• 한국분무공학회지
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• 제7권2호
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• pp.7-15
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• 2002

A particle flow visualization, electrostatic charging measurement and separation of triboelectrically charged particles in the external electric field by a fluidized bed tribocharger are conducted for the removal of PVC particles from mixed waste plastics. The laboratory-scale triboelectrostatic separation system consists of the fluidized bed tribocharger, a separation chamber, a collection chamber and a controller. PVC and PET particles can be imparted negative and positive surface charges respectively due to the difference of triboelectric charging series between particles and particles in the fluidized bed tribocharger, and can be separated by passing them through an external electric field. To visualize these charged particles, He-Ne laser is used with cylindrical lenses to generate a sheet beam. In the charging measurement, the particle motion analysis system (PMAS), capable of determining particle velocity and diameter. is used to non-intrusively measure particle behavior in high strength electric field. The average charge-to-mass ratios of PVC and PET particles are $1.4\;and\;1.2{\mu}C/kg$, respectively. The highly concentrated PVC (91.9%) can be recovered with a yield of about 96.1% from the mixture of PVC and PET materials for a single-stage processing. The triboelectrostatic separation system using the fluidized tribocharger shows the potential to be an effective method for removing PVC from mixed plastics for waste plastic recycling.

• 한국표면공학회지
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• 제46권1호
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• pp.42-47
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• 2013

The strain-induced phase transformation from austenite to martensite is responsible for the high strength and ductility of TRIP steels. However high strength steels are susceptible to hydrogen embrittlement. This study aimed to evaluate the effects of hydrogen on the behavior of hydrogen delayed fracture in TRIP steel with hydrogen charging conditions. The electrochemical hydrogen charging was conducted at each specimen with varying current density and charging time. The relationship between hydrogen concentration and mechanical properties of TRIP steel was established by SP test and SEM fractography. The maximum loads and displacements of the TRIP steel in SP test decreased with increasing hydrogen charging time. The results of SEM fractography investigation revealed typical brittle mode of failure. Thus it was concluded that hydrogen delayed fracture in TRIP steel result from the diffusion of hydrogen through the ${\alpha}$' phase.

• 한국표면공학회지
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• 제45권5호
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• pp.212-217
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• 2012

High strength steel sheets used for automobile outer-panels have been intensively studied for developing a lightweight automobile under a strong pressure of the requirements for enhancing the mileage and energy saving in production of automobile parts. It is known that high strength steels are susceptible to hydrogen embrittlement, The susceptibility to hydrogen embrittlement increases with increasing its strength. However, the effect of hydrogen on the fracture behavior of high strength steels, though investigated extensively, has not been fully understood. In this paper, hydrogen was charged with 590DP steels by electrochemical method and its content was measured by hydrogen determinator with the different charging conditions. It was shown that the SP energy and maximum load decreased with increasing charging time. The results of SEM-fractography investigation for the hydrogen contained samples showed that a small portion of dimples on cleavage-fractured surface were observed and the size of the dimples were decreased with increasing hydrogen charging time.

• 한국표면공학회지
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• 제47권5호
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• pp.257-262
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• 2014

In this paper, the behavior of hydrogen embrittlement of 680MPa DP sheet steel according to hydrogen charging conditions in acid and alkali electrolytes atmosphere was investigated. At this time, 0.5 M $H_2SO_4$ and 0.5M NaOH was used for electrolytes atmosphere and the effect on embrittlemnet of 680MPa DP sheet steel according to current density and charging time was evaluated by the change of subsurface microhardness in DP specimens chared hydrogen. As a result of this experiment, the microhardness of the layer directly below the surface was increased more than the microhardness of the subsurface zone in both electrolytes cases, but the change of the subsurface microhardness in both electrolytes was more affected by the increase of charging time than the increase of current density. The microhardness of subsurface zone in 0.5 M $H_2SO_4$ acid electrolyte was increased more than the microhardness in 0.5M NaOH alkali electrolyte. It was supposed that acid atmosphere was more sensitive to hydrogen embrittlement than alkali atmosphere on electrolyte atmosphere of hydrogen charge.

• 설비공학논문집
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• 제18권11호
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• pp.851-858
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• 2006

[ $CO_2$ ] and propane mixtures, which are environmentally benign, nontoxic, low in price, and compatible with materials and lubricants, were considered as promising alternative refrigerants. A fully instrumented air-conditioning system was developed for a precise performance evaluation of pure $CO_2$ and $CO_2/propane$ mixtures. In this paper, the effect of the charging amount and circulation concentration on the cooling performance of the system using $CO_2$ and propane mixtures was tested and discussed. Pure $CO_2$ and 85/15, 75/25 and 60/40 binary blends by the charged mass percentage of $CO_2/propane$ were selected as working fluids. An optimum charging amount was proposed as a parameter instead of the degree of subcooling, which can not be well defined in the transcritical cycle, to properly compare the performance between the transcritical and subcritical cycles.

• 전기전자학회논문지
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• 제15권4호
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• pp.305-312
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• 2011

A primary interest of this work is to develop an efficient and powerful repetitive pulser system for the application of ultra wide band generation. The important component of the pulser system is a small-sized coaxial type spark gap with planar electrodes filled with SF6 gas. A repetitive switching action by the coaxial spark gap generates two consecutive pulses in less than a microsecond with rise times of a few hundred picoseconds (ps). A set of several parameters for the repetitive switching of the spark gap is required to be optimized in charging and discharging systems of the pulser. The parameters in the charging system include a circuit scheme, circuit elements, the applied voltage and current ratings from power supplies. The parameters in the discharging system include the spark gap geometry, electrode gap distance, gas type, gas pressure and the load. The characteristics of the spark gap discharge, such as breakdown voltage, output current pulse and recovery rate are too dynamic to control by switching continuously at a high pulse repetition rate (PRR). This leads to a low charging efficiency of the spark gap system. The breakthrough of the low charging efficiency is achieved by a parallel operation of two spark gaps system. The operational behavior of the two spark gaps system is presented in this paper. The work has focused on improvement of the charging efficiency by scaling the PRR of each spark gap in the two spark gaps system.

• 한국ITS학회 논문지
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• 제21권6호
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• pp.21-35
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• 2022

최근 정부의 적극적인 지원정책과 함께 전기차 이용자들이 급증하고 있으며, 이로 인해 이용자 중심의 충전인프라 구축에도 많은 관심을 쏟아지고 있다. 다양한 정책의 수립과 함께 건물 특성에 기반한 총량적인 전기차 충전기 보급대수 기준은 마련되고 있으나, 장소별 특성에 기반한 완속과 급속충전기 적정 보급 비율에 대한 연구는 제한적이다. 이에 본 연구에서는 전기차 이용자들을 대상으로 진행한 설문조사를 통해 수집한 장소 유형별 공용 완속충전기 보급 비율 자료를 바탕으로 적정 보급비율을 도출하고, 개인별로 충전 환경 요구가 어떻게 차별적으로 유형화되고 이들이 어떠한 특성과 연관되는지 분석하였다. 분석 결과, 10% 이하의 완속 충전기가 필요한 유형, 40-60% 수준의 완속충전기가 필요하여 완속과 급속충전기의 균등 분배가 필요한 유형, 완속이 80% 이상 필요한 유형 등 총 세 가지 장소 유형을 도출할 수 있었다. 또한 잠재계층 군집분석을 통해 개인별로 서로 다른 장소유형별 완속충전기 필요 수준을 분류한 결과 5개 군집으로 유형화할 수 있었으며, 이들은 사회경제적 변수, 차량의 특성, 통행 및 충전행태와 연관된 것으로 나타났다. 특히, 충전행태와 주말 통행행태 그리고 성별, 소득과의 연관성이 높은 것으로 나타났다. 본 연구의 분석결과는 향후 충전인프라 정책 수립 및 전기차 시장의 변화에 따른 충전인프라 보급 기준 마련에 활용될 수 있을 것으로 사료된다.

• 한국표면공학회지
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• 제15권3호
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• pp.146-151
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• 1982

The electrochemical reaction behavior of nickel electrode of the nickel-cadium battery system in potassium hydroxide solution has been studied by cyclic voltammetry, controlled potential electrolysis and X-ray diffraction method. It has been found that the reaction mechanism of positive nickel electrode for charging was assumed to be proten transfer step with a rate controlling diffusion process and char-ging state of positive electrode was amorphous $\beta$-NiOOH.

• 한국산업정보학회논문지
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• 제11권2호
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• pp.9-17
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• 2006

차등 인터넷 서비스를 효과적으로 운영하는 접근법에 대한 연구가 최근에 활발히 진행되고 있다. 인터넷 이용자와 공급자(ISP) 각각의 사회적 편익의 변화에 따른 대역폭 시장 참여자들의 관계를 고찰한다. 차별화 된 QoS를 원하는 시간대에 사용하려는 사용자(고객)에게 더 높은 요금지불을 감내해야 한다는 것은 기본적인 경제관점이다 대역폭 리소스의 과다사용, 적절사용, 과소사용에 따른 차등화 된 요금을 적용하기 위해 실질적으로 사용자에 의해 소비된 리소스의 크기 v(t)를 기반으로 하는 누적요금계획(CPS) 기법을 제시한다. CPS는 미래에 상업적 네트워크의 중요한 관리기능을 결정한다. 이 논문에서는 EWM 기법을 적용하여, CPS를 이용하여 유연하면서도 합리적인 인터넷 요금구조, 시장관리기법, 투명성, 예측성, 단순성 등이 고려되는 인터넷 요금부과 시스템의 수정된 구현기법을 제시한다.

• 대한기계학회논문집B
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• 제26권4호
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• pp.570-577
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• 2002

Charged liquid particle's behavior in electric and flow field was simulated to define the effect of electric field on the contact area and its dispersion. For the simulation of flow and electric field finite volume method was applied. To find out the particle's moving path in that field lagrangian equation of motion was solved by Runge-Kutta methods. We assumed that the particle was charged 10% of Rayleigh limit while the particle passing through the electrode and the particle does not have an effect on the electric field. In case of 30[Kv] of voltage charging the particles injected from the central 60% of the nozzle injection area adhere to the grounded moving plate and no dispersion occurred. Increasing the charged voltage to 40[Kv], it brought about the same phenomena as that of 30[Kv] charging except the dispersion. Voltage increasing from 30[Kv] to 40 [Kv] caused higher Coulomb force acts on the particle and it made the particle dispersion.