• Journal of the Korean Professional Engineers Association
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• v.4 no.15
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• pp.11-15
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• 1971

Bunker C fuel oil may be taken as a conc. solution of asphalt as a solute. It may be assumpt that there will be unalogical relationship between cone. solution and solute in regological behavior. Investigation was carried out to fiud out the -opitimum preheating temperature. The following results were obtained: the colloidal structure bunker C fuel oil undergoes a transition at around the softening point of the solute asphalt: and the flow charactor changes from non-Newtonian flow to Newtonian as well as its activation energy is memarkably reduced at around softening point of the solute asphalt for the purpose of the improvement of flow charater of Bunker C fuel oil, the preheating must be done above the softening point of a solute asphalt.

• Journal of Energy Engineering
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• v.24 no.3
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• pp.89-95
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• 2015

Carbon felts manufactured by (Co)CNF were subjected to heat treatment under different temperatures to use for the electrode of a redox-flow battery. BET and weight loss were tested to investigate the physical properties of the carbon felt according to the heat treatment conditions. SEM and XPS were also analyzed to characterize their surface area. In addition, electrical resistance, CV (cyclic voltammetry) and RFB charge on the electrode properties were examined in accordance with the heat treatment conditions with the discharge performance. The changes of physical properties on the carbon felt surface was confirmed via SEM and BET analysis, The most addition of oxygen functional groups on the carbon felt surface was obtained when one hour heat treatment at $550^{\circ}C$ and it was confirmed by XPS analysis. After resulting the CV tests, the active area of the electrode was the largest at $550^{\circ}C$ heat treatment. The heat treatment experiment of vanadium redox flow battery using the carbon felts were tested at $400^{\circ}C$, $500^{\circ}C$ and $550^{\circ}C$. As a result, the charge-discharge energy efficiency of the heat treatment electrode was 72.9% and 79.8%, at $400^{\circ}C$ and $500^{\circ}C$, respectively. The efficiency of the heat treatment electrode at $550^{\circ}C$ was the best as 79.8% at $550^{\circ}C$.

• Journal of Biosystems Engineering
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• v.35 no.1
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• pp.64-68
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• 2010

Cattle feedlot manure could be used effectively as the solid fuel for heating of agricultural facilities. Therefore, this study was carried out to investigate the thermal and physicochemical characteristics of solid fuel extruded with cattle feedlot manure. Calorific values of the solid fuel extruded with cattle feedlot manure, which was dried to the moisture contents of 0.0% (w.b) and 35.0% (w.b,) were 14,906 kJ/kg and 11,797 kJ/kg, respectively. Calorific value of extruded solid fuel was linearly decreased with the increase of moisture content. The first, second, and third reaction point during thermal pyrolysis of solid fuels extruded with cattle feedlot manure was investigated as $108.1^{\circ}C$, $312.2^{\circ}C$, and $459.4^{\circ}C$, respectively. The maximum reaction point was presented at the temperature of $312.2^{\circ}C$. Weight loss of extruded cattle feedlot manure during thermal pyrolysis until $600^{\circ}C$ was reached to about 60%. Volume decrease of initial extruded cattle feedlot manure was 61% during drying for the use as solid fuel. Maximum strength of extruded cattle feedlot manure, which was dried as the moisture content of 10% (w.b.) was 41,9150 N/$m^2$. Ignition gas analysis of extruded cattle feedlot manure presented that it has small amount of $NO_x$ and $SO_x$. It was shown that dried cattle feedlot manure had main components of C and O including small amount of Mg, Si, and Ca.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.38 no.2
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• pp.155-163
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• 2014

At gas stations, liquid fuels expand and contract in volume owing to temperature variations. In Korea, the ambient temperature varies between $-15^{\circ}C$ in winter and $35^{\circ}C$ in summer. The volume expansion coefficients of liquid fuels are about $0.1%/^{\circ}C$. To investigate this issue, we measured daily changes in fuel temperature and the delivered fuel temperature at gas stations. In addition, we scrutinized the daily, monthly, and annual changes in temperature over past 50 years in Korea. The results show that the temperature of the fuel in the storage tank was maintained at a stable value(summer or winter). Many factors, such as the surrounding conditions, fuel filling frequency, and gas station location, influence the delivered fuel temperature. The results of this study can be applied for establishing a national regulation and will contribute to fair transactions.

• Journal of Korean Society of Water and Wastewater
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• v.29 no.1
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• pp.57-63
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• 2015

Recently, Korea's municipal wastewater treatment plants generated amount of wastewater sludge per day. However, ocean dumping of sewage sludge has been prohibited since 2012 by the London dumping convention and protocol and thus removal or treatment of wastewater sludge from field sites is an important issue on the ground site. The hydrothermal carbonization is one of attractive thermo-chemical method to upgrade sewage sludge to produce solid fuel with benefit method from the use of no chemical catalytic. Hydrothermal carbonization improved that the upgrading fuel properties and increased materials and energy recovery, which is conducted at temperatures ranging from 200 to $350^{\circ}C$ with a reaction time of 30 min. Hydrothermal carbonization increased the heating value though the increase of the carbon and fixed carbon content of solid fuel due to dehydration and decarboxylation reaction. Therefore, after the hydrothermal carbonization, the H/C and O/C ratios decreased because of the chemical conversion. Energy retention efficiency suggest that the optimum temperature of hydrothermal carbonization to produce more energy-rich solid fuel is approximately $200^{\circ}C$.

• Journal of Information Processing Systems
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• v.1 no.1 s.1
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• pp.36-40
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• 2005

TRISO (Tri-Isotropic)-coated fuel particle is widely applied due to its higher stability at high temperature and its efficient retention capability for fission products in the HTGR (high temperature gas-cooled reactor), one of the highly efficient Generation IV reactors. The typical ball-type TRISO-coated fuel particle with a diameter of about 1 mm is composed of a nuclear fuel particle as a kernel and of outer coating layers. The coating layers consist of a buffer PyC, inner PyC, SiC, and outer PyC layer. In this study, a digital image processing algorithm is proposed to automatically measure the thickness of the coating layers. An FBP (filtered backprojection) algorithm was applied to reconstruct the CT image using virtual X-ray radiographic images for a simulated TRISO-coated fuel particle. The automatic measurement algorithm was developed to measure the coating thickness for the reconstructed image with noises. The boundary lines were automatically detected, then the coating thickness was circularly by the algorithm. The simulation result showed that the measurement error rate was less than 1.4%.

• Korean Journal of Materials Research
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• v.8 no.8
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• pp.766-774
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• 1998

32$0^{\circ}C$, 40%NaOH 용액의 autoclave에서 약 300wppm의 탄소를 함유하고 있는 15Cr-9Fe-balanced Ni 합금 판상시편에 대해 응력부식 저항성을 조사하였다. 부식시편은 $700^{\circ}C$, 100시간 동안의 열처리로 합금내부에 석출될 수 있는 가능한 한 많은 양의 크롬계 탄화물을 석출시킨 후, 다시 재용해에 의해 크롬계 탄화물의 형태를 조절하는 $800^{\circ}C$-$950^{\circ}C$범위의 최종열처리를 시행하고 급냉시킨 다음 U-자형으로 응력을 가하여 준비되었다. 최종열처리 온도가 올라감에 따라 시편들의 입계응력부식균열(IGSCC ) 전파속도는 $900^{\circ}C$까지는 거의 직선적으로 증가하다가 $950^{\circ}C$에서는 $700^{\circ}C$에서 얻은 값보다도 더 낮게 감소하였다. 즉, 크롬계 탄화물이 재용해되어 그 밀도가 감소함에 따라 IGSCC저항성이 감소하다가 완전히 재용해된 $950^{\circ}C$ 열처리 조건에서 오히겨 가장 큰 IGSCC 저항성을 나타내었다. 이와같은 최조열처리 온도에 따른 니켈계 합금 600의 부식거동은 입계에 존재하는 크롬계탄화물의 형태변화 때문이 아니라 입계에서 탄소-크롬계 탄화물-크롬간의 상평형에 의해 이루어지는 탄소의 입계편석량이 크롬계탄화물이 존재할 때에는 열처리 온도에 따라 증가하다가 그것이 완전히 재용해 되었을 때 가장 낮아지기 때문인 것으로 생각된다.

• Korean Chemical Engineering Research
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• v.49 no.6
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• pp.786-789
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• 2011

In order to estimate the possibility of applying electrolytes generally used in solid oxide fuel cells(SOFCs) to direct carbon fuel cells(DCFCs), properties of YSZ(yttria stabilized zirconia) electrolyte were evaluated. In this study, vacuum slurry coating method was adapted to coat thin layer on anode support substrate. After sintering the electrolyte at $1400^{\circ}C$ for 5hrs, microstructure was analyzed by using SEM image. Also, gas permeability and ionic conductivity were measured to find out the potential possibility of electrolyte for DCFCs. The YSZ electrolyte represented dense coating layer and low gas permeability value. The ionic conductivity of YSZ electrolyte was high over $800^{\circ}C$. After measurement of the electrolyte properties, direct carbon fuel cell was fabricated and its performance was measured at $800^{\circ}C$.

• Journal of the Korean Wood Science and Technology
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• v.35 no.2
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• pp.23-28
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• 2007

Wood fuel must be dried before combustion to minimize the energy loss. Sawdust of Japanese red pine was dried in a direct contact thermal screw dryer to investigate the drying characteristics of sawdust as a raw material for bio-fuel. Average drying rate and energy efficiency was 1.4%/min and 69.23% at $100^{\circ}C$, respectively, and those at $120^{\circ}C$ was 2.1%/min and 71.03%, respectively.

• Transactions of the Korean Society of Automotive Engineers
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• v.10 no.3
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• pp.101-110
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• 2002

In this paper, the effects of oxygen component in blended fuel on the exhaust emissions have been investigated far direct injection diesel engine. It was tested to estimate change of engine performance and exhaust emission characteristics for th? commercial diesel fuel and oxygenated blended fuels which have three kinds of fuels and various mixed rates. And, it was tried to analyze not only total hydrocarbon but individual hydrocarbons(C$_1$∼ C$\_$6/) in exhaust gases using gas chromatography to seek the reason far remarkable reduction of smoke emission on various oxygenated fuels. This study carried out by comparing the chromatogram with diesel fuel and diesel fuel blended DGM(diethylene glycol dimethyl ether), MTBE(methyl tart-butyl ether) and EGBE(ethylene glycol mono-n-butyl ether). The results of this study show that individual hydrocarbons as well as total hydrocarbon of oxygenated fuel are reduced remarkably compared with commercial diesel fuel.