• 한국물환경학회지
• /
• 제18권4호
• /
• pp.379-386
• /
• 2002

In this study, estimation model for iron compound originated from upflow, anaerobic fixed bed reactor, which treats sewage domestic wastewater, was developed. The estimation model was formulated by a mathematical expression which was based on the mass balance. Below the HRT of 60 minute, sulfide concentration combining with iron $FeS_2$ is the highest because the maximum sulfate consumption rate $V_{maxS}$ and half-saturation constant of sulfate $K_{mS}$ exert an important effect on the estimation model as temperature was increased. But increment of $FeS_2$ concentration is weakened above the HRT of 60 minutes and represent the lowest value at the HRT of 108 minutes. It implies that liquid phase distribution ratio of sulfide ${\alpha}r$ becomes lower as temperature was increased. While phosphorus concentration combining with iron $Fe_3(PO_4)_3$ is increased as HRT and temperature are increased, which is affected by phosphorus removal rate constant $k_p$. As the result of estimating the iron concentrations of corrosion by the model, the concentration of iron corrosion is higher than any other at the HRT of 108 minute and $20^{\circ}C$. The predicted values were compared with measured ones at different HRT(13.5, 27, 54, 108 min) and temperature(20, 25, $30^{\circ}C$). The experimental data could be fitted with the simulated curves. Therefore, the mathematical expression could be applicable to design full-scale wastewater treatment plants.

• 상하수도학회지
• /
• 제25권3호
• /
• pp.391-398
• /
• 2011

This study is to develop highly efficient coagulation system(HECS) that runs treatment with a short retention time to cover the overflow in the rain, which coagulation, mixing and settling are contacted in a single reactor and to estimate the applicability. Setting up 100ton/day-size pilot scale plant, the results of continuous operation in case of runoff, maintaining 20 minute-retention time at optimum chemical injection condition(Alum 100mg/L, Polymer 1.0mg/L) shows the highest removal efficiency(Turbidity 93.1%, TCODcr 80.6%, BOD 81.8%, SS 92.5%, TN 72.3% and T-P 87.3%). It was estimated that the large amount of cost for separate sewage system and the size of area for system instruction can be reduced if the HECS is applied for CSOs treatment because the HECS is so compact and quickly. When we see the results, HECS from this study could be able to treat the pollutant quickly within a short retention time only with coagulant and polymer, which could show high applicability.

• 상하수도학회지
• /
• 제31권2호
• /
• pp.161-168
• /
• 2017

Microfiltration (MF) and Ultrafiltration (UF) membrane processes capable of producing highly purified water have been extensively applied as a pretreatment process in the wastewater reuse field with the improvement of membrane properties and resistance, development of operating protocols, and improvement of technologies of backwashing and physicochemical cleaning, and improvement of scale and antifoulants. However, despite of the development of membrane production and process technologies, fouling still remains unresolved. This study confirmed that foulants such as polysaccharides, proteins and humic substances existed in final treated effluent (secondary effluent) by fluorescence excitation emission matrix (FEEM) and fourier transform infrared spectroscopy (FTIR) analysis. In addition, when constructing ozone oxidation and coagulation processes as a hybrid process, the removal efficiency was 5.8%, 6.9%, 5.9%, and 28.2% higher than that of the single process using coagulation in turbidity, color, dissolved organic carbon (DOC), and UV254, respectively. The reversible and irreversible resistances in applying the hybrid process consisting of ozone oxidation and coagulation processes were lower than those in applying ozone oxidation and coagulation processes separately in UF membrane process. Therefore, it is considered possible to apply ozonation/coagulation as a pretreatment process for stable wastewater reuse by and then contributing to the reduction of fouling when calculating the optimal conditions for ozone oxidation and coagulation and then to applying them to membrane processes.

• Membrane and Water Treatment
• /
• 제7권6호
• /
• pp.521-537
• /
• 2016

Laboratory-scale experiments were carried out to investigate the adsorption equilibrium, the adsorption kinetics and facilitated transport of two cationic dyes (Methylene Blue (MB) and Rhodamine B (RB)) on Polymer Inclusion Membrane (D2EHPA-PIM). Different adsorption isotherms (Freundlich, Langmuir and Temkin models) as well as kinetics models indicated that the adsorption process is spontaneous and exothermic. Under the optimal conditions, the adsorption removal efficiencies reach about 93% and 97% for MB and RB respectively. Different extraction values by D2EHPA-PIM were obtained for the two cationic dyes: MB is weakly extracted at pH 2.0 (E% = 18.7%) whilst E% = 82.4% was observed for RB at the same pH. This difference was exploited in a mixture containg both the 2 cationic dyes for the selective extraction of RB at pH 2. Desorption of both dyes was achieved from the membrane by using acidic aqueous solutions and desorption ratio up to 90% was obtained. The formulas of the extracted complexes by the PIMs were, determined by the method of slopes. The dyes transport was elucidated using mass transfer analysis where in it found relatively high values of the initial flux ($J_0$) as 41.57 and $18.74{\mu}mol.m^2.s^{-1}$ for MB and RB respectively.

• Asian-Australasian Journal of Animal Sciences
• /
• 제6권1호
• /
• pp.139-145
• /
• 1993

Biogas created from animal waste is a precious energy source. A practical and successful utilization of the biogas is not easy, because there lie some difficulties in biogas production and facilities investment. In this study, the requisites for a successful biogas utilization were discussed. The production results obtained in the previous operation of anaerobic digestion plant were used for the simulation. When the slurry heating was designed for constant biogas generation, depreciation costs of the facilities amounted 1,175,000 yen per year, and biogas productions at $24.5^{\circ}C$, $30.0^{\circ}C$ and $35.5^{\circ}C$ were $16.8m^3$, $17.6m^3$ and $25.1m^3$, respectively. Removal ratios of organic matters were not so high. At $35.5^{\circ}C$, energy value of the biogas produced was estimated 125.5 Mcal per day, and the following heat loss (y Mcal/day) was brought about by the temperature difference ($X^{\circ}C$) between the digester and atmosphere; y = 0.769X - 5.375. The costs of biogas production per cow were assumed to decrease according to enlargement of feeding scale, especially on scales of more than 30 cows. On recent levels of costs and prices of energy in Japan, they were nearly equal to 2 to 3 fold of the price of municipal mixed gas when a anaerobic digester was compulsorily heated and kept at $30.0^{\circ}C$ or $35.5^{\circ}C$.

• Journal of Korean Neurosurgical Society
• /
• 제51권4호
• /
• pp.208-214
• /
• 2012

Objective : Discal cyst is rare and causes indistinguishable symptoms from lumbar disc herniation. The clinical manifestations and pathological features of discal cyst have not yet been completely known. Discal cyst has been treated with surgery or with direct intervention such as computed tomography (CT) guided aspiration and steroid injection. The purpose of this study is to evaluate the safety and efficacy of the percutaneous endoscopic surgery for lumbar discal cyst over at least 6 months follow-up. Methods: All 8 cases of discal cyst with radiculopathy were treated by percutaneous endoscopic surgery by transforaminal approach. The involved levels include L5-S1 in 1 patient, L3-4 in 2, and L4-5 in 5. The preoperative magnetic resonance imaging and 3-dimensional CT with discogram images in all cases showed a connection between the cyst and the involved intervertebral disc. Over a 6-months period, self-reported measures were assessed using an outcome questionaire that incorporated total back-related medical resource utilization and improvement of leg pain [visual analogue scale (VAS) and Macnab's criteria]. Results : All 8 patients underwent endoscopic excision of the cyst with additional partial discectomy. Seven patients obtained immediate relief of symptoms after removal of the cyst by endoscopic approach. There were no recurrent lesions during follow-up period. The mean preoperative VAS for leg pain was $8.25{\pm}0.5$. At the last examination followed longer than 6 month, the mean VAS for leg pain was $2.25{\pm}2.21$. According to MacNab' criteria, 4 patients (50%) had excellent results, 3 patients (37.5%) had good results; thus, satisfactory results were achieved in 7 patients (87.5%). However, one case had unsatisfactory result with persistent leg pain and another paresthesia. Conclusion : The radicular symptoms were remarkably improved in most patients immediately after percutaneous endoscopic cystectomy by transforaminal approach.

• Journal of Korean Neurosurgical Society
• /
• 제46권2호
• /
• pp.136-143
• /
• 2009

Objective: Remote cerebellar hemorrhage (RCH) is one of the rare complications occurring after supratentorial surgery, and its pathomechanism is poorly understood. We report 10 cases of RCH from our institution and review 154 cases from a database in order to delineate incidence, common presentation, risk factors, and outcomes of this complication. In addition, the means of prevention are discussed. Methods: We reviewed the medical records of 10 patients who experienced RCH after undergoing supratentorial surgery at our institution between 2001 and 2008. A database search in Medline revealed 154 cases of RCH in the English literature. Characteristic features were analyzed and compared. Results: There were 10 cases of RCH among 3307 supratentorial surgery cases, indicating a 0.3% incidence. All patients had characteristic imaging features of RCH, namely a streaky bleeding pattern in the superior folia of the cerebellum. Seven patients had a history of preoperative hypertension. Four cases were related to cerebral aneurysms, and other four developed after the removal of brain tumors. Cerebrospinal fluid (CSF) drainage apparatuses were installed postoperatively in all cases. Outcomes according to modified Rankin scale (mRS) were good in 7 patients, with 1 fatal case. Conclusion: RCH is a rare complication after supratentorial surgery, and the exact etiology still remains uncertain. Hypertension and perioperative loss of CSF seem positively correlated with RCH, but no single risk factor is totally responsible. Patients with RCH should be closely observed to improve their prognosis.

• Korean Chemical Engineering Research
• /
• 제44권4호
• /
• pp.382-386
• /
• 2006

볏짚은 국내에서 유용한 재생 가능한 바이오매스이다. 유동층과 char 분리 장치가 구비된 벤치 규모 급속 열분해 장치와 제올라이트 촉매를 이용하여 볏짚으로부터 바이오 오일의 생산에 대한 실험을 수행하였다. 본 연구는 제올라이트 촉매의 첨가에 따른 볏짚의 열분해 생성물의 분포와 바이오 오일의 화학적 구성을 알아보기 위한 것이다. 볏짚의 촉매 열분해 결과 무촉매 열분해에 비해 기체, char 성분은 증가하고 액체 성분은 감소하였다. 또한, 오일 중 수분이 탈산소의 영향으로 증대된 결과를 가져왔다. 촉매 열분해의 경우 오일 성분 중의 aromatics 성분이 증대되었고 발열량이 증가하였다.

• 한국전기전자재료학회논문지
• /
• 제13권9호
• /
• pp.729-734
• /
• 2000

Recently, Very Large Scale Integrated (VLSI) circuit & deep-submicron bulk Complementary Metal Oxide Semiconductor(CMOS) devices require gate electrode materials such as metal-silicide, Titanium-silicide for gate oxides. Many previous authors have researched the improvement sub-micron gate oxide quality. However, few have reported on the electrical quality and reliability on the ultra thin gate oxide. In this paper, at first, I recommand a novel shallow trench isolation structure to suppress the corner metal-oxide semiconductor field-effect transistor(MOSFET) inherent to shallow trench isolation for sub 0.1${\mu}{\textrm}{m}$ gate oxide. Different from using normal LOCOS technology deep-submicron CMOS devices using novel Shallow Trench Isolation(STI) technology have a unique"inverse narrow-channel effects"-when the channel width of the devices is scaled down, their threshold voltage is shrunk instead of increased as for the contribution of the channel edge current to the total channel current as the channel width is reduced. Secondly, Titanium silicide process clarified that fluorine contamination caused by the gate sidewall etching inhibits the silicidation reaction and accelerates agglomeration. To overcome these problems, a novel Two-step Deposited silicide(TDS) process has been developed. The key point of this process is the deposition and subsequent removal of titanium before silicidation. Based on the research, It is found that novel STI structure by the SEM, in addition to thermally stable silicide process was achieved. We also obtained the decrease threshold voltage value of the channel edge. resulting in the better improvement of the narrow channel effect. low sheet resistance and stress, and high threshold voltage. Besides, sheet resistance and stress value, rms(root mean square) by AFM were observed. On the electrical characteristics, low leakage current and trap density at the Si/SiO$_2$were confirmed by the high threshold voltage sub 0.1${\mu}{\textrm}{m}$ gate oxide.

• 대한환경공학회지
• /
• 제30권10호
• /
• pp.984-991
• /
• 2008

본 연구에서는 다공성 포화매질내에서 페놀의 제거를 위해 효소 중합반응의 적용성을 조사하였다. 페놀로 오염된 지하수의 모의실험으로 실험실 규모의 모래 충진 칼럼(ID: 4.1 cm, 충진높이: 12 cm)에 HRP와 과산화수소수를 주입하여 페놀 제거율 및 고분자 생성율에 대한 효소량(0$\sim$2 AU/mL), 이온강도(5$\sim$100 mM), pH(5$\sim$9)의 영향을 평가하였다. 페놀의 제거율은 효소량 2.0 AU/mL, 이온강도 20 mM, pH 7에서 각각 유입농도의 90% 이상을 유지하였다. 유입페놀은 다공성 매질에 축적되는 불용성 고분자와 유출되는 용해성 고분자들로 변환되었다. 최대 약 8%의 공극부피가 고분자화 반응으로부터 생산된 불용성 고분자에 의해 감소되었다.