• Journal of Korean Society of Water and Wastewater
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• v.23 no.4
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• pp.439-446
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• 2009

This study was performed to evaluate SND(simultaneous nitrification and denitrification)efficiency, nitrogen removal efficiency and filtration function of non-woven fabric by using submerging MBR packed with granular sulfur covered with non-woven fabric filter. Synthetic wastewater was used as influent wastewater. Concentration of $NH_4{^+}-N$ in influent was maintained about 40 mg/L and the experiment was performed in four phases according to the flow rate. Nitrogen loading rate divided four phases ranging from $0.04 kg\;NH_4{^+}-N/m^3-day$ to $0.16 kg\;NH_4{^+}-N/m^3-day$. As a result, the maximum $NH_4{^+}-N$ removal rate was accomplished at $0.142 kg\;NH_4{^+}-N/m^3-day$ in nitrogen loading of $0.147 kg\;NH_4{^+}-N/m^3-day$. Nitrification efficiency was higher than 95% in all phases. $NO_3{^-}-N$ loading rate was adjusted ranging from $0.22 kg\;NO_3{^-}-N/m^3-day$ to $0.89 kg\;NO_3{^-}-N/m^3-day$. The maximum $NO_3{^-}-N$ removal rate was accomplished up to $0.71 kg\;NO_3{^-}-N/m^3-day$ in $NO_3{^-}-N$ loading of $0.89 kg\;NO_3{^-}-N/m^3-day$. The maximum $NO_3{^-}-N$ removal efficiency was 95% in $NO_3{^-}-N$ loading of $0.22 kg\;NO_3{^-}-N/m^3-day$. T-N removal rate was 90% and concentration of T-N in effluent was 3.7 mg/L in T-N loading rate of $0.039 kg\;NO_3{^-}-N/m^3-day$. In this study, TMP in reactor with and without non-woven fabric filter were observed to define fouling of hollow-fiber membrane module. Reaching time to standard washing pressure(22 cm Hg) of two reactors were 29 days with non-woven fabric But the reactor without non-woven fabric reached standard washing pressure only after 4 days. Accordingly, non-woven fabric was demonstrated the superiority as a filtration ability. With high nitrogen removal rate and decreasing of fouling of membrane, MBR packed with granular sulfur covered with non-woven fabric filter submerging in activated sludge aeration tank can be used as an advanced treatment process.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.02a
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• pp.361-361
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• 2013

비냉각 적외선 검출소자는 빛이 전혀 없는 환경에서도 사물을 감지하는 열상장비의 핵심소자이다. 마이크로볼로미터 적외선 검출기는 상온에서 동작하며, 온도안정화를 위해 TEC를 장착하여 진공패키지로 조립된다. 패키지는 진공을 유지할 수 있도록 일반적으로 메탈로 제작되며, 단가 감소 및 생산성 증대를 위해 wafer level packaging 방법을 이용한다. 마이크로볼로미터의 특성은 패키지의 진공 변화에 매우 민감하다. 센서의 감도를 증가시키기 위해서는 진공환경을 유지해야 한다. 볼로미터 소자의 특성은 상압에서 열전도는 기판과 멤브레인 사이의 에어갭을 통해 열손실을 야기하므로 센서의 반응도가 현저히 줄어든다. 에어갭이 1 um 정도 되더라도 그 사이에 존재하는 열전도가 가능하므로 진공을 유지하여 열고립 상태를 증대시킬 수 있다. 이에 본 연구에서는 소자의 동작시 압력, 즉 진공도가 볼로미터 소자의 반응도 특성에 미치는 영향을 조사하였다. 마이크로볼로미터 소자는 $2{\times}8$ 어레이 형태로 제작하였으며, metal pad를 각 단위셀에 배치하였으며, 공통전극으로 한 개의 metal pad를 넣어 설계하였다. 흡수체로써 VOx를 사용하였으며, 열 고립구조를 위해 2.5 um 공명 흡수층의 floating 구조로 멤브레인을 형성하였다. 진공패키지는 메탈패키지를 제작하여 볼로미터 칩을 TEC 위에 장착하였으며, 신호의 감지를 위해 가변저항을 매칭시켰다. 반응도는 신호 대 잡음 값을 획득하여 소자에 도달하는 적외선 에너지에 대해 반응하는 값을 계산에 의해 얻어내는 것이다. 픽셀 크기는 $50{\times}50$ um이며, 패키지 조립 공정 후 온도변화에 따른 저항 측정을 통해 TCR 값을 얻었다. 이때 TCR은 약 -2.5%/K으로 나타났다. $2{\times}8$의 4개 단위소자에 대해 측정한 값은 균일하게 TCR 값이 나타났다. 광반응 특성은 볼로미터 단위소자에 대해서 먼저 고진공(5e-6 torr) 하에서 측정하였으며, 반응도는 25,000 V/W의 값을 나타내었고, 탐지도는 약 2e+8 $cmHz_{1/2}$/W로 나타났다. 패키지의 압력 조절을 위해 TMP 및 로터리 펌프를 이용하여 100 torr에서 1e-4 torr의 범위에서 압력조절 밸브를 이용하여 질소가스의 압력으로 진공도를 변화시켰다. 적외선 반응신호는 압력이 증가함에 따라 감소하였으며, 2e-1 torr의 압력에서 신호의 크기가 감소하기 시작하여 5 torr에서 반응도의 1/2 값을 나타냄을 알 수 있었다. 30 torr 이상에서는 신호가 잡음값 과거의 동일하여 신호대 잡음비가 1로 나타남을 알 수 있었다. 또한 진공도 변화에 대해, 흑체온도에 따른 반응도 및 탐지도의 특성을 조사한 결과를 발표한다. 반응도의 증가를 위해 진공도는 진공도는 1e-2 torr 이하의 압력을 유지해야 함을 본 실험을 통해 알 수 있었다.

• KSBB Journal
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• v.16 no.4
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• pp.403-408
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• 2001

Distillation condensate generated from downstream processing of microbial alcohol fermentation imposes a serious burden to biological wastewater treatment or anaerobic digestion due to its high contents of SS (suspended solids) and TN (total nitrogen), A pilot scale microfiltration of the stillage condensate with a stainless steel SCEPTER membrane of 0.1 ${\mu}$m pore size was carried out to remove SS which was mostly composed of microbial cell residue. A stable permeate flux was achieved when the decanter effluent containing 0.7% of SS was filtered under the conditions of X10 VCR (volume concentration ratio), 2.5 bar of TMP (transmembrane pressure), and 60$^{\circ}C$. When stillage condensate with 2.6% SS was treated directly with microfiltration, VCR below X3 was recommended for a long duration of filtration. The permeate and retentate obtained from microfiltration were recycled to make-up medium of fermentation. Adding permeate or retentate up to 30% of fermentation volume showed no distinguished undesirable influence during the course of alcohol fermentation. Although only slight improvements in the final amount of CO$_2$ evolution and alcohol content were observed, fermentation rate increased so that the required time to reach 450 L/ton of CO$_2$ evolution was shortened to 72% of that with normal media.

• Membrane Journal
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• v.15 no.4
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• pp.338-348
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• 2005

The permeate flux decline on microfiltration capillary membrane operation was investigated with inorganic colloidal solutions. The permeate flux of the alumina solution is two times higher in average than that of the bentonite solution. The flux decline with increase in operation time was less in the alumina solution than in the bentonite solution. The rate of initial flux decline until 10 min was higher on the bentonite solution over the alumina solution. The decline in permeate flux was due to both the cake formation and the pore blocking. The latter effect was higher in the operation of the bentonite solution. In comparing the ratio of each fouling component to the total fouling fur the $1.0\;kg_f/cm^2$ TMP condition, complete blocking was $9.35\%$, standard blocking was about $6.82\%$ and cake filtration was $83.83\%$, respectively. With the increase in cross flow velocity, the permeate flux increased by $6.0\%$ for the alumina solution and by 14.0 for the bentonite solution. With the increase in average pore size fromm $0.24\;{\mu}m\;to\;0.34\;{\mu}m$, the permeate flux increases 1.61 times for the alumina solution and 1.76 times far the bentonite solution.

• Clinics in Shoulder and Elbow
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• v.17 no.2
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• pp.64-67
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• 2014

Background: The purpose of this study was to determine whether in patients with rotator cuff tears a correlation exists between molecular changes and clinical parameters such as age, duration of symptom, range of motion, and tear size. Molecular changes of matrix metalloproteinase (MMP) and tissue inhibitor of metalloproteinase (TIMP) were assessed by measuring messenger RNA (mRNA) levels of the two proteins. Methods: The rotator cuff tissue from was obtained from the edge of a torn tendon revealed after debridement by a motorized shaver. Using the sample of rotator cuff tissue, the reverse transcription polymerase chain reaction was performed to quantify MMP-2 and TIMP-2 mRNA expression. To determine whether mRNA levels and the clinical variables, such as age, defect size, range of motion (ROM) of shoulder, and duration of symptoms, show any correlation, Spearman's correlation coefficients were used to test for significant differences. Results: There was an inverse correlation between the mRNA levels of MMP-2 and TIMP-2 from the torn rotator cuff tendons regardless of the clinical variables. However, comparison of mRNA levels versus clinical parameters such as age, defect size, range of motion and duration of symptoms revealed a number of findings. We found a significant correlation between age and mRNA levels of MMP-2 from torn cuffs (r = 0.513, p = 0.021). Further, we found a significant correlation between defect size in the full thickness tears and mRNA levels of MMP-2 (r = 0.454, p = 0.045). Conversely, no significant association between mRNA levels of MMP-2 and ROM or duration of symptom was found. Conclusions: Our results suggest that both MMP-2 and TIMP-2 may be involved in the disease process of rotator cuff tears. Although the level of mRNA expression of MMP-2 and TMP-2 remain constant in torn rotator cuffs irrespective of the clinical variables, their levels may be influenced by age and defect size, which could account to change in tendon degradation and the healing process.

• Membrane Journal
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• v.15 no.1
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• pp.52-61
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• 2005

Permeate flux decline in a microfiltration was analyzed by measuring the permeability of bentonite colloidal solution through polyethylene capillary membranes. The flux decline with time was due to the growth of cake layer on the membrane surface and to the pore blocking by particles. As the time approaches to steady state, the permeate flux is almost controlled by the cake filtration model. Faster flux decline at high trans-membrane pressure was attributed to the formation of denser packed cake layer and pore blocking. The ratio of permeate flux to the initial permeate flux, J/J₁, decreased with increasing the trans-membrane pressure, from 45% for 0.5 kg/sub f//㎠ to 38% for 2.0 kg/sub f//㎠. In comparing the ratio of each fouling component to the total fouling for the 0.5 kg/sub f//㎠ TMP condition, complete blocking was 23.4%, standard blocking was about 14.6% and cake filtration was 62.0%, respectively. Permeate flux through the membrane increases with cross flow velocity, and the effect of the variation of velocity is more significant at 1.0 kg/sub f//㎠ rather than at 2.0 kg/sub f//㎠ of the operation pressure. Permeate flux for the membrane having the average pore diameter of 0.34 ㎛ was higher than that for the membrane of 0.24 ㎛ pore size, with the higher flux with the low concentration of feed. On the operation using the membrane of 0.34 ㎛ pore, the pore blocking in the low concentration of 200 ppm is negligible relative to the pore blocking in the 1000 ppm feed.

• Membrane Journal
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• v.13 no.2
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• pp.65-72
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• 2003

This study was focused on the investigation of filtration characteristics of membrane-coupled fermentor system for dissolved organics recovery from liquid organic sludge. On the filterability of MF over the range of $0.1{\sim}5 {\mu}m,$ the magnitude of total membrane resistance ($R_t$) is ranged as follows in the order; $0.1 {\mu}m>0.2{\mu}m>0.5 >1{\mu}m>2{\mu}m>5{\mu}m$. The cake layer resistance ($R_c$) occupied about 68~88% of total resistance with fermented sludge. Permeation flux decline was mainly attributed to the $R_c$, which was formed by a strong deposition from physico-chemical interactions of solids on membrane surface. Higher suspended solids (SS) concentration of suspension caused lower permeation flux. However, there was not a proportion relation beyond a certain SS concentration. The cross-flow velocity on the membrane surface was faster, which resulted in the higher permeation flux and also more efficient with low trans membrane pressure (TMP) in viewpoint of energy efficiency. The appropriate pH of suspension was over the range of 5.0~6.0 for dissolved organics recovery as well as the permeation flux. It is possible f3r bacteria to be separated perfectly with $0.1{\mu}m\; and \;0.2{\mu}m$ membrane pore size. Based on experimental results, most appropriate membrane pore size for the recovery is believed to around $1{\mu}m$.

• Journal of the Korean Geotechnical Society
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• v.39 no.12
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• pp.93-102
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• 2023

Despite recent modifications to building structural standards emphasizing the seismic stability of building foundations, the current design focus remains solely on vertical support, resulting in insufficient consideration of horizontal loads during earthquakes. In this study, we evaluated the dynamic behavior of inclined tripod micropiles (ITMP), which provide additional seismic resistance against horizontal and vertical loads during earthquakes. A comparison of the dynamic characteristics, such as acceleration, displacement, bending moment, and axial force, of ITMP with a 15° installation angle and normal vertical micropiles with a 0° installation angle was performed using dynamic centrifuge model tests. Results show that under moderate seismic loads, the proposed ITMP exhibited lower acceleration responses than the vertical micropiles. However, when subjected to a long-period strong seismic excitation, such as sine (2 Hz), ITMP showed greater responses than the vertical micropiles in terms of acceleration and settlement. These results indicate that the use of ITMP reduces the amplif ication of short-period (high-f requency) contents compared with the use of vertical micropiles. Therefore, ITMP can be used to enhance seismic performance of structures.

• Annals of Hepato-Biliary-Pancreatic Surgery
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• v.28 no.1
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• pp.59-69
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• 2024

Backgrounds/Aims: Pancreaticoduodenectomy (PD) is the only radical treatment for periampullary malignancies. Superior mesenteric artery (SMA) first approach combined with total meso-pancreas (MP) excision was conducted to improve the oncological results. There has not been any previous research of a technique that combines the SMA first approach and total MP excision with a detailed description of the MP macroscopical shape. Methods: We prospectively assessed 77 patients with periampullary malignancies between October 2020 and March 2022 (18 months). All patients had undergone PD with SMA first approach combined total MP excision. The perioperative indications, clinical data, intra-operative index, R0 resection rate of postoperative pathological specimens (especially mesopancreatic margin), postoperative complications, and follow-up results were evaluated. Results: The median operative time was 289.6 min (178-540 min), the median intraoperative blood loss was 209 mL (30-1,600 mL). Microscopically, there were 19 (24.7%) cases with metastatic MP, and five cases (6.5%) with R1-resection of the MP. The number of lymph nodes (LNs) harvested and metastatic LNs were 27.2 (maximum was 74) and 1.8 (maximum was 16), respectively. Some (46.8%) patients had pancreatic fistula, but mostly in grade A, with 7 patients (9.1%) who required re-operations. Some 18.2% of cases developed postoperative refractory diarrhea. The rate of in-hospital mortality was 1.3%. Conclusions: The PD with SMA first approach combined TMpE for periampullary malignancies was effective in achieving superior oncological statistics (rate of MP R0-resection and number of total resected LNs) with non-inferior short-term outcomes. It is necessary to evaluate survival outcomes with long-term follow-up.

• KSBB Journal
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• v.23 no.3
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• pp.231-238
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• 2008

The second family member of tissue inhibitors of matrix metalloproteinases, TIMP-2, is a 21kDa protein which inhibits matrix metalloproteinases 2 (MMP-2). Expression of mammalian proteins in E. coli often forms inclusion bodies that are made up of mis-folded or insoluble protein aggregates. The requirement for the formation of 6 disulfide bonds in the process of the TIMP-2 folding is likely to be incompatible with the reducing environment of E. coli. However, this incompatibility can be often overcome by introducing a mutagenesis that could lead to enhancement of the protein solubility. In this reason, we have attempted to express the soluble TIMP-2 in E. coli by applying a modified staggered extension process (StEP), one of the in vitro PCR-based recombinant mutagenesis methods, and error-prone PCR. C-terminally located CAT fusion protein with respect to mutated TIMP-2 proteins enables us to differentiate the soluble TIMP-2 from the insoluble in E. coli by virtue of chloramphenicol resistance. According to this scheme, E. coli harboring properly-folded CAT fused to TIMP-2 protein was selected, and some of the resulting colonies exhibited an enhanced, soluble expression of TIMP-2 compared to the wild type, implying (i) the StEP technique is successfully employed to enhance the proper folding thereby increasing the solubility of TIMP-2, and (ii) the CAT dependent screening may be a simple and effective method to differentiate the soluble protein expression in E. coli.