• Journal of the Korean Medical Association
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• v.61 no.12
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• pp.749-755
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• 2018

Particulate matter is an air pollutant emitted from both natural and anthropogenic sources, and its adverse health effects have been well documented in time-series analyses and cohort studies. The effect size of particulate matter exposure-a roughly 0.5% increase in mortality for each $10{\mu}g/m^3$ increment of short-term exposure to particulate matter with aerodynamic diameter ${\leq}10{\mu}m$ and approximately a 10% increase for each $10{\mu}g/m^3$ increment of long-term exposure to particulate matter with aerodynamic diameter ${\leq}2.5{\mu}m$-is small compared to other risk factors, but the exposure is involuntary and affects the entire population, which makes particulate matter pollution an important public health issue. The World Health Organization and Korean government have both established guidelines for particulate matter concentrations, but the Korean guideline is less stringent than that of the World Health Organization. The annual mean concentration of particulate matter in Korea is decreasing, but the trend seems to be slowing. In addition to policy efforts to reduce particulate matter emission, personal approaches such as the use of face masks and air purifiers have been recommended. Personal approaches may not solve the fundamental problem, but can provide temporary mitigation until efforts to reduce emission make progress.

• Journal of Plant Biology
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• v.14 no.1
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• pp.5-13
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• 1971

Accumulation of soil organic matter and its vertical distribution at different latitudes in peninsular Korea were studied in the soil of four different forest types viz. Pinus densiflora forest, Castanea forest, Quercus acutissima forest and Carpinus laxiflora forest. Among them, accumulation of soil organic matter in Cheju sites, with a mean annual temperature of 15$^{\circ}C$, was maximum with increasing latitude, soil organic matter concentration decreased. Considering the relationship between concentration of soil organic matter and some climatic conditiions, it seems that concentrations of soil organic matter is a function of annual temperature, especially warmth index or cold index.

• Journal of the Korean Physical Society
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• v.73 no.10
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• pp.1596-1602
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• 2018

We suggest that the dark matter in the universe has quantum entanglement if the dark matter is a Bose-Einstein condensation of ultra-light scalar particles. In this theory, any two regions of a galaxy are quantum entangled due to the quantum nature of the condensate. We calculate the entanglement entropy of a typical galactic halo, which turns out to be at least O(ln(M/m)), where M is the mass of the halo and m is the mass of a dark matter particle. The entanglement can be inferred from the rotation curves of the galaxy or the interference patterns of the dark matter density.

• Korean Journal of Organic Agriculture
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• v.4 no.2
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• pp.79-85
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• 1995

This experiment was carried out to broadcating effect of chitosan solution levels on dry matter production in Ladino clover(Trifolium repens). Chitosan solution was applie at 6 levels, 0%, 0.01%, 0.05%, 0.1%, 0.5% and 1.0%, respectively. The results obtained were summarized as follows ; 1. The dry matter yields of chitosan treatment plot were about 30%~63% more than the dry matter yield of control plot in all cuts. 2. Total dry matter yield was produced by 659.7kg/10a at levels of 0.05%, it was significantly higher than other chitosan solution levels. 3. The predictable highest yield and economic yield of Ladino clover could be obtained at 0.05% and 0.01% solution levels, respectively. 4. The relative dry matter yields for total dry matter yield were 66.7%, 18.3% and 15.0% at 1st, 2nd and 3rd cut, respectively. Chitosan application at early spring was affected to increasing the dry matter yield of 1st cut.

• Journal of Astronomy and Space Sciences
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• v.34 no.2
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• pp.153-159
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• 2017

The Standard Model of particle physics was established after discovery of the Higgs boson. However, little is known about dark matter, which has mass and constitutes approximately five times the number of standard model particles in space. The cross-section of dark matter is much smaller than that of the existing Standard Model, and the range of the predicted mass is wide, from a few eV to several PeV. Therefore, massive amounts of astronomical, accelerator, and simulation data are required to study dark matter, and efficient processing of these data is vital. Computational science, which can combine experiments, theory, and simulation, is thus necessary for dark matter research. A computational science and deep learning-based dark matter research platform is suggested for enhanced coverage and sharing of data. Such an approach can efficiently add to our existing knowledge on the mystery of dark matter.

• Korean Journal of Agricultural Science
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• v.27 no.2
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• pp.125-134
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• 2000

This observation was to investigate the influence of raw organic matter incorporated into soil at various rates on hydraulic conductivity and elution of solute throughout soil column. Generally the organic matter content in a practical agricultural field was approximately 3%. However, the application rate of organic matter in the field tends to rapidly increase in these days. Therefore, we raised the application rate of organic matter up to 10% in this investigation. From the experiment, we found that the hydraulic conductivities rapidly decreased with increasing rate of organic matter as well as rapid decrease in total volume of eluent during the same period. And electrical conductivities in the effluent significantly decreased after 2 pore volume, resulting in approaching to the criteria of saline soli. From this we could assume that the organic matter may influence the crop growth in the beginning. However excessive irrigation in the field may cause saturation of soil leading to reduction of soil. Therefore, there must be a management methods in application of organic matter with respect to soil water control.

• Journal of the Korean Chemical Society
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• v.51 no.1
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• pp.65-72
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• 2007

The purpose of this study was to examine the 7th national science curriculum (chemistry domain) regarding the meanings of ‘mulgil' (Korean), the particulate nature of matter, and the state of matter. It was found that the term of ‘mulgil' was being used vaguely as representing material, matter, or substance without clear definition. This was problematic by reason that it could hinder students from having the concept of substance. Regarding the particulate nature of matter, molecule was introduced as a basic unit of matter at grade 7, prior to atom and ion, which were introduced at grade 9 and 10, respectively. It is necessary to reconsider the sequence of each particle concept to provide students with more consistent and comprehensive understanding of structure of matter. In the case of change of state, key concepts such as conservation of matter or reversibility were omitted in the curriculum document, and explanations based on various aspects of particles were somewhat insufficient. The concept of matter is fundamental to chemistry, and we must recognize it as a concept that needs to be taught clearly. Implications for curriculum revision were discussed.

• Journal of Sensor Science and Technology
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• v.22 no.3
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• pp.191-196
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• 2013

A particulate matter sensor fabricated by MEMS process is proposed. It is developed to accommodate Euro6 on-board diagnostics regulation for diesel automobile. In the regulation, emission of diesel particulate matter is restricted to 9 mg/km. Particulate matter sensor is designed to use induced charges by charged particulate matter. To increase sensitivity of the sensor, groove is formed on sensor surface because wider surface area generates more induced charges. Sensitivity of the sensor is measured 10.6 mV/(mg/km) and the sensor shows good linearity up to 15.7 mg/km. Also its minimum detectable range is about 0.25 mg/km. It is suitable to detect failure of a diesel particulate filter which should filter particulate matter more than 9 mg/km. For removing accumulated particulate matter on the sensor which can disturb normal operation, platinum heater is designed on the backside of the sensor. The developed sensor can sense very low amount of particulate matter from exhaust gas in real-time with good linearity.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2018.10a
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• pp.623-625
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• 2018

As the issue of particulate matter spreads, services for providing particulate matter information in real time are increasing. However, when a sensor node for collecting particulate matter is defective, a corresponding service may not be provided. To solve these problems, it is necessary to predict and deduce particulate matter. In this paper, a particulate matter prediction model is designed using artificial neural network algorithm based on past particulate matter and meteorological data to predict particulate matter. Also, the prediction results are compared by learning the input data of the model in the design stage.

• Asian Journal of Turfgrass Science
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• v.7 no.2_3
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• pp.121-127
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• 1993

This experiment was carried out to compare the varietal differences of dry matter production in rend canarygrass. The varieties examined were Common, Venture, Castor, Palaton and Venture. Reed canarygrass was harvested three times annually, 1st cut(1O, May), 2nd cut(31, July), and 3rd cut(10, Oct.), respectively. The results were summarized as follows ; 1. Dry matter yield were not significant difference between varieties and for the interaction of variety$\times$cut. But, there was significant difference between cuts. 2. There was not significant difference in dry matter yield between the first cut and second cut. But, the dry matter yield of the third cut was poor than the other two cuts. Thus, the average dry matter yield of varieties were 806.1 kg, 730.8kg and 495.8kg /l0a in the first, second and third cut, respectively. 3. In Venture and Palaton, the percentage of dry matter distribution in spring was higher than that of other varieties. In Common, Castor and Vantage, they were not significantly different between the percentage of dry matter distribution in each cut. Above the results suggested that the first group of varieties(Venture and Palaton) were suited to meadow and last group of varieties(Common, Castor and Vantage) were suited to pasture. 4. Average total dry matter yield of varieties was 2,032kg /l0a/yr,(ranged from 1,922kg to 2,180 kg /l0a /yr.)