• Journal of Integrative Natural Science
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• v.16 no.1
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• pp.13-31
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• 2023

The sesarmid crab Muradium tetragonum, inhabiting the mangrove, are considered as a key consumer of litter and thereby play an important role in the detritus food chain and energy flow in the mangrove ecosystem. The present investigation was carried out with objectives to enlighten the reproductive system of Muradium tetragonum through histological and histochemical studies. Histological organization of the testis of M. tetragonum revealed that each testis has a lobular structure consisting of several testicular lobules arranged around the collecting duct. Histology of the deferens of M. tetragonum revealed it to be composed of three-layer of tissues along the entire length:the outer connective tissue, the middle muscular and the inner epithelial layer. Based on the histological architecture these three regions are recognized as proximal vas deferens (PVD), middle vas deferens (MVD) and distal vas deferens (DVD). Histological characteristics of the ovary of M. tetragonum during different phases of ovarian development were studied. Based on the colour changes of the ovary and diameter of the oocytes five stages of ovarian development can be pronounced. Histochemical analysis of the male reproductive tissues of M. tetragonum signifies the secretion of a different biomolecule by specifying their origin in the reproductive tissue and their possible transformation into spermatophores. In the female reproductive tissues, histochemical evaluation envisaged the secretory products during different stages of ovarian development The secretory substances of the spermatheca expound on the significance of its secretion in dehiscing the spermatophore wall and in nourishing as well as protecting the spermatozoa.

• Korean Journal of Environment and Ecology
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• v.26 no.4
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• pp.498-511
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• 2012

Mountainous wetland have many species such as II grade endangered species of wild flora and fauna(Drosera rotundifolia) and environmental indicator species(Utricularia racemosa, Habenaria linearifolia, Parnassia palustris, Molinia japonica, etc.). Accordingly, the mountainous wetlands is very important. However, most mountainous wetlands will disappear by natural or artificial aridness processes. Thus, it needs to manage mountainous wetland for protecting from aridness. This study has found out the wetland status of the environmental ecology and aridness processes moreover, it has suggested ways of improving wetland conservation plan and wetland aridness management plan. According to the results of topography structure survey, Hwaeom wetland's altitude is ranged within 750~810m(87.4%), and slope is less than $10^{\circ}$. There was ideally suited mountainous wetland. However, the water supply(1.6 meters depth and 0.8 meters wide) was built on under the wetland. For that reason, there was concerned about the aridness processes by sweeping away peat layer and dropping the water level. The distribution area of hygrophyte was narrowed to 6.7% whereas, woody plants and xerophytic plants was achieved a dominant position. If it leaves the situation as it is, the mountainous wetland will be developed next succession as forest ecosystem. Therefore, in order to sustain the mountainous wetland from aridness, it is set to the base direction of conservation and management as main schemes. Moreover, we have suggested that setting the vegetation conservation and management area which considering a ecological vegetation characteristics, managing the ecotone vegetation, setting the buffer zone for protection of ecological core areas, protecting the mountainous wetland indicator species and designating the management vegetation. In conclusion, in order to sustain and maintain a soundly wetland ecosystem, it needs to several management of wetlands damage factors. 1) suppression of the excessive groundwater to basin, 2) stabilization of wetland via hydrologic storage, 3) suppression of changing and transforming wetland into forest by succession via management of xerophytic plants.

• Journal of the Korea institute for structural maintenance and inspection
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• v.9 no.4
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• pp.177-186
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• 2005

The latest concrete structure has showed that the deterioration of durability has been increased by the damage from salt, carbonization, freezing & thawing and the others. Therefore, the measures for the concrete which has deteriorated durability have been taken. Among them, it has been often used that surface treatment which cuts off the deterioration factors of durability by protecting the surface of concrete. However, troubles such as fracture and rupture in the repair layer have been reported as time goes by due to the difference between the organic repair material like epoxy and concrete properties. Researchers have been developing the repair material which can cut off the deterioration factors of durability such as $CO_2$ gas, chloride ion and water by making the formation of concrete elaborate through the reaction with calcium ion when the surface improving agent is coated on the concrete. The main ingredient of that is inorganic substance which is the same as the concrete property. This study was evaluated the surface improving agent for permeability, watertightness, air-permeability, chemical resistance and elution resistance. As a result, it has been reported that the surface improving agent improves watertightness and air-permeability by penetration more than 10mm within concrete. Therefore, it is concluded that the surface improving agent developed in this research prevents deterioration of concrete durability when it is coated on the concrete structure.

• Composites Research
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• v.30 no.2
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• pp.84-93
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• 2017

This study investigates thermal and mechanical characterization of environmental barrier coating on the $SiC_f-SiC$ composites. The spherical environmental barrier coating (EBC) powders are prepared using a spray drying process for flowing easily during coating process. The powders consisting of mullite and 12 wt% of Ytterbium silicate are air plasma sprayed on the Si bondcoat on the LSI SiC fiber reinforced SiC composite substrate for protecting the composites from oxidation and water vapor reaction. We vary the process parameter of spray distance during air plasma spray of powders, 100, 120 and 140 mm. After that, we performed the thermal durability tests by thermal annealing test at $1100^{\circ}C$ for 100hr and thermal shock test from $1200^{\circ}C$ for 3000 cycles. As a result, the interface delamination of EBC never occur during thermal durability tests while stable cracks are prominent on the coating layer. The crack density and crack length depend on the spray distance during coating. The post indentation test indicates thermal tests influence on the indentation load-displacement mechanical behavior.

• 한국초전도학회:학술대회논문집
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• v.9
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• pp.343-347
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• 1999

We fabricated a resistive SFCL having a shunt resistor parallel to it in order to bifurcate the transient current at faults. The SFCL consists of a YBCO film coated with an Au layer (10 ${\omega}$ at room temperature), which is to disperse the heat generated at hot spots in the YBCO film, and the 5 ${\omega}$ shunt resistor. The minimum quench current of the SFCL was found to be 12.2 A$_{peak}$. This SFCL successfully controlled the fault current below 23 A$_{peak}$ which is otherwise to increase up to 113 A$_{peak}$. Bifurcation of the current resulted in the temperature rise of the YBCO/Au film 3 times slower than without the shunt, protecting the SFCL at high currents.

• Magazine of the Korean Society of Agricultural Engineers
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• v.16 no.2
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• pp.3420-3429
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• 1974

This study was performed to estimate the daily water consumption for watering livestock and home use, and to organize the water systems in the rural districts of Korea. For these purposes, 560 farms and other 40 urban families were randomly chosen and investigated about their water systems and daily water consumption seasonally from July 20 to August 31, 1973, and other 82 livestock raisers' useful data for watering livestock helped the study to assess the consumption of livestock water and compare it to that of general farms which bred some domestic animals as their sidelines. The results of data showed that the daily consumption of water was varied with the difference of districts and seasons in which the investigations were conducted. The results were summarized as follows. 1. The mean consumption of water for home use was varied with the range of 30.2-48.7 lit./day in summer and 22.4-45.2 lit./day per a person, respectively, in the rural districts, which showed that the water consumption in summer was more than in autumn. 2. The mean consumption of livestock water in the general farms approached to about 15.8-37.1 lit./day per cattle, 3.87-16.45 lit./day per a pig, and 0.19-1.03 lit./day per chicken, but it was slightly reduced in autumn; 10.89-37.09 lit./day per cattle, 3.87-12.63 lit./day per a pig, and 0.06-0.94 lit./day per chicken. The ratio of livestock water consumption to home use amounted to the range of 10-25%. 3. The mean consumption of livestock water used at the livestock raisers amounted to 134 lit./day per dairy cow, 67.4 lit./day per cattle, 43.29 lit./day per a horse, 13.24 lit./day per a pig, 0.438 lit./day per a layer, and 0.177 lit./day per a broiler, which showed that the daily water consumption for larger livestock was about two times as much as the farms, but it was approximately of the same for small ones. 4. The factors affecting the amount of water consumption for home use were statistically analyzed to find the kind of water sources and the class of water systems by the factorial arrangement method to the fundamental experimental unit, Suwon area of 100 of families, in which the former was very significant while the latter was significant. However, the standard of living and their interactions were not significant. 5. Almost 83.24% of the sampled farms used some kinds of wells as their water sources, of which 32.06% was of hard water, and of which 11.l% or 2.6% contained much of iron or organice materials, respectively, examining them by a simple technique of sensibility, 6. The resulting chart of the farm water systems was summarized as Fig. IV-6. Observating the safe distance from contamination sources, the ratio of 42.4% of sampled farms whose water sources were wells, confronted highly to the danger of contamination to their water sources. And other dangerous sources of contamination such as toilets, stalls, and compost heaps were situated nearly to the water sources, and most of them were able to make their spoiled water infiltrated into the ground. Thereafter, it was recommended to develop some protecting methods and to install some suitable faculties to clean water.

• Korean Journal of Food Science and Technology
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• v.36 no.5
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• pp.779-783
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• 2004

New food ingredient was developed to eradicate and protect against re-infection of Helicobacter pylori in fermentation broth of lactic acid bacteria (LAB) showing antimicrobial activity against pathogenic microorganisms such as H. pylori and Listeria monocytogenes. LAB strain CBT SL4 was identified as Pediococcus pentosaceus by 16S rDNA sequencing and its culture broth showed antimicrobial activity of 800 AU/mL against H. pylori in optimized fermentation process. Using thin layer concentration system and spray-typed fluid bed drier system, concentrated powder product showing activity of 12,800 AU/g was harvested. Product showed eradication and protection activities against H. pylori infection on feeding test (50 AU/day) using Mongolian gerbil infection model. After 4 weeks therapy of 8,000 AU/day, ${\Delta}13CO_2$ level (DOB30) decreased about 40% in urea breath test on patient with H. pylori infection. Result show concentrated culture product of P. pentosaceus CBT SL4 has eradicating and protecting activities against H. pylori infection and can be used as food-active ingredient for prevention of gastric and duodenum ulcer caused by H. pylori.

• Progress in Medical Physics
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• v.9 no.3
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• pp.137-141
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• 1998

The purposes of this report are to evaluate whether lead ball and steel ball could be used as protective material of radiation and to acquire physical data of them for protecting 4-10 MV X-ray beams. Lead balls of diameter 2.0～2.5mm or steel balls of diameter 1.5～2.0 mm were filled in an acrylic box of uniform width. An MV radiograph of metal balls in a box were taken to ascertain uniformity of ball distribution in the box. Average density of metal ball and linear attenuation coefficient of metal balls for 4～10 MV X -rays were measured. At the time of measurement of linear attenuation coefficient, Farmer ionization chamber was used and to minimize the scatter effect, distance between the ball and the ionization chamber was 70 cm and field size was 5.5cm${\times}$5.5cm. For comparison, same parameters of lead and steel plates were measured. The distribution of metal balls was uniform in the box. The density of a mixture of lead-air was 6.93g/cm$^3$, 0.611 times density of lead, and the density of a mixture of steel-air was 4.75g/cm$^3$, 0.604 times density of steel. Half-value layers of a mixture of lead-air were 1.89 cm for 4 MV X-ray, 2.07 cm for 6 MV X-ray and 2.16 cm for 10 MV X-ray, and approximately 1.64 times of HVL of lead plate. Half-value layers of a mixture of steel-air were 3.24 cm for 4 MV X-ray, 3.70 cm for 6 MV X-ray and 4.15 cm for 10 MV X-ray, and approximately 1.65 times of HVL of lead plate. Metal balls can be used because they could be distributed evenly. Average densities of mixtures of lead-air and steel-air were 6.93g/cm$^3$, 4.75g/cm$^3$ respectively and approximately 1.65 times of densities of lead and steel. Product of density and HVL for a mixture of metal-air are same as the metal.

• Korean Journal of Environment and Ecology
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• v.23 no.5
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• pp.431-438
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• 2009

The main purpose of this research is to prepare and provide basic materials for the propagational strategy of eelgrass by investigating on the morphological adaptation of Korean Zostera marina to ocean currents. An eelgrass plant mainly consists of rhizome, leaf sheath, leaves and roots. The rhizome is the horizontal stem of the plant that serves as the backbone from which the leaves and roots emerge. The leaf sheath is the bundle at the base of the leaves that holds the leaves together, protecting the meristem, the primary growth point of the shoot. Leaves originate from a meristem which is protected by a sheath at the actively growing end of the rhizome. As the shoot grows, the rhizome elongates, moving across or within the sediment, forming roots as it progresses. The aggregated leaves from the leaf sheath are found to have two cell layers on one side and multiple layers of airy tissues called aerenchyma on the other. The aerenchyma tissues are developed in multi-layered cell structures surrounding the veins which are formed in the leaf sheath. Generative shoots are made of rhizomes, which are circular or ovoidal, stem, and spathe and spadix. The transverse section of rhizome and the stem and central floral axis is found to be circular, ovoid and in the shape of convex respectively, and the vascular bundle, which is a part of transport system, has one large tube in the center and two small tubes on both sides. The layers of collenchyma cells numbered from 12 to 15 in the stem, and from 7 to 12 in the rhizome. The seed coat is composed of sclereids, small bundles of sclerenchyma tissues, which prevent the influx of sea water from the outside and help endure the environmental stress. In conclusion, alternative multi-layer structure in circular, convex type aggregated leaf base are interpreted to morphological adaption as doing tolerable elastic structure through movement of seawater. The generative shoots develop long slim stem and branches in circular or ovoidal shapes to minimize the adverse impacts of sea current, which can be interpreted as the plant's morphological adaptation to its environment.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.21 no.2
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• pp.89-109
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• 1999

Vascular spasm which has been reported to occur in 25% of clinical cases continues to be a problem in microvascular surgery; When prolonged and not corrected, it can lead to low flow, thrombosis, and replant or free flap failure. Ischemia, intimal damage, acidosis and hypovolemia have been implicated as contributors to the vascular spasm. Although much work has been done on the etiology and prevention of vasospasm, a spasmolytic agent capable of firmly protecting against or reversing vasospasm has not been found. Therefore vascular freezing was introduced as a new safe method that immediately and permanently relieves the vasospasm and can be applied to microsurgical transfers. Cryosurgery can be defined as the deliberate destruction of diseased tissue or relief the vascular spasm in microvascular surgery by freezing in a controlled manner. 96 Sprague Dawley rats each weighing within 250g were used and divided into 2 group, experimental 1 and 2 group. In the experimental 1 group, right epigastric vessels (artery and vein) were freezed with a cryoprobe using $N_2O$ gas for 1 min. In the experimental 2 group, after freezing for 1 min, thawing for 30 secs and repeat freezing for 30 secs. Left side was chosen as control group in both group. We sacrified the experimental animals by 1 day, 3 days, 1 week, 2 weeks, 4 weeks & 5 months and observed the sequential change that occur during regeneration of epigastric vessels using a histologic, histomorphometric, immunohistochemical and SEM study after the vascular freezing. The results were as follows1. In epigastric arteries, internal diameters had statistically significant enlargement in 1 day, 3 days of Exp-1 group and 1 day, 3 days, 1 week & 2 weeks of Exp-2 group. Wall thickness had statistically significant thinning in 2 weeks of Exp-2 group. 2. In epigastric veins, internal diameters had enlargement of statistical significance in 1 day of Exp-1 and Exp-2 group. 3. The positive PCNA reactions in smooth muscle appeared in 1 week and increased until 2 weeks, decreased in 4 weeks. There was no statistical significance between Exp-1 and Exp-2 group. 4. The positive ${\alpha}$-SMA reaction in smooth muscles showed weak responses until 1 week and slowly increased in 2 weeks and showed almost control level in 4 weeks. 5. The positive S-100 reactions in the perivascular nerve bundles showed markedly decrease in 1 day, 3 days and increased after 1 week and showed almost control level in 4 weeks. Exp-1 group had stronger response than Exp-2 group. 6. In SEM, we observed defoliation of endothelial cell and flattening of vessel wall. Exp-2 group is more destroyed and healing was slower than Exp-1 group. To sum up, relief of vasospasm (vasodilatation) by freezing with cryoprobe was originated from the damage of smooth muscle layer and perivascular nerve bundle and the enlargement of internal diameter in vessels was similar to expeimental groups, but Exp-2 group had slower healing course and therefore vessel freezing in microsurgery can be clinically used, but repeat freezing time needs to be studied further.