• 한국건축시공학회지
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• 제18권1호
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• pp.25-31
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• 2018

본 연구는 순환유동층보일러(CFBC)에서 발생되는 바닥재와 비산재를 활용한 저강도 고유동 채움재를 개발하였다. CFBC비산재(CFBC-F) 와 CFBC바닥재(CFBC-B)는 불규칙한 입자 형상을 가지고 있는 것과 유해성 분석결과 환경적으로 안정한 것을 확인하였다. CFBC-F가 첨가될 경우 단위수량이 증가하였다. 길이변화율은 기건양생 조건에서는 -0.05~-0.50% 범위의 수축이 발생하였으며, 밀봉양생 조건에서는 0.1~0.6%의 범위의 팽창이 발생하였다. 압축강도는 밀봉양생 조건에서는 장기적으로 수화반응을 진행할 수 있는 충분한 수분이 남아 있어 기건양생 조건 대비 압축강도가 증가 하는 것을 확인하였다. 본 연구에서 도출된 결과는 저강도 고유동 채움재 개발 및 CFBC 석탄재 활용에 있어 도움이 될 것이라 생각된다.

• 분석과학
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• 제10권1호
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• pp.66-74
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• 1997

지름 2.54cm, 길이 10cm인 유리관에 tyrosinase(EC. 1.14.18.1)를 입자의 크기 $550{\mu}m$인 탄소에 고정시켜 충진하고, 페놀과 산소를 기질로 사용하여 tyrosinase의 반응 특성을 조사하기 위해 axial dispersion 모델을 제안하였다. 본 논문에서 페놀의 농도는 55.5mM로 고정시키고 산소(2.7ppm, 5.4ppm, 그리고 9.5ppm)와 유속 (1~3mL/s)을 변화시키면서 탄소에 고정된 tyrosinase의 반응을 관찰하였다. 또한, Damkolher수를 계산하고 분산 특성과 식으로부터 효소반응 속도 및 분산의 영향을 예측하기 위해 수치적 해석을 하였다. 연구 결과 물질저항은 주로 외부 전달과 내부확산이었으며, 제안된 모델에서 Biot수는 64.25였다. 페놀은 1.0mL/s 정도의 느린 속도에서 산소의 농도가 높을수록 높은 전환율을 나타내었다. 한편, axial dispersion 모델과 plug flow 모델의 비교에서는 모두 같은 전환율을 나타내어 axial dispersion 모델이 반응속도와 무관함을 알 수 있었다.

• Journal of the Korean Wood Science and Technology
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• 제37권1호
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• pp.94-104
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• 2009

본 연구는 폐바이오매스로서 활엽수(hardwood, HW)톱밥, 침엽수(softwood, SW)톱밥, 산야초류(grass) 등 3종의 발효재료를 이용, 3종의 나선형 열교환기와 1종의 평판형 열교환기를 제작하여 발효과정에서 생산되는 발효열을 가장 효율적으로 회수할 수 있는 발효열 교환장치 개발을 위하여 실시하였다. 본 연구에서는 다양한 바이오매스재료의 적절한 원료 배합을 통한 발열 및 열교환 특성을 조사하고 실제 농가에 설치 및 해체가 용이한 열교환기를 개발하였으며, 그 결과를 요약하면 다음과 같다. 나선형 열교환기를 사용한 발효열 실험에서 활엽수톱밥 및 침엽수 : 활엽수톱밥(50 : 50) 처리보다는 활엽수톱밥 : 산야초(90 : 10)의 발효가 약 3개월간의 긴 발열기간을 나타냈으며, 발효상을 통과한 물의 온도를 100일간 측정한 결과, 중앙부가 $64.5{\sim}76.5^{\circ}C$로 매우 높았고, 물탱크 온도는 $33{\sim}48^{\circ}C$ 범위였으며, 출구의 수온은 $33{\sim}44^{\circ}C$로서 4~5인 기준의 가정용 온수공급이 가능함이 확인되었다. 수행한 4종의 열교환기 실험 결과, 나선형 열교환기 HX-H1은 수온이 $35{\sim}36^{\circ}C$범위로서 더 이상의 온도상승이 없었고, HX-H2는 수온이 $40{\sim}45^{\circ}C$로서 실험기간 중 일정한 온도분포를 보였다. 한편 HX-H3는 최고온도 $68{\sim}70^{\circ}C$, 최저온도 $30^{\circ}C$, 평균온도 $50^{\circ}C$였고, 출구의 온수온도는 $33{\sim}44^{\circ}C$ 범위로서 45일간 공급 가능하였다. 평판형 열교환기 HX-P는 수온이 $42{\sim}58^{\circ}C$로서 3개월 이상 온수공급이 가능하였으므로 4~5인 기준의 가정용 난방 및 온수공급에 문제가 없는 것으로 확인되었다. 그러므로 평판형 열교환기 HX-P는 나선형 열교환기 HX-H에 비해 발효상 내부에 열교환용 파이프가 빈틈없이 배치되어 발효상 전면적을 통해 발효열을 최대로 회수할 수 있었으며, $42{\sim}58^{\circ}C$의 발효열을 최대 3개월정도 이용 가능하였고, 장시간 운용에도 온도가 급강하 하는 등의 문제가 발생되지 않았다. 따라서 발효열교환기는 나선형 시스템보다는 발효열의 회수 효율이 매우 높으면서도, 열교환장치의 제작, 설치, 해체가 용이한 평판형 시스템이 유리한 것으로 나타났다.

• Environmental Engineering Research
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• 제23권1호
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• pp.92-98
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• 2018

Suitability of aluminium-based water treatment sludge (WTS), a waste product from water treatment facilities, was assessed for removal of heavy metals from an electroplating wastewater which had high concentrations of copper and chromium along with other heavy metals. Batch tests with simulated wastewater in single- and multi-metal solutions indicated the influence of initial pH and WTS dose on removal of six metals namely Cu(II), Co(II), Cr(VI), Hg(II), Pb(II) and Zn(II). In general, removal of cationic metals such as Pb(II), Cu(II) and Zn(II) increased with increase in pH while that of anionic Cr(VI) showed a reduction with increased pH values. Tests with multi-metal solution showed that the influence of competition was more pronounced at lower WTS dosages. Column test with diluted (100 times) real electroplating wastewater showed complete removal of copper up to 100 bed volumes while chromium removal ranged between 78-92%. Other metals which were present in lower concentrations were also effectively removed. Mass balance for copper and chromium showed that the WTS media had Cu(II) and Cr(VI) sorption capacities of about 1.7 and 3.5 mg/g of dried sludge, respectively. The study thus indicates that WTS has the potential to be used as a filtration/adsorption medium for removal of metals from metal-bearing wastewaters.

• 한국대기환경학회지
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• 제20권5호
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• pp.663-670
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• 2004

The catalytic oxidation of benzene, toluene and xylene over a spent industrial catalyst (Pd-based) was investigated in a fixed bed flow reactor system. According to the priming condition, the properties of a spent Pd-based catalyst were characterized by XRD(X-ray diffraction). BET(Brunauer-Emmett-Teller) and ICP(Inductively coupled plasma). When air was used as a primer, optimum priming temperature was found to be 200$^{\circ}C$, and the catalytic activity decreased as the priming temperature increased. When a spent Pd-based catalyst primed with air at 200$^{\circ}C$ was re-treated with hydrogen at 200$^{\circ}C$, 300$^{\circ}C$ or 400$^{\circ}C$, respectively, the catalytic activity increased and thermal effect were negligible. $HNO_3$ aqueous solution priming resulted in slight decrease of the catalytic activity, with little effects on $HNO_3$ concentrations. The activity of a spent Pd-based catalyst with respect to VOC molecule was observed to follow sequence: xylene> toluene> benzene. Benzene. toluene and xylene could be removed to almost 100% by a spent Pd-based catalyst primed with hydrogen.

• 한국환경보건학회:학술대회논문집
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• 한국환경보건학회 2005년도 국제학술대회
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• pp.365-370
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• 2005

The objective of this study is to develop the sorbent of oyster shell, which can remove gaseous acid pollutants emitted from the incinerator and power plants. The physicochemical properties of prepared absorbents have been measured using ICP and BET Also, this study is to investigate the Hydration/calcination reaction in the fixed bed reactor. Thus, the results could be summarized as follows. Oyster shell can be used in powder type without former processing. It should be also noted that sulfation reactivity of oyster sample increases to about 5 times by calcination/hydration reaction due to the increase of specific surface area and pore volume. From these experiments, we have found that both $SO_2$ and $NO_x$ in simulated flue gas can be effectively removed by use of oyster absorbent.

• Ocean and Polar Research
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• 제29권3호
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• pp.217-231
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• 2007

To explore limiting factors of spring bloom caused by waste disposal after dumping activity commenced in the Yellow Sea, we used a 1-dimensional temperature-ecological coupled model. The vertical structure of temperature and vertical diffusivity (Kh) are calculated by the temperature model with sea surface temperature using the 2.5 layers turbulence closure scheme. The ecological model applied results at the temperature model consisted of five state variables (DIN, DIP, phytoplankton, zooplankton, and detritus) forced by photosynthetically available radiation. We simulate year-to-year variations of plankton and nutrients using the coupled model from 1998 to 2000 and compare results of the model with observed data. It turned out that temperature is the growth factor of spring bloom in dumping area. During the winter the weak stratification made sufficient supply of the accumulated nutrients from the sea bed into the upper water column and led to the bloom in the coming spring. Radiation also turned out to be another important factor of spring bloom in the study area. Insufficient radiation of March 1999 showed low chlorophyll-a concentration despite sufficient nutrients in the surface.

• Journal of Microbiology and Biotechnology
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• 제15권5호
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• pp.977-983
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• 2005

The removal characteristics of ethyl acetate and 2-butanol were investigated in a bench-scale down-flow biofilter packed with Jeju scoria medium. Various inlet concentrations and gas flow rates were tested. The adaptation times of microorganisms to the change of the influent concentration of ethyl acetate and 2-butanol gas were found to be about 3 days. At the inlet concentration of 300 ppmv and empty bed contact time (EBCT) of 15 see, the removal efficiencies of the biofilter for ethyl acetate and 2-butanol were above $99.9\%$. The maximum removal capacity of the biofilter for ethyl acetate was $316-318\;g/m^3/h$ and that for 2-butanol was $245-251\;g/m^3/h$. Overall, the removal capacity of the biofilter for ethyl acetate was $50-70\;g/m^3/h$ larger than that for 2-butanol. During the operation of 65 days, the pressure drop through the biofilter column was maintained below $13\;mmH_{2}O/m$. Although the pH in the drain water decreased from 7.2 to 5.0, the pH drop did not affect the removal of the gases. From the above results, the biofilter using Jeju scoria as a packing material seemed to very effectively treat waste gases such as ethyl acetate and 2-butanol.

• Environmental Engineering Research
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• 제25권1호
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• pp.80-87
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• 2020

Landfill waste decomposition generates a dark effluent named, leachate which is characterized by high organic matter content. To minimize these polluting effects, it becomes necessary to develop an effective landfill leachate treatment process. The objective of this study was to evaluate the performance of an innovative approach based on air stripping, anaerobic digestion (AD) and aerobic activated sludge treatment. A reduction of 80% of ammonia and an increase of carbon to nitrogen ratio to 25 were obtained, which is a suitable ratio for AD. This latter AD was performed in fixed bed reactor with progressive loading rate that reached 2 and 3.2 g COD/L/d for the raw and diluted leachate (1:2), respectively. The anaerobic treatment led to significant removal of chemical oxygen demand (COD) and biogas production, especially for the diluted leachate. The COD removal was of 78% for the raw leachate and a biogas production of 4 L/d with 70% methane content. The use of the diluted leachate led to 81% of COD removal and 7 L/d biogas with 75% methane content. It allowed a removal of 77% COD and more than 97% of the organic compounds present in the initial leachate sample.

• 한국연소학회:학술대회논문집
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• 대한연소학회 2003년도 제27회 KOSCO SYMPOSIUM 논문집
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• pp.243-250
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• 2003

The present study discuss about numerical methods to analyze design parameters of pyrolysis-melting incineration system. Various numerical methods of different viewpoint are introduced to simulate the performance of the system. Process analysis of the overall system is the beginning procedure of basic design process. Heat and material flow of each element are connected and are influential to each other, hence, an appropriate process modeling should be executed to prevent from unacceptable process design concepts that may results in system failure. Models to simulate performance of each elementary facility generate valuable informations on design and operation parameters, and, derive the basic design concept to be optimized. A pyrolysis model derived from waste bed combustion model is introduced to simulate the mass conversion and heat transfer in the pyrolysis process. CFD(Computational fluid dynamics) is an effective method to optimize the thermal reacting flow in various reactors such as combustor and heat exchanger. Secondary air jets arrangement and the shape of the combustor could be optimized by CFD technology.