• 한국산업보건학회지
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• 제26권3호
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• pp.307-316
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• 2016

Objectives: In general, NIOSH method 5506 is most widely used for the occupational exposure measurement of PAHs, but 2-4 ring PAHs have poor desorption efficiency, especially for a filter. The purpose of this study was to determine a method to increase the desorption efficiency of 16-PAHs using an ultrasonic extraction procedure. Methods: Test samples prepared spiked XAD-2 tubes and PTFE filters in the range of $0.01-1.0{\mu}g/mL$ for desorption efficiency study. Four different extraction solvents, acetonitrile, acetone, tetrahydrofuran and dichloromethane, were tested in order to select the most suitable solvent for the extraction of the 16 PAHs. The addition of dimethyl sulfoxide and sonication time were considered in order to determine the method with the highest extraction efficiency. All samples were made in three sets and analysis was replicated seven times by HPLC. Results: Acetonitrile and acetone were the optimized as an extraction solvent and desorption efficiency of 2-ring PAHs such as naphthalene, acenaphthylene were increased 3~19% with dimethyl sulfoxide for XAD-2. Acetone was the best extraction solvent for PTFE filter and the desorption efficiency was increased 3~13% for 2- to 4-ring PAHs. The optimum sonication time was 60 minutes and desorption efficiency increased with extraction time. Conclusions: As a result, the best extraction solvent was acetone with dimethyl sulfoxide for ultrasonic extraction procedure and the desorption efficiency of this method was better than NIOSH 5506's. This study could be applied as a method for occupational exposure measurement of PAHs.

• Journal of East Asia Management
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• 제3권1호
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• pp.11-23
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• 2022

Under the circumstances of China's slower economic growth, the first document ofthe central committee of the CPC continue to focus on "three agricultures" problems, agriculture play a basic role on China's economic. Since 2007, the first document directly stresses the important role of agricultural and fisheries every year. Central Government Working Report of 2015 also stresses that under the new normal of economy, it is important to improve quality and efficiency of agriculture. Agricultural focus going forward will be on improving capacity of competitiveness, innovation and sustainable development.The fishery as an important part of agriculture plays a vital role in the protection of national food security, the prosperity of the rural economy and the optimization of national food structure. However, the situation faced on accelerating the speed of Chinese fisheries is still grim. As an important fishery breeding city in my country, Weihai has achieved remarkable results in the development of fisheries. Based on the input-output indicators of Weihai City from 2010 to 2020, this article uses the DEA model method to conduct a comprehensive analysis of the factors affecting the fishery production efficiency in Weihai City. This paper calculates the two stages of comprehensive efficiency, pure technical efficiency and scale efficiency, and comprehensive compares the two stages. The research results show that: From 2010 to 2020, the average comprehensive technical efficiency of Weihai fishery was 0.928, the average scale efficiency was 0.963, and the average pure technical efficiency was 0.963. The comprehensive technical efficiency of Weihai fishery production showed an upward and downward trend, the pure technical efficiency showed a downward and then upward trend, and the pure technical efficiency showed a fluctuating trend.

• 한국경영과학회지
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• 제41권1호
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• pp.127-143
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• 2016

This study applied DEA analysis to measure the relative efficiency of 35 companies that produce automobile body components. First, the input and output, the improvement target value of the calculated variables, and the reference group for benchmarking for inefficient groups to become efficient groups were established through DEA analysis. In addition, whether inefficiency was due to technical inefficiency or size was analyzed in connection with the cases of the actual companies through the measurement of scale efficiency. Second, a route for efficiency improvement was derived through DEA-Tier analysis by defining the possible group for benchmarking in actuality within the production industry of automobile body components where the primary cooperative company belonged. Third, the financial variables that generate the difference between efficient and inefficient groups were derived through logistic regression analysis. Financial strategies that determine the direction the indices should be improved to allow the inefficient group to become an efficient one were recommended. This research is expected to provide diagnostic methods for management efficiency and the direction of improvement to enhance the management efficiency of automotive parts makers by identifying the causes of the inefficiency of domestic automotive parts makers empirically. The study also provides financial strategies together with the target values of efficiency improvement for each individual company.

• 한국항해항만학회:학술대회논문집
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• 한국항해항만학회 2004년도 춘계학술대회 논문집
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• pp.351-356
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• 2004

부산항은 동북아시아의 급속한 성장과 더불어 지속적인 성장을 해오고 있으며, 향후 이러한 지속적인 성장을 유지하기 위해 정부의 집중 투자 및 정책 지원이 이루어지고 있다. 본 연구는 부산항을 포함한 세계 주요 컨테이너 항만들의 효율성을 DEA(Data Envelopment Analysis)모형을 통해 상대적으로 분석함으로써, 부산항의 현재 위치와 더 효율적인 항만이 되기 위해 Benchmarking 해야할 대상을 구체화 한 것이다. 또한, 본 연구에서는 일정시점의 효율성 분석이 아닌 1995년∼2001년까지 7개년 동안의 효율성을 시계열적으로 분석함으로써 각 항만의 효율성 변화를 살펴볼 것이며 이를 통해서 보다 유효한 효율성 분석 결과를 제시하고자 한다.

• International Journal of Internet, Broadcasting and Communication
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• 제16권1호
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• pp.287-296
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• 2024

Artificial intelligence (AI), the Internet of Things (IoT), and Big Data are playing important roles in improving or upgrading energy efficiency. Furthermore, their roles in energy efficiency are expected to become more and more essential. This study conducted a bibliometric comparative analysis on the features in the articles on the AI, the IoT, and the Big Data in energy efficiency by using the Web of Science database and compared the features in their trends in article publications, citations, countries, research areas, journals, and funding agencies from 2012 to 2022. This study attempted to make significant contributions by shedding new light on the following features. Among the AI, the IoT, and the Big Data in energy efficiency, the most articles were published and the most article citations were received in the AI in energy efficiency. China was found out to be the most leading country. Engineering and computer science were revealed to be the first research area. IEEE Access and IEEE Internet of Things were ranked with first journal. National Natural Science Foundation of China was the first research funding agency concerning the articles published in the AI, the IoT, and the Big Data in energy efficiency from 2012 to 2022.

• 한국물환경학회지
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• 제26권3호
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• pp.399-405
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• 2010

In order to quantify removal efficiency of Cryptosporidium in water treatment process and evaluate factors influencing removal efficiency of Cryptosporidium in each step of water treatment process, large pilot plant system ($100m^3/day$) and Cryptracer, surrogate of Cryptosporidium, were used. The removal efficiency of Cryptracer was around 0.8~1 log in coagulation process and 3.3~4.8 log in sand filtration process under ordinary environmental conditions. Factors influenced removal efficiency of Cryptracer were high fluctuate turbidity and water temperature. High fluctuate turbidity made difficult to adjust optimum PAC concentration, caused to drop removal efficiency of coagulation process (0.5 log). Inadequate coagulation process influenced to sand filtration process (2.1 log), caused to decline of removal efficiency in the whole process (2.6 log). Low temperature below $2^{\circ}C$ also influenced coagulation process (0.6 log). Therefore, It is shown that careful attention in the control of Cryptosporidium is needed in flood period, when high fluctuate turbidity would be, and winter period of low temperature.

• 한국자동차공학회논문집
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• 제19권5호
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• pp.58-66
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• 2011

A 2-loop waste heat recovery system with Rankine steam cycles for the improvement of fuel efficiency of gasoline vehicles has been investigated. A high temperature loop(HT loop) is a system to recover the waste heat from the exhaust gas, a low temperature loop(LT loop) is for heat recovery from the engine coolant cold relatively. This paper has dealt with a layout of a LT loop system, the review of the working fluids, and the design of the cycle. The design point and the target heat recovery of the LT boiler, a core part of a LT loop, has been presented and analytically investigated. Considering the characteristics of the cycle, the basic concept of the LT boiler has been determined as a shell-and tube type counterflow heat exchanger, the performance characteristics for various design parameters were investigated.

• 한국가스학회지
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• 제19권6호
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• pp.40-46
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• 2015

이론공연비방식 엔진은 삼원촉매를 이용하여 유해배기가스를 매우 효과적으로 저감시킬 수 있는 장점을 가지고 있다. 삼원촉매는 높은 정화효율을 보이는 공연비범위가 좁기 때문에 엔진에서의 공연비 제어가 매우 중요하다. 본 연구에서는 삼원촉매 성능을 평가하기 위하여 다양한 운전영역에서 삼원촉매의 전환효율을 비교 분석하였다. 최적의 전환효율을 보이는 당량비를 확인하기 위하여 당량비 제어값 변화에 의한 전환효율을 살펴보았다. 실험결과 당량비 제어를 통하여 각 운전조건에서 NMHC, CH4, CO 및 NOx의 전환효율이 95%이상 나타내는 최적 운전조건을 찾을 수 있었다. 동등한 배기가스 온도 조건에서는 출력이 증가할수록 최적당량비가 선형적으로 증가하는 경향을 보였다.

• 한국수소및신에너지학회논문집
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• 제17권4호
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• pp.409-417
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• 2006

The characteristics of hydrogen-oxygen mixture gas generation stack was experimentally studied in terms of efficiency. For this purpose, the mixture gas generation stack was fabricated by connecting 7 cells in series following the Tero Ranta report. In order to avoid the instrument inaccuracy, all measuring equipments were re-tested and calibrated by Korea Laboratory Accreditation Scheme (KOLAS) certified laboratories. Since the amount of produced gas is most crucial in determining the efficiency, two gas collecting methods such as bottle trap method and wet gas meter method were adopted. From the experimental results, it was found that both KOH fume and steam evaporated along with hydrogen-oxygen mixture gas, and these by-product gases could cause the misestimation of the stack efficiency. The current, voltage, and energy efficiencies of the hydrogen-oxygen mixture gas generation stack was evaluated based upon the stack efficiency calculation method summarized in this work.

• ETRI Journal
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• 제43권6호
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• pp.1093-1102
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• 2021

Microdisplays based on organic light-emitting diodes (OLEDs) have a small form factor, and this can be a great advantage when applied to augmented reality and virtual reality devices. In addition, a high-resolution microdisplay of 3000 ppi or more can be achieved when applying a white OLED structure and a color filter. However, low luminance is the weakness of an OLED-based microdisplay as compared with other microdisplay technologies. By applying a tandem structure consisting of two separate emission layers, the efficiency of the OLED device is increased, and higher luminance can be achieved. The efficiency and white spectrum of the OLED device are affected by the position of the emitting layer in the tandem structure and calculated via optical simulation. Each white OLED device with optimized efficiency is fabricated according to the position of the emitting layer, and red, green, and blue spectrum and efficiency are confirmed after passing through color filters. The optimized white OLED device with color filters reaches 97.8% of the National Television Standards Committee standard.