• The Journal of Asian Finance, Economics and Business
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• v.7 no.12
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• pp.683-692
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• 2020

The primary purpose of the study is to investigate the volatility spillovers from global economic policy uncertainty and macroeconomic factors to the Islamic stock market returns. The study focuses on the Islamic stock indices of emerging economies including Indonesia, Malaysia, and Turkey. The Macroeconomic factors are industrial production, consumer price index, exchange rate. EGARCH model is employed for investigation of volatility spillovers. The results show that the global economic policy uncertainty has a significant spillover effect only on the returns of Turkish Islamic stock index. Similarly, the shocks in macroeconomic factors have little influence on the volatility of Islamic indices returns. The volatility of Indonesian and the Turkish Islamic stock indices returns is not influenced from the fluctuations in macroeconomic factors. However, there is significant volatility spillover only from industrial production to the returns of Malaysian Islamic index. The results suggest that the Islamic stock markets are less likely to influence from the global economic policies and macroeconomic factors. The stability of Islamic stocks provide opportunity for diversification of portfolios, particularly in stressed market conditions. The major price factors of Islamic markets could be firms' specific factors or investors' behaviors. The findings are helpful for policy makers and investors in formulating policies and portfolios.

• Journal of Pharmaceutical Investigation
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• v.18 no.3
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• pp.125-131
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• 1988

This study was undertaken to investigate the proteolytic enzyme from Neungee mushroom [Sarcodon aspratus (Berk) S. Ito]. The proteolytic activity of Neungee was higher than other several edible mushrooms under various pHs. The potency of proteolytic enzyme of Neungee was same as the digestive drugs containing protease. So the proteolytic activity of the enzyme was increased in neutral or weak alkaline pH, whose characteristics would be alkaline protease. The specific activity of the purified enzyme obtained by using Tris acryl CM-cellulose ion exchange increased 20 times as compared with that of the crude extract. The proteolytic enzyme was stable at room temperature, but decomposition was fast when incubated at higher temperature more than $40^{\circ}C$. The half life of the enzyme was longest in neutral pH and rate constant was increased in acidic or alkaline solution.

• International Commerce and Information Review
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• v.12 no.4
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• pp.171-192
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• 2010

In general, a stock index and its individual stocks are assumed to follow a random walk. A stock index is an important source of information and one that is seen by people everyday, regardless of their investment intentions. This paper examines the correlation between the KOSPI-the index that best reflects the Korean stock market and the macro - economic variables that have been found to influence the index by previous studies. The sample period considers the years after 2000 when the Korean stock market matured as restrictions on foreign investors were removed. For this purpose, a Vector Error Correction Model (VECM) and KOSPI equation with a general pacific approach were used. This paper aims at verifying the factors that determined the KOSPI after 2000 and at examining whether there was structural change in the investment environment. It also investigates changes in the factors determining the KOSPI's performance as a result of structural changes in the investment environment. The V AR (Vector Autoregressive) model including the nine variables was selected as a baseline model whose stability was tested using the unit root test. The results from the VECM and the structural changes in the investment environment can be summarized by the following Inner story points.

• The Journal of Asian Finance, Economics and Business
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• v.8 no.3
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• pp.1113-1119
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• 2021

This study aims to determine the impact of the news coverage of the COVID-19 pandemic on the composite stocks' movement (IHSG) in Indonesia. This study used secondary data of daily time series with an observation range of March 2020-June 2020. This study used three main variables, namely, COVID-19 news, the daily price of a composite stock market index (IHSG), and interest rate. This study clarifies pandemic news into two forms to facilitate quantitative analysis, namely, good news and bad news. Both pandemic news conditions, which have been clarified, are then processed into the index and reprocessed along with two other variables using vector autoregressive (VAR). The results showed that the good news have a dominant effect on developing the composite stock price index (IHSG) in Indonesia during the COVID-19 pandemic. Although the good news dominates the composite stock price index (IHSG) movement in Indonesia, the bad news must also be anticipated. By implementing a series of macroeconomic policies that follow the conditions of the composite stock price index (IHSG) movements on the stock exchange floor, the bad news response can decrease the potential for a decline in investor confidence, so that the financial system's macroeconomic stability is maintained.

• Journal of the Korean Society of Industry Convergence
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• v.25 no.1
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• pp.131-139
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• 2022

The exchange of goods over the sea is a situation in which the amount of trade between countries is gradually increasing. In order to maintain the optimal operating condition, the ship maintains stability and optimal operating conditions by inserting or withdrawing ballast water from the ballast tank according to the loading condition of cargo capacity is also increasing. Control valves play an important role in controlling fluid flow in these pipes. When the flow rate is controlled using a control valve, problems such as cavitation, flashing, and suffocating flow may occur due to high differential pressure, and in particular, damage to valves and pipes due to cavitation is a major problem. Therefore, in this study, the cavitation phenomenon is reduced by installing orifices at the front and rear ends of the high differential pressure control butterfly valve to reduce the sudden pressure drop at the limiting part of the butterfly valve step by step. The flow coefficient according to the shape of the orifice, the degree of cavitation occurrence, and the correlation were analyzed using a CFD(Cumputational Fluid Dynamics), and an optimal orifice design for reducing cavitation is derived.

• Korean Chemical Engineering Research
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• v.60 no.1
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• pp.7-11
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• 2022

In the membrane forming process of a proton exchange membrane fuel cell (PEMFC), drying and annealing heat treatment processes are required for performance and durability. In this study, the optimal annealing temperature for improving the durability of the polymer membrane was studied. It was annealed in the temperature range of 125~175 ℃, and thermal stability and hydrogen permeability were measured as basic data of durability at each annealing temperature. The electrochemical durability was analyzed by Fenton reaction and open circuit voltage (OCV) holding. The annealing temperature of 165 ℃ was the optimal temperature in terms of thermal stability and hydrogen permeability. In the Fenton reaction, the fluorine emission rate of the membrane annealed at 165 ℃ was the lowest, and the lifespan of the membrane annealed at 165 ℃ was the longest in the OCV holding experiment, confirming that 165 ℃ was the optimal temperature for the durability of the polymer membrane.

• Journal of Fisheries and Marine Sciences Education
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• v.20 no.1
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• pp.135-145
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• 2008

Biogenic amines are naturally occurring anti-nutrition factors. They are causative agents in food poising episodes and act as catalysts to allergic reactions. The most commonly occurring biogenic amines in foods are: Histamine, tyramine, putrescine, cadaverine, tryptamine, ${\beta}$-phenylethylamine, spermine, spermidine and agmatine. The objective of this study was to identify changes and content levels of specific biogenic amines at selected storage temperatures $20{^{\circ}C}$, $4{^{\circ}C}$, and $-25{^{\circ}C}$, respectively. This study will focus on histamine, cadaverine, and putrescine concentrations in the following dark-fleshed fishes: Mackerel (Scomber japonicus), Horse Mackerel (Trachurus japonicus), Mackerel Pike (Cololabis saira), and Spanish Mackerel (Scomberomorus niphonius). Biogenic amines were determined using a method based on an extraction procedure described in the derivatisation and HPLC(High Performance Liquid Chromatography). The the recovery rate of individual amines was higher than those found in ion exchange chromatography. The results from the dark fleshed fish stability trial showed that high content of histamine (cadaverine and putrescine) were produced within a short period of time at $20{^{\circ}C}$. Fish stored at lower temperatures $4{^{\circ}C}$, showed lower content of biogenic amines. At $-25{^{\circ}C}$ the production of histamine, cadaverine and putrescine did not initiate until after day 100. All fish recorded the content of histamine below 1 mg/kg with the exception of the Horse Mackerel.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.40 no.9
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• pp.702-713
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• 2003

The importance of protection for data and information is increasing by the rapid development of information communication and network. And the concern for protecting private information is also growing due to the increasing demand for lots of services by users. Asymmetric cryptosystem is the mainstream in encryption system rather than symmetric cryptosystem by above reasons. But asymmetric cryptosystem is restricted in applying fields by the reason it takes more times to process than symmetric cryptosystem. In this paper, encryption system which executes authentication works of asymmetric cryptosystem by means of symmetric cryptosystem. The proposed cryptosystem uses an algorithms combines that combines block cipherment with stream cipherment and has a high stability in aspect of secret rate by means of transition of key sequence according to the information of plaintext while symmetric/asymmetric cryptosystem conducts encipherment/deciphermeent using a fixed key. Consequently, it is very difficult to crack although unauthenticator acquires the key information. So, the proposed encryption system which has a certification function of asymmetric cryptosystem and a processing time equivalent to symmetric cryptosystems will be highly useful to authorize data or exchange important information.

• Biotechnology and Bioprocess Engineering:BBE
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• v.5 no.3
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• pp.174-180
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• 2000

Cyclodextrin glucanotransferase (CGTasa) from Thermoanaerobacter sp. was adsorbed on the ion exchange resin Amberlite IRA-900. The optimum conditions for the immobilization of the CGTase were pH6.0 and 600 U CGTase/g resin, and the maximum yield of immobilization was around 63% on the basis of amount ratio of the adsorbed enzyme to intial amount in the solution. Immobilixation of CGTase shifted the optimum temperature for the enzyme to peoduce transglycosylated xylitol from 7$0^{\circ}C$ to 9$0^{\circ}C$ and improved the thermal stability of immobilized CGTase, especially after the addition of soluble starch and calcium ions. Transglycosylated xylitol was continuoncly produced using immobilized CGTase in the column type packed bed reactor, and the operating conditions for maximum yield were 10%(w/v) dextrin (13 of the dextrose equivalent) as the glycosyl donor, 10%(w/v) dextrin (13 of the dextrose equivalent) as the glycosyl donor, 10%(w/v) xylitor as the glycosyl acceptor, 20mL/h of medium fiow rate, and 6$0^{\circ}C$. The maximum yield of transglycosylated xylitol and productivity were 25% and 7.82 g.L-1.h-1, respectively. The half-life of the immobilized CGTase in a column type packed bed reactor was longer than 30 days.

• Transactions of the Korean Society of Automotive Engineers
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• v.16 no.5
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• pp.37-43
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• 2008

The durability test of turbo-blower for PEM fuel cell is very important process of BOP development. It is a major barrier to the commercialization of these systems for stationary and transportation power applications. Commercial viability depends on improving the durability of the air supply system to increase the reliability and to reduce the lifetime cost. In this study, turbo-blower supported by oil-free bearing is introduced as the air supply system used by 80kW proton exchange membrane fuel systems. The turbo-blower is a turbo machine which operates at high speed, so air foil bearings suit their purpose as bearing elements. The impeller of blower was adopted mixed type of centrifugal and axial. So, it has several advantages for variable operating condition. The turbo-blower test results show maximum parasitic power levels below 1.67kW with the 30,000 rpm rotating speed, the flow rate of air has maximum 163SCFM(@PR1.1). For proper application of FCV, these have to durability test. This paper describes the experiment for confirming endurance and stability of the turbo-blower for 500 hours.