• Title/Summary/Keyword: Decrease Work Efficiency

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An Analysis Study for Thermal Design of ISG (Integrated Starter & Generator) for Hybrid Electric Vehicle (하이브리드 차량용 ISG(Integrated Starter Generator)의 방열 설계를 위한 해석적 연구)

  • Kim, Dae Geon;Kim, Sung Chul
    • Transactions of the Korean Society of Automotive Engineers
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    • v.21 no.4
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    • pp.120-127
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    • 2013
  • Hybrid electric vehicles have applied electric parts for saving fuel consumption and reducing levels of environmental pollution. Electrification of automobiles is indispensable for entering into global market because of enhanced environment restriction. ISG (Integrated Starter & Generator) system is one of main electric parts and can improve fuel efficiency more than other components by using Idle Stop & Go function and regenerative braking system. However, if ISG motor and inverter work under the continuously high load condition, it will make them the decrease of performance and durability. So the ISG motor and inverter need to properly design the cooling system of them. In this study, we suggested the enhancement points by modifying the thermal design of ISG motor and then confirmed the improvement of the cooling performance.

Development of Multi-Porous Diamond Wheel for Smooth and Mirror Finishing of Die Materials (금형재료의 정밀연삭을 위한 다기공 다이아몬드 숫돌의 개발)

  • 허성중
    • Journal of the Korean Professional Engineers Association
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    • v.30 no.6
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    • pp.144-152
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    • 1997
  • Development of diamond wheel with fine grains and multi-pore structures were newely attempted to be studied in this paper. Wheels, that are employed for the smooth and mirrow finishing of die materials such as tungsten carbide alloy using tool and die materials, must have both performances to remove tool marks efficiently and to contact elastically with curved surfaces. Diamond abrasive grains were bonded firmly by a melamine to prevent the decrease of machining efficiency due to grain sinking within the bond materials. Also, highly foamed structures were developed to increase the flexibility of the wheel, and to induce active self-sharpening by increasing contact pressure between the wheel and work sufaces. In this paper, melamine-bonded diamond wheels are trial manufactured, then the forming method of wheels are explained.

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Distortion of Eelectrical Double Layer in Liquid Filtration by Fibrous Filters

  • Lee, Myong-Hwa;Hirose, Shogo;Otani, Yoshio
    • Particle and aerosol research
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    • v.10 no.3
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    • pp.99-108
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    • 2014
  • Liquid filtration by membrane filters is essential for the preparation of ultrapure water in semiconductor manufacturing processes. The separation of submicrometer particles suspended in ultrapure water with a laminated fibrous membrane filter was studied numerically and experimentally in the present work. We found that an electrical double layer around a single fiber expanded to a large extent at a low ion concentration, as in ultrapure water, and deformed toward the upstream of the fiber with increasing filtration velocity. Since an increase in the electrical double-layer thickness leads to a decrease in the electrical potential gradient, particles with the same polarity as the fiber approach the fiber more easily and are captured at a high filtration velocity. Experimental results also confirmed that the collection efficiency of polystyrene latex(PSL) particles through a PTFE filter became higher as the filtration velocity increased.

Development of diamond wheel for ultra precision and high performance grinding of difficult-to-materials (난삭재의 초정밀.고능률 연삭가공을 위한 다이아몬드숫돌의 개발)

  • Heo, Seong-Jung
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.21 no.12
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    • pp.2172-2178
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    • 1997
  • Development of diamond wheel with fine grains and multi-pore structures were newely attempted. Wheels, that are employed for ultra precision and high performance grinding of difficult-to materials such as tungsten carbide alloy using tool and die materials, must have both performances to remove tool marks efficiently and to contact elastically with curved surfaces. Diamond grains were bonded firmly by a melamine resin to prevent the decrease of machining efficiency due to grain sinking within the bond materials. Also, highly foamed structures were developed to increase the flexibility of the wheel, and to induce active self-sharpening by increasing contact pressure between the wheel and work surfaces. In this paper, melamine-bonded diamond wheels are trial manufactured, then the forming method of wheels are suggested, and the grinding characteristics of wheels are also illustrated.

An Study on Efficiency and Application of Thermal Siphon in the Permafrost (영구동토 지대에서 Thermal Siphon의 효율성 연구)

  • Kang, Jae-Mo;Kim, Hak-Seung
    • Proceedings of the Korean Geotechical Society Conference
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    • 2009.09a
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    • pp.963-966
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    • 2009
  • A Construction of pipe line foundation and railroad, buildings in a permafrost area requires engineering technology of ground stabilization. In the permafrost area, thermal siphons have been used to stabilize foundation by eliminating the heat of ground to the air. the thermal siphon is a passive heat transfer device that operates by convection through vaporization and condensation. The heat transfer from ground to the air is driven by a temperature difference across the unit. A buried part in ground working as vaporizing function and upper part work as condensing. In this study, buried thermal siphon around the pipe lines laid in the Vladivostok site and measuring temperature variation. It is found that the thermal siphons freezing ground faster and decrease temperature variation in winter season.

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A Feature Analysis of Industrial Accidents Using CHAID Algorithm (CHAID 알고리즘을 이용한 산업재해 특성분석)

  • Leem Young-Moon;Hwang Young-Seob
    • Journal of the Korea Safety Management & Science
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    • v.7 no.5
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    • pp.59-67
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    • 2005
  • The main objective of the statistical analysis about industrial accidents is to find out what is the dangerous factor in its own industrial field so that it is possible to prevent or decrease the number of the possible accidents by educating those who work in the fields for safety tools. However, so far, there is no technique of quantitative evaluation on danger. Almost all previous researches as to industrial accidents have only relied on the frequency analysis such as the analysis of the constituent ratio on accidents. As an application of data mining technique, this paper presents analysis on the efficiency of the CHAID algorithm to classify types of industrial accidents data and thereby identifies potential weak points in accident risk grouping.

New Sustain driving Method for the low Power consumption In AC PDP (저전력 구동을 위한 AC PDP의 새로운 서스테인 구동방식)

  • Lee, Ji-Hoon;Lee, Don-Kyu;Yoon, Cho-Rom;Lee, Ho-Jun;Park, Cha-Su
    • Proceedings of the KIEE Conference
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    • 2006.07c
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    • pp.1515-1516
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    • 2006
  • The low luminous efficacy is one of the major demerits of plasma display panel (PDP). In this work we propose the new driving method for high efficiency AC-PDP and analyze its discharge characteristics. The suggested method can control the effective capacitance of panel by external circuit. As a result of the new suggested method, the current becomes less and the discharge time becomes long, because of voltage distribution between panel and auxiliary capacitor. So this method can decrease the power consumption much more than that of the conventional driving method.

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Inverted structure perovskite solar cells: A theoretical study

  • Sahu, Anurag;Dixit, Ambesh
    • Current Applied Physics
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    • v.18 no.12
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    • pp.1583-1591
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    • 2018
  • We analysed perovskite $CH_3NH_3PbI_{3-x}Cl_x$ inverted planer structure solar cell with nickel oxide (NiO) and spiroMeOTAD as hole conductors. This structure is free from electron transport layer. The thickness is optimized for NiO and spiro-MeOTAD hole conducting materials and the devices do not exhibit any significant variation for both hole transport materials. The back metal contact work function is varied for NiO hole conductor and observed that Ni and Co metals may be suitable back contacts for efficient carrier dynamics. The solar photovoltaic response showed a linear decrease in efficiency with increasing temperature. The electron affinity and band gap of transparent conducting oxide and NiO layers are varied to understand their impact on conduction and valence band offsets. A range of suitable band gap and electron affinity values are found essential for efficient device performance.

Comprehensive Analysis and Evaluation of Mobile S-MAC Protocol in Wireless Sensor Network

  • Alanazi, Adwan Alownie
    • International Journal of Computer Science & Network Security
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    • v.22 no.4
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    • pp.358-366
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    • 2022
  • Wireless sensor networks (WSN) are becoming widely used in collecting and sensing information in different fields such as in the medical area, smart phone industry and military environment. The main concern here is reducing the power consumption because it effects in the lifetime of wireless sensor during commutation because it may be work in some environment like sensor in the battlefields where is not easy to change the battery for a node and that may decrease the efficiency of that node and that may affect the network traffic may be interrupted because one or more nodes stop working. In this paper we implement, simulate, and investigate S-MAC protocol with mobility support and show the sequence of events the sender and receiver go through. We tested some parameters and their impacts of on the performance including System throughput, number of packets successfully delivered per second, packet delay, average packet delay before successful transmission.

Performance Analysis of Centrifugal Compressor in Wet Compression (물입자를 분사하는 원심압축기의 성능해석)

  • Kang Jeong-Seek;Cha Bong-Jun;Yang Soo-Seok
    • Proceedings of the Korean Society of Propulsion Engineers Conference
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    • v.y2005m4
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    • pp.237-242
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    • 2005
  • The energy consumed by compressor in gas turbine is equivalent to $30\sim50\%$ of energy produced by turbine and, therefore, research on reducing compression work is important in increasing the efficiency of gas turbine. One of the method to reduce the compression work is to inject small water droplets into the compressor. This method decreases the compression work by decreasing the compressor exit temperature through the evaporation of water. Researches on wet compression, up to now, are focused on thermodynamic analysis of wet compression where the decrease of exit flow temperature and compression work is demonstrated. This paper presents an thermodynamic and aerodynamic analysis of wet compression in centrifugal compressor for microturbine.

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