• Title/Summary/Keyword: System Performance Improvement

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A Study on the Ranking Strategy for the Product Improvement of the K Series Tank using AHP, Scoring Method, and TOPSIS (AHP와 평점법 및 TOPSIS를 활용한 K계열 전차 성능개량 우선순위에 대한 연구)

  • Na, Jae-Hyun;Park, Chan-Hyeon;Kim, Dong-Gil
    • The Journal of the Korea institute of electronic communication sciences
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    • v.16 no.5
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    • pp.899-908
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    • 2021
  • Since the modern weapon system is composed of a complex system, it is quite difficult to derive the priority of performance improvement factors. In addition, research on the method for prioritizing quantitative performance improvement factors considering the opinions of stakeholders is insufficient. In this study, in order to quantitatively derive the priorities of performance improvement factors for K1 tanks and K2 tanks, a survey was conducted with experts with experience in tank development, and the preface data was analyzed using AHP, scoring method, and TOPSIS methods. As a result, priorities were quantitatively derived. The results of this study are expected to be used as decision-making indicators for stakeholders in the future weapon system development and performance improvement stage.

Assessing the Safety Performance of Small-sized Contractors and Improvement Measures (소규모 건설회사의 안전관리 실태 분석 몇 개선방안)

  • Choi, Seung-Mo;Lee, Dong-Eon;Son, Chang-Baek
    • Journal of the Korean Society of Safety
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    • v.23 no.4
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    • pp.53-58
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    • 2008
  • This paper presents the findings obtained from the investigation of fatal disasters occurred by small-sized construction firms which have been accepted as to provide lower safety performance other than large-sized construction enterprises and cause more than half of the safety accidents in average. The study identifies the current status of safety performance provided by the small-sized construction contractors in details, find the issues involved with lack of safety performance, and suggest the improvement measures derived from the findings. A survey questionnaire was administered to the construction contractors, which are listed in the database of Construction Association of Korea as to fall into rank between 501st and 1000th in construction capacity. Safety issues such as the performance of safety management system, safety control structure, safety cost relative to safety control, education devoted to safety improvement, usage of safety garments or individual protective tools, and activities to maintain safety performance on site, etc were investigated from the study.

Performance Analysis of Multi-Carrier CDMA Systems under Indoor Wireless Environment with Impulsive Noise (임펄스성 잡음이 존재하는 실내 무선 환경에서 Multi-Carrier CDMA 시스템의 성능 분석)

  • Lee, Young-Choon;Park, Ki-Sik;Cho, Sung-Joon
    • Journal of Advanced Navigation Technology
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    • v.7 no.1
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    • pp.30-37
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    • 2003
  • In this paper, we have analyzed the BER (Bit Error Rate) performance of MC-CDMA systems under indoor wireless environment with class A impulsive noise suggested by Middleton. For the performance evaluation, we considered from strong to weak impulsive noise characteristics. And we have evaluated the degree of performance improvement by using turbo code as a compensation technique to impulsive noise. From the result of analysis, it is found powerful performance improvement scheme must be adopted in the system under impulsive noise environment, and when turbo code scheme is adopted, system BER performance is improved by the $10^{-2}$. As the impulsive noise characteristics approaches AWGN characteristics, the degree of performance improvement by adopting turbo code become larger.

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Fuzzy Expert PID Control of Magnetic Bearing System (자기베어링 시스템의 퍼지 전문가 PID 제어)

  • Gyeong, Jin-Ho;Kim, Yu-Il;Kim, Jong-Seon;Lee, Hae
    • 연구논문집
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    • s.23
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    • pp.73-80
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    • 1993
  • This study presents an intelligent PID control method based on the fuzzy logic and this method is applied to the active magnetic bearing system. By using an appropriate fuzzy matrix, some changes of values of the three coefficients of the controller are determined during system operation and these lead to the improvement of the transient and steady state behavior of the closed loop system. The presented method is actually a combination of the principles of PID control and fuzzy logic. Since the fuzzy logic using linguistic variables in place of numeric variables has many points of likeness to the human logic, the improvement in performance is notable especially in case of large nonlinearity and uncertainty such as the controller start and the excessive mass unbalance. A set of simulation and experimental results illustrate and considerable improvement in the control performance including small overshoot and small transient currents in magnet coils, while maintaining the overal static and dynamic characteristics near the equilibrium position.

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Flow Control in the Vacuum-Ejector System (진공 이젝터 시스템의 유동 컨트롤)

  • Lijo, Vincent;Kim, Heuy-Dong
    • Proceedings of the Korean Society of Propulsion Engineers Conference
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    • 2010.05a
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    • pp.321-325
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    • 2010
  • Supersonic ejectors are simple mechanical components, which generally perform mixing and/or recompression of two fluid streams. Ejectors have found many applications in engineering. In aerospace engineering, they are used for altitude testing of a propulsion system by reducing the pressure of a test chamber. It is composed of three major sections: a vacuum test chamber, a propulsive nozzle, and a supersonic exhaust diffuser. This paper aims at the improvement of ejector-diffuser performance by focusing attention on reducing exhaust back flow into the test chamber, since alteration of the backflow or recirculation pattern appears as one of the potential means of significantly improving low supersonic ejector-diffuser performance. The simplest backflow-reduction device was an orifice plate at the duct inlet, which would pass the jet and entrained fluid but impede the movement of fluid upstream along the wall. Results clearly showed that the performance of ejector-diffuser system was improved for certain a range of system pressure ratios, whereas the orifice plate was detrimental to the ejector performance for higher pressure ratios. It is also found that there is no change in the performance of diffuser with orifice at its inlet, in terms of its pressure recovery. Hence an appropriately sized orifice system should produce considerable improvement in the ejector-diffuser performance in the intended range of pressure ratios.

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Numerical Investigation of the Effects of an Orifice Inlet on the Performance of an Ejector (Orifice Inlet효과에 의한 이젝터 성능에 관한 수치해석적 연구)

  • Lijo, Vincent;Kim, Heuy-Dong;Setoguchi, Toshiaki
    • Proceedings of the Korean Society of Propulsion Engineers Conference
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    • 2009.11a
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    • pp.318-322
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    • 2009
  • Supersonic ejectors are simple mechanical components, which generally perform mixing and/or recompression of two fluid streams. Ejectors have found many applications in engineering. In aerospace engineering, they are used for altitude testing of a propulsion system by reducing the pressure of a test chamber. It is composed of three major sections: a vacuum test chamber, a propulsive nozzle, and a supersonic exhaust diffuser. This paper aims at the improvement of ejector-diffuser performance by focusing attention on reducing exhaust back flow into the test chamber, since alteration of the backflow or recirculation pattern appears as one of the potential means of significantly improving low supersonic ejector-diffuser performance. The simplest backflow-reduction device was an orifice plate at the duct inlet, which would pass the jet and entrained fluid but impede the movement of fluid upstream along the wall. Results clearly showed that the performance of ejector-diffuser system was improved for certain a range of system pressure ratios, where as there was no appreciable transition in the performance for lower pressure ratios and the orifice plate was detrimental to the ejector performance for higher pressure ratios. It is found that an appropriately sized orifice system should produce considerable improvement in the ejector-diffuser performance in the intended range of pressure ratios.

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A Study on Application of Shaft-box Type Double Skin to Apartment Building (공동주택에 대한 Shaft Box형 이중외피의 적용에 관한 연구)

  • Roh, Ji Wooung
    • KIEAE Journal
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    • v.13 no.1
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    • pp.75-81
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    • 2013
  • The balcony of our apartment building consists of unique construction similar to double skin. It is announced broadly that double skin is very effective system in improvement of natural ventilation and indoor thermal environment, and outdoor sound protection. So, for the improvement of indoor climate and energy saving, many peoples studied about environmental performance of our balcony construction. This study focus on shaft box facade, special form of box window construction. It consists of a system of box window with continuous vertical shafts that extend over a number of stories to create a stack effect. Proto-type was decided by analyzing various types of exiting apartments. Shaft box type balcony was created by setting up shaft space at a part of balcony. Air flow and contribution of air temperature were simulated, performance of shaft box type balcony was compared with existing balcony. Finally, we confirmed that shaft box type balcony has many possibility for improvement of indoor environment.

Performance Improvement of DSRC unit for Automatic Gate Clearance System (자동게이트통관시스템용 DSRC 단말기의 성능 개선)

  • 박상완;정봉식
    • Proceedings of the IEEK Conference
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    • 2002.06a
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    • pp.187-190
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    • 2002
  • In this paper, we deal with performance improvement of OBE for automatic gate clearance system by using DSRC network of 5.8GHz ISM band. A data format is improved to represent Rx and Tx information which is need to perform clearance at the gate of container terminal. An error message caused by data discordance is added to Previous data format. A graphic LCD monitor is used to control a character font and use Korean.

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Evaluation Method for Measurement System and Process Capability Using Gage R&R and Performance Indices (게이지 R&R과 성능지수를 이용한 측정시스템과 공정능력 평가 방법)

  • Ju, Youngdon;Lee, Dongju
    • Journal of Korean Society of Industrial and Systems Engineering
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    • v.42 no.2
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    • pp.78-85
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    • 2019
  • High variance observed in the measurement system can cause high process variation that can affect process capability badly. Therefore, measurement system analysis is closely related to process capability analysis. Generally, the evaluation for measurement system and process variance is performed separately in the industry. That is, the measurement system analysis is implemented before process monitoring, process capability and process performance analysis even though these analyses are closely related. This paper presents the effective concurrent evaluation procedure for measurement system analysis and process capability analysis using the table that contains Process Performance (Pp), Gage Repeatability & Reproducibility (%R&R) and Number of Distinct Categories (NDC). Furthermore, the long-term process capability index (Pp), which takes into account both gage variance and process variance, is used instead of the short-term process capability (Cp) considering only process variance. The long-term capability index can reflect well the relationship between the measurement system and process capability. The quality measurement and improvement guidelines by region scale are also described in detail. In conclusion, this research proposes the procedure that can execute the measurement system analysis and process capability analysis at the same time. The proposed procedure can contribute to reduction of the measurement staff's effort and to improvement of accurate evaluation.

The Analysis of Priority on Improvement of IT Systems for B2B Collaboration of Small and Medium-Sized Enterprise Using the Performance Model (Performance Model을 이용한 중소기업의 대기업과의 협업을 위한 IT시스템 개선의 우선순위 도출)

  • Hong, Jung-Wan;Jeon, Dong-Uk;Lee, Hyo-Sook
    • IE interfaces
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    • v.25 no.1
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    • pp.64-70
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    • 2012
  • In modern society, the importance of inter-enterprise collaboration on supply chain is more emphasizing, depending on the industrial structure is going advanced. Therefore, the studies for advancement of inter-enterprise collaboration are taking, and especially the studies about how IT systems affect those advancement are taking. However, there are a shortage of recognition to each IT systems on B2B collaboration, additionally there is not much study of its application. In this study, we analyze the Performance Model relationship between the level and the importance of IT system for B2B collaboration in small and medium-sized enterprise, and draw a priority order for improvement of IT systems for its effective practical use.