issue, the present study uses a supervised sentiment classification model to measure a more accurate sentiment polarity. This study aims to propose an advanced sentiment classifier and to discover the correlation between movie reviews and box-office success. The advanced sentiment classifier is based on two supervised machine learning techniques, the Support Vector Machines (SVM) and Feedforward Neural Network (FNN). The sentiment scores of the movie reviews are measured by the sentiment classifier and are analyzed by statistical correlations between movie reviews and box-office success. Movie reviews are collected along with a star-rate. The dataset used in this study consists of 1,258,538 reviews from 175 films gathered from Naver Movie website (movie.naver.com). The results show that the proposed sentiment classifier outperforms Naive Bayes (NB) classifier as its accuracy is about 6% higher than NB. Furthermore, the results indicate that there are positive correlations between the star-rate and the number of audiences, which can be regarded as the box-office success of a movie. The study also shows that there is the mild, positive correlation between the sentiment scores estimated by the classifier and the number of audiences. To verify the applicability of the sentiment scores, an independent sample t-test was conducted. For this, the movies were divided into two groups using the average of sentiment scores. The two groups are significantly different in terms of the star-rated scores.

• Particle and aerosol research
• /
• v.14 no.4
• /
• pp.153-169
• /
• 2018

To identify a variety of organic compounds in the ambient aerosols, the two-dimensional gas chromatography-time of flight mass spectrometry (GCxGC) system (2DGC) has been applied. While 2DGC provides more peaks, the amount of the generated data becomes huge. A two-step approach has been proposed to efficiently interpret the organic aerosol analysis data. The two-dimensional 2DGC data were divided into 6 chemical groups depending on their volatility and polarity. Using these classification standards, all the peaks were subject to both qualitative and quantitative analyses and then classified into 8 classes. The aerosol samples collected in Seoul in summer 2013 and winter 2014 were used as the test case. It was found that some chemical classes such as furanone showed seasonal variation in the high polarity-volatile organic compounds (HP-VOC) group. Also, for some chemical classes, qualitative and quantitative analyses showed different trends. Limitations of the proposed method are discussed.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
• /
• v.21 no.1
• /
• pp.52-59
• /
• 2007

A field mill capable of measuring the magnitude and polarity of electric fields at the ground level was studied to apply to a lightning warning system as a sensor. We designed and fabricated a planar-shutter type field mill with a rotating-vanes. A calibration of the field mill was performed in a vertically symmetrical arrangement which consists of two equal size parallel round plates to form a homogeneous electrical fields. The sensitivity of the field mill was adjusted at 0.5[V/kV/m], and this covers a ranges from 200[V/m] to 20[kV/m]. After the calibration experiment, the field mill was installed on the roof of a building to measure the changes of electric field intensity caused by thunderclouds. During the period from July 1. 2006 to July 15. 2006, the electric field intensity was recorded a ranges of $+2[kV/m]{\sim}-6[kV/m]$ depending on generation, extinction and movement of thunderclouds. From the actual test on the ground it is confirmed that the field mill has a good performance necessary for the measurement of DC electric fields.

• Journal of the Korean Chemical Society
• /
• v.54 no.6
• /
• pp.809-817
• /
• 2010

The primary purpose of this study was to investigate high school students' conceptual understanding of density for solids and liquids in pure and mixed substances who had preceded formal school science instruction on density and related topics. A concept assessment on density was developed and administered by demonstrative experiments accompanied by a written assessment test method to 120 general high school students in a metropolitan city. The scientific conceptions and alternative conceptions from students' responses were identified and the percentages of them were calculated. Then, their alternative conceptions and implicit theories on density were analyzed. About half of the students couldn't differentiate weight-volume-density and regarded density as an innate property of matter. Furthermore, the greater the number of variables involved in an experimental condition of the question, the more complicated and undifferentiated students' density concepts were. Students employed more improper variables such as particle size, intermolecular distance, surface tension, polarity of the solvent, etc. in explaining counter-intuitive observations. The implications for school science instruction were discussed.