• 한국결정성장학회지
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• 제30권3호
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• pp.96-102
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• 2020

본 논문에서는 6H-SiC (0001) 기판 위에 AlN 에피층을 혼합 소스 수소화물 기상 에피택시 방법에 의해 성장하였다. 시간당 5 nm의 성장률로 0.5 ㎛ 두께의 AlN 에피층을 얻었다. FE-SEM과 EDS 결과를 통해 6H-SiC (0001) 기판 위에 성장된 AlN 에피층 표면을 조사하였다. HR-XRD와 계산식을 통해 전위 밀도를 예측하였다. 1.4 × 10⁹ cm^-2의 나사 전위 밀도와 3.8 × 10⁹ cm^-2의 칼날 전위 밀도를 가지는 우수한 결정질의 AlN 에피층을 확인하였다. 혼합소스 HVP E 방법에 의해 성장된 6H-SiC 기판 위의 AlN 에피층은 전력소자 등에 응용이 가능할 것으로 판단된다.

• 한국결정성장학회지
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• 제29권3호
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• pp.83-90
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• 2019

본 논문에서는 전력 반도체 소자용 Mg-doped AlN 에피층을 혼합 소스 수소화물 기상 에피택시 방법에 의해 성장하였다. p형 재료로는 Mg을 사용하였다. 소자응용을 위한 기초 기판으로서 역할을 하기 위하여 GaN 에피층이 성장된 기판과 GaN 에피층이 성장되어 패턴이 형성된 사파이어 기판 위에 Mg-doped AlN 에피층을 선택 성장하였다. Mg-doped AlN 에피층의 표면과 결정 구조는 FE-SEM 및 HR-XRD에 의해 조사하였다. XPS 스펙트럼과 라만 스펙트럼 결과로부터 혼합소스 HVPE 방법에 의해 성장된 Mg-doped AlN 에피층은 전력소자 등에 응용이 가능할 것으로 판단된다.

• 한국결정성장학회지
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• 제31권3호
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• pp.103-111
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• 2021

고체 재료인 Si, Al 그리고 Ga을 혼합하는 혼합소스 수소화물기상 방법에 의해 육각형 Si 결정을 성장하였다. 새로 고안된 상압의 혼합소스 수소화물기상 방법에서는 1200℃의 고온에서 GaCl_n, AlCl_n 그리고 SiCl_n 가스 사이의 상호작용에 의해 핵이 형성된다. 또한 Si과 HCl 가스의 급격한 반응에 의해 높은 분압을 가진 전구 기체를 발생시키는 구조로 설계 되었다. 주사 전자 현미경(FE-SEM), 에너지 분산형 X-선 분광법(EDS), 고해상도 X-선 회절(HR-XRD) 그리고 라만 스펙트럼을 통하여 육각형 Si 결정의 특성을 확인하였으며, Si 산업 분야에서 새로운 소재로서 응용성이 기대된다.

• Animal Bioscience
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• 제36권5호
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• pp.720-730
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• 2023

Objective: This study investigated the effects of corn silage as a source of microbial inoculant containing antifungal and carboxylesterase-producing bacteria on fermentation, aerobic stability, and nutrient digestibility of fermented total mixed ration (FTMR) with different energy levels. Methods: Corn silage was used as a bacterial source by ensiling for 72 d with an inoculant mixture of Lactobacillus brevis 5M2 and L. buchneri 6M1 at a 1:1 ratio. The corn silage without or with inoculant (CON vs MIX) was mixed with the other ingredients to formulate for low and high energy diets (LOW vs HIGH) for Hanwoo steers. All diets were ensiled into 20 L mini silo (5 kg) for 40 d in quadruplicate. Results: The MIX diets had lower (p<0.05) acid detergent fiber with higher (p<0.05) in vitro digestibilities of dry matter and neutral detergent fiber compared to the CON diets. In terms of fermentation characteristics, the MIX diets had higher (p<0.05) acetate than the CON diets. The MIX diets had extended (p<0.05) lactic acid bacteria growth at 4 to 7 d of aerobic exposure and showed lower (p<0.05) yeast growth at 7 d of aerobic exposure than the CON diets. In terms of rumen fermentation, the MIX diets had higher (p<0.05) total fermentable fraction and total volatile fatty acid, with lower (p<0.05) pH than those of CON diets. The interaction (p = 0.036) between inoculant and diet level was only found in the immediately fermentable fraction, which inoculant was only effective on LOW diets. Conclusion: Application of corn silage with inoculant on FTMR presented an antifungal effect by inhibiting yeast at aerobic exposure and a carboxylesterase effect by improving nutrient digestibility. It also indicated that fermented feedstuffs could be used as microbial source for FTMR. Generally, the interaction between inoculant and diet level had less effect on this FTMR study.

• 한국해양학회지:바다
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• 제15권1호
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• pp.1-7
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• 2010

본 연구에서는 자연혼합배양(nature mixed culture)이라는 기법을 이용하여 해수관상어를 사육하는데 성공하였고 자연혼합배양수조에서 해수관상어의 자어는 정상적으로 성장하고 생존 가능하였다. 자연혼합배양수조에 출현한 플랑크톤성 미소생물은 모두 34종이었으며 그 중에는 Detonula pumila, Nitzschia sp., Fragilaria oceanica, Chaetoceros curvisetus, Stephanodiscus sp., Chaetoceros decipiens, Chaetoceros sp., Thalassiosira rotula, Eucampia zodiacus, Diploneis splendica, Nitzschia longissima, Surirella cuneata, Asterionella glacialis, Nitzschia spp., Chaetoceros debile, Thalassionema nitzschioides, Nitzschia, closterium, Skletonema costatum과 Licmophora sp와 같은 규조류가 19종, Euglena sp, Gonyaulax sp., Pyramimonas sp., Protoperidinium sp., Eutreptia, sp., Parapedinella sp., unidentified micro-flagellate, Gyrodinium sp., Scrippsiella trochoidea, Gymnodinium sanguineum, Chrysochromulina sp., Gymnodinium sp., Prorocentrum triestinum과 Micromonas sp.와 같은 편모조류가 14종 그리고 1종의 섬모충으로서 Mesodinium rubrum가 관찰되었다. 한편, 미소생물 종 중에서 편모조류의 한종인 Chrysochromulina sp.는 사육기간 동안 우점하였는데 이와 같은 결과는 배양 개시 후 10일째부터 지속적이고 안정적으로 유지 가능하였다.

• Environmental Sciences Bulletin of The Korean Environmental Sciences Society
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• 제2권2호
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• pp.99-108
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• 1998

Results obtained from this research showed that the anaerobic contact process was applicable to pear waste with COD removal efficiencies of up to $95\%$ depending on conditions, provided ammonium and phosphate salts were added as well as other nutrients, present in the commercial fertilizer, Milorganite or in yeast extract. These latter materials were required in minimum concentrations of 5 and 1.5 g/L, respectively, in the feed independent of HRT and volatile solids loading rate, with part of the effect due to the mineral fraction. Digestion was satisfactory over the whole range of volatile solids loading rates and liquid retention time of 30 to 0.5 days tested, although treatment efficiency dropped off noticeably between 1 and 0.5 day liquid retention time because of poorer flocculation and separation of anaerobic bacteria. Settling of anaerobic bacteria including methane producing bacteria was related to settling of mixed liquor suspended solids only at 1 to 5 days liquid retention times, at other liquid retention times anaerobic microorganism settled markedly less efficiently than mixed liquor suspended solids. Further studies are being made to provide information of practical and basic interest. Data on the composition of the active fraction of yeast extract might solve many practical nutrient problems encountered with the anaerobic contact process and improve its economics. Further improvement in the flocculation and settling of anaerobic bacteria as well as other bacteria would improve overall performance and allow the use of shorter liquid retention times with dilute waste. Knowledge about the numbers of methane formers present would allow a degree of understanding and control of the process not presently attainable.

• Imaging Science in Dentistry
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• 제36권1호
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• pp.63-68
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• 2006

Desmoplastic ameloblastoma is a rare histologic variant of ameloblastoma. It shows important differences in anatomic distribution, histologic appearance, and radiographic findings compared with the general type of ameloblastoma. It is histologically characterized by an abundance of densely collagenous stroma and radiographically a mixed radiolucent-radiopaque lesion. We present three cases of desmoplastic ameloblastoma. All the patients complained on buccal swelling with or without pain and the sites of occurrence were the anterior and the premolar region. Plain radiographs showed mixed radiopaque-radiolucent lesion with ill-defined or diffuse sclerotic margin and no external root resorption. Additionally, CT scans revealetl buccal expansion and relatively well-defined margin of the lesions. The clinical and radiographic features of the presented cases were compared with those of the desmoplastic ameloblastoma in the previous literatures.

• 한국대기환경학회지
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• 제24권4호
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• pp.455-469
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• 2008

VOCs (Volatile organic compounds) are known as one of the harmful chemicals, causing cancer and global warming. Therefore, the proper control, removal, and reduction of the emission of VOCs are important tasks for the environmental protection. Among the method of VOCs removal activated carbon bed is the most efficient and economical method. In this study, the adsorption performance of toluene gas was investigated using various activated carbons. To find out the adsorption efficiency, the H/D (Height/Diameter) of the activated carbon and GHSV (Gas Hourly Space Velocity) of the toluene gas were manipulated with various conditions. The effect of the temperature, humidity and toluene-MEK-IPA mixed gas on adsorption were also investigated. As a result, a high adsorption performance was found when GHSV is lower at room temperature and low humidity. It was also found that the adsorption efficiency of toluene-MEK-IPA mixed gas system was lower than that of toluene gas system.

• 한국분말재료학회지
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• 제18권3호
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• pp.262-268
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• 2011

In order to investigate the microstructure and mechanical properties of WC-10 wt% Co insert tool alloy fabricated by PIM (Powder Injection Molding) process, the feedstock of WC-10 wt% and wax used as a kind of binder were mixed together by two blade mixer. After injection molding, the debinding process was carried out by two-steps. First, solvent extraction, in which the binder was eliminated by putting the specimen into normal hexane for 24 hrs at $60^{\circ}C$, and subsequently thermal debinding which was conducted at $260^{\circ}C$ and $480^{\circ}C$ for 6 hrs in the mixed gas of $H_2/N_2$, respectively. Meantime, in order to compensate the decarburization due to hydrogen, 1.2~1.8% of carbon was added to ensure the integrity of the phase. Finally, the specimens were sintered in vacuum under different temperatures, and the relative density of 99.8% and hardness of 2100 Hv can be achieved when sintered at $1380^{\circ}C$, even the TRS is lower than the conventional sintering process.

• Elastomers and Composites
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• 제33권5호
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• pp.324-334
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• 1998

방수재로 사용하는 EVA 에멀젼 수지에 라텍스 형태의 아크릴 수지, 에폭시 수지, 우레탄 수지, SBR 수지를 $0{\sim}50%$ 혼합하여 점성, 건조특성, 경도 등을 실험하였다. 점도는 라텍스함량 20%까지는 현저하게 떨어졌고 그 이상에서는 유사한 점도를 나타내었는데 점도에 가장 영향을 미치는 것은 EVA 수지와의 상용성이었다. 가사시간은 혼합 후 $30{\sim}40분$ 이내인 것으로 나타났는데 가사시간에 가장 영향을 미치는 요인은 시멘트와의 반응성이었다. 지촉건조시간은 에폭시>SBR>우레탄>아크릴의 순서로 나타났는데 수지의 종류와 시멘트의 양에 따라 다른 특성을 나타내었다. 라텍스 혼합물의 경도는 연필경도 $4B{\sim}H$를 나타내었는데 시멘트를 충전했을 때 현저하게 높은 경도를 나타내었다.