• 제목/요약/키워드: High step-up

검색결과 699건 처리시간 0.026초

폐기물 소각시설 주변 환경보건평가 중 스크리닝 단계에서의 우선순위 선정기법에 관한 연구 (Simple priority setting method for Screening in public health assessment of waste incineration facilities)

  • 김기영;홍승철
    • 환경영향평가
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    • 제21권5호
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    • pp.813-821
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    • 2012
  • Environmental and public health concern for the emission of air pollutants from burn-up process in waste incineration plants located in the vicinity of living environment was increased during the past decade. The purpose of this study was to suggest of the simple and rapid method of priority setting model for the decision of full-scale public health assessment. This method was consists of total 5-step. Step 1 was "secure the satellite map" and we can use the satellite map which serves from the website such as NAVER Co. Step 2 was "drawing mesh on the map" for catch the point of occupation of environmental sensitivity facilities, and step 3 was "identification and sorting of the facilities", Step 4 was "setting of weight" using the "weighted linear combination (WLC) method". Finally, all facility was sorted by score. As a result, we can set a priority of 145 facilities based on 177 facilities which managed in local government. Facilities in Seoul metropolitan area was high rank in priority list. On the other side, Facilities located at the country or rural area was low rank because of low occupation of the house and the environmental sensitivity facilities such as kindergarten, elementary school, and hospital. In this study, we suggested simple and rapid method that using for screening procedure of public health assessment.

하수처리를 위한 간헐 방류식 장기폭기 공정에서 아질산염의 축적에 영향을 미치는 인자 (Factors affecting nitrite build-up in an intermittently decanted extended aeration process for wastewater treatment)

  • 안규홍;박기영;이형집
    • 상하수도학회지
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    • 제13권1호
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    • pp.51-60
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    • 1999
  • An intermittently-aerated, intermittently-decanted single-reactor process (KIDEA process : KIST intermittently decanted extended aeration process) was applied for nitrogen removal from wastewater. Synthetic wastewater with chemical oxygen demand (COD): nitrogen (N) ratio of approximately 5.25: 1 was used. The average COD removal efficiency reached above 95%, and under optimal conditions nitrogen removal efficiency also reached above 90%. This process consisted of 72 minute aeration, 48 minute settling and 24 minute effluent decanting with continuous feeding of influent wastewater from the bottom of the reactor, and did not require a separate anoxic mixing-phase. In this process, nitritation ($1^{st}$ step of nitrification) was induced but nitratation($2^{nd}$ step of nitrification) was suppressed. Main factors responsible for the accumulation of nitrite ion in the experimental condition were free ammonium and dissolved oxygen. This condition of nitrite build-up accelerated by continuous feed flow in the bottom of the KIDEA reactor because of high concentration of ammonia nitrogen in the influent. This research provides one of answers to control nitrate build-up.

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자체 윤활 피스톤 씨일 링의 가스 누출과 마찰에 대한 연구 (A Study on the Gas Leakage and Friction of the Self-lubricating Piston Seal Rings)

  • 심현해;권오관;이규한;김병환;임윤철
    • Tribology and Lubricants
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    • 제12권4호
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    • pp.7-12
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    • 1996
  • Present study was undertaken to investigate the leakage and friction of self-lubricating piston seal rings. A crank-piston type gas leakage test set-up was constructed. The piston rings were made of PTFE-polyimide composite. The free gap configurations of the seal rings were butt and step types. Eccentric tension rings were used to give the seal rings prepressure between the seal rings and cylinder wall. Two sizes of the tension rings were installed to investigate their effect on the gas leakage and friction of the seal rings. The results showed that step type seal rings are superior than the butt types. High tension spring rings resulted in low leakage and high friction loss. In order to reduce the gas leakage and friction loss of the piston seal rings, there should be compromise between the number of ring stages and prepressure of the tension rings.

선형성이 우수한 과변조 기법의 DSP 구현 방법 (Implementation Method of Overmodulation Technique With High Linearity in DSP)

  • 김준석;김도현;이준희;이준석
    • 전력전자학회논문지
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    • 제27권2호
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    • pp.118-125
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    • 2022
  • With the aim to maximize the use of a given voltage source in the field of railway and electric vehicles, this study applies a technique for controlling the overmodulation region between the linear and the six-step regions. High linearity overmodulation techniques that do not use look-up table (LUT) to digital signal processor (DSP) using carrier based pulse width modulation (PWM) are proposed. Such technique requires the phase of the voltage vector at the point where the circular trajectory of the voltage command vector and hexagonal cross each other. Therefore, a method is proposed to obtain a phase of a voltage vector that is derived through an equation and applied to a carrier-based PWM. Validity of the proposed implementation method is confirmed through simulation and experiment.

Super-Lift DC-DC Converters: Graphical Analysis and Modelling

  • Zhu, Miao;Luo, Fang Lin
    • Journal of Power Electronics
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    • 제9권6호
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    • pp.854-865
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    • 2009
  • Super-lift dc-dc converters are a series of advanced step-up dc-dc topologies that provide high voltage transfer gains by super-lift techniques. This paper presents a developed graphical modelling method for super-lift converters and gives a thorough analysis with a consideration of the effects caused by parasitic parameters and diodes' forward voltage drop. The general guidelines for constructing and deriving graphical models are provided for system analysis. By applying it to examples, the proposed method shows the advantages of high convenience and feasibility. Both the circuit simulation and experimental results are given to support the theoretical analysis.

배터리 저장 시스템용 고승압 양방향 컨버터 (High Step-Up Bidirectional DC-DC Converter for Battery Storage System)

  • Zhang, Hai-Long;Park, Sung-Jun;Kim, Dong-Hee
    • 전력전자학회:학술대회논문집
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    • 전력전자학회 2018년도 전력전자학술대회
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    • pp.320-321
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    • 2018
  • A non-isolated high voltage gain bidirectional DC-DC converter for battery storage system has been presented in this paper. The topology is composed of boost converter and traditional SEPIC converter. The proposed converter can achieve higher voltage conversion ratio with reduced voltage and current stresses in the switches. In additional, a reduced number of components are included in this topology. The PSIM simulation is carried to validate the analysis and operation of the converter.

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Large viewing angle walk through type display using smoke screen

  • Sato, Koki;Takano, Kunihiko;Ohki, Makoto
    • 한국방송∙미디어공학회:학술대회논문집
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    • 한국방송공학회 2009년도 IWAIT
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    • pp.790-793
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    • 2009
  • In the case of projection type display, it needs to use the screen in order to project the image clearly and wide viewing angle. We have been developing the step in type display system using the smoke screen. However, the image with smoke screen was flickered by gravity and air flow. Then we considered to reduce the flicker of the image and we found that flicker can be reduced and viewing angle becomes more large. This time we report the large viewing angle step in type display system using screen made up with very small particle size smoke and flow controlled nozzle. Hence, at first we considered the most suitable particle for the screen and then the shape of screen and then we constructed the array of flow controlled smoke screen. By the results of experiment we could get considerably high contrast flicker-less image and get the viewing angle more than $60^{\circ}$ by this flow controlled nozzle attached new type smoke screen and make clear the efficiency of this method.

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산화-환원 싸이클 조업에 의한 고순도 수소생성 (High Purity Hydrogen Production by Redox Cycle Operation)

  • 전법주;박지훈
    • 한국수소및신에너지학회논문집
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    • 제21권5호
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    • pp.355-363
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    • 2010
  • High purity hydrogen, 97-99 vol.%, with CO at just ppm levels was obtained in a fixed bed of iron oxide employing the steam-iron cycle operation with reduction at 823K and oxidation in a steam-$N_2$ mixture at 773K TGA experiments indicated that temperature of the reduction step as well as its duration are important for preventing carbon build-up in iron and the intrusion of $CO_2$ into the hydrogen product. At a reduction temperature of 823K, oxide reduction by $H_2$ was considerably faster than reduction by CO. If the length of the reduction step exceeds optimal value, low levels of methane gas appeared in the off-gas. Furthermore, with longer durations of the reduction step and CO levels in the reducing gas greater than 10 vol.%, carbidization of the iron and/or carbon deposition in the bed exhibited the increasing pressure drop over the bed, eventually rendering the reactor inoperable. Reduction using a reducing gas containing 10 vol.% CO and a optimal reduction duration gave constant $H_2$ flow rates and off-gas composition over 10 redox reaction cycles.

Step aerobics의 RPE가 여고생의 면역기능에 미치는 영향 (The Effects of RPE of Step Aerobics on the Immunologic Function of High School Girls)

  • 권선옥;정선태
    • 생명과학회지
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    • 제20권2호
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    • pp.304-313
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    • 2010
  • J시 소재 K여자고등학교 1학년 중에서 %fat이 30% 이상인 24명을 유의추출법에 의해 운동그룹 A (8명), B (8명) 그룹과 통제그룹(8명)으로 3그룹으로 구분하여 Borg의 주관적운동강도를 이용, A그룹은 RPE 15-17 (hard-very hard; 힘듦-매우 힘듦)${\times}$3 sets, B그룹은 RPE 11-13 (fairly light-somewhat hard; 알맞음-약간 힘듦)${\times}$3 sets로 설정하여 step aerobics (step box: 길이 68 cm, 폭 28 cm, 높이 15 cm, 무게 450 g)를 1일 50-60분간, 주3회(월, 수, 금)로 총 8주간 실시하였다. 본 연구는 step aerobics의 RPE가 비만 여고생의 면역기능(Neutrophil, Lymphocyte, Monocyte, Eosinophil, Basophil, IgG, IgA, IgM)에 어떠한 영향을 미치는가를 알아보는 것이었다. 자료처리는 SPSS Ver. 14.0을 이용하여 집단과 시기 간 상호작용의 효과를 알아보기 위하여 repeated two-way ANOVA를, 집단 내 운동 전 후는 paired t-test를 실시하였고, 집단 간은 변화율(% diff.)을 구하여 one-way ANOVA를 실시하여 다음과 같은 결론을 얻었다. WBC에서, 집단 내 비교에서 A그룹은 Neutrophil, Monocyte, Basophil, Eosinophil 모두 증가하였으나 Lymphocyte는 변화가 없었고, B그룹은 Eosinophil은 감소하였으나 Neutrophil, Lymphocyte, Monocyte, Basophil 모두 변화가 없었으며, 통제군은 Neutrophil, Basophil, Eosinophil은 감소하였으나 Lymphocyte와 Monocyte는 변화가 없었다. 집단 간 비교의 Neutrophil은 A그룹이 B그룹과 통제군보다 더 많이 증가하였고, Lymphocyte는 집단 간 차이가 없었으며, Monocyte는 A, B그룹이 통제군보다 많이 증가하였다. Basophil과 Eosinophil은 A그룹이 B그룹과 통제군보다 더 많이 증가하였다. Immunoglobin에서, 집단 내 비교에서 A그룹은 IgG는 증가하였으나 IgA와 IgM는 변화가 없었고, A그룹은 IgA는 증가하였으나 IgG는 감소하였고 IgM은 변화가 없었다. 통제군은 IgG은 감소하였으나 IgA와 IgM은 변화가 없었다. 집단 간 비교의 IgA는 A그룹이 통제군보다 증가하였고, IgG는 A그룹이 B그룹과 통제군보다 증가하였으나 IgM은 집단 간 차이가 없었다. 요약하면 세 집단 모두 운동프로그램 전 후의 WBC와 Ig 수준이 연령에 맞게 참고치 내의 수준에 머물렀지만 step aerobics를 RPE 15-17로 실시한 A그룹의 경우가 가장 많은 측정항목에서 증가를 보였고, 이 결과는 참고치 범위 내에서 면역기능의 항진을 보여주는 것으로 면역기능의 향상을 위한 step aerobics의 RPE 강도는 힘듦-매우 힘듦(15-17)의 수준으로 실시하는 것이 효과적인 것으로 생각된다.

A New Phase-Locked Loop System with the Controllable Output Phase and Lock-up Time

  • Vibunjarone, Vichupong;Prempraneerach, Yothin
    • 제어로봇시스템학회:학술대회논문집
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    • 제어로봇시스템학회 2003년도 ICCAS
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    • pp.1836-1840
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    • 2003
  • This paper, we propose a new phase-locked loop (PLL) system with the controllable output phase, independent from the output frequency, and lock-up time. This PLL system has a dual control loop is described, the inner loop greatly improved VCO characteristic such as faster speed response as well as higher operation bandwidth, to minimize the effect of the VCO noise and the power supply variation and also get better linearity of VCO output. The main loop is the heart of this PLL which greatly improved the output frequency instability due to the external high frequency noise coupling to the input reference frequency also the main loop can control the output phase, independent from the output frequency, and reduce the lock-up time of the step frequency response. The experimental results confirm the validity of the proposed strategy.

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