• Journal of Life Science
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• v.23 no.12
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• pp.1471-1476
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• 2013

The present study deals with the immobilization of Kluyveromyces lactis ${\beta}$-galactosidase on a weak ionic exchange resin (Duolite A568) as polymer support. ${\beta}$-Galactosidase was immobilized using the adsorption method. A kinetic study of the immobilized enzyme was performed in a packed-bed reactor. The adsorption of the enzyme followed a typical Freundlich adsorption isotherm. The adsorption parameters of k and n were 14.6 and 1.74, respectively. The initial rates method was used to characterize the kinetic parameters of the free and immobilized enzymes. The Michaelis-Menten constant ($K_m$) for the immobilized enzyme (120 mM) was higher than it was for the free enzyme (79 mM). The effect of competitive inhibition kinetics was studied by changing the concentration of galactose in a recycling packed-bed reactor. The kinetic model with competitive inhibition by galactose was best fitted to the experimental results with $V_m$, $K_m$, and $K_I$ values of 46.3 $mmolmin^{-1}mg^{-1}$, 120 mM, and 24.4 mM, respectively. In a continuous packed-bed reactor, increasing the flow rate of the lactose solution decreased the conversion efficiency of lactose at different input lactose concentrations. Continuous operation of 11 days was conducted to investigate the stability of a long-term operation. The retained activity of the immobilized enzymes was 63% and the half-life of the immobilized enzyme was found to be 15 days.

• Korean Journal of Agricultural and Forest Meteorology
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• v.10 no.4
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• pp.132-140
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• 2008

Two different sensitivity classes of black cherry (Prunus serotina) under the natural growing environmental conditions were assessed adjacent to Air Monitoring Station located at Horton research center in Giles County, Virginia, USA. Ambient ozone concentrations, leaf gas exchange, and visible foliar injury were measured on-site during the growing seasons of 2000, 2001, and 2002. Ambient ozone exposures were sufficient to induce typical foliar visible injury corresponding with the reduction in photosynthetic activities only in sensitive black cherry. There were positive correlations between increasing cumulative ozone concentration and percent reduction in maximum net photosynthetic rates ($Pn_{MAX}$) under saturating light conditions and in quantum yield for carbon reduction (${\Phi}CO_2$) of sensitive black cherry compared to tolerant black cherry. There was a negative correlation between chlorophyll content and percent leaf injury in sensitive black cherry. Furthermore, $Pn_{MAX}$ was inversely related to percent leaf injury.

• Korean Journal of Construction Engineering and Management
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• v.9 no.4
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• pp.173-181
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• 2008

Last decade, Korea's export scale has resulted in remarkably increasing tendency, and the Korean construction firms(KCFs)' activities on the global markets also have been revitalized. Therefore, this paper analyze a correlation between changes in the oversee market conditions and firms' competitiveness focused on plant business. The aim of this paper is to analyze the internal competency change of the KCFs on the global markets in the past 5 years and to find gap of internal competencies between KCFs and outstanding foreign firms. From a survey analysis this paper found that the external impacts on the global markets(changes of exchange rates, raw materials prices, supply-demand conditions, etc.) have highly influenced the sales amount of the KCFs. But the impacts to change the operating profit have been analyzed as not important. So it is necessary to reinforce the KCF's internal competencies rater than expecting an improvement of the external conditions. Also, the KCFs should strengthen the design engineering as a core competency.

• The Journal of the Korean dental association
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• v.53 no.4
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• pp.266-274
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• 2015

The price for health service are decided by very complicated process because many of factors are related with them. The RBRVS(resource-based relative value scale) were used to calculate the Korean health service fees including dental fees. This study aimed to compare dental fees of Korea with other countries, such as Japan, Germany, and the US for evaluating the adequacy. Dental fees were categorized as oral evaluation and imaging, dental treatment including restorative, periodontal, and surgical work, and preventive treatment and compared by each country. The official documents about dental fees were collected from Korea, Japan, Germany, and the US. Each fee was presented as their own currency at first. Then they were converted into Korean won (KRW) by applying the market exchange rates at a specific point of time. Finally the fees were adjusted by purchasing power parities (PPPs) which equalize the different currencies. In general, the level of Korean fees were markedly low compared to those of Japan, Germany, and the US. German fees were similar or higher than that of Japan, and the US. The Korean fees were lower than three other countries 1.2~4.1 times for oral evaluation and 2.2~7.3 times lower for panoramic radiography. The endodontic fees of Japan, Germany, and the US were higher 1.8~15.3 times and 4.0~35.9 times for the deciduous teeth extraction compared to the Korean. In Japan the prophylaxis was 3.2 times more priced than the Korean fee. Exceptionally, the fees for re-evaluation, amalgam filling, and scaling were lower priced in Japan than other countries. This study has limitations on the items in definition and contents of dental practices units which were not exactly comparable and differently determined by countries. However, this study is meaningful because it surveyed the price levels to compare four different countries and then applied PPPs adjustment. This finding can be used to develop the dental RBRVs of Korean national health insurance and will contribute to improving the payment systems of health care.

• Journal of the Korean Data and Information Science Society
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• v.28 no.4
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• pp.831-841
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• 2017

The irrational number ${\pi}$ is defined as the ratio of circumference of a circle to its radius and always becomes constant. This article does Monte Carlo approximation of its value using the famous Buffon's needle experiment and shows that its convergence is not always proportional to the sample size. We also do Monte Carlo simulations to see the convergence of the computed ${\pi}$ values from the random walk series with independent normal increment. Finally we apply the theoretical derivation to various financial time series data such as KOSPI, stock prices of Korean big firms, global stock indices and major foreign exchange rates. The historical data shows that log transformed data random walk process but most of their first lagged data don't follow a normal distribution. More importantly the computed value from the ratio of the regression coefficient ${\pi}$ tend to converge a constant, unfortunately not ${\pi}$. Using this result we could doubt on the efficient market hypothesis, and relate the degree of the hypothesis with the amount of deviation of the estimated ${\pi}$ values.

• Journal of Photoscience
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• v.12 no.1
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• pp.17-23
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• 2005

Application of a new photocatalyst has been attempted to improve the efficiency and rates of photocatalytic degradation of azo dyes by using a model dye such as Methyl Orange. As a new photocatalyst, $TiO_2$ encapsulated EFAL-removed zeolite Y ($TiO_2$ /EFAL-removed zeolite Y) has been synthesized by ion-exchange in the mixture of EFAL-removed zeolite Y with 0.05 M aqueous [$(NH_4)_2 TiO(C_2O_4)_2.H_2O$] [$TiO(C_2O_4)_2.H_2O$]. This new photocatalyst has been characterized by measuring XRD, IR and reflectance absorption spectra as well as ICP analysis, and it was found that the framework structure of $TiO_2$ /EFAL-removed zeolite Y is not changed by removing the extra-framework aluminum (EFAL) from the normal zeolite Y and the $TiO_2$ inside the photocatalyst exists in the form of $(TiO^{2+})_n$ nanoclusters. Based on the ICP analysis, the Si/Al ratio of the $TiO_2$ /EFAL-removed zeolite Y and the weight of $TiO_2$ were determined to be 23 and 0.061g in 1.0g photocatalyst, respectively. It was also found that adsorption of the azo dye in the $TiO_2$ /EFAL-removed zeolite is very effective (about 80 % of the substrate used). This efficient adsorption contributes to the synergistic photocatalytic activities of the $TiO_2$ /EFAL-removed zeolite by minimizing the required flux diffusion of the substrate. Thus, the photocatalytic reduction of methyl orange (MO) was found to be 8 times more effective in the presence of $TiO_2$ /EFAL-removed zeolite Y than in the presence of $TiO_2$ /normal zeolite Y. Furthermore, the photocatalytic reduction of MO by using 1.0 g of the $TiO_2$ /EFAL-removed zeolite Y containing 0.061g of $TiO_2$ is much faster than that carried out by using 1.0 g of Degussa P-25.

• Korean Journal of Food Science and Technology
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• v.34 no.6
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• pp.998-1001
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• 2002

Micro-LC method for the quantitative determination of hydrogen peroxide in foods has been established. This method was carried out on cation-exchange resin gel column using distilled water as mobile phase with 50 mM sodium sulfate as electrolyte. The detection was performed with an electrochemical detector (ECD) at 0.6 voltage. Under this analytical condition, the recovery rates of hydrogen peroxide in tomato and lemon were 98.3 and 97.4%, respectively. Among 28 food types, hydrogen peroxide concentrations were 0.6, 0.5, 1.9, 0.9, 0.5, 0.6, 0.9, 0.8, and 0.4 ppm in banana, peach, orange, strawberry, pepper, onion, cucumber, burdock, and egg plant, respectively, Whereas none was detected in remaing 19 samples.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.9
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• pp.464-471
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• 2016

To investigate the effects of cardiac rehabilitation (CR) on cardiopulmonary exercise capacity in both elderly and younger patients with myocardial infarction (MI). Of the MI patients who received hospital-based CR between February 2012 and December 2015, we retrospectively reviewed the medical records of patients who continued a follow-up through the outpatient clinic. A total of 46 patients (18 elderly patients (${\geq}60years$) and 28 younger patient (< 60)) were included in this study. The subjects visited the clinic to perform aerobic exercises with ECG monitoring based on their initial exercise tolerance test outcome. The exercise capacity was measured by symptom-limited exercise tests before and after hospital-based CR. Before CR, the elderly group had a significantly lower exercise capacity in peak VO2, METs, anaerobic threshold, exercise time, respiratory exchange ratio (RER) than the younger group. After CR, elderly groups showed a significantly improved exercise capacity in exercise time, HRmax, HRrest, peak VO2, METs, anaerobic threshold, and RER. Both elderly and younger groups showed similar improvement of cardiopulmonary exercise capacity after hospital-based CR. There is a very low cardiac rehabilitation participation and referral rates with MI patients in Korea. It is considered necessary to further expand the participation of cardiac rehabilitation in elderly MI patients.

• International Area Studies Review
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• v.15 no.2
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• pp.77-100
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• 2011

The Korean economy have experienced the remarkable decreases in factor prices such as bond yields, real wage since the IMF foreign exchange crisis. This paper investigates the effects of the price changes in the factor markets on determining the level and cyclicality of industrial markups in the manufacturing industry. For this purpose, we construct a markup equation in the small open economy based on the production function including foreign intermediate goods and assuming constant returns to scale technology and AR(1) process of technological coefficient. Empirical results are summarized as the followings. The empirical results shows that the increased markups after the IMF crisis can be explained by the price decreases in the factor markets which result in lowering marginal costs. And we also observed counter cyclicality of markup, labor share and interest rates while real wages, technical coefficients, and production price index proved to be pro-cyclical. In conclusion, the price changes in factor market have contributed to the stickiness in markup fluctuation in the manufacturing industry.

• International Area Studies Review
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• v.13 no.3
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• pp.413-438
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• 2009

Tourism is an attractive field of industry to many countries due to its strong potentials in increasing employment rates as well as improving the national image. The positive effect of the tourism on the national economy and globalization has been recognized in Korea. A multilateral effort has been made in order to develop its tourist industry. Therefore, it is necessary to analyze the patterns of tourism demand in Korea. The present study analyzes and demonstrates the effects of a nation's characteristics on tourism demand. The study model was based on factors that affected tourism demand, especially emphasizing on the economic size, distance, national income, and language differences from the mother country. In particular, this study highlights the effects of economic relations between the countries and their exchange rate on tourism demand. In summary, this thesis demonstrates that actual national and international panel data enhance the credibility of the research and precisely determine factors that have a direct influence on tourism demand. A corresponding strategy of development and products are required as most tourists show the preference in advanced nations.