• International Journal of Aeronautical and Space Sciences
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• 제14권4호
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• pp.398-407
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• 2013

Optical tomography was used to measure the pattern of spray cross-section. The maximum-likelihood estimation (MLE) algorithm was used to reconstruct the spray cross-section from the measured transmission rate of the spray. A swirl-type injector was used to form an optically dense spray, and the test was carried out in a high-pressure chamber, to control the pressure condition of the test site. Before the experiment, the reliability of the MLE-based reconstruction algorithm was verified, by comparing it with a conventional filtered back projection reconstruction (FBP) method. The MLE algorithm showed superior reconstruction of the image. In the spray patternation experiment, the results of the optical tomography and optical line patternator, which uses Mie scattering signal information, were compared. While measuring the cross-section of optically dense spray, the intensity of the scattering signal had attenuated to an uncorrectable level, which led to incorrect spray pattern measurement by the optical line patternator. However, reliable results were obtained by optical tomography, under the same condition. Finally, the pattern of the optically dense spray was measured at various chamber pressures, of up to 3 MPa. As the chamber pressure increased, the hollow cone-shaped swirl spray shrank, and the attenuation coefficient value of the inner region increased.

• 대한치과보철학회지
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• 제34권4호
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• pp.816-822
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• 1996

The purpose of this study was to determine whether there was any difference in the mean porosity of denture base resin cured by microwave energy, when the liquid monomers of denture resin(K-33 : methyl methacrylate for conventional water bath curing or Acron MC : special monomer for microwave curing) and/or the thicknesses of denture base($5{\times}10{\times}60mm\;or\;10{\times}10{\times}60mm$) were varied. The mean porosities of k-33 specimens cured in water bath with two different thicknesses were used as control. The results were as follows : 1. Regardless of specimen thickness, Acron MC cured by microwave energy showed the least mean porosity, followed by K-33 cured by water bath heat, and K-33 cured by microwave energy showed the highest level of mean porosity(P<0.05). 2. In both K-33 and Acron MC cured by microwave energy the mean porosities of 5mm thickness groups were lower than those of 10mm thickness groups(P<0.05). But no significant difference was found in mean porosity between 5mm thickness and 10mm thickness of water bath heat cured groups made of K-33(P>0.05).

• Journal of Magnetics
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• 제21권1호
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• pp.141-147
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• 2016

Staphylococcus aureus cultures exposed to rotating magnetic field (RMF) were studied in order to analyse the possible induced changes in staphylococcal enterotoxin genes (se) expression. Liquid cultures of S. aureus strains carrying different se were exposed to the RMF of magnetic frequency 50 Hz and magnetic induction 34 mT for 10 h at $37^{\circ}C$. Three time points of bacterial growth cycle were considered for RNA extractions. Gene expression analyses were evaluated using real-time quantitative PCR method. The present study confirmed, that the RMF can stimulate the growth rate of S. aureus cultures in comparison to the unexposed controls, while the stimulation is not strain dependent. The studies have also shown, that the RMF, depending on the exposure time but regardless the bacterial strain, can influence on the expression of various se. In general, except for sea, as a result of bacterial exposure to the RMF through subsequent growth phases, the expression of se decreased, reaching the values below results recorded for unexposed controls. In the case of sea expression remained at a lower level as compared to the control, regardless the time of exposition.

• 대한의생명과학회지
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• 제16권2호
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• pp.96-104
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• 2010

In this study, the effects of HP4060, a pomegranate extract, on Sprague-Dawley (SD) female rats were investigated. SD rats used in the experiment were divided into 3 groups: a control group, 100 mg HP4060/kg rat powder fed group, and 25 mg HP4060/kg rat liquid fed group. After 20 days of administration, the changes of the brain neurotransmitters were measured. The data showed that the concentration of the serotonin and the norepinephrine were increased, whereas that of the epinephrine was decreased in HP4060 administered groups. In addition, the improving effect of HP4060 on depression symptom of menopause women were shown by increased immobility time of the SD rates in a separate experiment. The uterus weight of HP4060 fed groups were also shown to be increased. In order to monitor toxic effect of HP4060, glutamic-oxaloacetic transaminase (GOT) and glutamic-pyruvic transaminase (GPT) levels were measured, and the results showed that no significant difference in GOT and GPT levels among experimental groups implying no significant toxic side effects of HP4060. According to these results, it seems clear that HP4060 may improve symptoms of hot flush and depression caused by menopause without significant level of toxic effects.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2013년도 제45회 하계 정기학술대회 초록집
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• pp.256-256
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• 2013

Carbon nanotubes (CNT) / polyvinylidene fluoride (PVDF) piezoelectric composite films for nanogenerator devices were fabricated by spray coating method. When the CNT/PVDF mixture solution passes through the spray nozzle with small diameter by the compressed nitrogen gas, electric charges are generated in the liquid by a triboelectric effect. Then randomly distributed ${\beta}$ phase PVDF film could be re-oriented by the electric field resulting from the accumulated electrical charges, and might be resulted in extremely one-directionally aligned ${\beta}$ phase PVDF film without additional electric field for poling. X-ray diffraction patterns were used to investigate crystal structure of the CNT/PVDF composite films. It was confirmed that they revealed extremely large portion of the ${\beta}$ phase PVDF crystalline in the film. Therefore we could obtain the poled CNT/PVDF piezoelectric composite films by the spray coating method without additional poling process. Charge accumulation and resulting electric field generation mechanism by spray coating method were shown in Fig. 1. The capacitance of the CNT/PVDF films increased by adding CNTs into the PVDF matrix, and finally saturated. However, the I-V curves didn't show any saturation effect in the CNT concentration range of 0~4 wt%. Therefore we can control the performance of the devices fabricated from the CNT/PVDF composite film by adjusting the current level resulted from the CNT concentration with the uniform capacitance value.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2008년도 제31회 추계학술대회논문집
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• pp.125-128
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• 2008

30톤급 액체산소-케로신 액체로켓엔진 개발의 중간 단계로서 연소기를 제외한 터보펌프 등의 엔진 주요 구성품을 이용한 터보펌프+가스발생기 개회로 연계시험이 수행되었다. 터보펌프+가스발생기 개회로 연계시험의 시험기 구성 및 시험결과를 제시하였다. 연소기를 오리피스로 모사하는 상태에서의 터보펌프+가스발생기 개회로 연계시험기의 예냉, 시동기를 이용한 시동 및 가스발생기 점화, 터보펌프 정격 구동이 성공적으로 수행되었다. 개회로 연계시험 결과는 터보펌프+가스발생기 폐회로 연계시험 수행을 위해 활용되었다.

• Animal Bioscience
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• 제35권8호
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• pp.1195-1204
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• 2022

Objective: The objective of this study was to investigate the in vitro fermentation profiles of different soybean oligosaccharides (SBOs) and their effects on skatole production and cecal microbiota of broilers. Methods: Five SBOs with varying main component contents were fermented using an in vitro batch incubation inoculated with broiler cecal microbiota. Gas production was recorded automatically, skatole, indole and short-chain fatty acids (SCFAs) were determined using high-performance liquid chromatography, and microbial changes were analyzed using 16S DNA gene sequencing. Results: The addition of SBOs increased (p<0.05) gas production, suggesting bacterial growth-stimulating activities. In addition, the concentrations of indole were significantly (p<0.05) decreased after SBO supplementation, and SBO III, with higher sucrose and stachyose contents, decreased (p<0.05) the skatole level. Our results also revealed that the fermentation of SBOs by cecal microbiota produced (p<0.05) SCFAs, which were dominated by propionic acid, butyrate acid and lactic acid compared to the control. In addition, SBO III increased (p<0.05) the abundance of Firmicutes and Subdoligranulum and decreased that of Bacteroides. Conclusion: These results suggest that SBOs with higher sucrose and stachyose contents are promising prebiotics in modulating gut microbiota and reducing odor emission in broilers.

• 한국미생물·생명공학회지
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• 제44권2호
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• pp.150-155
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• 2016

본 연구에서는 고등어 필렛에 침지액 및 초정수압을 처리하여 침지액과 초정수압의 압력에 따른 고등어 필렛의 품질 특성 변화를 알아보기 위해 생균수, pH, 물성, 색차 및 관능 평가를 실시하였다. 생균수를 측정한 결과, 침지액 처리를 하였을 때 무처리구보다 균수가 감소하였고 침지액 및 초정수압을 병행 처리하였을 때 압력이 높아질수록 2 log cycle 정도 균수가 감소하여 생육이 억제됨을 확인하였다. pH 측정 결과, 초정수압 처리에 의해 압력이 증가할수록 단백질의 구조가 변하면서 pH가 약간 증가하는 경향을 나타내었다. 물성의 경우 압력이 증가할수록 경도, 검성 및 씹힘성이 증가하였으며 다른 항목들에서는 유의적인 큰 차이가 없는 것으로 나타났다. 색도의 경우 초정수압 처리 시 단백질의 변성으로 압력이 증가할수록 명도와 백색도가 증가하였다. 관능평가 결과, 초정수압 처리 시 압력이 높아질수록 경도와 탄력성이 증가함을 보였다. 따라서 본 연구 결과, 고등어 필렛에 침지액 및 초정수압을 병행 처리하였을 때 미생물의 효과적인 증식 억제로 고등어의 선도 저하 방지 및 품질 개선에 효과적일 것으로 사료된다.

• Weed & Turfgrass Science
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• 제7권1호
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• pp.62-71
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• 2018

본 연구는 부식산 함유 액비(LFH)의 시비에 따른 크리핑 벤트그래스의 생육과 품질의 변화를 확인하기 위해 잔디의 가시적 품질, 엽록소 함량, 예지물량, T/R ratio, 양분 함량 및 흡수량을 조사하였다. 처리구는 대조구(CF), LFH 1,000배 처리구(HF-1), LFH 500배 처리구(HF-2) 및 LFH 250배 처리구(HF-3)로 구분되었다. LFH 처리 전후에 토양화학성은 차이를 나타내지 않았다. LFH처리구와 대조구를 비교하였을 때, 가시적 품질과 뿌리 생육량은 LFH처리구에서 증가하였고, 엽록소 함량, 잔디 예지물, 질소 흡수량은 HF-2처리구와 HF-3처리구에서 각각 11.2-11.8%, 15.3-30.8%, 22-42%씩 증가하였다. LFH처리량에 따라 가시적 품질, 엽록소 함량, 잔디 예지물 및 양분 흡수량은 정의 상관성을 나타내었다. 이 결과들을 종합해 볼 때, 크리핑 벤트그래스에서 부식산 함유 액비의 시비는 잔디의 잎 조직 중 잔디지하부의 생육이 증가하여 양분 흡수를 개선함으로써 잔디품질과 생육이 증가하는 것을 확인 할 수 있었다.

• Weed & Turfgrass Science
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• 제6권3호
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• pp.272-281
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• 2017

본 연구는 부식산 함유 액비(LFHA)의 시비에 따른 잔디의 생육과 품질의 변화를 평가하기 위해 수행하였다. 처리구는 대조구(CF), HA-1 ($CF+1ml\;m^{-2}LFHA$), HA-2 ($CF+2ml\;m^{-2}LFHA$), and HA-3 ($CF+4ml\;m^{-2}LFHA$)로 구분되었다. LFHA 처리 전후에 토양화학성은 차이를 나타내지 않았다. LFHA처리구와 대조구를 비교하였을 때, HA-2처리구와 HA-3처리구의 잔디 품질은 9월, 10월 및 11월 조사에서 높았고, 잔디예지물은 10월 27일 조사에서 증가하였다. 줄기 밀도, 뿌리 길이, 잎조직 내 질소, 인산 및 칼륨의 함량은 LFHA처리구에서 증가하였다. 잔디예지물은 잎 조직 내 인산 및 칼리함량이나 줄기 밀도와 정의 상관성을 보였고, 부식산 함유 액비는 잔디 밀도, 잔디예지물 및 잎조직 내 질소 및 인산함량과 각각 정의 상관성을 나타내었다. 이 결과들을 종합해 볼 때, 크리핑 벤트그래스에서 부식산 함유 액비의 시비는 잔디의 잎 조직 중 질소와 인산의 흡수가 증가하여 잔디예지물과 밀도가 증가하는 것을 확인 할 수 있었다.