• 한국세라믹학회지
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• 제49권6호
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• pp.614-619
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• 2012

We investigated color and graphite layer formation on the surface of Type I tinted brown diamonds exposed for 5 minutes under a high-pressure high-temperature (HPHT) condition in a stable graphite regime. We executed the HPHT processes of Process I, varying the temperature from $1600^{\circ}C$ to $2300^{\circ}C$ under 5.2 GPa pressure for 5 minutes, and Process II, varying the pressure from 4.2 to 5.7 GPa at $2150^{\circ}C$ for 5 minutes. Optical microscopy and micro-Raman spectroscopy were used to check the microstructure and surface layer phase evolution. For Process I, we observed a color change to vivid yellow and greenish yellow and the growth of a graphite layer as the temperature increased. For Process II, the graphite layer thickness increased as the pressure decreased. We also confirmed by 531 nm micro-Raman spectroscopy that all diamonds showed a $1440cm^{-1}$ characteristic peak, which remained even after HPHT annealing. The results implied that HPHT-treated colored diamonds can be distinguished from natural stones by checking for the existence of the $1440cm^{-1}$ peak with 531 nm micro-Raman spectroscopy.

• 한국지구과학회지
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• 제40권4호
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• pp.315-328
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• 2019

Since the Coastal Zone Color Scanner (CZCS)/Nimbus-7 was launched in 1978, a variety of studies have been conducted to retrieve ocean color variables from multi-satellites. Several algorithms and formulations have been suggested for estimating ocean color variables based on multi band data at different wavelengths. Chlorophyll-a (chl-a) concentration is one of the most important variables to understand low-level ecosystem in the ocean. To retrieve chl-a concentrations from the satellite observations, an appropriate algorithm depending on water properties is required for each satellite sensor. Most operational empirical algorithms in the global ocean have been developed based on the band-ratio approach, which has the disadvantage of being more adapted to the open ocean than to coastal areas. Alternative algorithms, including the semi-analytical approach, may complement the limits of band-ratio algorithms. As more sensors are planned by various space agencies to monitor the ocean surface, it is expected that continuous monitoring of oceanic ecosystems and environments should be conducted to contribute to the understanding of the oceanic biosphere and the impact of climate change. This study presents an overview of the past and present algorithms for the estimation of chl-a concentration based on multi-satellite data and also presents the prospects for ongoing and upcoming ocean color satellites.

• Restorative Dentistry and Endodontics
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• 제44권1호
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• pp.10.1-10.11
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• 2019

Objectives: The objective of this study was to assess coronal discoloration induced by the following intracanal medicaments: calcium hydroxide (CH), a mixture of CH paste and chlorhexidine gel (CH/CHX), and triple antibiotic paste (3Mix). Materials and Methods: Seventy extracted single-canal teeth were selected. Access cavities were prepared and each canal was instrumented with a rotary ProTaper system. The specimens were randomly assigned to CH, CH/CHX, and 3Mix paste experimental groups (n = 20 each) or a control group (n = 10). Each experimental group was randomly divided into 2 subgroups (A and B). In subgroup A, medicaments were only applied to the root canals, while in subgroup B, the root canals were completely filled with medicaments and a cotton pellet dipped in medicament was also placed in the pulp chamber. Spectrophotometric readings were obtained from the mid-buccal surface of the tooth crowns immediately after placing the medicaments (T1) and at 1 week (T2), 1 month (T3), and 3 months (T4) after filling. The ${\Delta}E$ was then calculated. Data were analyzed using 2-way analysis of variance (ANOVA), 3-way ANOVA, and the $Scheff{\acute{e}}$ post hoc test. Results: The greatest color change (${\Delta}E$) was observed at 3 months (p < 0.0001) and in 3Mix subgroup B (p = 0.0057). No significant color change occurred in the CH (p = 0.7865) or CH/CHX (p = 0.1367) groups over time, but the 3Mix group showed a significant ${\Delta}E$ (p = 0.0164). Conclusion: Intracanal medicaments may induce tooth discoloration. Use of 3Mix must be short and it must be carefully applied only to the root canals; the access cavity should be thoroughly cleaned afterwards.

• 한국표면공학회지
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• 제51권3호
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• pp.157-163
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• 2018

The anodic $TiO_2$ layers which are prepared in various anodization conditions exhibit their specific color depending on the thickness of $TiO_2$. In this study, the relationship between the color of $TiO_2$ layer, which is grown by PEO (Plasma electrolytic oxidation), and the thickness of the $TiO_2$ layer is investigated. To evaluate the color change of the $TiO_2$ layer, the value of color ($dE^*ab$) is measured and calculated by spectrophotometer and chromameter. As a result, it is found that $dE^*ab$ values and thickness of $TiO_2$ layers form a linear relationship with meaningful formular. This formula can be helpful to quantify the thickness of the $TiO_2$ layer by the numerical $dE^*ab$ values. In this process, the spectrophotometer shows more precise results than the chromameter dose. If fluoride ions ($F^-$) are included in the electrolyte, it will affect the $dE^*ab$ values of the $TiO_2$. layer. This is against the propensity, which is analyzed by XRD (X-ray diffraction) and XPS (X-ray photoelectron spectroscopy). It is important that the formular suggested in this study provides other metals which can be also anodized with the possibility of quantifying the thickness of the $TiO_2$ layer by the $dE^*ab$ values.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2000년도 춘계학술대회 논문집
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• pp.543-550
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• 2000

This study investigated and analysed the surface contaminant of the passenger car. Because the surface contaminants change the paint color of the passenger car, it is necessary to cleanse them for prolongating the maintenance period, Analysis method of the contaminant according to the kind of the passenger car, the line and the part of the train are systemized. Contamination mechanism and deterioration reason of paint colors on the surface of passenger car are studied. We expect that results of this study could contribute to providing of a fundamental research data, which is necessary for the development of a low-pollution passenger car cleanser.

• 한국의류산업학회지
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• 제21권4호
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• pp.509-514
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• 2019

Cotton fabrics were treated with gelatin to enhance dyeability and color strength when using Caesalpinia sappan dye. Gelatin was used as the protein and a pad-dry- cure method was used for the treatment process (2, 4, 6, 8, 10, 12, 14g/l concentration). Pretreated fabrics were mordanted with 10% alum. Fabrics were then dyed with freeze-dried sappan wood water extract powder form. Dyed samples were assessed in regards to dyeing behavior and color fastness. Comparing untreated and gelatin treated samples from the SEM images indicated that the Gelatin treatment (10g/l) resulted in an enhanced surface roughness that was relative to that of untreated cotton. Padding cotton with gelatin at 6g/l concentration afforded dyed fabrics with a 2 times increase in the K/S value over that of untreated fabrics. All dyed samples were red color with a significant enhancement in the sample color strength (K/S) being observed for pretreated samples. pH values favor dye absorption with pH 7 yielding the highest color strength. Dyeing at an elevated temperature resulted in a lower color strength and reddish-dull color. Longer dyeing times created greater color strengths for untreated and gelatin treated cotton. Increased dye concentrations resulted in higher K/S values for both gelatin treated and untreated cotton. As for color fastness, gelatin treated and untreated cotton fabrics dyed with sappan wood extract showed a relatively low rating in washing fastness (color change 1 rating), light fastness (1 rating), and rubbing fastness (wet:1-2, dry:3-4 rating).

• 한국포장학회지
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• 제17권1호
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• pp.13-17
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• 2011

반가공 상태의 절단마늘의 저장성을 향상시키는 적정 포장 조건을 찾기 위하여 기체 투과도가 다른 필름으로 밀착 포장하고 저장 중 품질을 비교하였다. 박피 후 2등분 절단한 마늘을 400 g 단위로 통기성 포장(대조구), $30{\mu}m$ 저밀도 폴리에틸렌(LDPE), $50{\mu}m$ 폴리올레핀 PD 900, $20{\mu}m$ 폴리올레핀 PD 941 필름으로 밀착포장하고 $1{\pm}1^{\circ}C$에서 52일 동안 저장하면서 포장 내 기체조성과 함께 마늘의 중량감소, 표면색도, 경도, 가용성 고형분 함량, 부패율을 측정하였다. 외기의 공기 조성인 통기성 포장을 제외한 밀봉 필름 포장에서는 저장 45일 후에 대체적으로 $O_2$ 농도는 1~5%로, $CO_2$ 농도는 12~21%로 형성되었다. 통기성 포장에서는 저장 45일째에 높은 곰팡이 부패 발생과 함께 급격한 중량감소가 나타났고 색택 변화도 심하였다. 모든 포장에서 저장 중, 경도는 감소하고 가용성 고형분 함량은 큰 변화가 없었다. 낮은 기체투과도로 인하여 포장 내에 낮은 $O_2$ 농도와 높은 $CO_2$ 농도를 보였던 PD 900 포장에서 짓무름 현상과 곰팡이 성장이 없이 52일 동안 저장될 수 있어서 가장 우수한 저장성을 나타내었다.

• 펄프종이기술
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• 제44권1호
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• pp.24-30
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• 2012

This study was carried out in order to analyze a repletion possibility about color change of base paper after elevated heat exposure when wooden fillers were added. Fillers may reduce production cost because its price is usually inexpensive than pulp with higher bulkiness. Wooden fillers have lower density than inorganic fillers, so they may increase bulk more than inorganic fillers. Never the less wooden fillers have disadvantage of yellow color by heat exposure, so the addition level should be carefully controlled. Brightness and whiteness changes after elevated heat exposure depending on coating weight were analyzed. With wooden fillers addition, breaking length and surface strength decreased but bulkiness increased. As the exposure time of elevated heat increased the coating paper with wooden fillers addition had higher brightness and whiteness values than those of inorganic fillers.

• 패션비즈니스
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• 제8권6호
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• pp.137-145
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• 2004

According to the experimental results, it has been reported by several researchers that the air-permeability values of the fabrics mostly decreased by the mordanting during the dyeing procedure. The exact quantitative information, however, has not been presented so far. In this study, the change of the fabric air-permeability was investigated quantitatively. At the same time, the change of the fabric air-permeability according to the dyeing procedure. In order to investigate the possibility of the detachment of the metal ions on the fiber or fabric surface, the change of the air-permeability was investigated after several rinsing of the mordanted fabrics. By comparing the color differences of the cochineal dyed fabrics which were subjected to rinsing procedure after mordanting, the effect of the rinsing of the mordanted fabrics on the dyeing of fabrics was investigated. At the range of mordant concentration, 2% Cu, 2% Sn, 2% Fe, 2% Cr, 5% Al, the metal ions are not excessively absorbed on the fiber surface. Also, any remarkable detachment of the metal ions does not accompany after the mordanting with the subsequent rinsing procedure.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2004년도 하계학술대회 논문집 Vol.5 No.2
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• pp.1104-1108
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• 2004

A Study has been made of surface modification of various polymers by ion implantation to change the optical transmittance property at ultraviolet ray (UV, $200\sim400nm$). The substrates were PC (Polycarbonate), PET(Polyethyleneteraphtalate) and PP (Polypropylene). The effects of ion implantation on the change of optical transmittance were investigated in relation to ion species, implantation energies and ion fluences. The N, Ar, Kr, Xe ion implantation performed at ion energies from 20 to 50keV. The fluences ranged from $5\times10^{15}$ to $7\times10^{16}ions/cm^2$. UV/Vis transmittance spectroscopy, FT-IR and XPS were used to investigate optical transmittance, chemical structure and surface chemical state of irradiated polymer. Surface color was changed from the yellow to the dark brown and the transmittance of UV ray in the range UV-A($320\sim400nm$) decreased more than 80% after ion implantation.