• 한국세라믹학회지
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• 제51권5호
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• pp.386-391
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• 2014

Silicon nitride ($Si_3N_4$) is regarded as one of the most promising materials for high temperature structural applications due to its excellent mechanical properties at both room and elevated temperatures. However, one high-temperature $Si_3N_4$ material intended for use in radomes has a relatively high dielectric constant of 7.9 - 8.2 at 8 - 10 GHz. In order to reduce the dielectric constant of the $Si_3N_4$, an in-situ reaction process was used to fabricate $Si_3N_4-SiO_2$-BN composites. In the present study, an in-situ reaction between $B_2O_3$ and $Si_3N_4$, with or without addition of BN in the starting powder mixture, was used to form the composite. The in-situ reaction process resulted in the uniform distribution of the constituents making up the composite ceramic, and resulted in good flexural strength and dielectric constant. The composite was produced by pressure-less sintering and hot-pressing at $1650^{\circ}C$ in a nitrogen atmosphere. Microstructure, flexural strength, and dielectric properties of the composites were evaluated with respect to their compositions and sintering processes. The highest flexural strength (193 MPa) and lowest dielectric constant (5.4) was obtained for the hot-pressed composites. The strength of these $Si_3N_4-SiO_2$-BN composites decreased with increasing BN content.

• 센서학회지
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• 제26권6호
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• pp.438-444
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• 2017

In this paper, we focus on optimization of the in-situ phosphorous (P) doping of low-pressure chemical vapor deposited (LPCVD) poly Si resistors for obtaining near-zero temperature coefficient of resistance (TCR) at temperature range from 25 to $600^{\circ}C$. The deposited poly Si films were annealed by rapid thermal anneal (RTA) process at the temperature range from 900 to $1000^{\circ}C$ for 90s in nitrogen ambient to relieve intrinsic stress and decrease the TCR in the poly Si layer and get the Ohmic contact. After the RTA process, a roughness of the thin film was slightly changed but the grain size and crystallinity of the thin film with the increase in anneal temperature. The film annealed at $1,000^{\circ}C$ showed the behavior of Schottky contact and had dislocations in the films. Ohmic contact and TCR of $334.4{\pm}8.2$ (ppm/K) within 4 inch wafer were obtained in the measuring temperature range of 25 to $600^{\circ}C$ for the optimized 200 nm thick-poly Si film with width/length of $20{\mu}m/1,800{\mu}m$. This shows the potential of in-situ P doped LPCVD poly Si as a resistor for pressure sensor in harsh environment applications.

• Korean Chemical Engineering Research
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• 제47권3호
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• pp.287-291
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• 2009

전도된 정체점 흐름을 갖는 반응기 안의 가열된 석영(quartz) 표면에서 암모니아($NH_3$)가 분해되는 반응을 실험과 수치 모사을 이용하여 조사하였다. 질소($N_2$)와 혼합된 8 mole%의 암모니아를 사용하였고 반응 표면으로 사용된 석영 표면을 가열하기 위한 전열기의 온도는 $300{\sim}900^{\circ}C$ 범위로 설정하였다. 라만 분광법(in situ Raman spectroscopy)을 이용하여 획득한 반응기 내부의 온도와 암모니아 농도 정보를 반응기 모델을 이용하여 분석한 결과, 전열기의 온도 설정에 의존하는 석영 표면의 온도는 $235{\sim}619^{\circ}C$ 범위였으며 암모니아 분해 반응의 활성화 에너지는 10.9~15.8 kcal/mol 범위를 가졌다.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2001년도 추계학술대회 논문집
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• pp.17-20
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• 2001

Nonvolatile semiconductor memory devices with reoxidized nitrided oxide(RONO) gate dielectric were fabricated, and nitrogen distribution and bonding species which contributing memory characteristics were analyzed. Also, memory characteristics of devices according to anneal temperatures were investigated. The devices were fabricated by 0.35$\mu\textrm{m}$ retrograde twin well CMOS processes. The processes could be simple by in-situ process of nitridation anneal and reoxidation. The nitrogen distribution and bonding state of gate dielectric were investigated by Dynamic Secondary Ion Mass Spectrometry(D-SIMS), Time-of-Flight Secondary ton Mass Spectrometry(ToF-SIMS), and X-ray Photoelectron Spectroscopy(XPS). Nitrogen concentrations are proportional to nitridation anneal temperatures and the more time was required to form the same reoxidized layer thickness. ToF-SIMS results show that SiON species are detected at the initial oxide interface and Si$_2$NO species near the new Si-SiO$_2$ interface that formed after reoxidation. As the anneal temperatures increased, the device showed worse retention and degradation properties. These could be said that nitrogen concentration near initial interface is limited to a certain quantity, so excess nitrogen are redistributed near the Si-SiO$_2$ interface and contributed to electron trap generation.

• 한국생물공학회:학술대회논문집
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• 한국생물공학회 2001년도 추계학술발표대회
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• pp.286-289
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• 2001

Anaerobic ammonium oxidation with nitrite to $N_2$(anammox) is a recently discovered microbial reaction with interesting potential for nitrogen removal from wastewater. Here we investigated the microbial community structure in the sequencing batch reactor(SBR) with an anammox activity. The SBR was optimized for the enrichment of a very slowly growing microbial community and showed that possibility of anaerobic ammonium oxidation. Fluorescence in situ hybridization(FISH) analysis revealed that anaerobic ammonium oxidizers were Candidatus Brocadia anammoxidans and Candidatus Kuenenia stuttgartiensis. Furthermore, Nitrosomol1as spp. of the ${\beta}$ -subclass of Proteobacteria was also present within the anaerobic SBR microorganisms.

• 한국환경과학회지
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• 제11권12호
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• pp.1333-1337
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• 2002

A significant fraction of nutrients, such as nitrogen and phosphorus released from sediment are utilized by primary production in the shallow water of coast and lake. The purpose of this study is to introduce the mechanism of nutrients release from sediment and to introduce the methods of the measurement of nutrient released from sediment. One approach is to calculate nutrients released from sediment by a concentration gradient between sediment pore waters and overlying water based on the Fick's law. The other approaches of measurement are the undisturbed sediment core experiments and measurement of nutrient released from sediment by the in situ chamber equipment.

• 한국유기농업학회지
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• 제26권2호
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• pp.281-296
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• 2018

본 연구에서는 재고미의 사료가치 평가를 위해 무처리(Control)를 비롯한 Extruding, Roasting, Steam 처리구들의 영양소 성분분석, in vitro 소화율, in situ 소화율을 분석하였다. In vitro 실험에서 Extruding은 건물 소화율과 gas 발생량이 타 처리구에 비해 상대적으로 높았고, 가장 낮은 pH를 보였으며, 특히 배양 시간 초기에 소화가 신속히 발생하였다. $NH_3-N$ 함량은 배양 6 h 이후에서 Control이 Extruding, Roasting, Steam에 비해 유의적으로 높은 값을 보였고, 이는 가열처리된 단백질의 반추위 미생물의 이용성 저하에 따른 결과로 보이나, 더 정확한 결과를 위해 건물 소화율 분석뿐 아니라 CP 소화율 분석이 필요할 것으로 사료된다. VFA 발생량에서는 Extruding이 다른 처리구들에 비해 배양 6, 12 h에서 유의적으로 높았는데 이는 Extruding 처리구의 분해가 배양 초기에 주로 이어져 발생한 결과로 추정된다. 전분을 발효시키는 박테리아에 의해 높은 비율로 생산되는 propionate 증가 폭에서도 같은 경향을 보였다. In situ 소화율은 in vitro의 소화율과는 다소 차이가 있는 것으로 여겨지나, 이는 실험 방법에 대한 오차로 여겨질 수 있으며, ED(유효분해율)를 통해 in vitro 시험과 소화율의 경향성이 유사한 것을 알 수 있었다. 따라서 본 연구결과를 근거로 상대적으로 적합한 사료가공 처리방법은 무처리, Roasting 및 Steaming인 것으로 보여진다. 또한 무처리(control)의 경우 가공처리에 따른 추가비용 발생이 없으므로 경제적으로 유리할 것으로 판단된다. 재고미가 TMR의 원료로 이용될 수 있다면 국내에서 자급 가능한 사료원료로써 우수한 경제성을 지닐 수 있을 것이다.

• 한국물환경학회지
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• 제22권4호
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• pp.599-604
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• 2006

Nitrogen removal with the combined SHARON (Single reactor system for high ammonium removal over nitrite)ANAMMOX (Anaerobic ammonium oxidation) process using the effluent of ADEPT (Anaerobic digestion elutriated phased treatment) slurry reactor with very low C/N ratio for piggery waste treatment was investigated. For the preceding SHARON reactor, ammonium nitrogen loading and removal rate were $0.97kg\;NH_4-N/m^3_{reactor}/day$ and $0.68kg\;NH_4-N/m^3_{reactor}/day$ respectively. In steady state, bicarbonate alkalinity consumption for ammonium nitrogen converted to $NO_2-N$ or $NO_3-N$ was 8.4 gram per gram ammonium nitrogen. The successive ANAMMOX reactor was fed with the effluent from SHARON reactor. The loading and removal rate of the soluble nitrogen defined as the sum total of $NH_4-N$, $NO_2-N$ and $NO_3-N$ in ANAMMOX reactor were $1.36kg\;soluble\;N/m^3_{reactor}/day$ and $0.7kg\;soluble\;N/m^3_{reactor}/day$, respectively. The average $NO_2-N/NH_4-N$ removal ratio by ANAMMOX was 2.41. Fluorescence in situ hybridization (FISH) analysis verified that Candidatus Kuenenia stuttgartiensis were dominate, which means that they played an important role of nitrogen removal in ANAMMOX reactor.

• Journal of Animal Science and Technology
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• 제48권4호
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• pp.541-554
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• 2006

제 3위 소화액 채취기법은 기존 반추위 영양생리 대사 패턴 측정방법인 in vivo, in vitro 및 in situ 방법의 단점을 극복하고 정확한 반추위 생리대사 패턴의 측정을 할 수 있는 기회를 가진다. 이 제 3위 소화액 채취기법을 이용한 측정방법은 기존의 post-ruminal sampling 기법과 비교해서 다음과 같은 장점들이 존재한다. 1) 단지 반추위캐뉼라가 설치된 동물만이 필요하며, 2) 제 3위 소화액에는 비교적 적은 내인성 질소가 존재하며, 3) 제 3위 소화액은 제 4위에서 시작되는 소화효소에 의한 소화를 피할 수 있는 점 등이다. 제 3위 소화액 내 반추위 미분해 용해성 질소화합물(SNAN)의 측정은 in situ 방법의 전제조건인 반추위에서 rapidly degradable N은 무한정 분해되며 따라서 비용해성 사료 N 만이 반추위를 벗어난다는 것이 오류임을 보여준다. 제 3위 소화액 내 SNAN 중 유리아미노산 및 용해성 단백질과 비교해서 양적으로 가장 많은 peptide는 반추위 단백질대사에서 peptide에서 아미노산으로의 분해과정이 분해율 제한요인이 될 수 있음을 시사한다.

• Asian-Australasian Journal of Animal Sciences
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• 제9권2호
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• pp.223-229
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• 1996

This experiment was conducted to investigate the protein sparing effect of rumen protected lysine(RPLys) and methionine hydroxyl analogue(MHA) in sheep. The treatments were $T_1$ (CP 15% + RPLys 0%), $T_2$ (CP 12% + RPLys 0%), $T_3$ (CP 12% + RPLys 0.4%) and $T_4$ (CP 12% + RPLys 0.4% + MHA 0.3%). Ruminal characteristics, in situ and in vitro digestibility and nitrogen retention rate were measured in sheep receiving different combinations of dietary supplement. The results are summarized as follows: 1. Ruminal pH and VFA concentrations were not affected by the treatments. Ruminal ammonia-N concentration was high in sheep fed diets $T_2$, $T_3$ and $T_4$ with the highest value in the $T_4$ treatment(p<0.05). 2. The digestibilities of dry matter and organic matter were not affected by the treatments. 3. Nitrogen losses through feces and urine were the highest with $T_1$ (p<0.05) and nitrogen retention rates of groups $T_1$, $T_2$, $T_3$ and $T_4$ were 18.6, 32.4, 35.5 and 27.5% of nitrogen intake, respectively, indicating that RPLys supplementation improved nitrogen retention in sheep.