• 한국신재생에너지학회:학술대회논문집
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• 2007.11a
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• pp.569-572
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• 2007

천연가스의 주요 구성성분은 메탄, 에탄, 프로판으로 99%이상 차지하고 있으며 천연가스 하이드레이트(NGH)는 압축천연가스(CNG)에 비해 체적당 질량이 크고 액화천연가스(LNG) 보다 상대적으로 유리한 온도 및 압력조건으로 인해 천연가스의 경제적인 저장 및 수송 수단으로 주목 받고 있다. $CH_4$ - $C_2H_6$, $CH_4$ - $C_3H_8$ 혼합가스 하이드레이트의 제조시 반응시간에 따른 하이드레이트의 거동을 관찰하였으며 생성조건의 변화에 따른 하이드레이트의 생성속도를 비교하였다. 하이드레이트의 생성이 진행될 때 기상에서의 $C_2H_6$, $C_3H_8$의 몰 비는 감소함을 보여주었고 이러한 변화는 $CH_4$ - $C_3H_8$가 $CH_4$ - $C_2H_6$보다 더욱 빠르게 진행되었다. 또한 생성된 하이드레이트의 해리과정이 진행될 때 역시 서로 다른 해리속도에 의해 조성의 변화를 관찰 할 수 있었다.

• Journal of Korean Society of Environmental Engineers
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• v.36 no.2
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• pp.103-108
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• 2014

Using dried sludge as a secondary fuel of a coal-fired power plant is proposed as an alternative option for sludge disposal. Because elemental contents of sludge are different from those of coal, different levels of acidic gas emissions are expected from the co-combustion of sludge with coal. In this study, sludge samples were obtained from 7 sewage treatment plants in Korea. Each sludge sample was combusted together with coal in a lab-scale combustor, and the concentrations of nitrogen oxides ($NO_x$), sulfur dioxide ($SO_2$), hydrogen chloride (HCl), chlorine ($Cl_2$) in the flue gas were analyzed. Compared to the combustion of coal only, $NO_x$ concentration was slightly higher in the flue gas from the co-combustion of coal and sludge. $SO_2$ emission increased with the combustion of sludge due to the higher content of sulfur in sludge than in coal. For most of the tested samples, the concentrations of HCl and $Cl_2$ were varied depending on the chlorine content in the sludge sample.

• Korean Journal of Food Science and Technology
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• v.18 no.1
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• pp.66-70
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• 1986

Storability of strawberry in air with the different levels of $CO_2$, for CA storage were measured. The strawberries stored in air included 20% and 30% $CO_2$, for 5 weeks decayed 14% and 10%, respectively, while the decay rate of the strawberries stored in normal air for 2 weeks was 53%. Firmness and 'a' value in Hunter Color Measuring Scale of the strawberries kept in the CA storage conditions were superior to those of the strawberries stored in normal air during storage. The concentrations of ethyl alcohol and acetaldehyde were increased with storage period and they were less in the strawberries in air with 30% $CO_2$, than those of the strawberries stored at the other conditions.

• Journal of IKEEE
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• v.23 no.2
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• pp.704-709
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• 2019

In this paper, the electrical characteristics of tunneling field effect transistor(TFET) was studied for different annealing conditions. The TFET samples annealed using hydrogen forming gas(4 %) and Deuterium($D_2$) forming gas(4 %). All the measurements were conducted in noise shielded environment. The results show that subthreshold slope(SS) decreased by 33 mV/dec after annealing process compared to before annealing. Under various temperature range, the noise is improved by average of 31.2 % for 10 atm Deuterium gas at $V_G=3V$ condition. It is also noticed that, post metal annealing with $D_2$ gas reduces the noise by average of 30.7 % at $I_D=100nA$ condition.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.34 no.12
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• pp.1043-1050
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• 2010

Fuel stratification and thermal stratification occur in the HCCI combustion chamber on a microscopic scale. They affect the ignition and combustion processes. In this study, the effect of the inhomogeneity in the mixture gas on the HCCI combustion process was investigated. Two-dimensional chemiluminescence images were captured using a framing camera to evaluate the flame structure. DME was used as the test fuel. First, the effect of inhomogeneity in the fuel distribution in the premixture was investigated for the four-stroke optically accessible engine. Then, by comparing the combustion of the homogeneous mixture in the rapid compression machine, which does not contain any residual gas, with the combustion in the four-stroke engine, the effect of inhomogeneity in temperature due to the residual gas was analyzed. The results showed that a time lag appears spatially in combustion under inhomogeneous conditions in the four-stroke engine. The spatial variation in the combustion without the residual gas in the rapid compression machine is less than that in the combustion in the four-stroke engine.

• Journal of the Korean Institute of Gas
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• v.7 no.4 s.21
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• pp.1-6
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• 2003

Freon gas has been replaced with LPG in the cosmetic industry because of its bad effects on environment. In this paper, skincare product with a cooling effect was developed using LPG as propellant. A cooling effect is obtained by the ice which is formed through spraying. Ice formation is affected by the composition of LPG and most of all, the high content of propane gas in the LPG results in the irregular surface of ice formed because of its high vapor pressure. Also the ratio of LPG to skincare solution affects the formation of ice.

• Journal of Korean Society of Environmental Engineers
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• v.29 no.6
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• pp.647-653
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• 2007

The ultimate objective of this study is to develop a reliable oxygen-enriched combustion techniques especially for the case of the flue gas recycling in order to reduce the $CO_2$ emissions from practical industrial boilers. To this end a systematic numerical investigation has been performed, as a first step, for the resolution of the combusting flame characteristics of lab-scale LNG combustor. One of the important parameters considered in this study is the level of flue gas recycling calculated in oxygen enriched environment. As a summary of flame characteristics, for the condition of 100% pure $O_2$ as oxidizer without any flue gas recycling, the flame appears as long and thin laminar-like shape with relatively high flame temperature. The feature of high peak of flame temperature is explained by the absence of dilution and heat loss effects due to the presence of $N_2$ inert gas. The same reasoning is also applicable to the laminarized thin flame one, which is attributed to the decrease of the turbulent mixing. These results are physically acceptable and consistent and further generally in good agreement with experimental results appeared in open literature. As the level of $CO_2$ recycling increases in the mixture of $O_2/CO_2$, the peak flame temperature moves near the burner region due to the enhanced turbulent mixing by the increased amount of flow rate of oxidizer stream. However, as might be expected, the flue gas temperature decreases due to presence of $CO_2$ gas together with the inherent feature of large specific heat of this gas. If the recycling ratio more than 80%, gas temperatures drop so significantly that a steady combustion flame can no longer sustain within the furnace. However, combustion in the condition of 30% $O_2/70% $ $CO_2$ can produce similar gas temperature profiles to those of conventional combustion in air oxidizer. An indepth analyses have been made for the change of flame characteristics in the aspect of turbulent intensity and heat balance.

• Proceedings of the IEEK Conference
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• 1998.06a
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• pp.409-412
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• 1998

BCl/sub 3/ 및 Cl/sub 2/ 반응가스를 사용하여 RIE 장치로 GaN의 건식식각을 연구하였다. RF 전력, 반응가스의 유량 및 반응가스의 혼합비 등의 변화에 따른 최적의 식각공정 조건 및 결합특성을 연구하였다. RF 전력에 따른 GaN의 식각율은 챔버압력 25mTorr, BCl/sub 3/ 유량 40 sccm의 조건에서 RF 전력이 100W일때 17nm/min을 얻었다. BCl/sub 3/의 유량에 따른 식각율은 RF 전력 100W 챔버압력 20mTorr, Cl/sub 2/ 유량 5sccm의 조건에서 BCl/sub 3/ 유량이 40 sccm일때 65nm/min을 얻었다. Cl/sub 2//BCl/sub 3/ 혼합가스 비율에 따른 식각율은 Cl/sub 2/ 유량을 5sccm으로 고정하고 BCl/sub 3/ 유량을 변화시켰을때 RF 전력 100W 및 챔버압력 20mTorr의 조건에서 혼합비가 0.25일때 50nm/min을 얻었다. RF 전력에 따른 PR의 식각율은 챔버압력 25mTorr, Cl/sub 2/ 유량 0 sccm 및 BCl/sub 3/ 유량 40 sccm의 조건에서 RF 전려이 100W일때 15nm/min을 얻었다. 또한, 챔버압력 20mTorr, Cl/sub 2/ 유량 5 sccm 및 BCl/sub 3/ 유량 20sccm의 조건에서 RF 전력이 100W 일때 82nm/min을 얻었다.

• Proceedings of the Korea Society for Energy Engineering kosee Conference
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• 1994.05a
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• pp.9-14
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• 1994

알카리금속염 (K$_2$CO$_3$, $K_2$SO$_4$). 알카리 토금속염 (Ba(NO$_3$)$_2$), 철족금속염(Ni(NO$_3$)$_2$, FeSO$_4$) 으로 이루어진 여러가지 혼합물들이 반응온도 700~85$0^{\circ}C$ 하의 촤-수증기 가스화반응에서 나타내는 촉매활성을 열천칭 반응기를 사용하여 측정하였다. 비촉매 가스화반응에서 초기반응성은 수증기 분압에 비례하였다. 촉매 가스화반응에서 단일염 촉매의 경우 $K_2$CO$_3$ 가 가장 큰 활성을 나타내었으며, 다른 염들은 낮은 활성을 보였다. 혼합염의 경우 $K_2$SO$_4$에 철족염을 부가함에 따라 반응속도가 향상되었으며, $K_2$SO$_4$+Ni(NO$_3$)$_2$가 가장 큰 촉매활성을 나타내었다. $K_2$SO$_4$와 Ni(NO$_3$)$_2$ 의 촉매 활성은 담지량에 따라 증가하며, 석탄의 등급에 따라 감소하였다. $K_2$SO$_4$와 Ni(NO$_3$)$_2$의 혼합비는 같은 몰비로 혼합하였을때 가장 큰 활성을 나타내었다.

• Journal of the Korean Vacuum Society
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• v.2 no.3
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• pp.368-373
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• 1993

LCVD법에 의한 박막성장장치를 제작하였다. 제작한 CO2 레이저는 CO2 : N2 : He이 1 : 1 : 8로 혼합된 가스를 사용하였으며 최대 출력은 60W였고 혼합가스의 유량이 20l/min, 방전전류 40mAdlfEo 50W의 비교적 안정된 출력을 얻을 수 있었다. 반응실의 기초 진공은 1$\times$10-6torr였으며 레이저를 기판에 수직 혹은 수평으로 조사할 수 있도록 설계하였다. 제작된 장치로 SiH4 및 NH3를 재료로 하여 실리콘 및 quartz 기판위에 silicon nitride 박막을 증착하였다. 박막 생장시 가스를 흘리는 방식보다 가스를 채워놓고 하는 방식이 낮은 레이저 출력하에서 균일한 박막을 얻는데 효율적이라는 것을 발견하였다. 출력 55W의 레이저를 실리콘 기판에 5분간 조사하였을 때 최대 두께1.5$mu extrm{m}$의 박막을 얻었으며 quartz 기판위에는 출력 4W, 조사시간 6분에서 두께가 약 1$\mu\textrm{m}$인 비교적 균질의 박막을 얻을 수 있었다. FT-IR 및 XPS 분석 결과 SiH4와 NH3의 혼합비가 1 : 12일 때 비교적 nitride화가 잘 된 박막이 얻어졌음을 알았다.