• Title/Summary/Keyword: Void Removal

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Effect of Nano-Bubble on Removal of Complex Heavy Metals (나노버블이 복합중금속(구리/납) 오염물 제거에 미치는 영향 분석)

  • Lee, Yang-Gyu;Han, Jung-Geun;Choi, Ju-Hyun;Kim, Dong-Chan;You, Seung-Kyong;Hong, Kikwon
    • Journal of the Korean Geosynthetics Society
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    • v.14 no.4
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    • pp.139-146
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    • 2015
  • This paper describes a effect of nano-bubble on removal of complex heavy metals, in order to remove pollutants of soil with copper (Cu) and lead (Pb) based on column test. It was conducted column test considering inflow and fine soil contents condition, and then it was analyzed removal effect of nano-bubble on Cu and Cu/Pb. The test result showed that the removal effect of the nano-bubble was higher than that of distilled water regardless of fine soil contents in case of Cu pollutant, and the removal effect of nano-bubble on heavy metals was found to have a significant impact on Pb than Cu in case of Cu/Pb pollutants. It was also analyzed that engineering properties (like a flow path and permeability) of soil due to void ratio has influenced a significant impact the pollutants removal of nano-bubble. The test results determined that nano-bubble can be applied as a flushing agent for priority target pollutant in complex heavy metals.

A Study on the BOD Removal Characteristics of Aerobic Submerged Biofilter (Media를 충전(充塡)한 간접폭기식(間接曝氣式) 침지여상(浸漬濾床)에 의한 BOD제거 특성에 관한 연구)

  • Yang, Sang Hyun;Kwon, Young Ho
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.14 no.3
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    • pp.669-678
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    • 1994
  • The BOD removal characteristics of submerged biofilters filled with three kinds of filter media respectively were experimentally examined with constant temperature, pH value and variable BOD loading and recirculation ratio. Obtained results are as follows; 1. The BOD removal ratio decreases with the increasing $BOD_5$ volumetric loading rate, and the loading rate for the BOD removal over 90% is lower thean $1.6kg{\cdot}BOD_5/m^3{\cdot}d$ for the plastic media of Netring and cubic wire meshes. This is a much large value than $0.3{\sim}0.8kg{\cdot}BOD_5/m^3{\cdot}d$ for conventional activated sludge process. The required submerged biofilter volume is found to be much samller than that of conventional activated sludge process. 2. The decreasing order of BOD removal is Netring (random plastic media), cubic wire meshes (plastic module), and then gravel (stone media). This is mainly due to the media characteristics such as void ratio, specific surface area and media shapes. 3. The $BOD_5$ removal rate increases with the recircuration ration, but the rate of increases becomes samaller as the recirculation ratio increases over 20. When $BOD_5$ loading is $1.8kg{\cdot}BOD_5/m^3{\cdot}d$, the required recirculation rationto obtain 90% $BOD_5$ removal is about 20 for Netring and it was about 30 for cubic wire meshes. 4. Reynold's Number increases with recirculation ratio, and the Reynold's Numbers corresponding to the recircuration ratio of 10~50 are less than 52, showing laminar up flows in the filter. The settled and effluent sludges increase with increase of Reynol's Number, and there are the definite Reynold's Numbers at which the settling sludge concentrations become nearly constant respectively in each filters. 5. In this submerged biofilter system, small volume of sludge hopper can be substituted for a separated settling tank.

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Performance Study on Pilot-scale Constructed Wetlands in order to Restore Contaminated Stream (오염하천의 정화를 위한 파일럿 규모의 인공습지 적용)

  • Kim, Seung-Jun;Choi, Yong-Su;Bae, Woo-keun
    • Journal of Korean Society on Water Environment
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    • v.22 no.3
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    • pp.546-556
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    • 2006
  • The purpose of this study is to improve the polluted stream water quality by pilot-scale five different constructed wetlands (CWs). Cell 1 to 3 are newly designed 2SFCW (Surface-subsurface flow CW) with 1 to 3 flow shifters (FS) in the middle of the wetland system. Cell 4 and 5 are control CW (CCW), but Cell 5 is the same type as Cell 3. The FS, which converts the route of surface and subsurface flow between two wetlands connected in series, was able to enhance the treatability of TN via nitrification and denitrification and of SS due to filtration and sedimentation. The void fraction and dispersion number of Cell 1, 2 and 3 obtained from the RTD analysis were found to be 0.73 and 0.17, respectively. COD and TP removal efficiencies of Cell 1 to 3 were similar to that of Cell 4 and 5. SS removal efficiencies of Cell 1 to 3 and 5 with FS were 5-10% higher than that of Cell 4 without FS. TN removal efficiencies of Cell 1 to 3 were 3-14% higher than that of Cell 4 and 5. The average $R^2$ values of COD, SS, TN and TP obtained from nonlinear regression analysis were similar to the results of other researchers.

Trenchless Repairing-Reinforcing Process of Underground Pipes with Advanced Composite Materials (신소재 복합재료를 이용한 비굴착 지하매설관 보수-보강공법)

  • 진우석;권재욱;이대길;유애권
    • Proceedings of the Korean Society For Composite Materials Conference
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    • 2001.10a
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    • pp.43-48
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    • 2001
  • To overcome the disadvantages of conventional excavation technology, various trenchless (or excavation free, or no-dig) repair-reinforcement technologies have been developed and tried. But trenchless technologies so fat developed have some brawbacks such as high cost and inconvenience of operation. In this study, a repairing-reinforcing process for underground pipes with glass fiber fabric polymer composites using VARTM(Vacuum Assisted Resin Transfer Molding) has been developed. The developed process requires shorter operation time and lower cost with smaller and simpler operating equipments than those of the conventional trenchless technologies. For the reliable operation of the developed method, a simple method to apply pressure and vacuum to the reinforcement was devised and flexible mold technology was tried. Also, resin filling and cure status during RTM process were monitored with a commercial dielectrometry cure monitoring system, LACOMCURE. From the investigation, it has been found that the developed repairing-reinforcing technology with appropriate process variables and on-line cure monitoring has many advantages over conventional methods.

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A Case of Calvarial Hemangioma in Cranioplasty Site

  • Kang, Dong-Wan;Choi, Chang-Hwa
    • Journal of Korean Neurosurgical Society
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    • v.46 no.5
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    • pp.484-487
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    • 2009
  • It is not uncommon for hemangiomas to occur in the calvarium, accounting for about 10% of the benign skull tumors. A 46-year-old man was presented with a palpable scalp mass on the left parietal region. Past medical history indicated that he had undergone cranioplasty 25 years prior due to a depressed skull fracture suffered from a traffic accident. Magnetic resonance imaging revealed mixed signal intensity mass on T1 -and T2- weighted images pushing a linear signal void lesion outward in the left parietal region. After total surgical removal along with cranioplasty, he was discharged without neurological deficits. Histological examination of the surgical specimen revealed a cavernous hemangioma. A skull hemangioma occurring at the site of a cranioplasty has not yet been reported. Therefore, authors report this case in combination with a pertinent literature review.

Tensile and High Cycle Fatigue Properties of Ion-nitrided and Nitro-carburized SCr430B Steels (이온질화 및 질탄화 처리된 SCr430B 박판강의 인장 및 피로특성)

  • Park, S.H.;Lee, C.S.
    • Transactions of Materials Processing
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    • v.21 no.6
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    • pp.354-359
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    • 2012
  • Effects of a nitriding treatment on the tensile and high cycle fatigue properties were investigated by conducting ion-nitriding and gas nitro-caburizing treatments on the spheroidized SCr430B medium-carbon steel and performing tensile and tension-tension high cycle fatigue tests. The nitrided samples showed much lower strength and ductility compared to those in the initial as-spheroidized state and premature fracture occurred at the hardened layers. The micro-voids in the compound layer caused fatigue crack initiation. Thus, the removal of the compound layer with micro-voids remarkably improved the fatigue resistance to even beyond that of the as-spheroidized sample.

Analysis of Partial Discharge in High Voltage Motor Model Coils (고압전동기 모델 코일의 부분방전 분석)

  • Kim, Hee-Dong;Kong, Tae-Sik
    • Proceedings of the KIEE Conference
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    • 2005.07c
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    • pp.2091-2093
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    • 2005
  • Five model coils of 6.6kV motor were manufactured with several defects. These stator coils have artificial defects such as void of groundwall insulation, removal of semi-conductive coating and damage of strand insulation. Epoxy-mica coupler(80 pF) was connected to five model coil terminals, respectively The voltage applied to the coils was 3.81kV, 4.76kV, 6.0kV and 6.6kV. Partial discharge(PD) tests performed in the laboratory and shield room. Digital PD detector (PDD) and turbine generator analyzer(TGA) were used to measure PD activity. TGA summarizes each plot with two quantities such as the normalized quantity number(NQN) and the peak PD magnitude(Qm). The PD levels in pC were measured with PDD. PD patterns of model coils were indicated the internal and slot discharges. PD patterns coincide with both PDD and TGA.

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Milling of NiCo Composite Silicide Interconnects using a FIB (FIB를 이용한 니켈코발트 복합실리사이드 미세 배선의 밀링 가공)

  • Song, Oh-Sung;Yoon, Ki-Jeong
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.9 no.3
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    • pp.615-620
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    • 2008
  • We fabriacted thermal evaporated $10nm-Ni_{1-x}Co_x$(x=0.2, 0.6, and 0.7) films on 70 nm-thick polysilicon substrate with $0.5{\mu}m$ line width. NiCo composite silicide layers were formed by rapid thermal annealing (RTA) at the temperatures of $700^{\circ}C$ and $1000^{\circ}C$. Then, we checked the microstructure evaluation of silicide patterns. A FIB (focused ion beam) was used to micro-mill the interconnect patterns with low energy condition (30kV-10pA-2 sec). We investigated the possibility of selective removal of silicide layers. It was possible to remove low resistance silicide layer selectively with the given FIB condition for our proposed NiCo composite silicides. However, the silicides formed from $Ni_{40}Co_{60}$ and $Ni_{30}Co_{70}$ composition showed void defects in interconnect patterns. Those void defects hinder the selective milling for the NiCo composite silicides.

Development of Flexure Applied Bond head for Die to Wafer Hybrid Bonding (Die to Wafer Hybrid Bonding을 위한 Flexure 적용 Bond head 개발)

  • Jang, Woo Je;Jeong, Yong Jin;Lee, Hakjun
    • Journal of the Semiconductor & Display Technology
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    • v.20 no.4
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    • pp.171-176
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    • 2021
  • Die-to-wafer (D2W) hybrid bonding in the multilayer semiconductor manufacturing process is one of wafer direct bonding, and various studies are being conducted around the world. A noteworthy point in the current die-to-wafer process is that a lot of voids occur on the bonding surface of the die during bonding. In this study, as a suggested method for removing voids generated during the D2W hybrid bonding process, a flexible mechanism for implementing convex for die bonding to be applied to the bond head is proposed. In addition, modeling of flexible mechanisms, analysis/design/control/evaluation of static/dynamics properties are performed. The proposed system was controlled by capacitive sensor (lion precision, CPL 290), piezo actuator (P-888,91), and dSpace. This flexure mechanism implemented a working range of 200 ㎛, resolution(3σ) of 7.276nm, Inposition(3σ) of 3.503nm, settling time(2%) of 500.133ms by applying a reverse bridge type mechanism and leaf spring guide, and at the same time realized a maximum step difference of 6 ㎛ between die edge and center. The results of this study are applied to the D2W hybrid bonding process and are expected to bring about an effect of increasing semiconductor yield through void removal. In addition, it is expected that it can be utilized as a system that meets the convex variable amount required for each device by adjusting the elongation amount of the piezo actuator coupled to the flexible mechanism in a precise unit.

Influence Analysis on the Number of Ruptured SG u-tubes During mSGTR in CANDU-6 Plants (중수로 증기발생기 다중 전열관 파단사고시 파단 전열관 수에 대한 영향 분석)

  • Seon Oh Yu;Kyung Won Lee
    • Transactions of the Korean Society of Pressure Vessels and Piping
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    • v.18 no.2
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    • pp.37-42
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    • 2022
  • An influence analysis on multiple steam generator tube rupture (mSGTR) followed by an unmitigated station blackout is performed to compare the plant responses according to the number of ruptured u-tubes under the assumption of a total of 10 ruptured u-tubes. In all calculation cases, the transient behaviour of major thermal-hydraulic parameters, such as the discharge flow rate through the ruptured u-tubes, reactor header pressure, and void fraction in the fuel channels is found to be overall similar to that of the base case having a single SG with 10 u-tubes ruptured. Additionally, as the conditions of low-flow coolant with high void fraction in the broken loop continued, causing the degradation of decay heat removal, the peak cladding temperature (PCT) would be expected to exceed the limit criteria for ensuring nuclear fuel integrity. However, despite the same total number of ruptured u-tubes, because of the different connection configuration between the SG and pressurizer, a difference is foud in time between the pressurizer low-level signal and reactor header low-pressure signal, affecting the time to trip the reactor and to reach the PCT limit. The present study is expected to provide the technical basis for the accident management strategy for mSGTR transient conditions of CANDU-6 plants.