• Journal of Energy Engineering
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• v.8 no.1
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• pp.150-158
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• 1999

본 연구는 저온플라즈마를 이용하여 배기가스중의 SOx와 NOx를 동시에 처리하는 공정을 개발하는 것으로서, 최적의 반응제 선정과 효율적인 공정의 구성을 위해 SOx, NOx와 반응제와 반응기구를 밝히고자 하였다. 실험은 1.0 N㎥/h의 모사가스를 이용한 기초실험과 20 N㎥/h의 실제 연소가스를 이용한 실험으로 진행되었으며, 반응제로는 NH3와 파리핀계 및 올레핀계 탄화수소를 사용하였다. NH3를 반응제로 한 SO2 제거반응은 비플라즈마 조건에서는 NH4HSO3, 플라즈마 조건에서는 (NH4)2SO4의 생성반응이었고, 두 조건 모두 높은 제거율을 나타냈다. 반응제를 사용하지 않은 플라즈마 조건에서 SO2는 환원반응이 일어나고 O2 농도의 증가는 역반응을 증가시키는 화학평형에 의해 SO2의 제거율이 감소되었다. 플라즈마 조건에서 NO는 O2농도가 낮은 경우는 NO의 환원반응이 주로 일어나고, O2 농도가 높을 경우는 산화반응이 지배적이었다. 올레핀계 탄화수소는 플라즈마 조건에서 NO 산화 반응에 탁월한 효과를 보였을 뿐만 아니라 SO2 제거에도 효과를 보여 최대 40%의 제거율을 나타냈으며, NH3의 사용을 줄일 수 있음을 확인하였다.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.8 no.1
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• pp.111-115
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• 1970

1. Eight Varieties of Nicotiana tabacum, "Yellow special A", "Gold leaf", "Oxford, " "Awha", "Yungzung", "Samsun", "Maruha" and "Hatano" were compared on the photoperiodic responses. 2. Experiments were conducted both under high temp. condition(green-house, average temp $25^{\circ}C$-$35^{\circ}C$) and low temp. condition (out-door; average temp $10^{\circ}C$-$25^{\circ}C$) in four plots of 8.10.12 and 14 hours in day length. 3. The results obtained are summarized as follows; i) In the short day condition, the flowering was accelerated in the low temp. than high. On the contrary, in the high temp, it was accelerated in the long day. ii) Generally speaking, the flowering was responsed more in low temp. and short day length than high temp.-long day. iii) But the above trend was found great difference among varieties..-long day. iii) But the above trend was found great difference among varieties.

• Proceedings of the Korean Vacuum Society Conference
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• 2014.02a
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• pp.217.1-217.1
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• 2014

반도체 및 디스플레이 산업은 많은 공정들에서 저온 플라즈마 반응을 이용한다. 특히 소자 제작을 위한 실리콘 박막의 증착은 저온 플라즈마 공정의 주요 공정이다. 하지만 실리콘 박막을 합성하는데 있어서 저온 플라즈마에서 형성되는 실리콘 나노 입자는, 오염입자로써 박막의 특성을 악화시켜 소자생산 수율을 악화시키는 주요 원인이 되고 있다. 따라서 플라즈마에서 입자 형성의 원인이 되는 화학반응 및 입자들의 성장 매커니즘에 대한 연구는, 1980년대 플라즈마 공정에서 입자 합성이 보고된 이래 공정의 최적화를 위해 꾸준히 연구되어왔다. 이러한 매커니즘의 연구들은, 플라즈마 화학반응에 의해 실리콘 입자 핵을 만들어 내는 과정과 입자들이 충돌에 의해 성장해가는 과정으로 나눠진다. 플라즈마 화학 반응 과정은 아레니우스 방정식에 의해 정의된 반응계수를 이용하여 플라즈마 내 전자와 이온, 중성 화학종들이 전자 온도와 전자 밀도, 챔버 온도 등에 의해 결정되는 현상을 모사한다. 또한 이 과정에서 실리콘을 포함하는 화학종들의 반응에 의해 핵이 생성 되가는 양상을 모사한다. 생성된 핵은 충돌에 의해 입자가 성장해 가는 과정의 가장 작은 입자로써 이용된다. 입자들이 성장해가는 과정은 입자들이 서로 충돌하면서 다양한 입경의 입자로 분화되어가는 현상을 모사한다. 이 과정에 의해 다양한 입경분포로 분화된 입자들은 플라즈마 내 전자에 의해 하전되며, 이러한 하전 양상은 입경에 따라 다른 분포를 보인다. 본 연구에서는 입자의 하전 분포를 고려하여, 입자들의 성장의 주요 원인인 입자간의 충돌을 대표하는 충돌주파수를 수정하는 방식을 채택하여 보다 정밀한 입자 성장 양상을 모델링하였다. Inductively coupled plasma (ICP) 타입의 저온 플라즈마 반응기에서 합성된 입자들을 Particle Beam Mass Spectrometer (PBMS)와 Scanning Electron Microscope (SEM)를 이용하여 입경분포를 측정한 데이터와 모델링에 의해 계산된 결과를 비교하여 본 모델의 유효성을 검증하였다. 검증을 위해 100~300 mtorr의 챔버 압력 조건과 100~350 W의 입력 전력 조건들을 달리하며 측정한 결과와 계산한 데이터를 조건별로 비교하였다.

• Journal of Aerospace System Engineering
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• v.13 no.4
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• pp.18-25
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• 2019

Studies on the fabrication of UAV by using 3D printer have been actively carried out. However, research on structural load characteristics in low temperature environment is insufficient. In this study, a composite sandwich structure with ordinary orbs structure was proposed, and the load characteristics for temperature condition changes were analyzed. The ordinary orbs and honeycomb structures were fabricated by using a FDM type 3D printer. The bending load test was carried out at room temperature and low temperature condition. The low temperature condition was classified into four cases. Bending load tests were performed in a low temperature chamber to maintain the required temperature conditions. As a result of the test, it was confirmed that the proposed ordinary orbs structure had better load characteristics at low temperatures than the existing honeycomb structure.

• Transactions of the Korean Society of Mechanical Engineers
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• v.9 no.2
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• pp.213-221
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• 1985

Two dimensional laminar natural convection in a rectangular enclousure composed of a hot bottom wall, a partially cold side wall and insulated walls except the above walls was studied by numerical analysis and also by esperiments. In the experiments, the temperature distributions in the enclosure and Nusselt number distribution along the hot and cold walls were obtained by the use of Mach-Zehnder interferometer. At first, numerical analysis with the boundary conditions of the experimental apparatus was performed and the comparison of the results of the numerical and the experimental results validated the numerical model good ennough. Heat transfer characteristics were investigated by applying the verified numerical model with the parameters, i.e. Grashof number, aspect ratio, position of cold plate and insulation condition. The results showed the optimal conditions of temperature distribution and the position of cold wall, and the characteristics of insulation materials.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2008.11a
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• pp.153-156
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• 2008

Ignition and combustion performance of a gas-turbine engine were changed by various high-altitude condition. A goal of this study is to make the small test facility to simulate high-altitude condition. To perform the low pressure condition, a diffuser was used in various diffuser front of primary nozzle pressure. To perform the low temperature, heat exchanger was used in various mixture ratio of cryogenic air and ambient temperature air. The experimental result shows that high-altitude conditions can be controled by diffuser front of primary nozzle pressure and mixture ratio of cryogenic air and ambient temperature air.

• Applied Chemistry for Engineering
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• v.17 no.4
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• pp.409-413
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• 2006

An experimental study on a combined $De-NO_x$ process of non-thermal plasma and $NH_{3}$ SCR, which can be operated under low temperature conditions, i.e. $150{\sim}200^{\circ}C$, has been conducted. The test results confirmed feasibility of fast SCR reaction, which shows faster reactivity compared with typical SCR reaction under the low temperature conditions. The test showed that pre-oxidation step to convert NO to $NO_2$ is necessary for the fast SCR reaction, and the appropriate ratio of $NO_{2}/NO_{x}$ ranges from 0.3 to 0.5. Ammonium salts produced under low temperature conditions, effects of hydrocarbons on the combined process, the operation power of the process are discussed in the present study.

• Journal of the Korean Society of Industry Convergence
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• v.6 no.1
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• pp.17-21
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• 2003

5원환 고리아세탈 화합물인 4-methylenes(4,5)을 합성하고 저온조건 하에서 중합반응을 조사한 결과, 선택적인 개환중합이 일어났다. 보통의 양이온 개시제를 사용한 결과 $-78^{\circ}C$에서 가교체가 얻어졌으며, $CH_3SO_3H$를 개시제로 사용하면 같은 조건에서도 주사슬과 곁사슬에 이중결합을 가지는 개환중합체가 얻어진다. 이 중합체는 반응성을 가지는 불포화기를 포함하고 있으므로 prepolymer로써 널리 사용될 수 있다.

• The Korean Journal of Soil Zoology
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• v.5 no.2
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• pp.119-123
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• 2000

Effect of fluctuating temperatures on the development of the immature beet armyworm, Spodoptera exigua (H bner), was analyzed. At constant rearing temperature regimes, the estimated developmental threshold temperatures were varied among stages and instars, but had an average 13$^{\circ}C$ from egg hatch to adult emergence. Based on the 13$^{\circ}C$ threshold temperature, we set up three different rearing temperature regimes having the same day-degrees. Two fluctuating temperature regimes changed significantly the developmenta1 period expected by the constant rearing temperature regime. Under the same thermophase temperature (25$^{\circ}C$), the thermocycling regime with the higher cryophase temperature (10$^{\circ}C$) decelerated the developmental rate probably by lowering temperature limit thor development, but that with the lower cryophase temperature (5$^{\circ}C$) gave a negative developmental effect.

• Korean Journal of Weed Science
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• v.11 no.3
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• pp.205-210
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• 1991

The freezing resistance of Eleocharis kuroguqai was evaluated in artifical and natural freezing conditions in relation to tuber size, depth of tuber burial and soil moisture conditions. Osmotic potential of immature and mature tuber of E. kuroguqai before hardening was -12.1 and -23.5 bar, respectively, but decreased to -61. 0 and -67.1 bar after 120-day hardening period. Percent survival of E. kuroguqai tubers during the winter period was 13% and 67% in dry and moist moisture conditions at burial of 5cm depth, but all tubers were survived in the three moisture conditions employed when buried at 25cm depth. Greater decrease of osmotic potential was observed in tubers buried at 5cm depth than tubers buried at 25cm depth, resulting in greater freezing resistance in the former. Large tuber was more susceptable to freezing temperatures than small tuber.