• 생약학회지
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• 제33권4호통권131호
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• pp.312-318
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• 2002

Effect of the acid hydrolysate of silk fibroin on obesity was investigated in obese(057BL/KsJ-db/db) mice. After 8 weeks feeding of 1%(w/w) or 3%(w/w) fibroin hydrolysate, the extents of reduction in body weight were significantly higher than that of obese control. The weight reduction in female mice was higher than that in male mice. Plasma leptin in male mice increased up to 1.8-fold higher level than obese control by feeding hydrolysate. In case of female mice, however, it rather decreased with increased feeding concentration of hydrolysate. From the results of high glycine and serine contents of peptide fractions contained in fibroin hydrolysate, it was inferred that fibroin peptides might affect xylosyltransferase(XT) activity on chondroitin sulfate synthesis causing to change susceptibility of adipocytes to hormones such as insulin followed by the reduced leptin synthesis in female mice. The result of the higher lipolysis in hydrolysate-fed group than obese control indicated that the reduction in body weight was due to the increased lipolytic activities in male and female mice in common.

• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 2008년도 International Symposium on Remote Sensing
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• pp.22-25
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• 2008

Aperture synthesis with platform motion has been presented as a useful tool to achieve the high spatial resolution imaging. Using a motion induced synthetic aperture radiometer (MISAR), a passive microwave image can be achieved with a small number of antennas. Moreover, the MISAR is capable of imaging better than the case without motion, using the same configuration of antenna array. With a platform motion, visibility can be sampled more efficiently, and as a result the imaging performance of the MISAR shows higher quality than the case without platform motion. In this paper, the advantage of MISAR is demonstrated experimentally. Using a laboratory model of inteferometric radiometer, the point source images are obtained under the condition with platform motion and without platform motion. In the experimental results, the point source response of the MISAR shows better quality of sidelobe level and beam efficiency than the case without platform motion.

• 한국음향학회지
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• 제20권6호
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• pp.82-86
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• 2001

본 논문에서는 평행한 이중 선 배열을 위한 합성 기법을 제안하고자 한다. 일반적으로 천해에서 사용되는 단일 배열은 신호의 이득을 높이고 각 분해능을 높이기 위해서 긴 어퍼쳐 길이를 요구하고 있다. 그러나 원거리로부터 발생한 극 저주파 신호는 수신단에서 어레이를 기준으로 좌, 우 모호성을 드러낸다. 이러한 문제점을 해결하기 위해 평행한 이중 선 배열을 이용하면서 합성 기법을 적용하였다. 어레이 합성 기법은 연속적인 시간에서 얻어진 각각의 데이터들을 빔 영역에서 코히어런트한 합성을 거쳐 공간 영역에서 가상의 어레이로 확장하였다. 제안된 방법은 인접한 다중 음원 환경에서의 각도 오차를 줄이고 어레이 합성 횟수에 따라 향상된 분해능성능을 나타내었다. 시뮬레이션 결과 어레이 합성 기법을 적용하기 전과 5회의 합성을 수행했을 경우, 평균 부엽 레벨은 약 7dB가 향상되었다.

• Nuclear Engineering and Technology
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• 제53권5호
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• pp.1593-1601
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• 2021

Oxide dispersion strengthening (ODS) tungsten alloys are highly desirable in irradiation applications. However, how to improve the properties of ODS-tungsten alloys efficiently has been worth studying for a long time. Here we report a nanostructuring approach that achieves W-La₂O₃ alloy with a high level of flexural strength and Vickers hardness at room temperature, which have the maximum value of 581 MPa and 703 Hv, respectively. This method named solution combustion synthesis (SCS) can generate 30 nm coating structures W-La₂O₃ composite powders by using Keggin-type structural polyoxometalates as raw materials in a fast and low-cost process. The composite powder can be fabricated to W-La₂O₃ alloy with an optimal microstructure of submicrometric W grains coexisting with nanometric oxide particles in the grain interior, and a stability interface structure of grain boundaries (GBs) by forming transition zones. The method can be used to prepare new ODS alloys with excellent properties in the future.

• Journal of Nutrition and Health
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• 제31권9호
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• pp.1394-1403
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• 1998

The study was designed to observe the effect of dietary calcium and fats on plasma cholesterol level, hepatic microsomal fluidity and HMG-CoA reductase activity as well as the excretion of fecal bile acids and neutral sterols in 1, 2-dimethylhydrazine(DMH)-treated rats. Male Sprague Dawley rats, at 7 weeks of age, were divided into 2 groups, 0.3% and 1.0% Ca levels and each group again subdivided into 2 groups of corn oil and perilla oil. Each rat was intramuscularly infused with DMH for 6 weeks to give total dose of 180mg/kg body weight and also fed experimental diet containing 15%(w/w) different fit and Ca(0.3% or 1.0%) for 20 weeks. High dietary calcium(1.0%) did not significantly influence on plasma cholesterol as well as hepatic microsomal fluidity and HMG CoA reductase activity, but significantly reduced the excretion of total bile acid per gram of faces and increased the excretion of total neutral sterol. However, high dietary Ca reduced the excretion of secondary bile acid(deoxycholic and lithocholic acids) which was known as promoter for colon cancer. Perilla oil rich in n-3 ${\alpha}$-linolenic acid significantly decreased plasma cholesterol by increasing hepatic microsomal fluidity compared with corn oil, but did not influence on HMG CoA reductase activity. Perilla oil did not influence on fecal excretion of total and primary bile acids, but reduced the excretion of secondary bile acids. Therefore, it could be recommended to consume more fish product and food rich in calcium and use more perilla oil in meal preparation to prevent from coronary hear disease and colon cancer especially when high fit diet has been practiced. (Korean Nutrition 31(9) : 1394-1403, 1998)

• Journal of Microbiology and Biotechnology
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• 제19권3호
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• pp.299-306
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• 2009

Dissolved oxygen (DO) has a significant effect on the molecular weight of hyaluronic acid (HA) during the fermentation of Streptococcus zooepidemicus. Therefore, to further investigate the effect of DO on the yield and molecular weight of HA, this study compared the metabolic flux distribution of S. zooepidemicus under aerobic conditions at various DO levels. The metabolic flux analysis demonstrated that the HA synthesis pathway, considered a dependent network, was little affected by the DO level. In contrast, the fluxes of lactate and acetate were greatly influenced, and more ATP was generated concomitant with acetate at a high DO level. Furthermore, the has gene expression and HA synthase activity were both repressed under anaerobic conditions, yet not obviously affected under aerobic conditions at various DO levels. Therefore, it was concluded that the HA molecular weight would seem to depend on the concomitant effect of the generation of ATP and reactive oxygen species. It is expected that this work will contribute to a better understanding of the effect of the DO level on the mechanism of the elongation of HA chains.

• Journal of Microbiology and Biotechnology
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• 제12권5호
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• pp.813-818
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• 2002

Expression of monokine induced by IFN-$\gamma$(Mig) mRNA is well-known to strictly depend on Interferon-$\gamma$(IFN-$\gamma$). Lipopolysaccharide (LPS) alone Is weakly effective on Mig mRNA expression in mouse Peritoneal macrophages. This study was undertaken to investigate the synergistic effect of LPS and IFN-$\beta$ on chemokine Mig gene expression in mouse peritoneal macrophages. Although IFN-$\beta$ alone was minimally effective, LPS plus IFN-$\beta$ synergized to produce a high level of Mig mRNh. The synergistic effect of LPS and IFN-$\beta$ (LPS/IFN-$\beta$) on Mig mRNA expression was strain-specific. The most effective synergistic effect of LPS/IFN-$\beta$ on the mRNh expression was found in simultaneous stimulation of LPS/IFN-$\beta$. This synergy was modulated at the level of the gene transcription and was not dependent on a new protein synthesis. Synergistic effect of LPS/IFN-$\beta$ also required the activation of $NF-_KB$. Accordingly, these data suggest that LPS/IFN-$\beta$ synergizes the expression of Mig mRNA through a process that depends on a pretranscriptional level and/or coincident Mig mRNA transcription.

• Journal of Microbiology and Biotechnology
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• 제23권4호
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• pp.451-458
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• 2013

The human gastric pathogen Helicobacter pylori (Hp) has been considered a microaerophile. However, we recently reported that, when supplied with 10% $CO_2$, Hp growth is stimulated by an atmospheric level of $O_2$, suggesting that Hp is a capnophilic aerobe. In this study, we investigated the effects of aerobic $O_2$ tension on Hp cells by comparing gene expression profiles of cultures grown under microaerobic and aerobic conditions in the presence of 10% $CO_2$. The results showed that overall differences in gene expression in Hp cells grown under the two $O_2$ conditions were predominantly growth-phase-dependent. At 6 h, numerous genes were down-regulated under the aerobic condition, accounting for our previous observation that Hp growth was retarded under this condition. At 36 h, however, diverse groups of genes involved in energy metabolism, cellular processes, transport, and cell envelope synthesis were highly up- or down-regulated under the aerobic condition, indicating a progression of the cultures from the log phase to the stationary phase. The expression of several oxidative stress-associated genes including tagD, katA, and rocF was induced in response to aerobic $O_2$ level, whereas trxA, trxB, and ahpC remained unchanged. Altogether, these data demonstrate that aerobic $O_2$ tension is not detrimental to Hp cells but stimulates Hp growth, supporting our previous finding that Hp may be an aerobic bacterium that requires a high $CO_2$ level for its growth.

• 농약과학회지
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• 제2권1호
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• pp.24-31
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• 1998

천연물기원 신농약 개발을 위해 유용 식물자원 탐색 및 활성물질의 분리, 동정 결과 벼멸구 살충활성이 높고 분자구조상 유기합성이 용이한 것으로 판단되는 피마자잎중 활성물질 ricinine의 유도체 합성을 통해 고활성 화합물을 얻고자 하였다. 합성된 ricinine을 선도물질로 하여 활성을 증진하고자 분자구조 유사화합물을 비롯한 카바메이트계, 유기인계 화합물 12종을 합성하였다. 카바메이트계 유도체 합성시 전구물질의 pyridine 구조중 carbo기가 있는 chlororicinic acid, ricinic acid는 공명구조가 파괴되어 methyl isocyanate와 반응이 이루어지지 않았다. 유기인계 유도체의 경우 P에 O와 S가 결합된 oxon과 thiono형의 유도체를 합성한 결과 합성수율은 oxon형이 65% 이상인 반면에 thiono형은 20% 미만으로서 낮은 수율을 보였다. 합성 유도체의 생리활성 평가에 있어 유기인계 유도체는 oxon형보다 thiono형 화합물이 높은 살충효과를 나타냈다. Thiono형 유도체는 500 ${\mu}g/ml$ 수준에서 벼멸구에 대한 살충력이 모두 100%이었으며 점박이응애의 경우 특이적으로 thiono형 유도체중 alkyl기의 부분이 methyl인 경우 높은 활성을 나타냈다. Oxon형 유도체, 분자구조 유사화합물과 카바메이트계 유도체의 경우에는 살충력이 나타나지 않았다. 살균 활성은 pyridine ring의 2번 위치에 $NH_{2}$기가 있는 유도체의 경우 200 ${\mu}g/ml$ 수준의 실내검정에서 10종 병원균에 대해 $85{\sim}100%$의 생장저지효과를 보여주었으며, 온실검정에서도 250 ${\mu}g/ml$ 수준에서 벼도열병과 보리흰가루병에 대해 각각 92%, 86%의 방제효과를 나타냈다.

• Journal of Microbiology and Biotechnology
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• 제9권2호
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• pp.140-146
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• 1999

When methanol was the sole carbon source, Methylobacterium organophilum NCIB 11278, a facultative methylotroph, accumulated Poly-$\beta$-hydroxybutyrate (PHB) as 59% (w/w) of dry cell weight under potassium limitation, 37% under sulfate limitation, and 33% under nitrogen limitation. Based on a stoichiometric analysis of PHB synthesis from methanol, it was suspected that PHB synthesis is accompanied by the overproduction of energy, either 6-10 ATP and 1 $FADH_2$ or 6 ATP and 3 NADPH to balance the NADH requirement, per PHB monomer. This was confirmed by observation of increased intracellular ATP levels during PHB accumulation. The intracellular ATP with limited potassium, sulfate, and ammonium increased to 0.185, 0.452, and 0.390 $\mu$moles ATP/g Xr (residual cell mass) during PHB accumulation, respectively. The intracellular ATP level under potassium limitation was similar to that when there was no nutrient limitation and no PHB accumulation, 0.152- 0.186 $\mu$moles ATP/g Xr. We propose that the maximum PHB accumulation observed when potassium was limited is a result of the energy balance during PHB accumulation. Microorganisms have high energy requirements under potassium limitation. Enhanced PHB accumulation, in ammonium and sulfate limited conditions with the addition of 2,4-dinitrophenol, which dissipates surplus energy, proves this assumption. With the addition of 1 mM of 2,4-dinitrophenol, the PHB content increased from 32.4% to 58.5% of dry cell weight when nitrogen limited and from 15.1 % to 31.0% of dry cell weight when sulfate limited.