• Applied Chemistry for Engineering
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• v.16 no.5
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• pp.712-718
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• 2005

This research was conducted to evaluate the effect of recycled-water addition on the treatment of coar tar-contaminated soil with slurry phase bioreactor. A bench-scale slurry phase bioreactor was maintained to optimize the microbial growth. Silty loam soil was used for this research. Concentrations of coal tar and 14 target PAHs (Polyunclear Aromatic Hydrocarbons) in the soil were determined with gas chromatography. Addition of recycled-water to slurry phase bioreactor was not significantly increased the removal efficiency of 2000 mg coar tar/kg. However, it significantly increased the removal efficiency of 20000 mg coar tar/kg. In 20000 mg coar tar/kg, the first order kinetic constant and the removal efficiency of the reactor with recycled-water addition were 2.5 and 2.0 times higher than those of the reactor without recycled- water addition. Coar tar in the slurry phase bioreactor was removed in 3.8~16.0% by vaporization and biodegraded in 84.0~96.2%. Removal efficiency of 3-ring compounds was high as 92.2~99.7% in the case of recycled-water addition. However, removal efficiencies of 3 and 4-ring compounds were low as 0~30%.

• Journal of Soil and Groundwater Environment
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• v.14 no.2
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• pp.33-44
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• 2009

The objective of the study was to develop a hybrid technology integrating biological and physicochemical technologies to efficiently remediate arsenic contaminated lands such as abandoned mine area. The tailing soil samples contaminated with As at a high level were obtained from Songchon abandoned mine, and the content of arsenic and heavy metals as well as physicochemical properties and mineral composition were investigated. In addition, two sets of sequential extraction methods were applied to analyze chemical speciations of arsenic and heavy metals to expect their leachability and mobility in geoenvironment. Based on these geochemical data of arsenic and heavy metal contaminants, column-type experiments on the bioleaching of arsenic were undertaken. Subsequently, experiments on the hybrid process incorporating bioleaching and electrokinetics were accomplished and its removal efficiency of arsenic was compared with that of the individual electrokinetic process. With the results, finally, the feasibilty of the hybrid technnology was evaluated. The arsenic removal efficiencies of the individual electrokinetic process (44 days) and the hybrid process incorporating bioleaching (28 days) and electrokinetics (16 dyas) were measured 57.8% and 64.5%, respectively, when both two processes were operated in an identical condition. On the contrary, the arsenic removal efficiency during the bioleaching process (28 days) appeared relatively lower (11.8%), and the result indicates that the bioleaching process enhanced the efficacy of the electrokinetic process as a result of mobilization of arsenic rather than removed arsenic by itself. In particular, the arsenic removal rate of the electrokinetics integrated with bioleaching was observed over than 2 times larger than that obtained by the electrokinetics alone. From the results of the study, if the bioleaching which is considered a relatively economic process is applied sufficiently prior to electrokinetics, the removal efficiency and rate of arsenic can be significantly improved. Consequently, the study proves the feasibility of the hybrid process integrating both technologies.

• Korean Journal of Environmental Biology
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• v.38 no.1
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• pp.82-92
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• 2020

Since swine wastewater contains high concentrations of nutrients and heavy metals, it deteriorates water quality when discharged. Compared to conventional methods, bioremediation can be a promising method for its treatment. Specifically, microalgae have the potential to remove these pollutants. In this study, the removal of nutrients (nitrogen (N) and phosphorus (P)) and heavy metals (copper (Cu) and zinc (Zn)) from swine wastewater by Ankistrodesmus bibraianus was evaluated and the organism's optimal growth conditions were investigated. The optimal growth conditions were established at 28℃, pH 7, and light and dark cycles of 14:10 h. The removal efficiencies of N and P by a single treatment (500, 1,000, 5,000, and 10,000 mg L^-1) ranged from 22.9 to 80.6% and from 11.9 to 50.0%, respectively. The removal efficiencies of N and P in the binary treatments ranged from 16.4 to 58.3% and from 7.80 to 49.8%, respectively. The removal efficiencies of Cu and Zn by a single treatment(10, 30, and 50 mg L^-1) ranged from 15.5 to 81.5% and from 6.28 to 34.3%, respectively. Similarly, the removal efficiencies of Cu and Zn in the binary treatments ranged from 16.7 to 74.5% and from 5.58 to 27.5%, respectively. In addition, the study showed the optimal growth conditions for microalgae and the removal efficiency of nutrients (N and P) and heavy metals (Cu and Zn), which could be applied to swine wastewater. Based on the results in this study, it appears that Ankistrodesmus bibraianus could be used for the removal of nutrients and heavy metals present in swine wastewater.

• Proceedings of the Korean Nuclear Society Conference
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• 1998.05b
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• pp.409-414
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• 1998

5 년간의 기술실증 및 안전성 검토를 거쳐 한국원자력연구소내 실증소각시설을 자체발생 가연성 $\beta$/${\gamma}$폐기물을 소각하는 시설로 인허가를 얻었다. 동위원소포함 모의폐기물 및 원전발생 가연성폐기물 실증소각 결과에 기준을 두고 연간 배출오염원 및 가상 사고시의 방사학적 위해성을 평가하여 저준위 폐기물을 부지내에서 소각처리할 때 그 위해성은 무시할 수 있을 것으로 미미함 을 확인하였다. 실증시험으로 주된 배출 방사선원은 고온의 소각로에서 휘발성이 크고 저준위 폐기물내 농도가 큰 반휘발성 Cs-137 및 Cs-134로, 발전소 가연성폐기물과 같은 핵종조성을 가진 0.109 mCi/kg 의 소각시 Cs-137 및 Cs-134의 배출농도가 공기중허용농도의 10%를 약간 상회하는 것으로 평가되었다. 비방사성 CsCI을 이용한 시험소각을 통하여 사용되는 저온배기체처리계통 에서의 휘발된 Cs의 배기체 냉각시 입자화 및 제거특성을 고찰한 결과 휘발된 기체상 Cs성분은 건식배기체 냉각공정을 거치면서 대부분 마이크론 크기이하의 입자로 생성되지만 5% 미만이 전이영역 크기에 분포하여 주여과장치인 여과포집진기에서 제거효율이 99.9% 이상이었다.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2005.11a
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• pp.47-50
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• 2005

본 논문에서는 인터넷 스트리밍 및 모바일 응용 등에서 요구되는 저 비트율 비디오를 위한 효과적인 후처리 기법을 제안한다. 블록기반 압축영상의 특성상 낮은 비트율에서는 블록킹 현상과 같은 화질열화가 불가피하다. 이러한 블록기반 압축영상의 블록킹 현상에 대하여 본 논문에서 제안한 디블록킹 기법은 블록 경계 주변의 특성에 따라 필터링 모드를 달리 적용하여 효율적으로 블록킹 현상을 제거함으로서 주관적, 객관적 화질을 향상시킨다. 제안한 알고리즘에서는 모드 선택의 정확성을 높이기 위하여 저역통과필터를 이용한 간단한 전처리 과정을 거치도록 하고, 또한 영상의 실제 에지와 블록킹 현상을 구분하기 위하여 3가지 모드를 도입하며, 이를 통해 필터링에 의한 실제 에지 부분의 화질열화를 방지하도록 한다. 마지막으로 corner outlier와 같은 특수한 artifact의 제거를 위해 별도의 모드를 추가한다. 실험에서는 MPEG-4로 복호된 영상에 대하여 제안한 필터를 적용하고, 최근 표준화가 완료된 H.264의 루프필터 및 최근 발표된 저 비트율 비디오에 대한 후처리 기법과의 비교실험을 통하여 제안된 방법의 성능을 평가한다.

• Proceedings of the Korean Information Science Society Conference
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• 1998.10b
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• pp.123-125
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• 1998

지리 정보 시스템이서 다중 공간 조인과 같은 많은 기하 계산을 필요로 하는 질의를 처리하기 위해서는 질의에 대한 병렬화 작업을 통해 실행 시간을 최소화 하는 것이 필수적이다. 다중 공간 조인은 정제에서 많은 시간을 소비하므로 여과와 정제를 분리하여 각각을 수행하는 것이 정제 시간을 단축하게 되고 따라서 좋은 성능을 나타낼 수 있다. 그러므로 다중 공간 조인을 병렬화 하기 위해서는 다중 공간 여과와 정제 각각에 대해 병렬 실행 계획을 세우는 것이 중요하다. 이 논문에서는 우선적으로 병렬 공간 여과를 수행하기 위한 두가지 알고리즘, 즉 blush tree을 사용한 다중 공간 여과와 pipelining을 사용한 다중 공간 여과의 병렬화를 비교한다. 그리고, 다중 공간 여과의 결과로서 생성되는 중간 결과 테이블에서 데이터의 중복에 따라 정제 성능의 저하가 발생되는데, 이를 효율적으로 제거하기 위한 두가지 그래프 생성 알고리즘을 제안하고 이를 비교한다. 그리고, 생성된 그래프에서 병렬 정제를 수행하기 위한 여러 가지 분할 알고리즘을 제안하고 이를 비교 평가한다. 이런 일련의 작업을 통해 우수한 성능의 병렬 다중 공간 조인 방법을 제안하고 성능 평가를 통해 최적의 병렬 수행 방법을 도출한다.

• Journal of Korean Society of Environmental Engineers
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• v.27 no.1
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• pp.109-114
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• 2005

The objective of this study is to investigate the possibility for water treatment, and to evaluate the efficiency of simultaneous removal of ammonium and nitrate by the surface modified zeocarbon. The surface modification was done by acid treatment using HCl. As a result of modification, strength of the modified zeocarbon was enhanced about 62% higher than that of in original one. This indicates that the modified zeocarbon was suitable for the application of water treatment. In the removal experiments of ammonium and nitrate, the removal efficiency showed about two times higher in the modified zeocarbon and the dependences of pH and temperature were found to be minimized. This indicates that the modified zeocarbon was effective for simultaneous removal of ammonium and nitrate from aqueous solution. Consequently, our results could be used as basic data to design of one-stage ammonium/nitrate simultaneous removal system.

• Clean Technology
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• v.24 no.3
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• pp.157-165
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• 2018

In this study, the removal of $Si_3N_4$ particles from the surface of a silicon wafer was investigated by using supercritical carbon dioxide, the IPA co-solvent and cleaning additive chemicals. First, the solubility of several surfactants and binders in supercritical carbon dioxide solubility and particle dispersibility in the binders were evaluated in order to confirm their suitability for the supercritical cleaning process. Particle removal experiments were carried out with adjusting various process parameters and reaction conditions. The surfactants used in the experiment showed little particle removal effect, producing secondary contamination on the surface of wafers. On the other hand, 5 wt% (with respect to $scCO_2$) of the cleaning additive mixture of trimethyl phosphate, IPA, and trace HF resulted in 85% of particle removal efficiency after $scCO_2$ flowing for 4 minutes at $50^{\circ}C$, 2000 psi, and the flow rate of $15mL\;min^{-1}$.

• Journal of the Korean Geophysical Society
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• v.2 no.2
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• pp.143-152
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• 1999

We have studied a denoising technique involving wavelet transform for improving the quality of geophysical data during the preprocessing stage. To assess the effectiveness of this technique, we have made synthetic data contaminated by random noises and compared the results of denoising with those obtained by conventional low-pass filtering. The low-pass filtering of the sinusoidal signal having a sharp discontinuity between the first and last sample values shows apparent errors related to Gibbs' phenomena. For the case of bump signal, the low-pass filtering induces maximum errors on peak values by removing some high-frequency components of signal itself. The wavelet transform technique, however, denoises these signals with much less adverse effects owing to its pertinent properties on locality of wavelet and easy discrimination of noise and signal in the wavelet domain. The field data of gravity tide are denoised by using soft threshold, which shrinked all the wavelet coefficients toward the origin, and the G-factor is determined by comparing the denoised data and theoretical data.

• The KIPS Transactions:PartB
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• v.15B no.1
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• pp.1-8
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• 2008

Generally, moving objects in surveillance video are extracted by background subtraction or frame difference method. However, moving cast shadows on object distort extracted figures which cause serious detection problems. Especially, analyzing vehicle information in video frames from a fixed surveillance camera on road, we obtain inaccurate results by shadow which vehicle causes. So, Shadow Elimination is essential to extract right objects from frames in surveillance video. And we use shadow removal algorithm for vehicle classification. In our paper, as we suppress moving cast shadow in object, we efficiently discriminate vehicle types. After we fit new object of shadow-removed object as three dimension object, we use extracted attributes for supervised learning to classify vehicle types. In experiment, we use 3 learning methods {IBL, C4.5, NN(Neural Network)} so that we evaluate the result of vehicle classification by shadow elimination.