• Applied Chemistry for Engineering
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• v.20 no.4
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• pp.411-415
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• 2009

To replace waste oil with the lowest grade which has high viscosity into heating fuel, light oil and buncker C oil in waste oil was used and the fuel characteristic was analyzed by its concentration after mixing oil. The mixture conditions were controlled by the reaction time (30 s~30 min) and kept by the reaction temperature ($75{\pm}5^{\circ}C$) when mixing speed was stirred at 3400~3600 rpm. We used the buncker C oil and light oil to decrease viscosity of waste oil and the dynamic viscosity was decreased by 81~96%. Optimum mixing ratio (waste oil : buncker C oil : light oil) as heating fuel was 1 : 1 : 1. Flash point, dynamic viscosity and heating value of this case were identified $78^{\circ}C$, $20.02mm^{2}/s$, 9158 kcal/L respectively.

• Journal of the Korean Society of Safety
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• v.27 no.5
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• pp.9-15
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• 2012

The ignition characteristics in a confined axisymmetric coflow $CH_4$ jet were investigated numerically with the Fire Dynamics Simulator(FDS). The $CH_4$ fuel stream was diluted with main combustion product gases, such as $O_2$, $N_2$, CO, $CO_2$, and $H_2O$, and the mixed fuel stream was heated up to the sufficient temperature where a supplying fuel stream can be ignited. For the calculation of chemical reaction in the simulation, a 2-step global finite chemistry model was considered. Boundary condition for confined wall was optimized by investigating the effects of wall temperature on the ignition characteristics of fuel stream. In addition, the effects of composition of diluents in the fuel stream and fuel stream temperature on the ignition of fuel steam were investigated. The ignition characteristics of $CH_4$ stream with diluents were very sensitive to the wall temperature, composition of diluents in the fuel stream and fuel stream temperature.

• Journal of Powder Materials
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• v.9 no.5
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• pp.315-321
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• 2002

Pure tantalum powder has been produced by combining Na as a reducing agent, $K_2TaF_{7}$ as feed material, KCl and KF as a diluent in a stainless steel(SUS) bomb, using the method of metallothermic reduction. The present study investigated the effect of the amount of the diluent and reaction temperature on the characteristics of tantalum powder in the production process. The temperature applied in this study $850^{\circ}C$ and the amount of the additional reductant from +5% of the theoretical amount used for the reduction of the entire $K_2TaF_{7}$. The results showed that as the amount of the diluent increased, the reaction temperature became lower because the diluent prevented a temperature rise. Also, according to the mixture ratio of the feed materials and the diluent changed from 1 : 0.25 to 1 : 2, the particle size decreased from $5\mutextrm{m}$ to $1\mutextrm{m}$ and a particle size distribution which is below 325 mesh in fined powder increases from 71% to 83%. The average size of Tantalum powder, $2-4\mutextrm{m}$, was close to that of the commercial powders($2-5\mutextrm{m}$). Also under this condition, impurities contained in the powder were within the range allowed for the commercial Ta powders.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2004.04a
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• pp.247-253
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• 2004

As a large scale port development in coastal waters proceeds step by step and populations in the vicinity of port are getting increased, the issue on "how to dispose the treated municipal water and wastewater in harbor" brings peoples′ concern. The submarine outfall system discharges the primary or secondary treated effluent at the coastline or in deep water, or between these two. The effluent, which has a density similar to that of fresh water, rises to the sea surface forming plume or jet, together with entraining the surrounding sea water and becomes very dilute. We intended in this paper to investigate the impact on dilution of effluent and the behavior of flume under the conditions of the seasonal and spatial temperature variations, which have not been noticeable in designing effective marine outfall system. To predict and analyze the behaviour and dilution characteristics of plume not just with the effluent temperature, but also with the seasonal variation of temperature of surround water and tidal changes, CORMIX(Cornell Mixing Zone Expert System)-GI have been applied. The results should be used with caution in evaluation the mixing zone characteristics of discharged water. We hope to help for the effective operation of outfall system, probable outfall design, protection of water quality, and warm water discharges from a power plant, etc.

• Microbiology and Biotechnology Letters
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• v.19 no.4
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• pp.398-404
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• 1991

- Ethanol production by calcium alginate-immobilized baker's yeast was studied in the continuous shaked-flask reactor (CSFR) using glucose medium as a feed. Immobilized cells were stable at 30~$37^{\circ}C$ and pH 4~8. Fermentation characteristics of immobilized baker's yeast were examined changing the initial glucose concentration employed were 50, 100 and 150 g/l, respectively. It was investigated that the influent glucose concentration and the dilution rate have an influence on the ethanol fermentation characteristics at steady state in continuous culture of immobilized baker's yeast. The optimum conditions for high ethanol productivity and low residual glucose output in ethanol prodution were shown to be 0.2 h ' for the dilution rate and 150 g/l for the influent glucose concentration. The maximum ethanol productivity, ethanol yield, specific growth rate and glucose conversion rate were around 7.12 g/$l\cdot h$, 0.23, 0.366 g/$l\cdot h$ and 78.43, respectively.

• Proceedings of the KIEE Conference
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• 1987.07b
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• pp.1163-1165
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• 1987

A novel temperature difference-to-frequency converter using two resistance temperature detectors (RTDs) has been developed. The resistance difference of two RTDs is converted into its equivalent inductance to form the resonant circuit of the Colpitts oscillator. The conversion sensitivity of $16\;Hz/^{\circ}C$ and the residual nonlinearity less than 2.15% over the temperature difference range from $35^{\circ}C$ to $155^{\circ}C$ are obtained by the prototype converter. The frequency drift of oscillator itself is ${\pm}0.5\;Hz$. Thus, the minimum detectable temperature difference is estimated to be ${\pm}0.013^{\circ}C$. The proposed converter, except for two RTDs, can be fabricated in monolithic IC form.

• Proceedings of the KSME Conference
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• 2001.11b
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• pp.155-160
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• 2001

The low NOx characteristics have been investigated to develop the combustor for micro turbine. The lean premixed combustion technology was applied to reduce the NOx emission. The test was conducted at the condition of high temperature and ambient pressure. The combustion air which has the temperature of $450\sim650K$ were supplied to the combustor through the air preheater. The temperature and emissions of NOx and CO were measured at the exit of combustor, The exit temperature and NOx were increased and CO was decreased with increasing inlet air temperature. The premixing chamber can be operated very lean condition of equivalence ratio around 0.35. The NOx was decreased with decreasing the equivalence ratio. The CO was decreased with decreasing the equivalence ratio, but the CO was increased with decreasing the equivalence ratio below 0.4. But, at the very lean condition of equivalence ratio below 0.35 both NOx and CO were increased because of the flame unstability. The NOx was decreased and CO was increased with increasing inlet air flowrate. This results can be used to determine the size of combustor. Consequently the performance of combustor shows the possibility of the application to the gas turbine system.

• Journal of Adhesion and Interface
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• v.14 no.4
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• pp.167-174
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• 2013

In this study, Ultraviolet (UV) curable urethane acrylates for ink binder was prepared by reaction of IPDI, polyether polyol and HEA. The UV curing behavior of compositions with HEA/PETA ratio on UV irradiation time was investigated by FT-IR spectrophotometer, probe tack tester and Photo-DSC. Conversion % and gel content were increased with increasing UV irradiation time, but probe tack was decreased. Storage modulus, tensile strength and decomposition temperature were increased as PETA content increased. In case of HEA/PETA ratio was 30/70, adhesion property of UV-cured composition on PMMA sheet was excellent.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 1999.10a
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• pp.87-89
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• 1999

본 연구에서는 Sorfactant/Cosolvent 혼합용액을 적용한 Soil flushing 기법에 의해 농약(Endosulfan(6,7,8,9,10,10-Hexachlor-1,5,5a,6,9,9a-hexahydro-6,9-methane-2,3,4benzo (e)dioxathiepin-3-oxide))으로 오염된 토양의 정화효율을 알아보았으며, 회분식 및 연속식 실험을 통하여 최적의 운전조건을 도출하고자 하였다. 세척용액의 적정 사용조건을 알아보기 위한 회분식 실험은 Jar tester를 사용하여 진탕비 (토양 중량 : 세척용액 부피), Surfactant(SDS ＋ POE$_{5}$, POE$_{9}$ ＋ POE$_{14}$, POE$_{5}$ ＋ POE$_{14}$, POE$_{14}$)와 보조용매(water, ethanol, methanol, ethanol＋methanol)의 혼합비 및 농도 조건을 변화시켜가며 토양세척을 수행하였다. 세척용액은 보조용매에 Surfactant의 농도를 0.5%, 1%로 용해하여 적용하였다. 연속식 실험은 회분식 실험에서 얻어진 최적 세척용액 사용조건 즉, 계면활성제 SDS + POE$_{5}$(1:1, 용액농도 1%), 보조용매 ethanol을 일정 비율로 혼합한 세척용액을 오염된 토양이 충진된 유리칼럼에 여러 유량조건에서 1 - 20 pore volume까지 통과시켜 각 통과된 pore volume에서의 토양세척 효율을 알아보았다. 본 실험조건에서 얻어진 세척용액의 최적 통과 속도는 0.31 ㎤$cm^{-2}$$min^{-1}$ 이었으며, 세척온도의 증가에 따른 세척효율의 향상은 2$0^{\circ}C$이상에서 크게 둔화되었다. 또한 보조용매의 사용량을 줄이기 위해 에탄올을 물로 1:3까지 희석한 결과 세척효율에 큰 영향이 없음을 알 수 있었다.

• Journal of the Korean Wood Science and Technology
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• v.22 no.2
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• pp.61-70
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• 1994

This study was executed to find the applicability of press drying of tree disk by investigating the shrinkage and drying defect and to form appropriate model by comparing the actual moisture content(MC) and internal temperature in respect of drying time with calculated values based computer simulation to which was applied finite difference method. In press drying disk, heating period, constant drying rate period maintained plateau temperature at 100$^{\circ}C$ and falling drying rate period were significantly distinguished. Actual MC and internal temperature were analogous to those calculated at comparing points. Heat transfer model formed by Fourier's law using specific heat of moist wood and conduction coefficient considering fractional volume of each element of wood cell wall, bound water, free water and air showed applicability as basic data to developing heat expansion, shrinkage and drying stress during press drying. Also mass transfer model formed by Fick's diffusion law using water vapor diffusion coefficient showed applicability. Longitudinal shrinkage was developed by pressure of hot press and tangential shrinkage was restrained by hygrothermal recovery. The heart check, surface check and ring failure were occurred differently in species, but V-shaped crack didn't develop.