• Title/Summary/Keyword: Chamber experiment

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Effect of Silica Gel on Food Dehydration of Onion by Solar Energy (태양열(太陽熱)을 이용(利用)한 식품건조(食品乾燥)에서 Silica Gel의 활용효과(活用效果))

  • Jeon, Byeong Seon;Yoon, Han Kyo;Chang, Kyu Seob
    • Korean Journal of Agricultural Science
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    • v.10 no.1
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    • pp.156-165
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    • 1983
  • This experiment was carried out to elucidate the drying characteristics of onion and dehumidifying effect of air using the silica gel and to reuse it by solar collector. The results were summarized as follows. 1. It takes 14hours to regenerate to silica gel of 8% moisture content from saturated silica gel in conditions of $28^{\circ}c$ temperature and 55% relative humidity. 2. When sample was recycled through solar collector, the result of drying was 1/2 times more efficient than that of mat drying. 3. Average thermal efficiency of solar collector was 25% during the experimental period. 4. Browning extent was reduced to 1/2 times at heated air blow drying system using drying chamber.

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Formation of Ultra fine Particle by the Polonium-218 Ions under Different Humidity Conditions (다른 습도조건하에서 Po-218 이온들의 극소입자형성에 관한 연구)

  • Yoon, Suk-Chul;Ha, Chung-Woo
    • Journal of Radiation Protection and Research
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    • v.17 no.1
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    • pp.1-10
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    • 1992
  • A number of investigators have reported the formation of the radiolytic ultrafine particles produced by the interaction of ionizing radiation with water vapor. Previous studies have suggested that a very high localized concentration of the OH radical produced by the radiolysis of water can react with trace gas like organic vapors and produce lower vapor pressure compounds that can then nucleate. In order to determine water vapor dependence of the active, positively charged, first radon daughter(Po-218), an experiment was conducted using a well-controlled radon chamber. The activity size distribution of the radon daughter in the range of 0.5-100nm was measured using the parallel graded wire screens system. Measurements were taken for different relative humidity. The resultant activity size distributions were analyzed. The addition of water vapor to the radon carrier gases resulted in the formation of ultrafine particles by OH radicals formed by radon radiolysis. It may be due to the neutralization of charged Po-218 ion with water vapor through the radio lysis.

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Experimental Study on Smoke Production and Smoke Generation in Thermoplastic Resins Based on PP, PMMA, and PVC (열가소성 수지(PP, PMMA, PVC)의 연기생성 및 발생에 관한 실험적 연구)

  • Hwang, Euy-Hong;Choi, Don-Mook
    • Fire Science and Engineering
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    • v.34 no.3
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    • pp.1-7
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    • 2020
  • Due to the complexity and large size of buildings, plastic resin is widely used as a building material. Accordingly, the occurrence of fires caused by plastics is increasing. Due to the nature of plastic resin fires, the amount of damage to properties and human life caused by combustion products such as smoke are large, and these damages are related to smoke production and smoke generation. Therefore, this study reviews smoke measurement methods and laws on domestic buildings and fire services. Experiments were conducted based on three smoke-related test standards (ISO 5660-1, ISO 12136, ASTM E 662). The experiment results indicate a total smoke production and generation by PP, PVC, and PMMA of 43.27, 32.83, and 12.33 ㎡, and 27.855, 9.599, and 6.975 g, respectively.

Numerical Analysis of Reflection Characteristics of Perforated Breakwater with a Resonant Channel (공진수로 내장형 유공방파제의 반사특성에 관한 수치해석 연구)

  • Kim, Jeong-Seok;Seo, Ji-Hye;Lee, Joong-Woo;Park, Woo-Sun
    • Journal of Navigation and Port Research
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    • v.38 no.5
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    • pp.503-509
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    • 2014
  • In this study, a new concept perforated breakwater is proposed, which is having resonant channels. In the channel, perforated plate is installed for dissipating wave energy induced by flow separations. The breakwater has two advantages compared with conventional perforated breakwater having wave chamber with slotted walls. One is easy to control the target wave condition for dissipating wave energy, and the other is having the high structural safety because the structural members are not exposed to impact waves, directly. To evaluate wave reflection characteristics of the proposed breakwater, numerical experiment was carried out by using Galerkin's finite element model based on the linear potential theory. The results indicated that considerable energy dissipation occurs near the resonant period of channel, and wave reflection characteristics are affected by channel shape, location and opening ratio.

POLYMER SURFACE MODIFICATION WITH PLASMA SOURCE ION IMPLANTATION TECHNIQUE

  • Han, Seung-Hee;Lee, Yeon-Hee;Lee, Jung-Hye;Yoon, Jung-Hyeon;Kim, Hai-Dong;Kim, Gon-ho;Kim, GunWoo
    • Journal of Surface Science and Engineering
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    • v.29 no.5
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    • pp.345-349
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    • 1996
  • The wetting property of polymer surfaces is very important for practical applications. Plasma source ion implantation technique was used to improve the wetting properties of polymer surfaces. Poly(ethylene terephtalate) and other polymer sheets were mounted on the target stage and an RF plasma was generated by means of an antenna located inside the vacuum chamber. High voltage pulses of up to -10kV, 10 $\mu$sec, and up to 1 kHz were applied to the stage. The samples were implanted for 5 minutes with using Ar, $N_2,O_2,CH_4,CF_4$ and their mixture as source gases. A contact angle meter was used to measure the water contact angles of the implanted samples and of the samples stored in ambient conditions after implantation. The modified surfaces were analysed with Time-Of-Flight Mass Spectrometer (TOF-SIMS) and Auger Electron Spectroscopy (AES). The oxygen-implanted samples showed extremely low water contact angles of $3^{\circ}C$ compared to $79^{\circ}C$ of unimplanted ones. Furthermore, the modified surfaces were relatively stable with respect to aging in ambient conditions, which is one of the major concerns of the other surface treatment techniques. From TOF-SIMS analysis it was found that oxygen-containing functional groups had been formed on the implanted surfaces. On the other hand, the $CF_4$-implanted samples turned out to be more hydro-phobic than unimplanted ones, giving water contact angles exceeding $100^{\circ}C$ . The experiment showed that plasma source ion implantation is a very promising technique for polymer surface modification especially for large area treatment.

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THE EFFECT OF ADDITIONAL ENAMEL ETCHING ON MICROLEAKAGE OF THE ADHESION OF SELF-ETCHING PRIMER SYSTEM (자가 산부식 프라이머 시스템 사용시 인산에 의한 부가적인 산부식이 미세누출에 미치는 영향)

  • Yoon, Jung-Jin;Min, Kyung-San;Hong, Chan-Ui
    • Restorative Dentistry and Endodontics
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    • v.28 no.5
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    • pp.363-368
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    • 2003
  • The purpose of this study is to evaluate the effect of additional enamel etching with phosphoric acid on the microleakage of the adhesion of self-etching primer system. Class V cavity($4mm{\times}3mm{\times}1.5mm$) preparations with all margins in enamel were prepared on buccal surface of 42 extracted human upper central incisor teeth. Prepared teeth were randomly divided into 3 groups. Group 1:no additional pretreatment with 37% phosphoric acid (NE). Group 2:additional pretreatment with 37% phosphoric acid for 10 seconds (E10s). Group 3:additional pretreatment with 37% phosphoric acid for 20 seconds (E20s). The adhesives(Clearfil SE $Bond^{\circledR}$, Kuraray, Osaka, Japan) and composite resins(Clearfil $AP-X^{\circledR}$, Osaka, Kuraray, Japan) were applied following the manufacturer's instructions. All the specimens were finished with the polishing disc(3M dental product, St Paul, MN, USA), thermocycled for 500 cycles between $5^{\circ}C$ and $55^{\circ}C$ and resected apical 3-mm root. 0.028 stainless steel wire was inserted apically into the pulp chamber of each tooth and sealed into position with sticky wax. Surrounding tooth surface was covered with a nail varnish 2 times except areas 1mm far from all the margins. After drying for one day, soaked the samples in the distilled water. Microleakage was assessed by electrochemical method(System 6514, $Electrometer^{\circledR}$), Keithley, USA) in the distilled water. In this study, the microleakage was the lowest in group 1 (NE) and the highest in group 3(E20s)(NE

Long-Term Tropical Residency Diminishes Central Sudomotor Sensitivities in Male Subjects

  • Lee, Jeong-Beom;Bae, Jun-Sang;Shin, Young-Oh;Kang, Jong-Chul;Matsumoto, Takaaki;Toktasynovna, Aliopva Aziza;Kaimovich, Alipov Gabit;Kim, Wan-Jong;Min, Young-Ki;Yang, Hun-Mo
    • The Korean Journal of Physiology and Pharmacology
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    • v.11 no.6
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    • pp.233-237
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    • 2007
  • Tropical natives (TROP) are capable of tolerating tropical heat because of their long-term adaptation to tropical environments. When exposed to heat stress, these natives tend to respond with lower sweat output, which is generally thought to be the result of heat acclimatization. The main objective of this study was to clarify central mechanisms inherent to suppressed thermal sweating in tropical natives (Malaysians) by comparing their sweating responses to those of temperate native (TEMP) (Koreans). This experiment was conducted in a thermoneutral climatic chamber ($24{\pm}0.5^{\circ}C,\;40{\pm}3%$ relative humidity). Heat loads were applied to each subject by the immersion of their lower legs in a hot water bath ($43^{\circ}C$ for 30 min). Sweat onset-time and sweat volume were compared between TROP and TEMP. The sweat onset-times on four selected points on the body ranged from 10.25 to 13.47 min in TEMP subjects, and from 16.24 to 17.83 min in TROP subjects (p<0.001). The local sweat volumes at the same sites ranged from 4.30 to $9.74 mg/cm^2$ in TEMP subjects, and from between 1.80 to $4.40mg/cm^2$ in TROP subjects (p<0.001). These results demonstrated a significant difference between TROP and TEMP subjects with regard to the manner in which they regulate their body temperatures when exposed to heat loads, and verified that long-term thermal adaptation blunts sweating sensitivities.

Measurement of electron temperature and density using Stark broadening of the coaxial focused plasma for extreme ultraviolet (EUV) lithography

  • Lee, Sung-Hee;Hong, Young-June;Choi, Eun-Ha
    • Proceedings of the Korean Vacuum Society Conference
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    • 2010.02a
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    • pp.475-475
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    • 2010
  • We have generated Ar plasma in dense plasma focus device with coaxial electrodes for extreme ultraviolet (EUV) lithography and investigated an emitted visible light for electro-optical plasma diagnostics. We have applied an input voltage 4.5 kV to the capacitor bank of 1.53 uF and the diode chamber has been filled with Ar gas of pressure 8 mTorr. The inner surface of the cylindrical cathode has been attatched by an acetal insulator. Also, the anode made of tin metal. If we assumed that the focused plasma regions satisfy the local thermodynamic equilibrium (LTE) conditions, the electron temperature and density of the coaxial plasma focus could be obtained by Stark broadening of optical emission spectroscopy (OES). The Lorentzian profile for emission lines of Ar I of 426.629 nm and Ar II of 487.99 nm were measured with a visible monochromator. And the electron density has been estimated by FWHM (Full Width Half Maximum) of its profile. To find the exact value of FWHM, we observed the instrument line broadening of the monochromator with a Hg-Ar reference lamp. The electron temperature has been calculated using the two relative electron density ratios of the Stark profiles. In case of electron density, it has been observed by the Stark broadening method. This experiment result shows the temporal behavior of the electron temperature and density characteristics for the focused plasma. The EUV emission signal whose wavelength is about 6 ~ 16 nm has been detected by using a photo-detector (AXUV-100 Zr/C, IRD). The result compared the electron temperature and density with the temporal EUV signal. The electron density and temperature were observed to be $10^{16}\;cm^{-3}$ and 20 ~ 30 eV, respectively.

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A study on the heat transfer characteristics of swirling flow in a circular sectioned $180^{\circ}C$bend with uniform heat flux (균일 열플럭스가 있는 $180^{\circ}C$ 원형단면 곡관의 선회유동 열전달특성 연구)

  • Lee, Sang-Bae;Gwon, Gi-Rin;Jang, Tae-Hyeon
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.21 no.5
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    • pp.615-627
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    • 1997
  • An experiment was performed to local heat transfer coefficient and Nusselt number in the circular duct of 180.deg. bend for Re=6*10$^{4}$, 8*10$^{4}$ and 1*10$^{5}$ at swirling flow and non-swirling flow conditions. The test tube with circular section was made by stainless which has curvature ratio 9.4. The wall of test tube was heated directly by electrical power to 3.51 kw and swirling motion of air was produced by a tangential inlet to the pipe axis at the 180 degree. Measurements of local wall temperatures and bulk mean temperature of air are made at four circumferential positions in the 16 stations. The wall temperatures show particularly reduced distribution curve at bend for non-swirling flow but this effect does not appear for swirling flow. Nusselt number distributions for swirling flow which was calculated from the measured wall and bulk temperatures were higher than that of non-swirling flow. Average Nusselt number of swirling flow increased about 90 ~ 100% than that of non-swirling flow whole through the test tube. The Nu/N $u_{DB}$ values at the station of 90.deg. for non-swirling flow and swirling flow are respectively about 2.5 and 4.8 at Re=6*10$^{4}$. Also that is good agreement with Said's result for non-swirling flow. flow.

Enhancement of Health Functional Compounds in the Sprouts of Barley (Hordeum vulgare L.) Cultivars by UV-B and Salicylic Acid Treatments

  • Kim, Yong-Hyun;Kim, Seong-Min;Cheng, Hyo-Cheng;Lee, Young-Woo;Shim, Ie-Sung
    • Horticultural Science & Technology
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    • v.29 no.1
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    • pp.61-67
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    • 2011
  • Barley (Hordeum vulgare L.) sprouts are a vegetable commonly used as a functional food material due to its high vitamin C concentration and antioxidant activity. In this experiment, we measured the changes in the antioxidant activity of several barley cultivars as well as in the concentrations of related compounds such as ascorbate and glutathione upon treatment with UV-B or salicylic acid (SA). The six barely cultivars were grown in a plant growth chamber (25/$18^{\circ}C$, 14/10 h, 200 ${\mu}mol{\cdot}m^{-1}{\cdot}s^{-1}$, 70% relative humidity) for 10 days. All barely cultivars showed different 1, 1-diphenyl-2-picryl-hydrazyl (DPPH) scavenging activities, which were increased by UV-B treatment and not by SA treatment. The changes in ascorbate concentrations were correlated with DPPH scavenging activity in both the treatments, suggesting that the antioxidant activity in barley sprouts was mainly dependent on ascorbate concentration. Furthermore, changes in ascorbate concentration showed similar tendencies to changes in free sugar concentration, especially glucose and sucrose, in both treatments. On the other hand, the concentrations of glutathione and cysteine highly increased by SA treatment, representing different tendencies compared to the DPPH scavenging activity and ascorbate concentration. 'Donghanchal' cultivar showed comparatively higher antioxidant activity, both constitutively and inducingly by UV-B treatment, with its higher concentrations of ascorbate and glutathione. These results suggest that barley sprouts could be used as a health-functional vegetable, contributing to the overall supply of antioxidant and sulfur-containing organic compounds.