• Title/Summary/Keyword: Concentration Characteristics

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The CO Gas Concentration Characteristics in a Sound Proof Road Tunnel According to the Upper Opening Installation Distance Interval (방음터널 내부의 상부배출구 간격에 따른 CO 농도분포 특성)

  • Park, Myung Sig
    • Journal of ILASS-Korea
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    • v.21 no.3
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    • pp.162-169
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    • 2016
  • When we construct a road near an apartment complex, we consider a soundproof wall. To make residential places quieter, we may consider a soundproof road tunnel. Such a tunnel, however, would become highly concentrated with soot from vehicles whenever a traffic jam might occur. To create an optimum design, this study utilizes the PHOENICS-VR software. The work considers three cases: (1) no openings (2) openings at 30m intervals, and (3) openings at 60m intervals on the upper side of the tunnel. The study finds that in the second case shows CO concentration distributions were 15% less than those without openings. And the CO concentration distributions of the second and third cases are almost the same. The findings suggest that we should make the soundproof tunnel to reduce construction fees.

Characteristics of AC Hot-carrier-induced Degradation in nMOS with NO-based Gate Dielectrics (NO기반 게이트절연막 NMOS의 AC Hot Carrier 특성)

  • Chang, Sung-Keun;Kim, Youn-Jang
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.17 no.6
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    • pp.586-591
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    • 2004
  • We studied the dependence of hot-tarrier-induced degradation characteristics on nitrogen concentration in NO(Nitrided-Oxide) gate of nMOS, under ac and dc stresses. The $\Delta$V$_{t}$ and $\Delta$G$_{m}$ dependence of nitrogen concentration were observed, We observed that device degradation was suppressed significantly when the nitrogen concentration in the gate was increased. Compared to $N_2$O oxynitride, NO oxynitride gate devices show a smaller sensitivity to ac stress frequency. Results suggest that the improved at-hot carrier immunity of the device with NO gate may be due to the significantly suppressed interface state generation and neutral trap generation during stress.ess.

A study on the Management of Non-point Source Using Peak Water Quality Concentration (첨두수질농도를 이용한 비점오염원 관리방안 연구)

  • Kal, Byungseok;Park, Jaebeom;Kwon, Heongak;Im, Taehyo;Lee, Jiho
    • Journal of Wetlands Research
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    • v.19 no.3
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    • pp.287-295
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    • 2017
  • In this study, rainfall runoff characteristics according to peak concentration were analyzed using the water quality and flow data in the Geumho river, and the direction of nonpoint source management such as monitoring and management period by pollution source was derived. Peak Water Quality Concentration is the concept that utilizes the extreme value as the concentration of non-point pollution control standard with the highest water quality in the rainwater runoff. Using this method, the evaluation factors such as cumulative precipitation(total precipitation), peak water quality concentration, cumulative precipitation up to peak water quality concentration, time to peak water quality concentration, and EMC to peak water quality concentration were examined and long- Rainfall runoff characteristics of nonpoint sources were analyzed. The results of the analysis suggested proper monitoring and management method to manage nonpoint source.

Adsorption and Desorption Characteristics of Carbon Dioxide at Low Concentration on Zeolite 5A and 13X (제올라이트 5A와 13X의 저농도 이산화탄소 흡착 및 탈착특성)

  • Cho, Young-Min;Lee, Ji-Yun;Kwon, Soon-Bark;Park, Duck-Shin;Choi, Jin-Sik;Lee, Ju-Yeol
    • Journal of Korean Society for Atmospheric Environment
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    • v.27 no.2
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    • pp.191-200
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    • 2011
  • A way to adsorptively remove indoor carbon dioxide at relatively lower concentration under ambient temperature was studied. A small lab-scale carbon dioxide adsorption and desorption reactors were prepared, and 5A and 13X zeolites were packed in this reactors to investigate their adsorption and desorption characteristics. The inflow carbon dioxide concentration was controlled to 5,000 ppm, relatively higher concentration found in indoor spaces with air quality problems, by diluting carbon dioxide with nitrogen gas. The flow rate was varied as 1~5 L/min, and the carbon dioxide concentration after this reactor was constantly monitored to examine the adsorption characteristics. It was found that 5A adsorbed more carbon dioxide than 13X. A lab-scale carbon dioxide desorption reactor was also prepared to investigate the desorption characteristics of zeolites, which is essential for the regeneration of used zeolites. The desorption temperature was varied as $25{\sim}200^{\circ}C$, and the desorption pressure was varied as 0.1~1.0 bar. Carbon dioxide desorbed better at higher temperature, and lower pressure. 5A could be regenerated more than three times by thermal desorption at $180^{\circ}C$. It is required to modify zeolites for higher adsorption and better regeneration performances.

A Study on Characteristics of NOx and Ozone by Plasma Reaction (Plasma반응에 의한 NOx와 Ozone의 특성에 관한 연구)

  • Choi Jae Wook;Yamaguma Mizuki;Choi Jae Jin
    • Journal of the Korean Institute of Gas
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    • v.4 no.2 s.10
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    • pp.1-6
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    • 2000
  • In this experiment, we made the plasma reactor which adhere needle electrode in order to treat safely an NOx which was included in the gas. Also we experimently investigated characteristics of equipment and inspected efficiency. As a reaction gas, by using mixture gas of $NO/N_2$ and $N_2/O_2$, we setted up initial NO concentration and gas flow rate was set at 2 ${\iota}$/min. As a reaction characteristics of NOx, when discharge input power was high, NO concentration decreased and when the oxygen concentration increased, the NO decomposition was easy and decomposition energy efficiency was high. Also in case that NO concentration increased, NO decomposition energy efficiency was high but decomposition rate was low. The characteristics of ozone, when discharge input power was high, ozone increased and when $NO/N_2$ concentration increased, the ozone decreased.

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Concentration Characteristics of Indoor and Outdoor Airborne Total Fiber Particles and Identification of Asbestos in Gyeongnam Provinces (경남지역의 실내외 공기 중 총섬유 입자의 농도특성 및 석면 입자의 확인)

  • Park, Hee-Eun;Park, Jeong-Ho;Kim, Hyoung-Kab
    • Journal of Korean Society of Occupational and Environmental Hygiene
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    • v.22 no.2
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    • pp.119-127
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    • 2012
  • Objectives: The aim of this study is to identify concentration characteristics of indoor and outdoor airborne total fiber particles and asbestos in Gyeongnam Provinces. Methods: This study investigated concentration characteristics of indoor fiber particles from 748 schools and 38 public facilities as well as outdoor particles from 11 sites through PCM (phase contrast microscope). SEM/EDX (scanning electron microscope/energy dispersive using X-ray analysis) was used to obtain physicochemical information of asbestos fiber particles. The study identified asbestos rate in the 15 samples from indoor and outdoor airborne total fiber particles. Results: 1. The average indoor airborne concentrations of total fiber particles were $0.0011{\pm}0007$ f/cc in schools and $0.0015{\pm}0007$ f/cc in public facilities by PCM. Over 90% of the fiber particles were identified as single fibers. 2. The average outdoor airborne concentrations of total fiber particles were $0.0007{\pm}0002$ f/cc, and they were lower than those of indoor airborne concentrations. 3. The results showed that the form of asbestiform was diverse as skein of thread like form and long needle, which was relatively narrower than that of glass fiber and rock wool. 4. The results of SEM/EDX analysis of 15 areas where total fiber particle was relatively high showed that the form was rather similar to that of asbestos, but chemical composition was proven to be non-asbestos. Conclusions: The concentration of indoor and outdoor airborne total fiber particles of Gyeongnam Provinces satisfied the IAQ (Indoor air quality) level of 0.01 f/cc and asbestos was not found in most of the samples by SEM/EDX.

Association of Prostate Specific Antigen Concentration with Lifestyle Characteristics in Korean Men

  • Woo, Hee-Yeon;Park, Hyosoon;Kwon, Min-Jung;Chang, Yoosoo;Ryu, Seungho
    • Asian Pacific Journal of Cancer Prevention
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    • v.13 no.11
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    • pp.5695-5699
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    • 2012
  • We investigated the relationships between demographics, lifestyle characteristics, and serum total prostate specific antigen (PSA) concentration and examined the population-based distribution of total PSA by age among 2,246 Korean men with a median age of 45 years. We obtained data about demographic and lifestyle characteristics based on self-reporting using a quetionnaire. We also performed physical examinations, anthropometric measurements, and biochemical measurements. The PSA concentration increased with age and there was a significant difference in total PSA concentration between the age groups of 21-60 years and >60 years. Age >60 years, height ${\geq}1.8$ m, a low frequency of alcohol consumption, and taking nutritional supplements showed a significantly increased odds ratio for increased PSA when 3.0 ng/mL was chosen as the PSA cut-off level. Smoking status, BMI, percent body fat, diabetes mellitus, fatty liver, herbal medicine use, vitamin use, and diet were not significantly associated with total PSA regardless of the cut-off level. When interpreting a single PSA test, height, alcohol consumption, and nutritional supplement use should be considered, in addition to age.

Analysis of Transport Characteristics for DGMOSFET according to Channel Dopiong Concentration Using Series (급수를 이용한 DGMOSFET의 채널도핑농도에 대한 전송 특성 분석)

  • Han, Jihyung;Jung, Hakkee;Jeong, Dongsoo;Lee, Jongin;Kwon, Ohshin
    • Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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    • 2012.10a
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    • pp.845-847
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    • 2012
  • In this paper, the transport characteristics for doping concentration in the channel has been analyzed for DGMOSFET. The Possion equation is used to analytical. The DGMOSFET is extensively been studying because of advantages to be able to reduce the short channel effects(SCEs) to occur in conventional MOSFET. Since SCEs have been occurred in subthreshold region including threshold region, the analysis of transport characteristics in subthreshold region is very important. The threshold voltage roll-off and DIBL have been with various of doping concentration for DGMOSFET in this study.

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Settling Characteristics of Water Treatment Plant Sludges by Pretreatment Methods (정수장슬러지의 전처리에 의한 침전특성)

  • Moon, Yong-taik;Lee, Sun-ju
    • Journal of Korean Society of Water and Wastewater
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    • v.22 no.6
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    • pp.627-632
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    • 2008
  • It is necessary to investigate methods for improvement by diagnosing sludge settling characteristics on inflow of slurry to thickener. The results of the settling tests are correlated to determine zone settling velocities at the various sludge solids concentrations. Conditioning of WTP residuals is generally done by either chemical or physical treatment. The settling test was conducted with 1m columns dosing polymer to WTP residuals at various solids concentration. The estimated results for dosing to WTP residuals for a sludge of 2,100 ~ 16,012 mg/L solids concentration were the zone settling velocities of 48.38 ~ 6.8 m/day, supernatant solid concentration of 3.2 ~ 19 mg/L and solid flux of $101.6{\sim}317.61kg/m^3{\cdot}day$. The values for non-polymer treatment were the zone settling velocities of 28.37 ~ 0.12 m/day, supernatent solid concentration of 8.5 ~ 108 mg/L and solid flux of $59.58{\sim}1.92kg/m^2{\cdot}day$. The limiting solid flux value by Yoshioka methods was $4.0kg\;TS/m^3{\cdot}day$ for Non-polymer and $228.0kg\;TS/m^3{\cdot}day$ for dosing polymer. These results are to indicate a possibility of improvement on the thickening characteristics and the quality of supernatant as increasing the settling velocities by dosing polymer to WTP residuals.

Quality Characteristics of Cookies Added with Guava(Psidium guajava L.) Leaf Powder (구아바 잎 분말을 첨가한 쿠키의 품질 특성)

  • Jeong, Eun-Ja;Kim, Kwan-Pil;Bang, Byung-Ho
    • The Korean Journal of Food And Nutrition
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    • v.25 no.2
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    • pp.317-323
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    • 2012
  • We investigated the quality characteristics of cookies prepared after the addition of various concentration of used guava leaf powder(0%, 1%, 3%, 5%, all w/w) as a substitute for flour. In this study, as guava leaf powder concentration rose, there was a decrease in the water content level. In addition, color, spread factor, hardness and sensory evaluation of the cookies were examined. The results showed that with an increase in guava leaf powder concentration, the L value decreased significantly, while the values for a and b of cookies increased when more guava leaf power was added to cookies. The spread factor of cookies decreased, but the hardness of cookies increased significantly, as guava leaf powder concentration increased. Cookies containing 0% and 3% of guava leaf powder showed a similar sensory evaluation score in terms of color, taste and flavor of the cookies. In the case of texture and overall consumer acceptability, cookies with 3% of guava leaf powder showed the highest score.