• 대한기계학회논문집A
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• 제24권1호
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• pp.103-109
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• 2000

A method to measure the crack length in rubbery materials is described. Through dimensional analysis and experiments, an equation is derived to give the crack length as a function of the change of strain energy density in a region remote from the crack. The function is provided in a form of separated terms of loading and material, the validity of which is experimentally proved using separation parameters.

• Environmental Engineering Research
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• 제16권1호
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• pp.35-39
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• 2011

An integrated gasification combined cycle (IGCC) system has been attracting attention due to its increased energy conversion efficiency and ability to treat various carbonaceous materials. IGCC is also expected to play an important role in the future supply of hydrogen energy. The use of a palladium-based membrane to separate the hydrogen from the synthesis gas stream has been intensively studied due to its exceptional hydrogen-separating capability. However, theoretical research on hydrogen separation is still an unfamiliar area in Korea. First-principle density functional theory was applied in this study to investigate the dissociative adsorption of hydrogen onto a palladium surface. The stability of hydrogen on the surface was theoretically evaluated with various adsorption configurations, partial pressures and temperatures. Further theoretical and experimental studies were also suggested to find a more hydrogen-selective material.

• The Journal of the Acoustical Society of Korea
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• 제27권1E호
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• pp.30-34
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• 2008

An improvement to the existing blind signal separation (BSS) method has been made in this paper. The proposed method models the inherent signal dependency observed in acoustic object to separate the real-world convolutive sound mixtures. The frequency domain approach requires solving the well known permutation problem, and the problem had been successfully solved by a vector representation of the sources whose multidimensional joint densities have a certain amount of dependency expressed by non-spherical distributions. Especially for speech signals, we observe strong dependencies across neighboring frequency bins and the decrease of those dependencies as the bins become far apart. The non-spherical joint density model proposed in this paper reflects this property of real-world speech signals. Experimental results show the improved performances over the spherical joint density representations.

• 한국수소및신에너지학회논문집
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• 제1권1호
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• pp.40-47
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• 1989

The sulfur-iodine thermochemical water splitting process of GA(General atomic) cycle was studied to produce hydrogen from water by $H_2-I_2-SO_2$ reactions. The experimental scale was 500g based on iodine. The reaction took 100 minutes, products could be separated two liquid phases due to their density difference:HI solution had a density of 2.39~2.61g/cc, and $H_2SO_4$ solution had 1.37~1.38g/cc. The condition of reaction was when weight ratio of $I_2/H_2O$ was 2/1 resulting in good phase separation and productivity.

• 한국가시화정보학회지
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• 제4권2호
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• pp.81-87
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• 2006

In this paper, we present flow patterns around and performance of an air-flow separator by using the numerical analysis. With this separator, particles of different density are to be separated by using the drag force from the air flow. The low-density particles are designed to be separated by using inhalation through holes on a rotating drum. To obtain the flow informations needed for determining the proper design parameters, we have performed numerical simulations by using a commercial code, ANSYS CFX. Various parameter set was tested and it was found that depending on the design of drums there exist critical parameter set regarding the attachment of light particles on the drum, which is prerequisite for the separation of materials. We present here the possibility of using the present design in separation of particles mixed in the clod for use in recycling.

• Journal of Electrochemical Science and Technology
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• 제1권2호
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• pp.69-74
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• 2010

Methodologies to improve photovoltaic performance of dye-sensitized solar cell (DSSC) are reviewed. DSSC is usually composed of a dye-adsorbed $TiO_2$ photoanode, a tri-iodide/iodide redox electrolyte and a Pt counter electrode. Among the photovoltaic parameters of short-circuit photocurrent density, open-circuit voltage and fill factor, short-circuit photocurrent density is the collective measure of light harvesting, charge separation and charge collection efficiencies. Internal quantum efficiency is known to reach almost 100%, which indicates that charge separation occurs without loss by recombination. Thus, light harvesting efficiency plays an important role in improvement of photocurrent. In this paper, technologies to improve light harvesting efficiency, including surface area improvement by nano-dispersion, size-dependent light scattering efficiency, bi-functional nano material, panchromatic absorption by selective positioning of three different dyes and transparent conductive oxide (TCO)-less DSSC, are introduced.

• 한국초전도ㆍ저온공학회논문지
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• 제23권3호
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• pp.10-13
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• 2021

The method of removing micro-plastics from sea water has been developed using electro-magnetic force. Plastics are difficult to decompose and put a great load on the marine environment. Especially a plastic with a size of 5 mm or less is defined as micro-plastic and are carried by ocean currents over long distances, causing global pollution. These are not easily decomposed in the natural environment. The Lorentz force was generated in simulated sea water and its reaction force was applied to the micro-plastic to control their motion. Lorentz force was generated downward and the reaction force to the plastics was upward. The plastic used in the experiment was polystyrene with a diameter of 6 mm, and the density was 1.07 g/cm³. The polystyrene sphere levitated at the current density of 0.83 A/cm² and the external field of 0.87T. The particle trajectory calculation was also made to design separation system using superconducting magnet.

• 한국주거학회논문집
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• 제26권2호
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• pp.21-28
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• 2015

The purpose of this paper is to estimate and deduct appropriate Hanok type within Suwon Hwaseong Fortress in which formula Hanok type has not remained. To do so, urban change according to chronology is analyzed and architectural aspect of transition is collected. By using geographic information in Suwon Hwaseong Fortress, present urban structural density, status of architecture and chronological aspect of transition in one-story buildings is surveyed. Through these data, appropriate Hanok form and density to the area is suggested. As a result, Hanok with two or more stories is economically suitable because its average plottage is excessively narrow. And back trowelling is desirable to construct walls in some concentrated areas with Hanok through arrangement of construction. Also in the other building sites, Hanoks are formed by a standard for separation to the property line. However it is necessary that exist standard about separation of property line is institutionally alleviated.

• 대한화학회지
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• 제39권7호
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• pp.524-529
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• 1995

pH 1에서 15-crown-5(SGBM)을 결합시킨 silica gel를 고정상으로 하는 액체 크로마토그래피을 이용하여 혼합 금속이온 용액으로부터 금속이온들의 분리효율을 결정하였다. 여러가지 SGBM-금속이온들간의 결합상수 및 분리인자들을 측정한 결과 그 순위는 Li(Ⅰ) < Sr(Ⅱ) < Na(Ⅰ) < Cu(Ⅱ) < Mg(Ⅱ) < K(Ⅰ) < Ca(Ⅱ) < Bi(Ⅲ) < Sb(Ⅲ)로 나타났다. 이러한 사실은 금속이온의 크기 효과 및 전자 밀도 효과에 의해서 결정됨을 알 수 있었으며, 또한 알칼리, 알칼리 토금속이온 및 $Cu^{2+}$이 혼합된 용액에서 $Sb^{3+}$의 분리효율이 다른 이온들에 비해서 훨씬 좋게 나타남을 알았다.

• 자원리싸이클링
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• 제16권5호
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• pp.13-18
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• 2007

폐콘크리트를 재활용하기 위하여 파쇄과정과 입도조절과정을 거쳐서 생산된 재생골재에는 모르타르나 시멘트페이스트가 많이 부착되어 있어 밀도가 낮고 흡수율이 높아 구조용 골재로 사용할 수 없는 실정이다. 그러나 생산된 재생골재 내에는 많은 양의 콘크리트용 재생골재가 포함되어 있으며 이들을 비중선별방법 중 중액선별을 통해 선별하여 콘크리트용 1종 재생골재를 약 45%정도를 생산할 수 있었다.