• 한국양식학회지
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• 제16권3호
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• pp.196-201
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• 2003

Sessile organisms such as the oyster Crassostrea gigas have been given much attention as a potential biomonitoring indicator to assess the impact of toxicants on aquatic organism. In this study, we exposed cells isolated from gill of oyster (Crassostrea gigas) to hydrogen peroxide in vitro. In addition oysters were in vivo exposed to pyrene and benzo(a)pyrene at various concentrations for 2 weeks. Comet assay was used to detect DNA single strand breaks and to investigate the application of this technique as a tool for aquatic biomonitoring. Hydrogen peroxide increased DNA single strand break with increasing concentration after 30 minutes exposure in vitro. Pyrene and benzo(a)pyrene caused DNA damage only at very high concentration (100 $\mu\textrm{g}$/L or 1000 $\mu\textrm{g}$/L) at two week exposure in vivo. DNA damage was relatively higher at hemocyte than at gill. It suggested that metabolized PAHs are transferred to hemolymph from digestive gland which have a relatively high enzyme activity, and attacked the DNA of hemocyte, while gill accumulated PAHs without degrading them to their metabolites due to low enzyme activity at gill. Both in vitro and in vivo exposure experiments showed that the comet assay is an effective tool on screening whether the organism are exposed to genotoxic contaminants.

• Molecules and Cells
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• 제19권3호
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• pp.334-341
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• 2005

Plants are sessile and rely on a wide variety of growth hormones to adjust growth and development in response to internal and external stimuli. We have identified a gene, designated NAN, encoding a basic helix-loop-helix (bHLH) transcription factor that regulates cell elongation and seed germination in plants. NAN has an HLH motif in its C-terminal region but does not have any other discernible homologies to bHLH proteins. A bipartite nuclear localization signal is located close to the HLH motif. An Arabidopsis mutant, nan-1D, in which NAN is activated by the insertion of the 35S enhancer, exhibits growth retardation with short hypocotyls and curled leaves. It is also characterized by reduced seed germination and apical hook formation, symptomatic of GA deficiency or disrupted GA signaling. The phenotypic effects of nan-1D were increased by treatment with paclobutrazol (PAC), an inhibitor of gibberellic acid (GA) biosynthesis. NAN is constitutively expressed throughout the life cycle. Our observations indicate that NAN has a housekeeping role in plant growth and development, particularly in seed germination and cell elongation, and that it may modulate GA signaling.

• 한국세라믹학회지
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• 제20권4호
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• pp.289-296
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• 1983

The Wetting of fusion cast $Al_2O_3$ brick and $Al_2O_3 -ZrO_2$ brick by liquid Ag was studied by the sessile drop technique in Ar atmosphere. In this experiment the specimens were photographed per 2$0^{\circ}C$with increasing temperature from 96$0^{\circ}C$ melting point of Ag. And the method of photographing was carried out by shadow technique. The cosine of the contact angle increased linearly with increasing temperature in both systems. And the relation between the cosine of the contact angle and the temperature was Cos$\theta$=1.132+$0.75{\times}10^{-3}T$ for $Al_2O_3$ brick and Cos$\theta$=-1.706+$1.125{\times}10^{-3}T$ for $Al_2O_3 -ZrO_2$ brick In both systems the contact angle decreased as the surface of substrate became smoother. The work of adhesion which was 503.5ergs/$cm^2$ for $Al_2O_3$brick and 393.6 ergs/cm2 for $Al_2O_3 -ZrO_2$ brick at 96$0^{\circ}C$ increased parabolically with increasing temperature in both system.

• 식물분류학회지
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• 제40권3호
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• pp.169-173
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• 2010

제주도 동부지역의 저지대 상록활엽수림 내 습지에서 우리나라 미기록 종인 흑삼릉과(Sparganiaceae)의 남흑삼릉(Sparganium fallax Graebn.)이 채집되었다. 이 종은 지금까지는 일본, 중국, 대만, 인도, 인도네시아(수마트라), 미얀마, 뉴기니 등 우리나라보다 남쪽에만 분포하는 것으로 알려져 왔다. 남흑삼릉은 잎 뒷면에 능이 있고, 4-7개의 웅성 두상화서, 상대적으로 넓게 떨어져 있으면서 대개 자루가 없으나 최하위는 자루가 있는 자성 두상화서를 갖는다는 점에서 나머지의 흑삼릉과 식물들과 구분이 된다. 염색체 수는 2n = 2x = 30으로 2배체이며 염색체 크기는 $0.69-2.19{\mu}m$로 매우 작았다.

• 한국미생물·생명공학회지
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• 제30권1호
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• pp.86-90
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• 2002

포항제철소에서 사용하는 살균제와 공장냉각수를 사용하여 실험실에서 생물막 형성과 금속부식에 대한 연구를 수행하였다. 부유성 미생물은 biocide (NaOCl, 0.2％ w/v)을 첨가하면 1.5 시간 내에 모두 사멸하였으나, 생물막에 있는 고착성 미생물은 일주일이 지나도 사멸이 되지 않았다. 생물막 형성은 공장냉각수를 고온고압으로 멸균하거나, biocide(NaOCl)를 첨가하였을 경우에는 주황색의 생물막이 형성되었으나, 공장냉각수를 그대로 사용하였을 경우에는 SRB 활성에 의한 흑색(FeS)의 생물막이 형성되었다. 흑색의 생물막이 형성된 곳에서의 금속부식 속도는 주황색의 생물막이 형성된 곳의 금속부식 속도보다 2.3배 더 빨리 진행되었다.

• 한국분무공학회지
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• 제26권1호
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• pp.1-8
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• 2021

Droplet evaporation has been known as a common phenomenon in daily life, and it has been widely used for many applications. In particular, the influence of the different heated substrates on evaporation flux and flow characteristics is essential in understanding heat and mass transfer of evaporating droplets. This study aims to simulate the droplet evaporation process by considering variation of thermal property depending on the substrates and the surface temperature. The commercial program of ANSYS Fluent (V.17.2) is used for simulating the conjugated heat transfer in the solid-liquid-vapor domains. Moreover, we adopt the diffusion-limited model to predict the evaporation flux on the different heated substrates. It is found that the evaporation rate significantly changes with the increase in substrate temperature. The evaporation rate substantially varies with different substrates because of variation of thermal property. Also, the droplet evaporates more rapidly as the surface temperature increases owing to an increase in saturation vapor pressure as well as the free convection effect caused by the density gradient.

• Membrane and Water Treatment
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• 제13권4호
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• pp.173-181
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• 2022

Polyvinylidene fluoride (PVDF) flat sheet hydrophobic membranes were prepared using 16 wt% PVDF in Dimethyl acetamide (DMAc) by phase inversion technique for desalination application using Membrane Distillation (MD). In this work, the effect of coagulation mediums such as ethanol and water as well their synergistic behavior on the fabricated PVDF membrane morphology was studied using SEM. Moreover, other characteristics required for the membrane distillation applications namely porosity, hydrophobicity and tensile strength were measured using the gravimetric method, sessile drop method and universal testing machine respectively. It was observed that the membrane morphology paradigm shifted from the finger-like structure to the sponge-like structure on increasing the ethanol concentration in coagulant. The porosity of the fabricated membrane was under the required MD range and found to be 57.3% at 16 weight % of PVDF in DMAc solvent under a pure ethanol coagulant bath. Moreover, the top surface contact angle ranges from 85° to 115° on increasing the bath concentration from CBC 0 to CBC 100 at 16 weight % of PVDF in DMAc solvent.

• 치과방사선
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• 제29권2호
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• pp.523-531
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• 1999

Purpose: To determine the clinical and radiological features of peripheral osteoma of the mandible (POM) in a Korean population and to compare with previous reports. Materials and Methods: Sixteen cases of POM found in 15 Korean patients who visited Seoul National University Dental Hospital between 1980 and 1998 were reviewed to determine their clinical and radiological features. Results: The 15 patients. five males and ten females. ranged in age from 22 to 69 years. with a mean age of 40.7 years. Six POMs were located on the buccal side of the mandibular body and five on the lingual aspect of the mandibular body and five on the lower border of the mandible. The duration of the lesion ranged between 1 and 10 years. The size of the lesions. in their great diameter. ranged from 6 to 26 mm. with a mean of 14.1 mm. Six POMs were pedunculated. nine sessile. and one bell-shaped. Eleven POMs were compact types and five were cancellous ones. Conclusion: The clinical and radiological features of these Korean series were broadly consistent with those of non-Korean populations reported previously. The principal difference was that all POMs under 35 year-old age were compact types.

• Imaging Science in Dentistry
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• 제30권2호
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• pp.123-126
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• 2000

Pyogenic granuloma is a overzealous proliferation of a vascular type connective tissue as a result of some minor trauma and is a well circumscribed elevated, pedunculated or sessile benign inflammatory lesion of skin and mucous membrane. The clinical features of pyogenic granuloma are indicative but not specific and nearly all cases of pyogenic granulomas are superficial in nature, and there is little if any mention in the literature of these lesions producing alveolar bone even jaw bone loss. This case is somewhat unique in that the lesion was an obvious histologic pyogenic granuloma; however, it appeared to invade the mandibular bone which resulted in the loss of the adjacent teeth. A 12-year-old boy came to Seoul National University Dental Hospital with chief complaints of left facial swelling. The features obtained were as follows; Plain radiograms showed a large well-circumscribed radiolucent lesion on left mandibular ramus area, which made severe expansion of lingual cortex and displacement of lower left 3rd molar tooth germ. Computed tomograms showed large soft tissue mass involving left masticator space with destruction of left mandibular ramus. Histologically, sections revealed loose edematous stroma with intense infiltration of inflammatory cells and proliferation of vascular channels. Also, there were focal areas of extensive capillary proliferation, bone destruction and peripheral new bone formation.

• 한국버섯학회지
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• 제14권3호
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• pp.75-80
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• 2016

국내에서 분리한 신규 P linteus KACC93057P의 자실체의 형태적 특성을 육안적 으로 관찰한 결과 대가없이 기주부착형으로 자실체표면은 단단한 목질형태 (hardy woody) 로 동심원으로 윤층대 (zonate)와 홈을 형성하고 담갈색을 띠고 있었다. 자실체 뒷면 테두리는 진황색, 내부는 담황갈색을 띠며 현미경 미세구조를 관찰한 결과 관공은 원형또는 각진형이며, 관공구는 5-7 per mm크기로 나타났다. hyphal system은 2분지형이며 포자는 $4.5-6{\times}4-5{\mu}m$크기로 난형또는 유구형 담갈색을 띠어 P linteus와 유사한 특성을 보였다. YGMA배지상에서 KACC93057P는 $25-30^{\circ}C$가 최적온도로 균사체 성장률이 장수상황과 고려상황에 비하여 10-25% 높았으며 균사밀도가 다른 균주보다 현저히 높게 나타났다. ITS-rDNA염기서열비교결과 96% 이상의 상동성으로 I. lonicericola, I. linteus, I. baumii와 근연관계를 형성 하였다.