• Journal of Mechanical Science and Technology
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• v.18 no.8
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• pp.1451-1460
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• 2004

A two-stroke Schnurle-type gasoline engine was modified to enable compression-ignition in both the port fuel injection and the in-cylinder direct injection. Using the engine, examinations of compression-ignition operation and engine performance tests were carried out. The amount of the residual gas and the in-cylinder mixture conditions were controlled by varying the valve angle rate of the exhaust valve (VAR) and the injection timing for direct injection conditions. It was found that the direct injection system is superior to the port injection system in terms of exhaust gas emissions and thermal efficiency, and that almost the same operational region of compression-ignition at medium speeds and loads was attained. Some interesting combustion characteristics, such as a shorter combustion period in higher engine speed conditions, and factors for the onset of compression-ignition were also examined.

• Transactions of the Korean Society of Automotive Engineers
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• v.3 no.6
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• pp.123-133
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• 1995

An injection control valve(ICV) was designed to control the fuel flow between a common rail and an injector with two commercial solenoids. To improve the performance of ICV, the characteristic method was applied. With this method, the flow characteristics in the ICV and the injector were studied and the parameters which affect the injection characteristics were also studied. From this study, following results were obtained. The injection duration can be controlled and with modifications of the effective valve stroke of ICV, the injection quantity and duration can be reduced to desired amount. Also the injection quantity and pressure can be controlled by reducing the hole size of the injector without the variation of the injection duration. For some conditions, the desired injection characteristics can be obtained by the changes of the valve timing, the effective valve stroke, the open pressure of the injector and the hole size of the injector.

• Journal of Animal Environmental Science
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• v.13 no.1
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• pp.29-34
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• 2007

This study was conducted to develop a reclaimer of the vehicle disinfector to be used at livestock fm. The reclaimer was mainly consisted of ball-valves, geared motors and one-chip processor, and the purpose of the system was to prevent liquid freezing as well as decrease environmental pollution of antiseptic solution. The properly spraying pressure of the vehicle disinfector was found over 1.96 MPa at 1m of the spraying range. While certain amount of the antiseptic solution remained in the injection-pipes, the spray starting time was found not making any significant effect on the remained amount of the antiseptic solution. The amounts of the antiseptic solution remained in the injection-pipes were 50 ml and 270 ml in average, respectively with and without the use of the reclaimer. The reclaimer was the most effective when the connection of the injection-pipe and sprayer line was located below the side-injection-pipe and then connected to the injection-pipe located at the bottom of vehicles.

• Transactions of the Korean Society of Automotive Engineers
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• v.14 no.3
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• pp.178-185
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• 2006

This paper investigates the steady-state combustion characteristics of the Homogeneous charge compression ignition(HCCI) engine with variable valve timing(VVT) and dimethyl ether(DME) direct injection, to find out its benefits in exhaust gas emissions. HCCI combustion is an attractive way to lower carbon dioxide($CO_2$), nitrogen oxides(NOx) emission and to allow higher fuel conversion efficiency. However, HCCI engine has inherent problem of narrow operating range at high load due to high in-cylinder peak pressure and consequent noise. To overcome this problem, the control of combustion start and heat release rate is required. It is difficult to control the start of combustion because HCCI combustion phase is closely linked to chemical reaction during a compression stroke. The combination of VVT and DME direct injection was chosen as the most promising strategy to control the HCCI combustion phase in this study. Regular gasoline was injected at intake port as main fuel, while small amount of DME was also injected directly into the cylinder as an ignition promoter for the control of ignition timing. Different intake valve timings were tested for combustion phase control. Regular gasoline was tested for HCCI operation and emission characteristics with various engine conditions. With HCCI operation, ignition delay and rapid burning angle were successfully controlled by the amount of internal EGR that was determined with VVT. For best IMEP and low HC emission, DME should be injected during early compression stroke. IMEP was mainly affected by the DME injection timing, and quantities of fuel DME and gasoline. HC emission was mainly affected by both the amount of gasoline and the DME injection timing. NOx emission was lower than conventional SI engine at gasoline lean region. However, NOx emission was similar to that in the conventional SI engine at gasoline rich region. CO emission was affected by the amount of gasoline and DME.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.34 no.1C
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• pp.98-104
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• 2009

Tone injection scheme has been known as one of PAPR(Peak to Average Power Ratio) reduction methods deployable to multi-carrier system like OFDM(Orthogonal Frequency Division Multiplexing). The basic idea in tone injection scheme is to enforce the constellation size larger so that each of original constellation points is mapped into the preassigned distinct points. Along the accomplishment of tone injection, it needs great amount of computations to search out not only an appropriate frequency but a phase. Although there is no loss of transmission rate is expected because of no need to send the overhead, the tone injection scheme has not been preferable due to its enormous computations. To alleviate the amount of complexity, this paper proposes the GA(Genetic Algorithm) based tone injection scheme such that its complexity is reduced comparing with that of the conventional method. The simulation results show that the proposed GA based tone injection scheme approaches the PAPR performance associated with the conventional exhaustive search method at the expense of low computations.

• Korean Journal of Agricultural Science
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• v.45 no.4
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• pp.725-732
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• 2018

The vaccination for foot-and-mouth disease (FMD) is an effective way to control FMD. However, the injection of FMD vaccine causes abnormalities in pork meat by the incidence of lesions at the injection site. This study was conducted to investigate the inhibition effects of dietary bromelain, a natural protease derived from pineapple stems, on the incidence of lesions at the vaccination site on pigs. A total of 335 pigs (LYD [Landrace ${\times}$ Yorkshire ${\times}$ Duroc]; 7-week-old) were randomly allotted to two dietary treatments: control (basic diet) and bromelain treatment (diet supplemented with bromelain 1 kg/ton). The injection of FMD vaccine was conducted on 56- and 84-day-old pigs. Pigs with the bromelain treatment were fed a diet supplemented with bromelain for 14 days from 5 days before the vaccine injection. After slaughtering the pigs, the number of carcasses that had abnormal meat at the injection site of the vaccine and the amount of abnormal meat, discarded meat, and trimmings were recorded. Pork from the bromelain treated pigs had a lower incidence of abnormal meat caused by vaccine injection as well as a lower amount of abnormal meat, discarded meat, and trimmings than those of the control (p < 0.05). Our result suggests that dietary bromelain could improve the quality of pork meat by inhibiting incidence of lesions at the vaccine injection site.

• Journal of the Korea Convergence Society
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• v.12 no.1
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• pp.127-132
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• 2021

The intravenous injection monitoring system used by medical institutions was developed to remotely provide patients with the amount of intravenous injected and the termination point of the injection. In order to measure the amount of intravenous injection input, the weight or flow rate of the level going out from the inside to outside of the intravenous injection can be observed with a measuring sensor. The criteria for devices that apply herein are accuracy and vigilance. In addition, it is compact and should be easy to use when installing intravenous injection on patients. In medical institutions, the accuracy of the measured values must be high, and economically inexpensive devices are required. In this study, low-cost small-weight-centered load cell sensors were applied, and algorithms were applied to reduce the artefact by external movement by converging with gyro sensors for accuracy of measurements. As a result, it was possible to reduce the error of measurement, thereby improving the accuracy of the intravenous injection monitoring measurement value.

• Transactions of the Korean Society of Automotive Engineers
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• v.12 no.5
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• pp.40-57
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• 2004

The effects of triple (pilot, main and after) injection on combustion and emission characteristics in a HSDI (High-Speed Direct Injection) diesel engine were investigated using a single-cylinder optical diesel engine equipped with a common-rail injection system. The pilot injection affected the spray and combustion evolution of the following main injection. It was found that the pilot injection reduced the ignition delay, which led to lowered NOx (Nitric Oxides) level, and increased IMEP (Indicated Mean Effective Pressure) due to slow combustion pace during an expansion stroke. The after-injection was shown to be effective in reducing PM (Particulate Matter) even when a small amount of fuel was added. The results suggest that a proper combination of individual injection strategy could bring about a good synergetic effect on engine performance and emission.

• Transactions of the Korean Society of Automotive Engineers
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• v.22 no.3
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• pp.1-11
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• 2014

The aim of this study is to investigate the effect of SCR reactor on the exhaust emissions characteristics in order to develop a urea-SCR aftertreatment system for reducing $NO_x$ emissions. The experiments are conducted by using a flue tube LPG steam boiler with the urea-SCR aftertreatment system. The urea-SCR aftertreatment system utilizes the ammonia converted from 17% aqueous urea solution injected in front of SCR catalyst as a reducing agent for reducing $NO_x$ emissions. The equivalence ratio, urea injection amount, ammonia slip and $NO_x$ conversion efficiency relative to boiler load are applied to discuss the experimental results. In this experiment, the average equivalence ratio is calculated by changing only the fuel consumption rate while the intake air amount is constantly fixed at $25,957.11cm^3/sec$. The average equivalence ratios are 1.38, 1.11, 0.81 and 0.57 when boiler loads are 100, 80, 60 and 40%. The $NO_x$ conversion efficiency is raised with increasing urea injection amount, and $NH_3$ slip is also boosted at the same time. Consequently, the $NO_x$ conversion efficiency relative to boiler load should be examined in combination with urea injection amount and $NH_3$ slip. The results are calculated by 89, 85, 77 and 79% for the boiler loads of 100, 80, 60 and 40%. The appropriate amount of urea injection for the respective boiler load can be not discussed by only $NO_x$ emissions, and should be determined by considering the $NO_x$ conversion efficiency, $NH_3$ slip and reactive activation temperature simultaneously. In this study, the urea amounts of 230, 235, 233 and 231 mg/min are injected at the boiler loads of 100, 80, 60 and 40%, and the final $NH_3$ slips are measured by 8.48, 5.58, 11.97 and 11.34 ppm at the same conditions. THC emission is affected by the SCR reactor under other experimental conditions except 100% engine load, and CO emission at only 40% engine load. The rest of exhaust emissions are not affected by the SCR reactor under all experimental conditions.

• Journal of the Society of Naval Architects of Korea
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• v.40 no.3
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• pp.9-15
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• 2003

An experimental study has been carried out as a basic research for development of the friction drag reduction technology for ships by polymer injection. Experimental apparatus and procedures have been devised and prepared to measure the changes of the wall friction with injection of a polymer solution and basic experimental data on the friction drag reduction are obtained for a turbulent fiat-plate boundary layer and fully-developed channel flows. Variations of the friction drag reduction with some important parameters of polymer injection, such as the concentration of polymer solution, its injection flow rate and the measuring position downstream from the injection slot, are also investigated. Important experimental data and results obtained in the present study are presented. The amount of friction drag reduction up to 50% is observed.