• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2004.11a
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• pp.857-861
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• 2004

An active method that improves low frequency characteristics of a reverberation chamber has been proposed. Spatial uniformity of sound pressure at low frequency has been increased by applying active noise control system. The system acts as frequency selective damping materials, which decreases resonance at low frequency and leave high frequency sound field as it is. Linearity of the chamber, which is essential for sound power measurement in the chamber, is guaranteed since fixed control logic has been adopted. Simple application and tests have been done in a small sized rectangular reverberation chamber which has 400Hz cutoff, Loud speakers were used to simulate a noise source and to construct an active noise control system. The spatial distribution of a sound field at 250Hz, 315Hz and 400Hz bands has been measured before and after control. The standard deviation of sound field has been decreased from 3.4dB to 2.5dB. The results show the possibility of active control system as a sound diffuser.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.7 no.3
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• pp.285-290
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• 2006

In a Vehicle, Safety is the most important factor for drivers. It is well known that tire pressure lower than normal reduces the safety of the vehicle. In a consideration of active safety, tire pressure monitoring system is absolutely required. Tire pressure monitoring using in-tire pressure sensors with an RE data link have proven to be best approach to measuring tire pressure over the widest range of operating conditions. In this paper, we describe the parameters of TPMS, the characteristic of tire pressure and temperature compensation. These are the main factors to design the decision logic. We will show the guidelines for TPMS logic development considering environment variables and vehicle conditions.

• The Bulletin of The Korean Astronomical Society
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• v.44 no.2
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• pp.39.3-39.3
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• 2019

Ram pressure stripping due to the intracluster medium (ICM) is an important environmental process, which causes star formation quenching by effectively removing cold interstellar gas from galaxies in dense environments. The evidence of diffuse atomic gas stripping has been reported in several HI imaging studies. However, it is still under debate whether molecular gas (i.e., a more direct ingredient for star formation) can be also affected and/or stripped by ram pressure. The goal of this thesis is to understand the impact of ram pressure on the molecular gas content of cluster galaxies and hence star formation activity. To achieve this, we conducted a series of detailed studies on the molecular gas properties of three Virgo spiral galaxies with clear signs of active HI gas stripping (NGC 4330, NGC 4402, and NGC 4522) based on high-resolution CO data obtained from the Submillimeter Array (SMA) and Atacama Large Millimeter/submillimeter Array (ALMA). As a result, we find the evidence that the molecular gas disk also gets affected by ram pressure in similar ways as HI even well inside of the stellar disk. In addition, we detected extraplanar 13CO clumps in one of the sample, which is the first case ever reported in ram pressure stripped galaxies. By analyzing multi-wavelength data (e.g., Hα, UV, HI, and CO), we discuss detailed processes of how ram pressure affects star formation activities and hence evolution of cluster galaxies. We also discuss the origin of extraplanar 13CO, and how ram pressure can potentially contribute to the chemical evolution of the ICM.

• Archives of Pharmacal Research
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• v.15 no.1
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• pp.104-108
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• 1992

2, 3-Diphenyl-6-formyl-5-methoxyindole reacts with ethyl cyano acetate to yield the arylidene derivative which forms with urea and thiourea the corresponding pyrimidine derivatives. The arylidene derivatives react with hydrazines and with active methylenes to form the respective pyrazole derivatives and the $\alpha, \;\beta$-disubstituted acrylonitriles. Seven new compounds were tested for their effects on the arterial blood pressure of rats and analgesic activity.

• KOREAN JOURNAL OF PACKAGING SCIENCE & TECHNOLOGY
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• v.6 no.1
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• pp.31-36
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• 2000

180g of fermented soy paste and 150g of red pepper paste were packaged in glass jars of 232 mL with different conditions of active packaging and then stored at $13^{\circ}C$ for about 170 and 128 days, respectively. During the storage, package atmosphere, surface color, pH, acidity and microbial flora were monitored to see the effect of packaging conditions. Test packaging conditions include package equipped with $Ca(OH)_2\;as\;CO_2$ absorber, package with pinhole and closed control one. Closed control packages of soypaste and red pepper paste showed the increased $CO_2$ partial pressure, the decreased $O_2$ partial pressure and the constant $N_2$ partial pressure to produce high pressure buildup with storage. The paste packages with $Ca(OH)_2$ maintained relatively low $CO_2$ partial pressure and thus the package pressure close to normal atmospheric pressure for initial storage period of 70 days. The packages with air pinhole channel had the partial pressures of $O_2\;and\;N_2$ decreased with storage time, while $CO_2$ partial pressure first increased to a maximum and then slowly decreased thereafter Without any pressure increase the packages with pinhole gave the lowest quality changes possibly due to the effect of package atmosphere, but it had problem of mold contamination and growth for soy paste after 120 days. There were no difference in microbial flora between the packages after about 70 day storage.

• Journal of the Korean Geotechnical Society
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• v.33 no.11
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• pp.59-72
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• 2017

In this study, the calculation method of the active earth pressure acting on the imaginary vertical plane at the end of the heel of the wall is proposed. For cantilever retaining wall, a change of shear zone behind the wall affects the earth pressure in the vertical plane at the end of heel of the wall depending on wall friction and angle of ground slope. It is very complicated to calculate the earth pressure by a limit equilibrium method (LEM) which considers angles of failure planes varying according to the heel length of the wall. So, the limit analysis method (LAM) is used for calculation of earth pressure in this study. Using the LAM, the earth pressures considering the actual slope angles of failure plane are calculated accurately, and then horizontal and vertical earth pressures are obtained from them respectively. This study results show that by decreasing the relative length of the heel, the slope angle of inward failure plane becomes larger than theoretical slope angle but the slope angle of outward failure plane does not change. And also the friction angle on the vertical plane at the end of the heel of the wall is between the ground slope angle and the wall friction angle, thereafter the active earth pressure decreases. Finally, the Coulomb earth pressure can be easily calculated from the relationship between friction angle (the ratio of vertical earth pressure to horizontal earth pressure) and relative length of the heel (the ratio of heel length to wall height).

• International Journal of Automotive Technology
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• v.3 no.1
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• pp.27-32
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• 2002

Semi-active suspension systems are greatly expected to be in the mainstream of future controlled suspensions fur passenger cars. In this study, a continuous variable damper for a passenger car suspension is developed. It is controlled actively and exhibits high performance with light weight, low cost, and low energy consumption. To get fast response of the damper, reverse damping mechanism is adapted, and to get small pressure change rate after blow-off, a pilot controlled proportional valve is designed and analyzed. The reverse continuous variable damper is designed as a HS-SH damper which offers good body control with reduced transferred input force from tire, compared with any other type of suspension system. The damper structure is designed, so that rebound and compression damping force can be tuned independently, of which variable valve is placed externally. The rate of pressure change with respect to the flow rate after blow-offbecomes smooth when the fixed orifice size increases. Damping forces are measured with the change of the solenoid current at the different piston velocities to confirm the maximum hysteresis of 20N, linearity, and variance of damping farce. The damping farce variance is wide and continuous, and is controlled by the spoof opening, of which scheme is usually adapted in proportional valves. The reverse continuous variable damper developed in this study is expected to be utilized in the semi-active suspension systems in passenger cars after its performance and simplicity of the design is confirmed through real car test.

• Transactions of the Korean Society of Automotive Engineers
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• v.21 no.2
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• pp.26-36
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• 2013

Purpose of this study is to develop virtual components and environment for developing a controller of an Active Air Suspension System in laboratory that slough off existing development environment using real vehicle test. This paper presents an air spring modeling and analysis of air suspension system for a commercial vehicle. Preferentially, It was performed vehicle test for pneumatic system and an air spring for characteristic analysis of system. Each component of an air spring suspension system was developed through emulations and modeling of system for pressure and height sensors in the basis on test results in SILS environment. Non-linear characteristics of air spring are accounted for using the measured data. Also, pressure and volume relations for vehicle hight control is considered. After performance verification of virtual model was performed, we developed virtual environment based on HILS for an Active Air Suspension System. We studied estimation and verification technology for control algorithm that developed.

• Journal of Mechanical Science and Technology
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• v.20 no.4
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• pp.554-560
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• 2006

This paper describes the demonstration of successful fabrication and initial characterization of micromachined pressure sensors and micromachined jets (microjets) fabricated for use in macro flow control and other applications. In this work, the microfabrication technology was investigated to create a micromachined fluidic control system with a goal of application in practical fluids problems, such as UAV (Unmanned Aerial Vehicle)-scale aerodynamic control. Approaches of this work include: (1) the development of suitable micromachined synthetic jets (microjets) as actuators, which obviate the need to physically extend micromachined structures into an external flow; and (2) a non-silicon alternative micromachining fabrication technology based on metallic substrates and lamination (in addition to traditional MEMS technologies) which will allow the realization of larger scale, more robust structures and larger array active areas for fluidic systems. As an initial study, an array of MEMS pressure sensors and an array of MEMS modulators for orifice-based control of microjets have been fabricated, and characterized. Both pressure sensors and modulators have been built using stainless steel as a substrate and a combination of lamination and traditional micromachining processes as fabrication technologies.

• Journal of the korean Society of Automotive Engineers
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• v.7 no.2
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• pp.45-54
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• 1985

Recently, the problem of exhaust gas pollution is increasingly being aggravated by the active use of the Diesel engine. For the fuel-injection system which affects the composition of exhaust gas from the Bosch type single-hole nozzle in the Diesel engine, a mathematical model was set up to study pressure variations in the high pressure pipe, the injection rate, and the needle lift. The fundamental equations of the mathematical model have been solved by the Newton Raphson Method applying the Finite Diffrence Method. The effective stroke of the injection pump plunger due to a change in engine rpm was calculated by the measurement of Control Rack, Pinion, and Plunger sizes and by the use of Characteristic Curve of Governor. The computed results for the pressure variations in the high pressure pipe and needle lift at 800 rpm and 1000 rpm are in good agreement with experimental ones in general. By a developed program, the effects of other various parameters will by calculated for the performance of the fuel-injection system.