• Transactions of the Korean Society of Mechanical Engineers A
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• v.26 no.4
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• pp.754-763
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• 2002

Direct drive servovalve(DDV) is a kind of one-stage valve since the rotary motion of DC motor is directly transferred to the linear motion of valve spool through the link. Since the structure of DDV is simple, it is less expensive, more reliable and offers reduced internal leakage and reduced sensitivity to fluid contamination. However, the flow force effect on the spool motion is significant such that it induces large steady-state error in a step response. If the proportional control gain is increased to reduce the steady-state error, the system becomes unstable. In order to satisfy the system design requirements, the classical controller is designed using the analytical Bode method.

• Journal of ILASS-Korea
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• v.24 no.2
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• pp.66-72
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• 2019

Diesel vehicles suffer from poor starting and running problems at cold temperatures. Diesel vehicles have the characteristic that CO and PM are reduced or similarly discharged when going from low temperature to high temperature. In this study, a bypass type piezo injector for electronic control based common rail injection system was used. Numerical analysis using injector drive analysis model was performed to analyze injector drive and internal fuel flow characteristics according to fuel temperature change. The results show that the rate of density change due to the fuel temperature is proportional, and that the effect of the kinematic viscosity is relatively large between $-20^{\circ}C$ and $0^{\circ}C$. Comparing the results of temperature condition at $0^{\circ}C$ and $20^{\circ}C$, it is considered that the viscosity is more correlated with the needle displacement than the pressure chamber of the delivery chamber.

• Journal of Digestive Cancer Research
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• v.11 no.2
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• pp.108-113
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• 2023

Dyspnea is a common symptom among patients with gastrointestinal cancer, and a comprehensive evaluation of their respiratory function is essential. Self-reporting aids in the assessment of the degree of dyspnea, while objective examination methods are performed to identify the potential underlying causes when subjective symptoms are present. Standard treatment protocols should be followed for potentially reversible and common causes of dyspnea, such as pleural effusion, pneumonia, airway obstruction, anemia, asthma, exacerbation of chronic obstructive pulmonary disease, pulmonary thromboembolism, or drug-induced interstitial lung disease. Careful and close monitoring is required due to the high frequency of pulmonary thromboembolism and the risk of cardiovascular accidents, drug-induced interstitial lung disease, or other complications from some anticancer drugs. In case of hypoxemia with an oxygen saturation of 90% or less, palliative treatment should comprise standard oxygen therapy such as nasal cannula, mask, or high-flow nasal cannula. If non-pharmacological oxygen therapy is not effective, pain control through systemic narcotic analgesics and anti-anxiety therapy with benzodiazepines may be helpful.

• 제어로봇시스템학회:학술대회논문집
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• 2003.10a
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• pp.1480-1484
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• 2003

This paper presents the design and development of network for housing estate security system. The system can cover up to 961 houses which can be up to 1,200 meters long transfer rate of 9,600 bps. This system uses checking and warning the abnormal situation. More over this system has ability to control switch on/off the electrical equipment in the house via AC line control system. The system consists of 4 parts. The first part is a security system of each house using MCS-51 microcontroller as a central processing unit scan 32 sensors and control 8 appliances and send alarm. The MCS-51 microcontroller received control signal via telephone used DTMF circuit. The second part is distributed two levels master/slave network implementing after RS-485 serial communication standard. The protocol its base on the OSI (Open Systems Interconnection) 7 layers protocol model design focus on speed, reliability and security of data that is transferred. The network security using encrypt by DES algorithm, message sequence, time stamp checking and authentication system when user to access and when connect new device to this system. Flow control in system is Poll/Select and Stop-and-Wait method. The third part is central server that using microcomputer which its main function are storing event data into database and can check history event. The final part is internet system which users can access their own homes via the Internet. This web service is based on a combination of SOAP, HTTP and TCP/IP protocols. Messages are exchanged using XML format [6]. In order to save the number of IP address, the system uses 1 IP address for the whole village in which all homes and appliance in this village are addressed using internal identification numbers. This proposed system gives the data transfer accuracy over 99.8% and maximum polling time is 1,120 ms.

• Sleep Medicine and Psychophysiology
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• v.6 no.1
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• pp.19-25
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• 1999

Sleep alters both breathing pattern and the ventilatory responses to external stimuli. These changes during sleep permit the development or aggravation of sleep-related hypoxemia in patients with respiratory disease and contribute to the pathogenesis of apneas in patients with the sleep apnea syndrome. Fundamental effects of sleep on the ventilatory control system are 1) removal of wakefulness input to the upper airway leading to the increase in upper airway resistance, 2) loss of wakefulness drive to the respiratory pump, 3) compromise of protective respiratory reflexes, and 4) additional sleep-induced compromise of ventilatory control initiated by reduced functional residual capacity on supine position assumed in sleep, decreased $CO_2$ production during sleep, and increased cerebral blood flow in especially rapid eye movement(REM) sleep. These effects resulted in periodic breathing during unsteady non-rapid eye movement(NREM) sleep even in normal subjects, regular but low ventilation during steady NREM sleep, and irregular breathing during REM sleep. Sleep-induced breathing instabilities are divided due primarily to transient increase in upper airway resistance and those that involve overshoots and undershoots in neural feedback mechanisms regulating the timing and/or amplitude of respiratory output. Following ventilatory overshoots, breathing stability will be maintained if excitatory short-term potentiation is the prevailing influence. On the other hand, apnea and hypopnea will occur if inhibitory mechanisms dominate following the ventilatory overshoot. These inhibitory mechanisms include 1) hypocapnia, 2) inhibitory effect from lung stretch, 3) baroreceptor stimulation, 4) upper airway mechanoreceptor reflexes, 5) central depression by hypoxia, and 6) central system inertia. While the respiratory control system functions well during wakefulness, the control of breathing is commonly disrupted during sleep. These changes in respiratory control resulting in breathing instability during sleep are related with the pathophysiologic mechanisms of obstructive and/or central apnea, and have the therapeutic implications for nocturnal hypoventilation in patients with chronic obstructive pulmonary disease or alveolar hypoventilation syndrome.

• BMB Reports
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• v.41 no.10
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• pp.716-721
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• 2008

To explore the effects of deregulated expression of the EBNA1 binding protein 2 (EBP2) on cell growth, we generated human HEK293 stable clones constitutively expressing an EBP2-EGFP fusion protein. We found both RNA and protein levels of cyclin E1, a dominant oncoprotein, were elevated in the EBP2- EGFP stable clones. These findings were confirmed by flow cytometry bivariate analysis of cyclin expression versus DNA content. Moreover, the increase in p21 expression and the specific phosphorylation at Ser1981 of ATM and Ser15 of p53 were also observed in these stable clones, and these observations may explain the failure to observe an increase in Cdk2 kinase activity. In addition, after one year of passage culture, the EBP2-EGFP stable clones tended to lose 4 to 5 chromosomes per cell when compared to that of control cells. All of these findings provide a possible link between deregulated expression of EBP2 and tumor development.

• Journal of the Korean Society of Propulsion Engineers
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• v.21 no.3
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• pp.1-9
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• 2017

Numerical computations are performed to investigate the effect of pintle stroke on the performance of an internal pintle thruster. Results show that the thrust control ratio was less than 2% and the aerodynamic load ratio was 22% as the pintle stroke increased. The flow past the nozzle throat rapidly expanding because of the shape of the pintle, and a shock wave was generated. Particularly, at the pintle stroke distance of 4 and 5 mm, the shock wave hit the wall of the nozzle, results in peeling bubbles. Depending on the altitude, the thrust increased and the aerodynamic load decreased, but the difference was as small as 1.5%. In the presence of the bore, the reduction of the pintle tip area resulted in a decrease in aerodynamic load.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.14 no.5
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• pp.2069-2074
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• 2013

The use of the electromagnetic clutch water pump for internal combustion engine vehicles saves fuel and leads to a reduction in emissions. The clutch water pump allows the engine cooling system to select the optimum operation condition by using coolant flow rate on/off control. This study investigated the characteristics of fuel consumption and emissions of the diesel engine cooling system using the clutch water pump. The electromagnetic clutch operation reduced by about 49% of engine warm up period at idle condition and controlled the optimum high coolant temperature at driving condition. Therefore, fuel consumption was enhanced by about 5%, and emissions such as HC, CO and $CO_2$ were also reduced to a certain degree even though NOx increased a little bit, compared to those of the conventional water pump under NEDC mode which represents the real driving pattern.

• Nuclear Engineering and Technology
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• v.48 no.5
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• pp.1083-1095
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• 2016

The design of Prototype Gen-IV Sodium-Cooled Fast Reactor (PGSFR) has been developed and the validation and verification (V&V) activities to demonstrate the system performance and safety are in progress. In this paper, the current status of test activities is described briefly and significant results are discussed. The large-scale sodium thermal-hydraulic test program, Sodium Test Loop for Safety Simulation and Assessment-1 (STELLA-1), produced satisfactory results, which were used for the computer codes V&V, and the performance test results of the model pump in sodiumshowed good agreement with those in water. The second phase of the STELLA program with the integral effect tests facility, STELLA-2, is in the detailed design stage of the design process. The sodium thermal-hydraulic experiment loop for finned-tube sodium-to-air heat exchanger performance test, the intermediate heat exchanger test facility, and the test facility for the reactor flow distribution are underway. Flow characteristics test in subchannels of a wire-wrapped rod bundle has been carried out for safety analysis in the core and the dynamic characteristic test of upper internal structure has been performed for the seismic analysis model for the PGSFR. The performance tests for control rod assemblies (CRAs) have been conducted for control rod drive mechanism driving parts and drop tests of the CRA under scram condition were performed. Finally, three types of inspection sensors under development for the safe operation of the PGSFR were explained with significant results.

• Journal of Veterinary Clinics
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• v.20 no.4
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• pp.437-442
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• 2003

To examine the in vivo immunostimulating effect of conjugated linoleic acid (CLA) in pigs, the change of peripheral blood cells and the phagocytic response of phagocytes were evaluated. Spayed male pigs, 80 kg of average body weight, fed a diet containing either 0.5% 10t-12c CLA or 0.5% CLA mixture (mostly 9c-11t CLA and 10t-12c CLA) for 4 weeks. The change of blood cell values (PCV, WBC, differential count of WBC) and the phagocytic activities of phagocytes were evaluated on week 0, 2, 4, and 5, respectively. There were no change in the PCV values regardless of CLA supplement. The number of WBC, especially neutrophils, in pigs fed a diet with CLA was significantly increased (p<0.05 to 0.01) when compared with control pigs fed a diet without CLA. The phagocytosis of peripheral blood mononuclear cell (MNC) and peripheral blood polymorphonuclear cells (PMN) were analyzed by a flow cytometry system. There was no change in the phagocytic activity of MNC and monocyte-rich cells regardless of CLA supplement. However, the phagocytic activity of PMN composed by approximately 95% neutrophils was remarkably increased (p < 0.05 to 0.01) on week 2, 4, and 5 as compared wth control pigs. These results suggested that supplement of CLA into pigs induces the increase of neutrophil number and the enhancement of neutrophil phagocytosis.