• Journal of the Korean Solar Energy Society
• /
• v.23 no.1
• /
• pp.1-8
• /
• 2003

Various efforts to combine new high-tech materials with solar system have been progressed nowadays in order to improve the performance of the existing passive solar system. TIM(Transparent Insulation Material) replacing the conventional outer building envelope glazing as well as the wall is good example for this trend. TI integrated wall is a thermal mass wall with a special shaped TIM instead of using typical envelope materials The tested TIM type is a small(diameter 4mm and thickness 50mm) capillary tube of Okalux model and cement brick(density 1500kg/m3). The purpose of this study was to analyze the thermal performance through the actual measurements performed in a test cell. This study was carried out to justify the following issues. 1) the impact of Tl-wall over the temperature variations 2) the impact of mass wall surface absorptance over the transient thermal behavior and 3) the impact of thermal mass wall thickness over the temperature variations. Finally, as results indicated that the peak time of room temperature was shifted about one hour early when absorptance of thermal mass wall changed from 60% to 95% for the 190mm thickness thermal mass wall test case. the temperature difference of both surfaces of thermal mass wall surface showed about $23^{\circ}C$ during a day of March for the 380mm thickness thermal mass wall case. However, the thermal mass wall was over-heated by outside temperature and solar radiation in a day of May the temperature difference of both surfaces of thermal mass wall surface was indicated $10^{\circ}C$ and inside temperature was observed more than average 22C.

• The Bulletin of The Korean Astronomical Society
• /
• v.35 no.1
• /
• pp.56.2-56.2
• /
• 2010

M87, a cD galaxy in the Virgo cluster, has 3-10 times larger enclosed mass than the Milky Way at any given galactocentric radius. Thus the globular cluster (GC) system in M87 is expected to have undergone a more significant dynamical evolution than that of the Milky Way if it had started from the same initial mass function (MF) and radial distribution (RD) as the Milky Way. The evolution of MF and RD of the M87 GC system has been calculated using an advanced, realistic Fokker-Planck (FP) model that considers dynamical friction, disk/bulge shocks, and eccentric cluster orbits. We perform hundreds of FP calculations with different initial cluster conditions, and then search a wide parameter space for the best-fit initial GC MF and RD that evolves into the observed present-day GC MF and RD. We also find best-fit initial MFs and RDs for blue and red GC groups, separately.

• International Journal of Control, Automation, and Systems
• /
• v.2 no.2
• /
• pp.144-155
• /
• 2004

This paper addresses the issue of position control of a chain of multiple mass-spring-damper (CMMSD) units which can be found in many physical systems. The dynamic model of a CMMSD system with any degrees of freedom is expressed in a closed-form for the convenience of the controller design. Backstepping and model reference adaptive control (MRAC) approaches are then used to develop two adaptive output feedback controllers to control the position of a CMMSD system. The proposed controllers rely on the measurements of the input (force) and the output (position of the mass unit at the end of the chain) of the system without the knowledge of its parameters and internal states. Simulations are used to verify the effectiveness of the controllers

• International Journal of Aerospace System Engineering
• /
• v.2 no.1
• /
• pp.6-11
• /
• 2015

An active flow control technique using blowing and distributed suction on low Reynolds airfoil is investigated. Simultaneous blowing and distributed suction can recirculate the jet flow mass, and reduce the penalty to propulsion system due to avoiding dumping the jet mass flow. Energy is injected into main flow by blowing on the suction surface, and the low energy boundary flow mass is removed by distributed suction, thus the flow separation can be successfully suppressed. Aerodynamic lift to drag ratio is improved significantly using the flow control technique, and the energy consumption is quite low.

• Journal of Applied Reliability
• /
• v.18 no.3
• /
• pp.229-239
• /
• 2018

Purpose: There is a difficulty in Environmental Stress Screening (ESS) test design for weapon system's electrical/electronic components/products in small and medium-sized enterprises. To overcome this difficulty, I propose an easy ESS test design approach algorithm that is optimized with only one environment tolerance design information parameter (${\Delta}T$). Methods: To propose the mass production weapon system ESS test design for cost-effective optimization, I define an optimum cost-effective mathematical model ESS test algorithm model based on modified MIL-HDBK-344, MIL-HDBK-2164 and DTIC Technical Report 2477. Results: I clearly confirmed and obtained the quantitative data of ESS effectiveness and cost optimization along our ESS test design algorithm through the practical case. I will expect that proposed ESS test method is used for ESS process improvement activity and cost cutting of mass production weapon system manufacturing cost in small and medium-sized enterprises. Conclusion: In order to compare the effectiveness of the proposed algorithm, I compared the effectiveness of the existing ESS test and the proposed algorithm ESS test based on the existing weapon system circuit card assembly for signal processing. As a result of the comparison, it was confirmed that the test time was reduced from 573.0 minutes to 517.2minutes (9.74% less than existing test time).

• Journal of Astronomy and Space Sciences
• /
• v.24 no.1
• /
• pp.31-38
• /
• 2007

We have investigated the evolutionary status of 85 Peg within the framework of standard evolutionary theory. 85 Peg has been known to be a visual and spectroscopic binary system in the solar neighborhood. In spite of the accurate information of the total mass (${\sim}1.5M_{\odot}$) and the distance (${\sim}12pc$) from the HIPPARCOS parallax, it has been undetermined an individual mass, therefore the evolved status of the system. Moreover, the coupled uncertainties of chemical composition and age, make matters worse in predicting an evolutionary status of the system. Nevertheless, we computed the various possible models for 85 Peg, and then calibrated stellar parameters by adjusting to the recent observational data. Our modelling computation has included recently updated input physics and stellar theory such as opacity, equation of state, and chemical diffusion. Through a statistical assessment, we have derived a confident parameter set as the best solution which minimized $X^{2}$ within the observational error domain. Most of all, we found that 85 Peg is not a binary system but a triple system with an unseen companion 85 Peg $B_{b}\;{\sim}0.16M_{\odot}$. The aim of the present paper is (1) to provide a complete modelling of the stellar system based on the evolutionary theory, and (2) to constrain the physical dimensions such as mass, metallicity and age.

• 제어로봇시스템학회:학술대회논문집
• /
• 2003.10a
• /
• pp.307-311
• /
• 2003

2-mass system is generally used as controller of the variable-speed to transfer electromotion power to mechanical load such as industrial robot, driving parts of electric vehicle, rolling machine system of steel plant and driving parts of elevator. In this case, PI controller is often used as a velocity controller because of simplicity of system. But PI control algorithm is not enough for obtaining the control characteristics required for this system. To solve this problem, 2-mass system based on the PID controller derives the optimum PID parameters by pole assignment and estimation of the ITAE performance index. In this case, the system have tenacious properties about disturbance, but it causes extreme overshoot and vibration because of rapidly output of controller in early transient response about desired value. And if speed control system is applied by 2-DOF parameter ${\alpha}$, a temporary value, we must induce most suitable parameter by complicate pole assignment and estimation of the ITAE performance index whenever ${\alpha}$ changes. In this paper, to solve this problem we suggest control algorithm to followed exactly value of ${\alpha}$ as 2-DOF parameter by using fuzzy algorithm . So, intelligence algorithm modeled by human knowledge, experience, teachability and judgment follow exact ${\alpha}$ value and it can compose the efficient 2-DOF PID controller to improve following performance, overshoot decrease.

• Transactions of the Korean Society of Mechanical Engineers
• /
• v.17 no.2
• /
• pp.248-256
• /
• 1993

This paper deriver the generalized mass to find dynamic characteristics and its derivatives of a continous system. And a new sensitivity analysis method is presented by using the amount of change of generalized mass and vibrational mode caused by the variation of lumped and distributed mass. In this paper, to get or detect appropriate results, cantilever beam and stepped beam are used. Deviations of sensitivity coefficient, natual frequency, vibrational mode and transfer function are calculated as result, and compared with the theoretical exact values.

• Mass Spectrometry Letters
• /
• v.3 no.4
• /
• pp.108-111
• /
• 2012

An experimental study on the nascent product of the OH heterogeneous reaction with NaCl was performed under dry and wet conditions using a bead-filled flow tube system coupled to a high-pressure chemical ionization mass spectrometer. The ozone concentration in the flow tube for the atomic hydrogen removal was varied in order to control the conversion reaction of molecular chlorine into HCl for the identification of the nascent product. The mass spectrometric observation was that the $O_3$ introduction reduced the concentration HCl, while it increased the concentration of $Cl_2$ and ClO. Based on the experimental results, we suggest that the nascent product of the titled reaction is gaseous $Cl_2$, which is followed by fast conversion into HCl in presence of H. No significant difference in the concentration profile between under dry and wet (RH = 2%) conditions was observed.

• Tunnel and Underground Space
• /
• v.6 no.2
• /
• pp.131-143
• /
• 1996

In-situ survey and laboratory rock test were carried out for rating rock mass around the tunnel that some failures had been occurred in Danyang limestone quarry. For rating rock mass, several methods such as RMR, Q-system, rock strength etc. were applied. The stability analysis on tunnel was evaluated by numerical method FLAC. And The block theory using streographic projection was also applied for stability analysis. The 3-4 major discontinuity sets are distributed in rock mass around tunnel.