• Journal of the Korean Society for Precision Engineering
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• v.28 no.12
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• pp.1419-1424
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• 2011

Nanoimprint lithography is a next generation lithography technology, which enables to fabricate nano to micron-scale patterns through simple and low cost process. Nanoimprint lithography has been applied in various industry fields such as light emitting diodes, solar cells and display. Functional patterns, including anti-reflection moth-eye pattern, photonic crystal pattern, fabricated by nanoimprint lithography are used to improve overall efficiency of devices in that fields. For these reasons, in this study, sub-micron-scaled functional patterns were directly fabricated on Si and glass substrates by thermal imprinting process using ZnO nano-particles dispersion resin. Through the thermal imprinting process, arrays of sub-micron-scaled pillar and hole patterns were successfully fabricated on the Si and glass substrates. And then, the topography, components and optical property of the imprinted ZnO nano-particles/resin patterns are characterized by Scanning Electron Microscope, Energy-dispersive X-ray spectroscopy and UV-vis spectrometer, respectively.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.08a
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• pp.393-393
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• 2012

Optically active nanostructures such as subwavelength moth-eye antireflective structures or surface enhanced Raman spectroscopy (SERS) active structures have been demonstrated to provide the effective suppression of unwanted reflections as in subwavelength structure (SWS) or effective enhancement of selective signals as in SERS. While various nanopatterning techniques such as photolithography, electron-beam lithography, wafer level nanoimprinting lithography, and interference lithography can be employed to fabricate these nanostructures, roll-to-roll (R2R) nanoimprinting is gaining interests due to its low cost, continuous, and scalable process. R2R nanoimprinting requires a master to produce a stamp that can be wrapped around a quartz roller for repeated nanoimprinting process. Among many possibilities, two different types of mask can be employed to fabricate optically active nanostructures. One is self-assembled Au nanoparticles on Si substrate by depositing Au film with sputtering followed by annealing process. The other is monolayer silica particles dissolved in ethanol spread on the wafer by spin-coating method. The process is optimized by considering the density of Au and silica nano particles, depth and shape of the patterns. The depth of the pattern can be controlled with dry etch process using reactive ion etching (RIE) with the mixture of SF6 and CHF3. The resultant nanostructures are characterized for their reflectance using UV-Vis-NIR spectrophotometer (Agilent technology, Cary 5000) and for surface morphology using scanning electron microscope (SEM, JEOL JSM-7100F). Once optimized, these optically active nanostructures can be used to replicate with roll-to-roll process or soft lithography for various applications including displays, solar cells, and biosensors.

• International Journal of Industrial Entomology and Biomaterials
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• v.47 no.1
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• pp.44-50
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• 2023

The Daehwangjam has excellent marketability and quality. However, precise silkworm breeding data on the recent high-temperature environment is not enough collected, and it is necessary to check whether stable Daewhangjam silkworm egg production was possible in poor environments. In this study, the timing of metamorphosis of the Daewhangjam parents Jam323 and Jam324 silkworms, in an optimal condition and a general condition similar to breeding grounds, was investigated to confirm that appropriate mating was achieved. Surprisingly, a number of female moths were discarded due to the metamorphosis of Jam324 female moths much earlier than Jam323 male moths in either an optimal or a general condition. To improve this, during the Jam324 female pupation period, the mild low-temperature of 15℃ was treated for the pupation period to delay the metamorphosis into female moths. Depending on the treatment period, the metamorphosis of the female pupa was delayed by more than 4 days, allowing normal mating with the Jam323 male moth. The eye pigments in a pupa also slowly accumulated in these treatments. In order to discover the side effects of low-temperature treatments, the voltinism of the Daewhangjam eggs was investigated, but most of them remained univoltine. Taken together, the low-temperature treatment during the female pupation period made it possible to use Jam324 female moths that were should be discarded, which means that stable and efficient management of Daewhangjam egg production is possible.

• Korean Journal of Remote Sensing
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• v.36 no.5_1
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• pp.835-846
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• 2020

Recent severe climate changes and extreme weather events have caused the uncommon types of forest ecosystem disturbances such as hails and gypsy moths. This paper describes the analysis of the forest ecosystem disturbances using ISODATA (Iterative Self-organizing Data Analysis Technique Algorithm) with the RapidEye and Sentinel-2 images, regarding the cases of the hail damages in Hwasun in 2017 and the gypsy moth damages in the Chiak Mountain in 2020. In the case of hail damages, the comparison of the June image of this study and the July field survey of the previous study showed that the damage severity increased from June to July as the drought overlapped after the trees were injured by the hails. In the case of gypsy moths, significant leaf damages were found from the image of June, and the damages were mainly distributed at the low-altitude slope near Wonju City. We made sure that satellite remote sensing is a very effective method to detect various and unusual forest ecosystem disturbances caused by climate change. Also, it is expected that the Korean Medium Satellite for Agriculture and Forestry scheduled to launch in 2024 can be actively utilized to monitor such forest ecosystem disturbances.

• The Korean Journal of Pesticide Science
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• v.4 no.1
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• pp.38-43
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• 2000

As the first step of a research on the establishment of control strategy for grapevine diseases and insects, the current status of pest control and yield losses by them were surveyed from grapevine growers of Korea. For insects, the most difficult to control was a grapevine stem borer and a grapevine clearwing moth was the next. On the other hand, several diseases including anthracnose, downy mildew, powdery mildew, bird's eye rot, leaf blight, were answered by the growers. The occurrence of the pests varied to the cultural practices. Yield loss was more serious in rainfall intercept culture than in plastic film house culture and diseases caused more loss in yield than insects did. However, the grapevine grower's potential for the identification of the kinds of pests was not high enough. When the pest was observed, the growers consulted mainly with local pesticide dealers or neighbouring growers and usually applied the pesticides prescribed by the dealer. More than half of the growers did not use pest control calendar, and most of the growers applied pesticides before any symptom appeared. Also, more than half of the growers applied mixture of at least more than 1 kind of pesticide and nutrients. Insecticides were applied less than 5 times during the season, but it was more than 6 times for fungicides. In the pesticide selection, the growers checked control effect first, regardless of the registration, and the pest control cost per unit area varied very much depending on the growers.

• Korean journal of applied entomology
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• v.48 no.1
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• pp.87-94
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• 2009

KNI3126 which is the eco-friendly material made by plant extracts - neem and matrine - have been evaluated for efficacies against 6 main pests and toxicity on natural enemies. Insecticidal efficacies of KNI3126 against plant hopper were above 95% at 5 days after treatment (DAT), whereas pesticidal effects against the cotton aphid were above 95% at 3 DAT and slightly decreased at 5 DAT. Insecticidal efficacy against the palm thrips resulted in lower control value as 68.1% than that of chemical insecticides. KNI3126 showed more than 95% control value against diamond back moth, suggesting that it could suppress the population of pest hard to control as eco-friendly material. Mortalities against two-spotted spider mite were about 80% at 1 DAT and over 90% at 5 DAT, respectively. For evaluation of the toxicity on natural enemies, effect against predatory natural enemy was classified as moderate selective toxicity based on the criterion of International Organization of Bio-Control (IOBC), whereas against parasitic natural enemies was found to be relatively safe. Repellent effect was weak against plant hopper, but strong against two-spotted spider mite. In the toxicity test for safety, KNI3126 was classified as the lowest level at acute oral, acute dermal and fish toxicity test and did not induce the irritancy at skin irritation test and eye irritation test.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.10
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• pp.771-776
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• 2017

The cover glass of mobile displays and photovoltaic cells needs a functional coating, such as an anti-reflection and self-cleaning coating. Numerous studies have been conducted on the engineering application of biomimetic functional surfaces, such as moth eye and lotus leaf Anti-reflection coantings of silica nanoparticles could enhance the light transmittance. $TiO_2$ photocatalyst coatings have been applied to self-cleaning functional films. In this study, transparent hydrophobic anti-reflective coatings consisting of thin layers of $SiO_2/TiO_2$ nanoparticles were fabricated on a slide glass substrate by the sol-gel process and dip-coating process. The dependence of the surface morphology of the functional coatings was investigated by the atomic force microscopy (AFM), contact angle measurement, and UV-visible spectroscopy. It was found that the coating of $TiO_2$ nanoparticles exhibited a high average transmittance comparable to that of the bare slide glass substrate in the visible light range. The bi-layered functional coating of 7 nm $SiO_2$/7nm $TiO_2$ nanoparticles exhibits a transparent hydrophobic surface with a contact angle of $110^{\circ}$ and an improvement of the average transmittance of 2.3% compared to the bare slide glass substrate in the visible light range.