• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.53 no.2
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• pp.169-176
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• 2017

Tuna purse seine fishery in the western and central Pacific Ocean (WCPO) has been rapidly developed since early 1980s due to massive investment of major distant water fishing nations, and catch by purse seine fishery operating in the WCPO accounts for nearly half of the world's tuna total catch. As fishing efficiency is reflected by not only improving of individual vessel's capacity but also increasing number of active vessel, it is essential to understand vessel capacity for reliable assessment result on how fishery affects stock status of target species. In this study, fishing efficiency was analyzed by main factors which are representative of vessel capacity using fishing data and vessel information related to Korean tuna purse seine fishery operating in the western and central Pacific Ocean from 1992 to 2014. It showed that fishing efficiency of vessel tends to be higher when having larger vessel tonnage, higher engine power, lower vessel age and larger length of vessel. As for fishing efficiency by set type, CPUE of associated set with floating objects was generally higher than that of free school set, and CPUE of free school set seemed to have a greater effect on engine power and vessel age compared to other factors.

• Korean journal of food and cookery science
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• v.23 no.2 s.98
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• pp.270-279
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• 2007

The purposes of this study were to analyze the profitability of audited restaurant franchise firms and to investigate the financial variables affecting profitability. This study decomposed profit variation into the three main factors comprising the Du Pont Identity (operating efficiency, asset use efficiency and financial leverage). The operating efficiency of restaurant franchise firms was on the rise until 2004, but dropped dramatically in 2005. Especially, the profit margin dropped from 13.46% in 2004 to 6.54% in 2005. The asset use efficiency has been decreasing since 2003. The total asset turnover ratio, which can be indicative of over-investment, dropped from 1.55 in 2003 to 1.50 in 2005. The financial leverage remained stable after 2002. There were major differences in debt accumulation among the firms, and the current level of debt was thought to be higher in the restaurant industry than in other industries. Based on the results of a multiple regression analysis, we concluded that the factors affecting ROE were the debt-equity ratio, total asset turnover and the size of the firm. The debt-equity ratio and total asset turnover had a significantly positive effect on ROE, while the firm size had a significantly negative effect on ROE. However, the current ratio and sales growth rate were not significant. The finding that firm size and profitability were negatively related implied that restaurant franchise firms should pursue qualitative growth rather than quantitative growth. There was no major difference in profitability between domestic brands and foreign brands. However, the domestic brand was more efficient in terms of asset usage than the foreign brand.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.17 no.4 s.107
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• pp.317-323
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• 2006

The conventional Wheeler cap method can extract the reliable efficiency of the antenna when the antenna operates as a simple series or parallel RLC circuit model. This method, however, may give an unreliable efficiency when the antenna under test has a complicated operating principle. In this paper, we revisit the conventional Wheeler cap method and propose a modified Wheeler cap method basedon the high-order circuit model. The proposed method can provide an accurate efficiency even for the antenna with a more complicated operating principle. Then we calculate efficiencies of other antennas with different operating principles and compare the results with the simulations.

• Journal of the Korean Society of Marine Environment & Safety
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• v.23 no.7
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• pp.965-971
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• 2017

The primary objective of this study was to assess the energy efficiency performance of an optimized hull form capable of saving energy based on existing vessels. The bow shape of existing vessels was investigated, giving consideration to design draft and speed. Resistance performances were also assessed for existing vessels according to operating conditions. Commercial CFD codes and model test materials were used to assess effective power. An optimized hull form with minimum resistance was selected given real operating conditions. The effective horsepower of existing and optimized vessels was estimated at three speeds. Resistance performance for an optimized vessel showed a 6 % improvement in effective horsepower at design speed (12 knots) compared to existing vessels. Quasi-propulsive efficiency employed experimental data, while energy efficiency performance was analyzed based on operating days, bunker fuel oil C cost, daily fuel oil consumption and specific fuel oil consumption. Energy efficiency performance for an optimized vessel showed a gain of 30 million won per year in reduced costs at design speed (12 knots) compared to existing vessels.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.25 no.2
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• pp.61-69
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• 1989

Mackerel purse seine fishery operating in the sea area of Cheju and Tsushima is one of the most important fishery in Korean off shore fishery, which a fishing fleet are generally composed with one purse seiner, two light ships and three or four fish carriers. In this study, purse seiners are classified in to four classes in term of their gross tonnage : A class(80-100tons), B class(100-120tons), C class(130-140tons), and D class(140-150tons). Operating sea area are divided into five sectors including east and west sea area of Tsushima Island, coastal sea area of Cheju Island and south and west sea area of Cheju Island. The performance of the purse seiner, the fishing efficiency, the dimension of fishing gear and variation of CPUE in each operating sea area are summarized as follows: 1. The relationship between a gross tonnage x and net area of purse seine y of a purse seiner can be expressed as : y=538.8x+99657.3 2. The index of seasonal variation of CPUE from May to October is lower than the standard value, whereas index from November to April is higher. 3. The power factor of fishing efficiency by classes of boat-size shows significant differences with 1% level in each operating sea area. 4. The net efficiency of purse seiner by classes of boat-sea shows that B and C classes are higher than A and D classes.

• Journal of Environmental Health Sciences
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• v.30 no.3
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• pp.221-229
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• 2004

We estimated decreasing rate of indoor air pollutants which are PM10 and $NO_2$ by the air cleaner in indoor environment. This study respectively examined concentration of PM10 and $NO_2$ two times in 34 sites located in Seoul and Kyung-gi Do from April to September in 2003. Sectional period was respectively divided for operating the air cleaner and non-operating the air cleaner. Moreover, questionnaire was executed to grasp physical characteristic of objective building and residential characteristic of residents by using method of self-entry. There was a trend that concentration of PM10 and $NO_2$ separated number of residents during operating period respectively decreased among indoor air. According to the existence of smoker in indoor, both concentration of PM10 and $NO_2$ during operating period decreased in each case, and according to existence of pets, both cases decreased concentration of pollutants by operating the air cleaner. We used Monte-Calro simulation to remove uncertainty and identify efficiency of eliminated pollutants such as PM10 and $NO_2$ by the air cleaner. Average efficiency of removal for PM10 and $NO_2$ were 61.84${\pm}$23.04% and 48.67${\pm}$18.03% respectively.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.56 no.2
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• pp.74-82
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• 2007

Interior permanent magnet synchronous motor(IPMSM) has become a popular choice in electric vehicle applications, due to their excellent power to weight ratio. This paper proposes efficiency optimization control of IPMSM drive using adaptive fuzzy learning control fuzzy neural network (AFLC-FNN) controller. In order to maximize the efficiency in such applications, this paper proposes the optimal control method of the armature current. The controllable electrical loss which consists of the copper loss and the iron loss can be minimized by the optimal control of the armature current. The minimization of loss is possible to realize efficiency optimization control for the proposed IPMSM. The optimal current can be decided according to the operating speed and the load conditions. This paper considers the design and implementation of novel technique of high performance speed control for IPMSM using AFLC-FNN controller. Also, this paper proposes speed control of IPMSM using AFLC-FNN and estimation of speed using ANN controller. The back propagation neural network technique is used to provide a real time adaptive estimation of the motor speed. The proposed control algorithm is applied to IPMSM drive system controlled AFLC-FNN controller, the operating characteristics controlled by efficiency optimization control are examined in detail.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.33 no.12
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• pp.952-960
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• 2009

Selective Catalytic Reduction (SCR) system is a high-effective NOx reduction technology in diesel engines. As the emission standard of diesel engines is more stringent, vehicle manufactures makes efforts on emission technologies. This paper discusses the performance of Urea-SCR system according to the engine operating conditions in a passenger diesel engine. Engine test results in this paper show that it is important to consider the catalyst temperature and space velocity to obtain high NOx conversion efficiency. In condition of high catalyst temperature, over 90% NOx conversion efficiency is indicated. However, when catalyst temperature is low, NOx conversion efficiency was decreased. Also, it was shown that space velocity mainly effects on the DeNOx performance under 220 degree celsius of SCR catalyst temperature. As the urea injection pressure was decreased, NOx conversion efficiency was declined. It is concerned about urea droplet atomization. This work shown in this paper can lead to improved overall NOx conversion efficiency.

• The Journal of Asian Finance, Economics and Business
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• v.8 no.4
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• pp.849-855
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• 2021

The purpose of this study is to analyze and compare Islamic commercial banks and Islamic banking units with the stochastic frontier analysis (SFA) method during 2014-2018. The data in research using Islamic commercial banks and Islamic banking units. There are 10 Islamic commercial banks and 5 Islamic banking units that meet the criteria of purposive sampling. The calculation of efficiency level using the SFA method with the function of production shows that Islamic commercial banks and Islamic banking units always experience an increase in efficiency every year with the average level of efficiency of Islamic commercial banks being 0.43994, while the average rate of efficiency of Islamic banking units is slightly higher at 0.47654. This shows that Islamic banking units are slightly more optimal in generating total financing in the period 2010-2014. The test results using Independent Sample T-Test can be concluded that there is no difference in the efficiency value between Islamic commercial banks and Islamic banking units. Operating costs are not significant and have a positive effect on the total financing; total assets have a significant effect and a positive impact on total financing; labor costs are not significant and have a negative effect on total financing.

• The Journal of Asian Finance, Economics and Business
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• v.9 no.7
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• pp.261-271
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• 2022

Over the last 20 years, the insurance industry in Vietnam has been rapidly growing with an average annual growth rate of 21%, one of the most active markets in Southeast Asia, raising the question of efficiency to managers, investors, and regulators. This article is one of the first research works using Data Envelopment Analysis combined with the Malmquist index over the period from 2016 to 2020 for 37 insurance firms in Vietnam to investigate the efficiency of this sector. The value-added approach is employed with total equity and operating expenses as inputs, finance income, and gross written premium as outputs. The findings reveal that most of Vietnam's insurance companies are operating quite effectively, and the non-life sector is more efficient than the life sector. There is also a regression in efficiency change, while there is a progression in technological change and total factor productivity change during the period examined. The goal of this research is to give a fundamental understanding of the overall efficiency of insurance firms in Vietnam, and help managers, investors, policyholders, and government agencies make better decisions regarding self-assessment, M&A activities, deregulation... Consequently, the insurance sector could improve in terms of efficiency and develop sustainably over time.