• Korean Journal of Microbiology
• /
• v.40 no.1
• /
• pp.60-64
• /
• 2004

We tested gentamicin - resistant bacteria isolated from hospital sewage to confirm the presence of aac(3)II encoding aminoglycoside- (3)-N- acetyltransferase by dot-blot hybridization. A probe from the internal fragment of aac(3)II was hybridized to DNA from 41 % (39/95) of gentamicin resistant isolates. PCR was performed with primers from aac(3)II and Tn3. Of 39 strains, 13 strains had Tn3-aac(3)II structure. Minimal inhibitory concentration (MIC) test demonstrated that 18 strains containing Tn3-aac(3)II showed higher resistance to gentamicin than those of other strains. Thirteen strains were identified as 5 Escherichia coli, 3 Acinetobacter johnsonii, 2 Enterobacter agglomerans, 2 Micrococcus luteus, and 1 Pseudomonas facilis. These results suggest that gentamicin-resistant determinant of Tn3-aac(3)II structure was widely distributed in the gentamicin-resistant bacteria.

• Proceedings of the Korea Water Resources Association Conference
• /
• 2023.05a
• /
• pp.154-154
• /
• 2023

수질모니터링은 수자원 보존과 공중 보건에 있어 매우 중요하다. 기후변화로 인한 이상강우와 산업화 등의 이유로 비점오염물질 및 오염원 배출량이 증가하여 하천과 호소에 영양염류가 증가하게 된다. 영얌염류의 증가로 하천에 부영양화 상태가 지속된다면 녹조발생 등으로 인해 생태계에 부정적 영향을 초래하게 된다. 또한 부영양화는 원수의 유기물량 증가로 인해 처리비용 증가, 이취미 문제 등 인간에게도 직접적인 문제를 유발한다. 특히 우리나라의 경우 하천 취수율이 높은 국가이며, 낙동강 중상류 지역에는 산업시설이 과도하게 밀집되어 있어 하천에 오염물질 유입이 되어 부영양화가 된다면 심각한 문제를 유발하게 된다. TN은 부영양화의 중요한 지표다. 우리나라의 TN 측정은 시료 채수 후 실험실에서 수질오염공정 시험기준에 따라 진행이 된다. 실험실 분석은 TN 농도를 분석하는 일반적인 방법이며, 정확한 검출 및 정량화를 목표로 한다. 하지만 이러한 방식은 정교한 장비를 갖춘 전문 실험실 및 전문 인력을 필요로 한다. 환경부에서 주요 하천에 수질측정망을 설치하여 수질현황에 대한 종합적인 조사를 통해 수질변화 추세를 파악하는 것이 가능하지만, 실시간 TN 농도를 감지하는데 매우 제한적이다. 현재 조사방식은 TN 농도 증가로 인한 문제에 대해 초기대응을 하기에는 한계가 있다. 최근 센서의 발전으로 다양한 항목을 신속하고 지속적으로 모니터링 할 수 있게 되었다. TN에 대한 직접적인 센서 모니터링은 불가능 하지만 여러 측정 항목이 TN과 상관관계가 있는 것이 여러 연구에서 입증되었다. 이러한 결과를 바탕으로 본 연구에서는 오염도가 높은 낙동강을 대상으로 TN 예측에 대한 기초 연구를 진행하였다. 과거 측정된 자료를 활용하여 센서로 측정 가능한 항목을 통해 TN 예측을 진행하며, 실제 활용을 위해 회귀식을 도출하고자 한다. 최근 환경부에서 실시간 수질 현황 및 오염도를 파악하기 위해 자동측정망 지점을 늘리는 추세인데, 본 연구의 결과를 활용한다면 실시간 TN 예측에 대한 기초자료 활용될 수 있을 것으로 판단된다.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 1997.04a
• /
• pp.27-30
• /
• 1997

We investigated the electro-optical characteristics of amorphous (a) - twisted nematic (TN) - liquid crystal display (LCD) on polyimide (Pl) films with different polarity. It was found that the threshold voltage of a-TN-LCD is decreased with increasing the polarity of the Pl film. We considered that the threshold voltage in a-TN-LCD is affected to the surface anchoring strength with polarity of the Pl films. Also, we observed the response time of a-TN-LCD on medium polarity of the Pl film is fast compared to high polarity of the Pl film. Finally, we obtained that the viewing angle of a-TN-LCD are almost same on different polarity of the PI films.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.15 no.8
• /
• pp.726-730
• /
• 2002

Electro-optical (EO) performances of the ion beam (IB) aligned twisted-nematic (TN)-liquid crystal display (LCD) with ion beam exposure on the new diamond-like carbon (DLC) thin film surface were investigated. A good voltage-transmittance (V-T) curve of the ion beam aligned TN-LCD with oblique ion beam exposure on the DLC thin film surface for 1 min was observed. Also, the fast response time of the ion beam aligned TN-LCD with oblique ion beam exposure on the DLC thin film surface for 1 min can be achieved. Finally, the residual DC voltage of the ion beam aligned TN-LCD on the DLC thin film surface is almost the same as that of the rubbing aligned TN-LCD on a polyimide (Pl) surface.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2005.11a
• /
• pp.287-288
• /
• 2005

In this study, we have investigated electro-optical characteristics of thermal and UV stressed TN cells on the rubbed polyimide surface. Mono-domain alignments of thermal stressed TN cells over temperature of liquid crystal isotropic phase were almost same that of no thermal stressed TN cells. Also, threshold voltage and response time of thermal stressed TN cells were same that of no thermal stressed TN cells. Finally, the residual DC voltage of the thermal stressed TN cell on the polyimide surface show decrease of characteristics as increasing thermal stress time. Therefore, thermal stability of TN cell was decreased by high thermal stress for the long times.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2002.11a
• /
• pp.514-517
• /
• 2002

We investigated response characteristics of twisted nematic (TN) cell with different nematic liquid crystals (NLCs) and cell gap d on a rubbed polyimide (PI) surface. High transmittance and fast response time of the TN cell on the rubbed PI surface were achieved by using high birefringence (${\Delta}n$) and low cell gap d. The response time of TN cell on the rubbed PI surface was measured 5.1 ms. The transmittance and response time of the TN cell on the rubbed PI surface decreased with decreasing ${\Delta}nd$.

• Proceedings of the KIEE Conference
• /
• 1997.07d
• /
• pp.1579-1581
• /
• 1997

We investigated the effect of polarity of polyimide(PI) film in amorphous (a) - twisted nematic (TN) - liquid crystal display(LCD) for response time and viewing angle. We found that the domain size of a-TN-LCD on PI film with high polarity is smaller then medium polarity. It is considered that the electro-optical characteristics are strongly dependent on this domain in a-TN-LCD. We observed the response time of a-TN-LCD on PI film with high polarity is slow as comparing to PI film with medium polarity. We suggest that the response time of a-TN-LCD is attributed surface effect between the LCs and the substrates.

• Proceedings of the KIEE Conference
• /
• 1997.07d
• /
• pp.1588-1590
• /
• 1997

The viewing angle characteristics of amorphous(a)-twisted nematic(TN)-liquid crystal display (LCD) on poly(vinyl)cinnamate (PVC) surfaces with photo polymerrization were investigated. It was found that the threshold voltage increases with increasing the polymerization of PVC surfaces. That the domain size of a-TN-LCD is affected by the surface crystallization with increasing the photo polymerization of the photo-alignment film. We observed that the viewing angle of a-TN-LCD increased with increasing the photo polymerization on PVC surfaces. Finally, we consider that the viewing angle of a-TN-LCD on PVC surfaces is large compared to a-TN-LCD on polyimide(PI) surface.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.15 no.9
• /
• pp.808-811
• /
• 2002

We investigated response characteristics of twisted nematic (TN) cell with different nematic liquid crystals (NLCs) and cell gap d on a rubbed polyimide (PI) surface. High transmittance and fast response time of the TN cell on the rubbed PI surface were achieved by using high birefringence (Δn) and low cell gap d. The response time of TN cell on the rubbed PI surface was measured 5.1 ms. The transmittance and response time of the TN cell on the rubbed PI surface decreased with decreasing Δnd.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 1998.06a
• /
• pp.109-112
• /
• 1998

In this paper, we studied on electro-optical (EO) characteristics of photo-aligned twisted nematic (TN)-LCD. We obtained that uniform LC alignment in TN-LCD with linearly polarized ultraviolet (LPUV) light irradiation on polyimide (PI) surface increases according to increasing irradiation time for 10 to 60 min. The voltage-transmittance and response time characteristics of photo-aligned TN-LCD with UV light irradiation time of 60 min were almost same in comparison with conventional TN-LCD were observed. From the results, we suggest that photo-aligned TN-LCD with LPUV light irradiation on PI surface is useful in applying LCD as for rubbing-free treatment method.