• Journal of Sensor Science and Technology
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• v.21 no.3
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• pp.223-228
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• 2012

In this study, a fiber-optic pH sensor based on a pH sol-gel film is fabricated. The sol-gel film is made by co-polymerizing tetramethoxysilane, trimethoxymethylsilane, ethanol and distilled water. As a pH indicator, a neutral red is immobilized in a thin porous film formed by the sol-gel process. The pH change in a sensing probe gives rise to a change in the color of the pH sol-gel film, and the absorbance of reflected light through the pH sol-gel film is also changed. By using a spectrometer, therefore, the spectra of reflected lights in the sensing probe with different pH values are measured. Also, the relationships between the pH values and the absorbance are analyzed on the basis of the color variations of the pH sol-gel films. In repeated experiments, the fiber-optic pH sensor shows that it has reversibility, a high reproducibility and a wide absorbance change in a pH range from pH 5 to 9. Also, we confirmed that the fabricated pH sol-gel film exhibits a fast response time, little or no pH indicator leaching and a dynamic range of 2.04 dB from pH 5 to 9. Based on the results of this study, a fiber-optic pH sensor can be developed for the pH monitoring in the harsh environments.

• KOREAN JOURNAL OF PACKAGING SCIENCE & TECHNOLOGY
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• v.28 no.3
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• pp.165-170
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• 2022

If petroleum- derived plastic like a bio-based plastic was degradation, awareness like a global warming and environmental disasters will be decreased. Plastic film was produced by adding ferric ions according to concentration by using a pro-oxidant in polyolefin resin. Changes in tensile strength, elongation, and molecular weight were evaluated according to the UV irradiation time. Increasing the amount of ferric ions resulted in more significant declines of physical properties, and also resulted in greater changes in molecular weight. After 100 hours of UV irradiation, tensile strength declined significantly in the film containing pro-oxidant as compared to the control. A similar effect was also observed in terms of elongation. The film containing pro-oxidant showed a 73.8% decrease in molecular weight after 100 hours of UV irradiation. The appropriate use of pro-oxidant can not only degrade plastic film but also control the time of degradation at the petroleum-derived plastic films. Further studies are necessary to investigate the conditions of plastic film degradation.

• Korean Journal of Plant Resources
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• v.30 no.5
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• pp.556-564
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• 2017

Appropriate soil temperature and early planting of potato is very important for the successful potato-soybean cropping system in central region of South Korea. This experiment was carried out to determine the effect of mulching materials on the growth and yield of potato (Solanum tuberosum L.). Five different mulch treatments were had been applied on an upland soil as follows ; no mulch (NM), transparent film (TF), transparent film + additional transparent film (TF + ATF), black film (BF), and black film + additional transparent film (ATF). In the period of sowing time to removing additional films, mean soil temperature of the treatments was in the order of TF+ATF > TF > BR+ATF > BF as $20.3^{\circ}C$ > $18.5^{\circ}C$ > $16.1^{\circ}C$ > $15.4^{\circ}C$, respectively and that of NM was $13.8^{\circ}C$. The accumulated soil temperature was TF > NM > BF during the removing additional films to earthing at inter-tillage. On the changes in the soil temperature during a whole day, the temperature in the BF was lower than NM during around 18:00 PM to 12:00 NM, while NM was higher than BF in the time period of 10:00AM to 21:00PM. The sequence of potato sprout emergence was 15 > 18 > 20 > 22 days of TF+ATF, TF, BF+ATF, and BF, respectively and that of NM was 24 days. Comparing to the NM, potato sprout emergence was observed on the TF+ATF treated plot as early as 9 days. At 10 days before harvest, the significant difference in the tuber dry weight had been observed and the sequence tuber weight was in the order of TF > TF+ATF > BF+ATF > BF > NM. The potato yields of TF, TF+ATF, and BF+ATF were increased of 40.7, 37.3, and 22% as compared to NM ($2,805kg\;10a^{-1}$), but almost same yield in the BF. The differences of tuber dry weight and potato yields was co-related with the temperature rise of soil by the application of mulching materials on soil. Based on these results, application of mulching film had been very effective to increase the tuber size and the yield of potato by the temperature rise during seedling stage of potato. Transparent mulching was better than black mulching especially for the emergence of sprout of potato in relation to minimizing cooling injury.

• Journal of Korean Ophthalmic Optics Society
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• v.20 no.2
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• pp.247-253
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• 2015

Purpose: The purpose of this study was to compare and analyze the ocular surface and the palpebral conjunctiva of categorized subjects, which were divided into normal eye group and dry eye group, by using a thermal camera. Methods: Subjects were 144 eyes of 72 normal university students, who didn't have any corneal disease, abnormal lacrimal ducts, medical records regarding ocular surgeries, or experience of using contact lens. Subjects were divided into two groups, which were normal eye group and dry eye group, based on the results of TBUT, Schirmer I test, and McMonnies test. After categorizing the subjects, the temperature of the subjects' ocular surface and the palpebral conjunctiva were measured and analyzed by using a thermal camera (Cox CX series, Answer co., Korea). Results: In the normal eye group's Central Ar.1, Nasal Ar.2, Temporal Ar.3, Superior Ar.4, Inferior Ar.5, the measured amount of temperature change on each area was $-0.13{\pm}0.08$, $-0.14{\pm}0.08$, $-0.12{\pm}0.08$, $-0.14{\pm}0.08$, $-0.10{\pm}0.09(^{\circ}C/sec)$. The dry eye group's results were $-0.17{\pm}0.08$, $-0.16{\pm}0.07$, $-0.16{\pm}0.08$, $-0.17{\pm}0.09$, $-0.15{\pm}0.08(^{\circ}C/sec)$. When compared with the normal eye group, the values of Ar.1, Ar.3, Ar.5 were significantly different in the dry eye group(p<0.05). The amount of temperature change, which was observed on the palpebral conjunctiva(Ar.1:central, Ar.2: nasal, Ar.3: temporal) of the normal eyes, measured by thermography, was $34.36{\pm}1.12$, $34.17{\pm}1.10$, $34.07{\pm}1.12^{\circ}C$ on each area. Same values taken from the dry eye group was $33.55{\pm}0.94$, $33.43{\pm}0.97$, $33.51{\pm}1.06^{\circ}C$ on each area. The values of Ar.1, taken from the dry eye group, had a significant difference, compared to the values of the normal eye group(p=0.05). Conclusion: The temperature of the ocular surface decreased faster on the dry eyes, compared to the normal eyes. The temperature measured on the palpebral conjunctiva of the dry eyes were also lower than the normal eyes. The temperature changes on the ocular surface, observed with a thermal camera, were objective values to assess the stability of tear films, and might provide useful data for studies related to dry eye syndrome.

• Journal of the Korean Geotechnical Society
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• v.22 no.6
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• pp.71-82
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• 2006

One of the most popular pre-reinforcement methods of tunnel heading in cohesionless soils would be the fore-polling of grouted pipes, known as RPUM (reinforced protective umbrella method) or UAM (umbrella arch method). This technique allows safe excavation even in poor ground conditions by creating longitudinal arch parallel to the tunnel axis as the tunnel advances. Some previous studies on the reinforcing effects have been performed using numerical methods and/or laboratory-based small scale model tests. The complexity of boundary conditions imposes difficulties in representing the tunnelling procedure in laboratory tests and theoretical approaches. Full-scale study to identify reinforcing effects of the tunnel heading has rarely been carried out so far. In this study, a large scale model testing for a tunnel in granular soils was performed. Reinforcing patterns considered are four cases, Non-Reinforced, Crown-Reinforced, Crown & Face-Reinforced, and Face-Reinforced. The behavior of ground and pipes as reinforcing member were fully measured as the surcharge pressure applied. The influences of reinforcing pattern, pipe length, and face reinforcement were investigated in terms of stress and displacement. It is revealed that only the Face-Reinforced has decreased sufficiently both vertical settlement in tunnel heading and horizontal displacement on the face. Vertical stresses along the tunnel axis were concentrated in tunnel heading from the test results, so the heading should be reinforced before tunnel advancing. Most of maximum axial forces and bending moments for Crown-reinforced were measured at 0.75D from the face. Also it should be recommended that the minimum length of the pipe is more than l.0D for crown reinforcement.