• Proceedings of the Korea Institute of Fire Science and Engineering Conference
• /
• 2011.11a
• /
• pp.506-509
• /
• 2011

압축공기 포는 공기포혼합기를 사용하여 약제와 물 그리고 압축공기를 혼합하여 방출하는 방식으로, 물의 확보가 곤란한 장소라도 소화 효율을 높이는 시스템으로서 주목되고 있으며, 현재 해외 선진국에서는 이미 개발되어 상용화 되어있다. 본 연구에서는 국제적 기준에 따른 압축공기포소화설비의 성능평가시험을 위해 미국, 캐나다 등에서 채택한 UL-162 시험방법을 적용하여 시험을 수행하였으며, 그 결과 기존의 포소화시스템과 압축공기포소화시스템의 성능비교시험을 통해 압축공기포가 기존의 포소화방식 보다 소화성능이 우수한 것으로 나타났다.

• Resources Recycling
• /
• v.9 no.6
• /
• pp.36-44
• /
• 2000

Fly ash was composed of the unburned carbon and mineral particles. The former was able to attach on the bubbles, while the latter was not. Therefore, it was possible to separate the unburned carbon and the mineral from fly ash using the froth flotation process. This study was carried out to evaluate the separation efficiency as a function of the ny ash particle properties in the column flotation. Separation efficiency was analyzed for various size fraction of -38 fm,38~125 fm and 1125 W, and for various fly ash samples containing 7, 11, and 20 wt% unburned carbon. For the size fractions of -38 fm containing 7 wt% unburned carbon, separation efficiency was 86ft, whereas separation efficiency was found to be 74% for the size fraction of +125$\mu\textrm{m}$ containing 20 wt% unburned carbon. The results indicated that separation efficiency increased with the decrease in the particle size and the unburned carbon content of the fly ash.

• Proceedings of the Korean Geotechical Society Conference
• /
• 2010.09a
• /
• pp.708-711
• /
• 2010

본 연구에서는 경량혼합토 배합설계변수인 원료토의 중량, 함수비 및 기포재와 첨가할 물의 양, 그리고 강도를 발현하기 위하여 필요한 고화재로서 시멘트첨가량에 대한 최적의 배합설계에 대한 분석을 하였다. 분석을 위해 폐타이어가루와 왕겨를 각각 혼합한 경량혼합토의 압축강도를 비교 분석하였다. 왕겨혼합토는 함유량 3%에서 최대강도가 발현되는 반면 폐타이어혼합토의 경우 함유량 6%에서 최대강도를 보여주었다. 현장에서 설계기준을 만족하기 위한 시멘트비와 폐성분을 적절히 혼합하면 합리적이고 경제적인 배합비를 산출할 수 있다.

• Journal of Power System Engineering
• /
• v.16 no.3
• /
• pp.37-43
• /
• 2012

감온액정을 추적입자로 사용한 PIV(Particle Image Velocimetry)법이 온도장을 정량적으로 가시화하기 위하여 사용되었다. 이 방법은 전체 유동장과 온도장을 동시에 계측할 수 있는 방법이지만, 온도장의 온도는 온도에 따라 변화되는 액정의 색을 정량적 온도 값으로 변환시켜야한다. 따라서 본 연구에서는 감온액정에 의한 온도장의 광학적 정보를 정량적 온도로 변환시키는 신경회로망 보정기법을 개발하여 그 타당성을 검토한 후, 수직온도구배를 가진 액체의 기포에 의한 대류유동에 적용하여 기포에 의한 온도혼합과정을 정량적으로 가시화하고자 한다.

• The KSFM Journal of Fluid Machinery
• /
• v.12 no.6
• /
• pp.47-53
• /
• 2009

Ozone is a strong oxidant and a powerful disinfectant. In general, it has been used in drinking water treatment during last 100years. Ozone dissolution features are defined by the two categories of ozone contactors, bubble-diffuser and sidestream ozone contactor. Currently, sidestream-injection systems are gaining in popularity but operating cost might be slightly higher. Sidestream ozone system dissolve ozone into a sidestream flow via an injection setup or in the main process flow stream in some sidestream arrangements. The sidestream flow is subsequently mixed with the main process flow stream, which is directed to a reation tank or pipeline for oxidation and disinfection reactions. The purpose of this study is to suggest optimal operating pressure, to figure out the static-mixer effect and to understand the microbubble characteristics of ozone to improve dissolution efficiency.

• Clean Technology
• /
• v.27 no.1
• /
• pp.39-46
• /
• 2021

A road structure washing vehicle equipped with a 4 HP, 80 LPM ultrafine bubble generator was used to clean a tunnel wall and the surface of the surrounding structure, consisting of concrete and tiles, in a heavy traffic area around an apartment complex in the city. Ultrafine bubbles were generated by supplying air at 2 to 3 LPM and using a specially designed nozzle, whereas fine bubbles made by an impeller in a gas-liquid mixing self-priming pump were produced with an average diameter of 165.4 nm and 6.81 × 107 particles mL-1. Using a high pressure washer gun that can perform high-pressure cleaning at 150 bar and 30 LPM, ultrafine bubbles were used to wash dust adsorbed on the surface of the road structures. The experimental analysis was divided into before and after washing. The samples were analyzed by applying ISO 8502-3 to measure surface contamination of dust adsorbed on the surface. Using the transparent tape attached to the surface, the removal rate was calculated by measuring the weight of the dust, and the number of particles was calculated using the gravimetric method and the software, ImageJ. The results of the experiment showed that the number of dust particles adsorbed on the tile wall surface before and after washing were 3,063 ± 218 particles mL-1 and 20 ± 5 particles mL-1, respectively, with weights of 580 ± 82 mg and 13 ± 4 mg. Particles on the surface of the concrete structure before and after washing were 8,105 ± 1,738 particles mL-1 and 39 ± 6 particles mL-1, respectively, with weights of 1,448 ± 190 mg and 118 ± 32 mg.

• The Journal of the Acoustical Society of Korea
• /
• v.42 no.4
• /
• pp.313-319
• /
• 2023

In this paper, a time series machine learning model, Long Short Term Memory (LSTM), is applied into the bubble flow noise data and the underwater projectile launch noise data to predict missing values of time-series underwater noise data. The former is mixed with bubble noise, flow noise, and fluid-induced interaction noise measured in a pipe and can be classified into three types. The latter is the noise generated when an underwater projectile is ejected from a launch tube and has a characteristic of instantaenous noise. For such types of noise, a data-driven model can be more useful than an analytical model. We constructed an LSTM model with given data and evaluated the model's performance based on the number of hidden units, the number of input sequences, and the decimation factor of signal. It is shown that the optimal LSTM model works well for new data of the same type.

• Korean Journal of Organic Agriculture
• /
• v.20 no.4
• /
• pp.703-713
• /
• 2012

Three types of aeration system were installed in experimental liquid fertilization tanks to investigate the change of characteristics of pig slurry used as a raw material for making livestock liquid fertilizer. The aeration systems of the reaction tanks were composed of three major part: the air suppling part (blower), the air pipe part, and the air diffuser part. In the first tank (reactor A), the air was supplied from the bottom of the reaction tank through air pipe system connecting air diffuser with commercial ordinary blower. In the second tank (reactor B), the air diffuser was located 10cm above the bottom of the reactor. In the third tank (reactor C), the pure air was supplied with circulating pjg slurry. The oxygen content of pure air was about 90%. The pure air was mixed with pig slurry by mechanically in the air suppling part (blower) and the air pipe part. The agitation effect was highest in the reactor C than other reactors. The contents of SS, COD, T-N and T-P of each samples collected at middle part of all reactors were 8,500, 4,188, 694 and 422mg/L; 9,000, 4,247, 813 and 356mg/L; 8,667, 6,910, 973 and 269mg/L, respectively.

• Korean Journal of Microbiology
• /
• v.37 no.2
• /
• pp.130-136
• /
• 2001

The killing effects of two types(one-phase reactor and two-phase reactor) of UV-TiO$_2$photocatalytic system on the microorganisms have been studied. The UV-lamp which emits maximum 39 watts at 254 nm was prepared in these system. Three types of $TiO_2$ coating method were adopted. One type is thin film coated form on the quartz tube in the reactor and another one is surface rough coated form on the glass bead. The other one is $TiO_2$-mixed alginate bead form. UV irradiation was carried out for 1 min. In case of one phase reactor, the bactericidal efficiencies of E. coli by $TiO_2$-coated quartz tube and $TiO_2$-coated glass bead were 63.2% and 89.9%, respectively. In the air-bubbling system, the bactericidal efficiency was 95%, however, the efficiency decreased to 90.6% in the non-bubbling system. In the $TiO_2$-mixed alginate bead system, bactericidal efficiency was 86%. When $H_2O$$_2$ was treated (10, 15, 20, and 25 mg/ι) to the $TiO_2$-coated glass bead reactor, bactericidal efficiency significantly increased according to the concentration of $H_2$$O_2$. Two phase reactor showed more elevated efficiency. E. coli was more sensitive to the reaction than S. cerevisiae.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.18 no.2
• /
• pp.226-234
• /
• 2017

The physical properties of lightweight foamed concrete mixed with EPS waste and flame resistant EPS waste were investigated. For this purpose, the main variables considered were a cement content of 300 and $400kgf/m^3$ and an EPS replacement ratio of 0, 10, 20, 30, and 40% by the volume ratio of the foam. The water-cement ratio and the dilution concentration were fixed to 0.5 and 10% respectively. The test results showed that the apparent density meets degrees 0.5 and 0.6 of KS F4039, and they showed little difference between the two mixes of Type A and Type B, regardless of the unit cement content. The bending strength obtained through the compressive strength also met the degree of KS F 4039. The thermal conductivity was 1~3% higher for the mixes of EPS than the case of flame resistant EPS, but both mixes met the 0.4 degree of KS F4039. The absorption ratio showed the values above 20% with a 1~3% difference for the two mixes, which mean further studies will be needed to reduce the absorption ratio.