• Title/Summary/Keyword: low light intensity

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Effects of Light and Storage Condition on the Germination of Oenothera lamarckiana Seeds (큰달맞이꽃 종자(種子)의 발아(發芽)에 미치는 광(光) 및 저장조건(貯藏條件)의 영향)

  • Kim, J.S.;Hwang, I.T.;Koo, S.J.;Cho, K.Y.
    • Korean Journal of Weed Science
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    • v.7 no.2
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    • pp.130-138
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    • 1987
  • The effects of light and storage conditions on the germination of Oenothera lamarckiana were investigated. Germination was induced by red light, but inhibited by green, blue or infrared. No germination occurred in the dark. Radicle was more photosensitive than other parts of the seed. The rate of germination was proportional to increase in Light intensity ranging from 10 to 3000 Lux. Photosensitivity occurred 6 hrs after water imbibition of air-dried seeds. Maximum photosensitivity was detected 1-2 days after seeding under the light condition at 300 Lux. Germination was almost completed 3 days after seeding. When seeds stored in the chilling and wetting condition were kept at constant temperature in the dark, they germinated well. Air-dried seeds, however, didn't germinate. Whereas, the seeds which kept at alternating temperature had the tendency that seeds stored at room temperature (25$^{\circ}C$) germinated better than those stored at low temperature (4$^{\circ}C$).

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Flavor and taste characteristic of black pepper by different nonthermal sterilization methods (비가열 살균 후추의 향미특성)

  • Lee, Gwang Min;Shin, Jung Kue
    • Korean Journal of Food Science and Technology
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    • v.51 no.6
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    • pp.551-557
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    • 2019
  • The purpose of this study was to investigate the changes of flavor and taste characteristics of black pepper treated with three different nonthermal sterilization methods, which are intense pulsed light (IPL), ultraviolet (UV), and cold plasma (CP). Also, the sensorial and instrumental evaluation of black pepper before and after nonthermal treatments were analyzed. As a result of color value, UV and CP treatments did not show chromacity difference (ΔE), but IPL treatment showed a significant difference of 6.58. Piperine contents of sample before nonthermal treatments was 10.7±0.53 mg/g and the piperine contents of all samples decreased after nonthermal treatments. The result of the electronic nose analysis were divided into two groups before and after nonthermal treatments, and divided into three group by principle component analysis. According to the intensity test, after nonthermal treatments, all sample had low flavor and taste, and the intensity was in the order of IPL, CP, and UV. In thirteen sensory attribute languages developed through quantitiative descriptive analysis (QDA), the intensity value of the samples were low after nonthermal treatments.

Control of Size and Morphology of Particles Using CO2 Laser in a Flame (화염증 CO2 Laser를 이용한 입자의 크기 및 형상 제어)

  • Lee, Donggeun;Lee, Seonjae;Choi, Mansoo
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.23 no.11
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    • pp.1379-1389
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    • 1999
  • A new technique for control of size and shape of flame-made particles is Introduced. The characteristic sintering time can be controlled Independently of collision time by heating the particles with irradiation of laser because the sintering time strongly depends on temperature. A coflow oxy-hydrogen diffusion flame burner was used for $SiCl_4$ conversion to silica particle. Nanometer sized aggregates irradiated by a high power CW $CO_2$ laser beam were rapidly heated up to high temperatures and then were sintered to approach volume-equivalent spheres. The sphere collides much slower than the aggregate, which results in reduction of sizes of particles maintaining spherical shape. Light scattering of Ar ion laser and TEM observation using a local sampling device were used to confirm the above effects. When the $CO_2$ laser was irradiated at low position from the burner surface, particle generation due to gas absorption of laser beam occurred and thus scattering intensity increased with $CO_2$ laser power. At high irradiation position, scattering intensity decreased with $CO_2$ laser power and TEM image showed a clear mark of evaporation and recondensation of particles for high $CO_2$ laser power. When the laser was irradiated between the above two positions where small aggregates exist, average size of spherical particles obviously decreased to 58% of those without $CO_2$ laser irradiation with the spherical shape. Even for increased carrier gas flow rate by a factor of three, TEM photograph also revealed considerable reduction of particle size.

Graphene Formation on Ni/SiO2/Si Substrate Using Carbon Atoms Activated by Inductively-Coupled Plasma Chemical Vapor Deposition (유도결합 플라즈마 화학기상증착법에 의해 활성화된 탄소원자를 이용한 Ni/SiO2/Si 기판에서 그래핀 성장)

  • Nang, Lam Van;Kim, Eui-Tae
    • Korean Journal of Materials Research
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    • v.23 no.1
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    • pp.47-52
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    • 2013
  • Graphene has been synthesized on 100- and 300-nm-thick Ni/$SiO_2$/Si substrates with $CH_4$ gas (1 SCCM) diluted in mixed gases of 10% $H_2$ and 90% Ar (99 SCCM) at $900^{\circ}C$ by using inductively-coupled plasma chemical vapor deposition (ICP-CVD). The film morphology of 100-nm-thick Ni changed to islands on $SiO_2$/Si substrate after heat treatment at $900^{\circ}C$ for 2 min because of grain growth, whereas 300-nm-thick Ni still maintained a film morphology. Interestingly, suspended graphene was formed among Ni islands on 100-nm-thick Ni/$SiO_2$/Si substrate for the very short growth of 1 sec. In addition, the size of the graphene domains was much larger than that of Ni grains of 300-nm-thick Ni/$SiO_2$/Si substrate. These results suggest that graphene growth is strongly governed by the direct formation of graphene on the Ni surface due to reactive carbon radicals highly activated by ICP, rather than to well-known carbon precipitation from carbon-containing Ni. The D peak intensity of the Raman spectrum of graphene on 300-nm-thick Ni/$SiO_2$/Si was negligible, suggesting that high-quality graphene was formed. The 2D to G peak intensity ratio and the full-width at half maximum of the 2D peak were approximately 2.6 and $47cm^{-1}$, respectively. The several-layer graphene showed a low sheet resistance value of $718{\Omega}/sq$ and a high light transmittance of 87% at 550 nm.

Evaluation of wireless communication devices for remote monitoring of protected crop production environment (시설재배지 환경 원격 모니터링을 위한 무선 통신 장비 평가)

  • Hur, Seung-Oh;Ryu, Myong-Jin;Ryu, Dong-Ki;Chung, Sun-Ok;Huh, Yun-Kun;Choi, Jin-Yong
    • Korean Journal of Agricultural Science
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    • v.38 no.4
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    • pp.747-752
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    • 2011
  • Wireless technology has enabled farmers monitor and control protected production environment more efficiently. Utilization of USN (Ubiquitous Sensor Network) devices also brought benefits due to reduced wiring and central data handling requirements. However, wireless communication loses signal under unfavorable conditions (e.g., blocked signal path, low signal intensity). In this paper, performance of commercial wireless communication devices were evaluated for application to protected crop production. Two different models of wireless communication devices were tested. Sensors used in the study were weather units installed outside and top of a greenhouse (wind velocity and direction, precipitation, temperature and humidity), inside ambient condition units (temperature, humidity, $CO_2$, and light intensity), and irrigation status units (irrigation flow and pressure, and soil water content). Performance of wireless communication was evaluated with and without crop. For a 2.4 GHz device, communication distance was decreased by about 10% when crops were present between the transmitting and receiving antennas installed on the ground, and the best performance was obtained when the antennas were installed 2 m above the crop canopy. When tested in a greenhouse, center of a greenhouse was chosen as the location of receiving antenna. The results would provide information useful for implementation of wireless environment monitoring system for protected crop production using USN devices.

Effects of Preparation Conditions in the Spray Pyrolysis on the Characteristics of Ca8Mg(SiO4)4Cl2:Eu2+ Phosphor (분무열분해 공정의 제조 조건이 Ca8Mg(SiO4)4Cl2:Eu2+ 형광체 특성에 미치는 영향)

  • Han, Jin-Man;Koo, Hye-Young;Lee, Sang-Ho;Kang, Yun-Chan
    • Korean Journal of Materials Research
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    • v.18 no.2
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    • pp.92-97
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    • 2008
  • In spray pyrolysis, the effects of the preparation temperature, flow rate of the carrier gas and concentration of the spray solution on characteristics such as the morphology, size, and emission intensity of $Ca_8Mg(SiO_4)_4Cl_2:Eu^{2+}$ phosphor powders under long-wavelength ultraviolet light were investigated. The phosphor powders obtained post-treatment had a range of micron sizes with regular morphologies. However, the composition, crystal structure and photoluminescence intensity of the phosphor powders were affected by the preparation conditions of the precursor powders. The $Ca_8Mg(SiO_4)_4Cl_2:Eu^{2+}$ phosphor powders prepared at temperatures that were lower and higher than $700^{\circ}C$ had low photoluminescence intensities due to deficiencies related to the of Cl component. The phosphor powders with the deficient Cl component had impurity peaks of $Ca_2SiO_4$. The optimum flow rates of the carrier gas in the preparation of the $Ca_8Mg(SiO_4)_4Cl_2:Eu^{2+}$ phosphor powders with high photoluminescence intensities and regular morphologies were between 40 and 60 l/minute. Phosphor powders prepared from a spray solution above 0.5 M had regular morphologies and high photoluminescence intensities.

Habitat Characteristics and Distribution of Cymbidium kanran Native to Jejudo, Korea (제주한란의 자생환경 특성 및 분포에 관한 연구)

  • Lee, Jong Suk
    • Journal of the Korean Society of Environmental Restoration Technology
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    • v.7 no.1
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    • pp.40-49
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    • 2004
  • This work carried out to define the characteristic of Cymbidium kanran habitat at Mt. Halla in Jejudo, Korea from the ecological point of view including geological and topographical features, air and soil temperature, relative humidity, fluctuations of light intensity, habitat vegetation, distribution altitude, area limit, and etc. And another goal of this study consider the conservation counterplan of the cymbidium habitat. Natural distribution areas of the cymbidium were observed more abundantly on the well drained south and east-facing slopes. Soil acidity was ranged from pH 4.1 to 5.3, and electric conductivity was ranged from 176.4 to 299.9 us/cm (average 215.3 us/cm). Base-saturation percentage of the habitat soil was below 50%, bulk density 0.42g/$cm^2$, particle density 2.05g/$cm^2$, humus content 26%, total nitrogen 0.82%, available phosphate 4.2 mg/kg, exchangeable potassium 0.63 Cmol/kg, calcium 0.44 Cmol/kg and magnesium 0.67 Cmol/kg. Annual mean air temperature was $15.4^{\circ}C$, however, air temperature was ranged $11.7{\sim}18.2^{\circ}C$ in spring, $21.2{\sim}23.8^{\circ}C$ in summer, $12.8{\sim}22.0^{\circ}C$ in fall and $5.5{\sim}7.8^{\circ}C$ in winter season. Annual mean soil temperature at depth of 10cm was $13.2^{\circ}C$ And minimum value was recorded $4.7^{\circ}C$ on January, and maximum value $22.5^{\circ}C$ on August. Relative humidity was ranged 90.8~94.7% in summer, 80.8~91.5% in fall and 77.6~84.2% in winter season. Minimum value was 56.5% on December, and maximum value was 100% on July and August. Light intensities were ranged from 400 to 1,800 lux at the greater part of Cymbidium kanran sites in Jejudo. Summer regarded as an lower light intensities was recorded to be range of 500~600 lux; however, autumn and winter were shown higher light regimes ranged from 3,500 to 3,800 lux. Therefore, one must be suprised that the cymbidium grow at the light condition of 6 lux (minimum) or 10,000 lux (maximum). Tree species keeping higher frequency rate and density were Eurya japonica, Camellia japonica, Castanopsis cuspidata, Carpinus laxiflora and Pinus densiflora. Number of trees growing in a 5${\times}$5m quardrat was 35 as an average, and proportion of evergreen versus deciduous was 5:1. Distribution altitude of the orchid habitat was ranged from 120m (low) to 840m (high) from sea level on the south facing slope of Mt. Halla, and was ranged eastern borderline of Gujwaup, Bukjejugun to western boundaries of Jungmundong, Seogwipo city. For the stable conservation of Cymbidium kanran habitat, sunlight regimes must be increased more by means of cutting trees or twigs in the site.

Electric Corrosion of STS304 Acupuncture Needles Used for Electroacupuncture (STS304 스테인리스 강선 호침에서 전침 자극 후 침체에 나타나는 전기적 부식 연구)

  • Hwang, Hye-Suk;Koo, Sung-Tae;Ryu, Yeon-Hee;Jeong, Sang-Yong;Kim, Yu-Sung;Lee, Ji-Eun;Han, Kyung-Ju;Choi, Sun-Mi
    • Journal of Acupuncture Research
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    • v.24 no.5
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    • pp.105-111
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    • 2007
  • Objectives : The electroacupuncture(EA) was often used in Oriental medicine clinic and basic researches. However, there have been neither any national standard of acupuncture needles in Korea nor many studies about the property of acupuncture needles for applying electrical stimulations. Therefore we investigated the electrical corrosion property of acupuncture needles used for EA stimulation in clinic. Methods : We observed the occurrence of electrical corrosion like changes in the surface of acupuncture needles after EA stimulation with various parameters(electrical stimulation intensity, treatment duration, diameter of needle) under a light microscope. We performed EA stimulation on Baekhoe($GV_{20}$) or Joksamli($ST_{36}$) of rats with intensity of 0.025, 0.05, 0.075, 0.1, 0.25 or 0.5mA at a 10Hz frequency. Results : The electrical corrosion-like changes were found on the surface of needles when the EA stimulation was given over 0.05mA of intensity. When electrical stimulation was treated for 10min, the electrical corrosion-like changes were low, but the electrical corrosion-like changes gradually increased by the treatment duration(20, 30min). We also found that acupuncture needles of 0.2mm diameter were produced more extensive electrical corrosion-like changes than acupuncture needles of 0.3 or 0.4mm diameter by electrical stimulation. Conclusions: These results suggested that EA stimulation could produce electrical corrosion-like changes of acupuncture needles through intensity of current, duration of electric stimulation and/or diameter of needle.

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Electrochemical Properties of HNO3 Pre-treated $TiO_2$ Photoelectrode for Dye-SEnsitized Solar Cells (염료감응형 태양전지용 질산 전처리된 $TiO_2$ 광전극의 전기화학적 특성)

  • Park, Kyung-Hee;Jin, En-Mei;Gu, Hal-Bon
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2009.06a
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    • pp.441-441
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    • 2009
  • Dye-sensitized solar cells (DSSCs) have been widely investigated as a next-generation solar cell because of their simple fabrication process and low coats. The cells use a porous nanocrystalline TiO2 matrix coated with a sensitizer dye that acts as the light-harvesting element. The photo-exited dye injects electrons into the $TiO_2$ particles, and the oxide dye reacts with I- in the electrolyte in regenerative cycle that is completed by the reduction of $I_3^-$ at a platinum-coated counter electrode. Since $TiO_2$ porous film plays a key role in the enhancement of photoelectric conversion efficiency of DSSC, many scientists focus their researches on it. Especially, a high light-to-electricity conversion efficiency results from particle size and crystallographic phase, film porosity, surface structure, charge and surface area to volume ratio of porous $TiO_2$ electrodes, on which the dye can be sufficiently adsorbed. Effective treatment of the photoanode is important to improve DSSC performance. In this paper, to obtain properties of surface and dispersion as nitric acid treated $TiO_2$ photoelectrode was investigate. The photovoltaic characteristics of DSSCs based the electrode fabricated by nitric acid pre-treatment $TiO_2$ materials gave better performances on both of short circuit current density and open circuit voltage. We compare dispersion of $TiO_2$ nanoparticles before and after nitric acid treatment and measured Ti oxidized state from XPS. Low charge transfer resistance was obtained in nitric acid treated sample than that of untreated sample. The dye-sensitized solar cell based on the nitric acid treatment had open-circuit voltage of 0.71 V, a short-circuit current of 15.2 mAcm-2 and an energy conversion efficiency of 6.6 % under light intensity of $100\;mWcm^{-2}$. About 14 % increases in efficiency obtained when the $TiO_2$ electrode was treated by nitric acid.

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Effect of Temperture and Light on Growth of Leaf Lettuce(Lactuca sativa L. var. crispa cv. Cheongchima) in Hydroponics (배양액 온도 및 차광정도가 청치마 상추의 생육에 미치는 영향)

  • 남상용;권용웅
    • Journal of Bio-Environment Control
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    • v.6 no.4
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    • pp.270-276
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    • 1997
  • This experiment was conducted to develop a practical method to growth in hydroponics conditions. For this purpose, leaf lettuce (Lactuca sativa L., cv. 'Cheongchima') was cultivated under different temperature and light conditions in experimental fields of Sahmyook university from March, 1991 to May, 1996. The visual quality score(VQS), a quantitative parameter to evaluate harvested leaf lettuce quality. The leaf lettuce cultivated at $25^{\circ}C$ solution temperature showed the highest fresh weight pe, plant (59.7g/plant), but lowest visual quality score (5.2), while leaf lettuce cultivated at 15$^{\circ}C$ solution temperature showed lower fresh weight per plant (25.2g/plant) but highest visual quality score (7.2). In general, growth of leaf lettuce was retarded by low solution temperature, but quality was higher than those of other solution temperature. Different day/night temperature of nutrient solutions 20/2$0^{\circ}C$ and 25/2$0^{\circ}C$ was highest in yield, but leaf type was grow longer, and visual quality are inferior to low temperature. Yield was decreased as 10 and 25% at 60 and 80% shading treatment, respectively. Chlorophyll content was decreased by shading. but plant height and root length were increased of leaf lettuce growth with hydroponics.

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