• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2019.05a
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• pp.278-280
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• 2019

Flow cytometer is one of the instrument that can measure various optical properties of a single cell or microparticle. These parameters including size, granularity, and fluorescence intensity are determined by the physical and optical interaction of the cells with excitation light source. However, users have some difficulties such as high cost, size of instrument, and limited fluorescence selectivity. In addition, abundant data is also unintentionally acquired even though user wants to have a single optical parameter. For these reasons, the use of flow cytometer is more challenging for researchers to apply their study. Therefore, the proposed study aims to develop a low-cost portable fluorescence acquisition system using a commercially available light-emitting diode and photodiode. It is designed by a 3D printer, and fluorescence selectivities are increased by changing of the light source / optical filter / detection sensor. Various number sets of fluorescently labeled cells were measured, and its feasibility was evaluated through the proposed system. As a result, acquried fluorescence intensities were proportional to the concentration of the cells and showed high linearity.

• Journal of Korean Society of Environmental Engineers
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• v.28 no.6
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• pp.667-676
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• 2006

The reduction of $Hg^{2+}$ in the aqueous phase results in the production of dissolved gaseous mercury(DGM), and the volatilization of DGM has been identified as an important mechanism for the loss of Hg from waterbodies to the atmosphere. Although mercury emission in the world is known to be mostly from Asia, there have been few studies of measuring DGM concentrations in lakes in Asia. In this study, DGM concentrations were measured at Juam reservoir($35^{\cir}00'N,\;127^{\circ}14'E$), Korea. The results showed that the average concentrations of DGM at the upper and down stream of the lake during summer time were $95{\pm}8\;and\;130{\pm}15$ pg/L, respectively and the concentration of total mercury(TM) at the upper and down stream was $2.1{\pm}0.7,\;1.7{\pm}0.3$ ng/L respectively. Average DGM concentration during summer time($101{\pm}14pg/L$) was approximately 5.5 times higher than that during fall($18{\pm}0.1pg/L$). The DGM concentrations ai the midstream decreased from 32 to 13.7 pg/L during rain event, while the TM concentrations increased from 2.2 ng/L to 2.7 ng/L indicating the deposition of mercury from the atmosphere. Also, the diurnal patterns between DGM concentrations and UV intensities were observed. Water temperatures and DOC concentrations were significantly related to DGM concentrations, while TM concentrations were negatively related to DGM concentrations(p<0.0001). Comparing with the study of Dill et al.,(2006) the average concentrations of DGM $(109{\pm}15pg/L)\;and\;TM(2.2{\pm} 0.4ng/L)$ at Juam reservoir were approximately 3 and 2.2 times higher than those measured in other lakes(DGM: $38{\pm}16pg/L$, TM: $1.0{\pm}1.2ng/L$).

• Journal of Dental Rehabilitation and Applied Science
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• v.25 no.4
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• pp.437-444
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• 2009

The purpose of this study was to evaluate the physical properties of different automixing resin cements and the shear bond strength on dentin. For this study, two self-adhesive automixing resin cement(Rely-X Unicem(3M ESPE, St. Paul, USA), Embrace resin cement(Pulpdent, Oakland, USA)) and one chemical polymerizing resin cement(Resiment Ready-Mix(J.L.Blosser Inc., Liberty Missouri, USA)) were used. To evaluate the physical properties, compressive strength, diametral tensile strength and flexural strength were measured. The specimens were fabricated using Teflon mould according to manufacturers' instructions and stored for 24 hours in an atmosphere of 100% humidity. To evaluate the shear bond strength on dentin, each cements were adhered to buccal dentinal surface of extracted human lower molars in 2mm diameter. Physical properties and shear bond strengths were measured using universal testing machine(Z010, Zwick GmbH, Ulm, Germany) at a crosshead speed of 0.5mm/min. The physical properties and shear bond strength of different automixing resin cements were statistically analyzed and compared between groups using One-way ANOVA test and Schffe post-hoc test at the 95% level of confidence. The result shows that chemical polymerizing automixing resin cement represents the relatively higher physical properties and shear bond strength than self-adhesive automixing resin cements.

• Korean Journal of Poultry Science
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• v.37 no.4
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• pp.383-388
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• 2010

The chicken eye can discriminate light color, and different light wavelengths may affect reproduction ability. This study was carried out to identify effect of monochromatic light using light emitting diode (LED) in laying hens. Chickens were exposed to white light (WL), blue light (BL), yellow light (YL), green light (GL) and red light (RL) made by using LED as well as incandescent light (IL) (control). All light sources were equalized to a light intensity of 20 lux. The results indicated that the age of first egg laying and 50 % egg laying in laying hens treated under RL is significantly younger than under other lights (P<0.05). And the ovary weight of laying hens reared under RL is significantly heavier than under other at from 16 to 20 wks (P<0.05). The largest number of eggs production was produced in a group with treated with RL by 59 wks of age compared with any other group. The egg weight of YL was greater than other treatment groups from 26 to 45 wks (P<0.05). The egg shell from hens treated with RL was the strongest and thickest at 20 wk (P<0.05). These results suggest that the egg quality of laying hens reared in different spectrum of LED can be different and RL may enhance the laying performance.

• Investigative Magnetic Resonance Imaging
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• v.2 no.1
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• pp.83-88
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• 1998

Purpose : Authors correlated the three-dimensional time-of-flight MRA signal intensity characteristics and flow profile simulated by computer in an experimental flow phantom model. Materials and Methods : The three-dimensional time-of-flight MRA was performed in a fusiform flow phantom and analyzed the flow signal. computer assisted flow simulation was performed in same flow geometry. The MRA signal intensity and flow velocity distribution and direction was compared. Results : The flow was depicted as homogeneous signal internsity in inlet and outlet area and inhomogeneous signal intensity in fusiform area. Typically, the flow was depicted as target appearance in transition area to outlet. Whereas mean signal internsity decreased slowly in fusiform area, it rapidly dropped and resumed in transition area to outlet. In computer assisted flow simulation, Whereas there were flow velocity decrease and flow direction change to peripheral in entrance to fusiform area, ther were rapid flow velocity resuming and flow direction change to central in transition area to outlet. Conclusion : The signal loss and target appearance in transition area to outlet is characteristic of fusiform flow. These signal changes correlate with abrupt flow velocity and direction change well.

• Korean Journal of Food Science and Technology
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• v.45 no.4
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• pp.416-421
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• 2013

The purpose of this study was to investigate the effects of pH, temperature, light, sugars, and organic acids on the stability of anthocyanin pigments extracted from aronia (Aroniamelanocarpa). Pigments from aronia were most stable at pH 3.0, with maximal absorbance at 514 nm. High temperatures and prolonged heating substantially reduced anthocyanin contents. Anthocyanin levels were as low as approximately 21.70 and 79.63% of normal levels after 300 min of heating at 30 and $100^{\circ}C$, respectively. All of the sugars tested decreased the abundance of aronia pigments, with the levels highest in the presence of maltose, and decreasing progressively in the presence of galactose, sucrose, glucose, and fructose. Among the organic acids tested, citric acid was the most effective in stabilizing the aronia pigment, followed by tartaric acid, malic acid, formic acid, and ascorbic acid. These results provide useful reference data for efforts to use pigments from aronia in processed foods or for developing natural food colorants.

• Korean Journal of Optics and Photonics
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• v.23 no.2
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• pp.77-86
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• 2012

The connection between the continuousness of Rabi oscillation and the discontinuity of quantum jumps has long remained one of the conceptual difficulties since the discovery of the quantum physical paradigm. In this study, however, we demonstrate that the behavior of the atom-field composite system gradually changes from the continuous Rabi interaction to the discontinuous quantum jumps as the atom-field coupling strength is reduced. The reduction occurs through enlarging the quantization volume of the mode so that the mode approaches one of the infinitely many modes of the thermal background.

• Applied Chemistry for Engineering
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• v.8 no.4
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• pp.637-639
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• 1997

Samples of $YTa_7O_{19}$ doped with $Tm^{3+}$ were prepared using the solid state reaction method to investigate their photoluminescence characteristics. The samples were identified by XRD and SEM, and the optical measurement was also carried out. Under 359 nm excitation, $YTa_7O_{19}$ doped with $Tm^{3+}$ exhibited a narrow-band blue emission, at about 455 nm. The maximum emission intensity was obtained at $YTa_7O_{19}$ doped with 0.12 mole $Tm^{3+}$. This revealed the concentration quenching of emission intensity.

• Journal of the Korean Ceramic Society
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• v.36 no.3
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• pp.319-324
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• 1999

기존의 고상 반응법에 의해 합성된 YNbO4 : Bi 형광체의 발광특성을 개선하기 위하여 B2O3 융체 첨가법으로 형광체를 합성하고, 빛발광(PL) 및 저전압 음극선발광(CL)을 측정하였다. PL 및 CL 모두 415~440 nm 영역에서 강한 청색 발광 스펙트럼을 나타냈으며, 고상 반응의 경우와 마찬가지로 Y/Nb 비율이 화학 양론상의 1:1인 경우보다 결함구조를 인위적으로 조절한 51/49나 54/46에서 최대의 발광강도를 보였다. 한편, 고상 반응에서는 125$0^{\circ}C$에서 4시간 열처리하는 것이 최대의 발광효과를 나타냈으나, B2O3융제를 첨가하고 110$0^{\circ}C$에서 열처리한 시료가 결정성이 좋고 입자의 크기 및 형태가 균일하여 PL뿐만 아니라 CL에서도 우수한 발광특성을 보였다. B2O3융제를 첨가하는 방법으로 열처리 온도를 낮추고 입자크기와 형태를 조절하여 형광체의 휘도를 개선할 수 있었다.

• Proceedings of the Korean Vacuum Society Conference
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• 2016.02a
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• pp.220-220
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• 2016

본 연구에서는 녹황색 빛을 내는 NaY(WO4)2:Tb3+ 형광체 파우더를 하소 350도에 1시간 소결 950도에 4시간 고상반응법으로 합성하였으며, 파우더는 X-ray diffraction과 PL 장비를 이용하여 측정하였다. XRD 분석은 Tb3+이온 도핑농도에 의한 순수한 NaYWO4 상을 나타내었다. Fig.1 220-330nm에서 관찰되는 넓은 밴드는 $O2-{\rightarrow}W6+$에 의해 발생한 LMCT(ligand to metal charge transfer)이고, Tb3+에서 WO42-그룹으로 에너지 전달에 의해서 생긴다. 이것의 최대세기는 272nm 이다. LMCT 옆 330-390nm에 관찰되어지는 약한 강도와 넓은 밴드는 Tb3+ 4f8의 f-f transition에 의해 발생한다. Fig.2에서 보여 지듯이$ 5D4{\rightarrow}7F6$, 7F5, 7F4, 7F3는 파장 489nm, main peak인 545nm (Green,초록색), 588nm (orange, 주황색), 620nm (Red, 적색)에서 Peak가 나타났으며, Tb3+이온의 함량비가 0.08mol일 때 최대 발광이 관측 되었다.