• 제목/요약/키워드: mass conservation

검색결과 517건 처리시간 0.033초

Piaget의 인지발달론에 기초한 국민학교 실과교과 내용분석(I) -만들기 영역을 중심으로- (A Study on the Content Analysis of Practical Course Subject in Elementary School based on the Piaget’s Cognitive Developmental Theory)

  • 정미경
    • 한국가정과교육학회지
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    • 제6권2호
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    • pp.133-145
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    • 1994
  • The purposes of this study are to investigate the relationship between the Piaget’s cognitive developmental theory and the practical course subject in elementary school which have the characteristics of skillful subject and living subject, and to discriminate the suitability of contents of the practical course subject for the childrens’level of cognitive development. This work could serve the theoretical background that the practical course subject presents practical experiences which lead the development of logicomathematical thinking abilities. The results of the content analysis shows that create activities develop the logicomathematical thinking abilities such as projective geometry, topology geometry, area conservation, length & distance conservation, and volume & mass conservation. And the most contents of the practical course subject are suitable for the childrens’level of cognitive development.

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직렬 연결된 PZT 구동 마이크로 압축기의 최적 설계 (Optimal Design of Serial Connected PZT driven Micro Compressor)

  • 이일환;윤재성;김민수
    • 대한설비공학회:학술대회논문집
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    • 대한설비공학회 2005년도 동계학술발표대회 논문집
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    • pp.421-426
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    • 2005
  • Optimal design of serial connected PZT driven micro compressor was investigated. Modeling equations were derived using energy equation and mass conservation equation. The results show that mass flow rate was increased as number of connected micro compresses is increased. As pressure difference between suction port and discharge port in compressor group is increased, connected compressors have much more mass flow rate than single compressor. Mass flow rate is also increased as driving frequency is increased. And optimal design scale is suggested for highest efficiency or highest mass flow rate.

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A CONSERVATIVE NONLINEAR DIFFERENCE SCHEME FOR THE VISCOUS CAHN-HILLIARD EQUATION

  • Choo, S.M.;Chung, S.K.
    • Journal of applied mathematics & informatics
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    • 제16권1_2호
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    • pp.53-68
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    • 2004
  • Numerical solutions for the viscous Cahn-Hilliard equation are considered using the Crank-Nicolson type finite difference method which conserves the mass. The corresponding stability and error analysis of the scheme are shown. The decay speeds of the solution in $H^1-norm$ are shown. We also compare the evolution of the viscous Cahn-Hilliard equation with that of the Cahn-Hilliard equation numerically and computationally, which has been given as an open question in Novick-Cohen[13].

몽골 도르릭나르스 유적 토기의 접합에 사용한 물질 분석 (Analysis of adhesive material for joining pottery fragments excavated from Duurlig Nars, Mongolia)

  • 윤은영;강형태
    • 보존과학회지
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    • 제30권1호
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    • pp.33-38
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    • 2014
  • AD 1세기로 추정되는 몽골 도르릭나르스 흉노 무덤에서 출토된 토기는 파단면을 따라 검은색의 유기물로 접합한 흔적이 남아있었다. 본 연구에서는 부착된 검은색 유기물의 특성을 확인하기 위해 GC-MS를 이용하여 성분분석 한 결과, 자작나무 껍질 타르의 특성 성분으로 알려진 루페올(Lupeol) 및 베툴린(Betulin) 등을 포함한 Triterpenoid 화합물이 확인되었다. 이를 통해 고대 몽골에서는 자작나무 껍질로 만든 타르를 사용하여 토기를 접합하였음을 알 수 있었다. 따라서 앞으로 고고자료에 잔존하는 유기물에 대하여 체계적인 과학적 조사가 이루어진다면 과거의 생활 모습에 대한 중요한 정보를 제공할 것으로 기대된다.

디젤엔진용 고압분사 유닛인젝터의 성능예측을 위한 사이클 시뮬레이션 (Cycle Simulation for the Performance Prediction of a High Pressure Unit Injection System of a Diesel Engine)

  • 김철호
    • 한국자동차공학회논문집
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    • 제9권1호
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    • pp.63-74
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    • 2001
  • In this study, a cycle simulation program of a Unit-Injection(UI) system was developed to estimate the injection performance of newly designed injection system. A fundamental theory of the simulation program is based on the conservation law of mass. Loss of fuel mass in the system due to leakage, compressibility effect of the liquid fuel and friction loss in the control volume was considered in the algorithm f the program. For the evaluation of the simulation program developed, the experimental result which was offered by the Technical Research Center of Doowon Precision Industry Co. was incorporated. Two main parameters; the maximum pressure in the plunger chamber and total fuel mass(kg) injected into the engine cylinder per cycle, were measured and compared with the simulation results. It was found that the maximum error rate of the simulation result to the experimental output was less than 3% in the rated rotational speed (rpm) range of the plunger cam.

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Thermal-hydraulic simulation and evaluation of a natural circulation thermosyphon loop for a reactor cavity cooling system of a high-temperature reactor

  • Swart, R.;Dobson, R.T.
    • Nuclear Engineering and Technology
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    • 제52권2호
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    • pp.271-278
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    • 2020
  • The investigation into a full-scale 27 m high, by 6 m wide, thermosyphon loop. The simulation model is based on a one-dimensional axially-symmetrical control volume approach, where the loop is divided into a series of discreet control volumes. The three conservation equations, namely, mass, momentum and energy, were applied to these control volumes and solved with an explicit numerical method. The flow is assumed to be quasi-static, implying that the mass-flow rate changes over time. However, at any instant in time the mass-flow rate is constant around the loop. The boussinesq approximation was invoked, and a reasonable correlation between the experimental and theoretical results was obtained. Experimental results are presented and the flow regimes of the working fluid inside the loop identified. The results indicate that a series of such thermosyphon loops can be used as a cavity cooling system and that the one-dimensional theoretical model can predict the internal temperature and mass-flow rate of the thermosyphon loop.

충격 댐퍼의 동특성과 가속 질량추가 현상에 대한 연구 (Dynamic Behaviors of the Impact Damper and the Accelerated Mass Loading)

  • 왕세명;박종찬
    • 한국소음진동공학회:학술대회논문집
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    • 한국소음진동공학회 2006년도 춘계학술대회논문집
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    • pp.396-401
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    • 2006
  • Dynamic behaviors of the impact damper are studied experimentally and numerically. In order to investigate wide range of excitation frequencies and amplitudes, a simple but high amplifying and bias-free experimental setup is designed. Experiments focused on the harsh operation condition demonstrate Accelerated mass loading which not only deteriorates the performance of the impact damper but also involves the structural resonance which should be avoided for the stability of the system. In the previous studies, instability or deterioration of the performance was reported for the off resonance frequency region. But this paper shows that the performance deterioration and structural resonances can be predicted. Using finite element modeling and analysis, accurate system parameters were derived and used for the numerical modeling employing the conservation of the momentum. Numerical study of the transient responses using 4th-order Runge-Kutta method demonstrates general performance of the system, and shows that accelerated mass loading phenomenon is deeply related with the vibration amplitudes and the mass of the auxiliary system.

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로터리 제습기의 일반 해석 모델 (Development of a General Analytical Model for Desiccant Wheels)

  • 김동선;이대영
    • 설비공학논문집
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    • 제25권2호
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    • pp.109-118
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    • 2013
  • The absence of a simple and general analytical model has been a problem in the design and analysis of desiccant-assisted air-conditioning systems. In this study, such an analytical model has been developed based on the approximate integral solution of the coupled transient ordinary differential equations for the heat and mass transfer processes in a desiccant wheel. It turned out that the initial conditions should be determined by the solution of four linear algebraic equations including the heat and mass transfer equations for the air flow as well as the energy and mass conservation equations for the desiccant bed. It is also shown that time-averaged exit air temperature and humidity relations could be given in terms of the heat and mass transfer effectiveness.

Purification and Cloning of an Extracellular Serine Protease from the Nematode-Trapping Fungus Monacrosporium cystosporium

  • Yang, Jin-Kui;Ye, Feng-Ping;Mi, Qi-Li;Tang, Song-Qing;Li, Juan;Zhang, Ke-Qin
    • Journal of Microbiology and Biotechnology
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    • 제18권5호
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    • pp.852-858
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    • 2008
  • An extracellular protease (Mc1) was isolated from the nematode-trapping fungus Monacrosporium cystosporium by gel filtration, anion-exchange, and hydrophobic interaction chromatographies. This protease had a molecular mass of approximately 38 kDa and displayed an optimal activity at pH 7-9 and $56^{\circ}C$ (over 30 min). Its proteolytic activity was highly sensitive to the serine protease inhibitor PMSF (phenylmethylsulfonylfluoride, 0.1 mM), indicating that it belonged to the serine-type peptidase group. The Michaelis constant ($K_m$) and $V_max$ for substrate N-Suc-Ala-Ala-Pro-Phe-pNA were $1.67{\times}10^{-4}\;M$ and 0.6071 $OD_{410}$ per 30 s, respectively. This protease could degrade a broad range of substrates including casein, gelatin, BSA (bovine serum albumin), and nematode cuticle. Moreover, the enzyme could immobilize the free-living nematode Panagrellus redivivus and the pine wood nematode Bursaphelenchus xylophilus, suggesting that it might playa role in infection against nematodes. The encoding gene of Mc1 was composed of one intron and two exons, coding for a polypeptide of 405 amino acid residues. The deduced amino acid sequence of Mcl showed 61.4-91.9% identity to serine proteases from other nematode-trapping fungi. Our results identified that Mcl possessed biochemical properties including optimal reaction condition and substrate preference that are different from previously identified serine proteases.