• Journal of Institute of Control, Robotics and Systems
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• v.10 no.12
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• pp.1305-1311
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• 2004

This study presents a mathematical model and a sliding mode observer of the injection system for common rail diesel engines. The injector model consists of three subsystems: the actuator subsystem, the mechanical subsystem, and the hydraulic subsystem. In the actuator subsystem, the constitutive relations of piezoelectricity are used to model the actuator made up of piezoelectric material. Based on the proposed model, the observer estimates the injection rate and injection timing, and can play a vital role of sensorless control of fuel injection in the near future. The sliding mode theory is applied to the observer design in order to overcome model uncertainties. The injector model and observer are evaluated through the injector experiments. The simulation results of the injector model are in good agreement with the experimental data. The sliding mode observer can effectively estimate the injection timing and the injection rate of the injector.

• The KSFM Journal of Fluid Machinery
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• v.10 no.2 s.41
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• pp.16-21
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• 2007

Potential advantages of using vapor injection in a two stage rotary compressor for a $CO_2$ heat pump water heater system were addressed in this paper by numerical simulation. Vapor separated from a flash tank in the middle of the expansion process can be used for injection into the second stage suction plenum of the compressor to improve the system performance. Vapor injection increases the intermediate pressure between the two stages, thus increasing the first stage compressor work and reducing that of the second stage. As a whole, however, the compressor input power increases due to injected mass flow rate for the second stage. Computer simulation showed that increment of the cooling capacity by vapor injection exceeded that of the compressor work, thus improving the system performance. COP improvement by vapor injection was calculated to be about 5-14% for normal operating conditions. With vapor injection, a maximum COP was found when the displacement volume of the second stage becomes 90-95% of that of the first stage of the compressor.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.29 no.11 s.242
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• pp.1445-1454
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• 2005

In order to minimize warping deformation which is an essential factor in the failure of injection molding parts, this study proposes an optimization design method fer determining design variables of injection molding parts. First, using a commercial package program for injection molding analysis, namely, Computer Aided Plastics Application(CAPA), we investigate the effects of parameters of injection molding process. Next, an optimum design process is established by interfacing CAPA to PQRSM embedded in EMD10S, a design framework developed by the conte. of innovative Design Optimization Technology(iDOT). PQRSM is a very efficient sequential approximate optimization algorithm. Optimum design results demonstrate the effectiveness of the design method suggested in this study by showing that the results of the optimum design is better than those of the initial design. It is believed that the proposed methodology can be applied to other injection molding design applications.

• The Korean Journal of Physiology and Pharmacology
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• v.20 no.6
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• pp.657-667
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• 2016

Critical limb ischemia (CLI) is one of the most severe forms of peripheral artery diseases, but current treatment strategies do not guarantee complete recovery of vascular blood flow or reduce the risk of mortality. Recently, human bone marrow derived mesenchymal stem cells (MSCs) have been reported to have a paracrine influence on angiogenesis in several ischemic diseases. However, little evidence is available regarding optimal cell doses and injection frequencies. Thus, the authors undertook this study to investigate the effects of cell dose and injection frequency on cell survival and paracrine effects. MSCs were injected at $10^6$ or $10^5$ per injection (high and low doses) either once (single injection) or once in two consecutive weeks (double injection) into ischemic legs. Mice were sacrificed 4 weeks after first injection. Angiogenic effects were confirmed in vitro and in vivo, and M2 macrophage infiltration into ischemic tissues and rates of limb salvage were documented. MSCs were found to induce angiogenesis through a paracrine effect in vitro, and were found to survive in ischemic muscle for up to 4 weeks dependent on cell dose and injection frequency. In addition, double high dose and low dose of MSC injections increased vessel formation, and decreased fibrosis volumes and apoptotic cell numbers, whereas a single high dose did not. Our results showed MSCs protect against ischemic injury in a paracrine manner, and suggest that increasing injection frequency is more important than MSC dosage for the treatment CLI.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.27 no.10
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• pp.1435-1441
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• 2003

Combustion characteristics on diesel-water emulsion are analyzed in high pressure injection for several variables such as water content, injection pressure and injection timing. As a fact of well-known, maximum combustion pressure was decreased and ignition delay was elongated in accordance with increasing of water content. But these characteristics were enhanced with increase of injection pressure to high pressure. It was shown that combustion of neat diesel in case of injecting with 600bar is similar to that of 20 % diesel-water emulsion was injected at 1200 bar.

• Transactions of the Korean Society of Automotive Engineers
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• v.20 no.1
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• pp.68-76
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• 2012

Recently, the important issues of gasoline engine are to reduce the fuel consumption and emission. Thus, many researchers are studying the technology to solve these problems. One approach of these issues is to achieve homogeneous charge combustion and stratified change combustion with various injection strategy. In this study, the combustion characteristics of DISI engine accrding to injection strategy were examined. The effect of injection timing on lean limit A/F were investigated using dual DISI single cylinder. The results show that the engine operation region of dual DISI type engine is larger than that of PFI and DISI type engine cases. Especially, late injection is very effective to extend the operation region more than any other injection timings. In addition, the results show that when the DISI injection ratio is increase, leam limit A/F is improved. It means that the dual injection system car meet with emission regulations and reduce the fuel consumption. Also, combustion pressure of dual injection system is much higher than PFI and DISI injection.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.25 no.7
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• pp.933-943
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• 2001

Using a semi-circled blunt body model, the geometrical effects of injection hole on the turbine blade leading edge film cooling are investigated. The film cooling characteristics of two shaped holes (laterally- and streamwise-diffused holes) and three cylindrical holes with different lateral injection angles, 30°, 45°, 60°, respectively, are compared with those of cylindrical hole with no lateral injection angle experimentally and numerically. Kidney vortices, which decrease the adiabatic film cooling effectiveness, appear on downstream of the cylindrical hole with no lateral injection angle. At downstream of the two shaped holes have better film cooling characteristics than the cylindrical one. Instead of kidney vortices, single vortex appears on downstream of injection holes with lateral injection angle. The adiabatic film cooling effectiveness is symmetrically distributed along the lateral direction downstream of the cylindrical hole with no lateral injection angle. But, at downstream of the cylindrical holes with lateral injection angle, the distribution of adiabatic film cooling effectiveness in the lateral direction shows asymmetric nature and high adiabatic film cooling effectiveness regions are more widely distributed than those of the cylindrical hole with no lateral injection angle. As the blowing ratio increases, also, the effects of hole shapes and injection angles increase.

• Journal of Pharmacopuncture
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• v.12 no.3
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• pp.31-40
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• 2009

Objective : This study was to investigate the effects of distilled Cervi Pantotrichum Cornu Pharmacopuncture and Zizyphi Spinosi Semen Pharmacopuncture on autonomic nervous system with Heart Rate Variability(HRV). Purpose of the trial was to observe what influence distilled Cervi Pantotrichum Cornu Pharmacopuncture and Zizyphi Spinosi Semen Pharmacopuncture have on the autonomic nervous system. Methods : 60 healthy male volunteers were divided into three groups which consist of two experimental groups such as Cervi Pantotrichum Cornu Pharmacopuncture and Zizyphi Spinosi Semen Pharmacopuncture, and a control group. Study design was a randomized, placebo-controlled, double-blind clinical trial. 20 subjects in experimental group were injected distilled Cervi Pantotrichum Cornu Pharmacopuncture at $GB_{21}$(Kyonjong), 20 subjects in other experimental group were injected distilled Zizyphi Spinosi Semen Pharmacopuncture and 20 subjects in control group were injected Normal Saline at $GB_{21}$(Kyonjong). One volunteer of each groups were excluded from analysis because of error during measuring HRV. At the end of the study 57 volunteers completed HRV analysis. HRV was measured by QECG-3:LXC3203(LAXTHA Inc. Korea) at P0, P1, P2, P3, P4, P5 and P6 and its time-course dependent change in each group was analyzed using paired t-test, and the difference of HRV fluctuation among two experimental group and a control was evaluated by one way ANOVA(p<0.05). Results : A. Time Domain Analysis 1. Analysis of Mean HRV, SDNN and Complexity After injection of distilled Cervi Pantotrichum Cornu Pharmacopuncture, Mean HRV was significantly decreased only at 20 minutes after injection. SDNN was significantly increased from 15 minute after injection. Complexity was significantly decreased only at 15 minute after injection. After injection of distilled Zizyphi Spinosi Semen Pharmacopuncture, Complexity was significantly decreased at 10, 15 and 30 minutes after injection. 2. Analysis of HRV index, pNN50 After injection of distilled Cervi Pantotrichum Cornu Pharmacopuncture, pNN50 was significantly decreased at 15, 20 and 25 minutes after injection. Compared with Normal Saline injection, distilled Cervi Pantotrichum Cornu Pharmacopuncture and Zizyphi Spinosi Semen Pharmacopuncture showed significant difference on HRV index and pNN50 at 5 minutes after injection. B. Frequency Domain Analysis 1. Analysis of Ln(TP), Ln(VLF) After injection of distilled Cervi Pantotrichum Cornu Pharmacopuncture, Ln(TP) was significantly increased at 15 and 30 minutes after injection. Ln(VLF) was significantly increased at 10, 15 and 30 minutes after injection. After injection of distilled Zizyphi Spinosi Semen Pharmacopuncture, Ln(VLF) was significantly increased only at 30 minutes after injection. Compared with Normal Saline injection, distilled Cervi Pantotrichum Cornu Pharmacopuncture showed significant difference on Ln(TP) after 5 minutes of injection. Conclusions : Our results suggest that Cervi Pantotrichum Cornu Pharmacopuncture and Zizyphi Spinosi Semen Pharmacopuncture in healthy adult man tend to activate the autonomic nervous system and sympathetic nervous system compared to Normal Saline within normal range.

• Journal of the Korea Institute of Building Construction
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• v.6 no.2 s.20
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• pp.91-98
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• 2006

The purpose of this study is to investigate the problem of crack repair materials and methods in existing concrete structure and to propose the effective injection method on crack repair by packer type. The result of this study is as follows. It is investigated that the crack width in the inner matrix of concrete structure is decreased about 30-40% than that in the sulfate of the concrete structure. Also it is showed that the possibility which could be monolithic with injection part became higher if the injection part if installed near to surface of concrete on the punching method to vertical direction against crack area. The injection of repair material can be poured smoothly under about $10N/mm^2$ pressure on the condition that cracks are monolithic with injection part without dust by drill. The effective method to pour the injection repair material is the punching method by coredrill but several research to minimize injection pressure should be continually.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.22 no.8
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• pp.1101-1110
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• 1998

Computational investigation was conducted to examine the performance of a high pressure common-rail fuel injection system which is used to power a passenger car direct injection (Dl) diesel engine. The pipe flows were modeled by one dimensional wave equation and solved by implicit FDM Each volume of injector was considered as chambers with orifice nozzle in connections. These simulation results were compared with the experimental data of Ganser Hydromag. The comparison of needle life and rate of injection between simulation data and experimental data showed quite a good agreement Different shape of injection rate can be made by adjusting the size of inlet orifice and exit orifice in the piston chamber The pilot injection was accomplished by adjusting command signal.