• 제목/요약/키워드: Air-Water Interface

검색결과 282건 처리시간 0.022초

배수갑문 주위의 흐름현상에 대한 3차원 난류 수치모형과 수리모형실험의 비교 (Comparison between a 3 Dimensional Turbulent Numerical Model and Hydraulic Experiment Model for the flow phenomenon around a Lock Gate)

  • 이상화;장은철;하재율
    • 한국해안해양공학회지
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    • 제19권2호
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    • pp.162-169
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    • 2007
  • 본 연구는 갑문 개방시 유출부의 흐름 현상을 수리모형실헐 결과와 3차원 수치모형실험을 비교 분석하는데 역점을 두고 있다. 대상 갑문은 군장(군산-장항)국가산업단지내의 솔리천에서 유입되는 홍수량 $218m^3/s$을 배제하기 위해서 설계된 배수갑문이다. 수치실험에 사용된 모형은 상용 전산유체역학 프로그램인 ANSYS CFX-10의 ${\kappa}-{\epsilon}$ 난류모형이다. CFX-10의 장점은 난류 흐름에 대해 현상을 양호하게 시뮬레이션 할 수 있으며 특히 물과 공기 접촉면(two phase interface)인 경계층에서 흐름 분리현상을 비교적 뚜렷하게 해석할 수 있다. 수치실험에서 해석된 유속 및 수면의 흐름 형태는 수리모형실험과 유사하게 나타났다.

벽지용 천연마늘접착제의 제조 및 접착성능 (Preparation and Bonding Properties of Natural Garlic Adhesives for Wallpaper)

  • 노정관;이진화
    • 접착 및 계면
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    • 제12권4호
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    • pp.125-132
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    • 2011
  • 최근 실내공간에서의 안전성을 확보하기 위해 유해물질의 방출이 없는 천연재료의 사용이 요구됨에 따라 음식재료인 마늘을 이용한 도배용 천연마늘접착제의 제조와 그 성능에 관하여 검토하였다. 마늘을 이용한 천연접착제는 생마늘을 물로 추출하여 탄수화물과 단백질을 분리 및 농축하는 방법에 의해 제조가 가능하였다. 제조한 천연마늘접착제의 접착성능은 불휘발분의 양에 의해 크게 영향 받았으며, 최적의 불휘발분은 60% 전후였다. 제조한 천연마늘 수지의 특성은 불휘발분 62%, 밀도 $1.3g/cm^3$, 점도 2,789 mPa s, pH 6.6이었다. 또한, 마늘 접착제의 접착성능은 KS의 기준을 크게 상회하였으며, 방부제의 첨가 없이도 마늘이 가지고 있는 항균성을 유지하고 있었으며, 특히 휘발성유기화합물과 폼알데하이드의 방산이 거의 없는 매우 안전한 천연접착제로서의 이용이 가능할 것으로 기대된다.

설비공학 분야의 최근 연구 동향: 2014년 학회지 논문에 대한 종합적 고찰 (Recent Progress in Air-Conditioning and Refrigeration Research: A Review of Papers Published in the Korean Journal of Air-Conditioning and Refrigeration Engineering in 2014)

  • 이대영;김사량;김현정;김동선;박준석;임병찬
    • 설비공학논문집
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    • 제27권7호
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    • pp.380-394
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    • 2015
  • This article reviews the papers published in the Korean Journal of Air-Conditioning and Refrigeration Engineering during 2014. It is intended to understand the status of current research in the areas of heating, cooling, ventilation, sanitation, and indoor environments of buildings and plant facilities. Conclusions are as follows. (1) The research works on the thermal and fluid engineering have been reviewed as groups of heat and mass transfer, cooling and heating, and air-conditioning, the flow inside building rooms, and smoke control on fire. Research issues dealing with duct and pipe were reduced, but flows inside building rooms, and smoke controls were newly added in thermal and fluid engineering research area. (2) Research works on heat transfer area have been reviewed in the categories of heat transfer characteristics, pool boiling and condensing heat transfer and industrial heat exchangers. Researches on heat transfer characteristics included the results for thermal contact resistance measurement of metal interface, a fan coil with an oval-type heat exchanger, fouling characteristics of plate heat exchangers, effect of rib pitch in a two wall divergent channel, semi-empirical analysis in vertical mesoscale tubes, an integrated drying machine, microscale surface wrinkles, brazed plate heat exchangers, numerical analysis in printed circuit heat exchanger. In the area of pool boiling and condensing, non-uniform air flow, PCM applied thermal storage wall system, a new wavy cylindrical shape capsule, and HFC32/HFC152a mixtures on enhanced tubes, were actively studied. In the area of industrial heat exchangers, researches on solar water storage tank, effective design on the inserting part of refrigerator door gasket, impact of different boundary conditions in generating g-function, various construction of SCW type ground heat exchanger and a heat pump for closed cooling water heat recovery were performed. (3) In the field of refrigeration, various studies were carried out in the categories of refrigeration cycle, alternative refrigeration and modelling and controls including energy recoveries from industrial boilers and vehicles, improvement of dehumidification systems, novel defrost systems, fault diagnosis and optimum controls for heat pump systems. It is particularly notable that a substantial number of studies were dedicated for the development of air-conditioning and power recovery systems for electric vehicles in this year. (4) In building mechanical system research fields, seventeen studies were reported for achieving effective design of the mechanical systems, and also for maximizing the energy efficiency of buildings. The topics of the studies included energy performance, HVAC system, ventilation, and renewable energies, piping in the buildings. Proposed designs, performance performance tests using numerical methods and experiments provide useful information and key data which can improve the energy efficiency of the buildings. (5) The field of architectural environment was mostly focused on indoor environment and building energy. The main researches of indoor environment were related to the evaluation of work noise in tunnel construction and the simulation and development of a light-shelf system. The subjects of building energy were worked on the energy saving of office building applied with window blind and phase change material(PCM), a method of existing building energy simulation using energy audit data, the estimation of thermal consumption unit of apartment building and its case studies, dynamic window performance, a writing method of energy consumption report and energy estimation of apartment building using district heating system. The remained studies were related to the improvement of architectural engineering education system for plant engineering industry, estimating cooling and heating degree days for variable base temperature, a prediction method of underground temperature, the comfort control algorithm of car air conditioner, the smoke control performance evaluation of high-rise building, evaluation of thermal energy systems of bio safety laboratory and a development of measuring device of solar heat gain coefficient of fenestration system.

정수장 슬러지 폭기가 방류수 망간 및 클로로포름에 미치는 영향 (The Aeration to Improve Manganese and Chloroform of Effluent at Sludge Thickener of the Conventional Water Treatment Plant)

  • 최일경;백인호;정찬우;이성진;박정욱
    • 대한환경공학회지
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    • 제36권2호
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    • pp.113-118
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    • 2014
  • 전 국가적으로 많은 정수장에서는 강화된 수질기준을 준수하는데 많은 어려움을 겪고 있다. 일반적으로 정수장 배출수처리시설은 고탁도를 기준으로 설계되기 때문에, 평상시에는 설계된 기간보다 장기간 체류할 수밖에 없는 실정이다. 평균 혹은 저탁도 원수가 유입되는 대부분 기간 동안 슬러지는 농축조에서 장기체류하기 때문에 혐기화되어, 용해성 망간 및 클로로포름이 형성된다. 위 문제를 해결하기 위해서 경제적이고, 손쉽게 도입 가능한 슬러지 폭기 공법을 개발하였으며, 본 연구는 이 공법의 원리 및 효과를 분석한 것이다. 슬러지 폭기 공법의 원리는 산화된 입자성 망간이 용해성 망간으로 환원되는 것을 방지하며, 생성된 클로로포름을 대기중으로 배출 제거시키며, 슬러지 입자를 균질화 시켜 침강성을 개선하는 것이다. 위 공법의 효과분석을 위하여 정수장 농축조에서 슬러지를 폭기시킨 후 상징수의 망간 및 클로로포름을 측정하고, 슬러지의 고-액 계면의 높이를 측정한 결과, 비폭기 경우에 비해 망간은 41%, 클로로포름은 62% 슬러지 부피는 35% 감소되는 효과를 얻었다.

금 합금 보철물의 교합면 삭제로 인한 임플란트-골 계면으로의 열전달에 관한 연구 (Study of heat transfer to the implant-bone interface induced by grinding of occlusal surface of implant gold prosthesis)

  • 조재영;강선녀;정창모;윤미정;허중보;전영찬
    • 대한치과보철학회지
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    • 제50권1호
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    • pp.29-35
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    • 2012
  • 연구 목적: 임플란트-골 계면에서 발생하는 과도한 열은 골유착을 저해하여 임플란트의 실패를 유발한다. 이에 이번 연구에서는 임플란트 금 합금 보철물의 교합면 삭제시 임플란트-골 계면으로의 열전달 양상과 냉각 방식의 효율성을 알아 보고자 하였다. 연구 재료 및 방법: 온도 감지 장치 제작을 위하여 Internal cone 연결형태의 임플란트에 16개의 K형 열전대를 부착하여 아크릴릭 레진에 포매하였다. 치과용 금 합금과 주조용 abutment를 사용하여 교합면에 3개의 요철을 가지는 시편을 10개 제작하였고, 연결 나사를 이용하여 임플란트와 연결한 뒤 온도 감지 장치를 $37^{\circ}C$ 유지되는 수조에 위치시켰다. 저속 핸드피스와 green stone bur를 이용하여 30초 동안 보철물의 요철을 삭제하였는데, 무냉각군, 공기 냉각 군, 물 분사 냉각 군으로 나누어 요철을 삭제하였다. 보철물이 삭제 되는 동안 임플란트의 부위별로 온도가 0.05초 간격으로 기록되었고, 삭제를 멈춘 뒤에도 무 냉각 군의 경우 임계 온도인 $47^{\circ}C$ 이하로 온도가 하강할 때까지, 공기 냉각군과 물 분사 냉각군의 경우 삭제 중단 후 30초 동안 추가로 온도를 기록하였다. 냉각 방식에 따른 임플란트-골 계면의 온도를 알아보고, 임플란트의 부위별 온도변화의 유의차를 알아보기 위하여 one-way ANOVA를 실시하였고, Turkey HSD 이용하여 95% 유의수준에서 사후 검증하였다. 결과: 무 냉각 군은 임플란트-골 계면의 온도가 $47^{\circ}C$ 이상으로 상승하였으며, 임플란트의 경부에서 유의하게 높은 열이 측정되었다(P>.05). 공기냉각군과물분사냉각군은 임플란트-골 계면의 온도가 $47^{\circ}C$ 이하로 유지되었다. 무 냉각 군에서 임플란트 경부의 온도가 $47^{\circ}C$에 도달되는 데는 약 $10.8{\pm}1.5$초가 소요되었다. 공기 냉각 군과 물 분사 냉각 군 사이에서는 임플란트-골 계면 온도의 유의차가 없었다(P>.05). 결론: 이상의 결과로부터 임플란트 금 합금 보철물의 교합면 삭제 시, 임플란트 주위 조직에 위해를 가할 수 있는 임계 온도 이상의 열이 발생했음을 알 수 있었으며, 냉각 방식은 공기 냉각과 물 분사 냉각 모두 효과적이라고 생각된다.

A numerical study on the dispersion of the Yangtze River water in the Yellow and East China Seas

  • Park, Tea-Wook;Oh, Im-Sang
    • Journal of the korean society of oceanography
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    • 제39권2호
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    • pp.119-135
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    • 2004
  • A three-dimensional numerical model using POM (the Princeton Ocean Model) is established in order to understand the dispersion processes of the Yangtze River water in the Yellow and East China Seas. The circulation experiments for the seas are conducted first, and then on the bases of the results the dispersion experiments for the river water are executed. For the experiments, we focus on the tide effects and wind effects on the processes. Four cases of systematic experiments are conducted. They comprise the followings: a reference case with no tide and no wind, of tide only, of wind only, and of both tide and wind. Throughout this study, monthly mean values are used for the Kuroshio Current input in the southern boundary of the model domain, for the transport through the Korea Strait, for the river discharge, for the sea surface wind, and for the heat exchange rate across the air-sea interface. From the experiments, we obtained the following results. The circulation of the seas in winter is dependent on the very strong monsoon wind as several previous studies reported. The wintertime dispersion of the Yangtze River water follows the circulation pattern flowing southward along the east coast of China due to the strong monsoon wind. Some observed salinity distributions support these calculation results. In summertime, generally, low-salinity water from the river tends to spread southward and eastward as a result of energetic vertical mixing processes due to the strong tidal current, and to spread more eastward due to the southerly wind. The tide effect for the circulation and dispersion of the river water near the river mouth is a dominant factor, but the southerly wind is still also a considerable factor. Due to both effects, two major flow directions appear near the river mouth. One of them is a northern branch flow in the northeast area of the river mouth moving eastward mainly due to the weakened southerly wind. The other is a southern branch flow directed toward the southeastern area off the river mouth mostly caused by tide and wind effects. In this case, however, the tide effect is more dominant than the wind effect. The distribution of the low salinity water follows the circulation pattern fairly well.

타액에 오염된 상아질에 대한 콤포머의 접합양상 (THE ADHESIVE PATTERNS OF COMPOMER TO SALIVA-CONTAMINATED DENTIN)

  • 조영곤;김병태;이석종
    • Restorative Dentistry and Endodontics
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    • 제25권4호
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    • pp.575-586
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    • 2000
  • In this study, adaptation of compomer to saliva contaminated dentin was evaluated with scanning electron microscope(SEM) and confocal laser scanning microscope(CLSM). For the SEM study, the occulusal surfaces of thirty two molar teeth were grounded to exposure dentin surfaces. The specimen were randomly assigned to control and three experimental groups with four samples in each group. In control group, Dyract and F-2000 compomer were bonded on the specimens according to the manufactures direction. Experimental groups were subdivided into three groups. They were contaminated with saliva on dentin surfaces ; Experimental group 1 : Saliva was dried with compressed air. Experimental group 2 : Saliva was rinsed with air-water spray and dried. Experimental group 3 : After polymerization of an adhesive, they were contaminated with saliva, and then saliva was rinsed with air-water spray and dried. Dyract and F-2000 compomer were bonded on saliva-treated dentin surfaces. The interfaces between dentin and compomer were observed with SEM. For the CLSM study, Class V cavities were prepared in buccal and ligual surfacess of thirty two molars. The specimens were divided into control and experimental groups. Class V cavities in experimental group were contaminated with saliva and those surfaces in each experimental groups received the same treatments as for the SEM study. Cavities were applied Prime & Bond 2.1 and F-2000 compomer primer/adhesive that were mixed with fluorescein, and then were filled with Dyract and F-2000 compomer. Specimens were embedded in transparent acrylic resin and sectioned buccolingual1y with diamond wheel saw, and then mounted on cover slide for CLSM study. The interface between cavity and compomer was observed by fluoresence imaging with a CLSM. The results were as follows : 1. In SEM exammination of Dyract group, control group, experimental group 2, 3 showed close adaptation to dentin and hybrid layer of $3{\sim}4{\mu}m$ diameter. Interfacial gap between compomer and dentin in experimental group 1 was wider than in control group. 2. In SEM examination of F-2000 group, adaptation to dentin of control group was closer than Dytact control group, but hybrid-like layer was not observed. Interfacial gap between compomer and dentin in experimental group 1 was wider than in Dyract experimental group 1. 3. In dissolution specimens of Dyract and F-2000 group, resin tags penetrated through dentinal tubules in control group and experimental group 1 and 3, but the penetration of resin tag was irregular and partial in experimental group 1. 4. In CLSM exammination of Dyract and F-2000 group, adhesive patterns of control and experimental groups showed same as in SEM. This result suggests the treatment methods, rinsing & drying, repeating all adhesive procedures, will produce good effect on adaptation of compomer to dentin if the dentin surface or polymerized adhesive is contaminated by saliva.

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G4-48PyA 덴드리머 박막의 금속이온 착체 효과 (Effect of Complex with Metal Ions of G4-48PyA Dendrimer Thin Films)

  • 정상범;유승엽;박은미;김정균;박재철;권영수
    • 대한전기학회:학술대회논문집
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    • 대한전기학회 2001년도 추계학술대회 논문집 전기물성,응용부문
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    • pp.131-133
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    • 2001
  • Dendrimers represent a new class of synthetic macromolecules characterized by a regularly branched treelike structure. Peculiar features of the dendritic geometry are the large number of end groups as well as the shape persistence in higher generations, approaching spherical geometry. And one of the most peculiar characteristics of dendritic macromolecules is their controlled molecular structure and orientation, which means that they have a practical application in achieving a highly organized molecular arrangement. We attempted to fabricate a G4-48PyA dendrimer LB films containing 48 pyridinealdoxime functional end group that could form a complex structure with metal ions. Also, we investigated the surface activity of dendrimer films at air-water interface. And we have studied the electrical properties of the ultra-thin dendrimer LB films. The electrical properties of the ultra-thin dendrimer LB films were investigated by studying the current-voltage characteristics of metal/dendrimer LB films/metal (MIM) structure. And rectifying behavior of the devices was occurred in applied field.

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공중합체 LB막의 제작과 유기가스 반응 특성 (Fabrication and organic gas response characteristics of the copolymer LB films)

  • 신훈규;최용성;장정수;권영수
    • E2M - 전기 전자와 첨단 소재
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    • 제9권2호
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    • pp.180-187
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    • 1996
  • The use of preformed copolymers and their cross-linking have been attempted in order to improve the intrinsic fragility of monolayers and Langmuir-Blodgett (LB) films and to make their technological applications. It has shown that an imidization followed a polyion-complexation can stabilize the LB films against heat and solvents. And, when the polymer structure was properly designed, concurrent removal of the alkyl tails together with imide formation could be accomplished. In this paper, the monolayers of the polymers which were polyion-complexed with PAA at the air-water interface can be transferred onto solid substrates such as porous fluorocarbon membranes filter and quartz crystal microbalance. The properties of the monolayers and the LB films will be discussed by .pi.-A isotherms, FT-IR, DSC, deposition ratio, QCM, and SEM. In addition, it was attempted to investigate the response characteristics of polymer LB films to the organic gases by the use of QCM.

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Climatological Estimation of Sea Surface CO2 Partial Pressure in the North Pacific Oceans by Satellite data

  • Osawa, Takahiro;Akiyama, Masatoshi;Sugimori, Yasuhiro
    • 대한원격탐사학회:학술대회논문집
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    • 대한원격탐사학회 1999년도 Proceedings of International Symposium on Remote Sensing
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    • pp.237-242
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    • 1999
  • As one of the key parameters to determine $CO_2$ flux between air - sea interface, it is quite important to know p$CO_2$, which has involved much uncertainty, mainly due to the complex variations of sea surface p$CO_2$ and the paucity of samples, made in ocean. In order to improve the interrelationship between partial pressure (p$CO_2$) and different physical and biochemical parameters in global sea surface water, a new empirical relation is established to correlate and parameterize p$CO_2$ in the mixed layer using the data from recent WOCE cruises. Meanwhile, by new empirical relation, abundant historical hydrographic and nutrients ship data, Levitus data set and NOAA/AVHRR(SST), p$CO_2$ have been accumulated and applied. Then effort has to be made fur promotion of this study to correlate and parameterize p$CO_2$ in the mixed Layer with different physical and biochemical parameters. and further attribute this huge historical data sets and NOAA/AVHRR(SST) data to estimate p$CO_2$. In this paper we analyzed more interrelationship between the model and ship/satellite data set. Finally, the inter-annual variations of p$CO_2$ in sea are presented and discussed.

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