• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.25 no.4
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• pp.81-96
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• 2020

Berthlot's reaction spectrophotometric method is generally used for the analysis of dissolved ammonium in seawater, but in recent years, a fluorescence method using an orthophthaldialdehyde-sulfite (OPA) fluorescent reagent is actively used internationally. In this study, we investigated the effects of the detection limit between the analysis methods, the reagent refractive index inherent in the spectrophotometric method, and the use of different calibration curves to understand the cause of the difference in dissolved ammonium concentration (about 0.31 𝜇M) observed in the seawater samples and a nutrient reference material between two institutions (KIOST (spectrophotometric method, one-order linear regression gradient only), Australia CSIRO (fluorescence method, quadratic formula)) conducted onboard the Australian R/V Investigator in 2017. The method detection limit (0.063 𝜇M) and the reagent refractive index background value (0.054 𝜇M) of the spectrophotometric method measured in this study could explain the difference in dissolved ammonium concentration values of the two institutes about 20% and 17%, respectively. However, when the concentration of the calibration curve of the spectrophotometric method was calculated using the same quadratic as the fluorescence method or the slope and intercept of linear regression, the difference in the dissolved ammonium concentration between the two institutions was reduced to less than the detection limit of the spectrophotometric method. Therefore, the difference in the concentration of dissolved ammonium between the two institutions, found in the nutrient reference materials and the seawater field sample during the international onboard nutrient inter-comparison experiment, may be attributed to be the effect of the different calibration curves used in the two methods rather than the effect of the difference in two analytical methods. When comparing the dissolved ammonium data from seawater samples in the future, it is recommended to pay attention to the information on the baseline, number of standard solutions, and calibration curve used in the analysis.

• The Journal of Engineering Geology
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• v.27 no.1
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• pp.67-79
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• 2017

Evaluation of the weathering index using the quantitative element composition of rocks is very effective in predicting the degree of weathering of rocks and the secondary weathering residuals. While the process of weathering varies according to the types of rocks, the study of weathering in Korea is concentrated on acidic igneous rocks. This study calculated the weathering indices using whole rock analysis (X-ray fluorescence analysis) of sandstone, mudstone, and shale belonging to clastic sedimentary rocks. The statistical significance of the indices was examined based on the correlation of the calculated weathering indices. Clastic sedimentary rocks showed higher significance of Wp, CIA, CIW and PIA weathering index indicating weathering of feldspar. Chemical Index of alteration (CIA) has the advantage of predicting weathering pathway and clay mineral production, but it is effective to consider chemical index of weathering index (CIW) simultaneously to improve accuracy. In order to reduce uncertainties due to carbonate rocks and to estimate the accurate weathering index, rock samples with high CaO content should be excluded from the evaluation of weathering index.

• Journal of Nutrition and Health
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• v.33 no.3
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• pp.250-256
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• 2000

Hyperhomocysteinemia has been shown to be associated with increased risks for macrovascular angiopathy. The present study was conducted to document the relationship between plasma homocysteine levels and the presence of macrovascular angiopath in patients with Type II diabetes mellitus. Plasma total homocysteine was determined by a HPLC-fluorescence detection method in a total of 238 subjects, 127 diabetic patients and 111 control. Dietary information including folate intake was assessed by a 24-hour recall in a total 113 subjects, 70 diabetic patients and 43 control. Folate intake was significantly lower inn patients with diabetes mellitus than that in the control. The lowered folate intake in the diabetic patients was mainly due to reduced intakes of fruits and vegetables. The average plasma homocysteine level of patients with MA was 14.2$\mu$㏖/L, which was significantly higher than that of either the patients without MA(11.4$\mu$㏖/L) or the control(11.5$\mu$㏖/L). Twenty five percent of the diabetic patients were positively correlated with age (r=0.20), body weight (r=0.28), body mass index (r=0.28), body mass index (r=0.18), diastolic blood pressure (r=0.20), and total cholesterol (r=0.14). cigarette smokers had significantly higher levels of plasma homocysteine than the non-smokers. Further prospective studies are needed to investigate whether folate or other B vitamin supplementation could be beneficial for the prevention of hyperhomocysteinemia or macrovascular angiopathy in the diabetic patients.

• Journal of Information Display
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• v.11 no.3
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• pp.123-127
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• 2010

Fluorescent white organic light-emitting diodes showing high color-rendering indices (CRIs) of up to 81 was demonstrated, with a silicon-cored anthracene derivative (PATSPA) doped with DPAVBi utilized as the deep-blue host and dye materials, and the commercial dyes rubrene and DCM2 utilized as the orange- and red-light-emitting dyes. The devices, consisting of three emissive layers, showed bright-white-light emission, but the ratio of the blue peak to the orange and red peaks changed with the current density and the thickness of the blue emissive layer. A high CRI was achieved with the use of a deep-blue emitter doped in a novel host and by optimizing the blue-layer thickness. The device with a blue-layer thickness of 10 nm showed the Commission Internationale de l'Eclairage (CIE) color coordinate of (0.33, 0.35), a high CRI of 81, and a moderate external quantum efficiency of 2% at a current density of $2.5\;mA/cm^2$.

• Journal of Biomedical Engineering Research
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• v.28 no.2
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• pp.195-198
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• 2007

In this paper, we introduce a digital cross-polarization and fluorescent color imaging system for quantitative evaluation of skin lesions. We describe the characterization of the imaging systems and the quantitative image analysis methods to show the feasibility for quantitative evaluation of skin lesions. The polarization color image was used to compute erythema and melanin index image which are useful for quantitative evaluation of pigmentation and vascular skin lesions, respectively. The fluorescent color image was used to quantitatively evaluate "sebum" and "vitiligo". In quantitative evaluation of various skin lesions, we confirmed the clinical efficacy of the imaging systems for dermatological applications. Finally, we sure that the imaging systems can be utilized as important assistant tools for the evaluation of skin lesions by providing reproducible quantitative result for widely distributed skin lesions.

• Proceedings of the Korea Association of Crystal Growth Conference
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• 1998.09a
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• pp.9-13
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• 1998

Large vacuum Bridgman-Stockbarger (BS) equipments was composed for growing large diameter CaF2 crystals. The CaF2 crystal of 4.5-inch was grown under the conditions of freezing temperature gradient of 12$^{\circ}C$/cm and growing rate of 3mm/hr. Also the 6-inch crystal was grown by using thermal stabilization method under freezing temperature gradient of 14$^{\circ}C$/cm and growing rate of 2mm/hr. The dislocation density was characterized for evaluating the quality of crystals. And the optical properties such as transmittance, refractive index and fluorescence were analyzed in order to investigate on the applications of optical components.

• Bulletin of the Korean Chemical Society
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• v.34 no.1
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• pp.128-132
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• 2013

L-Arginine semi-oxalate (LASO) single crystal has been grown by solution growth technique at room temperature. The crystal structure and lattice parameters were determined for the grown crystal by single crystal X-ray diffraction studies. Photoluminescence studies confirm the violet fluorescence emission peak at 395 nm. Optical constants like band gap, refractive index, reflectance, extinction coefficient and electric susceptibility were determined from UV-VIS-NIR spectrum. The dielectric constant, dielectric loss and ac conductivity of the compound were calculated at different temperatures and frequencies to analyze the electrical properties. The solid state parameters such as plasma energy, Penn gap, Fermi energy and polarizability were calculated to analyze second harmonic generation (SHG). Nonlinear optical property was discussed to confirm the SHG efficiency of the grown crystal.

• Transactions of the Society of Information Storage Systems
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• v.11 no.2
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• pp.22-25
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• 2015

In this paper, we demonstrate solid-immersion lens based confocal microscopy using super-continuum generation effect. Using super-continuum generation effect, we could diversify the excitation wavelength of confocal microscopy. Further, high refractive index of solid-immersion lens would increase the resolution of confocal microscopy. As a result, by applying the super-continuum generation effect and solid-immersion lens to confocal microscopy, some problems of confocal fluorescent microscopy, the excitation wavelength and the resolution, could be overcome. To verify it, we made home-built solid-immersion lens based confocal microscopy using super-continuum generation effect, and evaluate the performance of the system.

• Journal of the Korean Geographical Society
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• v.50 no.5
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• pp.505-514
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• 2015

This study analyzes a correlation between water content values and chemical index of alteration (CIA) for coarse sedimentary rocks of Mt. Cheonsaeng in Gumi-si, Kyeongsangbuk-do. Through measurement of various water values of 20 samples including water content rate, water absorption rate and equipment measuring we comparatively analyzed the values with CIA of the samples obtained by X-ray fluorescence. As a result of analysis water content rate and water absorption rate in a sedimentary rock are likely to be higher when matrix is psephitic and less compact. Furthermore the higher water content rate is, the higher CIA is due to increase of $SiO_2$ and $Al_2O_3$ and decrease of CaO and $Na_2O$ derived by chemical weathering of felspar. This correlation between water content rate and CIA represents a similar result with previous studies targeting granite.

• Proceedings of the Korean Society of Crop Science Conference
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• 2017.06a
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• pp.341-341
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• 2017

Abiotic stress adversely affects crop growth worldwide. Drought of the major abiotic stresses have the most significant impact on all of the crop. The main objective of this study was to assess the effects of drought stress on photochemical performance and vitality of maize (Zea mays L.). The photochemical characteristics were analyzed in the context of period of drought stress during the maize growth. Drought experiment was carried out for four weeks, thereafter, the drought treated maize was re-watered. The polyphasic OJIP fluorescence transient was used to evaluate the behavior of photosystem II (PSII) and photosystem I (PSI) during the entire experiment period. In drought stress, the performance Index (PI) level was reached earlier when compared to the controls. For the screening of drought stress tolerance the drought factor index (DFI) of each variety was calculated as follow DFI= log(A) + 2log(B). All the fourteen cultivars show DFI ranged from -0.69 to 0.30, meaning less useful in selection of drought tolerant cultivars. PI and electron transport flux values of fourteen cultivars were to indicate reduction of photosynthetic performance during the early vegetative stage under drought stress. In conclusion, DFI and energy flux parameters can be used as photochemical and physiological index.