• 수산해양기술연구
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• 제53권2호
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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.

• 한국식품조리과학회지
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• 제23권2호통권98호
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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.

• 한국전자파학회논문지
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• 제17권4호
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• pp.317-323
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• 2006

기존의 Wheeler cap 방법은 안테나의 등가회로가 간단한 직렬 또는 병렬 RLC 회로로 나타날 경우 동작 주파수 부근에서 안테나의 효율을 정확하게 계산할 수 있지만, 안테나의 등가회로가 복잡한 형태로 나타날 경우에는 적용할 수 없는 단점을 가지고 있다. 본 논문에서는 기존 Wheeler cap 효율 측정 방법의 적용 조건과 그로 인하여 발생되는 문제점을 살펴보고, 고차회로를 기반으로 개선된 Wheeler cap 효율 측정방법을 제안하였다. 제안된 방법은 안테나의 동작원리가 복잡하더라도 넓은 주파수 범위에서 비교적 정확하게 안테나의 효율을 계산할 수 있다. 복잡한 손실구조를 가지는 몇 가지 안테나들의 효율을 개선된 방식을 이용하여 측정하고, 시뮬레이션 결과와 비교 검토하여 제안된 방법을 검증하였다.

• 해양환경안전학회지
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• 제23권7호
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• pp.965-971
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• 2017

본 논문의 주 목적은 기존선형과 저항을 최소화하는 최적선형에 대한 에너지효율 성능을 평가하는 것이다. 설계 흘수와 설계 선속을 고려하여 대상선박의 선수부 형상을 검토하였다. 실제 운항 상태에서 대상선박의 저항성능을 평가하였다. 상용 전산유체역학(CFD) 코드와 수조 모형시험 자료는 유효마력 평가를 위해 사용되었다. 실제 운항 상태를 고려하여 최소저항을 가지는 최적선형을 제시하였다. 기존선형과 최적선형에 대하여 3가지 선속에서 유효마력을 추정하였다. 최적선형의 저항성능은 기존선형과 비교하여 볼 때 설계속도(12노트)에서 약 6 % 향상된 결과를 보여 주었다. 준추진효율 계수(ETAD, ${\eta}_D$)는 모형시험 자료를 활용하였다. 에너지 효율 성능은 년간 운항일수, 벙커C유 가격, 1일 연료사용량 그리고 연료소비계수를 바탕으로 작성되었다. 최적선형의 에너지 효율 성능은 기존선형과 비교하였을 때 12노트에서 연간 약 3천만원 절약된 결과를 보여 주었다.

• 수산해양기술연구
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• 제25권2호
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• pp.61-69
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• 1989

한국 제주도와 대마도 주변해역을 중심으로 고등어와 정어리를 주어획대상으로 선단조업을 하고 있는 건착망어업의 어선의 성능, 어패의 크기, 어획성능, 조업해역별 단위노력당 어획량등을 조업어선의 톤급별로 분석, 검토한 결과는 다음과 같다. 1. 망선의 총톤수(x)와 건착망의 면적(y)간에는 y=538.8x+99657.3의 관계가 있었다. 2. CPUE의 계절변동지수는 11~4월은 기분보다 높고, 5~10월은 낮은 현상을 나타내었다. 3. 각 해역에 있어서 톤급별 어획성능지수는 톤급별, 해역별 CPUE는 1%의 유음수준에서 차가 인정되었다. 4. 톤급별 망어패의 효율은 A와 D급선 보다 B와 C급선이 높은 현상을 나타내었다

• 한국환경보건학회지
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• 제30권3호
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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.

• 전기학회논문지P
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• 제56권2호
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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.

• 대한기계학회논문집B
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• 제33권12호
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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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• 제8권4호
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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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• 제9권7호
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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.