• 한국환경과학회지
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• 제12권11호
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• pp.1173-1179
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• 2003

Laboratory sorption isotherm batch studies have been attempted to elucidate interaction of synthetic pyrethroids (bifenthrin and permethrin) with sediments and their fractions. As a nonlinear isothermal model, the Freundlich equation was applied to sorption results obtained from sediments to investigate the relationship between synthetic pyrethroids and sediments containing different amounts of organic carbon. Results demonstrated that the sorption capabilities of bifenthrin and cis- and trans-permethrin was in the order of bifenthrin, cis-permethrin and trans-permethrin, respectively, indicating that adsorbed bifenthrin was the most stable followed by cis- and trans-permethrin in all sediments. Their sorption capability was closely related to organic carbon contents in sediments. Higher sorption was observed in sediments containing higher organic carbon contents. Sorption study extended into the fractions, clay and humic acids, extracted from a sediment, indicated that higher sorption capacity in humic acids occurred than in the clay of both examined bifenthrin and permethrin. This study demonstrates the sorption of synthetic pyrethroids with sediments, and will help in the understanding of the transport and fate of synthetic pyrethroids existing in field sediments.

• 한국콘텐츠학회논문지
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• 제21권6호
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• pp.218-227
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• 2021

본 연구는 국내에서 유학생들의 현황에 대한 통계 결과를 공시하기 시작한 2004년부터 16년 간 중국인 유학생 관련 뉴스 데이터를 수집하였으며, 그 중 코로나19 확산이 심화되어 팬데믹 상황으로 정의되는 2020년의 뉴스데이터를 선별하여 LDA 분석을 통해 최적 토픽 11개를 도출하여 연간 주요 사건들과의 관계를 중심으로 탐색적 차원에서 분석하였다. 분석 결과, 2020년 중국인 유학생에 대한 뉴스는 코로나바이러스 상황에 대한 이슈에만 집중적으로 연결하여 보도하는 경향이 있었으며 감염 확산의 원인 관련어 등 부정적인 이슈와 연결되어 있음을 확인하였다. 국민들의 소통을 매개하는 언론에서 외국인 혐오 담론과 중국인 유학생 보도가 무관하지 않다는 점에서 팬데믹 상황 속 외국인에 대한 혐오가 팽배한 오늘날 국민 간 소통을 매개하는 언론이 중국인 유학생에 대한 보도 방향에 신중할 필요가 있음을 밝혔다.

• Journal of Photoscience
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• 제9권2호
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• pp.51-54
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• 2002

We propose a novel mechanism (Twist Sharing Mechanism) for the cis-trans photoisomerization of rhodopsin, based on the molecular dynamics (MD) simulation study. New things devised in our simulations are (1) the adoption of Mt. Fuji potentials in the excited state for twisting of the three bonds C9=C10, C11=C12 and C13=14 which are modeled using the detailed ab initio quantum chemical calculations and (2) to use the rhodopsin structure which was resolved recently by the X-ray crystallographic study. As a result, we found the followings: Due to the intramolecular steric hindrance between 20-methyl and 10-H in the retinal chromophore, the C12-C13 and C10-C11 bonds are considerably twisted counterclockwise in rhodopsin, allowing only counterclockwise rotation of the C11 =C12 in the excited state. The movement of 19-methyl in rhodopsin is blocked by the surrounding three amino acids, Thr 118, Met 207 and Tyr 268, prohibiting the rotation of C9=C10. As a result only all-trans form of the chromophore is obtainable as a photoproduct. At the 90$^{\circ}$ twisting of C11=C12 in the course of photoisomerization, twisting energies of the other bonds amount to about 20 kcal/mol. If the transition state for the thermal isomerization is assumed to be similar to this structure, the activation energy for the thermal isomerization around C11=C12'in rhodopsin is elevated by about 20 kcal/mol and the thermal isomerization rate is decelerated by 10$\^$-14/ times than that of the retinal chromophore in solution, protecting photosignal from the thermal noise.

• Bulletin of the Korean Chemical Society
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• 제29권3호
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• pp.541-545
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• 2008

Stable molecular isomers were calculated for the azobenzene crown ether p-tert-butylcalix[4]arene (1) in the host and their alkali-metal-ion complexes. The structures of two distinct isomers (cis and trans) have been optimized using DFT B3LYP/6-31G(d,p) method. Trans isomer of 1 is found to be 11.69 kcal/mol more stable than cis analogue. For two different kinds of complexation mode, the alkali-metal-cation in the crown-ether moiety (exo) has much better complexation efficiency than in the benzene-rings (endo) pocket for both isomers of 1. Sodium ion has much better complexation efficiency than potassium ion in all kinds of complexation mode with host 1. The Na+ complexation efficiency of the trans-complex (1) in the exo-binding mode is 8.24 kcal/mol better than cis-exo analogue.

• Bulletin of the Korean Chemical Society
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• 제25권7호
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• pp.977-982
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• 2004

The reaction of $cis-[Cr([14]-decane)(OH_2)_2]^+$ ([14]-decane = rac-5,5,7,12,12,14-hexamethyl-1,4,8,11-teraazacyclotetradecane) with auxiliary ligands {$L_a$ = benzoate(bz) or chlorobenzoate(cbz)} leads to a new compound $[Cr([14]-decane)(bz)_2]ClO_4$ or $[Cr([14]-decane)(cbz)_2]ClO_4$. These complexes have been characterized by a combination of elemental analysis, conductivity, IR and Vis spectroscopy, mass spectrometry, and X-ray crystallography. The crystal structure of $[Cr([14]-decane)(cbz)_2]^+$ was determined. The complex shows a distorted octahedral coordination environment with the macrocycle adopting a folded cis-V conformation. The angle $N_{axial}-Cr-N_{axial}$ deviates by $14.5^{\circ}$ from the ideal value of $180^{\circ}$for a perfect octahedron. The bond angle cis-O-Cr-O between the Cr(III) ion and the two carboxylate oxygen atoms of the monodentate p-chlorobenzoate ligands is close to 90$^{\circ}$. The FAB mass spectra of the $cis-[Cr([14]-decane)(La)_2]ClO_4$ display peaks due to the molecular ions $[Cr([14]-decane)(bz)_2-H]^\;,\;[Cr([14]-decane)(cbz)_2-2H]^$ at m/z 578, 646, respectively.

• JSTS:Journal of Semiconductor Technology and Science
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• 제17권1호
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• pp.110-119
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• 2017

This paper describes a CMOS image sensor (CIS) with dual correlated double sampling (CDS) and column-parallel analog-to-digital converter (ADC) and its measurement method using a field-programmable gate array (FPGA) integrated module. The CIS is composed of a $320{\times}240$ pixel array with $3.2{\mu}m{\times}3.2{\mu}m$ pixels and column-parallel 10-bit single-slope ADCs. It is fabricated in a $0.11-{\mu}m$ CIS process, and consumes 49.2 mW from 1.5 V and 3.3 V power supplies while operating at 6.25 MHz. The measured dynamic range is 53.72 dB, and the total and column fixed pattern noise in a dark condition are 0.10% and 0.029%. The maximum integral nonlinearity and the differential nonlinearity of the ADC are +1.15 / -1.74 LSB and +0.63 / -0.56 LSB, respectively.

• Journal of Microbiology and Biotechnology
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• 제14권6호
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• pp.1217-1226
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• 2004

A psychrotrophic bacterial strain, Pseudomonas fluorescens BM07, synthesized unsaturated fatty acids (UFA) from fructose in response to lowering of growth temperature, and incorporated them into both polyhydroxyalkanoic acid (PHA) and membrane lipid. The blocking of PHA synthesis by adding 5 mM 2-bromooctanoic acid to the growth medium, containing 70 mM fructose, was found to be a useful means to profile the composition of membrane lipid by gas chromatography. As the growth temperature changed from 35 to $50^{\circ}C$, the total content of two UFA, 3-hydroxy-cis-5­dodecenoic acid ($C_{12:1}$) and 3-hydroxy-cis-7-tetradecenoic acid ($C_{14:1}$), in PHA increased from 31 to 44 $mol\%$. The growth at lower temperatures also led to an increase in the level of two major UFA, palmitoleic acid (C16:1 cis9) and cis-vaccenic acid (C18:1 cis11), in membrane lipid. A fraction of these membrane-lipid UFA was converted to their corresponding cyclopropane fatty acids (CFA). The CFA conversion was a function of culture time, exhibiting biphasic increase before and after entering the stationary phase. However, pH changes in growth media had no effect on the CFA conversion, which is contrary to the case of E. coli reported. The cells grown at $30^{\circ}C$ responded to a cold shock (lowering the medium temperature down to $10^{\circ}C$) by increasing the level of C16:1 cis9 and C 18: I cis II up to that of $10^{\circ}C$-grown control cells and concomitantly decreasing the relative level of cis-9,10­methylenehexadecanoic acid (the CFA converted from C16:1 cis9) from 14 to 8 $mol\%$, whereas the 10-grown cells exhibited little change in the lipid composition when exposed to a warmer environment of $30^{\circ}C$ for 12 h. Based on this one- way response, we suggest that this psychrotrophic strain responds more efficiently and sensitively to a cold shock than to a hot shock. It is also suggested that BM07 strain is a good producer of two unsaturated 3-hydroxyacids, $C_{12:1}\;and\;C_{141:1}$.

• Asian-Australasian Journal of Animal Sciences
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• 제18권10호
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• pp.1425-1429
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• 2005

Megaspahera elsdenii YJ-4, which was previously isolated as a producer of trans-10, cis-12 CLA, was studied for its carbon source on the CLA production. M. elsdenii YJ-4, was incubated with glucose and lactose, and cultured in batch and continuous culture systems with linoleic acid at various pHs to investigate CLA production. Batch cultures of the ruminal bacterium, M. elsdenii YJ-4, were resistant to stearic acid and linoleic acid, and little growth inhibition was observed even when the fatty acid concentration in the culture was as much as 4 mg $ml^{-1}$. Stationary phase batch cultures (0.25 mg bacterial protein $ml^{-1}$) that had been grown on lactate and incubated with linoleic acid (0.20 mg $ml^{-1}$) produced approximately 12 ${\mu}g$ trans-10, cis-12 CLA mg $protein^{-1}$ and little cis-9, trans-11 CLA was detected. Some linoleic acid was converted to hydrogenated products (chiefly stearic acid), but these fatty acids were less than 5 ${\mu}g$ mg bacterial $protein^{-1}$. Stationary phase batch cultures that had been grown on glucose produced at least 3-fold less trans-10, cis-12 CLA than ones grown on lactate. Cells from lactate-limited continuous cultures produced less trans-10, cis-12 CLA than those from batch culture, but only if the pH was greater than 6.4. When the pH of the lactate-limited continuous cultures was lower than 6.4, trans-10, cis-12 CLA and hydrogenated products declined. Cells from glucose-limited continuous cultures produced less trans-10, cis-12 CLA and hydrogenated products than the cells that had been limited by lactate, but pH had little impact on this production. These results support the idea that M. elsdenii YJ-4 could be one of the major producers of trans-10, cis-12 CLA which causes cows to produce milk with a low fat content.

• 한국약용작물학회지
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• 제9권2호
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• pp.108-115
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• 2001

국내에서 자생하고 있는 만수국아재비의 정유함량 및 구성성분 조성을 조사하기 위하여 전남 고흥과 전북 부안지역에서 수집한 다음 수증기 증류법으로 분리한 정유의 함량은 각각 0.52%와 0.48%이었다. 얻어진 정유로부터 GC, GC-MS 및 문헌상의 Rl값과 비교에 의해 69종의 성분을 동정하였으나 monoterpene, sesquiterpene 및 sesquiterpene alcohol류가 많이 검출되었다. 동정된 성분들 중 GC peak 면적비를 기준으로 함유비율이 높은 성분은 limonene, $cis-{\beta}-ocimene$, diydrotagetone, trans-tagetone, cis-tagetone, trnas-tagetenone 및 cis-tagetenone 등이었다. Limonene의 함유비율은 전남 고흥과 전북 부안에서 수집한 만수국아재비의 정유에서 각각 6.41%와 5.83% 로서 두 시료간에 큰 차이가 없었으나 $cis-{\beta}-ocimene$은 고흥에서 수집한 시료의 정유에서 47.73%인 반면 부안에서 수집한 시료의 정유에서는 4.87%를 차지하였고, dihydrotagetone의 경우 고흥에서 수집한 시료의 정유에서는 14.78%인 반면 부안에서 수집한 시료의 정유에서는 52.83%로서 시료간에 큰 차이를 보였다. 또한 trans-tagetone과 cis- tagetone은 고흥지역보다는 부안지역에서 수집한 시료의 정유에서 높은 반면 trans-tagetenone과 cis-tagetenone은 부안 지역보다는 고홍지역에서 수집한 시료의 정유에서 함유비율이 높았다.

• JSTS:Journal of Semiconductor Technology and Science
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• 제11권3호
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• pp.182-189
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• 2011

In this work, a tunneling field-effect transistor (TFET) based on heterojunctions of compound and Group IV semiconductors is introduced and simulated. TFETs based on either silicon or compound semiconductors have been intensively researched due to their merits of robustness against short channel effects (SCEs) and excellent subthreshold swing (SS) characteristics. However, silicon TFETs have the drawback of low on-current and compound ones are difficult to integrate with silicon CMOS circuits. In order to combine the high tunneling efficiency of narrow bandgap material TFETs and the high mobility of III-V TFETs, a Type-I heterojunction tunneling field-effect transistor (I-HTFET) adopting $Ge-Al_xGa_{1-x}As-Ge$ system has been optimized by simulation in terms of aluminum (Al) composition. To maximize device performance, we considered a nanowire structure, and it was shown that high performance (HP) logic technology can be achieved by the proposed device. The optimum Al composition turned out to be around 20% (x=0.2).