• Transactions of the Korean Society of Automotive Engineers
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• v.5 no.1
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• pp.186-194
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• 1997

The objective of this study is to develope knock control algorithms which can increase engine power without causing frequent knock occurrence. A four cylinder spark-ignition engine is used for the experiments to develop knock control algorithms which use block vibration signals. Knock occurrence is detected accurately by using knock threshold values which consider the difference of transmission path of each cylinder. Spark timing is controlled both simultaneously and individually. With the simultaneous control, torque gain is achieved by retarding the spark timing on knock occurrence in propotion to the knock intensity. The individual knock control algorithm results in higher torque gain than the simultaneous knock control algorithm. The knock occurrence frequency of the individual knock control algorithm is about twice the value of the simultaneous knock control algorithm results. Both control algorithms give similar torque gain of about 3% when they are optimized.

• Transactions of the Korean Society of Automotive Engineers
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• v.6 no.5
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• pp.153-161
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• 1998

The knock in a spark ignition engine has been investigated to avoid the damage to the engine and unpleasant feeling caused by the pressure waves propagating across the combustion chamber. Knock intensity and knock onset angle were used as physical parameters to quantify the knock characteristics. The knock intensity is defined as a peak to peak value of the bank pass filtered combustion pressure signal and the knock onset angle is determined as the crank angle at which this signal exceeded the threshold level on each cycle. The cyclic variation of knock in four valve single cylinder engine was investigated with these two parameters. The location of autoignition was also examined by ion probes in the cylinder head gasket and squish region in the combustion chamber. For this measurement, a single cylinder engine was modified to accept the pressure transducer, 18 ion probes in the squish region and 8 ion probes in the specially designed PCB (Printed \ulcornerCircuit Board) cylinder head gasket.

• Journal of the korean Society of Automotive Engineers
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• v.14 no.5
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• pp.30-40
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• 1992

Spark knock obstructs any improvement in the efficiency and performance of an engine. As the knock mechanism of spark ignition engine, the detonation and the autoignition theory have been offered. In this paper, the knock model was established, which was able to predict the onset of knock and knock timing of spark ignition engine by the basis of autoignition theory. This model was a function of engine speed and equivalent air-fuel ratio. When this established knock model was tested from 1000rpm to 3000rpm of engine speed data, maximum error was crank angle 2 degrees between measured and predicted knock time. And the main results were as follows by the experimental analysis of spark knock in spark ignition engine. 1) Knock frequency was increased as engine speed increased. 2) Knock amplitude was increased as mass of end gas increased. 3) Knock frequency was occured above minimum 18% mass fraction of end gas.

• Journal of the korean Society of Automotive Engineers
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• v.14 no.5
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• pp.61-68
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• 1992

Knock phenomenon is an abnormal combustion originated from autoignition of unburned gas in the end-gas region during the later stage of combustion process and it accompanys a high pitched metallic noise. Engine Knock is accompanied with a vibration of engine cylinder and when it is severe, it can cause major engine demage. Engine Knock is characterized in terms of knock crank angle, knock pressure, pressure jump and knock intensity. In this study, a 4-cylinder spark ignition engine was used for experiment and eighty consecutive cycles were analyzed statistically. The purpose of this study is to characterize spark ignition engine knock as a function of ignition timing and fuel research octane number. The result of this study can be summerized as follows. Knock occurrence angle approached TDC as ignition timing is advanced. Pressure and knock intensity gradually increased as spark timing is advanced. Mean knock occurence angle gradually approached TDC as fuel research octane number is decreased for identical spark timing. Knock intensity increased linearly as RON is decreased.

• Reproductive and Developmental Biology
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• v.41 no.1
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• pp.7-16
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• 2017

The knock-in efficiency in the fibroblast is very important to produce transgenic domestic animal using nuclear transfer. In this research, we constructed three kinds of different knock-in vectors to study the efficiency of knock-in depending on structure of knock-in vector with different size of homologous arm on the ${\beta}-casein$ gene locus in the somatic cells; DT-A_cEndo Knock-in vector, DT-A_tEndo Knock-in vector I, and DT-A_tEndo Knock-in vector II. The knock-in vector consists of 4.8 kb or 1.06 kb of 5' arm region and 1.8 kb or 0.64 kb of 3' arm region, and neomycin resistance gene(neor) as a positive selection marker gene. The cEndo Knock-in vector had 4.8 kb and 1.8 kb homologous arm. The tEndo Knock-in vector I had 1.06 kb and 0.64 kb homologous arm and tEndo Knock-in vector II had 1.06 kb and 1.8 kb homologous arm. To express endostatin gene as transgene, the F2A sequence was fused to the 5' terminal of endostatin gene and inserted into exon 7 of the ${\beta}-casein$ gene. The knock-in vector and TALEN were introduced into the bovine fibroblast by electroporation. The knock-in efficiencies of cEndo, tEndo I, and tEndo II vector were 4.6%, 2.2% and 4.8%, respectively. These results indicated that size of 3' arm in the knock-in vector is important for TALEN-mediated homologous recombination in the fibroblast. In conclusion, our knock-in system may help to create transgenic dairy cattle expressing human endostatin protein via the endogenous expression system of the bovine ${\beta}-casein$ gene in the mammary gland.

• Journal of the korean Society of Automotive Engineers
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• v.15 no.1
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• pp.28-36
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• 1993

Present-day there are two of theories which have considerable scientific support to explain the knock phenomenon in S.I. engine, the detonation theory and the autoignition theory. But they still have some problems to explain effects of knock parameters, i.e.. compression ratio, spark timing, mixture quality, engine speed, ect, on knocking process in S.I. engine. Accordingly, it is essential to find out whish is more adequate theory of two and to develop the method of analyzing knock phenomenon, that is the aim of this paper. The Authors develop the method of predicting transient temperature and pressure at the end-gas zone during the combustion period and analyze knocking process by this method based on the knock theories. The caluculated values based on the autoignition theory show reasonablly correct relations between knock parameters and knock process but there is no evidence of knock occurred by detonation theory through the calculation according to the all parameters. The authors find out that the autoignition theory is more adequate than detonation theory to analyze knocking process in S.I. engine.

• Journal of the korean Society of Automotive Engineers
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• v.13 no.6
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• pp.57-64
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• 1991

Spart-ignition engine knock is an abnormal combustion phenomenon originated from auto- ignition of a portion of or the entire end-gas during the later stage of combustion process. And engine knock is accompanied by a vibration of engine cylinder block and a high-pitched metallic noise. Engine knock is characterized in terms of its intensity, its occurrence crank angel and the percentage of engine knock cycles. To characterize engine knock, a precise measurements of cylinder pressure and a statistical analysis of cylinder pressure data are needed. The purpose of this study is to develope a technique to measure engine knock and its characteristics as a function of ignition timing change. A 4-cylinder spark-ignition engine and unleaded gasoline, whose octane number was 94, were used for experiments. To measure engine knock and to analyze engine knock characteristics, cylinder pressure data were sampled by a high speed data acquisition system which was developed in this study. Cylinder pressure data were sampled at each 0.1.deg. crank angle and the number of cycles continuously sampled was 80.

• Journal of Microbiology and Biotechnology
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• v.28 no.12
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• pp.2009-2018
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• 2018

Leuconostoc mesenteroides can be used to produce mannitol by fermentation, but the mannitol productivity is not high. Therefore, in this study we modified the chromosome of Leuconostoc mesenteroides by genetic methods to obtain high-yield strains for mannitol production. In this study, gene knock-out strains and gene knock-in strains were constructed by a two-step homologous recombination method. The mannitol productivity of the pat gene (which encodes phosphate acetyltransferase) deletion strain (${\Delta}pat::amy$), the fk gene (which encodes fructokinase) deletion strain (${\Delta}fk::amy$) and the stpk gene (which encodes serine-threonine protein kinase) deletion strain (${\Delta}stpk::amy$) were all increased compared to the wild type, and the productivity of mannitol for each strain was 84.8%, 83.5% and 84.1%, respectively. The mannitol productivity of the mdh gene (which encodes mannitol dehydrogenase) knock-in strains (${\Delta}pat::mdh$, ${\Delta}fk::mdh$ and ${\Delta}stpk::mdh$) was increased to a higher level than that of the single-gene deletion strains, and the productivity of mannitol for each was 96.5%, 88% and 93.2%, respectively. The multi-mutant strain ${\Delta}dts{\Delta}ldh{\Delta}pat::mdh{\Delta}stpk::mdh{\Delta}fk::mdh$ had mannitol productivity of 97.3%. This work shows that multi-gene knock-out and gene knock-in strains have the greatest impact on mannitol production, with mannitol productivity of 97.3% and an increase of 24.7% over wild type. This study used the methods of gene knock-out and gene knock-in to genetically modify the chromosome of Leuconostoc mesenteroides. It is of great significance that we increased the ability of Leuconostoc mesenteroides to produce mannitol and revealed its broad development prospects.

• Asian-Australasian Journal of Animal Sciences
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• v.25 no.10
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• pp.1473-1480
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• 2012

The Galactose-${\alpha}1$,3-galactose (${\alpha}1$,3Gal) epitope is responsible for hyperacute rejection in pig-to-human xenotransplantation. Human decay-accelerating factor (hDAF) is a cell surface regulatory protein that serves as a complement inhibitor to protect self cells from complement attack. The generation of ${\alpha}1$,3-galactosyltransferase (GGTA1) knock-out pigs expressing DAF is a necessary step for their use as organ donors for humans. In this study, we established GGTA1 knock-out cell lines expressing DAF from pig ear fibroblasts for somatic cell nuclear transfer. hDAF expression was detected in hDAF knock-in heterozygous cells, but not in normal pig cells. Expression of the GGTA1 gene was lower in the knock-in heterozygous cell line compared to the normal pig cell. Knock-in heterozygous cells afforded more effective protection against cytotoxicity with human serum than with GGTA1 knock-out heterozygous and control cells. These cell lines may be used in the production of GGTA1 knock-out and DAF expression pigs for xenotransplantation.

• Transactions of the Korean Society of Automotive Engineers
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• v.5 no.3
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• pp.202-208
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• 1997

The knocking is one of major parameters to improve engine performance in a spark ignition engine. Many researches have been carried out to identify them using cylinder pressure, vibration signal and so on. In the present study, measurement and analysis was conducted to set up the criteria of knock occurrence by using microphone signal. Cylinder pressure was measured for the reference signal of knocking. It has been observed that resonance frequencies of pressure wave are nearly independent of engine operating conditions such as engine speed, air fuel ratio, load and octane number of fuel within to limited experimental conditions. SDBP(sum of different band-pass data) method using resonance frequency of knock was proposed for estimating knock intensity. SDBP method is superior to identify knock occurrence and its intensity in case of sound pressure measurement.