• Journal of Sensor Science and Technology
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• v.20 no.3
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• pp.156-161
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• 2011

We fabricated a schottky barrier metal oxide semiconductor field effect transistor(SB-MOSFET) by applying indium-tin-oxide(ITO) to the source/drain on a highly resistive GaN layer grown on a silicon substrate. The MOSFET, with 10 ${\mu}M$ gate length and 100 ${\mu}M$ gate width, exhibits a threshold gate voltage of 2.7 V, and has a sub-threshold slope of 240 mV/dec taken from the $I_{DS}-V_{GS}$ characteristics at a low drain voltage of 0.05 V. The maximum drain current is 18 mA/mm and the maximum transconductance is 6 mS/mm at $V_{DS}$=3 V. We observed that the spectral photo-response characterization exhibits that the cutoff wavelength was 365 nm, and the UV/visible rejection ratio was about 130 at $V_{DS}$ = 5 V. The MOSFET-type UV detector using ITO, has a high UV photo-responsivity and so is highly applicable to the UV image sensors.

• Journal of Crop Science and Biotechnology
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• v.10 no.3
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• pp.163-166
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• 2007

Diurnal changes in levels of endogenous gibberellins(GAs) were investigated in three rice cultivars i.e. Sangjubyeo, Shingeumobyeo(photo-neutral) and Chucheongbyeo(photosensitive). The rice cultivars were grown under a 12-hr photoperiod and endogenous GA levels were assayed by gas chromatography-mass spectrometry(GC-MS-SIM) every 3 h for 24 h. The endogenous bioactive $GA_1$ and its immediate precursor $GA_{20}$ contents were significantly different in both photosensitive and photo-neutral rice cultivars, though less pronounced differences were observed for endogenous $GA_{12},\;GA_{53},\;GA_{19}$, and $GA_8$ levels with in the three rice cultivars. The levels of bioactive $GA_1$ and its immediate precursor $GA_{20}$ were significantly higher in Chucheongbyeo than in the other two cultivars. In Chucheongbyeo, the $GA_1$ contents increased significantly from 11.00 to 17.00 o'clock, thus indicating a correlation with light. In Shingeumobyeo, $GA_1$ contents slightly increased during morning hours, while a similar hike in $GA_1$ contents was observed for Sangjubyeo during evening hours. $GA_{19}$ was found to be the most abundant GA form in the three rice cultivars. Our results suggested that GA production in rice depends upon the response potential of rice cultivars and that light positively correlated to GA production in photosensitive rice cultivar.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.02a
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• pp.193-194
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• 2012

그래핀(graphene)은 탄소원자가 육각형 벌집 모양 배열의 격자구조를 가지는 원자 한층 두께의 이차원 물질이다. 그래핀은 전도띠(conduction band)와 가전자띠(valence band)가 한 점에서 만나고 에너지와 역격자의 k 벡터가 선형적으로 비례하는 에너지 구조를 가진다. 이로 인해 그래핀은 매우 빠른 전하 이동도를 가지며 원자 한 층의 두께임에도 불구하고 약 2.3%의 빛을 흡수할 수 있으며 자외선 영역부터 적외선 영역까지의 넓은 파장대의 빛을 흡수 할 수 있다. 이와 같은 그래핀의 우월한 성질을 이용하면 광 응답에 고속으로 반응하고 높은 주파수의 광통신에서도 작동 할 수 있는 그래핀 광소자를 제작할 수 있게 된다. 하지만 미래의 고속 그래핀 광소자를 실현하기에 앞서 그래핀의 광응답에 대한 정확한 이해가 필요하다. 그리하여 본 연구에서는 그래핀 광소자를 제작하고 광소자의 광응답 전기적 성질을 분석하여 그래핀의 광응답 특성을 얻어내고자 실험을 진행하였다. 그래핀을 채널 물질로 하고 소스, 드레인, 후면 게이트를 가지는 일반적인 그래핀 전계효과 트랜지스터(field-effect transistor)를 제작하고 채널에 빛을 비추고 비추지 않은 상태에서의 전기적 성질을 측정하고 그 때 얻어진 그래프의 광응답의 원인을 조사하였다. 이 때 얻어지는 $I_D-V_G$ 그래프가 광 조사 시 왼쪽으로 이동하게 되는데 이의 원인을 각 게이트 전압 구간별로 $I_D$-t 그래프를 획득하여 분석하였다. 또한 광원에 펄스를 인가하여 펄스 형태의 광원을 그래핀 전계효과 트랜지스터에 조사시키고 이에 따른 전기적 성질 변화를 관찰하였다 이 때 다양한 게이트 전압이 인가된 상태에서 레이저 펄스 광원에 의한 광전류를 검출하였으며 이를 분석하였다.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.67 no.6
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• pp.789-793
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• 2018

All transparent metal oxide photoelectric device based on $V_2O_5$ was fabricated with structure of $V_2O_5/ZnO/ITO$ by magnetron sputtering system. $V_2O_5$ was deposited by reactive sputtering system with 4 inch vanadium target (purity 99.99%). In order to achieve p-n junction, p-type $V_2O_5$ was deposited onto the n-type ZnO layer. The ITO (indium tin oxide) was applied as the electron transporting layer for effective collection of the photo-induced electrons. Electrical and optical properties were analyzed. The Mott-Schottky analysis was applied to investigate the energy band diagram through the metal oxide layers. The $V_2O_5/ZnO/ITO$ photoelectric device has a rectifying ratio of 99.25 and photoresponse ratios of 1.6, 4.88 and 2.68 under different wavelength light illumination of 455 nm, 560 nm and 740 nm. Superior optical properties were realized with the high transmittance of average 70 % for visible light range. Transparent $V_2O_5$ layer absorbs the short wavelength light efficiently while passing the visible light. This research may provide a route for all-transparent photoelectric devices based on the adoption of the emerging p-type $V_2O_5$ metal oxide layer.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.30 no.3
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• pp.314-319
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• 1985

In order to observe the differences of several characters related to earliness, seven barley varieties were tested under two different photoperiodic conditions. Final leaf number per main stem under long day did not vary among varieties, but ranged 6 to 7 in early group and 9 to 10 in late group under shortday. Shoot apex of early varieties, Jogangbori and Oweolbori reached to X stage at 24 days, but that of late variety, CI 15446 did to X stag at 32 days after transplanting under short day. Spike length reached to maximum length at 39 days in early group, but at 51 days in late group. Saeolbori, CI 15446 and Hangmi were photo-sensitive, but Jogangbori and Oweolbori were photo-insensitive. Therefore, the photoperiodic response to short day was most responsible to heading time. Those results showed that early heading varieties had the characteristics with less variation of final leaves, less retardation of shoot apex development and spike elongation, and shorter period to flag leaf emergence under short day.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2017.05a
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• pp.612-616
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• 2017

An experimental study investigates the flame response characteristics of non-premixed flame and premixed flame. Air was used as the oxidant. Hydrogen($H_2$)/methane($CH_4$) was used as the fuel, and the mixing ratio of the fuel was 50/50%. Flame response characteristics for various velocity perturbations were experimented. The flame images was acquired using the OH fluorescence measurement and the images were digitized using MatLab code. The results of the premixed flame show that flame perturbation increases as the oscillation amplitude increases. As the amplitude increases, the gain value of the flame transfer function is observed to be a linear behavior. The flame length of a nonpremixed flame decreases as the oscillation amplitude increases. Also, it was confirmed that the gain value according to the amplitude behaves nonlinearly.

• Restorative Dentistry and Endodontics
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• v.22 no.2
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• pp.720-730
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• 1997

This study was performed to observe the histopathological response to the bonding resin directly applied on the remaining pulp tissues. 40 teeth from 3 adult dogs were pulpotomized with a sterile round bur and sharp excarvater. In the control group, $Ca(OH)_2$ powder was applied on the pulp tissue and the cavities were sealed with IRM cement. In the experimental group 1, Superbond C&B was applied on the remaining pulp and the cavities conditioned with 10-3 solution were filled with the mixture of the MMA liquid, PMMA powder and Catalyst. Multi-purpose adhesive was used on the remaining pulp tissue in the experimental group 2 and Z-100 was filled in the cavities. In the experimental group 3, Clearfil photobond applied and directly photo-cured on the pulp tissue, then the cavities were treated with CA agent (10% citric acid and 20% $CaCl_2$ aqueous solution) for 20 seconds, washed and applied with Clearfil photobond then filled with Protect liner. The experimental animals were sacrified at the 1st, 2nd, and 4th week. The specimens were routinely processed and stained with H-E for light microscopic observation. The results were as followed : 1. In the experimental group 1, the number and characteristics of the dentin bridge formation case was similar to those in the control group and less cases were observed in the experimental group 2 and 3 than experimental group 3. The inflammatory response in experimental group 1 was less than that in the control group at 1st week but there had been little difference at between 2nd and 4th week. 2. The number of the dentin bridge in experimental group 2 was less than that in control group and experimental group 1. The inflammatory response of the experimental group 1 was similar to that of experimental group 1 but less than that of the control group. A number of bleeding and vascular congestion were observed. The least inflammatory response was seen in the experimental group 2 among all groups. 3. In the experimental group 3, one case of the dentin bridge formation was observed and that was the same as that in the experimental group 2 but smaller than that of the control and experimental group 1. The inflammatory response of the experimental group 3 was least at the 1st week and most at the 4th week in the all group.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.14 no.2
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• pp.118-126
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• 2009

Benthic diatoms are very important primary producers in understanding estuary ecosystems and their productions are largely varied by their photo-physiological characteristics. The short-term effects of increased temperature on the photosynthetic and photo-physiological characteristics of cultured different species of benthic diatoms (Navicula sp., Nitzschia sp., Cylindrotheca closterium, and Pleurosigma elongatum) were investigated by measuring their PSII-fluorescence kinetics using a Diving-PAM. Photosynthesis versus irradiance curves were measured every two hours at six different temperatures (10, 15, 20, 25, 30, and $35^{\circ}C$) for twenty-four hour. The effective quantum yield of PSII ($\Phi_{PSII}$) for most of the species showed a decreasing trend with increased temperature. The relative maximum electron transport rate (rETRmax) was significantly increased up to the optimum temperature level and then sharply decreased. Relative to the values of other parameters, the maximum light use coefficient ($\alpha$) was not substantially changed at lower temperature levels (<$30^{\circ}C$) but significantly decreased only at higher temperatures (30 and $35^{\circ}C$). The light saturation coefficient ($E_K$) mirrored the rETRmax temperature response. In regards to the temperature acclimation abilities of the four species with time, Navicula sp. and C. closterium acclimated to short-term changes in temperature through their photo-physiological adjustments.

• Interdisciplinary Bio Central
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• v.1 no.1
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• pp.1.1-1.5
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• 2009

Many organisms control their physiology and behavior in response to the local light environment, which is first perceived by photoreceptors that undergo light-dependent conformational changes. Phytochromes are one of the major photoreceptors in plants, controlling wide aspects of plant physiology by recognizing the light in red (R) and far-red (FR) spectra. Higher plants have two types of phytochromes; the photo-labile type I (phyA in Arabidopsis) and photo-stable type II (phyB-E in Arabidopsis). Phytochrome B (phyB), a member of the type II phytochromes in Arabidopsis, shows classical R and FR reversibility between the inter-convertible photoisomers, Pr and Pfr. Interestingly, the Pr and Pfr isomers show partitioning in the cytosol and nucleus, respectively. In the over 50 years since its discovery, it has been thought that the type II phytochromes only function to mediate R light. As described in the text, we have now discovered phyB has an active function in FR light. Even striking is that the R and FR light exert an opposite effect. Thus, FR light is not simply nullifying the R effect but has an opposing effect to R light. What is more interesting is that the phyB-mediated actions of FR and R light occur at different cellular compartment of the plant cell, cytosol and nucleus, respectively, which was proven through utilization of the cytosolic and nuclear-localized mutant versions of phyB. Our observations thus shoot down a major dogma in plant physiology and will be considered highly provocative in phytochrome function. We argue that it would make much more sense that plants utilize the two isoforms rather than only one form, to effectively monitor the changing environmental light information and to incorporate the information into their developmental programs.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.40 no.1
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• pp.31-40
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• 2022

The importance of disaster management and response is emerging as various disasters such as COVID-19, torrential rains, and fires occur one after another. In addition, in order to respond efficiently throughout disaster response activities, it is necessary to quickly collect disaster site information and quickly check the site situation through photo and video information so that rapid disaster response can be achieved. In this study, essential information required for decision-making was derived by analyzing the essential activities of each disaster response stage, analyzing the crisis management standard manual and related laws for each disaster type, and daily comprehensive report. In addition, a list of information necessary to grasp the situation of the disaster site and grasp the status of real-time damage was derived to establish guidelines for collecting volatile disaster site information, and disaster situation information can be efficiently displayed through a spatial information-based display system. By presenting essential disaster management information to be collected first, the person in charge of collecting information can efficiently collect information, and the situation room in charge of disaster response decision-making is expected to enable more efficient disaster situation management by receiving only the necessary information.