• 한국분무공학회지
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• 제12권3호
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• pp.166-171
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• 2007

Recently, many studies on HSDI diesel engines have been performed to reduce the fuel consumption and $CO_2$ emission. One of the prominent technique to reduce emission is a high pressure multiple injection. For this technique, the injection rate is a critical parameter in order to determine precise injection duration and timing for combustion control. Thus the purpose of this study was to investigate relationship between the injection rate and the time-signature of chamber pressure at different injection pressure conditions in a common rail direct injection type injector using the Zeuch method. Using the measured correlation constants, estimated fuel injection rates are presented at many different injection conditions.

• 한국분무공학회지
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• 제15권1호
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• pp.8-16
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• 2010

This paper present the diesel spray characteristics at different injection system parameters in a HSDI diesel engine. The spray characteristics was calculated by the coupled simulation of fuel injection system model and three-dimensional KIVA-3V code with TAB spray model. The relevant injection parameters are accumulator volume, control chamber initial volume, control orifice diameter, needle valve diameter and nozzle chamber initial volume, etc. Parametric investigation with respect to twelve relevant injection parameters showed that there was a significant advantage in varying control chamber initial volume, control chamber orifice diameter, and nozzle chamber orifice diameter with respect to effect the SMD and fuel injection speed. Consequently, in order to design the fuel injection system for spray characteristics, it seems reasonable to suppose to be optimized the fuel injection system.

• International Journal of Automotive Technology
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• 제7권5호
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• pp.527-534
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• 2006

Modern passenger cars with diesel engines are equipped with DOC(diesel oxidation catalyst) for the purpose of reducing HC and CO in the exhaust stream. Cold start exhaust emissions pose troubles here as on gasoline engine vehicles. As a result, some of the diesel passenger cars roll off todays the assembly lines with WCC(warm-up catalytic converter). Oxidation characteristics of the particulates in WCC is analyzed in this study by EEPS(engine exhaust particulate size spectrometer). The maximum number of PM is found to come out of WCC in sizes near 10nm when an HSDI diesel engine is operated under the conditions of high speed and medium to heavy load. When the temperature of the WCC exceeds $300^{\circ}C$, the number of PM smaller than 30 nm in diameter sharply increases upon passing through the WCC. Total mass of emitted PM gets reduced downstream of the WCC under low speed and light load conditions due to adsorption of PM onto the catalyst. Under conditions of high speed and medium to heavy load, the relatively large PM shrink or break into fine particles during oxidation process within the WCC, which results in more mass fraction of fine particles downstream of the WCC.

• 한국자동차공학회논문집
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• 제8권3호
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• pp.28-36
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• 2000

Spray characteristics of diesel fuel injection is one of the most important factors in diesel combustion and pollutant emissions especially in HSDI (High Speed Direct Injection) diesel engines where the interval between the onset of combustion and the evaporation of atomized fuel is relatively short, An investigation into various spray characteristics from different holes of VCO(Valve Covered Orifice) nozzles was performed and its results were compared to standard sac nozzle. The global characteristics of spray, including spray angle, spray tip penetration, and spray pattern were measured from the spray images which were frozen by an instantaneous photography with a spark light source. For better understanding of spray behavior, SMD of the fuel sprays from multi hole nozzles were measured with back light imaging while the sprays from the other holes are covered by a purpose-built nozzle cap. The investigation manifestly reveals the different spray patterns at the beginning of injection produced by VCO nozzles can be identified as three distinct types with their own macroscopic and microscopic characteristics, while macroscopic non-uniformity disappears at 0.9∼1.0ms from the start of injection.

• 대한간호학회지
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• 제34권1호
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• pp.141-149
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• 2004

Purpose: To identify the status of regular cervical cancer screening practices among middle-aged women, the associations between regular practice and research factors, and the predictive model and factors effecting such behavior was studied. Method: Two hundred women, aged 40 to 60, were selected by convenience in one urban area of Seoul. They were asked about their regular attendance for screening, knowledge of cancer and screening, health belief, health self-determination index and certain personal factors. Result: Approximately 54.5% of the women had periodic screening tests every 6 months to 2 years. Their knowledge of cervical cancer and health belief were at the medium level of each scale, but their health self-determination scores (HSDI) were low. Some influencing factors, and their cancer odds ratio were identified through univariate regression analysis. These variables were included in a predictive model, and this model proved to have enough fit and classification power (83.5%). In this model, the financial state, self-belief and self-determination scores were found to be significant. Conclusion: Middle-age women's intrinsic motivation for healthy behavior was found to be low in those who felt to be in a poor financial state, had higher perceived barriers, lower perceived benefits and a lower prevalence of undergoing regular screening test.

• 한국자동차공학회논문집
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• 제13권4호
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• pp.167-173
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• 2005

Thermal regeneration means burning-off and cleaning-up the particulate matters piled up in DPF(diesel particulate filter), and it requires both high temperature $(550\~600^{\circ}C)$ and appropriate concentration of oxygen at DPF entrance. However, it is not easy to satisfy such conditions because of the low temperature window of the HSDI(high speed direct injection) diesel engine(approximately $200\~350^{\circ}C$ at cycle). Therefore, this study is focused on the method to raise temperature using the trade-off relation between temperature, oxygen concentration, and the influence of many parameters of common rail injection system including post injection. After performing an optimal mapping of the common rail parameters for regeneration mode, the actual cleaning process during regeneration mode is investigated and evaluated the availability of the regeneration mode mapping through regenerating soot trapped in the DPF.

• 대한기계학회논문집B
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• 제26권9호
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• pp.1276-1283
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• 2002

Recently, HSDI (High Speed Direct Injection) diesel engine has been spotlighted as a next generation engine because it has a good potential for high thermal efficiency and fuel economy. This study was carried out to investigate the in-cylinder flow characteristics generated in a 4-valve small diesel cylinder head with a tangential and helical intake port. The flow characteristics such as coefficient of flow rate(Cf), swirl ratio (Rs), and mass flow rate (ms) were measured in the steady flow test rig using the impulse swirl meter and the analysis of in-cylinder flow field was conducted by experiment using the PIV and calculation using the commercial CFD code. As the results from steady flow test indicate, the mass flow rate of the cylinder head with a short distance between the two intake ports is increased over 13% than that of the other head. However, the non-dimensional swirl ratio is decreased approximately 15%. From in-cylinder flow characteristics obtained by PIV and CFD calculation, we found that the swirl center was eccentric from the cylinder center and the velocity distribution became uniform near the TDC. In addition, the results of the calculation are good agreement with the experimental results.

• 한방비만학회지
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• 제4권1호
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• pp.139-160
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• 2004

The obesity is detrimental to the health of people living in affluent societies. Individual differences in energy metabolism are caused primarily by single nucleotide polymorphisms(SNPs), some of which promote the development of obesity-related type 2 diabetes mellitus. Type 2 diabetes mellitus is a common multifactorial genetic syndrome, which is determined by several different genes and environmental factors. In this review, five major conclusions are reached: (1)To be clinically significant, SNPs must be relevant, prevalent, modifiable, and measurable. (2)Differences in SNPs may have been caused by famine, ultraviolet light, alcohol, climate, agricultural revolution. livestock, lactase persistence, and westernized lifestyle. (3)Candidate obesity genes of calorie intake restriction are SIM 1, MC3R, MC4R, AGRP, CART, CCK, CNTFR, DRD2, Ghrelin, 5-HT receptor, NPY, PON and those of energy metabolism are LEP, LEPR, UCP1, UCP2, UCP3, B2AR, B3AR, PGC-1, Androgen receptor and those of fat mobilization are AGT, ACE, ADA, APM1, Apolipoproteins, PPAR, FABP, FOXC2, GCGR, $11-{\beta}HSDI$, LDLR, Hormonal sensitive lipase, Perilipin, $TNF-{\alpha}$, $TNF-{\beta}$ (4)Candidate obesity genes in the eastern are NPY, LEP, LEPR, UCP1, UCP2, UCP3, B2AR, B3AR, ACE, APM1, PPAR, and FABP. (5)Candidate obesity genes in type 2 diabetes mellitus are MC3R, MC4R, B2AR, B3AR, ADA, APM1, PPAR, FABP, FOXC2, PC1, PC2, ABCC8, CAPN10, CYP19, CYP7, ENPP1, GCK, GYS1, IGF, IL-6, Insulin receptor, IRS, and LPL. The discovery of SNPs will lead to a greater understanding of the pathogenesis of obesity and to better diagnostics, treatment, and eventually prevention.