• Transactions of the Korean Society of Mechanical Engineers A
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• v.24 no.5 s.176
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• pp.1305-1313
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• 2000

In a co-rotating scroll compressor, both scrolls rotate on their fixed axes contrary to the conventional orbiting type scroll machine. This implies fixed locations and directions of the gas pressure force and sealing force. Because the tilting moment is mainly caused by interplay between the resultant force of above forces and bearing reaction force, the variation during one cycle is relatively small. Under real operation, this moment is balanced by the restoring moment created by the reaction between the baseplate and thrust bearing or between the scroll tip and baseplate. If these reactions become too large, greater torque is required due to increased friction in addition to the wear of mating parts. Consequently, appropriate study and minimization of tilting moment is important in the design of scroll machines. In this study, taking into account of the small variation of tilting moment during one cycle, we minimize the moment and thrust bearing reaction force by a properly designed back pressure chamber. As a result, for both the driving and driven scrolls, the tilting moment and the reaction force of thrust bearing can be minimized. And the stability is improved for all cases.

• Korean Journal of Materials Research
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• v.14 no.5
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• pp.368-373
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• 2004

To improve the conventional cathode-supported tubular solid oxide fuel cell (SOFC) from the viewpoint of low cell power density, expensive fabrication process and high operation temperature, the anode-supported tubular solid oxide fuel cell was investigated. The anode tube of Ni-8mol% $Y_2$O$_3$-stabilized $ZrO_2$ (8YSZ) was manufactured by extrusion process, and, the electrolyte of 8YSZ and the multi-layered cathode of $LaSrMnO_3$(LSM)ILSM-YSZ composite/$LaSrCoFeO_3$ were coated on the surface of the anode tube by slurry dip coating process, subsequently. Their cell performances were examined under gases of humidified hydrogen with 3% water and air. In the thermal cycle condition of heating and cooling rates with $3.33^{\circ}C$/min, the anode-supported tubular cell showed an excellent resistance as compared with the electrolyte-supported planar cell. The optimum hydrogen flow rate was evaluated and the air preheating increased the cell performance due to the increased gas temperature inside the cell. In long-term stability test, the single cell indicated a stable performance of 300 mA/$\textrm{cm}^2$ at 0.85 V for 255 hr.

• Animal cells and systems
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• v.16 no.3
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• pp.173-182
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• 2012

The p53 protein plays a pivotal role in tumor suppression. The cellular level of p53 is normally kept low by proteasome-mediated degradation, allowing cell cycle progression and cell proliferation. Under stress conditions, such as DNA damage, p53 is stabilized and activated through various post-translational modifications of itself as well as of its regulatory proteins for induction of the downstream genes responsible for cell cycle arrest, DNA repair, and apoptosis. Therefore, the level of p53 should be tightly regulated for normal cell growth and for prevention of the accumulation of mutations in DNA under stress conditions, which otherwise would lead to tumorigenesis. Since the discovery of Mdm2, a critical ubiquitin E3 ligase that destabilizes p53 in mammalian cells, nearly 20 different E3 ligases have been identified and shown to function in the control of stability, nuclear export, translocation to chromatin or nuclear foci, and oligomerization of p53. So far, a large number of excellent reviews have been published on the control of p53 function in various aspects. Therefore, this review will focus only on mammalian ubiquitin E3 ligases that mediate proteasome-dependent degradation of p53.

• Journal of Energy Engineering
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• v.18 no.3
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• pp.156-162
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• 2009

Cylinder-pressure based combustion analysis provides a mechanism through which a combustion researcher can understand the combustion process. This paper was to identify the most significant sources of cycle-to-cycle combustion variability in a spark ignition engine at idle. To analyse the cyclic variation in the test engine, the burn parameters are determined on a cycle-to-cycle basis through analysis of the engine pressure data. The burn rate analysis program was used in the analysis of the data. Burn parameters were used to determine the variations in the input parameter-i.e., fuel, air, residual mass, and so on.

• Structural Engineering and Mechanics
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• v.40 no.6
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• pp.847-866
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• 2011

The objective of this study was to experimentally investigate the bond-related tension stiffening behavior of flexural reinforced concrete (RC) beams made with lightweight aggregate concrete (LWAC) under various high-cycle fatigue loading conditions. Based on strain measurements of tensile steel in the RC beams, fatigue-induced degradation of tension stiffening effects was evaluated and was, compared to reinforced normal weight concrete (NWC) beams with equal concrete compressive strengths (40 MPa). According to applied load-mean steel strain relationships, the mean steel strain that developed under loading cycles was divided into elastic and plastic strain components. The experimental results showed that, in the high-cycle fatigue regime, the tension stiffening behavior of LWAC beams was different from that of NWC beams; LWAC beams had a lesser reduction in tension stiffening due to a better bond between steel and concrete. This was reflected in the stability of the elastic mean steel strains and in the higher degree of local plasticity that developed at the primary flexural cracks.

• Food Science and Biotechnology
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• v.17 no.4
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• pp.755-760
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• 2008

The aim of this study was to produce resistant starch preparations from acid-modified com starches prepared at various hydrolysis levels (0.5-4.0 hr). Effect of autoclaving cycles on resistant starch (RS) formation was investigated. Molecular weight distribution, pasting and functional properties of acid-modified com starches were determined. For RS formation native and acid-modified starch samples were gelatinized and autoclaved (1 or 2 cycles). While native and acid-modified starches did not contain any RS, the levels increased to 9.0-13.5% as a result of storage at $95^{\circ}C$ after first autoclaving cycle. Second autoclaving cycle together with storage at $95^{\circ}C$ brought final RS contents of the samples incubated at 4 and $95^{\circ}C$ after the first cycle to comparable level. As acid modification level increased, the amount of high molecular weight fractions decreased, resulting in significant decreases in viscosities (p<0.05). The samples produced in this study had low emulsion stability and capacity values.

• Korean Journal of Food Science and Technology
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• v.30 no.1
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• pp.132-138
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• 1998

This study was conducted to evaluate the storage stability of danmooji(salted radish) treated with high hydrostatic pressure $(300{\sim}686\;MPa)\;and\;heat\;(55^{\circ}C)$. Danmooji pressurized at 500 MPa and 686 MPa for 5 min showed $4{\sim}6log-cycle$ reductions in total microorganism, while danmooji heated at $55^{\circ}C\;for\;2\;hr\;showed\;3{\sim}5log-cycle$ reductions. However, danmooji pressurized at 300 MPa for 5 min showed a 2 log-cycle reduction, indicating that pressurization at lower than 300 MPa is insufficient for sterilization. After pressurized at 300 MPa, 500 MPa and 686 MPa for 5 min, pectinesterase (PE) activity of danmooji was increased by approximately 35%, 76% and 64%, respectively; and polygalacturonase (PG) activity of danmooji was increased by 109%. 163% and 120%, respectively. After heated at $55^{\circ}C$ for 2 hr, PE and PG activities of danmooji were increased by 18% and 200%, respectively. This indicates that PE in danmooji was more activated bypressure than heat, while PG was mostly activated by heat. Pressurized and heat-treated danmooji had higher hardness than control and maintained its hardness during storage at $30^{\circ}C$.

• Journal of Power Electronics
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• v.12 no.1
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• pp.164-171
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• 2012

Variable step size maximum power point trackers (MPPTs) are widely used in photovoltaic (PV) systems to extract the peak array power which depends on solar irradiation and array temperature. One essential factor which judges system dynamics and steady state performances is the scaling factor (N), which is used to update the controlling equation in the tracking algorithm to determine a new duty cycle. This paper proposes a novel stability study of variable step size incremental resistance maximum power point tracking (INR MPPT). The main contribution of this analysis appears when developing the overall small signal model of the PV system. Therefore, by using linear control theory, the boundary value of the scaling factor can be determined. The theoretical analysis and the design principle of the proposed stability analysis have been validated using MATLAB simulations, and experimentally using a fixed point digital signal processor (TMS320F2808).

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.06a
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• pp.1605-1608
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• 2005

This study was carried out to analyze the effect of machinery house location on the stability of high efficiency gantry crane which can improve the productivity of the container transportation wok by reducing cycle time. The wind load was evaluated according to 'Load Criteria of Building Structures' enacted by the ministry of construction & transportation. The uplift forces of high efficiency gantry crane under this wind load were calculated by analyzing reaction forces at each supporting point. And variation of reaction forces at each supporting point was analyzed according to machinery house location.

• 한국HCI학회:학술대회논문집
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• 2009.02a
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• pp.2068-2071
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• 2009

This paper presents a multiple degree-of-freedom (dof) energy bounding approach (EBA) to enhance directional transparency while guaranteeing stability for multiple-dof haptic interaction. It was observed that the passivity condition for multiple ports may lead to some oscillatory limit cycle behaviors in some coordinate directions even though the total sum of energy flow-in is positive, meaning that the system is passive. The passivity condition, therefore, needs to be applied to each coordinate in order to avoid oscillatory behavior by keeping each energy flow-in always positive. For guaranteeing passivity, which in turn, stability in each coordinates, the EBA is applied. For multiple-dof haptic interaction, however, the EBA in each coordinate may distort the direction of the force vector to be rendered since the EBA may cut down the magnitude of the force and torque vectors to be rendered in order to ensure the passivity. For avoiding this problem, a simple projection method is presented. The validity of the proposed algorithm is shown by several experiments.