• Title/Summary/Keyword: Laboratory characteristics

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Characteristics of High Voltage Discharge using Triggered Spark Gap (Trigged Spark Gap의 고전압 방전제어특성 연구)

  • Son, Yoon-Gyu;Kim, Kwang-Gi;Park, Sang-Wook;Cho, Moo-Hyun
    • Proceedings of the KIEE Conference
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    • 1997.07e
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    • pp.1816-1818
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    • 1997
  • A triggered sparkp gap switch was fabricater and its high-voltage discharge characteristics were studied. The switch is composed of two main electrodes and one trigger electrode which is placed perpendicular to the main one. Spark gap distance was fixed by 25 mm. This device has been operated without self firing at the pulse repetition frequency from 1 to 20 Hz limited by the charging current, and the hold-off voltage from 10 to 30kV. An IGBT switch and igniter coil (originally used in a car) were adopted for a trigger circuit. In this article preliminary switch characteristics of the spark gap switch are reported with the emphasis on the description of the trigger circuit.

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ELECTRICAL CHARACTERISTICS OF THIN DIELECTRIC FILMS PREPARED BY RAPID THERMAL PROCESS (RAPID THERAL PROCESS를 응용한 THIN DIELECTRIC FILM의 전기적 특성에 관한 연구.)

  • Lee, Ang-Goo;Park, Seong-Sik;Choi, Jin-Seog;Rhieu, Ji-Hyo
    • Proceedings of the KIEE Conference
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    • 1987.07a
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    • pp.542-545
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    • 1987
  • THE ELECTRICAL CHARACTERISTICS Of RAPID THERMAL OXIDES AND NITRIDED OXIDES HAVE BEEN INVESTIGATED. R.T.OXIDE FILMS HAVE BEEN PREPARED BY ONLY R.T. OXIDATION OR R.T.OXIDATION AND SUBSEQUENT R.T.ANNEAL. NITRIDED OXIDE FILMS HAVE BEEN PREPARED BY R.T.OXIDATION AND SUBSEQUENT R.T.NITRIDATION.AND CONVENTIONAL OXIDES ALSO HAVE BEEN PREPARED TO COMPARE WITH R.T.P OXIDES. R.T.ANNEALED OXIDES SHOW EXCELLENT BREAKDOWN FIELD. LEAKAGE CURRENT AND TDDB CHARACTERISTICS. ALSO, CAPACITANCE Of R.T NITRIDED OXIDES ARE SUPERIOR BY 10% TO CONVENTIONAL OXIDES, BUT TDDB CHARACTERISTIC ARE POORER THAN OXIDE FILMS.

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Mine water inrush characteristics based on RQD index of rock mass and multiple types of water channels

  • Jinhai Zhao;Weilong Zhu;Wenbin Sun;Changbao Jiang;Hailong Ma;Hui Yang
    • Geomechanics and Engineering
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    • v.38 no.3
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    • pp.215-229
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    • 2024
  • Because of the various patterns of deep-water inrush and complicated mechanisms, accurately predicting mine water inflows is always a difficult problem for coal mine geologists. In study presented in this paper, the water inrush channels were divided into four basic water diversion structures: aquifer, rock fracture zone, fracture zone and goaf. The fluid flow characteristics in each water-conducting structure were investigated by laboratory tests, and multistructure and multisystem coupling flow analysis models of different water-conducting structures were established to describe the entire water inrush process. Based on the research of the water inrush flow paths, the analysis model of different water inrush space structures was established and applied to the prediction of mine water inrush inflow. The results prove that the conduction sequence of different water-conducting structures and the changing rule of permeability caused by stress changes before and after the peak have important influences on the characteristics of mine water-gushing. Influenced by the differences in geological structure and combined with rock mass RQD and fault conductivity characteristics and other mine exploration data, the prediction of mine water inflow can be realized accurately. Taking the water transmitting path in the multistructure as the research object of water inrush, breaking through the limitation of traditional stratigraphic structure division, the prediction of water inflow and the estimation of potentially flooded area was realized, and water bursting intensity was predicted. It is of great significance in making reasonable emergency plans.

Safety education needs among the dental technology-major college students to prevent injuries in their laboratory classes (치기공과 학생들의 실습 중 안전에 대한 안전교육 요구도 특성)

  • Park, Jong-Hee
    • Journal of Technologic Dentistry
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    • v.28 no.1
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    • pp.177-198
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    • 2006
  • This study purposed to offer basic data for safety education of the dental laboratory technology after the investigation of how much the students in the dept. of dental laboratory technology are aware of the danger of each instrument, equipment or laboratory procedure that they use during laboratory and how much they demand safety education for this. The objects for this study were 423 students who were in the dept. of dental laboratory technology. In this regard, four colleges which have the dept. of dental laboratory technology were randomly selected to do a questionnaire survey. SPSS 12.0 was used to analyze the collected data. The results were as follows: As for satisfaction with their major, the respondents answered Satisfied (59.1%), Average (35.5%) and Dissatisfied (5.4%). In terms of the production process of a partial denture, they considered casting, polishing the casting body, polishing denture and burn out were most dangerous in order. As for the production process of a full denture, what they regarded as the most dangerous in order was polishing denture, deflasking and wax wash. Regarding the laboratory procedures of porcelain material, casting, trimming casting body, polishing porcelain material and burn out were the most dangerous procedures that they perceived. With regard to materials for use, alcohol, polishing, metal and wire were the most dangerous ones they thought. As for the handling characteristics of each material, small towns showed a higher demand for safety of the handling characteristics of alcohol. In terms of school year and sex, juniors and girls had higher scores in the demand for safety of the handling characteristics of acid. Regarding the handling characteristics of each equipment and instrument, all of small towns, juniors and girls showed the highest demand for safety of the handling characteristics of alcohol lamps. With regard to scores in the demand for safety of other characteristics, all of small towns, juniors and girls had the highest demand for safety of emergency treatment. Concerning the demand for safety education by the completion of safety education, in terms of each material, highest was the demand for safety of acid from the group which completed safety education. In regard to equipments and instruments, when it came to the demand for safety of the handling characteristics of casting machine, the educated group's demand for safety of acid was higher. Regarding other characteristics, the group which was not educated gained higher scores in the demand for safety of emergency treatment. 11. In all areas(materials, machines and others), small towns, girls and juniors showed higher scores in the demand for safety. Based on the above results, it was found that when students conduct the laboratory of dental technology, they would think that many materials, instruments or equipments for use are very dangerous. However, safety education was not fully given to them. Regarding the scores in the damned for safety education, the highest was 4.16 and the lowest was 3.43, which suggests that the scores were generally very high. In this regard, it is necessary to continue delivering a systematic safety education of materials, equipments or instruments used during the laboratory of dental technology. Therefore, through the analysis of each material, instruments or facility used in every laboratory and each process, safety accident types and accident risk factors should be investigated to develop educational materials for this. Moreover, it is required to open safety education as a single course of study or insert safety contents of all materials and machines into the class of dental laboratory instrument or dental materials for the purpose of a systematic and thorough safety education to prevent a safety accident during laboratory.

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Tuned Optical Reflection Characteristics of Chemically-Treated Ti Substrates

  • Yun, Ho-Gyeong;Kim, Myoung;You, In-Kyu
    • ETRI Journal
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    • v.34 no.6
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    • pp.954-957
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    • 2012
  • Titanium foils for use in photoelectrochemical devices are treated with a $HNO_3$-HF solution. After this treatment, the optical reflection characteristics of the Ti substrates are markedly increased in terms of not only reflectivity but also optimized wavelength. Furthermore, the "multiple beam interference" theory and optical analysis of surface morphologies clearly verify the origin of the optimized optical reflection properties.

Experimental investigation on vortex induced forces of oscillating cylinder at high Reynolds number

  • Xu, Yuwang;Fu, Shixiao;Chen, Ying;Zhong, Qian;Fan, Dixia
    • Ocean Systems Engineering
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    • v.3 no.3
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    • pp.167-180
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    • 2013
  • Hydrodynamic characteristics of a bluff cylinder oscillating along transverse direction in steady flow were experimentally investigated at Reynolds number of $2{\times}10^5$. The effects of non-dimensional frequency, oscillating amplitude and Reynolds number on drag force, lift force and phase angle are studied. Vortex shedding mechanics is applied to explain the experimental results. The results show that explicit similarities exist for hydrodynamic characteristics of an oscillating cylinder in high and low Reynolds number within subcritical regime. Consequently, it is reasonable to utilize the test data at low Reynolds number to predict vortex induced vibration of risers in real sea state when the Reynolds numbers are in the same regime.

Effects of ZnS Insertion on the Characteristics of CaS:Pb Thin Film Phosphor

  • Park, Sang-Hee Ko;Kang, Seung-Youl;Kim, Kwang-Bok;Kim, Dong-Il;Yun, Sun-Jin
    • 한국정보디스플레이학회:학술대회논문집
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    • 2003.07a
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    • pp.1071-1074
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    • 2003
  • The effects of ZnS insertion on the characteristics of CaS:Pb phosphor were investigated. The intensity of photoluminescence of ZnS inserted CaS:Pb excited by 347nm were increased while that excited by 254nm was unchanged, compared to those of CaS:Pb thin film. The electroluminescent display having ZnS inserted CaS:Pb showed lower threshold voltage and higher efficiency than those of CaS:Pb ELD device.

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Controlled synthesis of mesoporous codoped titania nanoparticles and their photocatalytic activity

  • Mathis, John E.;Kidder, Michelle K.;Li, Yunchao;Zhang, Jinshui;Paranthaman, M.P.
    • Advances in nano research
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    • v.4 no.3
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    • pp.157-165
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    • 2016
  • The photocatalytic (PC) activity of anatase titania nanoparticles can be improved through codoping with transition metals and nitrogen. In addition, the PC activity can also be improved by creating monodisperse, mesoporous nanoparticles of titania. The question naturally arose as to whether combining these two characteristics would result in further improvement in the PC activity or not. Herein, we describe the synthesis and photocatalytic characteristics of codoped, monodisperse anatase titania. The transition metals tested in the polydisperse and the monodisperse forms were Mn, Co, Ni, and Cu. In each case, it was found that the monodisperse version had a higher PC activity compared to the corresponding polydisperse version.