• 공업화학
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• 제24권6호
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• pp.672-675
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• 2013

Medium-density fiberboard의 최적 열분해 조건을 찾기 위해 유동층 반응기를 이용하여 다양한 실험조건에서 급속열분해 실험을 수행하였다. 열분해 온도를 $425^{\circ}C$와 $575^{\circ}C$ 사이에서 변화시켰을 때, $525^{\circ}C$에서 최대 바이오오일 수율 52 wt%를 얻을 수 있었다. 열분해 온도가 높을수록 생성되는 바이오오일의 품질이 좋은 것으로 나타났다. 높은 온도에서 열분해 반응을 수행할 경우, 상당한 양의 oxygenates 및 acids 물질들이 분해되고, 대신 aromatics와 phenolics 같은 고부가가치 물질들이 생성되었다. 기체상 생성물의 대부분은 CO와 $CO_2$였다. 열분해 온도가 높을수록 CO와 $C_1-C_4$ 탄화수소 생성량이 많았다.

• 대한환경공학회지
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• 제27권11호
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• pp.1205-1214
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• 2005

본 논문은 중소형 규모의 도시고형 폐기물소각시설 배가스의 수은, 납, 비소, 셀렌과 같은 휘발성중금속의 방출특성을 조사하는데 있다. 대체로, 소형 도시고형 폐기물소각시설에서 배출되는 수은, 납, 비소, 셀렌이 중형 소각시설에서 배출되는 것 보다 높게 나타났다. 이는 중형소각시설에 비하여 소형소각시설의 빈약한 대기오염제어장치의 가동과 높은 배가스 온도에 기인하는 것으로 판단된다. 중소형 소각시설의 배가스 온도는 2개의 온도그룹으로 나누어지는 것을 확인할 수 있다. 첫 번째 온도그룹은 대략 $100^{\circ}C$이고, 두 번째 온도그룹은 $400{\sim}700^{\circ}C$ 정도였다. 2번째 그룹에서의 배가스 중 수은, 납, 비소, 셀렌은 각각 $70.43\;{\mu}g/Sm^3$, $0.94\;{\mu}g/Sm^3$, $9.83\;{\mu}g/Sm^3$, $5.05\;{\mu}g/Sm^3$였다. 첫 번째 온도그룹에서 배가스의 수은, 납, 비소 셀렌은 두 번째 온도그룹의 것보다 낮은 특징을 가지고 있다. 한편, 중형소각시설에서의 수은제거효율은 $55.16{\sim}95.89%$로 나타났다. 이러한 수은의 감소는 폐열보일러의 온도저감이 기여를 하고 있었다. 상기 결과로, 중소형 소각시설에서 휘발성 중금속 제어에 중요한 역할을 하는 것은 배가스의 온도가 큰 역할을 한다. 따라서, 휘발성 중금속의 제거효율을 개선하기 위해서는, 냉각시스템의 온도가 제어되고 대기오염제어장치가 잘 운영되어야 한다.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2007년도 춘계학술대회B
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• pp.2228-2231
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• 2007

Water gas shift reactor in fuel processing is an important part that converts carbon monoxide into hydrogen. Fuel processing system for PEMFC usually has two stages of WGS reactors, which are high temperature and low temperature shifter. In this study we prepared noble metal catalysts and compared their performances with that of a commercial iron chromium oxide catalyst. Noble metal catalysts and the commercial catalyst showed quite different temperature dependence of carbon monoxide conversion. The conversion of carbon monoxide at the commercial catalyst was very low at medium temperature(${\sim}300^{\circ}C$) and increased rapidly as temperature increased while the conversion at noble metal catalysts was high in the medium temperature range and decreased as temperature increased, which is thermodynamically expected. Their characteristics agreed well with the literature published, and we are accomplishing further study for improvement of the noble metal catalysts.

• 대기
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• 제34권1호
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• pp.23-34
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• 2024

The Korea Meteorological Administration has improved medium-range weather forecasts by implementing post-processing methods to minimize numerical model errors. In this study, we employ a statistical correction technique known as the minimum continuous ranked probability score (CRPS) to refine medium-range forecast guidance. This technique quantifies the similarity between the predicted values and the observed cumulative distribution function of the Unified Model Ensemble Prediction System for Global (UM EPSG). We evaluated the performance of the medium-range forecast guidance for surface air temperature and relative humidity, noting significant enhancements in seasonal bias and root mean squared error compared to observations. Notably, compared to the existing the medium-range forecast guidance, temperature forecasts exhibit 17.5% improvement in summer and 21.5% improvement in winter. Humidity forecasts also show 12% improvement in summer and 23% improvement in winter. The results indicate that utilizing the minimum CRPS for medium-range forecast guidance provide more reliable and improved performance than UM EPSG.

• Geomechanics and Engineering
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• 제21권5호
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• pp.461-469
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• 2020

The objective of this paper is to study the deformation in a homogeneous isotropic modified couple stress thermoelastic medium with and without energy dissipation and with two temperatures due to thermal source and mechanical force. Laplace and Fourier transform techniques are applied to obtain the solutions of the governing equations. The displacement components, stress components, conductive temperature and couple stress are obtained in the transformed domain. Isothermal boundary and insulated boundary conditions are used to investigate the problem.The effect of two temperature and GN theory of type-II and type-III has been depicted graphically on the various components. Numerical inversion technique has been used to obtain the solutions in the physical domain. Some special cases of interest are also deduced.

• 천문학회지
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• 제38권2호
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• pp.129-133
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• 2005

The temperature (T) and entropy (S) fields of baryonic gas, or intergalactic medium (IGM), in the ACDM cosmology are analyzed using simulation samples produced by a hybrid cosmological hydrodynamic/N-body code based on the weighted essentially non-oscillatory scheme. We demonstrate that, in the nonlinear regime, the dynamical similarity between the IGM and dark matter will be broken in the presence of strong shocks in the IGM. The heating and entropy production by the shocks breaks the IGM into multiple phases. The multiphase and non-Gaussianity of the IGM field would be helpful to account for the high-temperature and high-entropy gas observed in groups and clusters with low-temperature IGM observed by Ly$\alpha$ forest lines and the intermittency observed by the spikes of quasi-stellar object's absorption spectrum.

• 태양에너지
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• 제18권1호
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• pp.81-89
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• 1998

In this paper an experimental was done to design combustion chambers which is required radiation strength of high temperature generator of absorption rigerator. Partiqularly, in combustion chamber radiative mediums were set and basic experiments were done according to its size by radiation strength and effects of heat transfer promotion. The results are as follows : 1) When radiative mediums were set in small combustion furnace burning nonframely radiative heat transfer was effected. 2) In case that area ratio($A/A_o$) of radiative medium is 0.82 or over, temperature fluctuation effects of furnace inside were not nearly. 3) In experimental boundary heat transfer effects were 1.8 times by setting up radiative medium. Specially, $q/{\Delta}T$ values of furnace inside were uniformed nearly by setting up radiative mediums.

• Applied Science and Convergence Technology
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• 제23권6호
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• pp.371-375
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• 2014

Diffusion coefficient of Fe in polycrystalline host ZnSe as a mid-IR gain medium has been measured in the annealing temperature ranges of 850 to $950^{\circ}C$. The synthesis of the samples was carried out in quartz ampoule in which the Fe thin film deposited by physical vapor evaporation method on the ZnSe. One can realize that the diffusion coefficient strongly depends on the surface active surfactants through the cleaning process and the substrate temperature during the thin film deposition leading to $2.04{\times}10^{-9}cm^2/s$ for $Fe^{2+}:ZnSe$. The Annealing temperature dependence of the Fe ions diffusion in ZnSe was used to evaluate the activation energy, $E_a$=1.39 eV for diffusion and the pre-exponential factor $D_0$ of $13.5cm^2/s$.

• 설비공학논문집
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• 제13권11호
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• pp.1097-1105
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• 2001

The purpose of this study is to investigate the propriety of TMA clathrate as a cold storage medium. Particularly, this is to examine the extent of subcooling improvement when the additives are added to the TMA clathrate, because water used cold storage material has low phase change temperature and subcooling. This study has been analysed and compared with TMA 30 wt% clathrate how phase change temperature, subcooling and specific heat in the various concentrations are changed. This results view to be improved phase change temperature and subcooling of TMA 30 wt% as a cold storage medium, when it had some additive. Additional1y, it is found that the additive must be controlled under available solution limit and study for new additive must be lasted to know its effect.

• 태양에너지
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• 제20권3호
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• pp.1-9
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• 2000

In these days the hot water circulating Ondol using the fossil fuel boiler is the heating system for the most of the Korean residents. Then it is installed without the heat storage medium in the Ondol heating layer, but the Korean traditional Ondol had been composed with the heat storage medium. The Ondol room without heat storage medium could not be comfortable because the room air temperature is not only changed unstably but also it has a defect too much fuel consumption. Therefore in this study the heat pump-latent heat storage Ondol as the new type of Ondol system was developed to solve these problems mentioned above, and the COP of the heat pump (Coefficient Of Performance), the latent heat storage characteristics in the new type of Ondol system and the temperature variation in the Ondol room with the ambient temperature were analyzed.