• Title/Summary/Keyword: reduced pressure

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A Study on Landfill Leachate Treatment by Reduced Pressure Evaporation. (감압증발법을 이용한 매립장 침출수 처리에 관한 연구)

  • 문추연;은종극;이태호
    • Journal of environmental and Sanitary engineering
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    • v.12 no.3
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    • pp.73-79
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    • 1997
  • This research was intended as an investigation of applying Reduced Pressure Evaporation as efficient treatment method for landfill leachate. According to the variance of time, temperature, pressure and pH in experiments, the properties of leachate treatment are follows. The removal efficiencies of COD, NH$_{3}$-N, TOC, Conductivity and SS on the basis of reaction time was 96.4%-97.5%, -1.4%-53.7%, 81.7%-89.0%, 92.0%-95.3% and 99.86%-99.97%, respectively. When the pH of Influent was 7.5, the pH of effluent was increased to 10-11 with time elapse. It is concluded that the orgin of pH increase may be ammonia. When the properties of concentrate were investigated at the concentration ratio 90%(V/V), concentration difficiency represented in the ratio of experimental value/calculated value had following orders ; COD>TOC>NH$_{3}$-N>Conductivity>SS. Concentrate had good precipitation because of additive thermal treatment in the process. When evaporation experiments with pH adjustment of 4.0, 6.0, 7.5, 9.0 and 10.0 were performed ; Acidic evaporation experiments(pH 4.0, 6.0) showed low removal efficiency(81.6, 87.6%) of COD and high removal efficiency (97.5%. 84.6%) of NH$_{3}$-N at initial evaporation. Basic evaporation(pH 9.0, 10.0) showed high removal efficiency (97.2%, 98.9%) of COD and very low removal efficiency (-7.4%, -27.2%) of NH$_{3}$-N at initial evaporation.

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Effects of Vacuum Hot Pressing Conditions on Mechanical Properties and Microstructures of $SiC_w$/2124Al Metal Matrix Composites (Vacuum Hot Pressing 조건이 $SiC_w$/2124AI 금속복합재료의 기계적 성질 및 미세구조에 미치는 영향)

  • 홍순형
    • Journal of Powder Materials
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    • v.1 no.2
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    • pp.159-166
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    • 1994
  • The variation of the microstructures and the mechanical properties with varying vacuum hot pressing temperature and pressure was investigated in PyM processed 20 vol%) SiCw/ 2124Al composites. As increasing the vacuum hot pressing temperature, the aspect ratio of whiskers and density of composites increased due to the softening of 2124Al matrix with the increased amount of liquid phase. The tensile strength of composite increased with increasing vacuum hot pressing temperature up to $570^{\circ}C$ and became saturated above $570^{\circ}C$, To attain the high densification of composites above 99%, the vacuum hot pressing pressure was needed to be above 70 MPa. However, the higher vacuum hot pressing pressure above 70 MPa was not effective to increase the tensile strength due to the reduced aspect ratio of SiC whiskers from damage of whiskers during vacuum hot pressing. A phenomenological equation to predict the tensile strength of $SiC_w$/2124AI composite was proposed as a function including two microstructural parameters, i.e. density of composites and aspect ratio of whiskers. The tensile strength of $SiC_w$/2124AI were found more sensitive to the porosity than other P/M materials due to the higher stress concentration and reduced load transfer efficiency by the pores locating at whisker/matrix interfaces.

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Brown Rice Phytosterol Improves Hypertension and Lipid Metabolism in Spontaneously Hypertensive Rats (본태성 고혈압쥐(SHR)에서 현미 식물성스테롤의 혈압 및 지질 대사 개선 효과)

  • Hong, Kyung Hee;Kim, In-Hwan;Choue, Eun Kyung;Ahn, Jiyun;Ha, Tae Youl
    • Journal of the Korean Society of Food Culture
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    • v.27 no.5
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    • pp.535-543
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    • 2012
  • This study was conducted to investigate the effects of brown rice and brown rice phytosterol on blood pressure and lipid levels in spontaneously hypertension rats (SHR). SHR were grouped according to blood pressure and fed either a control diet or experimental diets containing 50% brown rice powder or 5% brown rice phytosterol for 3 weeks. Body weight gain and epididymal fat weight were significantly reduced in the brown rice powder and brown rice phytosterol groups compared to control. Brown rice and brown rice phytosterol diets suppressed age-dependent increases in systolic blood pressure compared to control. In addition, brown rice and brown rice phytosterol diets decreased total lipid, triglyceride, and cholesterol levels in the liver, whereas serum HDL cholesterol increased. Lastly, brown rice phytosterol reduced TBARS contents in the kidney. These results suggest that brown rice and brown rice phytosterol exert antihypertensive effects that improve lipid metabolism in SHR.

Pool Boiling Heat Transfer Coefficients of New Refrigerants on Various Enhanced Tubes (열전달 촉진관에서 신냉매의 풀비등 열전달계수)

  • 박진석;김종곤;정동수;김영일
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.13 no.8
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    • pp.710-719
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    • 2001
  • Pool boiling heat transfer coefficients (HTCs) of HCFC123, HFC134a, HCFC22, HFC407C, HFC410A and HFC32 wre measured on a horizontal smooth tube, 26 fpi low fin tube, Turbo-B and Thermoexcel-E enhanced tubes. AN experimental apparatus was designed such that all tubes heated by cartridge heaters could be installed at the same time to save the refrigerant. Data were taken in the pool of $7^{\circ}C$ with the heat flux decreasing from 80 kW/$m^2\;to\;5kW/m^2$. Test results showed that HTCs of pure refrigerants and those of a azeotrope were greatly influenced by reduced pressure. HTCs of HFC407C were 21~25% lower than those of HCFC22 due to mass transfer resistance. For all refrigerants, enhanced tubes with sub-surface and sub-tunnels showed the largest heat transfer enhancement. Especially the largest heat enhancement was obtained for HCFC123 whose reduced pressure is the lowest among al the refrigerants tested. This indicates that either Turbo-B or Thermoexcel-E enhanced tube would be the best choice when used with a low vapor pressure refrigerant.

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The Characteristics of Diurnal Changes in the Tissue-Water Relations of Pueraria thunbergiana (칡(Pueraria thunbergiana) 조직수분관계의 일변화 특성)

  • 박용목;최창렬
    • The Korean Journal of Ecology
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    • v.21 no.1
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    • pp.89-96
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    • 1998
  • The diurnal changes of the stomatal conductance, transpiration and leaf water potential were measured in order to assess the water relations characteristics of Pueraria thunbergiana in August of 1995 and 1996. The results showed two different responses depending on the duration of rainless days. The microclimatic conditions were highly stressful on 2 August. Daily maximum temperature reached to $39.0{\circ}C$ and vapor pressure deficit was 3.55 KPa. During this time the leaf water potential decreased to -1.02 MPa and a marked reduction of stomatal conductance was shown. However, on 15 August the stomatal conductance increased with increment of photon flux density, and transpiration was highly maintained during the day time. Minimum leaf water potential was only -0.47 MPa in spite of high transpiration rate. Furthermore, on 15 August reduced leaf water potential during the day time was recovered rapidly with decrease of photon flux density, whereas recovery of leaf water potential on 2 August was delayed. However, reduced leaf water potential on 2 August was recovered untile the next dawn. Osmotic potential at turgor loss point of Pueraria thunbergiana on 2, 3 and 15 August was -1.79, -1.70 and -1.60 MPa, respectively. The vapor pressure deficit is more contributive to the regulation of stomatal conductance than leaf water potential.

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Effects of Discrete Ribs on Pressure Drop in a Rotating Two-Pass Duct (단락요철이 회전덕트 내 압력강하에 미치는 영향)

  • Kim Kyung-Min;Lee Dong-Hyun;Cho Hyung-Hee
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.18 no.5
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    • pp.443-450
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    • 2006
  • The present study has been conducted to investigate the effects of rotation on heat/mass transfer and pressure drop characteristics in a two-pass square duct with and without discrete ribs. For stationary cases, the heat/mass transfer on the surfaces with and without discrete ribs is almost the same or reduced. For rotating cases, the gap flow affects differently the heat/mass transfer on leading and trailing surfaces with discrete ribs. On the leading surface of the first pass, the heat/mass transfer is slightly enhanced due to generating strong gap flow. On the trailing surface of the first pass, however, the heat/mass transfer is much decreased because the gap flow disturbs impingement of main flow. The phenomenon, that is, the heat/mass transfer discrepancy between the leading and trailing surfaces is distinctly presented with the increment of rotation number. The friction losses on each surface with discrete ribs are reduced because the blockage ratio decreases for both non-rotating and rotating cases. Therefore, high thermal performance appears in a duct with discrete ribs.

Assessment of the Influence of Application Time of Lidocaine Patch on Pain Intensity after Venipuncture (정맥천자 시 리도카인 패치의 적용시간에 따른 통증경감 효과)

  • No, In Sun;Kim, Se Young
    • Journal of Korean Academy of Fundamentals of Nursing
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    • v.25 no.4
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    • pp.250-258
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    • 2018
  • Purpose: This study was done to assess the influence of application time of Lidocaine patch on pain intensity following venipuncture in hospital. Methods: The participants were 31 adult patients admitted to J hospital in G city. Patients' anxiety, blood pressure and pulse were measured when no patch was applied and when a patch was applied. To evaluate the pain intensity and physiological index caused by venipuncture, blood pressure, pulse and pain intensity were checked for patients in the no patch group, and for a 5 minutes of application and 30 minutes application patch. Pain was evaluated using a visual analogue scale, anxiety using the Profile of Mood states developed McNair et al. and modified by Lee. Data were analyzed using one-way repeated measures ANOVA with the SPSS 21.0 program. Results: Anxiety and pain were significantly reduced when a lidocaine patch was applied following venipuncture. There was no significant difference in pain intensity whether the lidocaine patch application is for 30 minutes or application for 5 minutes. Conclusion: Results of this study show that application of lidocaine patch can be used as a nursing intervention for pain reduction by showing that there is no need to wait a long time for pain to be reduced.

A Study on the Minimum Ignition Energy Measurements for Liquid Jet A1 Fuel under at Elevated Oxygen Concentrations and Reduced Atmospheric Pressures (고산소-저기압 환경에서 JET A1 액체연료의 최소점화에너지 측정에 관한 연구)

  • Kwon, Haeng-Jun;Park, Seul-Hyun
    • Journal of the Korean Society of Manufacturing Process Engineers
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    • v.16 no.3
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    • pp.88-93
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    • 2017
  • In the present study, the ignition characteristics of liquid fuel were experimentally investigated. To quantify its ignitability as ignition characteristics, the minimum ignition energy (MIE) of liquid fuel was defined and measured under at the elevated oxygen concentrations and reduced atmospheric pressures which that are the most probable conditions likely to be encountered during operation of the space launch vehicle's operating process. The experimental results demonstrate that the measured MIE decreased with the increasing the oxygen concentration at given atmospheric pressures. When the atmospheric pressure was reduced from 1 atm to 0.2 atm at a fixed oxygen concentration, the measured MIE was found to vary with $P^{-2}$ but the lowest MIE was observed at 0.8 atm.

Buckling Analysis of Pipelines with Reduced Cross Section (단면감소를 고려한 파이프의 좌굴에 관한 연구)

  • Choi, Dong-Ho;Ko, Young-Chan;Gwon, Sun-Gil;Lee, Joung-Sun
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.33 no.3
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    • pp.865-873
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    • 2013
  • This paper proposes a theoretical solution of elastic critical buckling load of infinitely long pipelines with non-uniform thickness under external pressure. The non-uniform cross section of pipelines can be considered as corroded or stiffened pipelines so that this paper can be a fundamental research of pipelines that are essential technology for offshore industries. The theoretical solution of pipelines with non-uniform thickness is derived with an assumption that a cylindrical shell under external pressure can be considered as a simple ring. The eigenfunctions are derived to obtain the critical buckling load. The reduced thickness and the reduced range are considered as variables in parametric analysis. The finite element analysis is performed to verify the theoretical solutions and the results of the analytic method and the finite element method are in good agreement.

Comparison of Injection Molding Characteristics according to Thickness Variations of Preform for PET bottle

  • Kim, Nam Hyun;Woo, In Young;Nam, Kyung Woo;Yeon, Baek Rim;Kim, Mi Rae;Lyu, Min-Young
    • Elastomers and Composites
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    • v.56 no.3
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    • pp.164-171
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    • 2021
  • Due to the problem of environmental pollution by plastics, it is necessary to decrease their consumption. In the case of PET bottles, it is essential to reduce the thickness of the bottle for the reduction of plastic used. For manufacturing PET bottles with reduced thickness, it is a prerequisite to design a preform with reduced thickness and study its molding capability. In this study, the injection molding capability was investigated after reducing the body thickness of the preform to 15% and 20%, respectively, for the two preform models currently in use. Injection molding analysis was performed on the existing models and on the models for reduced weight, under the molding conditions of the existing models. Using the computed results, temperature distribution, pressure distribution, deformation and clamping force were compared. Based on the analysis, the injection conditions of the preform model with less thickness were discussed.