Active blend films from chitosan-gallic acid (CGA) and polyvinyl alcohol (PVA) were prepared via a simple mixing and casting method through the addition of citric acid as a plasticizer. The CGA/PVA ...blend films were characterized using Fourier transform infrared spectroscopy (FT-IR). The mechanical properties including tensile strength (TS) and elongation at break (%E), degree of solubility (S) and swelling behavior (DS), water vapor adsorption, and antimicrobial activities of the CGA/PVA blend films with and without LED (light emitting diode)-UV irradiation were also investigated. The CGA/PVA blend films exposed to UV irradiation exerted a higher TS (43.5MPa) and lower %E (50.40), S (0.38) and DS (2.73) compared to the CGA/PVA blend films (TS=41.7MPa, %E=55.40, S=0.42, and DS=3.16) not exposed LED-UV irradiation, indicating that the cross-linkage between CGA and PVA had been strengthened by LED-UV irradiation. However, the water vapor adsorption in the CGA/PVA blend films increased due to the changes of surface roughness and pore volume after LED-UV irradiation, and all values increased by increasing the CGA concentrations in the CGA/PVA blend films. The antimicrobial activities of the CGA/PVA blend films showed that the efficient concentration of CGA in the CGA/PVA blend films was over 1.0%. Taken together, the CGA/PVA blend films have potential for use as food packing materials.
•The CGA/PVA blend films were prepared to be used as biodegradable packaging after UV irradiation.•The physico-chemical properties of the CGA/PVA blend films were determined.•The CGA/PVA blend films showed good antimicrobial activities.
Chitosan and its derivatives have been reported to have anti-inflammatory effects in vitro and in vivo. It is also suggested that chitosan and its derivatives could be up-regulating heme oxygenase-1 ...(HO-1) in different models. However, the up-regulation of HO-1 by chitosan oligosaccharides (COS) remains unexplored in regard to anti-inflammatory action in lipopolysaccharide (LPS)-stimulated murine macrophages (RAW264.7 cells). Treatment with COS induced HO-1 expression in LPS-stimulated RAW264.7 cells, whereas the expression of inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) was decreased. Pretreatment with ZnPP, a HO-1 inhibitor, reduced the COS-mediated anti-inflammatory action. HO-1 induction is mediated by activating the nuclear translocation of NF-E2-related factor 2 (Nrf2) using COS. Moreover, COS increased the phosphorylation of extracellular signal regulated kinase (ERK1/2), c-Jun N-terminal kinase/stress-activated protein kinase (JNK), and p38 MAPK. However, specific inhibitors of ERK, JNK, and p38 reduced COS-mediated nuclear translocation of Nrf2. Therefore, HO-1 induction also decreased in RAW264.7 cells. Collectively, COS exert an anti-inflammatory effect through Nrf2/MAPK-mediated HO-1 induction.
An active synthetic aperture sonar mounted on small UUV is generated various trajectory disturbances in the traveling path by the influence of external underwater environments. That is the phase ...mismatch occurs in the synthetic aperture processing of the signals reflected from seabed objects and fetches the detection performance decreases. In this paper, we compensated deteriorated images by the active SAS autofocus processing using DPC and analyzed the effects of detection performance when the periodic trajectory disturbances occur in the side direction at a constant velocity and straight movement of UUV. Through simulations, the deteriorated images according to the periodic disturbance magnitudes and period variations in the platform were compensated using difference phases processing of the overlapping displaced phase centers on the adjacent transmitted ping signals, and we conformed the improved performance characteristics of azimuth resolution and detection images at 3dB reference point. 소형 수중무인체에 탑재 운용되는 능동 합성개구면소나는 외부 수중환경의 영향으로 진행경로에 여러 가지 궤적 교란이 발생한다. 이는 해저 물체에서 반사된 신호의 합성 개구면처리에 있어서 위상 부정합이 발생되어 탐지성능의 저하를 가져 온다. 본 논문에서는 수중무인체가 정속도 직선기동시 현측방향으로 주기적 궤적교란이 발생될 때 DPC를 이용한 능동 SAS 자동초점처리로 훼손된 이미지를 보상하고 탐지성능에 미치는 영향을 비교 분석하였다. 시뮬레이션을 통해 플랫폼의 주기적 교란 크기 및 변동 주기에 의한 훼손된 이미지는 인접된 송신 핑신호의 겹쳐진 위상중심점 위상차 적용으로 궤적교란 보상처리가 가능하고 3dB 기준 방위해상도 및 탐지 이미지의 성능개선 특성을 확인하였다.
In the case of a small UUV operating an active synthetic aperture sonar, various velocity disturbances may occur on the path due to the influence of external underwater environment, and this causes ...phase errors in coherent synthetic aperture processing, which has a large influence on the detected image. In this paper, when a periodic sinusoidal velocity disturbance is generated in the traveling direction, the phase generated by the round trip slope range at each position is estimated the cross correlation coefficient for multiple received signals and compensated the position variation in the overlapped DPC by the average value within the maximum allowable width. Through simulations, it has been confirmed that the images degraded by the velocity disturbance amplitude and fluctuating frequency of the UUV are removed from the false targets and the performance of azimuth resolution is improved by the proposed phase compensation method. 능동 합성 개구면 소나를 운용하는 소형 수중 무인체는 외부 수중환경의 영향으로 진행경로에 여러 가지 속도 교란이 발생될 수 있으며, 이는 코히어런트 합성 개구면 처리시 위상 오차를 발생시켜 탐지 이미지에 큰 영향을 미친다. 본 연구에서는 진행방향으로 주기적 사인형태의 속도 교란이 발생될 때 각 위치에서 왕복 진행 경사거리에 의해 발생되는 위상을 다중 수신 신호에 대한 상호상관 계수를 추정한 후 중첩된 DPC에서의 위치변위를 최대 허용범위 내에서의 평균값으로 보상하는 방법을 제시하였다. 시뮬레이션을 통하여 수중 무인체의 속도 교란 크기 및 변동 주파수에 의해 손상된 이미지는 제시된 위상 보상 방법으로 허위 표적 제거 및 방위해상도의 성능이 개선됨을 확인하였다.
Active synthetic aperture sonar on the small UUV is generated several trajectory disturbances under the influences of underwater environments, and causing a large error in the synthetic aperture ...processing. In this paper, we analyzed the effects of azimuth resolution for the phase mismatch of the synthetic aperture focus processing when the periodic or random trajectory disturbances was generated on the side direction. The simulation results show that ghost targets are generated and azimuth resolution is very deteriorated when disturbance amplitude is greater than $0.3{\lambda}$ and disturbance period is greater than $2L_{sa}$ in the periodic trajectory disturbances environments. And detection performance on the seabed small objects by the synthetic aperture processing is shown that there is a significant effects on the azimuth resolution depending on the types and conditions of the platform trajectory disturbance variations. 수중에서 운용되는 소형 무인정 탑재 능동 합성개구면소나는 외부에서 발생되는 수중환경의 영향으로 플렛품 진행시 여러 가지 궤적 교란이 발생하게 되고 개구면 합성처리에 있어서 많은 오차를 가져 온다. 본 논문에서는 진행현측방향으로 주기적 및 랜덤 궤적교란이 발생될 때 합성개구면 초점처리에 의한 위상차 부정합에 따른 방위해상도에 미치는 영향을 비교 분석하였다. 시뮬레이션 결과, 주기적 궤적교란은 발생 교란 크기가 $0.3{\lambda}$, 변동 주기가 $2L_{sa}$보다 커지면 허위표적이 발생되고 방위해상도가 매우 나빠지게 되며, 합성개구면처리에 의한 해저 소형물체 탐지성능은 플렛폼의 궤적변동 종류와 조건에 따라서 방위해상도에 많은 영향을 미치는 특성을 나타내었다.
The Korean road network has been aging rapidly. It is necessary to assess the pavement conditions of various road networks in order to come up with proper rehabilitation strategies against the aging ...road networks. Pavement management system is an essential tool for road management, and each road management organization has developed its own pavement condition index for assessing the road conditions. Nonetheless, because the pavement condition of various types of roads could not be represented by a single pavement condition index, it was difficult to comprehend the condition of the entire roads of Korea and its changing trend at a glance. Moreover, there has been a limitation on the persuasion of the justification for the use of road management and rehabilitation budget at national level to the people and the budget office of Korea. This study derived the relationship among the pavement condition indices of Korean expressways, Korean national highways, and Seoul city roads so that those pavement indices can be represented by one unified pavement condition index. A sensitivity analysis of how variables of pavement distress (roughness, rut depth, and crack ratio) influenced each of the pavement condition index was carried out. Then, correlation equations between the pavement condition indices were developed in order to represent them by a single pavement condition index (NHPCI) through a statistical analysis of the pavement condition monitoring system data over 8 years, and its application plan is proposed.
The aim of this study was to identify the relationships between borderline serum liver enzyme abnormalities and the incidence of impaired fasting glucose (IFG) and diabetes mellitus (DM) during a ...7-year follow-up of workers, and to evaluate the quantitative level of risks.
A total of 749 workers in an electronics manufacturing company were divided into the normal fasting blood glucose (n = 633), IFG (n = 98), and DM (n = 18) groups, according to the results of their health checkup in 2006. Among 633 workers in the normal group, excluding 55 workers who were impossible to follow, incidence rate and relative risks of 578 workers to the IFG or DM in 2013 according to the levels of aspartate aminotransferase (AST), alanine aminotransferase (ALT), and gamma-glutamyltransferase (γ-GTP) were investigated. The liver enzyme levels were categorized as A (normal), B (borderline elevation), and R (definite elevation) following the standard of the National Health Insurance Service of Korea.
The incidence rate of IFG or DM based on ALT level was 9.7 % for the A, 30.0 % for B, and 15.4 % for R. According to γ-GTP, the incidence rate was 9.8 % for A, 34.5 % for B, and 25.0 % for R. The relative risk(RR) to the incidence of IFG or DM depending on the level of ALT were 3.09 in B and 1.59 in R compared to A. According to γ-GTP, RR was 3.52 in B and 2.55 in R compared to A. AST level was not related to the incidence of IFG or DM. A multiple logistic regression analysis with the incidence of IFG or DM as a dependent variable resulted in an odds ratio of 2.664(1.214-5.849) for B level ALT, 3.685(1.405-9.667) for B level of γ-GTP even after adjustment for other variables such as age, sex, body mass index, AUDIT score, systolic blood pressure, and triglyceride.
Even borderline elevations of ALT and γ-GTP, but not AST, increased the incidence and risk of IFG or DM after 7 years. Borderline elevation of ALT and γ-GTP was identified as an independent risk factor of IFG or DM.
This paper proposes a technique to analyze the flatness characteristics of the attenuator at 10Hz to $50\text\tiny{MHz}$ on the basis of $1\text\tiny{kHz}$ using a Thermal Voltage Converter and AC ...measurement standard. In the proposed technique, the input voltage of the attenuator for each measuring frequency is supplied at the same rate as $1\text\tiny{kHz}$ using TVC, and the flatness characteristics of the attenuator are analyzed by the voltage variation indicated in the AC measurement standard. The results of the analysis of the attenuator flatness characteristics show that the maximum uncertainty of $866{\mu}V/V$ can be measured from $10\text\tiny{dB}$ to $70\text\tiny{dB}$ and the uncertainty is reduced by about 37% compared to $2.31\text\tiny{mV}$/V using the network measurement method. The improved attenuator flatness characteristic values can be applied to the frequency flatness calibration from 2.2V to 2.2mV at the low voltage of the AC measurement standard. 본 논문은 열전압변환기와 교류측정표준을 사용하여 10Hz에서 50MHz 대역의 감쇠기 평탄도 특성을 1kHz를 기준으로 분석하는 기법을 제안하였다. 제안된 기법은 TVC를 사용하여 측정 주파수별 감쇠기의 입력전압을 1kHz와 동일하게 공급한 후, 교류측정표준에서 지시되는 전압 변화량으로 감쇠기의 평탄도 특성분석을 수행하였다. 감쇠기 평탄도 특성분석의 결과는 1dB에서 70dB까지 최대 $866{\mu}V/V$의 불확도로 측정이 가능하며, 기존 회로망 측정방법을 사용한 2.31mV/V 보다 약 37%의 불확도가 감소된 것을 확인하였다. 향상된 감쇠기 평탄도 특성 값은 교류측정표준의 저전압 2.2V에서 2.2mV까지 주파수 평탄도 교정에 적용할 수 있다.
The PME(precision measurement equipment) used in the measurement to check the performance of the equipment in military weapon system is periodically calibrated to maintain measurement reliability ...during the life cycle. Previous studies suggest that reliability models are determined by considering sample size and characteristics of equipment. However, it may not be fit well to apply a single model assuming the same characteristic distribution for the maintenance date of many kinds of PMEs. This paper proposes that the most suitable calibration interval for maintenance data is selected through the F-test and the performance index evaluation among the calibration intervals estimated from the measurement reliability models assuming the characteristic of the bath-tub curve during the life cycle of various PMEs. The research results show that the reliabilities of various types of equipment are maintained during calibration intervals. 군 무기체계의 성능을 점검하기 위해 사용되는 정밀측정장비는 수명주기 동안 측정신뢰도 유지를 위해 주기적으로 교정된다. 기존의 교정주기 관련 연구들은 장비의 샘플 크기와 특성을 고려하여 측정신뢰도 모델을 결정할 것을 제안하고 있으나, 다양한 정밀측정장비의 정비 데이터에 동일한 특성 분포를 가정하고 단일 모델을 적용하는 것은 적합하지 않을 수 있다. 본 논문에서는 정밀측정장비의 수명주기 동안 욕조 곡선의 특성을 가정하여 측정신뢰도 모델들로부터 추정된 교정주기 가운데 F-검정과 성능지수 평가를 통해 정비 데이터에 가장 적합한 교정주기가 선택되도록 제안하였다. 제안한 방법을 다양한 장비에 적용한 결과 교정주기 동안 장비의 신뢰도가 유지됨을 확인하였다.
The bimetallic Pt–Au catalysts supported on ZnO/Al2O3 with different Pt/Au molar ratios were prepared by impregnation (IMP) method using a mixed solution of Pt and Au precursor. These were ...characterized by X-ray diffraction (XRD), CO chemisorption, temperature programmed reduction (TPR), and transmission electron microscopy (TEM) equipped energy dispersive spectroscopy (EDS). Catalytic activity for complete oxidation of toluene was measured using a flow reactor under atmospheric pressure. In the results, the aggregation of Au particles depended on themolar ratio in the bimetallic Pt–Au catalyst, and Pt particles was well dispersed homogeneously even by the IMP method. The Pt75Au25 and Pt67Au33 catalysts concurrently coated with Pt and Au precursors by IMP method showed higher activity than monometallic Pt and Au catalyst for toluene oxidation. Also, in order of the catalytic activity for toluene was very good agreement compare with the TPR results. The Au particles might promote the toluene oxidation over the bimetallic catalyst concurrently coated with Pt and Au particles. Therefore, the size of Pt and Au particles and catalytic activity were confirmed to be correlated to molar ratio of Pt and Au loaded.
The bimetallic Pt–Au catalysts supported on ZnO/Al2O3 with different Pt/Au molar ratios were prepared by impregnation (IMP) method using a mixed solution of Pt and Au precursor. These were characterized by X-ray diffraction (XRD), CO chemisorption, temperature programmed reduction (TPR), and transmission electron microscopy (TEM) equipped energy dispersive spectroscopy (EDS). Catalytic activity for complete oxidation of toluene was measured using a flow reactor under atmospheric pressure. In the results, the aggregation of Au particles depended on themolar ratio in the bimetallic Pt–Au catalyst, and Pt particles was well dispersed homogeneously even by the IMP method. The Pt75Au25 and Pt67Au33 catalysts concurrently coated with Pt and Au precursors by IMP method showed higher activity than monometallic Pt and Au catalyst for toluene oxidation. Also, in order of the catalytic activity for toluene was very good agreement compare with the TPR results. The Au particles might promote the toluene oxidation over the bimetallic catalyst concurrently coated with Pt and Au particles. Therefore, the size of Pt and Au particles and catalytic activity were confirmed to be correlated to molar ratio of Pt and Au loaded. KCI Citation Count: 23
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