• 한국식품위생안전성학회지
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• 제14권1호
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• pp.76-83
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• 1999

Solid phase microextraction (SPME) was used for the determination of 6 standard solvents (methanol, isopropanol, methyl ethyl ketone, ethyl acetate, cyclohexane, toluene) in food packaging materials. SPME method is a solvent-free sample preparation technique in which a fused silica fiber coated with polymeric organic liquid is introduced into the headspace above the sample. SPME method using fiber coated polydimethylisiloxane (PDMS) was compared with static headspace (SHS) method used as a reference. It was found that the optimal adsorption condition using PDMS-SPME method was 2$0^{\circ}C$ for 15 minutes for the standard solvents. Detection limits, linearity, reproducibility and recovery of both SHS and PDMS-SPME methods have been determined using 6 standard solvents. Both methods were characterized by high reproducibility and good linearity. Using SHS methods, the mean recovery of the 6 standard solvents was ranged from 75.5% to 105.8% with a mean relative standard deviation (RSD) of 0.3% to 4.8%. With PDMS-SPME method, the mean recovery of the 6 standard solvents was ranged from 86.7% to 108.3% with a mean RSD of 0.4% to 2.5%. The detection limits of both methods were the same for toluene, cyclohexane and methyl ethyl ketone; those of PDMS-SPME method were higher than those of SHS method for methanol, isopropanol and ethyl acetate. PDMS-SPME fiber shoed excellent adsorption for non-polar solvents such as toluene, while it showed relatively low adsorption for polar solvents such as methanol.

• 미생물학회지
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• 제52권3호
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• pp.388-390
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• 2016

부식산(humic acid)을 이용하여 저온에서 배양된 Pedobacter sp. PAMC 27299는 남극 바톤 반도(Barton Peninsula) King George Island의 해안가 이끼(moss debris)로부터 분리되었다. 본 연구에서는 Pedobacter sp. PAMC 27299의 유전체 서열을 해독하였으며 크기 6,147,290 bp, G+C 함량 40.54%의 PAMC 27299는 지구 온난화 관련 저온적응 부식산 분해 효소를 보유하는 것으로 확인되었다.

• 한국해안해양공학회지
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• 제2권2호
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• pp.59-66
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• 1990

극지방의 해양 환경은 낮은 온도와 함께 여러 가지 형태로 존재하는 얼음의 분포에 의해 큰 영향을 받는다. 빙하와 빙산, 해빙 등 빙역학의 기초적인 이해를 위하여 본 연구는 polycrystalline ice의 재료적 특성과 파괴기구 등을 파악하고 극지 방하유동시 관측되는 creep 변경을 기술하기 위한 constitutive 모델을 제시하였다. 빙변형에 관여되는 여러 가지 물리적 변화 중 microcracking에 의한 재료의 손상을 주요인으로 간주하여 파손역학의 이론을 적용한 3차원 수치모델을 개발하였으며 기발표된 실험 결과와 비교하였다. 1축 균일압축을 받는 경우 실험 데이타와 수치모델은 유사한 거동을 보이고 있으며, 빙변형에 있어서 1, 2기 creep의 소성적 변형특성 뿐 아니라 microcracking에 의한3기(tertiary) creep의 특징까지도 잘 기술해 주고 있다.

• 분석과학
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• 제5권2호
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• pp.153-158
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• 1992

본 연구에서는 이동상 성질이 GC와 HPLC와는 전혀 다른 초임계 유체 크로마토그래피(SFC)를 사용함으로써 종래의 크로마토그래피의 방법으로는 분석하기 힘든 물질을 분석하는 방법을 개발하였다. GC로는 분리하기 힘든 긴 고리를 가진 Hydrocarbons이나 Mink Oils, Soybean oils 등이 SFC로 잘 분리될 수 있었다. 그 이유는 SFC에서는 시료가 갖고 있는 낮은 기화성이나 열에 불안정한 점 등이 이동상을 초임계 상태의 이산화탄소를 사용함으로써 극복되어질 수 있었다. 이 연구에서는 한걸음 더 나아가 극성이 강한 지방산 및 농약류를 분석하는 방법을 개발함으로써 SFC의 가장 큰 약점인 극성이 있는 시료의 처리 문제를 극복하고자 시도하였다.

• 천문학회보
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• 제36권2호
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• pp.145.1-145.1
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• 2011

We present results of two-color VR photometry of the intermediate polar RXS J1803. The data were aquired using the Korean 1-m telescope located at Mt. Lemmon, USA. Different "high" and "low" luminosity states, similar to other intermediate polars, were discovered. No statistically significant variability of the color index with varying luminosity was detected. The orbital variability was found to be not statistically significant. Spin maxima timings were determined, as well as the photometric ephemeris for the time interval of our observations. The spin period variations, caused by interaction of the accretion structure with the rotating magnetic white dwarf, were also detected. These variations are of complicated character, and their study requires further observations. We determine the color transformation coefficients for our photometric systems, and improve on the secondary photometric standards.

• 한국표면공학회지
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• 제39권3호
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• pp.142-146
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• 2006

A novel internal-type linear inductive antenna, which we refer to as a double comb-type antenna, was developed for a large-area plasma source with substrate size of $880\;mm{\times}660\;mm$ ($4^{th}$ generation glass size). In this study, effect of plasma confinement by applying multi-polar magnetic field was investigated. High density plasmas of the order of $3.18{\times}10^{11}\;cm^{-3}$ could be obtained with a pressure of 15 mTorr Ar at an inductive power of 5000 W with good plasma stability. This plasma density is higher than that obtained for the conventional double comb-type antenna, possibly due to the plasma confinement, low rf voltage, resulting in high power transfer efficiency. Also, due to the remarkable reduction in the antenna rf voltage and length, a plasma uniformity of less than 3% could be obtained within a substrate area of $880\;mm{\times}660\;mm$ as rf power increased.

• Ocean and Polar Research
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• 제32권3호
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• pp.321-329
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• 2010

Photosynthetic pigments, nutrients, and hydrographic variables were examined in order to elucidate the spatio-temporal variation of water column structure and its effect on phytoplankton community structure in the western channel of the Korea Strait in fall 2006 and spring 2007. High phytoplankton biomass in the spring was associated with high salinity, implying that nutrients were not supplied by coastal waters or the Yangtze-River Diluted water (YRDW) with low salinity. Expansion of the Korea Strait Bottom Cold Water (KSBCW) and a cold eddy observed during the spring season might enhance the nutrient supply from the subsurface layer to the euphotic zone. Chemotaxonomic examination showed that diatoms accounted for 60-70% of total biomass, followed by dinoflagellates. Nutrient supply by physical phenomena such as the expansion of the KSBCW and the occurrence of a cold eddy appears to be the controlling factors of phytoplankton community composition in the Korea Strait. Further study is needed to elucidate the mechanisms by which the KSBCW is expanded, and its role in phytoplankton dynamics.

• Current Applied Physics
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• 제18권12호
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• pp.1507-1512
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• 2018

The development of an organic-based aqueous redox flow battery (RFB) using quinone as an electroactive material has attracted great attention recently. This is because this battery is inexpensive, produces high energy density, and is environment friendly in stationary electrical energy storage applications. Herein, we investigate the redox potentials and solubilities of indole-5,6-quinone and indole-4,7-quinone derivatives in terms of the substituent effects of functional groups using theoretical calculations. Our results indicate that full-site substituted derivatives of indolequinone are more useful as active materials compared to single-site substituted derivatives. In particular, our calculations reveal that the substitution of $-PO_3H_2$ and $-SO_3H$ functional groups with multiple polar bonds is very effective in increasing the activity of the aqueous RFB. As a strategy to overcome the limitation that the aqueous solubility is intrinsically low because they are organic molecules, we suggest the substitution of functional groups with multiple polar bonds to the backbones of active organic materials. Among 180 indolequinone derivatives, 17 candidates that meet the redox potential standards ($${\leq_-}0.2V$$ or $${\geq_-}0.9V$$) and eight candidates with solubility exceeding 2 mol/L are identified. Three indolequinone derivatives that satisfy both conditions are finally presented as promising electroactive candidates for an aqueous RFB.

• 대한임베디드공학회논문지
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• 제18권4호
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• pp.185-194
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• 2023

Currently, drones are used in various fields such as transportation, agriculture and military. Especially, drones for military use are developed and utilized in many ways such as reconnaissance and bombing to minimize one's own damages. Nevertheless, they are developed as new weapons of modern types, so it is difficult to use them together with existing weapons. In this study, a drone program for effective bombing of mortar, which is often used in modern warfare, is developed. In mortar, a forward soldier comprehends the location of enemy for its distance and altitude, input them in data computer of launching angle, and applies the result value to cannon to launch. However, the existing method has low accuracy of bombing because observing shall be done within 1km from the target, and measuring accurate direction and velocity of the wind is difficult. Whereas, in the program of this study, the location of target, GPS, direction and velocity of the wind, and altitude are measured through drone. Each digit is used to calculate bombing specification for optimal bombing through the calculating formula of launching angle. In addition, when specifications are input in the program, the calculation is done automatically, so that it can be used in various mortars and shells. With the use of the program in this study, the location of enemy can be comprehended, and bombing specifications can be calculated quickly. It also enables the intensity of the wind to be applied for accurate bombing.

• Ocean and Polar Research
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• 제42권3호
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• pp.225-231
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• 2020

The aim of this study was to examine optimal induction method for carpospore release from Agarophyton vermiculophyllum cystocarps for seedling production. We tested the effects of environmental factors on carpospore release by using five different induction methods; spontaneous, desiccation, low temperature, desiccation+low temperature, and osmotic shock. Also, carpospores release was estimated at three temperatures (20, 25, and 30℃), and then under combinations of three day lengths (8, 12, and 16h) and two irradiances (30 and 60 μmol photons m^-2 s^-1), after pretreatment at desiccation+low temperature for 2 hr. The number of carpospores released was between 113 ~ 682 spores /cystocarp/day and it was maximal in the desiccation+low temperature treatment. Optimal environmental conditions for carpospore release of A. vermiculophyllum were 25℃, 16 h, and 60 μmol photons m^-2 s^-1. The present results suggest that massive carpospores for seedling production of A. vermiculophyllum could be obtained under a combination of 25℃, 16 h, and 60 μmol photons m^-2 s^-1 after pretreatment in the desiccation+low temperature.