• 한국재료학회지
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• 제29권8호
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• pp.469-476
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• 2019

A lead-free bulk ceramic having a chemical formula $Ba_{0.8}Ca_{0.2}(Ti_{0.8}Zr_{0.1}Ce_{0.1})O_3$ (further termed as BCTZCO) is synthesized using mixed oxide route. The structural, dielectric, impedance, and conductivity properties, as well as the modulus of the synthesized sample are discussed in the present work. Analysis of X-ray diffraction data obtained at room temperature reveals the existence of some impurity phases. The natural surface morphology shows close packing of grains with few voids. Attempts have been made to study the (a) effect of microstructures containing grains, grain boundaries, and electrodes on impedance and capacitive characteristics, (b) relationship between properties and crystal structure, and (c) nature of the relaxation mechanism of the prepared samples. The relationship between the structure and physical properties is established. The frequency and temperature dependence of the dielectric properties reveal that this complex system has a high dielectric constant and low tangent loss. An analysis of impedance and related parameters illuminates the contributions of grains. The activation energy is determined for only the high temperature region in the temperature dependent AC conductivity graph. Deviation from the Debye behavior is seen in the Nyquist plot at different temperatures. The relaxation mechanism and the electrical transport properties in the sample are investigated with the help of various spectroscopic (i.e., dielectric, modulus, and impedance) techniques. This lead free sample will serve as a base for device engineering.

• 대한본초학회지
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• 제27권6호
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• pp.1-6
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• 2012

Objectives : ROS are involved in a wide spectrum of diseases including chronic inflammation and cancer. S.chinensis Baill, a perennial herb commonly called Chinese lizard's tail or Sam-baek-cho in Korea, is used for the treatment of edema and inflammatory diseases in the Oriental folk medicine. In this study, we investigated the antioxidant activities and anti-inflammatory effects of the two extracts, water(WE) and ethyl acetate(EAE) from S.chinensis Baill. Methods : Anti-oxidant activity was evaluated using Fe2+ chelating and hydroxyl radical scavenging assay. DNA cleavage assay, and western blot and immunostaining for phospho-p65 were performed to evaluate anti-oxidative effect. Anti-inflammatory effect was performed using NO generation assay and western blot in LPS-stimulated RAW264.7 cell. Results : In Fe2+ chelating activity and hydroxyl radical scavenging activity, WE showed more strong scavenging activity for hydroxyl radical than EAE. WE scavenged hydroxyl radical by 12% at 3.2 ${\mu}g/ml$, 21% at 16 ${\mu}g/ml$, 32% at 80 ${\mu}g/ml$, 66% at 400 ${\mu}g/ml$ and 82% at 2000 ${\mu}g/ml$, respectively. In addition, WE showed more strong chelating activity than EAE. WE chelated Fe2+ ion by 1.1% at 3.2 ${\mu}g/ml$, 8.2% at 16 ${\mu}g/ml$, 26.3% at 80 ${\mu}g/ml$, 72% at 400 ${\mu}g/ml$ and 89% at 2000 ${\mu}g/ml$, respectively. Also, WE inhibited oxidative damage via its anti-oxidant activity. In anti-inflammatory effect, EAE inhibited NO production and iNOS expression. In addition EAE suppressed the NF-${\kappa}B$ and MAPK signaling pathway in LPS-stimulated RAW 264.7 cells. Conclusions : Together, these data indicate that S. chinensis Baill, shows anti-oxidant activity and anti-inflammatory effect.

• 한국직업건강간호학회지
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• 제33권1호
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• pp.26-35
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• 2024

Purpose: This study aumed to identify the effects of job satisfaction, nursing organizational culture and social support on intention retention among general hospital nurses. Methods: The subjects were 254 nurses working in one general hospital. Data were collected from January 1 to 30, 2023. Data were analyzed by t-test, ANOVA, Pearson correlation, and multiple regression analysis using the SPSS/WIN 25.0 program. Results: (a) In this study, the mean value of job satisfaction was 3.07±0.43, relation-oriented culture was 3.45±0.51, hierarchy-oriented culture was 3.39±0.49, task-oriented culture was 3.35±0.48, innovation-oriented culture was 3.00±0.46, social support was 3.75±0.49, and intention retention was 4.98±1.39. (b) Intention retention had a positive correlation with job satisfaction (r=.41, p<.001), social support (r=.29, p<.001), innovation-oriented culture (r=.29, p<.001), relation-oriented culture (r=.20, p=.001), and hierarchy-oriented culture (r=.18, p=.002). (c) Factors that affect intention retention include job satisfaction (β=.41, p<.001), Working type (Non-shift) (β=.18, p=.001), Nursing job selection (Recommendation, employment) (β=-.16, p=.003), and the explanation power was 23.1% (F=9.43, p<.001). Conclusion: Our study shows that job satisfaction plays a significant role in the intention retention of nurses. It is important to strengthen job satisfaction to increase the retention of nurses. The results of this study may serve as basic data for the development of strategies to improve intention retention in nurses.

• The Plant Pathology Journal
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• 제40권5호
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• pp.525-536
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• 2024

Agrochemicals containing antibiotics are authorized to manage fire blight that has been occurring in Korea since 2015. The minimum inhibitory concentration (MIC) of each antibiotic against Erwinia amylovora, the causal pathogen of fire blight, has increased over the years due to the pathogen's frequent exposure to antibiotics, indicating the necessity to prepare for the emergence of antibiotic resistance. In this study, E. amylovora was exposed to stepwise increasing concentrations of eight different agrochemicals, each containing single or mixed antibiotics, and gene mutation and changes in MIC were assessed. Streptomycin and oxolinic acid induced an amino acid substitution in RpsL and GyrA, respectively, resulting in a rapid increase in MIC. Oxytetracycline initially induced amino acid substitutions or frameshifts in AcrR, followed by substitutions of 30S small ribosomal protein subunit S10 or AcrB, further increasing MIC. E. amylovora acquired resistance in the order of oxolinic acid, streptomycin, and oxytetracycline at varying exposure frequencies. Resistance acquisition was slower against agrochemicals containing mixed antibiotics than those with single antibiotics. However, gene mutations conferring antibiotic resistance emerged sequentially to both antibiotics in the mixed formulations. Results suggested that frequent application of mixed antibiotics could lead to the emergence of multidrug-resistant E. amylovora isolates. This study provided essential insights into preventing the emergence of antibiotic-resistant E. amylovora and understanding the underlying mechanisms of resistance acquisition.

• 미생물학회지
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• 제52권4호
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• pp.428-436
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• 2016

항균제에 대한 내성 증가는 국내뿐만 아니라 세계적으로도 인류 건강에 큰논란이 되고 있다. 박테리아에 의한 감염을 치료하기 위해 같은 혹은 다른 계열의 항생제에 순차적으로 노출된다. 따라서, 본 연구는 ciprofloxacin과 meropenem의 순차적 처리에 따른 폐렴간균(Klebsiella pneumoniae)의 생육, 항생제 민감성, 돌연변이 빈도, ${\beta}$-lactamase activity, 생물막 형성 및 내성 관련 유전자 발현을 평가하기 위해 설계되었다. 처리군은 대조군(control; CON), 1/2 MIC ciprofloxacin (1/2CIP), 2 MIC ciprofloxacin (2CIP), 1/2 MIC ciprofloxacin+1/2 MIC meropenem+2 MIC ciprofloxacin (1/2CIP-1/2MEM-2CIP), 1/2 MIC ciprofloxacin+1/2 MIC meropenem+2 MIC meropenem(1/2CIP-1/2MEM-2MEM), 1/2 MIC ciprofloxacin+2 MIC ciprofloxacin+2 MIC meropenem (1/2CIP-2CIP-2MEM)을 포함한다. 24시간의 배양 동안 2CIP처리군에서 K. pneumoniae의 생육이 관찰되지 않았다. 모든 처리군에서 planktonic cell의 수는 7에서 10 log CFU/ml의 유의적인 차이를 보였으나 biofilm cell의 수는 7 log CFU/ml로 비슷하였다. 돌연변이 빈도는 1/2CIP-1/2MEM-2CIP에서 가장 낮은 14%을 보였다. 대조군과 비교하여 1/2CIP-2CIP-2MEM 처리 K. pneumoniae는 piperacillin, cefotaxime, nalidixic에 대한 민감도가 감소되었다. 1/2CIP-1/2MEM-2CIPrk 가장 높은 ${\beta}$-lactamase activity(22 nmol/min/ml)을 보인 반면 1/2CIP-2CIP-2MEM은 가장 낮은 ${\beta}$-lactamase activity (6 nmol/min/ml)을 보였다. Multidrug efflux pump 관련 유전자(acrA, acrB, and ramA)의 발현은 1/2CIP-1/2MER-2MER and 1/2CIP2CIP-2MER 처리된 K. pneumoniae에서 2배 이상 증가하였다. 따라서 순차적 항생제의 처리는 K. pneumoniae의 항생제 내성 양상을 변화시킬 수 있다.

• 동아시아식생활학회지
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• 제27권2호
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• pp.235-242
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• 2017

본 연구에서는 국화과에 속하는 Chrysanthemum indicum L.(CI)의 70% EtOH 추출물 및 분획물(dichloromethane, ethyl acetate 및 H2O)의 폴리페놀 함량, 플라보노이드 함량, 항산화 활성 및 생리활성을 평가하였다. 항산화 활성으로는 DPPH, ABTS 및 superoxide 소거 활성을 확인하였고, 생리활성 평가는 ${\alpha}$-glucosidase와 PTP1B 저해 활성을 측정하였다. 그 결과, CI 70% EtOH 추출물에서 폴리페놀과 플라보노이드의 함량은 각각 30.20 mg 및 31.58 mg인 것으로 확인되었다. 여러 분획물 중 EA 분획물이 폴리페놀(87.87 mg)과 플라보노이드(65.12 mg)의 함량이 가장 높았다. EA 분획물의 DPPH, ABTS 및 SOD 소거능은 각각 93.84%, 93.38% 및 84.68%의 억제를 나타냈다. EA 분획물은 70% EtOH 추출물 및 다른 분획과 비교하여 가장 높은 항산화 활성을 보였다. 또한 EA 분획물($20{\mu}g/mL$)의 ${\alpha}$-glucosidase 및 PTP1B 억제 결과는 다른 시료에 비해 각각 30.29% 및 99.24%의 가장 높은 억제를 나타내었다. 본 연구 결과를 통해 감국의 EA 분획물이 70% EtOH 추출물 및 다른 분획물보다 많은 항산화 및 항당뇨 성분을 함유하는 것으로 보여진다. 결론적으로 우리는 CI의 천연 항산화 물질 및 기능성 물질에 성능이 좋아 화장품 첨가제나 음료로도 개발이 가능할 수 있을 것으로 사료된다.

• 한국토양비료학회지
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• 제46권6호
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• pp.659-664
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• 2013

The aim of this study is to determine the drought stress index through photochemical analysis in red pepper (Capsiumannuum L.). The photochemical interpretation was performed in the basis of the relation between Kautsky effect and Photosystem II (PSII) following the measurement of chlorophyll, pheophytin contents, and $CO_2$ assimilation in drought stressed 5-week-old red pepper plants. The $CO_2$ assimilation rate was severely lowered with almost 77% reduction of chlorophyll and pheophytin contents at four days after non-irrigation. It was clearly observed that the chlorophyll fluorescence intensity rose from a minimum level (the O level), in less than one second, to a maximum level (the P-level) via two intermediate steps labeled J and I (OJIP process). Drought factor index (DFI) was also calculated using measured OJIP parameters. The DFI was -0.22, meaning not only the initial inhibition of PSII but also sequential inhibition of PSI. In real, most of all photochemical parameters such as quantum yield of the electron transport flux from Quinone A ($Q_A$) to Quinone B ($Q_B$), quantum yield of the electron transport flux until the PSI electron acceptors, quantum yield of the electron transport flux until the PSI electron acceptors, average absorbed photon flux per PSII reaction center, and electron transport flux until PSI acceptors per cross section were profoundly reduced except number of QA reducing reaction centers (RCs) per PSII antenna chlorophyll (RC/ABS). It was illuminated that at least 6 parameters related with quantum yield/efficiency and specific energy fluxes (per active PSII RC) could be applied to be used as the drought stress index. Furthermore, in the combination of parameters, driving forces (DF) for photochemical activity could be deduced from the performance index (PI) for energy conservation from photons absorbed by PSII antenna until the reduction of PSI acceptors. In conclusion, photochemical responses and their related parameters can be used as physiological DFI.

• 대한전자공학회논문지SD
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• 제42권11호
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• pp.33-40
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• 2005

본 논문에서는 지상파 DMB 단말기 모뎀의 핵심 기능블록으로 사용되는 FFT/IFFT 코어(FFT256/2k)를 설계하였다. 설계된 코어는 Eureka-147 전송 규격에 명시된 4가지 전송모드를 지원할 수 있도록 256/512/1204/2048점 FFT/IFFT를 선택적으로 수행하도록 설계되었다. R2SDF와 R2SDC 구조를 혼합하여 적용함으로써 메모리 용량을 최소화 하였으며, R2SDC 단일 구조로 구현한 경우에 비해 메모리 크기를 약 $62\%$ 감소시켰다. 또한 TS_CBFP(Two Step Convergent Block Floating Point)를 사용하여 SQNR를 향상시켰으며, 50MHz(a)2.5-V로 동작하는 경우 2048점 FFT/IFFT 연산에 $41-\;{\mu}s$가 소요되었다 Verilog-HDL로 설계된 코어는 $0.25-\;{\mu}m$ CMOS Cell 라이브러리로 합성한 결과 약 68,400개의 게이트와 58,130 비트의 메모리로 구현되었으며, switching activity를 산출하여 전력소모를 측정한 결과 2048점 FFT의 경우 113-mW의 전력을 소모하는 것으로 추정되었다. 설계된 코어를 FPGA에 구현하여 동작시킨 결과 정상 동작을 검증하였으며, 전체 평균 50-dB 이상의 SQNR 성능을 보였다.

• 한국환경보건학회지
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• 제36권1호
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• pp.52-60
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• 2010

High performance liquid chromatography (HPLC) and liquid chromatography mass spectrometry (LC/MS) have been widely used to quantify aflatoxins in food, but these methods are expensive, time-consuming, unsuitable for analysis of the routine screening of large sample numbers and require derivatization and high level techniques to perform. The objective of this study is to detect aflatoxins in a large number of foods by a high efficient analytical system of combined enzyme linked immunosorbent assay (ELISA) for screening and LC/MS/MS for confirmation. The samples spiked individually with aflatoxin $B_1$ (0.5 and 1.0 ng/g) and total aflatoxins (10 ng/g) were analyzed by ELISA and LC/MS/ MS, and the recoveries for ELISA and LC/MS/MS were 71.8~119.2% and 70.8~135.3%, respectively. A total of 378 samples (grains, nuts, soybean and fermented soybean foods, pepper and fermented pepper foods) were purchased from the six major cities in Korea and analyzed by ELISA-LC/MS/MS system. Twenty two (5.8%; peanut: 11, pistachio: 2, walnut: 6, almond: 1, pepper powder: 1, pepper paste: 1) out of 378 samples were screened as aflatoxin B1 positive by ELISA, but, 4 (1.1%; peanut: 2, pistachio:1, pepper powder: 1) out of the 22 samples screened were confirmed as aflatoxins positive at levels of 1.02~52.79 ng/g by LC/MS/MS. ELISA-LC/MS/MS system provides a more rapid, accurate and cost-effective method for the detection of aflatoxins in large number of samples.

• 한국인쇄학회지
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• 제27권1호
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• pp.29-47
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• 2009

Generally, if RGB image is sent to the printer when we print a digital photograph, the printer will convert RGB to CMYK by the inner built-in drive. Because the difference between color domain of RGB and CMYK will cause that change and difference. The most common way to solve the problem is to convert colors by using ICC profile at RIP software or to adapt automatic color converting from the software of the original printer. So we intended to study show which way is most efficient to the digital output and which color mode device is the best based on the printer's own drive in this paper. we tried to observe and check the extended range of color space such as AdobeRGB as well as CMYK and sRGB. Then we made sure which is the suitable color space. Besides, When we convert RGB mode into CMYK mode by utilizing RIP software and adapt the printer's ICC profile made by our selves, we evaluated the output we get and compared the result with extended RGB image. The results are as follows. In case of RGB mode, the printer requests RGB, and that makes the color space more efficient than CMYK's. Converted to CMYK by utilizing RIP software, the chroma is more linearized than the one produced with its' own driver. Compared with sRGB mode's color gamut, AdobeRGB mode's color gamut and CMYK mode's color, CMYK mode's color gamut is the smallest among 3 of them. CMYK mode's color gamut by utilizing RIP software can be changeable. that can be small and narrow or wide and broad. In other words, the volume of color gamut depends on how CMYK is linearized. The color space of sRGB is more advantageous than the one of AdobeRGB in color-reproduction printed. But in the group $-b^*$, the chroma leaves behind in terms of reproduction, In the group of $-a^*$, the chroma is excellent relatively. Visual evaluation of the image, AdobeRGB image has not many reproduction colors. Specially, according to printers' characteristics, Group B of AdobeRGB and sRGB color space is a long way behind In terms of reproduction but Group Y is excellent relatively.