• Journal of Applied Biological Chemistry
• /
• 제51권1호
• /
• pp.28-35
• /
• 2008

The physico-chemical properties of kapok fibers were altered via the combination processes of chlorite-periodate oxidation, in order to assess their efficacy as a heavy metal adsorbent. The chemically-oxidized kapok fibers were found to harbor a certain amount of polysaccharides, together with lowered lignin content. This alteration in lignin characteristics was clearly confirmed via FTIR and NBO yield. Moreover, chemically oxidized kapok fibers retained their hollow tube shape, although some changes were noted. The chemically oxidized kapok fibers evidenced elevated ability to adsorb heavy metal ions with the best fit for the Langmuir adsorption isotherm model. Three cycles of adsorption-desorption were conducted with in-between regeneration steps. Our experimental results indicated that chemically oxidized kapok fibers possessed excellent adsorption characteristics, and the modified kapok fibers could be completely regenerated with almost equimolar diluted sodium hydroxide. Pb, Cu, Cd and Zn ions evidenced adsorption rates of 93.55%, 91.83%, 89.75%, and 92.85% on the chemically oxidized kapok fibers. The regeneration efficiency showed 73.58% of Pb, 71.55% of Cu, 66.87% of Cd, and 75.00% of Zn for 3rd cycle with 0.0125N NaOH.

• Composites Research
• /
• 제14권6호
• /
• pp.16-23
• /
• 2001

인발 와인딩에 의한 섬유강화 복합재료 중공 봉의 기계적 거동해석을 수행하였다. 이 목적의 수행을 위해 새롭게 제작된 와인더를 전통적 인발 시스템에 부탁하여 시편을 제작하였다. 또한 인발-와인딩된 시편을 제작할 수 있는 새로운 공법을 개발하였다. 이 연구를 위해 유한요소 해석 프로그램 POSTII를 확장 개발하였다. 비선형유한요소 수식화에는 2차 피올라-키르히호프 응력 텐서와 그린 변형률 텐서에 기초한 업데이트된 라그란지언 표현법이 사용되었다. 복합재료 중공봉의 유한요소 모델링을 위해 8절점 응축쉘요소를 사용하였다. 파손평가를 위해 모든 유한요소의 각 단층에서의 평균응력을 최대음력 판정법에 대입하였다. 수치해석 예로서 불포화 섬유강화 복합재료 중공 봉의 기계적 거동을 초기 하중상태에서 최종 붕괴가지 조사하였다. 파손에 따른 강성저하와 응력제하를 고려한 유한요소해석 결과는 극만 하중과 파손 및 변형에서 실험치와 잘 일치하였다.

• 제어로봇시스템학회:학술대회논문집
• /
• 제어로봇시스템학회 2004년도 ICCAS
• /
• pp.165-170
• /
• 2004

The purpose of this work was to assess and quantify the beneficial effects of long-term gas exchange, at varying frequencies, for the development of a vibrating intravascular lung assistance device (VIVLAD), for patients suffering from acute respiratory distress syndrome (ARDS). The experimental design and procedure have been applied to the construction of a new device for assessing the effectiveness of membrane vibrations. An analytical solution has been developed for the hydrodynamics of flow through a bundle of sinusoidally vibrated hollow fibers, with the intention of gaining insight into how wall vibrations might enhance the performance of the VIVLAD. As a result, the maximum oxygen transfer rate was reached at the maximum amplitude and through the transfer of vibrations to the hollow fiber membranes. The device was excited by a frequency band of 7Hz at various water flow rates, as this frequency was the 2nd mode resonance frequency of the flexible beam. 675 hollow fiber membranes were also bundled, within the blood flow, into the device.

• Membrane and Water Treatment
• /
• 제7권5호
• /
• pp.463-476
• /
• 2016

In this study, application of polypropylene hollow fiber membrane contactors for $CO_2$ removal from water in liquid-liquid extraction (LLE) mode was simulated. For this purpose, a steady state 2D mathematical model was developed. In this model axial and radial diffusion was considered to $CO_2$ permeation through the hollow fibers. $CO_2$ laden water is fed at a constant flow rate into the lumen side, permeated through the pores of membrane and at the end of this process, $CO_2$ solution in the lumen side was extracted by means of aqueous diethanolamine (DEA) and chemical reaction. The simulation results were validated with the experimental data and it was found a good agreement between them, which confirmed the reliability of the proposed model. Both simulation and experimental results confirmed the reduction in the percentage of $CO_2$ removal by increment of feed flow rate.

• 한국소음진동공학회논문집
• /
• 제22권7호
• /
• pp.626-633
• /
• 2012

In this paper, sound pressure sensitivity of the fiber optic acoustic sensor according to sensor direction and mandrel material were investigated experimentally. Three different directions were selected as stand, lay, and hole. Hollow cylinder type mandrel dimension is 30 mm in outer diameter, 45 mm in length, and 2 mm in thickness, and about 50 m optical fibers were wounded on the surface of the mandrel. Non-directional sound speaker was used as a sound source. Sagnac interferometer and single mode fiber, a laser with 1,550 nm in wavelength, $2{\times}2$ coupler were used. Based on the experimental results, lay direction's sensitivity is the highest in the frequency range of 2 kHz~4 kHz. 'PTFE+carbon' material is more sensitive than PTFE in the frequency range of 5 kHz~20 kHz. Sound pressure detection sensitivity depends on the mandrel direction and material under certain frequency.

• 멤브레인
• /
• 제17권4호
• /
• pp.381-386
• /
• 2007

니켈입자와 고분자를 함유한 니켈슬러리를 상전환법을 이용하여 중공사 형태로 성형한 후, 소결법을 이용하여 $1,150^{\circ}C$ 환원조건에서 소결하여 금속 필터를 제조하였고 니켈 입자를 표면에 함침한 후, $800^{\circ}C$ 환원조건에서 소결하여 금속 정밀여과막을 제조하였다. 소결조건에 따른 금속 중공사 필터와 정밀여과막의 기공크기, 강도를 살펴보았다. 금속 중공사 정밀여과막은 산, 염기 및 염소에 대한 저항성이 뛰어났으며 역세척에 의한 투수량 회복률이 우수하였다.

• 한국세라믹학회지
• /
• 제48권3호
• /
• pp.228-235
• /
• 2011

Sintering behavior and lightweight characteristics of porcelain by addition of FAHM (Fly-Ash Hollow Microsphere) were evaluated. Green body of Backja composition (general porcelain) in which FAHM was added(15 and 20 wt%) was made by slip casting method. The green body was sintered at 1270 and $1290^{\circ}C$ and maintained for 1h. The bulk density and linear shrinkage of the sintered body with FAHM (20 wt%) decreased. As the contents of FAHM. increased, mullite and cristobalite phases increased. In the microstructure, FAHM shells remained after sintering, and the generation of mullite fibers around FAHM shells also were confirmed. the weight of porcelain with of 20% FAHM decreased by 40% and residual FAHM shells promoted the mullite of generation in the matrix.

• 한국정밀공학회:학술대회논문집
• /
• 한국정밀공학회 2003년도 춘계학술대회 논문집
• /
• pp.1332-1335
• /
• 2003

This paper presents the enhancement of oxygen transfer efficiency using the vibrating intravascular lung assist device (VIVLAD) in in-vitro experiments for patients having chronic respiratory problems. The test section was a cylinder duct with the inner diameter of 30 mm. The flow rate was controlled by the pump and monitored by a built-in flow meter. The vibration apparatus was composed of a piezo-vibrator, a function generator. and a power amplifier. The direction of vibration was radial to the fluid flow. Gas flow rates of up to 6 l/min through the 120-cm-Jong hollow fibers have been achieved by exciting a piezo-vibrator. The output of PVDF sensor were investigated by various frequencies in VIVLAD. The experimental results showed that VIVLAD would be enhance oxygen transfer efficiency.

• Korean Chemical Engineering Research
• /
• 제48권5호
• /
• pp.660-667
• /
• 2010

본 연구에서는 고분자 막을 이용하여 6대 온실가스 중 가장 높은 지구온난화지수를 갖는 육불화황(sulfur hexafluoride, $SF_6$)의 회수에 관한 연구를 실시하였다. 막 소재로 이미드 계열의 Matrimid 5218 소재를 건/습식 상전이 법을 이용하여 중공사 형태로 제조하고, 표면 실리콘 코팅 후 모듈을 제조하였다. 제조된 중공사 막은 전자주사현미경 관찰을 통하여 외부 표면에 치밀한 선택층과 망상구조의 하부로 이루어진 비대칭 구조를 확인하였다. 막의 기체투과 특성 확인을 위하여 온도와 압력 변화에 따른 $N_2$, $SF_6$ 단일 기체투과를 실시하였으며, 운전 조건에 따라서 0.78~1.36 GPU의 $N_2$ 투과도와 2.44-5.08의 $N_2/SF_6$ 선택도를 나타냈었다. 제조된 모듈의 혼합기체 분리거동 관찰을 위하여 10 vol.% $SF_6$ 농도를 갖는 $N_2/SF_6$ 혼합기체를 이용하여 온도, 압력, retentate 유량을 달리하여 실시하였으며, 실험을 통하여 압력과 온도 증가 및 retentate 유량 감소에 따라서 회수된 가스 중에 $SF_6$의 농도는 증가되어 최고 37.5 vol.%를 나타낸 반면 회수율은 감소되는 경향을 나타내었으며, 동일한 온도와 압력에서 retentate 유량 증가에 따라서 $SF_6$ 농도는 감소되는 반면 회수율이 증가하여 최고 89%의 회수율을 나타내었다.

• 동력기계공학회지
• /
• 제19권3호
• /
• pp.5-10
• /
• 2015

Femtosecond laser machining has been applied for creating a sensor function in silica glass optical fibers. Femtosecond laser pulses make it possible to fabricate micro structures in processed regions of a very thin glass fiber line because femtosecond laser pulses can extremely minimize thermal effects. With the laser machining to optical fiber using a single shot of 210-fs laser at a wavelength of 800 nm, it was observed that a processed region surrounded a thin layer which seemed to be a hollow cavity monitored by scanning electron microscopy (SEM). This study aims at a theoretical investigation for the processed region by using a numerical analysis in order to embed sensing function to optical fibers. Numerical methods based finite element method (FEM) has been used for an optical waveguide modeling. This report suggests two types modeling and describes a comparative study on optical losses obtained by the experiment and the numerical analysis.