• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2010년도 춘계학술대회 초록집
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• pp.172.2-172.2
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• 2010

This study was carried out in order to reduce the installation expense of heating system for greenhouse comparing to geothermal heat pump and develope the coefficient of performance (COP) for a heat pump. For getting plenty of heat flux from geothermal energy. Surface water in river channel was used for getting a lots of geothermal heat by penetrating water through underground soil layer of the river bank that make heat transmission to passing water. The range of water temperature after the process of Ground filtration is 13~18 degrees celsius which is very similar to low heat source of geothermal heat pump system and the plenty amount of heat source from that make the number of geothermal heat exchanging hole and the expense for geothermal heat exchanger construction reduced. Drainage well is also used for returning filtration water to the aquifer that keep the water good recirculation from losing geothermal heat and water resource. For the COP improvement of Heat pump, thermal storage tank with separating insulation plate according to the temperature difference make the COP of Heat pump that is similar to thermal storage tank with diffuser. Developed thermal storage tank make construction expense cheaper than customarily used one's. and that sand filter and oxidation sand (FELOX) are going to be used for improving ground filtration water quality that make heat exchanger efficiency better. All above developed component skill are going to be set on the Ground filtration water source heat pump system and applied for medium, large scale for protected greenhouse in riverside area and on-site experiment is going to do for optimizing the heating system function and overcome the problem happening in the process of on-site application afterward.

• 한국방재안전학회논문집
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• 제9권2호
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• pp.63-75
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• 2016

안전한 수돗물 공급을 위해 정수처리장부터 최종 단계인 수도꼭지까지 일정 수준 이상의 잔류염소농도가 유지되어야 한다. 하지만 국내 문헌에 따르면 상수공급의 전체 과정 중에 30-60%의 잔류염소가 소실되고, 이에 대한 주요 원인으로 정수처리 과정에서 염소 사용량 감소 추세, 급수배관 내에서 염소분해 손실, 여름철의 높은 온도에 의한 잔류염소 분해 속도 증가, 급수배관의 노후화에 따른 잔류염소 손실, 저수조 내 저장 시 잔류염소 감소 발생 등이 파악되었다. 이러한 이유로 저수조를 거치는 급수 방식의 경우 최종 수도꼭지의 잔류염소 농도가 기준치보다 낮아질 개연성이 높고, 용량과 체류시간을 단순히 고려하는 기존의 저수조 설계 방식으로 인해서 수돗물 공급의 안전성에 대한 우려가 존재한다. 이의 개선 방안 도출을 위해서 본 연구에서는 저수조 내 잔류염소 감소에 관여하는 주요 기작들인 수체 내 잔류염소 분해, 벽체 표면 흡착, 그리고 증발에 의한 물질전달을 수학적으로 묘사하는 공식들과 계수 값들을 문헌을 통해서 획득하고, 일반적 저수조 조건에서 모델 시뮬레이션을 수행하였다. 그 결과 저수조에 유입되는 수돗물 내 유기물 농도, 수돗물이 저수조에 유입되는 수리학적조건(난류 정도), 그리고 저수조 벽체 표면 재질의 흡착능 등이 저수조 내 잔류염소 감소에 주요 영향 인자들임을 알 수 있었다. 본 연구에서 획득된 결과들은 잔류염소 감소를 최소화하여 안전한 수돗물 공급을 가능하게 하는 새로운 저수조 설계기법이나 기술 개발에 유용하게 활용될 것이다.

• 대한기계학회논문집A
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• 제27권12호
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• pp.2039-2046
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• 2003

Storage tank filled with fluid has unique dynamic characteristics compared to general structures, due to the interaction between fluid and structure. The oscillation of the fluid surface caused by external forces is called sloshing, which occurs in moving vehicles with contained liquid masses, such as trucks, railroad cars, aircrafts, and liquid missles. In this study, the evaluation method for the reduction of sloshing, the optimized size and location of wing and diaphragm baffles are suggested based on the experimental results. The experimental device can simulate the translation motion. A rectangular tank and various baffles are fabricated to study on the sloshing characteristics. The forces measured using the load cell at tank wall and those are compared with each other through the Fourier transformation for various conditions. The study of the sloshing of the rectangular tank equipped with baffles is conducted under the same conditions with non-baffled rectangular tank experiment. From the experimental results, the sloshing reduction effect by the baffles is observed. In conclusion in case of diaphragm baffles, the optimized size ratio of the width of baffle to the water height is 0.44 and the installation location has no effect to the damping of sloshing. In case of wing baffles, the optimized size ratio of the width of baffle to the length of a rectangular tank is 0.1 and the optimized location ratio of the baffle to the water height is 0.9.

• International Journal of Air-Conditioning and Refrigeration
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• 제10권1호
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• pp.31-39
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• 2002

Microencapsulated pcm (MPCM) particles are mixed with distilled water and utilized to evaluate its characteristics and performance as a thermal storage medium transporting heat. For the present study, tetradecane ($C_14$$H_30$, $T_m$=5.5$^{\circ}C$) is capsulated in the core, coated with the melamine for their surface. The size of particles is well-controlled under 10$\mu$m in the process of in-situ polymerization with melamine-formaldehyde resin. For the experiment, the concentractions of slurries are prepared for 20 wt%, 30 wt%, and 40 wt%. The results are compared with those of water and 100% tetradecane oil. The pure water and tetradecane start solidifying within 20 minutes after introducing cooling water into the thermal storage tank whose flow rates are varied by 125 cc/min, 250 cc/min, and 500 cc/min. However, MPCM slurries are required relatively longer period of time for their phase change than pure phase change materials. That is, the entrained MPCM particles restrict their heat transfer in terms of natural convection and conduction to them.

• 한국펄프종이공학회:학술대회논문집
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• 한국펄프종이공학회 1999년도 Proceedings of Pre-symposium of the 10th ISWPC
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• pp.61-69
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• 1999

Contaminants such as fatty acids, triglycerides, resin acids and foam collected from a high yield sulfite weak liquor storage tank lowered the water surface tension and reduced inter-fibre bonding but also tended to benefit sheet opacity. Some common wet end additives such as defoamers and dispersants gave similar results. Lignosulfonate and naphthalene sulfonate showed little if any negative effect on both surface tension and sheet strength properties. Among the natural wood extractives. fatty acids were identified to be most detrimental followed by triglycerides and then resin acids. In order to alleviate the detrimental impact of these contaminants, membrane separation, air floatation and ozone treatment were carried out on paper machine white water samples. The effect of these treatments on removal of fatty and resin acids was quantified by a GC-Mass analysis. Reverse osmosis with a 1000 molecular weight cut off membrane failed to totally reject fatty and resin acids, but markedly reduced losses of sheet properties due to contaminants. Ozone treatment resulted in a significant increase of the surface tension and air floatation was considered to be a practical and useful method for removing fatty and resin acids from the machine white water.

• 한국에너지공학회:학술대회논문집
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• 한국에너지공학회 2004년도 춘계 학술발표회 논문집
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• pp.219-224
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• 2004

The present study was to investigate the heat transfer enhancement effect of coil wire fins in an ice storage system. For the two cases of tubes with internal brine flows, a finned tube with coil wires on its outer surface and a smooth tube, the rates of ice layer were tested and compared for both the icing processes. The coil fins were made of a stainless steel wire with a dia. of 2.0(mm), and the coil had an outer dia. of 10(mm) and a helix angle of 60($^{\circ}$). The experimental results showed that the coil fins could substantially reduce the thermal resistance of the ice layer, and enhance the heat flow rates between the water in the storage tank and the brine. The ice storing time was found to be shortened by 13(%) for the coil fins to get the same amount of ice layer that was built on the smooth tube wall for 10 hours of operation when the same thermal conditions were provided.

• 한국태양에너지학회 논문집
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• 제31권5호
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• pp.41-46
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• 2011

In the present work, a new freeze protection method has been proposed for a natural circulation system of solar water heater. Though electrothermal wire is popularly used for the purpose, there are freezing troubles by wire cut-off and excessive electric power consumption. In the experimental device, hot water in a storage tank was circulated by a small pump and used to heat the outdoor pipes if the cold water pipe surface temperature falls lower than a set point. As a result, It was observed that there was no hot water waste while the solar water heating system operated without freeze and burst.

• ALGAE
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• 제37권2호
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• pp.149-161
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• 2022

Noctiluca scintillans is a heterotrophic dinoflagellate that causes red-colored oceans during the day (red tides) and glowing oceans at night (bioluminescence). This species feeds on diverse prey, including phytoplankton, heterotrophic protists, and eggs of metazoans. Thus, many scientists have conducted studies on the ecophysiology of this species. It is easy to cultivate N. scintillans at a scale of <1 L, but it is difficult to cultivate them at a scale of >100 L because N. scintillans cells usually stay near the surface, while prey cells stay below the surface in large water tanks. To obtain mass-cultured N. scintillans cells, we developed an automatic system for cultivating N. scintillans on a scale of 100 L. The system consisted of four tanks containing fresh nutrients, the chlorophyte Dunaliella salina as prey, N. scintillans for growth, and N. scintillans for storage, respectively. The light intensities supporting the high growth rates of D. salina and N. scintillans were 300 and 20 µmol photons m^-2 s^-1, respectively. Twenty liters of D. salina culture from the prey culture tank were transferred to the predator culture tank, and subsequently 20 L of nutrients from the nutrient tank were transferred to the prey culture tank every 2 d. When the volume of N. scintillans in the predator culture tank reached 90 L 6 d later, 70 L of the culture were transferred to the predator storage tank. To prevent N. scintillans cells from being separated from D. salina cells in the predator culture tank, the culture was mixed using an air pump, a sparger, and a stirrer. The highest abundance of N. scintillans in the predator culture tank was 45 cells mL^-1, which was more than twice the highest abundance when this dinoflagellate was cultivated manually. This automatic system supplies 100 L of N. scintillans pure culture with a high density every 10 d for diverse experiments on N. scintillans.

• 한국해양공학회지
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• 제24권5호
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• pp.31-38
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• 2010

The Floating storage and re-gasification unit (FSRU), which has large cargo storage tanks, is a floating liquefied natural gas (LNG) import terminal. The sloshing motion in tanks that are partially filled with LNG can cause impact pressure on the containment system and affect the global motion of the FSRU. Therefore, the accurate prediction of sloshing motion has been a significant issue in the offshore gas production industry. In this paper, a particle method based on the moving particle semi-implicit (MPS) method proposed by Koshizuka and Oka (1996) has been modified to predict sloshing motion accurately in a rectangular tank with the filling ratio of water. The simulation results, including the violent sloshing of the fluid, were validated by comparison with the original MPS method.

• 한국구조물진단유지관리공학회 논문집
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• 제24권5호
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• pp.126-134
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• 2020

유체 저장 구조물은 지진 시 유체의 출렁임에 의해 동수압이 발생한다. 이 때, 유체의 동수압은 지진의 강도뿐만 아니라 유체 자유수면의 출렁임 높이(sloshing height)에 의해서도 변화한다. 이러한 하중 변화에 영향을 미치는 인자로는 지진파의 형상, 최대지진강도, 유체 저장구조물의 크기, 구조물의 폭, 유체의 높이 등이 있으며, 본 연구에서는 유체높이와 구조물 폭의 비가 유체의 출렁임 특성에 미치는 영향을 규명하고자 한다. 이를 위하여 구조물의 폭이 500mm인 수조에 구조물의 전체 높이 대비 50%인 200mm와 35%인 140mm의 유체를 담아 실지진파를 적용시켜 유체 자유수면의 출렁임 높이를 측정하였다. 또한 수치해석기법 중 하나인 SPH기법을 통하여 실험과 해석의 유사성을 검증하였다. 실험과 해석의 비교를 통하여 유체의 자유 수면이 유사한 형상을 나타냄을 확인하였으며, 이를 바탕으로 SPH기법을 적용하여 유체높이와 구조물 폭의 비를 다양하게 변화시키면서 유체 자유수면의 출렁임 형상을 분석하였다. 이상의 결과를 바탕으로 지진시 유체 자유수면의 최대 높이 및 최소높이를 예측할 수 있는 식을 제안하였으며, 제안식에 의해 예측된 유체 자유수면의 최대 높이 및 최소 높이의 오차는 최대 3% 이내임을 확인하였다.