• 환경위생공학
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• 제8권1호
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• pp.81-91
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• 1993

This paper was carried out to isolate and identify Aeromonas caviae which can degrade Sodium Dodecyl Benzene Sulfonate(SDBS) effectively. And the affecting factors for the ability of bacterial degradation were also studied. Frm October 1991 to February 1992, two hundred samples from sweage in Taegu area and Nakdong river waters in Talsung Gun area were tested. Minimal salt medium which contain SDBS only as a carbon source was used as a culture medium. The isolated new strain was identified as Aeromonas caviae Kim & Kweon. The optimal pH for SDBS degradation were 7.0 and temperature, $32^{\circ}C.$ It was taken 24 hours to degrade SDBS of 20mg/l completely under the optimal pH and temperature. And in the case of 30 mg/l of SDBS, it was taken 36 hours. The nitrogen sources were added to the minimal salt media containing 20mg/l of SDBS, and they were incubated at $32^{\circ}C$ for 14 hours. 86.9% SDBS were degraded after addition of 0.03% peptone as a organic nitrogen source. And 70.5% SDBS after addition of 0.05% ammonium sulfate as a inorganic nitrogen source. In the case of metal compounds(0.015%), the degradation rate for SDBS were 3.5 fold increased in the media containing magnesium chloride and calcium chloride than in the media that were not containing these metal compounds. And where the media containing magnesium chloride was 0.05%, the degradation rate was 65.8%. And above 0.3% NaCI, the degradation rate was decreased slowly.

• KSBB Journal
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• 제16권1호
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• pp.61-65
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• 2001

BTX를 배출하는 지역에서 얻어진 슬러지를 적절한 배지에 3개월 간 적응시킨 결과, benzene과 toluene을 빠르게 분해하는 MY컨소시엄와 p-, m-, o-xylene을 빠르게 분해하는 MA컨소시엄을 획득하였다. 균주의 동정결과 MA 및 MA컨소시엄의 주된 균주는 Rhodococcus ruber DSM 43338T과 Rhodococcus sp.로 밝혀졌다. BTX 단일성분의 분해속도 측정결과 benzene > toluene > o-xylene > p-xylene > m-xylene의 순으로 분해가 일어났다. MY 및 MY컨소시엄으 동시배양을 이용한 2-5종의 복합 BTX의 분해실험결과 대부분의 경우 108시간내에 완전히 분해되었으며, 각 혼합물의 조성에 따라 촉진 및 방해작용을 나타내었다. 분 연구에서 획득한 2종의 미생물컨소시엄은 BTX의 생물학적 처리에 매우 유용하게 사용될 수 있을 것으로 사료된다.

• 한국환경농학회지
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• 제17권3호
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• pp.234-238
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• 1998

Anaerobic degradation characteristics of dewatered liquid of household food waste including methane conversion efficiency and degradation kinetics were studied in an anaerobic batch reactor of 5 L volume. The ultimate methane production for dewatered liquid of household food waste tested was over 0.31L $CH_4/L{\cdot}dewatered$ liquid of household food waste. The kinetic constant of dewatered liquid of household food waste tested was $0.223d^{-1}/L$. The kinetic behavior of anaerobic degradation was described as a first order series reaction. The determinant of rate-limiting step(DR) that is balanced out from the rates of reaction steps was defined by the logarithmic difference of the maximum acidification rate and the maximum methanation rate. Anaerobic degradation characteristics of organic materials were evaluated by the value of DR. The DR of dewatered liquid of household food waste tested was 1.17.

• 대한화학회지
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• 제17권4호
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• pp.298-305
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• 1973

Roll을 사용한 mastication에 의한 polystyrene(단독시와 rubber와의 blend시)의 기계적 분열에 대하여 검토한 결과는 다음과 같다. 1) Polystyrene 단독시의 기계적 분열속도는 Goto가 밝힌 중합도$(P_t-P_{\infty})$에 관하여 2차인 다음식에 적합함을 알았다. $-\frac{dP_t}{dt} = k_s(P_t-P_{\infty})^2$2 2)Polystyrene-rubber (SBR, BR) blend계에서 polystyrene성분의 분열은 단독시와 비스하게 일어났다. 3)본 실험 조건하에서 polystyrene-rubber (SBR, BR) blend계에서, polystyrene성분의 분열속도도 단독시와 같이 상기한 2차식에 근사적으로 적합됨을 알았다.

• 한국대기환경학회지
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• 제18권3호
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• pp.223-230
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• 2002

Titania photocatalytic oxidation reactors were studied to investigate degradation efficiencies of hydrocarbons. In general, it is well known phenomena that thin layered titania oxidizes most of hydrocarbons to carbon dioxide and water under UV light. In this study, degradation efficiencies were measured due to changes in reactor structures, UV sources, the number of titania coatings, and various hydrocarbon chemicals. It was proven that gas degradation efficiencies are related to such factors as UV transmittance of coating substance, collision area of surface, and gas flow rate. For packing type annular reactor, about 98% degradation efficiency was achieved for achieved for propylene of 500 ppm level at a flow rate of 100 ml/min. Several gases were also tested for double-coated titania thin film under the condition of continuous flow of 100 ml/min and 365 nm UV source. It was shown that degradation efficiencies were decreasing in the order: $C_3$ $H_{6}$, n-C$_4$ $H_{10}$, $C_2$ $H_4$, $C_2$ $H_2$, $C_{6}$ $H_{6}$ and $C_2$ $H_{6}$./. 6/./.

• Journal of Pharmaceutical Investigation
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• 제2권1호
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• pp.52-57
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• 1972

There are many reports on the stability of drugs in powders and various dosage forms. The author studied on the stability of ascorbic acid mixed with talcs. From the result of this experiment, it was considered that talcs markedly accelerated oxidative degredation of ascorbic acid in powders and the acceleration rate depends on the varieties of crude talcs. Iron salts seem to be the principal factor influencing the degradation of ascorbic acid Degradation rate of ascorbic acid mixed with purified talc is significantly slower than that with the crnde talcs. The more the concetration of ascorbic acid is diluted, the faster the degradation rate and degredation rate of Ascorbic acid is the function of tme.

• Journal of Communications and Networks
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• 제1권2호
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• pp.134-142
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• 1999

We have developed fully functional Video Server and Client applications which can transmit, receive, decompress and display compressed video over various networks. Our video trans-port allows dynamic rate control feedback, loss detection, and repair requests from Clients to the Server. Our experiments show how feedvack-before-degradation scheme for rate adaptation maintains good display frame-rate for video playback. We show how the playback degradation(reduction in display frame-rate) oc-curs and what happens if corrective measures are not taken to im-prove the situation. The degradation is attributed to the increased internal kernel buffering which consumes scarce CPU resources. We demontrate with our experimental results that ServerNet, with improved hardware delivery guarantees, can significantly reduce host CPU resource consumption while serving video streams. We present the maximum number of streams which can be served for each of ATM and ServerNet interconnects. The appropriate user-level packet size for the video server are also determined for each case.

• 한국잡초학회지
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• 제17권2호
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• pp.214-219
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• 1997

토양중에 있어서 제초제(除草劑) alachlor 분해(分解)에 미치는 퇴비(堆肥), 화학(化學) 비료(肥料), 중금속(重金屬), 합성(合成) 세제(洗劑)의 영향(影響)에 대하여 연구한 결과를 요약하면 다음과 같다. 토양(土壤)중 alachlor는 1차 반응식(反應式)에 따라 분해(分解)되었으며 반감기(半減期)는 6.4일이었다. 퇴비(堆肥) 첨가(添加)는 alachlor의 분해(分解)를 촉진(促進)시켰다. 화학(化學) 비료(肥料)중 질소와 칼리 특히 질소 첨가에 의하여 alachlor의 분해(分解)가 촉진(促進)되었다. 토양중 alachlor의 분해(分解)는 중금속(重金屬)에 의하여 억제(抑制)되었으며 Cd, Cr, Ni, Zn, Cu 첨가(添加) 토양(土壤)중 반감기(半減期)는 각각 11.0, 8.3, 7.9, 7.2, 6.7일이었다. 합성(合成) 세제(洗劑) 첨가(添加) 또한 alachlor의 분해(分解)를 억제(抑制)시켰으며 반감기는 7.5일이었다. 각종(各種) 물질(物質)을 첨가(添加)한 토양(土壤)중에서 alachlor의 분해율(分解率)은 토양(土壤)의 microbial biomass나 호흡율(呼吸率)과 높은 정(正)의 상관(相關) 관계(關係)를 보여 각종(各種) 첨가(添加) 물질(物質)이 alachlor의 분해(分解)를 촉진(促進)혹은 억제(抑制)하는 것은 이들 첨가(添加) 물질(物質)이 분해(分解) 미생물(微生物)의 생육(生育)을 촉진(促進)또는 억제(抑制)하였기 때문으로 판단되었다.

• 한국환경과학회지
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• 제19권9호
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• pp.1143-1152
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• 2010

The purpose of this study is to degradation of Rhodamine B (RhB, dye) and N, N-Dimethyl-4-nitrosoaniline (RNO, indicator of the electro-generation of OH radical) in solution using boron doped diamond (BDD) electrode. The effects of applied current (0.2~1.0 A), electrolyte type (NaCl, KCl, and $Na_2SO_4$) and electrolyte concentration (0.5~3.0 g/L), solution pH (3~11) and air flow rate (0~4 L/min) were evaluated. Experimental results showed that RhB and RNO removal tendencies appeared with the almost similar thing, except of current. Optimum current for RhB degradation was 0.6 A, however, RNO degradations was increased with increase of applied current. The RhB and RNO degradation of Cl type electrolyte were higher than that of the sulfate type. The RhB and RNO degradation were increased with increase of NaCl concentration and optimum NaCl dosage was 2.5 g/L. The RhB and RNO concentrations were not influenced by pH under pH 7. Optimum air flow rate for the oxidants generation and RhB and RNO degradation were 2 L/min. Initial removal rate of electrolysis process was expressed Langmuir - Hinshelwood equation, which is used to express the initial removal rate of UV/$TiO_$2 process.

• 자원리싸이클링
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• 제18권6호
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• pp.10-17
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• 2009

과열 증기를 이용하여 생활 폐기물내 유기성 성분의 분해를 수행하고 폐기물의 특성 및 반응 시간이 폐기물의 분해율에 미치는 영향을 살펴보았다. 과열 증기를 이용한 분해 후 음식 및 폐지와 같은 생분해성 유기 성분은 쉽게 분해되었고 생분해성 유기 성분중 나무와 석유계 유기성 성분인 플라스틱, 금속과 같은 무기성 성분이 분해되지 않은 상태로 남아 쉽게 분리가 가능한 상태를 형성하였다. 입자의 크기 변화를 살펴본 결과 폐기물 내 생분해성 유기 성분이 적을수록 짧은 반응 시간에도 높은 입자 크기 감소를 보였으며 반응 시간이 60분 이상에서 최대 90% 이상의 입도 감소를 나타내었다.