• International Journal of Automotive Technology
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• 제2권2호
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• pp.63-75
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• 2001

This paper describes the development of THC reduction technologies compliant with SULEV regulations. Technologies embodied by the developmental work include improvement of fuel spray atomization, quick warm-up through coolant control shut of, and acceleration of fuel atomization for the fast rise of cylinder head temp inside the water jacket as well as the improvement of combustion state. The technologies likewise entail reduced HC while operating in lean A/F condition during engine warm-up with the cold lean burn technology, individual cylinder A/F control for improvement of catalytic converting efficiency, after-treatment such as thin-wall catalyst, HC-adsorber and EHC and etc, through vehicle application evaluation in cold start. We carried out an experimental as well as a practical study against SULEV regulations, and the feasibility of adopting these items in vehicle was likewise investigated.

• Korean Chemical Engineering Research
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• 제50권5호
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• pp.802-807
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• 2012

본 연구에서는 메탄으로부터 합성가스를 만드는 자열 개질(Autothermal reforming)반응 특성을 Ni (15 wt%)-Ru (1 wt%)/$Al_2O_3$-MgO 금속모노리스 촉매체와 전기 발열식 촉매를 사용하여 조사하였다. 자체 가동 형 반응기는 자열 개질 반응기에 $700^{\circ}C$ 반응물을 공급하는데 걸리는 start-up 시간이 2분 이내였다. 반응물의 $O_2/CH_4$와 $H_2O/CH_4$ 비가 메탄의 전환율과 반응기의 온도 분포에 미치는 영향은 매우 크다. 반응기의 온도는 $H_2O/CH_4$ 비가 감소할수록 흡열반응에서 발열반응으로 전환되어 증가한다. 또한 $H_2O/CH_4$ 비가 증가함에 따라 수성가스화 전이반응에 의하여 생성물 중에 $CO_2$양이 증가한다. $GHSV=10,000\;h^{-1}$, 반응물 조성($H_2O/CH_4=0.6$과 $O_2/CH_4=0.5$)의 자열 개질반응에서, 97%의 메탄의 전환율을 얻었으며, 반응기의 온도는 $600^{\circ}C$로 유지되었다. 이 반응조건에서 170 cc 금속모노리스 촉매체를 충진한 반응기에서 자열개질 반응으로 생성된 최대 합성가스의 유량은 $0.94\;Nm^3/h$ 이었다.

• 공업화학
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• 제27권5호
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• pp.532-536
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• 2016

본 연구에서는 하수 슬러지를 대상으로 단상 고온($55^{\circ}C$)과 중온($35^{\circ}C$) 혐기성 소화조의 안정성, 고형물 제거 및 메탄생성을 관찰하였다. 실험 결과 별도의 pH 조절 없이 고온($R_{TAD}$, reactor of thermophilic anaerobic digestion) 및 중온 ($R_{MAD}$, reactor of mesophilic anaerobic digestion) 소화조 내 pH의 경우 혐기 소화 시 안정적인 미생물 활성을 나타낸다고 알려진 6.5-8.0 사이의 값을 소화 기간 내내 유지하는 것을 관찰할 수 있었다. 또한, total alkalinity (TA)의 경우 $R_{TAD}$ 및 $R_{MAD}$ 모두 3-4 g $CaCO_3/L$의 높은 값을 안정적으로 유지하였다. 고형물 제거의 경우 순응 기간 후 $R_{TAD}$에서 43.3%, $R_{MAD}$에서 33.6%의 VS 제거율을 보이며 $R_{TAD}$에서 약 10% 높은 VS 제거율은 제거율을 보였다. 유기산의 경우 $R_{TAD}$ 및 $R_{MAD}$에서 순응 기간 직후 검출되지 않았다. $R_{TAD}$ 및 $R_{MAD}$ 모두 순응 기간 후 안정적인 메탄 생성을 보였으며, $R_{TAD}$에서 $R_{MAD}$에 비해 31.4% 향상된 메탄 생성률이 관찰되었다($R_{TAD}$; 243 mL $CH_4/L/d$; $R_{MAD}$ : 185 mL $CH_4/L/d$). 반면, 두소화조 $R_{TAD}$ 및 $R_{MAD}$에서의 메탄 수율은 유사한 값을 보였다.

• 한국주조공학회지
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• 제25권2호
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• pp.73-79
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• 2005

Effects of Cr and Ni addition on damping capacity, mechanical property, and corrosion resistance of Fe-17%Mn martensitic alloy have been studied. Martensite start temperature($M_{S}$) of the alloy decreases linearly with increasing Cr and Ni contents up to 15%. The damping capacity decreases gradually from 27 to 22% in specific damping capacity(SDC) with increasing Cr and Ni contents from zero to 10%, and decreases rapidly with further Cr and Ni content in Fe-17%Mn alloy. The tensile strength of the alloy maintains a level of 60 $kgf/mm^{2}$ regardless of Cr content with an elongation of 20 to 25%. But, in case of Fe-17%Mn-x%Ni alloy, the tensile strength decreased rapidly with the Ni content of above 10% because of austenite morphology. Immersion test in 5% NaCl solution leads to the result that the corrosion resistance of the alloy becomes excellent above 10% Cr. From the above results, it is concluded that the optimum Cr content to improve the mechanical property and corrosion resistance of the alloy in 5%NaCl solution with a lesser decrease in damping capacity is about 10%. In the case of 5% $H_{2}SO_{4}$ condition, the Fe-17%Mn-10%Ni is an optimum alloy.

• 대한화학회지
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• 제7권2호
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• pp.96-105
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• 1963

The weight decrease curves of 18 kinds of polymers have been measured by thermobalance at the same condition where temperature is increased $1^{\circ}C$ per minutes under nitrogen or air atmosphere. The curves are further differentiated to obtain rate curve of weight decrease. Those curve offer a method to compare relative thermal stability, effects of oxygen or modes of thermal degradation of polymers qualitatively. The curves could be classified into following four types: Polystyrene, polymethylmethacrylate and acetal polymer belong to the first type. Those polymers depolymerize mainly into corresponding monomers, weight decrease curves are steepy up to perfect vaporization of polymers and rate curves show a relatively sharp peak. (Type I) Polyvinyl chloride represents the second type. This polymer decomposes with splitting off of hydrogen chloride. The thermogravimetric curve rises rapidly at first, then level off at the moderate weight decrease and gradually rises. Polyvinyl acetate also belongs to this class. (Type II) The modification of the second type is represented by polyester. The curve at the early stage is less steep, the leveling off at the next stage is less clear and the final rising of the curve is steeper than the normal second type. Polyamide, polyurethane, and polycarbonate belong to this type. (Type II') The thermal decomposition of the third type polymers is more complex than that of others. Various irregular chain scissions including side chain splitting and depolymerization to monomers occur simultaneously. The weight of the polymer decreases gradually and the rate curve does not show sharp peaks. Polyvinyl alcohol and diene polymers belong to this type. (Type III) Generally, polycondensation polymers are more stable toward heat than addition polymers and polymers having aromatic nucleus show good thermal stability. Polymers having tertiary carbon atoms such as polystyrene or polypropylene and acetal resin start decomposition under airatmosphere at the temprature below $50^{\circ}C$ or more of the temperature where the polymers start decomposition under nitrogen atmosphere.

• 항공우주시스템공학회지
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• 제14권5호
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• pp.91-99
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• 2020

액체로켓엔진은 발사 전까지 성능의 입증을 위해 많은 시험을 거친다. 점화 및 시동 조건 설정을 위한 시험이나 정격 조건에서의 성능시험을 통해 설계 성능을 검증한다. 하지만 개발과정에서 여러 작동조건의 시험을 통해 탈설계 조건에서의 성능확인이 필요하며 이는 엔진 개발기간에 영향을 준다. 엔진 내의 제어 밸브의 개도를 변화시키는 엔진 성능 시험과 함께 엔진으로 공급되는 추진제의 조건을 변경시켜 탈설계 성능 시험을 수행한다. 본 논문에서는 나로우주센터에 설치되어 있는 한국형발사체 액체로켓 엔진 시험설비에서 수행된 엔진 시험 운용 결과를 기초로 하고 있으며, 시험 대상체에 공급되는 추진제의 압력과 온도의 변화로 터보펌프의 입구 조건을 변경시키는 탈설계 조건 성능시험을 위한 시험설비 운용에 관한 내용을 기술하였다.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2008년 영문 학술대회
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• pp.109-114
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• 2008

This paper presents the development status of a subscale precooled turbojet engine "S-engine" for the hypersonic cruiser and space place. S-engine employs the precooled-cycle using liquid hydrogen as fuel and coolant. It has $23cm{\times}23cm$ of rectangular cross section, 2.6 m of the overall length and about 100 kg of the target weight employing composite materials for a variable-geometry rectangular air-intake and nozzle. The design thrust and specific impulse at sea-level-static(SLS) are 1.2 kN and 2,000 sec respectively. After the system design and component tests, a prototype engine made of metal was manufactured and provided for the system firing test using gaseous hydrogen in March 2007. The core engine performance could be verified in this test. The second firing test using liquid hydrogen was conducted in October 2007. The engine, fuel supplying system and control system for the next flight test were used in this test. We verified the engine start-up sequence, compressor-turbine matching and performance of system and components. A flight test of S-engine is to be conducted by the Balloon-based Operation Vehicle(BOV) at Taiki town in Hokkaido in October 2008. The vehicle is about 5 m in length, 0.55 m in diameter and 500 kg in weight. The vehicle is dropped from an altitude of 40 km by a high-altitude observation balloon. After 40 second free-fall, the vehicle pulls up and S-engine operates for 60 seconds up to Mach 2. High altitude tests of the engine components corresponding to the BOV flight condition are also conducted.

• Journal of international Conference on Electrical Machines and Systems
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• 제3권4호
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• pp.428-432
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• 2014

Rotating machines are an integral part of large electrical power machinery in most of the industries. Any degradation or outages in the rotating electric machinery can result in significant losses in productivity. It is critical to monitor the equipment for any degradation's so that it can serve as an early warning for adequate maintenance activities and repair. Prior research and field studies have indicated that the rotating machines have a particular type of signal structure during the initial start-up transient. A machine performance can be studied based on the effect of degradation in signal parameters. In this paper a data-acquisition system and the FFT algorithm has been design and model using the MATLAB and Simulink. The implementation had been carried out on the TMS320 DSP Processor and various testing and verification of the machine performance had been carried out. The results show good agreement with expected results for both simulated and real-time data. The real-time data from AC water pumps which have rotating motors built-in were collected and analysed. The FFT algorithm provides frequency response and based on this frequency response performance of the machine had been measured.The FFT algorithm provides only approximation about the machine performances.

• 한국대기환경학회지
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• 제31권5호
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• pp.461-471
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• 2015

Base on emission factors derived from National Institute of Environmental Research, Particulate matter from combined cycle power plants (CCPPs) has been estimated to be a important source of $PM_{10}$. Generally there is no serious emission of particulate matter in CCPPs. because the fuel of them is natural gas. But emission gas after long shut down season has very high dust content. Therefore $PM_{10}$ emission rate is dependent on its operation mode. In this study, particulate dispersion study for new city near CCPPs complex has performed using CALPUFF model for three case. $PM_{10}$ concentration has big difference between normal operation and 2 case start-up condition after long shutdown. In normal operating conditions, daily $0.32{\sim}0.50{\mu}g/m^3$ influence on of the surrounding area. But when 1~2 aerobic high concentration discharged conditions, average concentration is higher about $9.2{\sim}34.1{\mu}g/m^3$ than normal operating conditions.

• 제어로봇시스템학회논문지
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• 제2권4호
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• pp.306-311
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• 1996

This paper discusses the maintenance of the water level of steam generators at its programmed value. The process, the water level of a steam generator, has the nonminimum phase property. So, it causes a reverse dynamics called a swell and shrink phenomenon. This phenomenon is severe in a low power condition below 15 %, in turn makes the start-up of the power plant too difficult. The control algorithm used here incorporates a pole-assignment scheme into the minimum variance strategy and we use a parallel adaptation algorithm for the parameter estimation, which is robust to noises. As a result, the total control system can keep the water level constant during full power by locating closed-loop poles appropriately, although the process has the characteristics of high complexity and nonlinearity. Also, the extra perturbation signals are added to the input signal such that the control system guarantee persistently exciting. In order to confirm the control performance of a proposed pole-assignment self-tuning controller we perform a computer simulation in full power range.