The purpose of this study is to examine how cohesion features can be used to distinguish between essays written by Korean and NS college students. A total of 800 essays from the ICNALE (International Corpus Network of Asian Learners of English) corpus were analyzed using the newly-developed automated analysis of cohesion program, TAACO (the Tool for the Automatic Analysis of Cohesion). In order to examine whether there are statistically significant differences between NS and Korean students, a multivariate analysis of variance (MANOVA) was conducted. The multivariate test result showed that the combined cohesion indices were significantly affected by L1, indicating that Korean and NS students differed in terms of various cohesion indices. A stepwise discriminant function analysis was also carried out to characterize the nature of cohesion differences in essays between NS and Korean students. The best two predictors for distinguishing between Korean students’ essays and NS students’ essays are the overlap of function words and the use of demonstratives. Overall, NS students produced a more cohesive writing than Korean students in that they employed overlapping words, demonstratives, and lexical subordinators as a way to connect ideas across sentences. Implications of this study for English writing pedagogy are discussed.

In this paper, the performance of a synthetic fiber filter aimed at high-speed operation and dosed with different coagulants or filter aids was investigated. Without a coagulant, the filter efficiency was about 62% which was greatly enhanced when three types of coagulants namely PAC, Alum, and FeCl3 were used. Among the coagulants tested, PAC was the most effective, giving 91% filter efficiency, followed by Alum with 90%, and FeCl3 with 78%. PAC worked effectively at a very small range of dose, but Alum was relatively effective in a wide range of concentration. Compared with PAC and Alum, FeCl3 provided more or less contant efficiency regardless of its dose but gave the poorest filter efficiency. Moreover, as the inflow turbidity increased, headloss increased and the efficiency decreased at any dose and type of coagulant. The headloss recorded in this particular synthetic fiber filter is not significant as compared to that observed in typical granular filters. The recovery of solids estimated after filter cleaning was about 80% for both PAC and Alum, but poorer at 72% in the case of FeCl3 due to the heavy and large floc characteristics. The recurrence of filter efficiency verified through repetitive filter runs was found to be satisfactory.

Nanosized and aggregated Y2O3:Eu Red phosphors were prepared by template method from metal salt impregnated into crystalline cellulose. The particle size and photoluminescent property of Y2O3:Eu red phosphors were controlled by variation of the calcination temperature and time. Dispersed nanosol was also obtained from the aggregated Y2O3:Eu Red phosphor under bead mill wet process. The dispersion property of the Y2O3:Eu nanosol was optimized by controlling the bead size, bead content ratio and milling time. The median particle size (D50) of Y2O3:Eu nanosol was found to be around 100 nm, and to be below 90 nm after centrifuging. In spite of the low photoluminescent properties of Y2O3:Eu nanosol, it was observed that the photoluminescent property recovered after re-calcination. The dispersion and photoluminescent properties of Y2O3:Eu nanosol were investigated using a particle size analyzer, FE-SEM, and a fluorescence spectrometer.

분리막 생물반응조내 침지형 평막(공칭공경 0.15 ㎛, CPVC)을 사용하여 운전방식에 따른 막 오염 저감효과를 알아보았다. 또한 SMP, EPS와 같은 입자성 물질을 플록으로 형성시켜 장기운전을 가능하게 하였다. 운전방식은 기존 운전/휴지 방식과 연속적으로 처리수를 생산할 수 있도록 자체 개발한 사인파형 투과유속 연속운전(Sinusoidal flux continuous operation; SFCO)을 적용하였다. 응집제를 투여한 경우 기존 운전/휴지방식에 비하여 SFCO의 TMP는 최대 30% 미만으로 유지됨을 확인할 수 있었다.

The glucomannan content of Aloe vera gel was measured by a novel method using a bentonite suspension that floc-culates upon mixing with gels prepared by hand filleting of aloe leaf. An optimum flocculation condition was deter-mined to be Aloe vera gel diluted in the range of 2 to 5-fold and then a bentonite suspension 1% (w/v) mixed withthe gel sample in the ratio of 8:2 (v/v) to provide a mixture volume of 10mL with the length to diameter ratio of5. Under the conditions of these experiments, a rapid settling (<3 min) of more than 90% of the bentonite wasachieved only when the aloe gel sample was properly diluted. The glucomannan concentrations in various dilutedsamples with the highest settling rates were identified in the range of 195.7±21.4mg/L; thus, the results indicate thatthe glucomannan content may be determined from the dilution rate of the aloe gel sample that exhibits the highestsettling rate. This study provides a simple, rapid, and cost-effective assay for the estimation of the glucomannanlevel in raw Aloe vera gel.

Lactobacillus jensenii YW-33이 생산하는 생물응집제의 활성본체를 규명하고자 응집물질을 분리, 정제하고 그 특성을 검토하고자 하였다. 생물응집제의 활성 본체를 조사하기 위하여 배양액을 원심분리하여 균체 자체와 균체를 제거한 상등액을 비교한 결과 균체를 제거한 상등액이 86%로 높은 응집활성을 나타냈다. 또한 pronase 처리와 periodate 산화를 행한 결과 pronase로 처리한 시료는 무처리군과 비교하여 차이가 없었던

BaTiO3/epoxy composites can be applied as the dielectric materials for embedded capacitors. The effects of the degree of BaTiO3 particle agglomeration on the dielectric properties of BaTiO3/epoxy composites were investigated in the present study. The degree of particle agglomeration was controlled by the milling of the agglomerated particles. The size and content of the agglomerated BaTiO3 particles decreased with an increase in the milling time. The dielectric constants and polarizations of BaTiO3/epoxy composites abruptly decreased with the increase of the milling time. It was concluded that the dielectric constants and polarizations of BaTiO3/epoxy composites decreased as the degree of particle agglomeration decreased. The degree of agglomeration of BaTiO3 particles turned out to be a very influential factor on the dielectric properties of BaTiO3/epoxy composites.

식품 및 발효공업의 균체 제거에 이용할 수 있는 새로운 미생물 응집체를 개발할 목적으로 토양에서 분리한 Bacillus megaterium 의 응집제 생산 특성을 조사한 결과 sucrose 2.0%, NaNO_3 0.3%, tryptone 0.01%, beef extract 0.01%, MgSO_4 0.05%, CaCO_3 0.005%가 최적 배양배지로 조사되었으며 최적배지에서의 응집활성은 257.8 unit로 기초배지에 비해 응집활성이 약 161% 증가하였다. 한편 본 균주는 탄소원 및 무기염의 첨가에 의해 응집활성이 크게 영향을 받았으나 질소원의 경우 다른 성분에 비해 영향이 크지 않은 것으로 조사되어 본 균주가 생산한 응집체는 균체외 다당류의 일종인 것으로 추측된다. 또한 조정제 응집제에 대한 정색반응 결과 생산 응집제를 조정제한 후 정색반응 실험 결과는 비환원성 당으로 fructose를 함유하지 않은 다당의 일종인 것으로 추측되었다.

The use of Soluble Cutting Fluids (SCF) is essential in the development of industrial technology. However, it is difficult to decompose biologically due to its high concentrations of organic substances and nitrogen compounds, which interfere with microbial growth. Recently, Advanced Oxidation Processes are being studied both domestically and internationally. Electrolysis is highly adaptable industrial wastewater treatment because it has high removal efficiency and short processing time, regardless of the contaminant’s biodegradable nature. Accordingly, this study shows the characteristics of total nitrogen removal in SCF on the operating time, current density, and electrolytes when using aluminum in a batch-type reactor. The results are as follows: ① Under the condition of without the electrolyte when the current density was adjusted to 40 A/m2, 60 A/m2, or 80 A/m2, the respective T-N removal efficiencies were 71.7%, 80.6%, and 87.2% at 60 min. ② In the comparison for the condition of whether NaCl was added, the removal efficiency of adding NaCl (5 ~ 10 mM) was higher than non-addition at 60 min for all current densities. ③ In the comparison for the condition of whether Na2SO4 (5 ~ 10 mM) was added, the removal efficiency when adding Na2SO4 showed no significant difference compared to non-addition at 60 min for all current densities.

세계적으로 하수처리장 방류수 수질기준이 강화되고 있으며 국내 또한 하수처리장 에너지 자립율을 높이기 위해 하･페수처리장 내 고효율 혐기소화조 및 소화조 전처리 설비가 도입되면서 방류수의 수질은 향상되었다. 그러나, 농축조 및 소화조 후단에서 발생하는 반류수의 농도가 지속적으로 증가하여 하･폐수처리장 내 생물반응조 운영에 악영향을 미치고 있는 실정이다. 반류수는 발생특성상 연속적으로 발생되지 않고 간헐적･주기적으로 발생되며 슬러지 처리계통에서 배출되고 있다. 반류수 발생 시 시간 최대유량 및 농도가 수처리공정 하수유입 부하 대비 100% 이상의 부하증가를 초래하는 경우도 있어 이로 인한 생물반응조의 운영에 어려움을 겪고 있는 실정이다. 이러한 반류수 유량은 유입유량의 1~3%로 적은 양으로 발생되지만 고농도로써 수처리 공정에 충격부하를 유발하기 때문에 전체 처리효율에 악영향을 주는 것으로 알려져 있다. 또한, 질소의 농도가 높기 때문에 반류수에 의한 유입수의 질소부하 증가량은 유입 질소 부하량의 15~25% 이상을 차지한다. 이러한 반류수의 처리를 위해 생물반응조 유입 전 전처리를 통해 부하를 감소시키기 위해 응집침전 방법을 선정하였다. 이에 본 연구에서는 대구 S 하수처리장의 반류수를 대상으로 유입유량 대비 반류수의 연간 유량 및 유입 부하를 파악하였고, 고농도로 유입되는 반류수의 처리를 위해 pH, 응집제 종류, 혼화 시간 및 rpm 의 인자들을 조절하여 응집실험을 진행하였으며, CODCr, T-N, T-P, SS, NH4+의 저감효율을 도출하였다.

본 연구는 응집제 자동투입장치를 탈수기 전단에 장착하여 농축슬러지의 플록상태에 따른 고분자 응집제 주입량을 다르게 함으로써 탈수케이크의 함수율 저감 및 응집제 사용량 절감, 탈수여액의 수질개선 등 탈수특성에 미치는 영향을 평가하는데 그 목적이 있다. 응집제 자동투입장치를 B시 S하수처리장의 벨트프레스 전단에 적용한 결과 고속회전 및 응집제 분사를 통한 균일한 플록이 형성됨에 따라 기존 시스템 대비 탈수케이크 함수율 및 응집제 주입율 저감효과를 나타내었다. S하수처리장 농축슬러지(TS; Thickened sludge)에 대한 여름철, 가을철 및 겨울철의 기존 시스템 대비 응집제 자동투입장치의 최적 운전조건은 탈수케이크의 함수율 기준으로 판단해 볼 때 각각 DS-P(14%), DS-P(13%) 및 DS-P(12%)로, 이때의 탈수케이크 저감율은 25.3%, 30.7% 및 13.3%를, 고분자 응집제(P; Polymer) 저감율은 17.6%, 16.7% 및 20.0%를 각각 나타내었다. 응집제 자동투입장치의 회전속도와 유입 농축슬러지량 대비 고분자 응집제 주입율과의 상관관계를 평가한 결과 회전속도를 900~1,200 rpm의 범위 내에서 운전시 플록형성이 양호하게 나타났다.