• Title, Summary, Keyword: Expected efficiency

Search Result 2,321, Processing Time 0.042 seconds

Influence of Operating Conditions on the Performance of a Oxy-fuel Combustion Reference Cycle (순산소 연소 기본 사이클의 작동조건 변화에 따른 성능해석)

  • Park, Byung-Chul;Sohn, Jeong-Lak;Kim, Tong-Seop;Ahn, Kook-Young;Kang, Shin-Hyoung
    • The KSFM Journal of Fluid Machinery
    • /
    • v.12 no.4
    • /
    • pp.30-36
    • /
    • 2009
  • Recently, there has been growing interest in the oxyfuel combustion cycle since it enables high-purity $CO_2 capture with high$ efficiency. However, the oxyfuel combustion cycle has some important issues regarding to its performance such as the requirement of water recirculation to decrease a turbine inlet temperature and proper combustion to enhance cycle efficiency. Also, Some of water vapour remain not condensed at condenser outlet because cycle working fluid contains non-condensable gas, i.e., $CO_2$. The purpose of the present study is to analyze performance characteristics of the oxyfuel combustion cycle with different turbine inlet temperatures, combustion pressures and condenser pressure. It is expected that increasing the turbine inlet temperature improves cycle efficiency, on the other hand, the combustion pressure has specific value to display highest cycle efficiency. And increasing condensing pressure improves water vapour condensing rate.

A Study of the Effect of Compressor Performance Map on the Efficiency of High-pressure Operating PEMFC Systems in Automotive Applications (압축기 성능 맵이 자동차용 가압형 고분자전해질형 연료전지 시스템 효율에 미치는 영향 연구)

  • Cho, Donghoon;Kim, Han-Sang
    • Transactions of the Korean hydrogen and new energy society
    • /
    • v.23 no.6
    • /
    • pp.604-611
    • /
    • 2012
  • For the commercialization of fuel cell powered vehicle, it is highly important to improve the performance and efficiency of an automotive polymer electrolyte membrane fuel cell (PEMFC) system. The performance and efficiency of PEMFC systems are significantly influenced by their operating conditions. Among these conditions, the system operating pressure is considered as the one of the main factors. In this study, to investigate the effects of operating pressure on the performance and efficiency of automotive PEMFC systems, two types of high-pressure operating PEMFC systems adopting two different compressors (i. e. different performance maps) are modeled by using MATLAB/Simulink environment. The PEMFC system efficiency and parasitic compressor power are mainly analyzed and compared for the two types of high-pressure operating PEMFC systems under the same system net power conditions. It is expected that this kind of study can contribute to provide basic insight into the operating strategies of high-pressure operating PEMFC systems for automotive use.

Analysis of Relative Efficiency of Government Funded Research Institutes Using DEA Model (DEA 모형을 이용한 정부출연연구기관의 상대적 효율성 분석)

  • Nam, In-Suk;Song, Yun-Young;Jeong, Byung-Ho
    • Journal of the Society of Korea Industrial and Systems Engineering
    • /
    • v.31 no.1
    • /
    • pp.1-10
    • /
    • 2008
  • The enormous budget of government and manpower are invested to the government funded institutes every year. The R&D investment focused on input has to be turned toward the investment based on the effectiveness of R&D activities. Measuring the efficiency of research activities is required in order to evaluate the effectiveness of R&D investment in these institutes. The purpose of this paper is to evaluate the relative efficiency of research activities performed in 19 government funded research institutes. CCR/BCC model and DEA/AR model were applied to get the relative efficiency of 19 institutes. Assurance regions for the weight of output attributes were obtained by using the underlined concept of the analytic hierarchy process (AHP). We used input and output data items describing research activity of 19 government funded research institutes. The results of this study are expected to become a basis of the R&D investment decision of the government.

A Thermodynamic Analysis on the Performance with turning Diesel Cycle into Diesel-Atkinson Cycle (디젤기관의 아트킨슨 사이클화에 따른 제반성능의 열역학적 해석)

  • 노기철;정양주;이종태
    • Transactions of the Korean Society of Automotive Engineers
    • /
    • v.12 no.5
    • /
    • pp.1-11
    • /
    • 2004
  • In order to recognize thermal efficiency and power improvement in case that diesel cycle is turned into diesel-atkinson cycle, the fuel-air diesel-atkinson cycle considered gas exchange process is analyzed non-dimensionally and thermodynamically. As a result, in case of diesel-atkinson cycle, as expansion ratio is increased, thermal efficiency and mean effective pressure is increased and it has maximum value at Rec=1. When diesel cycle is turned into diesel-atkinson cycle by late intake valve closing timing, thermal efficiency and power is decreased because of the decline of effective compression ratio and intake airflow, but it could be compensated by increase of compression ratio or super-charged. In case compression ratio is compensated, Rec appears 1 around 100$^{\circ}$ ABDC, and it is expected that thermal efficiency is enhanced by 14.3% compared with conventional diesel cycle. In case compression ratio and intake airflow are compensated simultaneously, super-charged pressure is demanded 2.06bar at Rec=1 and it is more efficient when only compression ratio is compensated in the view point of thermal efficiency.

Catching efficiency of the biodegradable gill net for Pacific herring (Clupea pallasii) (생분해성 청어 (Clupea pallasii) 자망의 어획성능)

  • An, Heui-Chun;Kim, Seong-Hun;Lim, Ji-Hyun;Bae, Jae-Hyun
    • Journal of the Korean Society of Fisheries and Ocean Technology
    • /
    • v.49 no.4
    • /
    • pp.341-351
    • /
    • 2013
  • Physical characteristics of PA (Polyamide) gill net and biodegradable gill net made by PBS (Polybutylene succinate) (mesh size 63mm, mesh thickness number 2, 2.5, 3) were analyzed to investigate catching efficiency of the biodegradable gill net for Pacific herring. Total 11 numbers of catching efficiency tests were carried out using commercial fishing vessel at Imwon port in Kangwon province from May to June 2013. The amount of catches were 1,535.7kg (18 species) through the catching efficiency tests and it is expected that the practicalization of biodegradable gillnet is possible because there is no difference for catches between PA gillnet and PBS gillnet. Catches of herring according to the thickness of net twine was the highest at No.2 and the thicker net twine tends to decrease the catches.

Analyzing the Efficiency of LID Technique for Urban Non-point Source Management - Focused on City of Ulsan in Korea - (저영향개발기법 적용을 통한 비점오염원 저감 및 비용효율 분석에 관한 실증적 연구 - 울산광역시를 대상으로 -)

  • Lim, Yong-Kyun;Jung, Ju-Chul;Shin, Hyun-Suk;Ha, Gyoung-Jun
    • Journal of the Korean Society of Environmental Restoration Technology
    • /
    • v.17 no.2
    • /
    • pp.1-14
    • /
    • 2014
  • The purpose of this study is to identify the efficiency of LID technologies for controlling non-point source pollution from urban areas. The recent technical responses to managing water resource and urban areas according to the influence of climate change is an important national policy, along with green growth. Through various reference studies reasonable ways to consider a wholistic plan on urban-eco-friendly river management, the Low Impact Development (LID) as the adequate river management method is being undertaken in foreign countries to technically apply to urban plans. However, the LID is at the initial stage in Korea, with no specific studies implemented. Thus, this study explored whether LID technologies can be efficient measures to control non-point source pollution on the cost side. Ulsan's Namgu and Bukgu have been chosen as case studies that illustrate the efficiency of the LID technologies. On investigation, if LID technologies are designed properly, the efficiency of them is expected to higher than that of sewage treatment plant.

Case Study for Increasing the Learning Effect In Cyber Lecture (사이버 강좌에서 학습 효과를 높이기 위한 사례 연구)

  • Um, Jong-Seok;Cho, Sae-Hong
    • Journal of Korea Multimedia Society
    • /
    • v.16 no.10
    • /
    • pp.1230-1237
    • /
    • 2013
  • Cyber lectures were expected to replace the traditional classroom lecture, yet they were criticized due to the inefficiency. With educational technology supplemented, cyber lectures have improved their efficiency through the coherence of superior planning ability and improvement in computer and network technology. This paper's purpose is to understand the factors that improve educational efficiency of cyber lectures. Cyber lecture for IT subject for software practice is created to test the educational efficiency as lecture on theories will not distinctively show the lecture efficiency. The survey was conducted to students and statistical analysis was done on collected data to analyze the factors that influence educational efficiency of created lecture.

A Study on the Integration of Framework National Tax Basic Act and Local Tax Basic Act (국세기본법과 지방세기본법의 통합과 체제 개편에 관한 연구)

  • Kim, Woo-Young;Kim, Keum-Young
    • Asia-Pacific Journal of Business
    • /
    • v.9 no.2
    • /
    • pp.75-103
    • /
    • 2018
  • The tax system in Korea is the so-called one-item-one-tax law which has separate tax law for each taxation according to tax law. The common and procedural aspects of these tax laws are the same or similar, but they are separately prescribed by the National Tax Basic Act and the Local Tax Act. These legal systems complicate the tax law and increase the cost of tax cooperation, resulting in tax inefficiency. In this study, the National Tax Act and the laws of the Local Tax Act are integrated and presented. It is proposed that the common provisions should be integrated into a single law and the unique matters should be defined in each of the National Tax Basic Act and Local Tax Basic Act, by comparing and analyzing the provisions of the National Tax Basic Act and the Local Tax Basic Act. The integration of the common elements of the National Tax Basic Act and the Local Tax Act is expected to improve tax efficiency by reducing tax complexity and tax cooperation costs. In addition, the National Tax Act and the Local Tax Act are expected to maintain the characteristics of the National Tax Basic Act and the Local Tax Act when they are specified in the National Tax Basic Act and the Local Tax Basic Act. This study is expected to be a research that can reduce tax inefficiency and help convenience of taxpayer and tax administration.

  • PDF

Analysis on Management Practice of Trust Farming Corporations (농업회사 법인의 경영 실태 분석)

  • Kim, Jeong-Pil;Kim, Jai-Hong
    • Korean Journal of Agricultural Science
    • /
    • v.28 no.2
    • /
    • pp.147-161
    • /
    • 2001
  • Efficiency and competitive power in agribusiness management has became important issue due to the rapid changes in farming environment under new WTO agreement. To increase competitive power, small-sized petty farm should be restructured to be specialized large-scaled farming system. Trust farming corporation(TFC) has been introduced to increase farm productivity and competitive power through large scale farming system and refined management skills. Eventually, TFCs are expected to revitalize rural economy. TFCs are increasing in numbers, but they are unsatisfactory in quality often with insolvent operations. The typical problems with TFCs are internal conflicts among members, lack of management abilities and incentives, inefficiency in machinery use, and insolvent operations. The self effort by members and legal-institutional assistance can alleviate the negative factors against the rational for cooperative management and sustain TFCs. This study identifies the management problems of TFCs. To provide the methods for increasing management efficiency, improving rational management skills, and hence to help revitalizing the rural economy with competitive power, 20 TFCs in Nonsan County is surveyed. The major findings are as follows; 1) According to the survey result of 20 trust farming corporations, investments on the accumulation of knowledges and information, accounting management, machinery management are required due to the present lack of management/accounting ability. There also exist problems associated with revenue sources, labor uses, and public recognition. To increase management efficiency under current situation, corporations should import active business plans with expanding farming execution and off-farm season business. 2) Based on the result of corporations' business analysis, more than 50% of the corporations were not able to provide profit dividends to the members. It suggests that trust farming corporations need appropriate and stable revenue sources to sustain business. It is also required that corporations should reduce their excessive expenditure on fixed assets. 3) Theoretical amounts of consignment fees for tillage operation, planting, and harvesting were found to be 338,874 won, 216,596 won, and 332,318 won, respectively. Although actual levels of fee are 110%~120% of these theoretical levels of consignment fee, corporations' expected fee levels could not be acheived because of competency of consignment market.

  • PDF

Design and Development of Health Screening Data Input Mobile Application Using App-Inventor (앱인벤터를 이용한 건강검진 데이터 입력 모바일 애플리케이션 설계 및 개발)

  • Lee, Hyo-Seung;Oh, Jae-Chul
    • The Journal of the Korea institute of electronic communication sciences
    • /
    • v.13 no.1
    • /
    • pp.193-198
    • /
    • 2018
  • These days, computer system has been introduced for work in most areas, including manufacturing, medical service, education, logistics, and other services. To increase work efficiency, mobile system has been more applied. However, on the basis of Android applications, it is hard for laypersons who have no enough knowledge of Android, or computer team members in general firms to develop mobile App. As a result, work efficiency comes to low. Therefore, this study designed and developed the mobile application for anthropometry data input of medical checkup with the use of App Inventor. As shown in the designed and developed mobile application, it is expected to develop a work process mobile App, it is expected to develop a work process mobile App easily and quickly with the use of App Inventor and to increase work efficiency even though there is not much knowledge of mobile application development.