• 대한전자공학회논문지TC
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• 제44권3호
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• pp.92-97
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• 2007

스위칭 모우드 증폭기를 마이크로파 대역에서 이용하고자 하는 많은 연구가 있으며, 이러한 증폭기 중 E급 증폭기는 이론적으로 스위칭 동작을 통해 100%의 효율을 얻을 수 있다. 본 논문에서는 2.4GHz 대역 마이크로파 E급 증폭기로 출력 전력이 17.6dBm, 66%의 전력부가효율을 갖는 설계된 증폭기를 무선 랜 송신부에서 사용하기 위해 증폭기의 비선형 왜곡을 보상하고자 테이블 참조기법(Look Up Table)을 이용한 기저대역 사전왜곡 기법을 적용하였다. 설계된 증폭기는 -3dBm의 입력 무선랜신호를 인가하였을 때 출력스펙트럼 측정 결과가 IEEE 무선랜 스펙트럼 마스크 표준규격을 만족하며, 기저대역 사전왜곡을 적용하였을 때 중심주파수에서 20MHz offset인 주파수에서 최대 5dB의 ACPR 특성이 향상되었다.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2008년도 하계학술대회 논문집 Vol.9
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• pp.60-60
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• 2008

We manufactured Liquid Crystal Polymer (LCP) and (1-x)$BaTiO_3-xSrTiO_3$(BST) ceramic composites and investigated dielectric properties to use as embedded capacitor in printed circuit boards and replace LTCC substrates. The dielectric properties of these composites are varied with volume fraction of BST and ratios of BT/ST. Dielectric constants are in the range of 3~28. In addition, we could get low TCC and High Q value that could not achieve in other ceramic-polymer composites. Especially, in composite with x=0.4 and 50vol% BST, the dieletric constant and Q-value are 27 and 300, respectively. And more TCC is -116~145ppm/$^{\circ}C$ in the temperature range of -55~$125^{\circ}C$. We think that this composites can be used high-Q substrate material like LTCC and embedded temperature compensation capacitor in printed circuit boards.

• 대한화학회지
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• 제17권2호
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• pp.85-94
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• 1973

니트로 벤젠의 세가지 유도체, 즉 1.3.5-트리니트로벤젠(1.3.5-TNB), m-디니트로벤젠(m-DNB) 및 니트로벤젠(NB)등이 11종의 염기성 유기 용매 즉, ${\alpha}$-피콜린, 피리딘, 디메틸술포옥시드(DMSO), NN′-디메틸초산아미드(NN′-DMA), 테트라히드로퓨란(THF), 1,4-디옥산, 디에틸에테르, 시안화메틸, 프로필렌옥시드, 에피클로로히드린, 초산메틸등과 사염화탄소용액중에서 전하전이착물을 형성함을 자외선분광광도법에 의해 확인하고, 이들 전하전이착물의 안정도 상수를 결정하였다. Drago 와 Wayland 의 이중척도엔탈피식(double-scale-enthalpy)을 수정하여 $logK = E_AC_A+E_DC_D$식을 얻고, 이것을 써서 정전기적효과 $E_D$와 공유성효과 $C_D$값을 11종의 유기 용매에 대해 얻었다. 이 두 효과는 전하전이착물의 안정도 상수 K와 그리고 적외선 흡수 스펙트럼의 신축진동수변화 ${\Delta}{\nu}_C=O$에 영향을 주며, 특히 $C_D$ sms 안정도 상수에 비례하였고, 신축진동수변화 ${\Delta}{\nu}_{C=O}= 37.4-5.47E_D+12.1C_D$의 실험식을 얻었다. ${\pi}$결합을 가진 분자들이 전이착물을 이룰 때 정전기적효과와 공유성효과와 공유성효과가 모두 관여하며, 그밖에 결합하는 분자의 ${\pi}$궤도함수도 중요한 역할을 한다는 것을 알았다.

• Nutrition Research and Practice
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• 제18권1호
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• pp.1-18
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• 2024

BACKGROUND/OBJECTIVES: Endoplasmic reticulum (ER) stress in adipose tissue causes an inflammatory response and leads to metabolic diseases. However, the association between vitamin D and adipose ER stress remains poorly understood. In this study, we investigated whether 1,25-dihydroxyvitamin D₃ (1,25(OH)₂D₃) alleviates ER stress in adipocytes. MATERIALS/METHODS: 3T3-L1 cells were treated with different concentrations (i.e., 10-100 nM) of 1,25(OH)₂D₃ after or during differentiation (i.e., on day 0-7, 3-7, or 7). They were then incubated with thapsigargin (TG, 500 nM) for an additional 24 h to induce ER stress. Next, we measured the mRNA and protein levels of genes involved in unfold protein response (UPR) and adipogenesis using real-time polymerase chain reaction and western blotting and quantified the secreted protein levels of pro-inflammatory cytokines. Finally, the mRNA levels of UPR pathway genes were measured in adipocytes transfected with siRNA-targeting Vdr. RESULTS: Treatment with 1,25(OH)₂D₃ during various stages of adipocyte differentiation significantly inhibited ER stress induced by TG. In fully differentiated 3T3-L1 adipocytes, 1,25(OH)₂D₃ treatment suppressed mRNA levels of Ddit3, sXbp1, and Atf4 and decreased the secretion of monocyte chemoattractant protein-1, interleukin-6, and tumor necrosis factor-α. However, downregulation of the mRNA levels of Ddit3, sXbp1, and Atf4 following 1,25(OH)₂D₃ administration was not observed in Vdr-knockdown adipocytes. In addition, exposure of 3T3-L1 preadipocytes to 1,25(OH)₂D₃ inhibited transcription of Ddit3, sXbp1, Atf4, Bip, and Atf6 and reduced the p-alpha subunit of translation initiation factor 2 (eIF2α)/eIF2α and p-protein kinase RNA-like ER kinase (PERK)/PERK protein ratios. Furthermore, 1,25(OH)₂D₃ treatment before adipocyte differentiation reduced adipogenesis and the mRNA levels of adipogenic genes. CONCLUSIONS: Our data suggest that 1,25(OH)₂D₃ prevents TG-induced ER stress and inflammatory responses in mature adipocytes by downregulating UPR signaling via binding with Vdr. In addition, the inhibition of adipogenesis by vitamin D may contribute to the reduction of ER stress in adipocytes.

• 미생물학회지
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• 제50권1호
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• pp.73-83
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• 2014

단백질이 풍부한 식품을 고온 하에서 조리하는 과정 중에 주로 발생되는 돌연변이원 heterocyclic amines (HCAs)에 대한 유산균의 결합력 및 제거능을 조사하였다. 당 발효능 및 16S rRNA 염기서열 분석을 통해 동정된 19종의 유산균 중 Lactobacillus acidophilus D11, Enterococcus faecium D12, Pediococcus acidilactici D19, L. acidophilus D38, Lactobacillus sakei D44, Enterococcus faecalis D66 및 Lactobacillus plantarum D70의 세포이나 배양 상등액은 3-amino-1,4-dimethyl-5H-pyrido[4,3-b]indole (Trp-P-1)과 3-amino-1-methyl-5Hpyrido[4,3-b] indole (Trp-P-2)에 의한 Salmonella typhimurium TA98 및 TA100의 돌연변이 유발을 억제할 수 있었다. HCAs에 대한 유산균 세포의 결합력은 cell wall, exopolysaccharide 및 peptidoglycan 보다 높게 나타났다. 한편, 이들의 결합력은 단백질 분해효소, 가열, sodium metaperiodate 및 산 처리에 의해 유의하게 감소되었으므로 세포벽에 존재하는 당이나 단백질 성분이 이들 HCAs을 결합시키는데 중요한 역할을 하는 것으로 확인되었다. 또한 E. faecium D12, L. acidophilus D38 및 E. faecalis D66의 결합력은 SDS나 금속이온에 의해 감소되었으므로 이들세포와 돌연변이원 사이에는 이온 결합이나 소수성 결합이 작용하는 것으로 추정되었다. 한편, HCAs 결합력이 높은 L. acidophilus D38과 L. plantarum D70은 장관 상피세포에 대한 부착력이 낮으므로 돌연변이원을 세포에 결합시켜 체외로 배출함으로써 독성물질을 제거하는데 효과적인 것으로 확인되었다.

• 한국건축시공학회지
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• 제23권2호
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• pp.123-131
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• 2023

본 연구에서는 철근콘크리트의 피복두께, 산소확산속도, 철근직경의 총 세 가지 변수로 콘크리트 균열에 대한 해석을 실시하였다. 피복두께를 변수로 하였을 때 30, 40, 50mm의 피복두께에서 약 3년, 4년, 6년경과 후 균열이 발생하였고 산소확산속도를 변수로 하였을 때 2e-9, 2e-11, 2e-12(m²/s)의 산소확산도에서 약 4년, 5년, 10년경과 후 균열이 발생하였다. 철근직경의 경우 D10, D19, D25의 철근직경에서 약 4년, 3년, 2년경과 후 균열이 발생하였다.

• 생약학회지
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• 제4권4호
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• pp.193-203
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• 1973

The saponins of two- and four-year-old American ginseng plants (Panax quinquefolium L.) (Araliaceae) collected in July and September were studied. American ginseng saponins (panaquilins) differ from Korean ginseng $(Panax ginseng\;C.A.\;M_{EYER})$ saponins (ginsenosides). The American ginseng saponins separated and named were panaquilins A, B, C, D, E-1, E-2, E-3, G-1, G-2, (c) and (d). One-dimensional thin-layer chromatography did not completely separate panaquilin mixture and was subject to misinterpretation. The panaquilins were more accurately separated and identified by the two-dimensional thin-layer method established. Some differences in American ginseng saponins were dependent upon the plant age, time of collection, and part extracted. The American ginseng sapogenin components are panaxadiol (panaquilins B and C), oleanolic acid (panaquilin D) and panaxatriol (panaquilin G-1). The panaquilins E-1, E-2 and E-3 mixture contained both panaxadiol and panaxatriol. The genins of panaquilins A, (c), (d) and G-2 were not identified. In addition, ${\beta}-sitosterol$ and stigmasterol were identified from the root ether extracts.

• Toxicological Research
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• 제29권3호
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• pp.187-193
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• 2013

The effects of toluene in dimethylformamide (DMF)-induced hepatotoxicity were investigated with respect to the induction of cytochrome P-450 (CYP) and the activities of related enzymes. The rats were treated intraperitoneally with the organic solvents in olive oil (Single treatment groups: 450 [D1], 900 [D2], 1,800 [D3] mg DMF, and 346 mg toluene [T] per kg of body weight; Combined treatment groups: D1+T, D2+T, and D3+T) once a day for three days, while the control group received just the olive oil. Each group consisted of 4 rats. The activities of the xenobiotic metabolic enzymes and the hepatic morphology were assessed. The immunoblots indicated that the expression of CYP2E1 was considerably enhanced depending on the dosage of DMF and the CYP2E1 blot densities were significantly increased after treatment with both DMF and toluene, compared to treatment with DMF alone. The activities of glutathione-S-transferase and glutathione peroxidase were either decreased or remained unaltered after treatment with DMF and toluene, whereas the lipid peroxide levels were increased with increasing dosage of DMF and toluene. The liver tissue in the D3 group (1,800 mg/kg of DMF) showed signs of microvacuolation in the central vein region and a large necrotic zone around the central vein, in rats treated with both DMF (1,800 mg/kg) and toluene (D3T). These results suggest that the expression of CYP2E1 is induced by DMF and enhanced by toluene. These changes may have facilitated the accelerated formation of N-methylformamide (NMF) from toluene, and the generated NMF may directly induce liver damage.

• 한국통신학회논문지
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• 제40권8호
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• pp.1622-1630
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• 2015

본 연구에서는 원형편파를 양방향으로 복사하는 등각 스파이럴 안테나에 EBG(electromagnetic bandgap) 반사판을 사용하여 단일 방향으로 복사가 발생하게 하였다. EBG 반사판에서 스파이럴 암 까지의 높이가 가장 낮은 동작 주파수의 0.07 파장 높이로 한 경우, 원형편파의 축비가 손상되는 것이 발생하였다. 본 논문에서는, +z 방향에서의 동일 편파인 우선 원형 편파를 발생시키는 $E_{\theta},E_{\phi}$의 크기와 시간 위상차를 해석하여, 전 주파수 영역에서 축비를 개선하는 조건을 제시하였다. 그 결과, 3 ~ 10[dB] 주파수 범위에서 축비는 3[dB] 이하이고, 이득은 자유공간에서의 양방향 복사와 비교해서 약 3[dB] 정도 개선되었고, $S_{11}$은 전 주파수 영역에서 -10[dB]이하를 얻었다.

• 한국해양생명과학회지
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• 제3권2호
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• pp.81-86
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• 2018

The purpose of this study is to determine the effects of vibration on primary (e.g. plasma cortisol), secondary (e.g. plasma glucose, aspartate aminotransferase (AST), alanine aminotransferase (ALT), Na⁺, K⁺ and Cl^- and tertiary (e.g. mortality) stress responses in cultured eel, Anguilla japonica. For this purpose, three groups (including one control group and two stress groups) were set up. The control group was made exposed to vibration corresponding to 48 decibel (dB, V) (produced using electric vibrators) for 15 minutes per hour every day, and the two stress groups was made exposed to vibration corresponding to 58 and 68 dB (V) (produced using the same electric vibrators), equally, for 15 minutes per hour every day. Blood was sampled at day 0 (before starting vibration stress tests, BS), and days 1, 3, 5, 7, 9 and 11 (after starting vibration stress tests). As a result, plasma cortisol showed trend to continuously rise by consecutive stress from 4.1±0.1 ng/ml in BS. In 48 dB group (control), cortisol showed the highest level with 7.6±0.9 ng/ml after 7 days (p<0.05), but at 9 and 11 days was not significantly compared with BS level. In 58 dB group, the cortisol showed the highest level with 43.1±4.8 ng/ml after 1st day. Cortisol of 68 dB group increased significantly during the experimental period (14.4±2.3~32.0±5.7 ng/ml) (p<0.05). In 58, and 68 dB groups during the experimental period differed significantly compared to 48 group (p<0.05). Glucose in 48 dB were increased from 42.0 ±5.7 (BS) to 52.5±2.1 (1 day), the level was not significantly from 1 to 11 days. Glucose in 58 and 68 dB groups was increased significantly than BS during experimental period (p<0.05). K⁺ in 68 dB increased significantly (p<0.05) from 2.3±0.2 mE/ql (BS) to 3.3±0.5 mE/ql at 5 days. In 48 and 58 dB groups during the experimental period differed significantly (p<0.05). Na⁺ and Cl^- levels were not differed significantly during the experimental period. AST and ALT in 58 and 68 dB groups showed trend to continuously rise by consecutive stress. At 7 and 9 days in AST, between 48, 58 and 68 dB groups differed significantly (p<0.05). In 48, 58 and 68 dB groups at 1 day, blood hematocrit increased significantly higher than BS. The 11 days after vibration stress, the mortality in 48, 58 and 68 dB groups was 1.1, 5.1 and 5.8%, respectively. The present results have shown that A. japonica exhibited ''typical'' physiological responses when exposed to chronic vibration stress. These data suggested that chronic vibration stress caused substantial stress in the fish; especially the persisting elevated plasma AST and ALT levels observed would be expected to adverse effect. In conclusion, chronic vibration stress could greatly affects the hematological characteristics in A. japonica.