• 한국수산과학회지
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• 제33권1호
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• pp.70-74
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• 2000

우뭇가사리로부터 조한천을 조제하고, 이를 실제 산업에 적용할 목적으로 $0.4\;{\mu}m$ 기공을 가지는 여과 막을 microfiltration한 후, $50{\circ}C$의 온수로써 가용성 물질을 제거하고, 0.25 N NaOH로 $70{\circ}C$에서 2시간 처리하는 알칼리 처리를 거쳐 미생물 배지용 한천을 조제하였다. 이화학적 특성을 측정한 결과에 의하면, 겔강도는 $460g/cm^2$에서$738g/cm^2$으로 상승하였고, 점도는 12 cp에서 5.2 cp로, 황산기 함량은 $1.8{\%}$에서 $0.4{\%}$로, 그리고 이수율은 $10.3{\%}$에서 $5.4{\%}$로 저하하여 제품의 품질이 월등히 향상되었다. 상용되는 미생물 배지용 한천은 겔강도가 $358{\~}368g/cm^2$, 점도는 8 cp, 황산기 함량은 $2.18{\~}2.39{\%}$ 및 시너레시스율은 $11.3{\~}12.4{\%}$로 분석되어 본 실험법으로 정제한 한천이 물성 및 성분에 있어서 휠씬 우수 하였다.

• 한국통신학회논문지
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• 제41권11호
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• pp.1630-1638
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• 2016

본 논문에서는 다중 사용자(multiuser)가 다수의 기지국 안테나(MIMO, Multiple-Input and Multiple-Output)를 동시에 사용하는 다중 사용자 massive MIMO 시스템 환경을 고려한다. 다중 사용자를 동시에 지원하기 위해 기지국에서는 ZFBF(Zero-Forcing Beamforming) 기법을 고려하고 수신 신호 검출을 위해 파일럿 신호를 고려한 하향 링크 프레임 구조를 적용하여 평균 셀 용량을 도출한다. 평균 셀 용량은 기지국 안테나 수 및 사용자 수에 대해 오목 함수 (concave function)임을 수식적으로 증명하고, 오목 함수 특징을 통해 최적의 기지국 안테나 수 및 사용자 수를 도출한다. 실험 결과를 통해 수식적으로 도출한 최적 값을 검증하고, 최적값 기반의 평균 셀 용량은 송신 SNR(Signal to Noise Ratio)에 비례하여 증가함을 확인할 수 있다.

• 대한환경공학회지
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• 제27권4호
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• pp.438-444
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• 2005

본 연구에서는 가변형 간벽을 설치하고 이 가변형 간벽의 열고 닫음에 따라 하나의 SBR 반응조를 시간적으로 뿐만 아니라 공간적으로도 분리시킴으로써 aerobic, anaerobic 또는 anoxic 상태의 구분을 명확히 하여 탈질 및 탈인 효율을 증대시켰다. 본 연구 결과 $COD_{Cr}$/N ratio 10($BOD_5$/N ratio 5) 정도의 실 플랜트 조건에서 T-N 및 T-P 제거효율은 90.9%와 75%를 나타내었다. 또한 잉여슬러지내 인 함유량 조사결과 기존 처리장에서 발생된 잉여슬러지의 인 함량비율을 100%라 할 때 pilot plant에서 발생된 잉여슬러지의 인 함유율은 생 슬러지의 경우 133.6%, 건조 슬러지의 경우 124.3%로서 기존 처리장의 슬러지내 인 함유율보다 $25{\sim}30%$ 정도 높은 것으로 조사되었다. 따라서 SBR반응조 내에 가변형 간벽을 설치함으로서 명확한 탈질 탈인을 위한 반응조건을 제시해 줄 수 있는 것으로 나타났다.

• 상하수도학회지
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• 제25권3호
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• pp.383-390
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• 2011

In this study, a process combined biofiltration with sulfur-utilizing autotrophic denitrification and membrane separation was proposed to examine the efficiency of nitrogen removal. As an experimental device, hollow-fiber module was installed in the center of reactor to generate the flux forward sulfur layer in the cylinder packed with granular sulfur. In addition, a simple module was installed in activated sludge aeration tank which inside and outside of sulfur-using denitrification module was covered with microfilter and the module was considered as an alternative of clarifier. The experiment for developing new MBR process was carried out for three years totally. As the results of first two-year experiment, successful nitrogen removal performance was revealed with lab-scale test and pliot scale plant using artificial wastewater and actual plating wastewater. In this year, pilot scale test using actual domestic wastewater was performed to prove field applicability. As the results, high-rate nitrogen removal performance was confirmed with about 0.19 kg ${NO_3}^--N/m^3$ day of rate. Also significant fouling and pressure increase were not found during the experiment. And, the production ratio of sulfate and the consumption ratio of alkalinity showed a slightly higher value about 311 mg ${SO_4}^{2-}/L$ and 369 mg $CaCO_3$/L, respectively. In conclusion, the developed MBR process can be utilized as an alternative for retrofiting existing wastewater plants as well as new construction of advanced sewage wastewater treatment plants, with cost-effective merit.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2008년도 추계 학술발표회
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• pp.1463-1474
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• 2008

In order to investigate stabilization effect and sustainability on As-contaminated farmland soils which were affected the abandoned mine site and stabilized by zerovalent iron(ZVI) and industrial by-products, batch-scale and pilot-scale tests were carried out. In batch tests, ZVI and industrial by-products(blast furnace slag, steel refining slag and oyster shell powder) were used in treatment materials to reduce the As leaching. Industrial by-products were mixed with As-contaminated soils, in the ratio of 1%, 3%, 5% and 7% on the weight base of dried soil. The results of batch-scale tests was shown that the reduction of As concentration was observed in all samples and it was expected that ZVI and steel refining slag were more effective than other treatment materials to stabilize As compounds. In pilot-scale tests, columns were filled with untreated soils and treated soils mixed with ZVI and steel refining slag in the same mixing ratio of 3%. Distilled water was discharged into the columns with the velocity of 0.3 pore volume/day. During the test, pH, EC, Eh and As concentration were measured in the regular term(1pore volume). after six months, pilot-scale tests were retested to investigate sustainability of treatment materials. As a result, It was shown that the leachate from control column was continuously released during the test period and its concentration was greater than $100ug{\cdot}L^{-1}$ which was exceeded the national regulation of water discharged to river or stream ($50ug{\cdot}L^{-1}$). On the other hand, soil treated with ZVI and steel refining slag showed that the concentrations of leachate were lower than national regulation of water discharged to river or stream. Therefore it was expected that ZVI and steel refining slag could be applied to the farmland site as the alternative treatment materials.

• 한국통신학회논문지
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• 제25권8A호
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• pp.1223-1230
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• 2000

본 논문에서는 수신된 신호의 세기를 기준으로 핸드오프를 수행하는 기존의 방식에서 야기되는 단점 통화품질의 저하 시스템의 용량감소 불필요한 전력소모등 -을 보완하고 보다 효율적으로 핸드오프를 수행하기 위해 파일럿 채널의 신호 대 간섭비 즉 칩 에너지 대 간섭 전력비를 기준으로 핸드오프 수행여부를 결정하는 방식을 제안하였다 또한 통화가 이루어질 수 있는 최소 임계치 사용중인 통화 채널의 수와 전체 통화 채널 수의비로 나타나는 셀로딩 그리고 DS-CDMA 시스템의 순방향 링크 네 개 채널 중 파일럿 채널에 할당된 절력 비등을 변화시켰을 때 히스테리시스 레벨에 따라 이동체가 한 기지국에서 다른 기지국으로 이동하는 동안 발생하는 평균핸드오프수를 분석하였다.

• 한국연소학회:학술대회논문집
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• 한국연소학회 2005년도 제31회 KOSCO SYMPOSIUM 논문집
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• pp.238-244
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• 2005

This study performs the pilot-plant experiments to evaluate the effect of the oxygen enrichment on the co-incineration of municipal solid waste and organic sludge from a wastewater treatment facility. The design capacity of the stoker-type incinerator pilot-plant is 150 kg/h. Combustion chamber temperatures were measured as well as the stack gas concentrations, i.e., NOx, CO, and the residual oxygen. The maximum ratio of organic sludge waste to the total waste input is 30%. Also the oxygen-enriched air with 23% of oxygen in supplied air is used for stable combustion. As the co-incineration ratio of the sludge increased up to 30% of the total waste input, the primary and the secondary combustion chamber temperature was decreased $to900^{\circ}C$ (primary combustion chamber), $750^{\circ}C$(secondary combustion chamber), respectively, approximately $200^{\circ}C$ below the incineration temperature of the domestic waste only (primary: $1,100^{\circ}C$, secondary: $950^{\circ}C$). However, if the supplied air was enriched to 22% oxygen content in air, the incinerator temperature was high enough to burn the waste mixture with 30% sludge, which has the heating value of 1,600 kcal/kg.

• 한국연소학회:학술대회논문집
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• 한국연소학회 2004년도 제28회 KOSCO SYMPOSIUM 논문집
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• pp.42-48
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• 2004

Lean laminar premixed propane and methane flames which were anchored by a hydrogen-pilot flame in a tube were investigated experimentally. The flame shapes were observed by varying mean velocity from 10cm/s to 140cm/s and equivalence ratio from 0.45 to 0.8. In this study, behaviors of flames are divided into five regions such as tail-out, flash-back, flickering, stable and vibrating flames with respect to the mean velocity and the equivalence ratio. Although the flames are unstable in both the flickering and the vibrating region, they have different characteristics such as the frequency, sound generation and creation process of flame curvature. The flickering region exists near the flammability limit and the flame flickers in a frequency of about 10Hz. When flame front is bended, the propane flame front is straightened and the methane flame front is bended more by thermo-diffusive instability. In the vibrating region, the flame vibrates emitting audible sound in a frequency of about 100Hz. In the boundary of vibrating region, the vibration of flame changes between two modes such as single frequency vibration and dual frequency vibration. Increase and decrease of vibration in each mode are determined by thermo-acoustic instability.

• 한국환경복원기술학회지
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• 제5권6호
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• pp.9-13
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• 2002

This study has been performed to investigate the physical and mechanical characteristics of compaction, volume change and compressive strength for reinforced soil mixed with cement. And confirm the reinforcing effects with admixture such as cement. To this end, a series of compaction test and compression test was conducted for clayey soil(CL) and cement reinforced soil. In order to determine proper moisture content and mixing ratio, pilot test was carried out for soil and cement reinforced soil. And the mixing ratio of cement admixture was fixed 3%, 6%, 9% and 12% by the weight of dry soil. As the experimental results, the maximum dry unit weight(${\gamma}_{dmax}$) was increased with the mixing ratio and then shown the peak at 10% reinforced soil, but the optimum moisture content(OMC) and the volume change was decreased with the ratio increase. And the compressive strength volume change was decreased with mixing ratio increased.

• 한국지하수토양환경학회:학술대회논문집
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• 한국지하수토양환경학회 2004년도 총회 및 춘계학술발표회
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• pp.205-208
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• 2004

Tile pilot scale biopile system was designed and constructed for evaluation of biopile efficiency. For the biopile system construction, two soil samples that were contaminated by mainly diesel were selected. The pilot scale biopile were consisted of the biopile dome, aeration system and monitoring system and two biopiles(pile A and pile B) were operated with nutrients and inoculum for more 100 days. The initial TPH concentrations for pile A and pile B were about 10,000 mg/kg and 2,300 mg/kg, respectively. After 70 days, the microbial densities in the pile A was increased and in the pile B it was no changed. The TPH contents decreased about 70% in the pile A and 30% in the pile B. Also, various kinds of PAHs were detected by analyzing the GC/MSD, and the reducing ratio in the piles A and pile B were similarly declined. The average biodegradation rates were calculated about 66.8mg/kg-day in the pile A and 10.9mg/kg-day in the pile B. During the operation period, pile temperature was the major limiting condition for the efficiency of all biopiles.