• Journal of the Economic Geographical Society of Korea
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• v.17 no.1
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• pp.147-159
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• 2014

The present study was aimed to estimate the rational bubble by using the state space model and Kalman filter, of the national, capital, non-capital, Gangnam, and Gangbuk regions housing sales price from November 2003 to August 2013, for the whole period, and before and after the global financial crisis. For the whole period, Gangnam marked the highest rational bubble of 25.4%, followed by Gangbuk 21.3%, capital region 20.1%, whole country 18.9%, and non-capital region 14.3%. Prior to the global financial crisis, Gangnam showed 26.7% of bubble, which is approximately 7.4% higher than Gangbuk with 19.3%. On the other hand, after the global financial crisis, the bubble has collapsed a lot with Gangnam 13.2% and Gangbuk 10.7%; however, the non-capital region showed rather an increase of about 15% from 4.2% before the crisis to 9.0% after the crisis. The main cause of this is that the trading price has declined but the rents have risen in the capital region including Gangnam and Gangbuk, while the transaction price has gone up in non-capital region due to various positive signs like the moving of public institutions.

• Journal of Korean Society of Environmental Engineers
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• v.39 no.10
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• pp.549-555
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• 2017

The purpose of this study is to investigate how ozone-dissolution-tank structure affects micro-ozone-bubble distribution, energy consumption and water treatment efficiency. The partition walls inside the ozone-dissolution-tank generate pressure changes, shear forces, and swirling flows, which change the size of the bubble diameter. The size of the bubble diameter differs by 10.5% depending on the partition walls. Changes in ozone-bubble diameter are related to energy consumption. As the ozone-bubble becomes smaller, the bubble generation energy increases, but the ozone production energy decreases as the dissolution efficiency increases. Therefore, an ozone-dissolution-tank should be determined by means of an optimal condition producing a micro-ozone-bubble with a minimum sum of bubble generation energy and ozone production energy. The energy consumed to inject the same amount of ozone into the effluent differs by 2.5% depending on the partition walls. However, considering the water treatment efficiency, the conditions for selecting the ozone-dissolution-tank are variable. This is because the free radicals that increase as the ozone-bubble gets smaller are very efficient for water treatment. Even at the same ozone injection concentration, the water treatment efficiency differs by 10.4% according to the partition walls. Therefore, we have studied ozone-dissolution-tank structure which produces reasonable ozone-bubble considering water treatment efficiency and energy efficiency.

• KDI Journal of Economic Policy
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• v.35 no.2
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• pp.107-131
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• 2013

In this paper, we test and estimate the stochastic non-fundamental trend in Korean stock market. For this, following Kim (2011), we exploit that the long-run equilibrium stock price may be decomposed into fundamental and stochastic non-fundamental trends (i.e., the sum of dividend innovations and a part that are orthogonal with the dividend innovations) by using the Beveridge-Nelson decomposition and projections. In this VAR construction, there is an error correction mechanism through which stock prices converge to their long-run equilibrium, which also contain the stated stochastic non-fundamental trend as well as fundamental trend. The estimation and test results using yearly data from the Korea (1976-2012) indicated that fluctuations in stock prices during that period can be explained mainly not by the stochastic non-fundamental trend but by the dividend trend. However, during some periods like after Seoul Olympic Games, we may observe the non-fundamental trend affected to the stock price variation.