• Journal of Chest Surgery
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• v.33 no.8
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• pp.613-622
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• 2000

Background: The aim of this study is to define the cardioprotective effects(functional and metabolic) of newly developed DelNido cardioplegic solution(containing plasma solution, mannitol, magnesium and lidocaine). Material and Method: This study assessed the function of rat hearts after itermittent infusion of DelNido cardioplegia with different preserving methods(Air or Icebox) for 2hours and perfusing the hearts on a Langendorff apparatus. Heart rate, left ventricular developed pressure(LVDP) and coronary flow, were measured at pre-ischemic, post-reperfusion 15min, 30min and 45min. Coronary flow was standardized to dry heart weight. Each weight was weighted to calculate water content. Creatine kinase-MB isoenzyme release was measured and ultrastructural assessment was done with electron microscopes. Result: DelNido group was better than St, Thomas group and Icebox group was better than Room-air group. Conclusion: DelNido cardioplegia have better myocardial protective effects than St. Thomas cardioplegia when they were preserved in the Room-air. But we can not tell the difference between Delnido cardiplegia with Air preserving method and St. Thomas cardioplegia with Icebox.

• Transactions of the Korean Society of Automotive Engineers
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• v.11 no.5
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• pp.15-21
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• 2003

The liquid phase LPG injection engine is a new technology to make good use of LPG as a clean energy. However, it is difficult to precisely control air/fuel ratio in the system because of variation of fuel composition, change of temperature and flash boiling injection mechanism. This study newly suggests an injector control logic for liquid phase LPG injection systems. This logic compensates a number of effects such as variations of density, stoichiometric air/fuel ratio, injection delay time, injection pressure, release pressure which is formed by flash boiling of fuel at nozzle exit. This logic can precisely control air/fuel ratio with only two parameters of intake air flow rate and injection pressure without considering fuel composition, fuel temperature.

• Journal of the Korean Society of Safety
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• v.11 no.4
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• pp.107-114
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• 1996

A study to Improve the safety of the ceramic heat exchanger In the high temperature heat recovery system was performed in terms of air flow passes. The numerical and finite element analyses on the heat transfer and thermal stresses in the ceramic core related with air passes were carried out. The results showed that the stresses in the ceramic core induced by the thermal expansion are large enough to cause failure of the brittle ceramic core. The imployment of triple-pass air flow for the same ceramic core could increase the efficiency and effectively release approximately 20% of the maximum thermal stressess, thus improving the safety of the ceramic heat exchanger. The use of triple-pass, however, is limited by the amount of air flow due to the increase of pressure drop.

• The Magazine of the Society of Air-Conditioning and Refrigerating Engineers of Korea
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• v.17 no.4
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• pp.369-376
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• 1988

Among several methods to solve the unbalanced electric power load, the Ice Storage System (ISS) for the air conditioning is relatively easy to realize and gives big effect on balancing the electric power load. The goals of this study are to develop the practical ISS for the air conditioning through the design, manufacturing and performance test of the experimental ISS (size $0.335m^3$, cold storage capacity 14200 kcal, IPF 0.4). Thermal fluid motion inside the ice storage tank during cooling storage and cooling release are studied. The data are analyzed by the dispersion analysis and optimal design conditions are derived from the result.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.27 no.7
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• pp.1007-1014
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• 2003

This work deals with a controlled auto-ignition (CAI) single cylinder gasoline engine, focusing on the extension of operating conditions. The fuel is injected indirectly into electrically heated inlet air flow. In order to keep a homogeneous air-fuel mixing, the fuel injector is water-cooled by a specially designed coolant passage. Investigated are the engine performance and emission characteristics under the wide range of operating conditions such as 32 to 63 in the air-fuel ratio, 1000 to 1800 rpm in the engine speed, and 150 to 18$0^{\circ}C$ in the inlet air temperature. The compression ignition gasoline engine can be achieved that the ultra lean-burn with self-ignition of gasoline fuel by heating inlet air. For example. the allowable lean limit of air-fuel ratio is extended until 63 at engine speed of 1000 rpm and inlet air temperature of 17$0^{\circ}C$. It can be achieved that the emission concentrations of carbon monoxide, hydrocarbons and nitrogen oxide had been significantly reduced by CAI combustion compared with conventional spark ignition engine.

• Korean Journal of Applied Biomechanics
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• v.19 no.1
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• pp.37-47
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• 2009

This study develops a technique training program to enhance the completion of Kolman, the high air flight technique, and applies it to two national athletes of the horizontal bar, one of the gymnastic events, for eight weeks. After that, their improvement was measured through 3D motion analysis to help them elevate their performance. The training program includes swing, hand release, twist, and bar hold, and its implementation produced the results stated below. They were made to practice the motion in the following way. After the hand-standing of giant swing which initiates the motion, they lift their body upward a little bit more. Next, they take their body down almost like a vertical descent and make a deep tap swing. Instead of doing the tap swing which widens the flection of hip and shoulder joints, while body revolution is more emphasized in particular, they release the bar as raising the centroid of their body sufficiently. During the flight, they try to narrow every joint in their body. As a result, the bar's elasticity becomes greatly increased, and since the backing rate of their body gets higher, the centripetal force of the swing is improved that they can release the bar in the higher position. In addition, because they can erect their body faster during the flight, they can perform comfortable twist and revolution in the air. They can also adjust the direction of the flight easily without too much concern for the proper timing of hand release as they rise. Thereby, they can not only maintain adequate distance from the bar for the bar hold but also ensure enough distance for body revolution and twist.

• Journal of Radiation Protection and Research
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• v.39 no.2
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• pp.89-95
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• 2014

In potential accident consequence assessments for the licensing approval of LWRs, the ground deposition of radionuclides released into the environment is not allowed into the models, as recommended in the U. S. Nuclear Regulatory Commission's regulatory guide. Meanwhile, it is allowed into the assessment models for the licensing approval of PHWRs with consideration of more detailed physical processes of radionuclides in the atmosphere. Under these backgrounds, importance of exposure dose by ground deposition was quantitatively evaluated and comprehensively discussed. For potential accidental releases of $^{137}Cs$ and $^{131}I$, total exposure doses were more conservative in case of without consideration of ground deposition than in case of with its consideration. It was because of that the depletion of air concentration resulting from ground deposition is more influential in the contribution to total exposure doses than additional doses from contaminated ground. The exposure doses by the inhalation of contaminated air showed the contribution of more than 90% in total exposure doses, depending on atmospheric stability, release period of radionuclides and distance from a release point. The exposure doses from contaminated ground showed less than 10% at most in contribution of total exposure doses. The ratios of total exposure doses in case of with consideration of deposition to without its consideration for $^{131}I$ were distinct than those for $^{137}Cs$. As the atmosphere is more stable, release duration of radionuclides is longer, distance from a release point is longer, it was more distinct.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.27 no.11
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• pp.1630-1636
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• 2003

Automobile companies and research institutions in leading automobile-manufacturing nations have recently been very active with research regarding the HCCI engine for use in future vehicles. Because HCCI engines take advantage of high compression ratio and heat release rate, they exhibit high efficiency found in compression ignition engines. HCCI engines also utilize a lean air/fuel ratio resulting in low emissions of NO$_{x}$ and PM (particulate matter). The objective of this research is to determine the effects of EGR rate on the combustion processes of HCCI. for this purpose, a 4-cylinder, compression ignition engine was converted into a HCCI engine, and a heating device was installed to raise the temperature of the intake air and also to make it more consistent. In addition, a pressure sensor was inserted into each of the cylinders to investigate the differences in characteristics among the cylinders. The experimental study of the effects of EGR rate on various gas emissions, engine performance, etc. should prove to be a valuable source of information for the development of the HCCI engine.e.

• Journal of Advanced Marine Engineering and Technology
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• v.18 no.1
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• pp.81-91
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• 1994

Combustion noise involved with chemical heat release and turbulent process in turbopropulsion systems, gasturbine, industrial furnaces and internal engines is indeed noisy. The experimental study reported in this paper is made to identify a dominant combustion noise in jet flames. Gaseous propane and kerosene fuel have been used with air as the oxidizer in a different jet combustion systems. Combustion and aerodynamic noise are studied through far field sound pressure measurements in an anechoic chamber. And also mean temperature and velocities and turbulent intensities of both isothermal and reacting flow fields were measured. It is shown that axial mean velocity of reacting flow fields is higher about 1 to 3m/sec than that of cold flow in a gaseous combustor. As the gaseous fuel flow rate increases, the acoustic power increases. But the sound pressure level for the spray flame decreases with increasing equivalence ratio. The influence of temperature in the combustion fields due to chemical heat release has been observed to be a dominant noise source in the spray flame. The spectra of combustion noise in gaseous propane and kerosene jet flame show a predominantly low frequency and a broadband nature as compared with the noise characteristics in an isothermal air jet.

• Transactions of the Korean Society of Automotive Engineers
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• v.13 no.5
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• pp.188-194
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• 2005

The direct injection diesel engine is one of the most efficient thermal engines. For this reason DI diesel engines are widely used for heavy-duty applications. But the world is faced with very serious problems related to the air pollution due to the exhaust emissions of diesel engine. So, that is air pollution related to exhaust gas resulted from explosive combustion should be improved. Exhaust Gas Recirculation(EGR) is a proven method to reduce NOx emissions. In this study, the experiments were performed at various engine loads while the EGR rates were set from $0\%$ to $30\%.$ The emissions trade-off and combustion of diesel engine are investigated. The brake specific fuel consumption rate is very slightly fluctuated with EGR in the range of experimental conditions. The ignition delay increased with increasing EGR rate. The maximum value of premixed combustion for the rate of heat release is increased with increasing EGR rate. NOx emissions are decreased with increasing EGR rate at high load and high speed. It was found that the exhaust emissions with the EGR system resulted in a very large reduction in oxides of nitrogen at the expense of higher smoke emissions.