• 한국세라믹학회지
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• 제41권9호
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• pp.703-708
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• 2004

앞선 논문 분말의 제조에서 정립한 $\alpha$-Si$_3$N$_4$ 분말의 제조를 위한 최적의 조성에서 반응 혼합물의 양에 따른 압력 및 생성물의 변화를 관찰하였다. 5L 반응기 내에서 반응 혼합물의 양이 100g일 때 필요한 최저 $N_2$ 압력은 60atm이었다. 그러나 반응 혼합물의 양이 200g 이상일 때부터 반응기 내부의 압력 증가로 인해 반응은 완료될 수 없었으며, 혼합물이 증가할수록 반응율은 직선적으로 감소하였다. 반응물의 양이 증가할수록 최초 반응기 내부의 $N_2$압력을 감소시킴으로써 반응을 완료시킬 수 있었으며, 500g일 때 초기 $N_2$ 압력을 약 20atm까지 감소시킴으로써 반응은 완료될 수 있었다. 반응이 중간에 멈추는 원인은 반응기 내부의 압력 증가로 인해 기화되지 못한 채 혼합물 안에 존재한 NH$_4$Cl때문인 것으로 밝혀졌다.

• 한국에너지공학회:학술대회논문집
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• 한국에너지공학회 2002년도 춘계 학술발표회 논문집
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• pp.227-234
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• 2002

With the increasing environmental consideration and stricter regulations, gasification of waste is considered to be more attractive technology than conventional incineration for energy recovery as well as material recycling. The experiment for combustible waste mixed with plastic and cellulosic materials was performed in the fixed bed gasifier to investigate the gasification behavior with the operating conditions. Waste pelletized with a diameter of 2~3cm and 5cm of length was gasified at the temperature range of 1100~145$0^{\circ}C$. It was shown that the composition of H$_2$ was in the range of 30~40% and CO 15~30% depending upon oxygen/waste ratio. Casification of waste due to thermoplastic property from mixed plastic melting and thermal cracking shows a prominent difference from that of coal or coke. It was desirable to maintain the top temperature up to foot to ensure the mass transfer and uniform reaction through the packed bed. As the bed height was increased, the formation of H$_2$ and CO was increased whilst $CO_2$ decreased by the char-$CO_2$ reaction and plastic cracking. From the experimental results, the cold gas efficiency was around 61% and heating values of product gases were in the range of 2800~3200㎉/Nm3.

• 터널과지하공간
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• 제7권2호
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• pp.100-107
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• 1997

In case of a fire outbreak in a uni-directional road tunnel, the flow of traffic immediately behind the fire disaster will be stalled all the way back to the entrance of the tunnel. Furthermore, when the vehicle passengers try to flee away from the fire toward the entrance of the tunnel, the extremely hot fume that propagates in the same direction will be fatal to the multitudes evacuating, but may also cause damage to the ventilation equipments and the vehicles, compounding the evacuation process. This paper will present the 3-dimensional modelling analysis of the preventive measures of such a fume propagation in the same direction as the evacuating passengers. For the analysis, the fire hazard was assumed to be a perfect combustion of methane gas injected through the 1 m X 2 m nozzle in the middle of the tunnel, and the product of $CO_2$ as the indicator of the fume propagation. From the research results, when the fire hazard occurred in middle of the 400 m road tunnel, the air density decreased around the fire point, and the maximum temperatures were 996 K and 499 K at 210 m and 350 m locations, respectively, 60 seconds after fire disaster occurred, when the fumes were driven out only towards the exit-direction of the tunnel. By tracing the increase of $CO_2$ level over 1% mole fraction, the minimum longitudinal ventilation velocity was found to be 2.40 m/sec. Furthermore, through Analysis of the temperature distribution graphs, and observation of the cross-sectional distribution of $CO_2$ over 1% mole fraction, it was found that the fume did not mix with the air, but rather moved far in a laminar flow towards exit of the tunnel.

• 환경위생공학
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• 제5권2호
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• pp.63-80
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• 1990

A sensitive and simple analytical system for the simultaneous determination of residual oxytetracycline, tetracycline, and doxycycline in honey was described, and that the analytical method for determination of residual propionic acid in honey was established. Experimental subjects were purchased four kinds of honey, native kind honey, acaccia honey, mixed floral honey, chestnut honey in Kyung Sang Nam Do. Several microbiological methods are available to determine tetracycline antibiotecs(TCs) in foods but their precision apears to be variable and the specificity is questionable. These methods are considered to be not suitable for analysis of tetracycline antibiotics in honey because honey itself has bacteriostatic action. For determination of tetracycline antibiotics in honey, therefore the High Performance Liquid Chromatography(HPLC) method was applied, and the propionic acid were determined by Gas Chromatography(5.C). Ethylacetate, as an extract solvent, was found to be suitable for seperation of TCs in honey, but methanol and acetone were not. The recoverly rate of Oxytetracycline(OTC), Tetracycline(TC), Doxycycline(DC) from honey spiked at a level of 10 $\mu $g/g were 97%, 89%, and 91%, respectively. The cailbration curve in TCs was linear expression from 2$\mu $g/ml to 10$\mu $g/ml. As the results of analysis, the residual tetracycline antibiotics were not detected in the 100 samples of honey. The recovery rate of propionic acid from honey spiked at level of 10$\mu $g/g was 98.3% , and the calibra lion curves were linear expression from 21$\mu $g/ml to 101$\mu $g/ml. As the results of analysis, the residual propionic acid was not detected in the 100 samples of honey. Retention time(min) of OTC, DC, and TC were 3.35, 4.61, and 5.30 minutes at the conditions of table 2, respectively, and retention time(min) of propionic acid was 3.50 minutes at the conditions of table 3. The residual TCs and propionic acid were not detected in the 100 samples of honey, but there is a possibility that antibiotics or propionic acid will be to remain in honey if they are used during product period in order to prevent putrefaction of honey-bee.

• 한국토양환경학회지
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• 제4권3호
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• pp.3-15
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• 1999

기존의 SVE 공정에 공기 대신 오존을 주입하여 유류물질의 지중분해를 유도하고 추출가스의 처리부담을 최소화할 수 있는 복원 신공정 개발을 위한 기초연구를 수행하였다. 이를 위하여 비휘발성 유류물질인 디젤유를 처리대상물질로 하여 토양칼럼실험을 통해 오존주입에 의한 지중분해 가능성을 검토하였다. 수분함량 8.39%의 실토양에 디젤유를 혼합하여(초기농도 1,485mg-DRO/kg-soil)칼럼에 충진시킨 후 119.0$\pm$6.1mg/L의 농도를 가지는 오존가스를 50mL/min의 유량으로 연속 주입하였을 때 14시간 반응후 칼럼 상 하부의 디젤유 제거율은 각각 87.9%, 100.0%를 나타내어 비교적 빠른 시간내에 효과적으로 처리되는 것으로 나타났다. 한편 동일한 조건에서 오존가스 대신 공기를 주입하였을 때 공기 유입 및 유출부 모두 총 14시간 동안의 접촉시간 동안 30%이내의 제거율을 나타냄에 따라 디젤오염토양에 대한 기존 SVE공정의 적용한계를 확인하였다.

• 대한기계학회논문집B
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• 제35권5호
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• pp.539-545
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• 2011

맥동연소기술을 적용한 산업용 복사관버너의 연소특성을 살펴보기 위해 실규모 (120,000 kcal/h) 산업용 복사관버너 설비를 사용하여 실험실 및 현장 테스트를 수행하였다. 제철부생가스를 사용하는 산업용 복사관버너의 3 가지 종류를 하나의 W 형 복사관이 장착된 실험설비에서 실험하였다. W 형 복사관이 다수 사용되는 대형 설비를 이용하여 장기운영 실험을 실시하였다. 맥동연소기술을 적용한 기실험설비들을 대상으로 성능향상 및 배가스조절 측면에서 다양한 실험조건으로 테스트를 진행 하였다. 맥동연소기술의 적용가능성 평가를 위해 NOx 저감 및 효율향상을 분석하였다. 맥동연소기술의 적용결과 에너지 절감, 복사관 수명 향상 및 생산성 향상 등이 얻어짐을 확인할 수 있었다. 최고의 성능 및 배가스 조절을 얻기 위한 최적의 운전조건이 각 버너별로 결정되었다.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2011년도 춘계학술대회 초록집
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• pp.99-99
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• 2011

Fuel cell systems are a completely different form of electricity source that has been used so far and is an aggregation of multiple technologies with multidisciplinary features that can be operated safely only when gas and electrical safety are being considered. Since fuel cells generate through electrochemical reactions there are difficulties in ensuring electricity safety, power quality assessment, effective control and reliability standards for system faults using conventional inspection techniques and even though they are necessary as a primary means for reduction of CO2 owing to the Climate Convention, electrical safety assessment and measures are required for the prevention of faults in residential facilities. Although small-scaled distributed power supplies can be utilized as important means of peak control and energy management measures, research is required for observing the effects on the system and the development of inspection technology to ensure stable operation, and the electrical safety of residential fuel cell systems need to be assessed and the problems derived for establishing electrical safety standards. From the year 2002, Japan has established laws on technical safety standards and development and rules on the product specifications and standards for the industrialization of hydrogen fuel cells. Also, a lot of effort have been made for the commercialization of fuel cells by building one-stop certification services. Internationally, the IEC TC 105 has established international standards based on fuel cells. In order to protect the national interest, the country should be able to respond accordingly meet global standards. In fact, in Korea, to comply with the international trend, Korea Energy Management Corporation is establishing a certified agenda for fuel cells and Korean Agency for Technology and Standards is enacting technical standards for fuel cells. The current terms of fuel cells are that research has been focused more on the quality and performance of manufactured products rather than stable power operation and maintenance over time. In this paper, by considering the household fuel cell as a power device, the safety standards of the fuel cell system for a reliable operation with the existing power system is being proposed.

• Journal of Pharmaceutical Investigation
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• 제41권6호
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• pp.331-336
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• 2011

The instability of hirsutenone (HST), a potential therapeutic candidate for the treatment of atopic dermatitis (AD) and ovarian carcinoma, is one of the main concerns for the development of drug product. In the present study, aqueous stability of HST was investigated by kinetic analysis, and the effect of several factors covering temperature, nitrogen gas ($N_2$) flushing, and selection of proper antioxidant was compared. Cosolvent system composed of distilled water and methanol (9:1 v/v) was used as a vehicle to dissolve HST at the concentration of $200{\mu}g/mL$. Samples of aqueous solution were prepared under the absence or presence of antioxidants, such as ascorbic acid (AA), sodium edetate (EDTA), and ascorbyl palmitate (AP), and subjected for stability test. The degradation of HST in aqueous solution was followed by the first order kinetics with an extremely short half life of less than a week at room temperature, and was accelerated as the temperature increased. $N_2$ flushing brought a little enhancement in stability compared to control solution, but the effect was insufficient. The addition of AA and EDTA (0.1%) significantly enhanced the stability of HST at $40^{\circ}C$, but the addition of AP (0.01%) was limited due to its water insolubility and revealed no promising result. The stability of HST was increased proportionally by the amount of AA added, showing the difference in degree of stabilization as an order of magnitude. Finally, we conclude that HST was stabilized by the addition of a suitable antioxidant, suggesting AA as the most effective stabilizer.

• 자원ㆍ환경경제연구
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• 제21권4호
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• pp.777-807
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• 2012

본 연구는 연산일반균형(CGE) 모형을 활용하여 한국의 자유무역협정(FTA) 확대 정책이 국내 에너지소비와 온실가스 배출량에 미치는 영향을 분석하였다. FTA가 국가경제와 산업구조에 변화를 초래한다면, 이는 국가 에너지수급체계와 온실가스 배출량에도 큰 영향을 끼칠 수 있기 때문이다. 다지역 다부문 CGE모형인 KEEI-GCGE를 통한 분석결과, 이미 발효된 한-미, 한-EU FTA와 더불어 한-중-일 FTA가 현실화되면 우리나라의 실질국내총생산은 2020년에 BaU대비 2.04% 증가하고, 에너지소비와 온실가스 배출량은 각각 3.33%와 1.53% 증가할 것으로 예측되었다. 이와 같은 결과는 향후 여러 국가들과 체결될 FTA는 우리나라의 경제뿐만 아니라 에너지소비와 온실가스 배출량에도 큰 변화를 야기할 가능성이 있음을 의미한다. 따라서 한국의 에너지/기후변화 관련 각종 중장기 계획과 정책들이 FTA로 인해 발생할 수 있는 에너지수급체계와 온실가스 배출량에 대한 영향을 체계적으로 반영해야 함을 시사하고 있다.

• Journal of Microbiology and Biotechnology
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• 제30권4호
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• pp.622-632
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• 2020

Phenylalanine ammonia-lyase (PAL) catalyzes the reversible deamination of phenylalanine to cinnamic acid and ammonia. Algae have been considered as biofactories for PAL production, however, biochemical characterization of PAL and its potency for myristicin biotransformation into MMDA (3-methoxy-4, 5-methylenedioxyamphetamine) has not been studied yet. Thus, PAL from Anabaena flos-aquae and Spirulina platensis has been purified, comparatively characterized and its affinity to transform myristicin was assessed. The specific activity of purified PAL from S. platensis (73.9 μmol/mg/min) and A. flos-aquae (30.5 μmol/mg/min) was increased by about 2.9 and 2.4 folds by gel-filtration comparing to their corresponding crude enzymes. Under denaturing-PAGE, a single proteineous band with a molecular mass of 64 kDa appeared for A. flos-aquae and S. platensis PAL. The biochemical properties of the purified PAL from both algal isolates were determined comparatively. The optimum temperature of S. platensis and A. flos-aquae PAL for forward or reverse activity was reported at 30℃, while the optimum pH for PAL enzyme isolated from A. flos-aquae was 8.9 for forward and reverse activities, and S. platensis PAL had maximum activities at pH 8.9 and 8 for forward and reverse reactions, respectively. Luckily, the purified PALs have the affinity to hydroaminate the myristicin to MMDA successfully in one step. Furthermore, a successful method for synthesis of MMDA from myristicin in two steps was also established. Gas chromatography-mass spectrometry (GC-MS) analysis was conducted to track the product formation.