• Proceedings of the Korean Society of Applied Pharmacology
• /
• 1997.11a
• /
• pp.41-46
• /
• 1997

Lower esophageal sphincter (LES) is characterized by the ability to maintain a sustained pressure, and to relax allowing the passage of a bolus, whereas the esophagus is normally relaxed and contracts only briefly when required to produce peristalsis (fig. 1). The neuromuscular mechanisms that participate in the physiological regulation of these functions are not well understood, but it is thought that LES tone is spontaneous and regulated mostly through myogenic mechanisms, whereas LES relaxation and esophageal contraction are induced by neural mechanisms. Gastroesophageal reflux represents the effortless movement of gastric contents from stomach to esophagus. Because this phenomenon occurs in virtually everyone multiple times every day and in the majority of people without clinical consequences, the reflux per se is not disease. However in some cases, it can be pathologic, producing symptoms and signs called gastroesophageal reflux disease (GERD), which mechanism is not well known. It may result in heart burn, chronic esophagitis, aspiration pneumonia, esophageal strictures, and Barrett's esophagus.

• Journal of Advanced Marine Engineering and Technology
• /
• v.21 no.3
• /
• pp.302-310
• /
• 1997

In this paper, we find a method to improve ignitability using methanol which is prospective as an alternative fuel. The constant volume combuster is divided into main chamber and sub-cham¬ber. These two chambers are linked by an adapter which is shaped like a cup. We also compare CDI to HIS that is revised in our laboratory for making a scrutiny into the effects of ignition char¬acteristics. Besides, we analyze a flame propagation process in the main and sub-chamber through taking pictures 10, 000 frames per second by high speed camera at the state being fabricated quartz glass aside main and sub-chamber.

• Carbon letters
• /
• v.6 no.3
• /
• pp.141-147
• /
• 2005

The carbon sample "O", phosphoric acid-activated carbon "OP", zinc chloride-activated carbon "OZ", and two steam activated carbons "OS" and "OS2" with different burn-off of 25% and 58% respectively, were prepared from olive stones. The textural properties were determined from the results of nitrogen adsorption at 77 K and by analyzing these results through the application of different adsorption models. The chemistry of the carbon surfaces was determined from the base neutralization capacities, acid neutralization capacity and surface pH. The sorption of $Pb^{2+}$ ions on to the carbons prepared was followed under dynamic and equilibrium conditions. The differences between the values of the textural parameters were attributed to the inapplicability of some adsorption models and to the heterogeneity of the microporous carbons. The sorption of $Pb^{2+}$ ions is favored on carbon and activated carbons. However, chemically activated carbons are more effective compared with steam-activated ones. The sorption of $Pb^{2+}$ ions were related to the chemistry of the surface rather than to the textural properties.

• 한국전산유체공학회:학술대회논문집
• /
• 2008.03b
• /
• pp.695-698
• /
• 2008

Self-blast circuit breakers utilize the energy dissipated by the arc itself to create the required conditions for arc quenching during the current zero. During the arcing period, high pressure, temperature and radiation of the arc could burn in pure SF6 gas and PTFE nozzle. Ablated nozzle shape and $SF_6$-PTFE mixture vapor affect the performance of an self-blast circuit breaker. After a number of tests, nozzle in circuit breaker is disassembled, a section of ablated nozzle is investigated precisely. Using computational fluid dynamics, the conservation equation for the gas and temperature, velocity and electric fields within breaker is solved. Before applying a section model, developed program is verified with experimental data. Performance of ablated nozzle shape is compared with original model through analysis program.

• Proceedings of the KIPE Conference
• /
• 2002.07a
• /
• pp.665-668
• /
• 2002

Joining thin aluminum alloy is difficult using most wilding techniques. Many of problems associated burn-through by the high heat input Common welding techniques are TIG, MIG, and MIG-PULSE welding. The VP-GMAW provides more control of the heat balance in the voiding arc by taking advantage of the different arc characteristics obtained with each of the two polarities. In this paper, we proposed new VP_GMA Welding method by control DSP 320C32, and the characteristic and experiment result-voltage, current, welding bead. penentraion by this method are presented

• Transactions of the Korean Society of Automotive Engineers
• /
• v.9 no.4
• /
• pp.85-91
• /
• 2001

LPG has been well known as a clean alternative fuel for vehicles. As a fundamental study on liquid phase LPG injection (hereafter LPLI) system application to heavy-duty engine, engine output and combustion performance were investigated with various operating conditions using a single cylinder engine equipped with the LPLI system. Experimental results revealed that no problems were occurred in application of the LPG fuel to heavy-duty engine, and that volumetric efficiency and engine output, by 10% approximately, were increased with the LPLI system. It was resulted from the decrease of the intake manifold temperature through liquid phase LPG fuel injection. These results provided an advantage in the decrease of the exhaust gas temperature, in the control of knocking phenomena, spark timing and compression ratio. The LPLI engine could normally operated under $\lambda$=1.5 or EGR 30% condition. The optimized swirl ratio for the heavy duty LPG engine was found around R_s$ = 2.0.

• Proceedings of the KWS Conference
• /
• 2003.05a
• /
• pp.155-158
• /
• 2003

Orbital GTA welding is used in the pressure pipe line of auto-mobile, LNG and plant piping. To weld the pipe line safely, to some extent, the back bead must be formed in the root pass. In the plate welding the back bead can be observed, but in the pipe welding, the back bead can not be observed directly. In the welding around circumference, the parameters such as gravity, surface tension and arc force are different at each position. And then D/B for welding condition at each position are required. We also studied about the setting of the optimum orbital welding condition by controlling heat input.

• Journal of Korean Society of Industrial and Systems Engineering
• /
• v.28 no.4
• /
• pp.124-133
• /
• 2005

The purpose of this study is to analyze the effectiveness of process approach for business performance of a company certified with ISO 9000 : 2000 quality management system. The result of this empirical research were identified as follows. Documentation and an intelligence process appeared with a preference matter in an influence to reach to a business performance of a company through the organization which established a process approach. It reveals that the process approach of quality management system might affect positively for customer satisfaction, product qualify, financial results and cost reduction.

• Nuclear Engineering and Technology
• /
• v.42 no.3
• /
• pp.237-248
• /
• 2010

The safety of metal cask and concrete cask storage technology has been verified by CRIEPI through several research programs on demonstrative testing for the interim storage of spent fuel. The results have been reflected in the safety requirements for dry casks issued by NISA/METI (Nuclear and Industrial Safety Agency, Ministry of Economy, Trade and Industry) of the Japanese government. On top of that, spent fuel integrity has been studied by the Japan Nuclear Energy Safety Organization (JNES). This paper reviews these research programs. Future issues include the long-term integrity of cask components and high burn-up spent fuel.

• Transactions of the Korean Society of Mechanical Engineers
• /
• v.19 no.9
• /
• pp.2308-2315
• /
• 1995

We studied the effects on the ignitability of mixture, the combustion duration, and the maximum combustion pressure, of various initial combustion factors such as temperature, pressure, and each equivalence ratio in order to identify the combustion characteristics of lean mixture and improve ignitability through the proper control of the ignition energy. It is concluded that there is an optimum turbulent intensity that enables the combustion to have the best ignitability and the shortest duration under each equivalent ratio, and the combustion duration is only dependent upon the distribution and magnitude of discharge energy within the limit of inflammability.