• 한국신재생에너지학회:학술대회논문집
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• 2010.11a
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• pp.76.1-76.1
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• 2010

Recently, many efforts to solve the durability problem of PEM fuel cell are carried on constantly. However, despite this attention, durability researches of gas diffusion layer (GDL) are not much reported yet. Generally, GDL of PEM fuel cell experiences three external attacks, which are dissolution of water, erosion of gas flow, corrosion of electric potential. In this study, among these degradation factors, carbon corrosion of electric potential was focused and investigated with accelerated carbon corrosion test. Through the test, it is confirmed that carbon corrosion occurred at GDL, and corroded GDL decreased a performance of operating fuel cell. The property changes of GDL were measured with various methods such as air permeability meter, pore distribution analyzer, thermo gravimetric analyzer, and tensile stress test to discover the effects of carbon corrosion. Carbon corrosion caused not only loss of weight and thickness, but also degradation of mechanical strength of GDL. In addition, to analysis the reason of GDL property changes, a surface and a cross section of GDL were observed with scanning electron microscope. After 100 hours test, the GDL showed serious damage in center of layer.

• The Journal of Engineering Geology
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• v.3 no.2
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• pp.203-214
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• 1993

Underground Injection Control regulations for Class I injection wells require that the vertical dufusion be considered as a mechanism for transport of contaninants in evaluating containment Due to the low permeability in the confining aquitard, the movement of contaminants over the long term is controlled by the molecular diffusion. The movement can be predicted, using the Fick' S second law of diffusion. The diffusion coefficient in Fick' s law has been determined experimentally in this study. Instantaneous injection of $^{51}Cr$ was used to trace the distribution of Cr(VI) in soil plugs and an analytical solution was applied to calculate the diffusion coefficients. This study shows the effect of environmental factors, such as temperature, chloride concentration, applied amount of $^{51}Cr$, and bulk density of injection formations on diffusion of Cr(VI)

• Journal of the Korean Society of Clothing and Textiles
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• v.34 no.3
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• pp.518-528
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• 2010

This study analyzes the work environment and the work clothes wearing conditions of shipyard painters. In addition to this, three types of experimental painting work clothes were evaluated by painters in terms of the material performance and wearing functions. The findings on the harmful painting work environmental factors were organic solvents, noise, heavy dust, high temperatures, and noxious fumes. The body parts damaged during painting operations were the skin, arms, whole body, and face. In general, the satisfaction with the wearing performance of work clothes for painting was low especially in regards to sweat absorbency, sweat permeability, body protection, covering, and the work motion suitability. The satisfaction with the wearing sense of painting working clothes (regardless of the type of material) was high in the order of movement comfort> sensual comfort> physiological comfort. The satisfaction in overall comfort according to the types of material was high in the order of nylon> SMS nonwoven fabric> SF nonwoven fabric.

• Journal of the Korean Society of Clothing and Textiles
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• v.34 no.8
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• pp.1378-1391
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• 2010

This study examines the wearing conditions of working clothes according to the working environment and working processes at machinery, automobile, shipbuilding industry sites. It also investigates the relationship between the wearing sense of working clothes and the overall comfort according to work processes. The hazardous working environment was high in the order of the shipbuilding industry, machinery, and automobiles. The findings on the harmful overall work environmental factors were the noise, heavy dust, and noxious fumes, respectively. In general, the satisfaction with the wearing performance of working clothes was low especially with regard to sweat absorbency, sweat permeability, body protection and covering, and the work motion suitability. In respect of the correlation between the overall comfort and the wearing sense of working clothes, the satisfaction was decreased in the order of movement comfort, sensual comfort, and physiological comfort.

• Fashion & Textile Research Journal
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• v.16 no.1
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• pp.153-159
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• 2014

This study evaluates the changes of the subjective hand, preference, comfort and mechanical properties of tricot based artificial suede made from sea-island type micro fibers according to raising condition. The subjective hand and the preference of raised suede for jacket were rated by the 20's and 30's women experts according to raising cycles. Comfort properties were evaluated by air permeability, water vapor transmission, and thermal transmission. Mechanical properties were measured by the KES-FB system. The subjective hand of artificial suede was categorized into three hand factors: smoothness, warmness and thickness. Smoothness, warmness and thickness perception increased with raising cycles which affected hand preference and luxuriousness perception. The thickness and wale density of suede increased with the number of raising. Suede became more compact and less pliable and less stretchable due to increased fabric thickness; in addition, the surface of suede became smoother and compressive since the surface evenness of suede improved with smaller fiber fineness and an increased amount of naps covered the base fabric. Furthermore, water vapor transmission decreased and thermal insulation increased. The best raising conditions for artificial suede was four cycles in which artificial suede was preferred without changes in physical properties.

• Environmental Engineering Research
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• v.11 no.5
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• pp.241-249
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• 2006

A mathematical model is described for the prediction of convective upward transport of an organic solvent driven by evaporation at the surface, which is known as the major transport mechanism in the in-situ photolysis of a soil contaminated with 2,3,7,8-tetrachlorodibenzo-p-dioxin(TCDD). A finite-element model was proposed to incorporate the effects of multiphase flow on the distribution of each fluid, gravity as a driving force, and the use of hysteretic models for more accurate description of k-S-p relations. Extensive numerical calculations were performed to study fluid flow through three types of soils under different water table conditions. Predictions of relative permeability-saturation-pressure (k-S-p) relations and fluids distribution for an illustrative soil indicate that hysteresis effects may be quite substantial. This result emphasizes the need to use hysteretic models in performing flow simulations including reversals of flow paths. Results of additional calculations accounting for hysteresis on the one-dimensional unsaturated soil columns show that gravity affects significantly on the flow of each fluid during gravity drainage, solvent injection, and evaporation, especially for highly permeable soils. The rate and duration of solvent injection also have a profound influence on the fluid saturation profile and the amount of evaporated solvent. Key factors influencing water drainage and solvent evaporation in soils also include hydraulic conductivity and water table configuration.

• Reproductive and Developmental Biology
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• v.38 no.1
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• pp.1-8
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• 2014

Artificial insemination technique has been contributed immensely for production of livestock worldwide as a critical assisted reproductive technique to preserve and propagate excellent genes in domestic animal industry. In the past decade, methods for semen preservation have been improved mostly in liquid preservation method for boar semen and freezing method for bull semen. Among many factors affecting semen quality during preservation, reactive oxygen species, produced by aerobic respiration in sperm for survival and motility, are unfavorable to sperm physiology. In mammalian cell as well as in the sperm, antioxidant system plays a role in degradation of reactive oxygen species. Magnetized water forms smaller stabilizing water clusters, resulting in high absorption and permeability of the cell for water, implicating its application for semen preservation. Therefore, this review focuses on preservation methods of boar and bull semen with respect to improvement of extender and reduction of reactive oxygen species by using magnetized water and supplementation of antioxidants.

• Geomechanics and Engineering
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• v.12 no.1
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• pp.35-52
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• 2017

In order to evaluate the grouting effects of water-rich fault in tunnels systematically, a feasible and scientific method is introduced based on the extension theory. First, eight main influencing factors are chosen as evaluation indexes by analyzing the changes of permeability, mechanical properties and deformation of surrounding rocks. The model of evaluating grouting effects based on the extension theory is established following this. According to four quality grades of grouting effects, normalization of evaluation indexes is carried out, aiming to meet the requirement of extension theory on data format. The index weight is allocated by adopting the entropy method. Finally, the model is applied to the grouting effects evaluation in water-rich fault F4-4 of Qingdao Jiaozhou Bay Subsea Tunnel, China. The evaluation results are in good agreement with the test results on the site, which shows that the evaluation model is feasible in this field, providing a powerful tool for systematically evaluating the grouting effects of water-rich fault in tunnels.

• Korean Journal of Veterinary Research
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• v.26 no.1
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• pp.139-147
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• 1986

In order to clarify the pathogenesis of perirenal edema, pigs and rabbits were administered with oxalate and nitrate, with oxalate nitrate and glycolic acid, with oxalate, nitrate and ascorbic acid and with oxalate, nitrate and calcium, respectively. The results obtained are summarized as follows; The pigs and rabbits administered with oxalate and nitrate with oxalate, nitrate and glycolic acid and with oxalate, nitrate and ascorbic acid, respectively, were not showed perirenal edema despite of observing the abundant oxalate crystals in the proximal convoluted tubles. But pigs and rabbits administered with oxalate, nitrate and calcium were histopathologically showed perirenal edema similar to those of pigs fed Amaranthus retroflexus. Therefore, author considered that oxalate, nitrate and calcium are main factors to cause perirenal edema. It was regarded that perirenal edema in pigs was caused by the reciprocal reactions of those materials including oxalate, nitrate and calcium which may produce vascular damage, decreased osmotic pressure by hypoproteinemia and increased vascular permeability in kidney, rather than the mechanical obstructions by the oxalate crystals in the proximal convoluted tubule.

• Proceedings of the Korean Geotechical Society Conference
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• 2006.03a
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• pp.970-979
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• 2006

Construction of underground structure requires higher standard of planning and design specifications than in surface construction. However, high construction cost and difficult working environment limit design level and construction quality. One of the most sensitive factors to be considered are infiltration and external pore-water pressures. Development of pore-water pressure may accelerate leakage and cause deterioration of the lining. In this paper, the development of pore-water pressure and its potential effect on the linings are investigated using physical model tests. A simple physical equipment model with well-defined hydraulic boundary conditions was devised. The deterioration procedure was simulated by controlling both the permeability of filters and flowrate. Development of pore-water pressure was monitored on the lining using pore pressure measurement cells. Test results identified the mechanim of pore-water pressure development on the tunnel lining which is the effect of deterioration of drainage system. The laboratory tests were simulated using coupled numerical method, and shown that the deterioration mechanism can be reproduced using coupled numerical modelling method.