• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.25 no.2
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• pp.87-104
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• 1989

Recently, with the tendency of more lightening, high-strength and high-speed in the marine industries such as marine structures, ships and chemical plants, the use of the aluminium Alloy is rapidly enlarge and there occurs much interest in the study of corrosion fatigue crack characteristics. In this paper, the initiation of surface crack and the propagation characteristics on the base metal and weld zone of 5086-H116 Aluminium Alloy Plate which is one of the Al-Mg serious alloy(A5000serious) used most when building the special vessels, were investigated by the plane bending corrosion fatigue under the environments of marine, air and applying cathodic protection. The effects of various specific resistances on the initiation, propagation behavior of corrosion fatigue crack and corrosion fatigue life in the base metal and heat affected zone were examined and its corrosion sensitivity was quantitatively obtained. The effects of corrosion on the crack depth in relation to the uniform surface crack length were also investigated. Also, the structural, mechanical and electro-chemical characteristics of the metal at the weld zone were inspected to verify the reasons of crack propagation behavior in the corrosion fatigue fracture. In addition, the effect of cathodic protection in the fracture surface of weld zone was examined fractographically by Scanning Electron Microscope(S.E.M.). The main results obtained are as follows; (1) The initial corrosion fatigue crack sensitibity under specific resistance of 25Ω.cm% show 2.22 in the base metal and 19.6 in the HEZ, and the sensitivity decreases as specific resistance increases (2) By removing reinforcement of weldment, the initiation and propagation of corrosion crack in the HAZ are delayed, and corrosion fatigue life increases. (3) As specific resistance decreases, the sensitivity difference of corrosion fatigue life in the base metal and HAZ is more susceptible than that of intial corrosion fatigue crack. (4) Experimental constant, m(Paris' rule) in the marine environment is in the range of about 3.69 to 4.26, and as specific resistance increases, thje magnitude of experimental constant, also increases and the effect by corrosion decreases. (5) Comparing surface crack length with crack depth, the crack depth toward the thickness of specimen in air is more deeply propagated than that in corrosion environment. (6) The propagation particulars of corrosion fatigue crack for HAZ under initial stress intensity factor range of $\Delta$k sub(li) =27.2kgf.mm super(-3/2) and stress ratio of R=0 shows the retardative phenomenon of crack propagation by the plastic deformation at crack tip. (7) Number of stress cycles to corrosion fatigue crack initiation of the base metal and the welding heat affected zone are delayed by the cathodic protection under the natural sea water. The cathodic protection effect for corrosion fatigue crack initiation is eminent when the protection potential is -1100 mV(SCE). (8) When the protection potential E=-1100 mV(SCE), the corrosion fatigue crack propagation of welding heat affected zone is more rapid than that of the case without protection, because of the microfissure caused by welding heat cycle.

• Journal of the Mineralogical Society of Korea
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• v.20 no.3
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• pp.181-191
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• 2007

The gemological charateristics of Gwangdong tektites and Baikdusan obsidians were investigated, using microscopy, density and refractive index measurements, X-ray fluorescence spectrometry, Inductively Coupled Plasma Mass spectrometry, X-ray powder diffraction, and electron microprobe analysis. The Gwangdong tektites and Baikdusan obsidians are both black in colour and slightly trans-lucent with various shades of brown when cut into a few mm thick. Both the materials yield conchoidal fracture on broken surface. The tektites occur as tear-drop shapes, ranging from 4 to 10 cm long, and in spheres, from 3 to 5 cm in diameter. On the surface numerous shallow pits up to 3 mm in diameter are present. Mohs' hardness and specific gravity are 5 to 5.5 and 2.66, respectively. The tektites are singly refractive, with an refractive index of 1.51. Numerous spherical air bubbles are randomly scattered throughout the tektites, and silica-rich glass inclusions are occasionally seen. X-ray powder diffraction analysis verifies that they are non-crystalline. The Baikdusan obsidians show very similar properties to those of the Gwangdong tektites, especially in hardness, amorphous nature and fracture. Nevertheless, the Baikdusan obsidian can readily be distinguished from the Gwangdong tektites by refractive index ($1.49{\sim}1.50$), specific gravity (2.67 to 2.68), and inclusions (absence of bubbles and presence of sanidine and magnetite crystals).

• Economic and Environmental Geology
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• v.35 no.4
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• pp.355-368
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• 2002

The multi-storied Daewonsa stone pagoda (Treasure No. 1112) in the Sancheong, Korea was studied on the basis of deterioration and geological safety diagnosis. The stone pagoda is composed mainly of granitic gneiss, partly fine-grained granitic gneiss, leucocratic gneiss, biotite granite and ceramics. Each rock of the pagoda is highly exfoliated and fractured along the edges. Some fractures in the main body and roof stones are treated by cement mortar. This pagoda is strongly covered with yellowish to reddish brown tarnish due to the amorphous precipitates of iron hydroxides. Dark grey crust by manganese hydroxides occur Partly, and some Part coated with white grey gypsum and calcite aggregates from the reaction of cement mortar and rain. As the main body, roof and upper part of the pagoda, the rocks are developed into the radial and linear cracks. Surface of this pagoda shows partly yellowish brown, blue and green patchs because of contamination by algae, lichen, moss and bracken. Besides, wall-rocks of the Daewonsa temple and rock aggregates in the Daewonsa valley are changed reddish brown color with the same as those of the pagoda color. It suggests that the rocks around the Daewonsa temple are highly in iron and manganese concentrations compared with the normal granitic gneiss which color change is natural phenomena owing to the oxidation reaction by rain or surface water with rocks. Therefore, for the attenuation of secondary contamination, whitening and reddishness, the possible conservation treatments are needed. Consisting rocks of the pagoda would be epoxy to reinforce the fracture systems for the structural stability on the basements.

• Economic and Environmental Geology
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• v.43 no.4
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• pp.371-379
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• 2010

Fresh water injection test in a fractured bedrock aquifer was applied as an efficient approach to lower saline concentrations in the saltwater-freshwater transition zone formed by seawater intrusion in a coastal area. The methodology and effectiveness of fresh water injection for hydraulically controlling seawater intrusion is overwhelmingly site dependent, and there is an urgent need to characterize the permeable fractures or unconsolidated porous formations which can allow for seawater flow and transport. Considering aquifer characteristics, injection and monitoring boreholes were optimally designed and completed to inject fresh water through sand layer and fractured bedrock, respectively. We devised and used the injection system using double packer for easy field operation and maintenance. Overall fracture distribution was systematically identified from borehole image logs, and the section of fresh water injection was decided from injection test and monitoring. With fresh water injection, the fluid electrical conductivity of the monitoring well started to be lowered by the inflow of fresh water at the specific depth. And this inflow leaded to the replacement of the fluid in the upper parts of the borehole with fresh water. Furthermore, the injection effect lasted more than several months, which means that fresh water injection may contribute to the mitigation of seawater intrusion in a coastal area.

• Journal of Periodontal and Implant Science
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• v.29 no.2
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• pp.297-313
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• 1999

The ultimate goal of periodontal treatment is the regeneration of periodontal tissues which have been lost due to periodontal disease. Recently, many natural medicines have been studied for their potential of anti-bacterial, anti-inflammatory and regenerative effects in periodontal tissues. Safflower seeds have been traditionally used as a drug for treatment of fracture and blood stasis in oriental medicine. The objective of the present study is to examine the biologic effects of safflower seeds extract on bone formation and regeneration of rat calvarial defects. The calvarial defects were made with 8mm trephine bur and extract of safflower seeds were placed directly at these defects. 24 rats were divided into control and experimental groups, and each group was sacrificed at 1 week, 4 weeks and 8 weeks. To study a histopathology related to bone regeneration, Goldner's Masson Trichrome stain and histomorphologic measuring was done at each weeks. In the early phase of bone healing, less inflammatory infiltration and capillary proliferation was found in experimental group compared to control. Dense bony tissues and matured bone structures in defect areas were found in experimental groups. And area of new bone formation was significantly increased at 8 weeks in experimental group. These results indicate that direct local application of safflower seeds extract reduces the early inflammatory response and promotes the regeneration of new bone in calvarial defects of rats.

• Journal of Periodontal and Implant Science
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• v.30 no.3
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• pp.553-569
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• 2000

Many natural medicines have been studied for their capacity and effects of antibacterial, anti-inflammatory and regenerative potential in periodontal tissues. Safflower seed has been traditionally used as a drug for treatment of bone fracture in oriental medicine. The purpose of the present study was to compare the effects of safflower seed extract and bone substitute on bone formation and regeneration in artificial defects in mongrel dogs. The bony defects were made with round bur at mandible and tibia. Extracts of safflower seed and bovine bone were placed directly at each defect for experimental group, and the defect of control group was sutured without any other treatment. Experimental animals were sacrificed at 8 weeks. And then histopathologic reading and histomorphometric study was done. There was not significant differences between control and experimental groups in osteoclastic activity and infiltration of inflammatory cells. However, new capillary proliferation, fibrosis and new bone formation were prominent in safflower seed extract group. The mandibular defects of safflower seed extract group were healed with dense connective and bony tissues, and endochondral bone formation was observed in tibial defect of safflower seed extract group only. New bone area of safflower seed extract group was more significantly increased than that of control and that of bone substitute group. These results indicate that direct local application of safflower seed extracts on bony defects seems to reduces the early inflammatory response and to promotes the bone regeneration.

• The Journal of Korean Academy of Prosthodontics
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• v.56 no.4
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• pp.384-390
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• 2018

Hybrid telescopic double crown have ever been good treatment option for patient with periodontally unfavorable few remaining teeth for successful prognosis. Tooth and implant combined telescopic double crown can be used for improving retention and support for denture with strategically placed implants on edentulous ridge. In this case, an 55-year-old female patient had chronic periodontitis with few remaining teeth on maxilla and fixed partial prosthodontics on mandible. Treatment of hybrid telescopic double crown with friction pin lasted 9.5 years only with natural teeth. After 9.5 years, additional implants was installed due to fracture of cast-posted abutment teeth. After implantation, tooth and implant combined double crown had fabricated. Through re-treatment, no complications of new denture has been found during 2 years follow up. This case presents fair prognosis of tooth and implant combined double crown denture in periodontally unfavorable condition.

• The Journal of Engineering Geology
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• v.7 no.3
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• pp.229-245
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• 1997

There are Common aspects between the underground oil storage cavern and the radioactive waste disposal facility. Both facilities use appropriately the intrinsic natural berrier characteristics of the rock mass and additionally the engineered barrier system for the long term safety. The geological structures and their hydrogeological characteristics in a faactured rock mass act a major role in the safety and performance of the underground oil storage facility through the design, construction and the operation stages. Because the fracture system distributed in a fractured rock block is complicated owing to their own geometrical and hydrogeological attributes, the hydrogeological perforrmrnce of the facility would depend mainly upon the understandings of their characteristics. This study reviews the uncertainties and key issues which have to be considered to analyse the groundwater flow system in a fractured rock mass and proposes the techniques applicable to characterize the hydrogeological parameter.

• Applied Microscopy
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• v.20 no.2
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• pp.81-101
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• 1990

Toad bladder의 상피수송(上皮輸送)을 분석(分析)하기 위하여 동결치환(凍結置換) 및 동결절단법(凍結切斷法)을 적용(適用)하여 전자현미경(電子顯微鏡) 관찰(觀察)을 실시하였다. 방광(膀胱)의 점막층(粘膜層)은 과립성세포(顆粒性細胞), 미토콘드리아가 풍부한 세포, 점막분필세포(粘膜分泌細胞) 및 기저세포(基底細胞)등 4가지 세포로 구성되어 있었다. 과립성세포(顆粒性細胞)는 점막표면적의 대부분을 점유하며 $Na^+$ 수송(輸送)에 주요한 역할을 하고, 정단부(頂端部)의 세포질에는 다수의 과립이 분포하며 정단세포막(頂端細胞膜)은 microvilli type I로 배열되어 있고, 표면에 glycoprotein을 함유하는 세포외막(細胞外膜)이 관찰되었다. 대조적으로 미토콘드리아가 풍부한 세포는 세포질 전역에 걸쳐 다수의 미토콘드리아가 분포해 있으며 주요 기능은 $H^{+},\;K^{+}$ 및 $HCO_{3}^{-}$ 분필수송(分泌輸送)에 관여할 것으로 생각되며 이들 수송상피(輸送上皮)는 정단부가 견고연접(堅固連接)으로 둘러 싸이고 기저세포막(基底細胞膜)은 인접세포와 서로 분리되므로 상피세포의 극성이 유지되며 정단부(頂端部) 세포막과 기저세포막의 수송특성(輸送特性)은 각기 다르다고 생각된다. 따라서 두꺼비 방광(膀胱)에서 상피수송(上皮輸送)은 세포 통과수송 및 세포간 분류수송 경로를 나타내고 있다. 한편 세포막 투과성(透過性)의 조절과 관련하여 동결절단(凍結切斷) 전자현미경 관찰에 의하면 forskolin에 촉진된 정단부(頂端部) 세포막 투과성의 변화는 세포막내(細胞膜內) 입자(粒子)의 분포와 밀접한 관계를 가지는 것으로 보인다. 특히 과립성세포(顆粒性細胞)에서 집단으로 관찰되는 세포막내(細胞膜內) 입자(粒子)는 forskolin에 유도된 정단세포막(頂端細胞膜) 투과성의 변화를 나타내주는 것으로 사료되나 이의 기능적 의미에 대하여는 연구가 더욱 필요하다고 본다.

• Journal of Veterinary Clinics
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• v.28 no.4
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• pp.375-386
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• 2011

Polygoni Multiflori Radix (PMR), a dried root tuber of Polygonum multiflorum Thunberg with bioactivities in bone metabolism is one of the most famous tonic traditional medicines. To observe in vivo anti-osteoporotic efficacy of PMR extracts, we orally administered once a day for 28 days (Qd ${\times}$ 28) to bilateral ovariectomized (OVX)-induced osteoporosis ddY mice after 1 week of recovery periods at 125, 250 and 500 mg/kg (of body weight). A positive control drug, Alendronate (FOSA) 10 mg/kg-dosing group was added. As results of OVX-induced osteoporotic process, estrogen-deficient osteoporotic changes were also dramatically decreased in all PMR extracts-dosing groups. Especially middle dosage of PMR extracts, 250 mg/kg constantly and significantly (p < 0.01 or p < 0.05) inhibited the loss of bone strength and bone quality. Based on the results, it was concluded that PMR extracts (125, 250 or 500 mg/kg; orally dosing) has relatively good favorable effect to prevention and/or treatment of OVX-induced osteoporosis. Therefore, although the efficacy was slighter than that of Alendronate on the inhibition of bone loss, it is expected that PMR extracts will be promising as a new anti-osteoporotic agents for prevent the fracture induced in osteoporotic patients because natural herbal medicine origin PMR extracts will be dose not show serious side effects especially the problem in upper alimentary irritation by bisphosphonate and hypercalcaemia of parathyroid hormone analogs.