• 한국자동차공학회논문집
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• 제24권3호
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• pp.345-351
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• 2016

This study was carried out to determine an optimal lean $NO_x$ trap (LNT) regeneration condition based on a $NO_x$ storage fraction. The LNT regeneration was performed by an in-cylinder post fuel injection method. A $NO_x$ storage fraction is defined by the ratio of current cumulated $NO_x$ amount in the LNT to the $NO_x$ storage capacity: 0 means empty and 1 fully loaded. In this study five engine operating conditions were chosen to represent the New European Driving Cycle. With various $NO_x$ storage fractions each engine operating condition, the LNT regeneration was executed and then $NO_x$ conversion efficiency, additional fuel consumption, CO and THC slip, peak catalyst temperature were measured. The results showed that there exist an optimal condition to regenerate the LNT, eg. 1500 rpm 6 bar BMEP with below 0.7 $NO_x$ storage fraction in this experimental constraint.

• 한국자동차공학회논문집
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• 제22권2호
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• pp.60-66
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• 2014

A control oriented model of the Lean $NO_x$ trap (LNT) was developed to determine the timing of $NO_x$ regeneration. The LNT model consists of $NO_x$ storage and reduction model. Once $NO_x$ is stored ($NO_x$ storage model), at the right timing $NO_x$ should be released and then reduced ($NO_x$ reduction model) with reductants on the catalyst active sites, called regeneration. The $NO_x$ storage model simulates the degree of stored $NO_x$ in the LNT. It is structured by an instantaneous $NO_x$ storage efficiency and the $NO_x$ storage capacity model. The $NO_x$ storge capacity model was modeled to have a Gaussian distribution with a function of exhaust gas temperature. $NO_x$ release and reduction reactions for the $NO_x$ reduction model were modeled as Arrhenius equations. The parameter identification was optimally performed by the data of the bench flow reactor test results at space velocity 50,000/hr, 80,000/hr, and temperature of $250-500^{\circ}C$. The LNT model state, storage fraction indicates the degree of stored $NO_x$ in the LNT and thus, the timing of the regeneration can be determined based on it. For practical purpose, this model will be verified more completely by engine test data which simulate the NEDC transient mode.

• 한국자원식물학회지
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• 제12권3호
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• pp.198-203
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• 1999

콩 저장 단백질의 대부분은 globulin이며, 이중 7S와 11S가 70% 이상을 차지한다. 따라서 콩 단백질의 조성개량을 위해서는 11S/7S비율 조정이 우선되는데, 본 연구에서는 전기영동(SDS-PAGE)법을 사용하여 콩 단백질 7S와 11S를 분리 확인하고, 이들 분획 단백질의 유전변이를 분석하였다. 국내 3개지역에서 재배된 콩 장려품종 6계통들의 평균 7S 함량은 38.9% 이었고 11S는 61.2%의 함량을 나타내었다. 분산분석 결과 품종간에 는 유의성이 있었지만 지역간에는 변이가 없었으며, 품종 x 지역의 상호작용은 고도의 유의성을 나타내었다. 유전력은 7S분획중의 $\beta$함량이 72.7%로 높게 나타났다. 공분산을 이용한 상관계수 추정에서는 유전상관이 표현형 상관 보다 다소 높게 나타났다. 따라서 7S와 11S의 분획간 함량을 조정함으로써 콩 단백질의 조성을 개량할 수 있으리라 판단된다.

• 한국자동차공학회논문집
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• 제22권5호
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• pp.13-19
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• 2014

Urea-SCR system is the selective catalytic reduction to reduce nitrogen oxides ($NO_x$) emitted from diesel vehicles. The objective of this study is numerical analysis of 3-dimensional unsteady melting problems of frozen urea by using an electric heater. It can be applied to determine capacity of power with respect to time and the location of the urea suction pipe in urea storage tank. The study includes the change of liquid volume fraction, temperature profiles and a influence of natural convection by using the commercial software STAR-CCM+(v7.06). The accuracy of the numerical analysis is estimated by comparisons with experimental data. After validation, a numerical analysis for freezing urea is conducted with four different heating power. From the results, it was found that relation of velocity of phase interface and amount of melting urea by increasing heating power in a container. There is also a difference in trend between velocity of phase interface and amounts of melting urea because of effect of natural convection.