• 센서학회지
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• 제6권5호
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• pp.362-368
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• 1997

질소레이저, optode 및 광증배관을 사용하여 우라늄 농도를 원격 실시간으로 측정할 수 있는 방법을 연구하였다. 원격 측정에서 보다 효과적으로 우라늄 형광을 집광할 수 있는 optode를 설계하였으며, optode를 이용하여 우라늄 이온으로부터 나온 형광을 광섬유로 전송하여 광증배관으로 검출하였다. 신호처리에서는 온도 변화와 quencher들의 방해효과가 거의 없는 형광의 초기치를 유도하여 사용하므로 보다 정확한 우라늄 농도를 측정할 수 있었다. 측정 결과 우라늄 농도 변화에 따른 형광 강도의 변화를 쉽게 감지할 수 있었으며, 검출한계는 0.06ppm을 얻었고, $0.1{\sim}2ppm$ 범위에서 직선성이 우수하였다.

• 대한화학회지
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• 제55권6호
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• pp.932-935
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• 2011

Using tetrabutyl titanate as precursor, $Eu^{3+}$ doped $TiO_2$ nano-powder was prepared by sol-gel method, the nature of luminescence of nano-powder was studied. The interaction of chlorpyrifos with $Eu^{3+}$ doped $TiO_2$ was studied by absorption and fluorescence spectroscopy. The results indicated the fluorescence intensity of $Eu^{3+}$ doped $TiO_2$ was quenched by chlorpyrifos and the quenching rate constant ($k_q$) was $1.24{\times}10^{11}\;L/mol{\cdot}s$ according to the Stern-Volmer equation. The dynamics of photoinduced electron transfer from chlorpyrifos to conduction band of $TiO_2$ nanoparticle was observed and the mechanism of electron transfer had been confirmed by the calculation of free energy change (${\Delta}G_{et}$) by applying Rehm-Weller equation as well as energy level diagram. A new rapid method for detection of chlorpyrifos was established according to the fluorescence intensity of $Eu^{3+}$ doped $TiO_2$ was proportional to chlorpyrifos concentration. The range of detection was $5.0{\times}10^{-10}-2.5{\times}10^{-7}mol/L$ and the election limit ($3{\sigma}$) was $3.2{\times}10^{-11}$ mol/L.

• 한국식품과학회지
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• 제13권2호
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• pp.114-120
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• 1981

색소(色素)를 흡착(吸着)시킨 여지(濾紙)를 시료(試料)로 간섭(干涉)필터를 통한 자다선(紫多線)을 조사(照射)한 경우에 $45^{\circ}$ 반사각(反射角)에서 발광(發光) 및 소광(消光)의 세기를 측정하여 신속하고 간편하게 색소(色素)를 감별(鑑別)할 수 있는 방법(方法)을 시도(試圖)하였다. 발광(發光) 스펙트럼 보다는 흡수(吸收) 스펙트럼이 보다 특징적인 패턴을 나타냈다. 흡수대(吸收帶)의 파장영역(波長領域), 분포상태(分布狀態) 및 개수(個數)와 소광(消光)정도를 조사하므로써 착색료(着色料) 종류가 용이하게 판별되었다.

• Journal of Plant Biotechnology
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• 제37권4호
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• pp.567-573
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• 2010

To ascertain the effect of over-expressed maize calreticulin in tomato plant on tobamovirus movement in addition to validating potentiality of the gene (ZmCRT) as a means for the virus-resistance resource, four ZmCRT-expressing homozygous lines were generated from the T0 plants as using an Agrobacterium-mediated transformation, nucleic acid analyses, and a conventional breeding method. Of them, a line was subjected to the bioassay for tolerances to tobacco mosaic virus-U1 (TMV-U1) and tomato mosaic virus (ToMV) followed by RT-PCR and a chlorophyll fluorescence quenching analyses. Both transgenic plants transcribing ZmCRT and wild-type plants showed no symptom by 20 days after viruses inoculation, however the photosystem II quantum yield parameter measured from the upper leaves of ToMV-inoculated plants revealed that ZmCRT transgenic plants have higher photosynthetic ability than wild-type ones at that time, which indirectly implies that over-expressed ZmCRT product acts as a barrier to the cell-to-cell and/or systemic movement of ToMV. Moreover, ZmCRT transgenic plants showed remarkably longer shoot length than wild-type ones in 40 days after TMV-U1 or ToMV inoculation each, which might be resulted from higher photosynthetic ability during the phase not yet showing any external symptoms. Collectively, over-expressed ZmCRT protein in tomato plants is able to interrupt the systemic movement of infected TMV-U1 and ToMV even though not perfect.

• Bulletin of the Korean Chemical Society
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• 제33권5호
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• pp.1608-1612
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• 2012

Singlet oxygen ($^1O_2$) is an important species for oxidation in biological processes. $^1O_2$ is implicated in the genotoxic effect, and plays an important role in the cell-signaling cascade and in the induction of gene expression. However, the rapid detection of $^1O_2$ in biological environments with sufficient specificity and sensitivity is hampered by its extremely low emission probability. Here, a layer-by-layer (LbL) film of CdTe quantum dots (QDs), polymers, and ascorbate have been designed as a rapid, highly selective, and sensitive fluorescence probe for $^1O_2$ detection. Upon reaction with $^1O_2$, the probe exhibits a strong photoluminescence (PL) response even at trace levels. This remarkable PL change should enable the probe to be used for $^1O_2$ detection in many chemical and biological systems and as an environmental sensor.

• 대한화학회지
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• 제54권1호
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• pp.13-22
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• 2010

7 diethylaminocoumarin (DEAC) 레이저 염료의 광물리적 특성들을 다양한 용매에서 측정하였다. DEAC의 방출 스펙트럼은 양이온성(CTAC) 미셀과 음이온성(SDS) 미셀에서 측정하였고, 레이저 파라미터는 아세톤, 다이옥산, 에탄올 및 dimethylforamide (DMF)과 같은 여러 가지 용매에 대하여 계산하였다. DEAC의 광반응성은 366 nm 빛을 사용하여 $CCl_4$ 용매에서 연구하였고, 광화학 수득률 (${\Phi}_c$)과 속도 상수(k)도 결정하였다. picric acid (PA), tetracyanoethylene (TCNE), 7,7,8,8-tetracynoquinonedimethane (TCNQ)등의 유기 수용체와 DEAC의 상호 작용에 대한 연구는 acetonitrile ($CH_3CN$) 용액에서 형광을 측정하므로 써 수행하였다. DEAC의 전기화학적 연구는 백금 전극을 사용하여 0.1 mol/L tetrabutyl ammonium perchlorate (TBAP)/$CH_3CN$ 용액에서 순환 전류-전압법, convolutive voltammetry 및 디지털 시뮬레이션을 조합하여 수행하였고, 전기화학 파라미터도 결정하였다.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2008년도 하계학술대회 논문집 Vol.9
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• pp.335-335
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• 2008

눈에 안정한(1.53um) 인산염 레이저 유리를 제조하기 위한 기본 조성 (mole%)은 $55P_2O_5\cdot24BaO\cdot10K_2O\cdot4Al_2O_3\cdot6Yb_2O_3$로 하고, 활성 이온은 $Er^{+3}$로, sensitizer로는 $Cr^{+3}(Yb^{+3})$을 사용하였다. 혼합된 원료 조성은 대기와 원료로부터 혼입되는 OH group을 제거하기 위하여 open 시스템에서 가스 버블을 공급하였으며, 용융물에 공급된 시간 변화에 따라 분광학적 특성 변화를 조사하였다. OH oscillations linear 에 의해 quenching된 $Er^{+3}$ 형광방출 확률은 $3500cm^{-1}$ 에서 OH stretching vibration band의 흡수계수에 의존하고 있으며, 이때 $Er^{+3}$의 농도는 $1.6\times10^{19}$에서 $21.2\times10^{19}$ ion/$cm^2$ 범위에서 존재하였다.

• 한국지하수토양환경학회지:지하수토양환경
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• 제9권3호
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• pp.12-19
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• 2004

정제된 Aldrich 휴믹산(PAHA)과 한외 여과된 다양한 크기의 PAHA 성분들(PAHA UF fractions)을 이용하여 여러 고리 방향족 탄화수소(PAH)와의 결합 메커니즘을 조사하였다. 유기탄소 결합계수($K_oc$)는 전통적인 Stern-Volmer 형광 소광법과 변형 형광 소광법 두 가지를 이용하여 구하였다. 구해진 Pyrene $K_oc$ 값은 PAHA 농도와 자유 용존 pyrene 농도에 의존하였다. 이러한 비선형 흡착결합 양상은 두 물질간의 흡착성 고유상호작용이 존재한다는 것을 암시하였다. 상대적으로 분자크기가 작은 naphthalene은 중간 크기의 PAHA UF fractions과의 결합에서 높은 $KK_oc$ 값을 보여준 반면 분자 크기의 큰 PAH,즉 pyrene의 경우에는 PAHA UF fractions 크기가 크면 클수록 더 결합이 잘 되었다. 이러한 두 PAH 물질간의 불일치한 크기별 결합양상은 현재까지 제시된 고유 결합 메커니즘들 중의 하나 인 크기별 배제(size exclusion) 효과로 잘 설명되었다. 다양한 pH 조건하에서의 PAH $K_oc$ 실험에서는 일반적으로 pH가 낮아질수록 휴믹산의 산성작용기가 중화되고 그에 따라 휴믹산내의 소수성 영역이 커짐으로 인해 pyrene과 휴믹산과의 결합정도는 커졌다. 그러나 큰 사이즈의 PAHA UF fraction(>100K Da)을 사용한 실험에서는 낮은 pH가 아닌 특정 pH 범위에서 또 하나의 높은 pyrene $KK_oc$ 값을 보여줌으로서 크기별 배제 효과가 존재함을 뚜렷이 보여주었다. 이러한 크기별 배제 효과는 휴믹산의 홀(hole)구조가 PAH 크기에 적합하게 구성되어 있는 조건(휴믹성분 크기 혹은 pH)에서만 작용하는 것으로 보인다.

• 한국자동차공학회논문집
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• 제12권4호
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• pp.1-11
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• 2004

Combustion and fuel distribution characteristics of heavy duty engine with the liquid phase LPG injection(LPLI) were studied in a single cylinder engine, Swirl ratio were varied between 1.2, 2.3, and 3.4 following Ricardo swirl number(Rs) definition, Rs=2.3 showed the best results with lower cycle-by-cycle variation and shorter burning duration in the lean region while strong swirl(Rs=3.4) made these worse for combustion enhancement. Excessive swirl resulted in reverse effects due to high heat transfer and initial flame kernel quenching. Fuel injection timings were categorized with open valve injection(OVI) and closed valve injection(CVI). Open valve injection showed shorter combustion duration and extended lean limit. The formation of rich mixture in the spark plug vicinity was achieved by open valve injection. With higher swirl strength(Rs=3.4) and open valve injection, the cloud of fuel followed the flow direction and the radial air/fuel mixing was limited by strong swirl flow. It was expected that axial stratification was maintained with open-valve injection if the radial component of the swirling motion was stronger than the axial components. The axial fuel stratification and concentration were sensitive to fuel injection timing in case of Rs=3.4 while those were relatively independent of the injection timing in case of Rs=2.3.

• Nuclear Engineering and Technology
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• 제53권6호
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• pp.2025-2037
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• 2021

The influence of lead cations on natural quartz (QZ) from Egypt as a glass shielding material for the composition with nominal formula (10Na₂O - (90 - x) QZ - xPbO (where x = 30, 35, 40, 45 and 50 mol %)) was examined. The studied samples are synthesized via the melt quenching method at 1050 ℃. The X-ray diffraction XRD patterns were confirmed the glass nature for studied samples. Moreover, the optical properties, and the transparency for all compositions were examined by UV-Vis spectroscopy. Also, the major elemental composition of the natural quartz were estimated via the X-ray fluorescence (XRF) technique. Further, the density and molar volume were determined. Furthermore, the nuclear shielding parameters such as, mass attenuation coefficient, effective atomic number, electronic density, the total atomic, and electronic cross sections as well as the mean free path, and the half value layer with different gamma ray energies (81 keV-1407 keV) were calculated. Besides, the results showed that the shielding behavior towards the gamma ray radiation for all glass samples was increased as the increment in PbO concentration in the glass system.