• 한국전자통신학회논문지
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• 제16권4호
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• pp.599-604
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• 2021

무선인터넷의 수요가 급증하게 되면서 현재 사용하고 있는 2.4 및 5GHz 통신 대역은 포화상태에 도달하여 성능과 속도가 저하되고 있다. 따라서 본 논문에서는 향후 사용 가능한 10GHz 대역의 슬롯 패치 안테나 동작 특성을 설계 변수인 폭(W)과 길이(L), sL, sW, feed L, feed W를 변화시키며 HFSS(: High Frequency Structure Simulator)를 통해 분석하고 이를 바탕으로 설계된 안테나를 유전율 4.4의 FR-4 기판을 사용하여 슬롯 패치 안테나를 제작하였다. 제작된 안테나는 Network Analyzer를 이용하여 제작된 슬롯 패치 안테나의 주파수 동작 특성을 분석하였다. 제작된 슬롯 패치 안테나는 각각 중심주파수 10.23GHz, 반사손실 -32dB, -10dB 대역폭 420MHz으로 우수한 동작 특성을 보여주었다.

• Journal of Microbiology and Biotechnology
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• 제21권8호
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• pp.822-829
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• 2011

Evidence shows that probiotic bacteria can undergo substantial structural and morphological changes in response to environmental stresses, including antibiotics. Therefore, this study investigated the effects of penicillin G (0.015, 0.03, and 0.06 mg/l) on the morphology and adhesion of Lactobacillus acidophilus ATCC 4356, including the colony morphotype, biofilm production, hydrophobicity, $H_2_O2$ formation, S-layer structure, and slpA gene expression. Whereas only smooth colonies grew in the presence of penicillin, rough and smooth colony types were observed in the control group. L. acidophilus ATCC 4356 was found to be hydrophobic under normal conditions, yet its hydrophobicity decreased in the presence of the antibiotic. No biofilm was produced by the bacterium, despite testing a variety of different culture conditions; however, treatment with penicillin G (0.015-0.06 mg/l) significantly decreased its production of $H_2_O_2$ formation and altered the S-layer protein structure and slpA gene expression. The S-protein expression decreased with 0.015 mg/l penicillin G, yet increased with 0.03 and 0.06 mg/l penicillin G. In addition, the slpA gene expression decreased in the presence of 0.015 mg/l of the antibiotic. In conclusion, penicillin G was able to alter the S-layer protein production, slpA gene expression, and certain physicochemical properties of Lactobacillus acidophilus ATCC 4356.

• Bulletin of the Korean Chemical Society
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• 제31권8호
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• pp.2158-2162
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• 2010

Studies on the molecular construction and structures of $M(NO_3)_2$ (M = Cu(II), Ni(II)) complexes with 1,2-bis(dimethyl-3-pyridylsilyl)ethane (L) have been carried out. Formation of each molecular skeleton appears to be primarily associated with a suitable combination of bidentate N-donors of L and coordinating nature of octahedral metal(II) ions: [$Cu(NO_3)_2(L)_2$] yields a 2-dimensional sheet structure consisting of 44-membered $Cu_4L_4$ skeleton whereas $[Ni(L)_2(H_2O)_2](NO_3)_2$ produces an interpenetrated 3-dimensional structure consisting of 66-membered cyclohexanoid ($M_6L_6$) skeleton. The Cu(II) ion prefers nitrate whereas the Ni(II) ion prefers water molecules as the fifth and the sixth ligands.

• Bulletin of the Korean Chemical Society
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• 제34권5호
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• pp.1429-1434
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• 2013

A synthesis and cation-induced fluorescent behavior of the carbazole-attached $NO_2S_2$-macrocycle (L) is described and structurally characterized by single crystal X-ray analysis. The photoluminescence spectrum of L in 80% $CH_3CN/CH_2Cl_2$ displays a peak maximum at 431 nm (blue emission). In the metal-induced fluorometric experiment, L showed a drastic chelation-enhanced fluorescence quenching (CHEQ) effect only with $Hg^{2+}$ and $Cu^{2+}$. In ESI-mass study, a 1:1 stoichiometry for complexation of L with $Hg^{2+}$ was confirmed, suggesting the unique sensing behavior of the proposed ligand L due to the selective complexation affinity for $Hg^{2+}$. The observed results indicate that L is a promising turn-off type fluoroionophore for $Hg^{2+}$ and $Cu^{2+}$ detections. Additionally, the $Ag^+$ complex of the precursor macrocycle was prepared and its solid structure was crystallographically characterized.

• 한국정보통신학회:학술대회논문집
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• 한국해양정보통신학회 2007년도 추계종합학술대회
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• pp.863-867
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• 2007

본 논문은 Fractal 구조에 기초로 한 L-형 급전구조를 이용한 4세대 이동통신용 소형 마이크로스트립 패치 안테나를 설계하였다. 소형 안테나는 "Crossed-diagonal"라 불리는 특이한 형태의 공진 흐름이 존재함으로써 얻을 수 있다. 설계는 CST Microwave Studio 5.0으로 하였으며, 설계된 패치 안테나의 동작 특성으로서 입력 반사손실이 -10 [dB]이하 VSWR 2:1인 범위가 2.944 [GHz] ${\sim}$ 4.209 [GHz]까지 1.2647[GHz]의 35.4%라는 특성을 나타내었고, E-평면과 H-평면의 이득은 8.3dBi, 8.4dBi 그리고 3dB 빔폭은 E-평면에서 $40.6^{\circ}$ H-평변에서 $81.6^{\circ}$라는 시뮬레이션 결과를 각각 얻을 수 있었다.

• Bulletin of the Korean Chemical Society
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• 제15권11호
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• pp.940-944
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• 1994

The crystal structure of an ethylene sorption complex of dehydrated $Ag_{12}-A $reacted with bromine vapor has determined by single-crystal X-ray diffraction techniques in the cubic space group of Pm3m at 22(l)$^{\circ}$C (a=12.180(2) ${\AA}$). The crystal was prepared by dehydration of $Ag_{12}$-A at 400 $^{\circ}$C and $2 {\times} l0^{-6}$ Torr for 2 days, followed by exposure to 200 Torr of ethylene gas at 24(l) $^{\circ}$C for 1 hr. After the ethylene gas was evacuated for 1 hr, the crystal was exposed to 180 Torr of bromine vapor at 24(l) $^{\circ}$C for 1.5 h. The structure was refined to the final error indices, $R_1=0.066\;and\;R_2$ (weighted)=0.055, using 137 independent reflections for which I>3${\sigma}$I. About 55% of the sodalite unit contain two 6-ring $Ag^+$ ions and the remaining 45% contain $Ag_6$ molecules complexed to 2 $Ag^+$ ions at 6-ring sites to give $(Ag^+)_2(Ag_6).$ Upon sorption of ethylene, 4.75 ethylene molecules were sorbed per unit cell and of these, only 1.25 ethylene molecules were brominated by treatment of dibromine because of the limitation of the available space for the reaction products in the large cavity. In the large cavity, each of 3.5 $Ag^+$ ions forms a lateral ${\pi}$ complex with an ethylene molecule. About 2.5 8-ring $Ag^+$ ions per unit cell interact with 1.25 1,2-dibromoethane and each of ca. 1.25 6-ring $Ag^+$ ions also interacts with one of bromine atoms of 1,2-dibromoethane. Each bromine atom approaches a carbon atom with C-Br(l)=2.07(20) ${\AA}$ and C-Br(2)=2.07(10) ${\AA}$, respectively.

• 대한화학회지
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• 제47권4호
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• pp.427-431
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• 2003

• Bulletin of the Korean Chemical Society
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• 제22권6호
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• pp.647-650
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• 2001

• Molecules and Cells
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• 제41권4호
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• pp.331-341
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• 2018

L-pipecolic acid is a non-protein amino acid commonly found in plants, animals, and microorganisms. It is a well-known precursor to numerous microbial secondary metabolites and pharmaceuticals, including anticancer agents, immunosuppressants, and several antibiotics. Lysine cyclodeaminase (LCD) catalyzes ${\beta}$-deamination of L-lysine into L-pipecolic acid using ${\beta}$-nicotinamide adenine dinucleotide as a cofactor. Expression of a human homolog of LCD, ${\mu}$-crystallin, is elevated in prostate cancer patients. To understand the structural features and catalytic mechanisms of LCD, we determined the crystal structures of Streptomyces pristinaespiralis LCD (SpLCD) in (i) a binary complex with $NAD^+$, (ii) a ternary complex with $NAD^+$ and L-pipecolic acid, (iii) a ternary complex with $NAD^+$ and L-proline, and (iv) a ternary complex with $NAD^+$ and L-2,4-diamino butyric acid. The overall structure of SpLCD was similar to that of ornithine cyclodeaminase from Pseudomonas putida. In addition, SpLCD recognized L-lysine, L-ornithine, and L-2,4-diamino butyric acid despite differences in the active site, including differences in hydrogen bonding by Asp236, which corresponds with Asp228 from Pseudomonas putida ornithine cyclodeaminase. The substrate binding pocket of SpLCD allowed substrates smaller than lysine to bind, thus enabling binding to ornithine and L-2,4-diamino butyric acid. Our structural and biochemical data facilitate a detailed understanding of substrate and product recognition, thus providing evidence for a reaction mechanism for SpLCD. The proposed mechanism is unusual in that $NAD^+$ is initially converted into NADH and then reverted back into $NAD^+$ at a late stage of the reaction.

• 한국환경생태학회지
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• 제28권1호
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• pp.33-44
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• 2014

본 연구는 토함산습지 주변의 산림식생구조에 대해 알아보고자 토함산습지 주변을 지형적 관점에서 유역권을 설정하고 현존식생도를 작성하였다. 현존식생도를 바탕으로 대표되는 8개 군락, 즉, 소나무군락, 굴참나무군락, 신갈나무군락, 졸참나무군락, 신갈나무-졸참나무군락, 굴참나무-신갈나무-졸참나무군락, 층층나무군락, 버드나무군락에 대해 식생구조를 조사 분석하였다. 토함산 습지는 해발고 490m에 위치하고 있었으며 유역권의 면적은 약 $236,272m^2$이었다. 토함산 습지 유역권내 산림의 현존식생유형은 총 16개 유형으로 분류되었으며, 전체면적 중 신갈나무림이 $78,209.2m^2$로 전체 면적의 33.10%를 차지하고 있었다. 8개 군락의 구조를 알아보기 위해 조사구($10m{\times}10m$) 32개소를 설치하여 조사 분석 하였고, 각 군락별로 식생구조를 밝혔다. 본 조사지역의 산림식생 임령은 30~50년으로 추정되었으며, 토양산도(pH)는 4.89, 유기물함량은 4.46%로 조사되었다.