• Proceedings of the Korean Environmental Sciences Society Conference
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• 2006.05a
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• pp.304-306
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• 2006

본 연구에서는 하수슬러지의 감량화 방안으로 초음파-알칼리 전처리를 통한 하수슬러지의 가용화 특성과 전처리된 하수슬러지의 비메탄활성도(SMA) 실험을 통한 메탄가스 발생 특성을 살펴본 결과 다음과 같은 결론을 얻을 수 있었다. 하수슬러지의 전처리에서 초음파와 알칼리의 단독 전처리보다는 초음파-알칼리 전처리의 경우, 또한 단일주파수 초음파보다는 이중주파수 초음파의 경우 SCOD 가용화율과 처리시간에 있어 더 효과적임을 알 수 있었다. 알칼리(40meq/L NaOH), 초음파(15, 20, 15+20kHz), 알칼리와 초음파 전처리시(15, 20, 15+20kHz with 40meq/L NaOH)시 반응시간 45분에서 하수슬러지의 세포파괴도가 가장 높게 나타난 것은 알칼리(40meq/L NaOH)와 이중주파수 초음파 15+20kHz 전처리로 조사되었으며, 이때 세포파괴도는 98.7%로 나타났다.

• Journal of the Korea Organic Resources Recycling Association
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• v.17 no.1
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• pp.96-102
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• 2009

The effect of ultrasonic and alkaline pre-treatments on waste activated sludge (WAS) disintegration was investigated for improved anaerobic digestion. As WAS was treated by either methods, longer capillary suction time (CST) was required due to the break-up of cell walls, and its supernatant demonstrated increase in soluble chemical oxygen demand (SCOD), protein content and turbidity. Ultrasonic process combined with alkaline pre-treatment demonstrated higher SCOD and protein content in the supernatant as compared with ultrasonic pre-treatment only. However, the degree of disintegration (DDCOD) of WAS decreased with increasing solid concentration as both WAS disintegration methods employed simultaneously.

• Journal of Korean Society of Environmental Engineers
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• v.29 no.1
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• pp.98-105
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• 2007

The objectives of this study were to demonstrate that enhanced anaerobic digestion could be achieved by adopting ultrasonic cavitation pretreatment on the basis of the biogas production and to compare the simulation results of ADM1 (Anaerobic Digestion Model No. 1) with results of the experimentally operated digester the ultrasonic pretreatment of sewage sludge showed the hindered effect on the dewaterbility and the increase of SCOD production. In this study, four sets of lab-scale anaerobic digester were operated with untreated(control), 30 min, 60 min and 90 min ultrasonic pretreated sludge. TCOD removal efficiencies in digesters of control, 30, 60, 90 min sonicated sludge were 31.9%, 37.9, 38.5% and42.2%, and 75 removal were 15.9%, 20.8%, 21.5%, 24.1% respectively. Also more biogas was produced gradually with the increased sludge loading and the pretreatment time. Overall the simulation results had a correspondence tendency with the experimental efficiencies.

• Journal of the Korea Organic Resources Recycling Association
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• v.26 no.2
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• pp.53-63
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• 2018

The hydrolysis of organic solid waste, such as sludge, is the rate-limiting step of the anaerobic digestion. The longer rate-limiting step lead to decrease of treatment efficiency and increase hydraulic retention time and anaerobic digester. Therefore, the pre-treatment has been applied for accelerating the hydrolysis step. This study was investigated the effects of pre-treatment of waste activated sludge using ultrasonic and alkaline integrated treatment simultaneously. The results showed the cumulative methane production and the methane production rate increased while the lag phase decreased. Therefore ultrasonic and alkaline integrated pre-treatment of waste activated sludge resulted in acceleration of hydrolysis step in anaerobic digestion.

• Proceedings of the Korea Information Processing Society Conference
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• 2005.05a
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• pp.1623-1626
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• 2005

초음파 영상 기법은 장기, 연조직, 혈류를 검사하는데 쓰이는 영상 진단법이다. 초음파 장비를 통해 얻어진 초음파 볼륨 데이터는 장비 특성상 많은 잡음(speckle noise)을 포함하기 때문에, 깨끗한 영상을 얻기 위해서는 잡음 필터링(noise filtering)이 필요하다. 그런데, 볼륨 데이터 모든 영역에 대해 잡음 필터링을 적용할 경우 전처리 시간이 길어져 실시간으로 초음파 볼륨 데이터를 렌더링하기 어렵다. 본 논문에서는 실시간으로 입력되는 초음파 볼륨 데이터를 가시화 하기위하여 전처리 시간 없이 잡음을 제거하는 방법을 제안한다. 전처리 시간에 전체 볼륨 데이터에 대해 잡음 필터링을 적용하지 않고, 영상을 생성하는 동안 참조되는 복셀(voxel)에 대해서만 잡음 필터를 적용하여 얻은 값을 사용한다. 이때 필터링에 소요되는 시간을 최소화하기 위해 가장 단순한 평균화 필터를 사용한다. 그리고 복셀에 적용되는 3차원 필터를 3단계의 1차원 필터 연산 단계로 분할 한 후, 각 단계별 연산을 거친 복셀들에 대해서는 다시 연산을 하지 않도록 하여 중복을 피한다. 이를 통해 전처리 시간 없이 기존 방법과 동일한 화질을 유지하는 최종 영상을 만들어 낸다.

• Journal of the Korea Organic Resources Recycling Association
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• v.16 no.3
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• pp.83-90
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• 2008

The ultrasonic pre-treatment of sewage sludge (SS) was investigated to increase soluble organic material and to improve anaerobic biodegradability. Ultrasonic disintegration of SS increased the amount of soluble chemical oxygen demand (SCOD), protein and carbohydrate concentrations whereas particle size decreased due to the break-up of cell walls. In terms of anaerobic biodegradability, ultrasonic pre-treatment enhanced the anaerobic biodegradation of SS, leading to the methane gas production improvement. Biochemical methane potential (BMP) of SS was 211.3 ml $CH_4/gVS$ whereas BMP after ultrasonic pre-treatment was 294.3 ml $CH_4/gVS$. The improvement in BMP for SS treated with ultrasonic disintegration was as high as 40 %. This result indicated that disintegration of SS was efficient for enhancing anaerobic biodegradability.

• Journal of the Korean GEO-environmental Society
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• v.15 no.10
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• pp.15-21
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• 2014

In this study, biochemical methane potential test was conducted to estimate ultimate methane and carbon dioxide yield for anaerobic digestion and pretreatment with sewage sludge cake. Two of 0.2 % TS of sewage sludge cakes were treated with 5M NaOH or sonication of 0.51 W/mL during 30 min respectively. Another sample was treated simultaneously with NaOH and sonication in same condition. Then, initial soluble COD increased from 33.1 mg/L to 494 mg/L. After BMP test, methane production ranged from 3.12 and 84.2 mL $CH_4$ per g of Volatile Solid (VS) and 9.2 and 13.5 mL $CO_2$ per g of Volatile Solid (VS) for carbon dioxide. In other tests, injection of nutrient media or sludge supernatant produced 73.1 and 73.8 mL $CH_4$ per g of Volatile Solid (VS) and 11.2 and 13.6 mL $CO_2$ per g of Volatile Solid (VS) respectively. When BMP test finished, 62 % of initial volatile solids decreased to 33.8~45.4 %. Simultaneous pretreatment increased soluble COD, reduction rate of volatile solids and digestion efficiency than those for alkaline and ultrasonic pretreatment.

• Journal of Radiation Protection and Research
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• v.40 no.2
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• pp.101-109
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• 2015

Alpha spectrometry is typically used for the assessment of uranium particle concentrations and its accuracy can be directly related to the accuracy in which the radiochemical pre-treatment is conducted. Ashing and alkali fusion methods are typically used but the ashing method requires longer analysis time and the alkali fusion method is extremely costly. Therefore, a new pre-treatment method using ultrasonic cleaning was developed and its experimental result was compared against the two conventional methods in terms of pre-treatment time, convenience, cost, and recovery rate of a target material. The results that were obtained by the conventional methods(ashing and alkali fusion) and the new method were compared. Consequently, even though the shorter pre-treatment time was required, the new technique showed almost same recovery rate comparing with two conventional methods. The new method was also featured by its relatively lower cost and a simpler process than two conventional methods.

• Journal of Korean Society of Environmental Engineers
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• v.22 no.5
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• pp.849-859
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• 2000

This study was conducted to identify the characteristics of methane fermentation and lysis effects of pre-treated microalgae. Chemical compositions of microalgae showed that the VS(volatile solid) was 86.1% of TS(total solid), and the protein was 63.5% of VS. These values were higher than those of activated sludge. The cell lysis test of raw microalgae biomass was conducted by many physicochemical methods. presenting that the degree of cell lysis was affected by following order: ultrasonic(100min.), alkali(pH 13), ultrasonic(10min), thermal($120^{\circ}C$), thermal($50^{\circ}C$), and acidic(pH 3) treatment. Methane fermentation with many pre-treated samples was performed, showing that the concentration of acetic acid was the highest. followed by propionic acid, butylic acid and valerie acid among all VFA(volatile fattic acid). In methane production. ultrasonic samples were only more effective than untreated one in total gas and methane productivity. but other samples were less effective. Especially. the alkalic sample had an inhibitation effect on methanogens.

• Proceedings of the Korean Vacuum Society Conference
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• 2010.02a
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• pp.199-199
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• 2010

XRR(X-ray reflectometry)은 나노 스케일 박막의 두께를 측정하는 유망한 도구로 인식되고 있고, XRR측정 결과의 신뢰성을 향상시키기 위하여 많은 연구가 이루어지고 있다. 본 연구에서는 나노 스케일 박막 두께의 정확한 측정을 위해 Si기판 위에 성장시킨 $HfO_2$, $Al_2O_3$, $Ta_2O_5$의 산화물 박막에 대하여 여러 가지 전처리 조건을 변화시켜 조건에 따른 반사율 곡선의 변화와 분석 결과를 살펴보았다. 샘플의 전처리에는 acetone, sulfuric acid, methanol, 초음파세척기를 이용하였고, 전처리가 끝난 후 샘플에 남아있는 수분기를 제거하기 위하여 약 $150^{\circ}C$의 온도로 가열 후 측정비교 분석하였다. 전처리 시 solution과 시간 등의 전처리 조건이 변화함에 따라 X-선 반사율 곡선의 변화가 있음을 알 수 있었고, 이에 따라 XRR 측정 분석 시 두께에 영향을 받았으며, TEM과 XPS를 이용하여 전처리 영향에 대하여 비교 분석 하였다. 이번 연구를 통하여 전처리 방법에 따라 XRR 측정에 정확성을 향상 시킬 수 있는 있는 것으로 보여진다.