• Transactions of the Korean Society of Automotive Engineers
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• v.10 no.3
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• pp.61-69
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• 2002

To meet stringent LEV and ULEV emission standards, a considerable amount of development work was necessary to ensure suitable efficiency and durability of catalyst systems. The main challenge is to cut off the engine cold-start emissions. It is known that up to 80% of the total hydrocarbons(THC) are exhausted within the first five minutes in case of US FTP 75 cycle. Close-Coupled Catalyst(CCC) provides fast light-off temperature by utilizing the energy in the exhaust gas. However, if some malfunction occurred at engine operation and the catalyst temperature exceeds 1050$\^{C}$, the catalytic converter is deactivated and shows the poor conversion efficiency. This paper presents effEcts of engine operating conditions on catalytic converter temperature in a SI engine, which are the indications of catalytic deactivation. Exhaust gas temperature and catalyst temperature were measured as a function of air/fuel ratio, ignition timing and misfire rates. Additionally, light-off time was measured to investigate the effect of operating conditions. It was found that ignition retard and misfire can result in the deactivation of the catalytic converter, which eventually leads the drastic thermal aging of the converter. Significant reduction in light-off time can be achieved with proper control of ignition retard and misfire, which can reduce cold-start HC emissions as well.

• Strategy21
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• s.32
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• pp.160-191
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• 2013

This article is focused how the maritime strategy between continental powered country(the Soviet, the China) and maritime powered country(the U.S.) interact with attack and defense theory. We will know, what is the maritime strategy that the U.S. of military superiority has pursued with the point of view of attack, on the other hand, relatively what is the maritime strategy that the Soviet-Sino of military inferiority has pursued with the point of view of defense. In cold war, the Soviet has counteracted to 'blue belt defense' in active defense as to the U.S. 'sea strike' and in post cold war, the China counteract to 'A2/AD' as to the U.S. 'Air-Sea Battle'. The difference between the Soviet-Sino maritime strategy is that the China has emerged the second an economic power and their leadership has a strong's will to strengthen their navy's power. although the U.S. declare the pivot to Asia, the influence on Asia of the U.S. tend to decrease because of sequest. therefore, the China will seek to the more active defense beyond the first island chain. Meanwhile, the U.S. has reinforced of 'hub and spoke strategy' to solidify the U.S. formal allies to band together regional powers and to overcome the A2/AD challenge, the U.S. has been developed that the Air-Sea Battle concept meshes with Washington's 'rebalancing' policy toward the Asia-Pacific as its vital missions to safeguard core island or semi-island allies-namely, Korea and Japan-and crucial sea lanes of communication in the region are conducted mostly from or over the sea.

• Tuberculosis and Respiratory Diseases
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• v.51 no.3
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• pp.232-239
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• 2001

Background : Asthmatic patients frequently suffer cold-weather-associated respiratory symptoms. The sensitivity, specificity, accuracy and diagnostic value of isocapnic hyperventilation of cold air(IHCA) using a multistep method, was investigated in patients suspected to have asthma. Method : One hundred and 29 adult patients who had an IHCA performed between july 1999 and December 2000, had an methacholine bronchoprovocation test because of a clinical suspicion of asthma. Results : According to strict criteria, 50 were defined as asthmatics and 79 as symptomatic nonasthmatics. There were no differences in age, sex and smoking state between the asthmatic and symptomatic nonasthmatic groups. There was a significant decrease in the percentage reduction in the forced expiratory volume in 1 second($FEV_1$) after the IHCA between the asthmatics($-10.0{\pm}6.8%$) and the symptomatic nonasthmatics($-2.3{\pm}2.5%)$. The factors associated with a reactivity to IHCA were $FEV_1$/FVC, $FEF_{25-75}$%/FVC and $FEV_1$(% of predicted). The accuracy was highest using a 7% fall in $FEV_1$ ; the sensitivity was 76% and the specificity 96%. Conclusion : IHCA is a specific, although not a sensitive, test for diagnosing asthma in adult patients. Furthermore, the diagnostic cut-off value of the different methods of IHCA need to be determined.