• 한국주조공학회지
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• 제2권4호
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• pp.2-8
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• 1982

The behavior of sand and mold at high temperatures was generally agreed to importantly affect the quality of castings made. By changing water content through 2,4,6 and 8%, and bentonite content through 5,7,9 and 11%, specimens have been made according to the respective composition. Specimens have been subjected to hot compressive strength and thermal expansion at 400, 600, 800 and $1000^{\circ}C$ respectively. The results obtained were as follows ; 1. At each temperature, thermal expansion decreased and hot compressive strength increased with the increase in water content. 2. After thermal expansion was peaked at approximately $1000^{\circ}C$ the contraction and maximum hot compressive strength appeared. 3. At each temperature, maximum hot compressive strength appeared 2%, 4,6% and 8% water content for 7%, 9% and 11% bentonite content respectively. 4. When 2% $H_2O$ was added, though bentonite content was increased, hot compressive strength did not rarely change. 5. Until the thermal expansion was completed the required time was 15-18 minutes at $400^{\circ}C$ and $600^{\circ}C$, and 10-13 minutes at $800^{\circ}C$. At $1000^{\circ}C$, the required time was 7-9 minutes in order to gain the maximum expansion, after that, contraction proceeded during 3-4 minutes before expansion was completed.

• 상하수도학회지
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• 제10권2호
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• pp.55-69
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• 1996

Backwashing is one of the most important processes in water treatment. Several models have been utilized to predict minimum fluidization velocity and expansion of media. However, it is not unusual that the actual bahavior of media dose not agree well with the prediction. This study has investigated the applicability of models in predicting the minimum fluidization velocity of sand media. However even the better model has predicted minimum fluidization velocity 1.1 to 1.8 times higher than actual fluidization velocity. The expansion rate of sand media was inspected. It is found that the actual expansion rate was greater than the predicted. In this study condition, use of $d_{10}$ instead of $d_{60}$ was better to predict the expansion of media. On the contrary to the sand media, the actual expansion of anthracite media was less than that predicted. Sometimes it is reported that the dual media has been overflown during backwashing and mixed severely at the interface. It is because the grain size distribution of anthracite has not been selected properly. The numerical values for media expansion found in this study could be referred as the useful data in operating and/or designing filter media.

• 한국해양공학회지
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• 제20권5호
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• pp.9-14
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• 2006

This paper presents an analytical method, application of expansion, mechanical design, and integrated expansion design of subsea insulated pipe-in-pipe (PIP) systems. PIP system consists of a flowline and a casing pipe for the transport of high temperature and high pressure product from the subsea wells. To prevent heat lass from the fiowline, insulation material is applied between the pipes. The fiawline pipe and the casing pipe have mechanical connections through steel ring plate (water stops) and bulkheads. Pipeline expansion is defined by temperature, internal pressure, soil resistance, and interaction force between the flowline and the casing pipe. The results of the expansion analysis, the mechanical design of connection system of the two pipes and tie-in spool design are integrated for the whole PIP system.

• 산업식품공학
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• 제15권2호
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• pp.148-154
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• 2011

사출구 구조가 압출성형의 목적변수인 팽화특성에 영향을 미치는지 알아보기 위하여 사출구의 기하학적 구조를 사출구상수로 산출하여 사출구상수와 수분함량에 따른 팽화특성을 비롯한 비기계적 에너지 투입량, 수분용해지수, 수분흡착지수를 분석하였다. 압출성형 공정변수는 수분함량(20, 25%), 사출구멍의 길이와 직경비(L/D 0.67, 1.67, 2.67), 내벽에서 좁아지는 각(57, $95^{\circ}$)이였다. 비기계적 에너지 투입량은 수분함량 20%, 사출구상수 2.23E-10 $m^3$에서 가장 높은 값을 나타내었다. 수분함량 20%에서 사출구상수가 증가하면, 직경팽화지수와 체적팽화지수는 증가하였다. 한편 수분함량 25%에서 직경팽화지수와 체적팽화지수는 사출구상수의 영향을 받지 않았다. 또한 길이팽화지수는 수분함량이 20%에서 25%로 증가할 때 증가하였으며 직경팽화지수와 음의 상관관계를 나타내었다. 수분흡착지수와 수분용해지수는 사출구상수에 영향을 받지 않았다.

• 한국GIS학회:학술대회논문집
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• 한국GIS학회 1995년도 추계학술대회 발표요약문
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• pp.9-21
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• 1995

계획지원체계는 도시성장관리수단으로 간선시설 시설확장을 이용하는 우리의 능력을 증진시킨다. 이연구는 그러한 계획지원체계 (PEGASUS: 공간도시체계의 생성 및 분석을 위한 계획환경)의 개발계획의 일환으로서 상수도 시설확장모델의 개발에 관한 연구이다. 이 연구는 토지이용과 개발은 간선시설의 수요를 유발하고 간선시설은 토지가 이용되고 개발되는 방향에 영향을 미친다는 전제하에서 시작된다. 상수도 시설 확장은 2 방법으로 해결될 수 있다: 1) 최적통제이론, 2) MINLP 방법. 이 방법들은 각각장단점을 가지고 있다. 이 연구에서는 동적 시설 확장 크기 및 시기를 동시에 결정할 수 있는 MINLP방법이 채택이 되었다. 상수도 관망해석모델과 동적 상수도 시설 최적화 모델이 상수도계획과 토지이용계획의 동적 연관관계를 해결할 수 있다. 상수도 관망해석모델은 생성된 관경의 적정성을 분석하며 동적 상수도 시설 최적화모델은 변화하는 상수도 수요량을 충족할 수 있는 대안을 작성한다. 표준화기법에 의한 비용편익분석은 가장 경제적인 대안을 선정한다. GIS는 필요 상수도 수요량을 산정하고 시설확장모델의 결과를 이용자에게 보여주는데 훌륭한 역활을 할 수 있다.

• Water Engineering Research
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• 제1권1호
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• pp.75-81
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• 2000

The bragg reflection of obliquely incident monochromatic water waves propagating over a sinusoidally varying topography is theoretically investigated in this study. The eigenfunction expansion method is first employed to calculate reflection coefficients of water waves due to depth changes. A reasonable agreement is observed. Obtained reflection coefficients of normally incident waves are compared with laboratory measurements. Reflection coefficients of obliquely incident waves are then calculated. The wavenumber providing the Bragg reflection agrees well with analytical predictions.

• 공업화학
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• 제23권2호
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• pp.143-147
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• 2012

퍼라이트의 팽창은 고온에서 수초안에 이루어지므로 팽창현상을 실험으로 확인이 어려워 이를 해석하기 위한 버블팽창모사가 필요하다. 이를 위해 용융 퍼라이트 내에 매우 작은 미세 버블이 존재하며 수분 증기가 버블 쪽으로 확산되어 버블이 성장하고 퍼라이트가 팽창하는 모델을 세워 팽창모사를 수행하였다. 수분증기의 확산으로 버블이 성장하여 퍼라이트가 팽창될 때 퍼라이트의 동적 온도는 감소하였다. 버블의 동적압력은 퍼라이트 용융상 내에서 수분 증기가 확산함에 따라 초기에는 증가하지만, 버블의 급격한 팽창 이후에는 오히려 감소함을 확인하였다.

• Journal of the korean society of oceanography
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• 제38권3호
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• pp.87-100
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• 2003

The monthly observations of hydrography in the Cheju Strait from September 1995 to June 1998 show that the Cheju Strait is occupied mostly by Tsushima Current Water in winter and coastal waters in summer. In summer, the Yangtze Coastal Water appears in the upper layer and cold water in the lower layer. Especially, the Yellow Sea Bottom Cold Water appears in August 1997, and the clockwise flow of warm water along the northwestern coasts of Cheju Island is disturbed by an eastward expansion of the cold water from the northwest. The cold water expansion seems to be partly associated with strong southeasterly winds. Current measurements in the Cheju Strait suggest that there exists steady eastward barotropic component of about 5 cm/sec, which corresponds to 0.2 Sv barotropic transport in the Cheju Strait. Geostropic transport (baroclinic component) ranges from 0.1 Sv in winter to 0.4 Sv in summer. By adding the barotrophic component of 0.2 Sv, the total transport varies from 0.3 Sv to 0.6 Sv, which is consistent with previous estimations. The transport increase in summer seems to be caused by the expansion of coastal water to the Cheju Strait.

• 한국물환경학회지
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• 제29권6호
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• pp.754-761
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• 2013

Urban floods are usually caused by the lack of drainage capacity. Hence, sewer capacity expansion methodology by replacing small pipes with bigger ones is primarily applied as a flood control measure. However, this approach is often unreasonable because of the costs and time involved. Thus, the installation of underground rainwater storage tanks with the two advantages of flood control and water conservation is proposed. This study compared the effectiveness of flood control by both the sewer expansion methodology and rainwater storage tanks using the Storm Water Management Model. Three cases were simulated in this study. The first case analyzed flood reduction by the storm sewer expansion methodology. The simulation results indicate that the overflow volume from manholes was reduced by 49% with this methodology. The second case analyzed flood reduction by installation of rainwater storage tanks. The simulation results indicate that the overflow volume was reduced by 62%. However, these two cases could not prevent urban floods completely. Hence, the third case analyzed the joint application of the storm sewer expansion methodology and rainwater storage tanks. In this simulation, flooding did not occur. Consequently, the results of this study clearly show that underground rainwater storage tanks are more effective for flood control than capacity expansion of storm sewer. Furthermore, the joint application of these two flood control measures is more effective than their separate application.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2005년도 추계 학술논문 발표대회
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• pp.79-83
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• 2005

In the reinforced concrete structure, Even if speak that water leakage occurrence is no problem to material, there is a lot of reasons construction factor, material damage by behavior structure, properties of matter change by years and water leakage part by environment condition. so, waterproofing technological consideration should be gone ahead. In this research, we will study about stick performance, concrete surface adhesive, damage and blow. we will check all things and test it. The stick expansion type complex of flexible material passed on result of standard. It is conducive to concrete of durability by waterproofing layer performance demobilitation technology on the water leakage structure for solution of problem and repair