• 원예과학기술지
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• 제29권3호
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• pp.172-180
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• 2011

The net photosynthetic rate of 'Seolhyang' strawberry plants was measured daily for 7 days after treatment at three UV illumination dosages (0, 9.8, and 29.5 $kJ{\cdot}m^{-2}$). The net photosynthetic rates of the strawberry plants with 9.8 and 29.5 $kJ{\cdot}m^{-2}$ UV light illumination decreased by 20.2 and 61.4%, respectively, at 7 days after UV light treatments. UV treatments with two illumination dosages (7.9 and 15.7 $kJ{\cdot}m^{-2}$) altered the phenolic compounds contents during the cultivation period when compared to those in the control fruits. The anthocyanin content with 7.9 $kJ{\cdot}m^{-2}$ UV light illumination of 'Seolhyang' increased by 18.7% compared with those in control fruits at the 11 DAT. However, the anthocyanin content of 'Maehyang' was not significantly different among treatments during experiment period. The highest level of ellagic acid was found with 7.9 $kJ{\cdot}m^{-2}$ UV light illumination in both cultivars at the 11 DAT. Our results showed that strawberries illuminated with UV light during cultivation period had higher bioactive compounds contents than control fruits. These results suggest that UV light treatments may be a useful non-chemical way of promoting strawberry fruits quality.

• Journal of Biosystems Engineering
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• 제35권2호
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• pp.124-131
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• 2010

Chlorophyll fluorescence has been researched for assessing fruit post-harvest quality and condition. The objective of this preliminary research was to investigate the potential of fluorescence spectroscopy for measuring apple fruit quality. Ultraviolet (UV) and blue light was used as an excitation source for inducing fluorescence in apples. Fluorescence spectra were measured from 'Golden Delicious' (GD) and 'Red Delicious' (RD) apples using a visible/near-infrared spectrometer after one, three, and five minutes of continuous UV/blue light illumination. Standard destructive tests were performed to measure fruit firmness, skin and flesh color, soluble solids and acid content from the apples. Calibration models for each of the three illumination time periods were developed to predict fruit quality indexes. The results showed that fluorescence emission decreased steadily during the first three minutes of UV/blue light illumination and was stable within five minutes. The differences were minimal in the model prediction results based on fluorescence data at one, three or five minutes of illumination. Overall, better predictions were obtained for apple skin chroma and hue and flesh hue with values for the correlation coefficient of validation between 0.80 and 0.90 for both GD and RD. Relatively poor predictions were obtained for fruit firmness, soluble solids content, titrational acid, and flesh chroma. This research has demonstrated that fluorescence spectroscopy is potentially useful for assessing selected quality attributes of apple fruit and further research is needed to improve fluorescence measurements so that better predictions of fruit quality can be achieved.

• 한국결정성장학회지
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• 제11권5호
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• pp.231-237
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• 2001

Etch rates up to 120 nm/min for $Ta_{2}O_{5}$ were achieved in both $SF_{6}/Ar$ and $Cl_{2}/Ar$ discharges. The effect of ultraviolet (UV) light illumination during ICP etching on $Ta_{2}O_{5}$ etch rate in those plasma chemistries was examined and UV illumination was found to produce significant enhancements in $Ta_{2}O_{5}$ etch rates most likely due to photoassisted desorption of the etch products. The effects of ion flux, ion energy, and plasma composition on (Ba, Sr)$TiO_3$ etch rate were examined and maximum etch rate ~90 nm/min was achieved in $Cl_{2}/Ar$ ICP discharges while $CH_{4}/H_{2}/Ar$ chemistry produced extremely low etch rates (${\leq}10\;nm/min$) under all conditions.

• Food Science and Biotechnology
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• 제17권6호
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• pp.1345-1348
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• 2008

Titanium dioxide ($TiO_2$) shows antibacterial effects when exposed to near ultra violet (UV) light. In this study, $TiO_2$ photocatalytic continuous reactor was designed and applied to food-borne pathogens such as Vibrio parahaemolyticus ATCC 17802, Salmonella choleraesuis ATCC 14028, and Listeria monocytogenes ATCC 15313. $TiO_2$ films were prepared by conventional sol-gel dip-coating method using titanium tetra iso-propoxide (TTIP). The antibacterial activity of photocatalytic reactor with various flow rates and UV-A illumination time showed effective bactericidal activity. As the UV-A illumination time increased, survival rates of those bacteria decreased. After 60 min of UV-A illumination, the survival rates of V. parahaemolyticus and S. choleraesuis were less than 0.1%. However, that of L. monocytogenes was about 5% at that time point. These results present an effective way to exclude pathogenic bacteria from aqueous foods.

• 한국환경과학회지
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• 제9권6호
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• pp.463-468
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• 2000

Ther effect of UV on the mortality rate of toxic dinoflagellate Amphidinium Carterae causing a red tide in the coastal area of korea was investigated in the batch and continuous-scale reactor equipped with ultraviolet irradiation-apparatus. Degussa P(sub)25 titanium oxide, a photocatalyst proved to be effective of the mortality of Amphidinium Carterae supplied with photocatalyst and UV radiation were greater than 95% in 2 minutes of UV radiation and the rate were higher than that by UV-radiation without titanium dioxide in the batch and continuous-flow scale reactor, The mortality time of Amphidinium Carterae increased with the cell density under UV-illumination in the batch scale reactor. The mortality rate in the density of $5.0$\times$10^4$ cell/mL at the same experimental condition was more than 90% in 4 minutes in the continuous flow scale reactor. The percentage of 99.9$\pm$0.1% of Amphidinium Carterae in the density of $0.5$\times$10^4$ cells/mL was died in 20 minutes when the phytoplankton was illuminated with UV-radiation without photocatalyst.

• 한국결정성장학회지
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• 제8권3호
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• pp.442-447
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• 1998

스파크 제조법으로 제조된 Ge 및 양극산화 부식법으로 제조된 다공성 Ge으로부터 청색 및 녹생 영역에서 가시광선 광발광이 관찰되었다. 자외선 조사없이 양극산화 부식법으로 제조된 다공성 Ge은 광발광 피크의 최대값이 520nm(2.38eV)에서, 자외선 조사하에서는 470nm(2,63eV)로 청색전이가 되었다. 스파크법으로 제조한 Ge은 광발광 피크가 520nm에서 관찰되었고 420nm 및 610nm에서 shoulder 피크가 나타났다. 온도감소(300K에서 20K까지)에 따른 연속적인 광발광 피크의 청색전이값은 자외선 조사하에 양극 산화부식법으로 제조한 다공성 Ge에서는 0.53meVK-1이었고 자외선 조사없이 제조한 다공성 Ge에서는 약 3배정도 큰 값인 $1.89\;meVK^{-1}$을 나타내었다. 한편 스파크 방법에 의하여 제조된 Ge은 온도 감소에 따른 연속적인 광발광 피크 청색 전이가 나타나지 않았다. 이러한 온도에 따른 광발광 현상으로부터 청색 및 녹색 광발광 현상을 나타내는 Ge의 광발광기구를 고찰하였다.

• 한국레이저가공학회지
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• 제18권1호
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• pp.18-22
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• 2015

In this paper, controlling shape of optical fiber tip for endoscope was investigated for eliminating blind spot. The blind spot of endoscope is generated by divergence angle of optical fiber, so it is easy to generate blind spot when tightly focusing. In order to eliminate this region, fiber tip is necessary to be controlled as convex or concave. Illumination simulation of convex and concave type of fiber tip in the endoscope was in progress, so the distance of non- blind region was investigated in each case. As well as the simulation, the tip was fabricated as concave shape by UV laser machining. Then the beam radiation was measured to observe the blind region. The result showed that controlling the fiber tip as convex or concave shape makes the narrow blind region of illumination in endoscope.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2003년도 International Meeting on Information Display
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• pp.528-530
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• 2003

We present a novel photo-addressable electronic paper using an electrophoretic device, which can show and sustain the 2D images transferred by the UV illumination. The device consists of the organic photoconducting layer reacting with the UV illumination and the electronic ink (white particles and blue dye) dispersing in a suspending medium. The voltage impression under illuminating of UV make an image be transferred to the electrophoretic cell. The transferred image can be maintained by the bistability of the electrophoretic device.

• Current Applied Physics
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• 제18권12호
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• pp.1496-1506
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• 2018

Organic/inorganic ultraviolet photodetector was fabricated using thermal evaporation technique. Organic/inorganic heterojunction based on thermally evaporated copper (II) acetylacetonate thin film of thickness 200 nm deposited on an n-type silicon substrate is introduced. I-V characteristics of the fabricated heterojunction were investigated under UV illumination of intensity $65mW/cm^2$. The diode parameters such as ideality factor, n, barrier height, ${\Phi}_B$, and reverse saturation current, $I_s$, were determined using thermionic emission theory. The series resistance of the fabricated diode was determined using modified Nord's method. The estimated values of series resistance and barrier height of the diode were about $0.33K{\Omega}$ and 0.72 eV, respectively. The fabricated photodetector exhibited a responsivity and specific detectivity about 9 mA/W and $4.6{\times}10^9$ Jones, respectively. The response behavior of the fabricated photodetector was analyzed through ON-OFF switching behavior. The estimated values of rise and fall time of the present architecture under UV illumination were about 199 ms and 154 ms, respectively. Finally, enhancing the photoresponsivity of the fabricated photodetector, post-deposition plasma treatment process was employed. A remarkable modification of the device performance was noticed as a result of plasma treatment. These modifications are representative in a decrease of series resistance and an increase of photoresponsivity and specific detectivity. The process of plasma treatment achieved an increment of external quantum efficiency from 5.53% to 8.34% at -3.5 V under UV illumination.

• 한국결정학회지
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• 제12권3호
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• pp.177-181
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• 2001

TiO₂박막의 초친수성 특성을 열처리에 따른 박막의 결정구조 변화와 연관지어 연구하였다. 박막은 Sol-Gel법을 이용하여 실리콘 (100)웨이퍼 위에 제조하였다. 1차 소결후, 500℃에서 후열처리한 시편은 anatase 상을, 1000℃에서 열처리한 시편은 rutile 상을 가지며 그 중판 온도인 750℃에서 열처리한 경우는 anatase와 rutile상이 혼재 되어 있다. 이 후열 처리한 시편들은 UV를조사하지 않아도 친수성을 보였고, 특히 750℃에서 열처리한 시편은 5°이하의 초친수성을나타내었다. 친수성을 가지는 시편들은 암실처리 중 서서히 퇴화되어 소수성을 띄게되지만, UV를 조사하면 1시간 이내에 급격히 초진수성을 회복하는 우수한 특성을 보였다.