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Microparticle Impact Motion with Adhesion and Frictional Forces (부착력과 마찰력이 개재된 마이크로 입자 충돌 운동)

  • Han, In-Hwan
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.26 no.8
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    • pp.1698-1708
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    • 2002
  • The main topic covered in this paper is that of the impact process, that is, where two bodies come into contact and rebound or stick together. This paper presents how to determine the rebound velocities of a microparticle that approaches a surface with arbitrary initial velocities and relate the impact process to the physical properties of the materials and to the adhesion force. Actual adhesion forces demonstrate a significant amount of energy dissipation in the form of hysteresis, and act generally in a normal to the contact surfaces. Microparticles must also contend with forces tangent to the contact surfaces, namely Coulomb dry friction. The developed model has an algebraic form based on the principle of impulse and momentum and hypothesis of energy dissipation. Finally, several analyses are carried out in order to estimate impact parameters and the developed analytical model is validated using experimental results.

Phytoremediation and Bioremediation of Land Contaminated by Hydrocarbons: Modeling and Field Applications

  • Sung, Kijune;Corapcioglu, M.Yavuz
    • Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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    • 2002.04a
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    • pp.18-21
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    • 2002
  • Phytoremediation which uses plants to enhance the bioremediation through stimulation of microbial activity and root uptake, has been a topic of increasing interest. Mathematical model were developed that can be applied to various bioremediation methods in the unsaturated zone, especially phytoremediation, for simulating the fate and transport of contaminants under field conditions. A 2-year field study was conducted using 72 (1.5m long and 0.1 m diameter) column lysimeters with four treatments: Johnsongrass; wild rye grass; a rotation of Johnsongrass and wild rye grass; and unplanted fallow conditions. The developed model represented the fate and transport of contaminant both in vegetated and unplanted soils satisfactorily for field applications. Parameters related to the contaminant concentration in the water phase were the main parameters determining the contaminant fate in the vadose zone and indicated that the bioavailability can be the most important factor in the success of phytoremediation as well as bioremediation applications.

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The protective effects of trace elements against side effects induced by ionizing radiation

  • Hosseinimehr, Seyed Jalal
    • Radiation Oncology Journal
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    • v.33 no.2
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    • pp.66-74
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    • 2015
  • Trace elements play crucial role in the maintenance of genome stability in the cells. Many endogenous defense enzymes are containing trace elements such as superoxide dismutase and metalloproteins. These enzymes are contributing in the detoxification of reactive oxidative species (ROS) induced by ionizing radiation in the cells. Zinc, copper, manganese, and selenium are main trace elements that have protective roles against radiation-induced DNA damages. Trace elements in the free salt forms have protective effect against cell toxicity induced by oxidative stress, metal-complex are more active in the attenuation of ROS particularly through superoxide dismutase mimetic activity. Manganese-complexes in protection of normal cell against radiation without any protective effect on cancer cells are more interesting compounds in this topic. The aim of this paper to review the role of trace elements in protection cells against genotoxicity and side effects induced by ionizing radiation.

An Empirical Study on the Integrated Customer Satisfaction Evaluation Model for New Product Development - Focused on Automobile Industry - (신제품 개발을 위한 통합 고객만족도 평가모델에 관한 실증적 연구 - 자동차 산업을 중심으로 -)

  • Kim Dong Nam;Cho Jai Rip
    • Journal of Korean Society for Quality Management
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    • v.32 no.4
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    • pp.113-124
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    • 2004
  • Customer satisfaction is becoming an increasingly salient topic in many firms and in academic research. One main rationale behind this interest is that customer satisfaction is believed to be associated with fruitful customer re-visit from the firm's point of view. Some country already had index models which can measure the degree of customer satisfaction. But, such models are ordinary models which used generally the scope of nation-wide /industry. Therefore, we needs some modifications to measure customer satisfaction for specific product & service and to provide the valuable feedback to specific firms. In this Perspectives, this study will evaluate the customer satisfaction index about automobile company and analyze it's result for valuable feedback. This study will present a model for an integrated customer satisfaction evaluation system which used structural equation modeling. Through this study, we anticipate that it will offer the measuring method about customer satisfaction and some guideline for product design process.

Research Study on the Application of AC Adjustable speed Drive for FD Fan Motor in power plant. (발전소 대용량 FD Fan 전동기의 교류 가변속 장치 (VVVF) 적용에 관한 연구)

  • Hur, Sung-Kwang;Rhew, Hong-Woo;Han, Kyung-Hie
    • Proceedings of the KIEE Conference
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    • 1992.07b
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    • pp.1203-1205
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    • 1992
  • Due to poor energy resources, the importance of energy saving has been greatly emphasized. It can be one method of energy saving to reduce the power. The AC adjustable speed drive systems show excellent efficiency, which have been developed in recent years. The adjustable speed drive system improves the efficiency in lightly load condition and extend the life span of motor by limiting the over-current at starting. The main topic of study is the results of energy saving and emergency transfer.

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Model Matching of Asynchronous Sequential Machines with Input Disturbance (입력 외란이 존재하는 비동기 순차 머신의 모델 매칭)

  • Yang, Jung-Min
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.57 no.1
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    • pp.109-116
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    • 2008
  • Model matching problem of asynchronous sequential machines is addressed in this paper. The main topic is to design a corrective controller such that the closed-loop behavior of the asynchronous sequential machine can follow a given model, i.e., their models can be "matched" in stable states. In particular, we assume that the considered asynchronous machine suffers from the presence of an input disturbance that can cause undesirable state transitions. The proposed controller can realize both model matching and elimination of the adverse effect of the input disturbance. Necessary and sufficient condition for the existence of a corrective controller that solves model matching problem is presented. Whenever controller exists, algorithms for their design are outlined and demonstrated in a case study.

Dynamic Reference-based Voltage Droop Control for VSC-MTDC System

  • Kim, Nam-Dae;Kim, Hak-Man;Park, Jae-Sae
    • Journal of Electrical Engineering and Technology
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    • v.10 no.6
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    • pp.2249-2255
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    • 2015
  • The use of voltage source converter multi-terminal direct current (VSC-MTDC) systems is anticipated to increase from the introduction of wind farms and super grids in the near future. Effective control of the DC voltage in VSC-MTDC systems is an important research topic. This paper proposes a new dynamic reference-based voltage droop control to control the DC voltage in VSC-MTDC systems more effectively. The main merit of the dynamic reference-based voltage droop control is that it can reduce the steady-state error in conventional voltage droop control by changing references according to the system operating conditions. The performance of the proposed control was tested in a hardware-in-the-loop simulation (HILS) system based on the OPAL-RT real-time digital simulator and four digital signal processing boards.

Engineering Applications of Jet Impingement Associated with Vertical Launching System Design

  • Hong, Seung-Kyu;Lee, Kwang-Seop
    • International Journal of Aeronautical and Space Sciences
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    • v.3 no.2
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    • pp.67-75
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    • 2002
  • In the course of missile system design, jet plume impingement is encountered in designing airframe as well as launchers, requiring careful investigation of its effect on the system. In the present paper, recent works on such topic are presented to demonstrate usefulness of CFD results in helping design the hardware. The jet impinging flow structure exhibits such complex nature as shock shell, plate shock and Mach disk depending on the flow parameters. The main parameters are the ratio of the jet pressure to the ambient pressure and the distance between the nozzle and the wall. In the current application, the nozzle contour and the pressure ratio are held fixed, but the jet impinging distance is varied to illuminate the characteristics of the jet plume with the distance. The same methodology is then applied to a complex vertical launcher system (VLS), capturing its flow structure and major design parameter. These applications involving jets are thus hoped to demonstrate the usefulness and value of CFD in designing a complex structure in the real engineering environment.

An Architecture for Integrating OODBs with WWW (웹 상에서 객체지향 데이터 베이스와 통합 아키텍처)

  • Haeng-Kon Kim;Jeun-Geun Kang
    • Journal of the Korea Computer Industry Society
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    • v.2 no.2
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    • pp.247-258
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    • 2001
  • The main topic of this paper is how to structure information so that the view of the web, both within and across web pages, is dynamically customizable. We present an architecture that integrates Object-Oriented Databases with the World Wide Web to organize such dynamic structures. Different non, or the same user at different times, could have different views of the web. We discuss several architectural variants and implementation issues. Our chosen architecture provides high flexibility for a wide variety of applications, ranging from software development environments to the IO-web system.

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Experimental studies on the fatigue life of shape memory alloy bars

  • Casciati, Sara;Marzi, Alessandro
    • Smart Structures and Systems
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    • v.6 no.1
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    • pp.73-85
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    • 2010
  • The potential offered by the thermo-mechanical properties of shape memory alloys (SMA) in structural engineering applications has been the topic of many research studies during the last two decades. The main issues concern the long-term predictability of the material behaviour and the fatigue lifetime of the macro structural elements (as different from the one of wire segments). The laboratory tests reported in this paper are carried out on bar specimens and they were planned in order to pursue two objectives. First, the creep phenomenon is investigated for two different alloys, a classical Ni-Ti alloy and a Cu-based alloy. The attention is then focused on the Cu-based alloy only and its fatigue characteristics at given temperatures are investigated. Stress and thermal cycles are alternated to detect any path dependency.