• 유체기계공업학회:학술대회논문집
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• 유체기계공업학회 2006년 제4회 한국유체공학학술대회 논문집
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• pp.569-572
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• 2006

In present study, the influence of changing combustor pressure on flame stabilization and nitrogen oxide (NOX) emission in the swirl flame with secondary fuel injection was investigated. The combustor pressure was controlled by suction at combustor exit. Pressure index ($P^*=Pabs/Patm$), where Pabs and Patm indicated the absolute pressure and atmosphere pressure, was controlled in the range of 0.7~1.15 for each equivalence ratio conditions. It could be observed that flame stable region became narrower with decreasing equivalence ratio and pressure index. In this combustion system, stable flames were formed until $P^*=\;0.7$. Emission index decreased with decreasing pressure index for overall equivalence ratio conditions and NOx reduction rates were almost identical for $P^*<1$ regardless of equivalence ratio though EINOx values showed different level with change of equivalence ratio for $P^*{\geq}1$. It is also observed that EINOx decreased with increasing secondary fuel injection ratio. Emission index of nitric oxide was controllable by adjusting the changing combustor pressure and injecting secondary fuel and this NOx reduction technology is applicable to industrial furnaces and air conditioning system.

• 한국재료학회:학술대회논문집
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• 한국재료학회 2005년도 춘계학술발표대회 및 제8회 신소재 심포지엄 논문개요집
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• pp.302-302
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• 2005

• 한국자기학회:학술대회 개요집
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• 한국자기학회 2005년도 하계학술연구발표회 논문개요집
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• pp.122-123
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• 2005

• Current Research on Agriculture and Life Sciences
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• 제3권
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• pp.85-91
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• 1985

Fuji의 감압저장중(減壓貯藏中) 품질변화(品質變化)에 미치는 영향을 효소적(酵素的)인 면(面)에서 관찰하고자 preclimacteric 단계에서 수확하여 상온(常溫)($15^{\circ}C$) 및 저온(低溫)($2^{\circ}C$), 감압(減壓)(380mmHg) 및 상압(常壓)(760mmHg)에서 저장(貯藏)하여 경도(硬度), 산(酸), 당(糖) 그리고 효소활성(酵素活性)의 변화 및 전기영동형(電氣泳動型)의 변화를 관찰하였다. Fuji 사과의 Acid-phosphatase는 cell wall fraction에 주로 존재하며 climacteric maximum에서 최고의 활성(活性)을 보였으며 이후로 감소하는 경향이었으며 상온상압구(常溫常壓區)에서 변화의 폭이 가장 크고 활성(活性)이 높았으며 그 다음 상온감압구(常溫減壓區), 저온상압구(低溫常壓區), 저온감압구(低溫減壓區)의 순(順)이었다. 효소(酵素)의 최적(最適) pH는 5.5, 최적온도(最適溫度)는 $45^{\circ}C$였다. 열(熱)과 pH의 안정성(安定性)을 조사한 결과 $30^{\circ}C$까지는 안정하였으며 pH 5~8사이에 안정하였다. 무기감(無機監) 영향에서는 Fe, Hg에 의해서 크게 저해(沮害)되었다. 저장중 상온상압구(常溫常壓區)와 저온감압구(低溫減壓區)에서 저장기간별로 추출해낸 효소액(酵素液)을 전기영동(電氣泳動)시킨 결과 전기간(全期間)에 걸쳐서 약간의 변화를 나타내었다.

• 대기
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• 제20권4호
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• pp.399-414
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• 2010

Sand and dust storm in East Asia, so called Asian dust, is a seasonal meteorological phenomenon. Mostly in spring, dust particles blown into atmosphere in the arid area over northern China desert and Manchuria are transported to East Asia by prevailing flows. An Asian dust event occurred on 6-8 May 2007 is chosen to investigate how sensitive the Asian dust transport forecast to the initial condition uncertainties and to interpret the characteristics of sensitivity structures from the viewpoint of dynamics and predictability. To investigate the forecast sensitivities to the initial condition, adjoint sensitivities that calculate gradient of the forecast aspect (i.e., response function) with respect to the initial condition are used. The forecast aspects relevant to Asian dust transports are dry energy forecast error and lower tropospheric pressure forecast error. The results show that the sensitive regions for the dry energy forecast error and the lower tropospheric pressure forecast error are initially located in the vicinity of the trough and then propagate eastward as the surface low system moves eastward. The vertical structures of the adjoint sensitivities for the dry energy forecast error are upshear tilted structures, which are typical adjoint sensitivity structures for extratropical cyclones. Energy distribution of singular vectors also show very similar structures with the adjoint sensitivities for the dry energy forecast error. The adjoint sensitivities of the lower tropospheric pressure forecast error with respect to the relative vorticity show that the accurate forecast of the trough (or relative vorticity) location and intensity is essential to have better forecasts of the Asian dust event. Forecast error for the atmospheric circulation during the dust event is reduced 62.8% by extracting properly weighted adjoint sensitivity perturbations from the initial state. Linearity assumption holds generally well for this case. Dynamics of the Asian dust transport is closely associated with predictability of it, and the improvement in the overall forecast by the adjoint sensitivity perturbations implies that adjoint sensitivities would be beneficial in improving the forecast of Asian dust events.

• 한국약용작물학회지
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• 제20권3호
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• pp.171-176
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• 2012

This study was conducted to investigate the effect of atmosphere-leaf vapor pressure deficit (VPD) in Allium microdictyon Prokh. and Allium ochotense Prokh. The vapor pressure deficit (VPD) was rapidly increased with increasing temperature and decreasing relative humidity. Taken as a whole, the stomatal transpiration reaction was slightly late with increading of VPD. Maximum photosynthetic rate at high-VPD condition was 5.98 ${\mu}mol$ $CO_2{\cdot}m^{-2}{\cdot}s^{-1}$ in Allium microdictyon, which was a little lower than 6.59 ${\mu}mol$ $CO_2{\cdot}m^{-2}{\cdot}s^{-1}$ in Allium ochotense, respectively. After 2 p.m, stomatal transpiration of Allium microdictyon at the high VPD condition were rapidly decreased. Ci/Ca began to decline sharply at 8 a.m and showed the lowest value at 2 p.m, The results showed that Ci/Ca decreased with being used $CO_2$ in the mesophyll intercellular space for photosynthesis. In high VPD condition, The water potential values showed the highest at 5 a.m, and the lowest at 1 p.m in high VPD condition. The water saturation deficits (WSD) in high VPD condition showed about 1.5 times higher than in low VPD condition. The results indicated that physiological activities in Allium microdictyon is more limited from high VPD conditions.

• 한국재료학회지
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• 제21권9호
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• pp.509-514
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• 2011

In this study, optical emission spectroscopy was used to monitor the plasma produced during the RF magnetron sputtering of a $BaTiO_3$ target. The intensities of chemical species were measured by real time monitoring with various discharge parameters such as RF power, pressure, and discharge gas. The emission lines of elemental and ionized species from $BaTiO_3$ and Ti targets were analyzed to evaluate the film composition and the optimized growth conditions for $BaTiO_3$ films. The emissions from Ar(I, II), Ba(I, II) and Ti(I) were found during sputtering of the $BaTiO_3$ target in Ar atmosphere. With increasing RF power, all the line intensities increased because the electron density increased with increasing RF power. When the Ar pressure increased, the Ba(II) and Ti(I) line intensity increased, but the $Ar^+$ line intensity decreased with increasing pressure. This result shows that high pressure is of greater benefit for the ionization of Ba than for that of Ar. Oxygen depressed the intensity of the plasma more than Ar did. When the Ar/$O_2$ ratio decreased, the intensity of Ba decreased more sharply than that of Ti. This result indicates that the plasma composition strongly depends on the discharge gas atmosphere. When the oxygen increased, the Ba/Ti ratio and the thickness of the films decreased. The emission spectra showed consistent variation with applied power to the Ti target during co-sputtering of the $BaTiO_3$ and Ti targets. The co-sputtered films showed a Ba/Ti ratio of 1.05 to 0.73 with applied power to the Ti target. The films with different Ba/Ti ratios showed changes in grain size. Ti excess films annealed at $600^{\circ}C$ did not show the second phase such as $BaTi_2O_5$ and $TiO_2$.

• 한국항공우주학회지
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• 제40권4호
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• pp.300-308
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• 2012

무인기의 INS/GPS/기압고도계 결합항법 시스템에서 비행체 자체 항법 정보만을 이용하여 QNH 혹은 QFE 방식의 기압 고도계를 설정하는 방법을 제안한다. 본 설정 방법은 비행체 외부로부터 주어지는 대기나 고도 정보에 의존하지 않고 자체 항법 시스템의 정보만을 사용하며 설정 방법에 따라 요구되는 일정 형태의 비행을 통해 얻어진 정보를 수학적으로 처리하여 기준값을 산출한다. 비행체 자체 정보만을 사용함으로써 지상 지원 장비에서 대기 정보 측정 시스템을 제외하는 등 간소화나 지원 시설의 요구 조건이 완화될 수 있고 지상 지원이 가용하지 않는 영역에서의 비행도 가능하다. 특히 회귀 분석 기법을 이용한 방법은 고도와 기압, 온도의 세 가지 기준값을 설정함에 있어 고도와 기압, 두 가지 정보만을 요구하며 온도 자료가 필요하지 않다. 그러므로 기압 고도 산출에 온도 정보가 전혀 필요하지 않아 비행체의 대기 정보 측정 시스템도 간소화될 수 있다.

• 한국화재소방학회논문지
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• 제33권5호
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• pp.13-18
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• 2019

본 연구에서는 한국형발사체와 유사한 작동환경에서 Jet A1 액체연료의 매연 입자특성에 대해 농도를 측정함으로써 그 결과를 고찰하였다. 발사체환경과 유사한 대기 조건을 모사하기 위해 연소챔버의 산소 농도를 30%로 유지하고 내부 압력을 0.06 MPa에서 0.1 MPa 까지 변화시켜가며 실험을 통해 수행하였고, 대기의 조성을 질소, 헬륨, 이산화탄소 가스로 치환하여 실험을 수행하였다. 직경이 2 mm인 Jet-A1 액적에 동일한 점화에너지를 인가하여 발생 되는 매연 입자의 농도를 전역 광소멸 기법을 이용하여 측정하였다. Jet-A1 액적 화염의 매연 입자입자의 농도는 모든 압력조건에서 대기의 조성이 질소로 치환된 경우 높았으며, 이산화탄소로 치환된 경우 가장 낮았다. 압력이 낮아질수록 매연의 입자농도가 감소하였고, 대기압력의 Pⁿ 형태로 감소하는 경향을 확인하였다.

• 전기학회논문지
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• 제60권11호
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• pp.2083-2087
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• 2011

The SiC-$ZrB_2$ composites were produced by subjecting a 40:60 vol.% mixture of zirconium diboride($ZrB_2$) powder and ${\beta}$-silicon carbide (SiC) matrix to spark plasma sintering(SPS). Sintering was carried out for 60sec at $1400^{\circ}C$ (designation as TP145 and TP146), $1500^{\circ}C$(designation as TP155 and TP156) and uniaxial pressure 50MPa, 60MP under argon atmosphere. The physical, electrical, and mechanical properties of the SiC-$ZrB_2$ composites were examined. The relative density of TP145, TP146, TP155 and TP156 were 94.75%, 94.13%, 97.88% and 95.80%, respectively. Reactions between ${\beeta}$-SiC and $ZrB_2$ were not observed via x-ray diffraction (hereafter, XRD) analysis. The flexural strength, 306.23MPa of TP156 was higher than that, 279.42MPa of TP146 at room temperature, but lower than that, 392.30MPa of TP155. The properties of a SiC-$ZrB_2$ composites through SPS under argon atmosphere were positive temperature coefficient resistance (hereafter, PTCR) in the range from $25^{\circ}C$ to $500^{\circ}C$. The electrical resistivities of TP145, TP146, TP155 and TP156 were $6.75{\times}10^{-4}$, $7.22{\times}10^{-4}$, $6.17{\times}10^{-4}$ and $6.71{\times}10^{-4}{\Omega}{\cdot}cm$ at $25^{\circ}C$, respectively. The densification of a SiC-$ZrB_2$ composite through hot pressing depend on the sintering temperature and pressure. However, it is convinced that the densification of a SiC-$ZrB_2$ composite do not depend on sintering pressure under SPS.