• Title/Summary/Keyword: ultra-violet

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A Study on Enhancement of UV Disinfection System Performance by the Vortex Generator (와동 발생기를 이용한 자외선 살균 시스템 성능 향상에 관한 연구)

  • Kim, Bong-Hwan;Ahn, Kook-Chan;Kim, Dong-Jin
    • Journal of the Korean Society of Safety
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    • v.22 no.1 s.79
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    • pp.24-29
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    • 2007
  • The effectiveness of a UV(ultra violet) disinfection system depends on the characteristics of the waste water, flow conditions, the intensity of UV radiation, the amount of time the microorganisms are exposed to the radiation, and the reactor configuration. The wast water flow conditions are important factors in the design of UV disinfection system from the point of enhancement view of UV disinfection. The turbulent energy intensity in the wake by the vortex shedding are effective for UV radiation. Therewith the effectiveness of vortex generator is considered as a enhancement of UV disinfection. The experimental results presented give important evidences and explain that it is possible to predict UV disinfection performance based on flow experiments. An experimental investigation of two types of the vortex generator is presented. The qualitative and quantitative evaluations of the wake are made by flow visualization using smoke wire method and the measurement of vortex frequencies in the wind tunnel. From the experiment, following results were obtained that the delta wing type vortex generator is more effective than circular type because of the higher vortex frequencies and the smaller drag.

Comparison of UV images and Measurement of the Corona Discharge from Insulators using the UV Sensor (UV 센서를 이용한 절연애자의 코로나 방전 측정 및 자외선 이미지의 비교)

  • Kim, Young-Seok;Choi, Myeong-Il;Kim, Chong-Min;Bang, Sun-Bae;Shong, Kil-Mok
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.60 no.4
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    • pp.899-904
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    • 2011
  • Inspections and diagnoses of corona discharge are important in order to prevent electrical faults of external insulation in power systems. This paper studies a measurement of ultra-violet rays(UV) strength of corona discharges on insulators using a UV sensor with an optic lens. The data has been compared with the images of a UV camera. The UV sensor estimated that DC voltage needed to be set at 700V for accurate data analysis of the properties of UV detected during corona discharge. UV was generated at 60kV when the corona discharge occurred. UV strength and images of UV increased at a high voltage. The image area of the UV using a UV camera and the detection of UV using a UV sensor have shown, that the polymer insulator mounted on a live part must be checked when the applied voltage on the good polymer insulator is greater than 37.5% of its breakdown voltage.

Relation Between Defect State and Negative Ultra-Violet Photoresponse from n-ZnO/p-Si Heterojunction Diode

  • Jo, Seong-Guk;Nam, Chang-U;Kim, Eun-Gyu
    • Proceedings of the Korean Vacuum Society Conference
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    • 2013.08a
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    • pp.191.2-191.2
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    • 2013
  • The negative photoconductivity was frequently observed in some semiconductors. It was known that the origin of the negative photoresponse from ZnO is molecular chemisorption or the charging effect of nanoparticles in bulk matrix. However, the origin of the negative photoresponse of thin film was not still clear. One of possible explanation is due to the deep level trap scheme, which describes the origin of the negative photoresponse via defect state under illumination of light. However, the defect states below Fermi level have high capture rate by Coulomb effect, so that these states are usually filled by electrons if the defect states have donor-like character. Therefore the condition which the defect states located in below Fermi level should be partially filled by electrons make more difficult to understand of mechanism of the negative photoresponse. In this study, n-ZnO/p-Si heterojunction diodes were fabricated by UHV RF magnetron sputter. Then, some diodes show the negative photoresponse under ultra-violet light illumination. The defect state of the ZnO was analyzed by photoluminescence and deep level transient spectroscopy. To interpret the negative photoconductivity, band diagram was simulated by using SCAPS program.

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Study on Compound Humidifier Employing UV-LED using Environmental Life Cycle Assessment (환경전과정평가에 기반한 UV-LED 를 사용한 복합식 가습기에 관한 연구)

  • Choi, Won-Sik;Park, Si-Hyun;Lee, Si-Wang;Jung, Young-Mi;Yi, Hwa-Cho
    • Journal of the Korean Society for Precision Engineering
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    • v.29 no.9
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    • pp.931-937
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    • 2012
  • In this study, we assessed environmental impacts of compound humidifiers using environmental life cycle assessment and presented the ways to improvements in energy consumption of them. We found eco-design parameters and $CO_2$-eq emissions in each stage of raw material acquisition, manufacturing, transportation, use and disuse in life cycle of the compound humidifiers. The highest $CO_2$ emission is found to be in the stage of use among all stages of life cycle, which is mainly due to power consumption in thermal heating of heating coil for sterilization during humidification. The power consumption and $CO_2$ emission in the stage of use can be reduced to 1/4 and 1/3 at the highest estimate through improvement of sterilization method, respectively. We suggested the replacement of conventional thermal heating coil by ultra violet light-emitting diodes (UV-LED) for sterilization and then presented the experimental results on the sterilization effects of UV-LEDs.

Productivity of Polysaccharide by Mutant of Acetobacter pasteurianus IFO 13751 (Acetobacter pasteurianus IFO 13751의 돌연변이주에 의한 다당류 생산성)

  • Kim, Dong-Seuk;Ryu, Beung-Ho
    • Korean Journal of Food Science and Technology
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    • v.23 no.3
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    • pp.291-295
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    • 1991
  • In order to obtain the highest productivity of polysaccharide, acetic acid bacteria was used. Several acetic acid bacteria were investigated to the productivity of polysaccharide, an mutant, Acetobacter pasteurianus IFO 13751-5 selected among serveral acetic acid bacteria which can produce the polysaccharide by radiation of ultra-violet ray. Acetobacter pasteurianus IFO 13751-5 was shown 3 fold polysaccharide production than that of its parents. When the Acetobacter pasteurianus IFO 13751-5 was investigated under the condition of carbon source containing 5% sucrose, the highest amount of polysaccharide (45.95 mg/ml) was obtained. The polysaccharide production by Acetobacter pasteurianus IFO 13751-5 was 55.10 mg/ml by using jar fermentor.

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Automatic Extraction of UV patterns for Paper Money Inspection (지폐검사를 위한 UV 패턴의 자동추출)

  • Lee, Geon-Ho;Park, Tae-Hyoung
    • Journal of the Korean Institute of Intelligent Systems
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    • v.21 no.3
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    • pp.365-371
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    • 2011
  • Most recently issued paper money includes security patterns that can be only identified by ultra violet (UV) illuminations. We propose an automatic extraction method of UV patterns for paper money inspection systems. The image acquired by camera and UV illumination is transformed to input data through preprocessing. And then, the Gaussian mixture model (GMM) and split-and-merge expectation maximization (SMEM) algorithm are applied to segment the image represented by input data. In order to extract the UV pattern from the segmented image, we develop a criterion using the area of covariance vector and the weight value. The experimental results on various paper money are presented to verify the usefulness of the proposed method.

Leakage Analysis of Air Bearing for Vacuum Environment (진공환경용 공기베어링의 Leakage 해석)

  • 김경호;박천홍;이후상;김승우
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 2004.10a
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    • pp.912-915
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    • 2004
  • A vacuum environment is very important for NGL(Next Generation Lithography) apparatuses such as EUVL(Extreme Ultra Violet Lithography) or EPL(Electron Projection Lithography) and so on. The performance of these systems is dominated by vacuum level of processing and positioning accuracy of a stage. So, ultra-precision stage usable in a high vacuum level is needed for the improved performance of these devices. In contrast to atmospheric condition, a special attention must be paid to guide bearing, actuator and other elements. In this paper, air bearing is adopted because of its very high motional accuracy. So, air bearing is designed to be vacuum compatible using differential exhaust method, which prevents air from entering into vacuum chamber. For this, leakage analysis is performed theoretically and verified from experiment.

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Design of the self-oscillation UV flash lamp power supply and the characteristic of its operation using self-resonance of the transformer (트랜스포머의 자가 공진(Self-Resonance)특성을 이용한 자가 발진(Self-Oscillation) UV(Ultra Violet) 발생 플래시램프 전원장치설계 및 그 동작 특성)

  • Kim, Shin-Hyo;Cho, Dae-Kweon
    • Journal of Advanced Marine Engineering and Technology
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    • v.38 no.1
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    • pp.48-55
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    • 2014
  • These Xenon flashlamp power supply for Ultra Violet has converter with high voltage conversion ratio. General model is composed of transformer with high voltage conversion ratio and voltage doubler rectifier circuit. Purpose of power supply leads dielectric breakdown of Xenon flashlamp and passes current rapidly. When passing current, it has to limit current to avoid over-heat, damage of electrode and acceleration of gas oxidation which are cause of performance degradation of lamps. Generally, inductors and resistors, which are called as "Ballast," are used to limit currents. Generally, Transformer has high turn ratio to make high voltages. But we can get high voltages using the transformer with low turn ratio which is driven with self resonance. Also, an advantage of self resonance is to make a circuit simply through impedance of transformer in resonance frequency which filters output voltage. As using an unique impedance of transformer, the circuit does not need other impedance elements like the ballast. So the power supply assures high efficiency of the arc discharge.

Tests on Superplasticizers for High Strength Concrete (고강도 콘크리트용 고성능감수제 성능평가)

  • 노재호;김기철;조일호;한정호;박연동
    • Proceedings of the Korea Concrete Institute Conference
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    • 1994.10a
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    • pp.151-156
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    • 1994
  • This study is to investigate the quality of superplasticizers in domestic market. Therefore, the physico-chemical characteristics, the fluidity characteristics of fresh cement paste and mortar were tested. Also fresh and hardened properties of mortars and concretes using these superplasticizers were tested. From these results, differences of quality among superplasticizers are checked clearly in low water/cement ratio. And it is concluded that several superplasticizers have better dispersion ability than others in every tests. It has known that all samples are naphtalene sulfornate formaldehede types by the UV(ultra-violet) test.

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Study on Inclusion Complex of Fenbufen with ${\beta}-Cyclodextrin$

  • Kim, Young-Il;Park, Young-Ju
    • Journal of Pharmaceutical Investigation
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    • v.14 no.3
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    • pp.136-143
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    • 1984
  • Inclusion complex formation of fenbufen with ${\beta}-cyclodextrin$ in water and in solid state was comfirmed by solubility method, ultra violet absorption, circular dichroism and infra-red spectroscopies, differential thermal analysis, and X-ray diffractometry. A solid complex of fenbufen with ${\beta}-cyclodextrin$ in 1 : 1 molar ratio was prepared by the freeze-drying method, its dissolution characteristics in water and its analgesic and antiinflammatory effect in mouse or rat were examined. The apparent release of fenbufen from the inclusion complex was significantly improved, hut no significant difference in its analgesic and antiinflammatory effect was found.

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