• Journal of the Korean Society of Food Science and Nutrition
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• v.39 no.4
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• pp.494-499
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• 2010

In this study, Sargassum coreanum was enzymatically hydrolyzed to prepare water-soluble extracts by using five carbohydrates (Viscozyme, Celluclast, AMG, Termamyl and Ultraflo) and five proteases (Protamex, Kojizyme, Neutrase, Flavozyme and Alcalase) and their potential antioxidant activity were evaluated. The Celluclast and Neutrase extracts of Sargassum coreanum exhibited better DPPH radical scavenging activities (92.42% and 92.78%, respectively) and hydrogen peroxide ($H_2O_2$) scavenging activities (58.28% and 57.97%, respectively) compared to those of other enzymatic extracts. These results suggest that Sargassum coreanum would be a good raw materials for antioxidant and enzymatic hydrolysis would be a good strategy to prepare antioxidant extracts from seaweeds.

• Journal of the Earthquake Engineering Society of Korea
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• v.12 no.4
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• pp.19-33
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• 2008

Dynamic response measurements from natural excitation were carried out for 25- and 42-story buildings to evaluate their inherent properties, such as natural frequencies, mode shapes and damping ratios. Both are reinforced concrete buildings adopting a core wall, or with shear walls as the major lateral force resisting system, but frames are added in the plan or elevation. In particular, shear walls in a 25-story building are converted to frames from the 4th floor level downwards while maintaining a core wall throughout, resulting in a fairly complex structure. Due to this, along with similar stiffness characteristics in the principal directions, significantly coupled and closely spaced modes of motion are expected in this building, making identification rather difficult. By using various state-of-the-art system identification methods, the modal parameters are extracted, and the results are then compared. Three frequency-domain and four time-domain based operational modal identification methods are considered. Overall, all natural frequencies and damping ratios estimated from the different identification methods showed a greater consistency for both buildings, while mode shapes exhibited some degree of discrepancy, varying from method to method. On the other hand, in comparison with analysis results obtained using the initial finite element(FE) models, test results exhibited a significant difference of about doubled frequencies, at least for the three lower modes in both buildings. To improve the correlation between test and analysis, a few manual schemes of FE model updating based on plausible reasons have been applied, and acceptable results are obtained. The advantages and disadvantages of each identification method used are addressed, and some difficulties that might arise from the updating of FE models, including automatic procedures, for such large structures are carefully discussed.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.34 no.9
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• pp.875-883
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• 2010

The thermal performance of LNG fuel tanks of vehicles is determined by the time for non-venting storage of fuel and the amount of fuel supplied to the engine. In this study, we selected a double-walled vacuum-insulated fuel tank with a volume of 450 liter, and the properties of the fuel contained in it were assumed to be the same as those of the methane($CH_4$). For the increasing the non-venting fuel storage time, we propose the use of shielded penetration pipes in the tank. We compared the storage times of the tank used in our study with those of the conventional fuel tank. Further, the additional heat input required to maintain the fuel pressure necessary for an appropriate fuel supply rate was predicted. For these parameters, we derived a thermodynamic relationship that can be used to estimate the rate of increase in pressure for a known heat input, and we obtained equations for estimating the rate of heat leaked by using the established heat transfer model. From the results of numerical computation, we found the non-venting storage time of the tank with shielded pipes to be 25-30% higher than that of the tank with unshielded pipes. Further, we determined the appropriate operation conditions by taking into consideration the transfer rate of additional heat provided to the fuel tank.

• Korean Journal of Microbiology
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• v.35 no.2
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• pp.139-145
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• 1999

Aromatic hydrocarbons which are not easily degraded by microorganisms can be accumulated in the conlaminated environment for a long lime, producing toxic effects on wild lives and humans. However, the sublethal concentrations of the chemicals induce the synthesis of stress-shock proteins in the cells and increase the adaptability of the organisms to the environmental stresses. In this study, therefore, the cells of Psezido~nonus sp. DJ- 12 treated with catechol at various concentrations were inveshgated for their survival, biodegtadability of catechol, production of stress-shock proteins, and cytological changes. The organisms were capable of degrading catechol at the range of 0.5 to 1.0 mM concentration wilhin 6 hours incubation, but they were killed by $10^2$-10$^3$ celllinl at 3 mM or higel- concentration without any catechol degradation. These cells treated with catechol begm lo produce DnaK and GroEL at 1 mM and 0.5 mM. respectively. Pseudumonas sp. DJ-12 treated with 10 mM catechol for I hour exhihiled some punctuated pores on the cell wall and contortion of the rod shape. The cells treated with he sublethal concentration of catechol showed the increased tolerance for suvival when exposed to the lethal concentration, and such tolerant effects were functioned crossly among benzoate, 4-chlorobenzoate, 'and catechol.

• Korean Journal of Food Science and Technology
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• v.44 no.3
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• pp.343-349
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• 2012

Polysaccharides isolated from Korean black raspberry wine were examined for their chemical properties and immuno-modulating activities. The molecular mass of RB-1b-I, the main polysaccharide in black raspberry wine, was estimated as 180 kDa and it contained a significant proportion of mannose (76.8%) and 4 different minor component sugars such as galactose (15.8%), arabinose (3.8%), glucose (2.6%) and rhamnose (1.2%). This indicated that RB-1b-I was mainly present as a mannan, which had originated from the cell walls of fermenting yeasts. On the other hand, RB-1b-I induced high levels of macrophage activation as well as mitogenicity regarding murine splenocytes in vitro. The intravenous administration of RB-1b-I significantly augmented NK cytotoxicity against YAC-1 tumor cells. RB-1b-I also showed potent anti-complementary activity in a dose-dependent manner via both alternative and classical pathways. Results indicated that Korean black raspberry wine contains peculiar polysaccharides which provide beneficial immuno-stimulating activities for human health.

• Journal of the korean academy of Pediatric Dentistry
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• v.38 no.1
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• pp.44-50
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• 2011

An immature tooth with infected pulp has numerous potential complications. Conventional apexification with calcium hydroxide has several disadvantages, including susceptibility to tooth fracture. This method does not promote continual root development. Pulp revascularization of a necrotic, immature permanent tooth will allow further development of the root and dentinal structure. Disinfection of the root canal system is a prerequisite for pulp revascularization and tissue regeneration. A combination of antibiotic drugs (ciprofloxacin, metronidazole, and minocycline) is effective for disinfection of necrotic pulp, and has been used successfully in regenerative endodontic treatment. These case reports involve the treatment of 3 immature permanent teeth with necrotic pulp using a 3-Mix paste and mineral trioxide aggregate. All cases showed the notable apical maturation with closure of the apex and increased thickness of dentinal walls. This approach suggests a paradigm shift in treating endodontically involved immature permanent teeth from the traditional apexification with calcium hydroxide to the conservative approach by providing a favorable environment for tissue regeneration.

• Journal of Dental Rehabilitation and Applied Science
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• v.28 no.2
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• pp.201-212
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• 2012

There are some similar aspects at histological and morphological characteristics between the peri-implant tissue and periodontal tissue and the direct attachment between the titanium and soft tissue around the implant called as "Functional ankylosis" can prevent the apical infiltration of inflammatory and bone resorption around implant. But, the repeated connection and disconnection of the abutment can destroy the mucosal barrier of soft tissue around the implant and can cause the marginal bone resorption. The amount of marginal bone resorption may reduced if the prosthetic abutment is placed at that time of surgery. Connection of the prosthetic abutment at surgery was limited because the low accuracy of conventional method, but by using of Cone Beam Computed Tomography(CBCT) and guide surgery, the 3-dimensional accuracy of implant placement became much higher than before and it became possible. This is a clinical case of immediate connection of prosthetic abutment and provisional restoration by using of precise CBCT diagnosis and pre-fabricated zirconia customized abutment at surgery and the alternative method is described in this article because of the clinically contentable results.

• Journal of Periodontal and Implant Science
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• v.36 no.2
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• pp.409-425
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• 2006

치주질환의 병원균은 세포벽의 항원에 의하여 조직내 존재하는 mononuclear phagocytes가 활성화되어 cytokine들이 생성됨 으로써 치주 결체조직의 파괴를 진행시킨다. 이런 관련된 cytokine들은 순차적으로 상주하는 치은세포 및 대식세포가 Matrix metalloproteinase 합성을 하도록 유도하여 조직파괴를 시작한다. 이들 Matrix metalloproteinase중 MMP-2, MMP-9 (Gelatinase A,B)는 type IV collagen 및 변성된 interstitial collagen을 파괴하며 치주환자의 치은 열구액, 치은조직, 타액 네에서 높게 보고 되어왔다. 당뇨병은 치주질환의 위험요소중 하나로 달뇨 환자에서는 치주질환의 유병율이 일반인에 비해 높고 치주질환의 중증도도 더 심하여 진행도 빠르다고 알려져 있다. 그 병리 기전 중 하나로는 당뇨 환자에서는 치은 열구액 내 중성구 유래의 Matrix metalloproteinase의 활성 증가 및$TNF-{\alpha}$ 의 활성 증가가 추정되고 있다. 본 실험에서는 제2형 당뇨병 환자와 비당뇨 환자들에서 만성 치주염 부위의 치은 및 건강한 치은에서 염증매개체 중 하나인 MMP-2, MMP-9 및 $TNF-{\alpha}$ 의 발현에 대해 상호 비교 분석함으로서 염증, 혈당이 미치는 영향을 밝히고 제 2형 당뇨병 환자에서 심한 치주조직 파괴의 기전을 연구하고자 하였다. 경북대학교병원 치주과 내원환자 중 제2형 당뇨병 환자와 비당뇨 환자들 및 치주질환이 없는 건강인 대조군을 대상으로 여러 가지 환자요소, 임상 치주상태를 기록하고, 전신적으로 건강한 환자의 건강한 부위(n=8,Group 1), 전신적으로 건강한 환자으 만성 치주염 부위(n=8, Group 2), 제2형 당뇨병 환자의 만성 치주염 부위 (n=8,Group 3)에서 각각 변연치은을 채득하고 액화질소에 급속 동결하였다. Western blotting을 이용하여 각 조직 내 MMP-2, MMP-9 및 $TNF-{\alpha}$ 의 발현을 관찰, densitometer를 이용하여 상대적 발현을 정량, 각 조직의${\beta}-actin$을 이용하여 표준화하여 실험군과 대조군들의 평균치를 비교하였다. 비당뇨 환자들의 만성 치주염 부위 및 제2형 당뇨병 환자의 만성 치주염 부위에서 모두 건강 대조군에 비해 MMP-2와 MMP-9 의 발현이 증가되었다. 또한 MMP-2와 MMP-9는 2형 당뇨 환자의 만성 치주염 부위가 비당뇨 환자의 만성 치주염 부위보다 증가된 발현양상을 보였으며, $TNF-{\alpha}$ 발현 비교시 각 군간 유의성 있는 변화는 없었으나 2형 당뇨환자군에서 MMP-2 및 MMP-9의 증가와 함께 다소 증가 양상을 보였다. 결론적으로 본 실험에서 MMP-2 및 MMP-9의 증가가 만성 치주염 및 2형 당뇨 환자에서의 만성치주염에서 비당뇨환자 보다 MMP-2, MMP-9의 증가양상을 보여 주었으며 $TNF-{\alpha}$ 가 2형 당뇨환자의 만성치주염 진행과정에 기여인자로써 역할을 하는 것으로 생각된다.

• Journal of the Society of Naval Architects of Korea
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• v.34 no.1
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• pp.1-10
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• 1997

Viscous flow around actual ship is calculated by an use of RANS equations. The propriety of this computing method, usefulness to hull form design and the scale effect which is the effect of viscous flow depending on the scale of ship model are investigated. Reynolds stress is modelled by using k-${\varepsilon}$ turbulence model and the law of wall is applied near the body. Body fitted coordinates are introduced for the treatment of the arbitrary 3-dimensional shape of the ship hull form. The transformed equations in the computational domain are numerically solved by an employment of FVM. In the calculation of pressure, SIMPLE method is adopted and the solution of the discretized equation is obtained by the line-by-line method with the use of TDMA The calculations of two ships, 4410 TEU container carrier and 50,000 DWT class bulk carrier, are performed at model and actual ship scale. The results are compared and discussed with the model test results which are viscous resistance, nominal wake distribution at propeller plane and limiting streamline on the hull surface. They describe the effect of stem form and the scale effect very well. In particular, the calculated nominal wake distribution and limiting streamline are agreed qualitatively with the experiments and the viscous resistance values are estimated within ${\pm}5%$ difference from the resistance tests.

• Korean Journal of Plant Tissue Culture
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• v.21 no.5
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• pp.309-314
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• 1994

To develop simple and efficient transformation methods of monocotyledonous plane, electroporation-mediated delivery of DNA into intact embryogenic cell clumps was investigated in zoysiagrass and rice. Calli of zoysiagrass, induced from 3-week-old immature embryos, were suspension-cultured in MS basic medium supplemented with 1.0 mg/t 2.4-D and used for elechuporation. Calli, derived from immature inflorescences of 20 mm lenth of rice, were also suspension-cultured on N6 basic medium supplemented with 1.0 mg/L 2.4-D. Suspension-cultured embryogenic cell clumps were electroporated in liqid MS medium added with a Plasmid DNA (30 $\mu\textrm{m}$/ml), pGA1074, encoding ${\beta}$-glucuronidiase (GUS). DNA delivery into the cells through cell walls and cell membrane was confirmed by the transient expression of the GUS gene. Cell clumps of zoysiagrass and rice, electroporated with 400 volt at 800 pF capacitance, expressed GUS gene activity at a mean frequency of 25 units (one unit = one clony of blue cells) per 200 ${\mu}\ell$ of packed cell volume. Untreated cells and healed non-embryogenic cells did not exhibit GUS activity These results indicate that electroporation-mediated transformation can use intact embryogenic cells (thus avoiding the use protoplasts) in zoysiagrass and rice.