• Journal of Korean Society of Coastal and Ocean Engineers
• /
• v.25 no.3
• /
• pp.128-137
• /
• 2013

Due to the global warming and air pollution, interest in renewable energies has increased in recent years. In particular, the crisis of the depletion of fossil energy resources in the near future has accelerated the renewable energy technologies. Among the renewable energy resources, oceans covering almost three-fourths of earth's surface have an enormous amount of energy. For this reason, various approaches have been made to harness the tremendous energy potential. In order to achieve two purposes: to improve harbor water quality and to use wave energy, this study proposed a sea water exchange structure applying an Oscillating Water Column (OWC) wave generation system that utilizes the air flow velocity induced by the vertical motion of water column in the air chamber as a driving force of turbine. In particular, the airflow velocity in the air chamber was estimated from the time variations of water surface profile computed by using 3D-NIT model based on the 3-dimensional irregular numerical wave tank. The relationship of the frequency spectrums between the computed airflow velocities and the incident waves was analyzed. This study also discussed the characteristics of frequency spectrums in the air chamber according to the presence of the structure, wave deformations by the structure, and the power of the water and air flows were also investigated. It is found that the phase difference exists in the time series data of water level fluctuations and air flow in the air chamber and the air flow power is superior to the fluid flow power.

• The Magazine of the Society of Air-Conditioning and Refrigerating Engineers of Korea
• /
• v.33 no.4
• /
• pp.27-30
• /
• 2004

최근 주거환경의 악화와 웰빙의 열풍으로 인해 실내 공기 및 물과 관련된 제품들의 개발이 활발히 일어나고 있다. 본고에서는 공기청정기의 변천사와 기반 연구 및 향후 진행방향에 대하여 논한다. 최근 중국에서의 황사가 연일 매섭게 불어오고 있고, TV나 신문, 잡지 등 매스컴에서는 신축 건물이나 아파트, 공공장소의 실내 공기질의 심각성에 대해 언급하며, 이에 대한 다양한 해결책이 제시되고 있다. 미국이나 일본 등 선진국에서는 이미 실내 공기를 오염시키는 유해가스 및 미생물, 방사성 동위원소 등의 원인물질을 규명하고, 원인물질에 따른 실내 공기 청정화 방법 등을 제시하거나 해결하기 위하여 많은 연구가 이루어지고 있다.(중략)

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.40 no.1
• /
• pp.105-110
• /
• 2020

This study provides a method and data for predicting the flight initiation wind speed of wind-borne debris. From the force equilibrium acting on debris including aerodynamic and inertia forces, the equation for predicting the flight initiation wind speeds are presented. Wind tunnel tests were carried out to provide necessary aerodynamic data in the equation for the debris with various aspect ratios. The proposed equation for flight initiation wind speeds was validated from free flying tests in the wind tunnel. The flights of debris were mostly initiated by slip when width to thickness was less than 10, otherwise overturning were dominant. The actual flight initiation speeds were lower than that of the computed ones. The surface boundary layer flow and the gap between the debris and surface might affect the prediction error.

• Proceedings of the Korea Concrete Institute Conference
• /
• 1993.10a
• /
• pp.91-96
• /
• 1993

본 연구의 목적은 콘크리트의 열화손상을 주는 요인 중 특히 수분의 공급이 충분한 동결융해작용에 대한 영향인자에 대한 실험적 연구이다. 콘크리트의 열화에 영향을 주는 여러 영향인자 중에서 주로 공기량 및 물-시멘트비를 다루었다.

• Electric Engineers Magazine
• /
• v.208 no.12
• /
• pp.24-31
• /
• 1999

인류의 생존을 지켜주는 것은 공기와 물이라 할 수 있다. 이처럼 소중한 공기와 물이 인간의 욕구충족을 위해 인간에 의해 파괴당하고 있다는 사실은 엄연한 현실이며 알면서도 인간 서로가 파괴해가고 있다. 아직도 우리는 지구 이외에 전체의 어느 한곳에도 우리가 이주해 할 수 있는 장소를 발견하지 못하고 있으며 달이나 화성, 목성 등 어느 위성에도 인간이 살 수 있는 징후를 찾지 못하고 있다.

• KOREAN POULTRY JOURNAL
• /
• v.44 no.3
• /
• pp.133-135
• /
• 2012

경기도 용인시 처인구에 위치한 '선돌농장'은 대규모는 아니지만 14년 째 육계를 사육하고 있다. 맑은 물과 좋은 공기와 어우러져 자연의 멋스러움을 그대로 느낄 수 있는 '선돌농장'은 선돌이 농장 초입에 있어 농장이름에 대한 이해를 한 번에 알 수 있었다. 4만수 규모로 연6회전하는 '선돌농장'의 권규식(59세)사장을 만나 농장 운영과 육계산업에 대한 생각을 들어보았다.

• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.37 no.9
• /
• pp.837-845
• /
• 2013

An airlift pump can be used to pump liquids and sediments within itself, which cannot easily be pumped up by a conventional method, by using the airlift effect. This characteristic of the airlift pump can be exploited in a DCFC (Direct Carbon Fuel Cell) so that molten fuel with high temperature may be carried or transported. The basic characteristics of airlift are investigated. A simple system is constructed, where the reservoir is filled with water, a tube is inserted, and air is supplied from the bottom of the tube. Then, water is lifted and its flow rate is measured. Bubble patterns in the tube are observed in a range of air flow rates with the parameters of the tube diameter and submergence ratio, leading to four distinct regimes. The pumping performance is predicted, and the correlation between the supplied gas flow rate and the induced flow rate of water is found.

• Journal of Korean Society on Water Environment
• /
• v.23 no.3
• /
• pp.391-396
• /
• 2007

Dry washing by air and sand to clean dishes was investigated for establishing a dry washing process in a kitchen. Thirty seasonings and foods as dirt markers and fourteen kinds of dishes were used for the experiment, and washing efficiency was evaluated by COD-MN (mg/L). It was found that air dry washing effectively reduced COD-MN of some dirt markers but not effective at all to some dirt markers. It could be also said that dirt markers would not be completely removed by air dry washing. The shape of dishes also affected COD-MN reduction by air dry washing. Sand dry washing showed excellent efficiency on COD-MN reduction. Combination of air and sand dry washing may be necessary to make a dish dry washing system which is completely independent from water.

• Water for future
• /
• v.26 no.1
• /
• pp.71-79
• /
• 1993

Nonlinear characteristics of air pressure variation and wave transformation of a fixed air-chamber structure are discussed theoretically and experimentally. Two analytical methods(method I and II) based on the perturbation method and Green's formula are employed in order to evaluate nonlinearities by the submerged and semi-submerged air-chamber structure. Moreover, an air compression model is newly developed to estimate the dynamic air pressure in the air-chamber inside the structure, assuming the Boyle-Charles's law with adiabatic process in the air pressure variation. Theoretical values of the method I considering evanescent mode waves at an fictious boundary, are in good agreement with those of method II employing the fictious boundary which is not affected by evanescent mode waves. Both theoretical values are shown to agree well with experimental values.

• Air Cleaning Technology
• /
• v.8 no.4 s.31
• /
• pp.34-45
• /
• 1995