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Leuconostoc mesenteroides Sikhae의 Crude Dextransucrase 반응시간에 따른 Dextran 생성액의 유변성
박춘상,이철호 한국산업미생물학회 1992 한국미생물·생명공학회지 Vol.20 No.3
가자미 식해에서 분리한 Leuconostoc mesenteroides(Sikhae)로부터 생산한 dextransucrase 조효소액에 10% sucrose를 반응시켜 얻은 dextran 생성액의 유변성과 생성된 dextran의 분자량 분포 및 수율을 반응시간별로 조사하였다. Dextran 생성속도는 반응액의 HPLC를 이용한 당분석과 점도측정으로 추정이 가능하였다. Periodate oxidation 시험결과 정제된 dextran은 89%의 α-(1→6) 결합외에 11%의 α-(1→3) 부결합이 존재하는 것으로 판단되며, 반응시간이 경과함에 따라 dextran 생성액은 높은 항복력을 갖는 Bingham-pseudoplastic 유체특성을 나타내었다. 반응시간이 경과함에 따라 시간의존 특성(thixothropicity)이 증가하였는데 이러한 현상은 GPC 분석을 통하여 dextran 생성액내 고분자 dextran의 비율증가에 의한 것임을 알 수 있었다. Dextran 생성액은 반응 8시간 후에 최고점도(2680cP, γ˙=33.75s^-1, 25℃)를 나타내었으며, 그 이후부터 점도는 다시 감소하였다. 또한 dextran 생성액은 온도가 증가함에 따라 점도가 감소하였으며, 이는 Arrhenius의 일반식으로 표시할 수 있었다. Arrhenius 식으로 구한 dextran 생성액의 유동 활성화에너지는 반응시간이 경과함에 따라 증가하였으며, 8시간 반응시킨 dextran 생성액의 경우 1.69㎉/gmole 정도로써 온도증가에 의한 점도변화가 비교적 적음을 알 수 있었다. Studies on the changes in rheological properties, molecular weight distribution and dextran yield after being reacted in 10%(w/w) sucrose concentration were performed with crude dextransucrase produced from Leuconostoc mesenteroides isolated from Sikhae. The reaction rate of dextran formation was monitored by sugar analysis with HPLC and by the changes in apparent viscosity. According to the periodate oxidation test, the dextran produced in this experiment was estimated to have 89% α-(1→6) main linkages and 11% α-(1→3) side linkages. The rheological properties of the dextran solution formed changed with reaction time, and it was related to the changes in molecular weight distribution of dextran as determined by GPC analysis. As the reaction proceeded, the rheological behavior changed from Newtonian to non-Newtonian, showing Binghampseudoplastic and thixothropic flow behavior. The apparent viscosity of dextran formed solution increased with increasing reaction time, reached a maximum value of 2680 cP (γ˙=33.75s^-1, 25℃) by enzyme reaction for 8 hours, and then decreased. The temperature dependency of dextran formed solutions was well expressed by the Arrhenius equation and the activation energy reached a maximum value of 1.69 kcal/mole by enzyme reaction for 8 hours.
Reduction of the Temporal Bright-Image Sticking in AC-PDP Modules Using the Vacuum Sealing Method
박춘상,조병권,태흥식 한국정보디스플레이학회 2008 Journal of information display Vol.9 No.4
This paper investigates the effects of the existing sealing methods, such as the conventional atmospheric-pressure sealing method and vacuum sealing, on temporal bright-image sticking. To produce a residual image caused by temporal bright-image sticking, the entire region of a 42-in panel with an Xe-(11%)-He(35%) gas mixture was abruptly changed to a full-white background image after displaying a square-type image at peak luminance for about 60s. From the monitoring of the difference in the display luminance, infrared emission, color temperature, and disappearing time between the cells with and without temporal bright-image sticking, it was observed that the vacuum sealing method contributes to the reduction of temporal bright-image sticking.
Reduction of Temporal Image Sticking in AC Plasma Display Panels through the Use of High He Contents
박춘상,태흥식,Sun Ho Kim,김재현 한국정보디스플레이학회 2009 Journal of information display Vol.10 No.4
The temporal dark- and bright-image sticking phenomena were examined relative to the He contents under 11% Xe content in the 50-in HD and FHD AC-PDPs with a ternary gas mixture (Xe-He-Ne). To compare the temporal dark- and bright-image sticking phenomena under various He contents, the differences in the disappearing time, display luminance, perceived luminance, infrared emission, color coordinate, color temperature, and discharge current before and after discharge were measured under 0, 35, 50, and 70% He contents. It was found that temporal dark- and bright-image sticking were reduced in proportion to the increase in He %. Thus, a high He content contributes to the reduction of temporal dark- and bright-image sticking.