• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.35 no.4
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• pp.377-385
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• 2022

Thermal batteries are specialized as primary reserve batteries that operate when the internal heat source is ignited and the produced heat (450~550℃) melts the initially insulating salt into highly conductive eutectic electrolyte. The heat source is composed of Fe powder and KClO₄ with different mass ratios and is inserted in-between the cells (stacks) to allow homogeneous heat transfer and ensure complete melting of the electrolyte. An ideal heat source has following criteria to satisfy: sufficient mechanical durability for stacking, appropriate heat calories, ease of combustion by an igniter, stable combustion rate, and modest peak temperature. To satisfy the aforementioned requirements, Fe powder must have high surface area and porosity to increase the reaction rate. Herein, the hydrothermal and spray drying synthesis techniques for Fe powder samples are employed to investigate the physicochemical properties of Fe powder samples and their applicability as a heat source constituent. The direct comparison with the state-of-the-art Fe powder is made to confirm the validity of synthesized products. Finally, the actual batteries were made with the synthesized iron powder samples to examine their performances during the battery operation.

• Proceedings of the Korean Society of Crop Science Conference
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• 2002.05a
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• pp.73-76
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• 2002

The foods such as rice, peanuts and plums etc. are recognized as a direct way to keep health and to cure diseases based on the theory of that the medicine and foods are from the same source, not just to maintain life, therefore due to this reason, the dietary treatment is currently gathering strength with patients who are suffering from chronic diseases. Especially, 1 trust that the practical application of functional foods and taking medicine must be highly effective in curing diseases or relieving symptoms. In order to produce the superior functional foods by medicinal herbs, we should to make a greater effort to research the harvest time of material, drying and keeping method, and additionally try to develop the standard of food material and various drugs manufacturing continually.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.49 no.4
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• pp.354-357
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• 2004

A simplified technique which cryoprotects zygotic embryos by encapsulation-dehydration was developed for the germplasm conservation of herbaceous peony (Paeonia lactiflora Pall.). The highest survival rate $(85\%)$ was obtained from embryos treated by encapsulation-dehydration. The zygotic embryos were precultured on MS medium containing 0.3mg/L $GA_3$ for 1 day. The precultured embryos were encapsulated in $3\%$ (w/v) alginate beads and immersed for 1 h in MS medium containing 2 M glycerol and 0.5 M sucrose. The encapsulated embryos were dehydrated for 5h by air drying prior to direct immersion in liquid nitrogen. This encapsulation-dehydration method appears to be a promising technique for germplasm cryopreservation of a herbaceous peony.

• Journal of Environmental Impact Assessment
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• v.18 no.6
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• pp.331-346
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• 2009

The serious problem facing two-dimensional finite element hydraulic model is the treatment of wet and dry areas. This situation is encountered in most practical river and coastal engineering problems, such as flood propagation, dam break analysis and so on. Especially, dry areas result in mathematical complications and require special treatment. The objective of this study is to investigate the wet and dry parameters that have direct relevance to model performance in situations where inundation of initially dry areas occurs. Several numerical simulations were carried out, which examined the performance of the marsh porosity method of RMA-2 model to investigate for application of parameters. Experimental channel with partly dry side slopes, straight channel with irregular geometry and Han river were performed for tests. As a result of this study, effectively applied marsh porosity method provide a reliable results for flow distribution of wet and dry area, it could be further developed to basis for extending to water quality and sediment transport analysis.

• Journal of Korean Academy of Fundamentals of Nursing
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• v.14 no.3
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• pp.297-305
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• 2007

Purpose: The purpose of this study was to evaluate knowledge, attitude, and compliance regarding hand hygiene according to the profession of ICU health care providers. Method: Data were collected by questionnaires and by recording of direct observations of 143 health care providers in 4 intensive care units. With SPSS/WIN 12.0 t-test, ANOVA, and ${\chi}^2-test$ were used to analyze the data. Results: The level of knowledge regarding handwashing among the nurses was higher and a more positive attitude was shown compared to physicians. Overall handwashing compliance was low among all ICU health care providers, but nurses had better compliance than any other health care providers and significantly higher frequency for handwashing before care and after care activities. All of professions had lower scores on the appropriate length of time for handwashing and areas that need to be scrubbed. The level for nurses was medium and for physicians, the lowest of all professions. The appropriate agent for handwashing and the method of drying for handwashing compliance was high in all professions. Conclusion: The results suggest that multidisciplinary interventions are needed to develop an environment for appropriate handwashing as well as to reinforce importance of handwashing compliance for health care providers.

• Journal of Korean Society of Forest Science
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• v.99 no.5
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• pp.682-685
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• 2010

Coring has been widely used to measure annual increment in temperate forest ecosystems. This method is attractive because cores can be taken in just one visit. However, the accuracy of this method has not been tested. We expected coring to be less accurate than band dendrometers because of the eccentricity of tree growth. We studied 41 trees at the Long Term Experimental Forest in Mt. Gyebang, which has been monitored with band dendrometers since 1996. We collected two tree cores from the south and north face of each tree, 10 cm below the growth band. Increment cores were measured to 0.01 mm under stereomicroscopy. Annual growth from 1997 to 2006 was 3.2 mm $yr^{-1}$ for Quercus mongolica, 3.5 mm $yr^{-1}$ for Kalopanax septemlobus, and 5.7 mm $yr^{-1}$ for Pinus densiflora. The difference between the two methods was 10% for Q. mongolica, 14% for K. septemlobus, and 4% for P. densiflora. Compaction in the corer and shrinkage during drying decreased diameter increment by 5.6% and 1.0% on P. densiflora, respectively. This study suggests that the two methods for annual increment measurement are very similar, but species specificity should be concerned for direct comparison.

• Polymer(Korea)
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• v.26 no.1
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• pp.128-138
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• 2002

1,3-Bis(2-chloroethyl)-1-nitrosourea (BCNU, Carmustine)-loaded poly(D, L-lactide-co-glycolide) (PLGA, lactide/glycolide mole ratio 75 : 25) microparticles were prepared and fabricated into wafers in an attempt to study the possibility for the treatment of malignant glioma by direct inserting the wafers to the tumor or the cavity remained after surgical resection of the tumor. SEM observation of the microparticles prepared by spray drying method revealed that the microparticles were spherical, i. e. microspheres. Significant reduction of the crystallinity of BCNU encapsulated in PLGA was confirmed by X-ray diffraction and differential scanning calorimetry analyses of the BCNU-loaded PLGA microparticles. Release pattern of BCNU was dependent on several preparation parameters, such as the molecular weight and concentration of PLGA, and initial BCNU loading amount, etc. In vitro release of BCNU was prolonged over 8 weeks with close to zero-order release pattern after initial burst effect. Observations of morphological change of wafers and pH change of release media during release test period confirmed that hydration and degradation of PLGA would be facilitated with an increase of BCNU-loading amount.

• Journal of the Korean Ceramic Society
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• v.56 no.3
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• pp.211-232
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• 2019

Porous ceramics are promising materials for a number of functional and structural applications that include thermal insulation, filters, bio-scaffolds for tissue engineering, and preforms for composite fabrication. These applications take advantage of the special characteristics of porous ceramics, such as low thermal mass, low thermal conductivity, high surface area, controlled permeability, and low density. In this review, we emphasize the direct foaming method, a simple and versatile approach that allows the fabrication of porous ceramics with tailored microstructure, along with distinctive properties. The wet foam stability is achieved under the controlled addition of amphiphiles to the colloidal suspension, which induce in situ hydrophobization, allowing the wet foam to resist coarsening and Ostwald ripening upon drying and sintering. Different components, like contact angle, adsorption free energy, air content, bubble size, and Laplace pressure, play vital roles in the stabilization of the particle stabilized wet foam to the porous ceramics. The mechanical behavior of the load-displacements curves of sintered samples was investigated using Herzian indentations testes. From the collected results, we found that microporous structures with pore sizes from 30 ㎛ to 570 ㎛ and the porosity within the range from 70% to 85%.

• Polymer(Korea)
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• v.26 no.5
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• pp.680-690
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• 2002

Implantable biodegradable wafers were prepared with pamidronate -loaded poly (L-lactide-co-glycolide) (PLGA, 75 : 25 mole ratio by lactide to glycolide, molecular weight : 20000 and 90000 g/mole) by direct compression method for the sustained release of pamidronate to investigate the possibility for the treatment of bone resorption. Pamidronate-loaded PLGA powders were prepared by means of physical mixing and spray drying with the control of formulation factors and characterized by scanning electron microscope and X-ray diffractometer. The pamidronate-loaded PLGA powders fabricated into wafers by direct compression under the constant pressure and time at room temperature. These wafers were also observed for their structural characteristic, release pattern, and degradation pattern. The release rate of pamidronate increased with increasing their initial loading ratio as well as increasing wafer thickness. The molecular weight of PLGA affects the release pattern : the higher molecular weight of PLGA, the faster release rate. It can be explained that the higher viscosity of high molecular PLGA solution at same concentration tends to aggregate PLGA and pamidronate resulting in unstable pharmaceutical dosage form. This system had advantages in terms of simplicity in design and obviousness of drug release rate and nay be useful as an implantable dosage form for the treatment of aural cholesteatoma.

• Proceedings of the Korean Society for Agricultural Machinery Conference
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• 1996.06c
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• pp.701-710
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• 1996

Composting has gained rapid acceptance as a method of recyling relatively dry organic materials such as leaves and brush and , when alternative disposal costs are high, even moist materials such as grass clippings and dewatered sewage sludges. However, as moisture contents rise above 60% , the need for a dry bulking amendment increase the costs of composting , both by direct purchases of amendment and though increased reactor capacity and materials handling requirements. High moisture materials also present increased risks of anaerobic odor formation through reduced oxygen transport (Miller , 1991) . These costs and operational challengers often constrain the opportunities to compost high moisture materials such as agricultural manures. During the last several decades economies of scale in livestock production have been increasing livestock densities and creating manure management challenges throughout the world. This issue is particularly pressing in Korea, where livestock arms typically manage little or no cropland, and the nutrients and boichemical oxygen demand in manure pose a serious threat to water quality. Composting has recently become popular as a means of recycling manure into products for sale off the farm, but bulking amendments (usually sawdust) are expensive designed to minimize bulking agent requirements by using the energy liberated by decompostion. In this context the composting reactor is used as a biological dryer, allowing the repeated use of bulking amendment with several batches of manure.