• 한국유체기계학회 논문집
• /
• 제17권2호
• /
• pp.41-47
• /
• 2014

Experimental results are given for the vertical motion of water in the water chambers for wave energy converter aligned along the wave propagation direction in order to avoid the impulsive wave forces. This paper mainly focuses on the property of the amplitude of the vertical motion of the water surface in the chambers. The amplification has been investigated by dimensionless parameters of wave period to resonance period ratio of the U-shaped oscillation, $T/T_r$, chamber size to wave length ratio, l/L, water depth to wave length ratio, h/L, amplitude of up-down motion of water particles to draft of the front wall ratio, ${\zeta}/D$. It has been shown that l/L should be less than 0.1 and as $T/T_r$ approaches unity the up-down of the water in the chambers is amplified. Also, the structure of the walls which form th water chambers has been examined roughly. It is deduced that the chambers set on both sides of the hull of a single-point moored floating vessel is preferable to those set along a fixed structure such as breakwaters.

• 한국해양공학회지
• /
• 제36권1호
• /
• pp.21-31
• /
• 2022

In recent years, various studies have been conducted on oscillating-water-column-type wave energy converters (OWC-WECs) with multiple chambers with the objective of efficiently utilizing the limited space of offshore/onshore structures. In this study, a numerical investigation based on a numerical wave tank was conducted on single, dual, and triple OWC chambers to examine the hydrodynamic performances and the energy conversion characteristics of the multiple water columns. The boundary value problem with the Laplace equation was solved by using a numerical wave tank based on a finite element method. The validity of the current numerical method was confirmed by comparing it with the measured data in the previous experimental research. We undertook a series of numerical simulations and observed that the water column motion of sloshing mode in a single chamber can be changed into the piston motion of different phases in multiple OWC chambers. Therefore, the piston motion in the multiple chambers can generate considerable airflow at a specific resonant frequency. In addition, the division of the OWC chamber results in a reduction of the time-dependent variability of the final output power from the device. As a result, the application of the multiple chambers leads to an increase of the energy conversion performance as well as a decrease of the variability of the wave energy converter.

• 설비공학논문집
• /
• 제8권1호
• /
• pp.37-44
• /
• 1996

Water hammer pressure waves were measured in a simplified water piping system with and without arresters and air chambers by the operations of the solenoid valve. Experiments were performed to investigate the effects of the location of the arresters and the effects of the volume of the air chambers on maximum and minimum water hammer pressures and wave frequency for various flow rates.

• International Journal of Naval Architecture and Ocean Engineering
• /
• 제9권3호
• /
• pp.239-245
• /
• 2017

As a new technical approach, wave energy converter by using vertical motion of water in the multiple water chambers were developed to realize actual wave power generation as eco-environmental renewable energy. And practical use of wave energy converter was actually to require the following conditions: (1) setting up of the relevant device and its application to wave power generation in case that severe wave loading is avoided; (2) workability in installation and maintenance operations; (3) high energy conversion potential; and (4) low cost. In this system, neither the wall(s) of the chambers nor the energy conversion device(s) are exposed to the impulsive load due to water wave. Also since this system is profitable when set along the jetty or along a long floating body, installation and maintenance are done without difficulty and the cost is reduced. In this paper, we describe the system which consists of a float, a shaft connected with another shaft, a rack and pinion arrangement, a ratchet mechanism, and rotary type generator(s). Then, we present the dynamics model for evaluating the output electric power, and the results of numerical calculation including the effect of the phase shift of up/down motion of the water in the array of water chambers aligned along the direction of wave propagation.

• 인간식물환경학회지
• /
• 제23권1호
• /
• pp.15-21
• /
• 2020

In this study, we compared efficiency of different aquatic plants in removing indoor pollutants and examined their potential to purify indoor air. Two liter of water in chamber was used as the control, while the other chambers containing water lettuce (Pistia stratiotes), water hyacinth (Eichhornia crassipes), and water coin (Hydrocotyle umbellata) were used as treatment groups. Temperatures inside all the chambers were maintained between 20 ℃ and 23 ℃. Humidity in the chambers with aquatic plants increased by 30% and 50% control respectively. The removal of formaldehyde per unit leaf area was examined in each aquatic plant. It turned out that water hyacinth removed the highest amount of formaldehyde, followed by water lettuce and water coin. Both water hyacinth and water lettuce increased the amount of removal of formaldehyde until the end of the experiment. In the case of airborne dust (PM 10) and fine dust (PM 2.5), water coin, which had the highest number of leaves, removed more PM 10 and PM 2.5 than the other aquatic plants, with statistically significant difference. In addition, both water coin and water hyacinth smoothly opened and closed stomata before and after the experiment. Consequently, as the aquatic plants were effective in controlling humidity and removing pollutants, they can be used as air purifying plants.

• 대한토목학회논문집
• /
• 제26권5B호
• /
• pp.459-467
• /
• 2006

본 연구에서는 화력발전소 순환수취수로의 유량증가가 취수펌프장 흐름에 미치는 영향을 해석하고 개선하기 위하여 수리 및 수치모형실험을 수행하였다. 수치모형실험결과에 의하면 화력발전소 순환수취수로의 유량이 증가하면 취수로내의 유속과 순환수취수 펌프장의 연직방향와도가 증가하여 순환수취수 펌프장내의 와류발생가능성이 크게 증가하는 것을 알 수 있었다. 수리모형실험을 수행하여 순환수취수펌프장 유입부의 수면 근처 흐름은 거의 균등한 유량 배분이 이루어지고 반면에, 바닥 근처의 흐름은 유량 배분이 균등하게 이루어지지 못하여 취수펌프장내에서 역류현상이 발생하는 것을 밝혀냈다. 삼각형 도류벽을 취수펌프장 유입부에 설치하여 유속분포의 불균일성을 제거할 수 있었고 역류발생문제를 제거하였다.

• 한국수자원학회논문집
• /
• 제38권8호
• /
• pp.631-643
• /
• 2005

신설될 복합화력발전소 취수펌프장 계획안에 대하여 수치 및 수리모형실험을 수행하고 순환수취수펌프운영에 문제를 발생시킬 가능성이 발견되면 개선안을 도출하는 것이 본 연구의 목적이다. 수리모형은 1:20의 크기로 아크릴을 이용하여 제작되었고 2차원 수치모형실험은 RMA2모형을 이용하였다. 수리 및 수치모형실험의 결과를 평가하기 위하여 취수로 및 취수펌프장내 흐름에 대한 평가기준을 설정하였다. 복합화력발전소 취수펌프장의 계획안에 대한 2차원 수치모형실험을 통하여 얻어진 연직방향 와도를 수리모형실험결과와 비교하여 흐름평가기준의 하나인 와류발생 가능성을 평가하였다. 계획안은 취수펌프장내에서 큰 규모의 와류가 발생하여 순환수취수펌프운영에 문제를 발생시킬 수 있을 것으로 판단되었다. 이에 따라서 9개 개선안이 고안되어 수치모의되었다. 9개중 4개의 개선안에 대하여 수리모형실험이 수행되었다. 수리모형실험에 근거하여 4개의 개선안의 하나가 최종개선안으로 제시되었다. 공간적인 제약조건이 있는 순환수취수펌프장 및 취수로 설계의 경우 격벽과 도류벽을 이용하면 순환수취수펌프장의 흐름상황을 개선할 수 있는 것으로 나타났다.

• 한국전기전자재료학회:학술대회논문집
• /
• 한국전기전자재료학회 2000년도 춘계학술대회 논문집 전자세라믹스 센서 및 박막재료 반도체재료 일렉트렛트 및 응용기술
• /
• pp.1-5
• /
• 2000

As the semiconductor devices are miniaturized, the number of the unit cleaning processes increases. In order to processes by conventional RCA cleaning process, the consumption of volume of liquid chemical and DI water became huge. Therefore, the problem of environmental issues are evolved by the increased consumption of chemicals. To resolve this matter, an advanced cleaning process by Electrolyzed Water was studied in this work. The electrolyzed water was made by an electrolysis equipment which was composed of three chambers of anode, cathode, and middle chambers. In the case of electrolyzed water with electrolytes in the middle chamber, oxidatively acidic water of anode and reductively alkaline water of cathode were obtained. The oxidation/reduction potentials and pH of anode water and cathode water were measured to be +l000mV and 4.8, and -530mV and 6.3, respectively. The Si-wafers contaminated with metallic impurities were cleaning with the electrolyzed water. To analysis the amounts of metallic impurities on Si-water surfaces, ICP-MS(Inductively Coupled Plasma-Mass spectrometer) was introduced. From results of ICP-MS measurements, it was concluded that the ability of electrolyzed water was equivalent to that of the conventional RCA cleaning.

• 한국산학기술학회:학술대회논문집
• /
• 한국산학기술학회 2001년도 춘계학술대회 발표논문집
• /
• pp.124-128
• /
• 2001

A present semiconductor cleaning technology is based upon RCA cleaning technology which consumes vast amounts of chemicals and ultra pure water(UPW) and is the high temperature Process. Therefore, this technology gives rise to the many environmental issues, and some alternatives such as functional water cleaning are being studied. The electrolyzed water was generated by an electrolysis system which consists of anode, cathode, and middle chambers. Oxidative water and reductive water were obtained in anode and cathode chambers, respectively. In case of NH$_4$Cl electrolyte, the oxidation-reduction potential and pH for anode water(AW) and cathode water(CW) were measured to be +1050mV and 4.8, and -750mV and 10.0, respectively. AW and CW were deteriorated after electrolyzed, but maintained their characteristics for more than 40 minutes sufficiently enough for cleaning. Their deterioration was correlated with CO$_2$ concentration changes dissolved from air. It was known that AW was effective for Cu removal, while CW was more effective for Fe removal. The particle distributions after various particle removal processes maintained the same pattern. In this work, RCA consumed about 9$\ell$chemicals, while EW did only 400$m\ell$ HCI electrolyte or 600$m\ell$ NH$_4$Cl electrolyte. It was hence concluded that EW cleaning technology would be very effective for eliminating environment, safety, and health(ESH) issues in the next generation semiconductor manufacturing.

• 한국양식학회지
• /
• 제16권4호
• /
• pp.252-256
• /
• 2003

양식장에서 생성되는 어류의 노폐물이나 미섭취되고 남은 사료분은 고농도의 질소와 인을 함유하고 있으나 미처리된 상태로 처리하고 있어 그에 따른 처리방안이 요구된다. 본 연구에서는 기존의 처리공정의 대용으로 생태공학적 처리로서 경제적으로 질소와 인 제거를 위해 실내재배조에 물상추를 적용하였다. 앙식장 배출수 처리를 위한 생물여과상의 처리효율을 향상시키기 위하여 물상추 여과조를 설치하여 다양한 조건하에 시도되었다. 실험 재료인 수초는 물상추를 재배하였고, 6개의 수조(62${\times}$60${\times}$86cm)에 재배조 용량이 80 L가 되도록 채우고 수리학적 체류시간(hydraulic retention time; HRT)을 1, 2, 4, 8일로 하여 운영하였다. HRT 8일인 경우 1차 배출수를 대상으로 하였을 경우 BOD, T-N, T-P의 제거율은 92.8, 79.0 및 93.6%로 각각 나타났다.