• 한국양식학회지
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• 제16권4호
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• pp.223-228
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• 2003

전복 치패를 부착기질로부터 분리시키는 박리는 전복양식에 있어서 치패의 선별과 밀도 조절을 위해 필수적인 작업이다. 현재 물리적인 방법과 마취제를 이용한 방법이 개발되어 있으나 치패의 손상이 없는 마취제에 의한 박리가 보다 효과적인 것으로 판단되고 있다. 따라서 본 연구는 요소비료($Co(NH_2)_2$)를 마취제로 이용하여 요소비료의 농도와 수온 등 물리적 요인이 까막전복 Haliotis discus의 박리율과 회복률에 미치는 영향을 조사함으로써 경제적이며 효과적인 박리 기술을 개발하고자 하였다. 실험 결과 9∼15%의 요소비료를 해수에 용해시키고 이를 자연 해수와 동일한 수온으로 상승시킨 후 박리를 실시하였더니 3분 이내에 97% 이상이 박리되었으며 치패의 회복률도 역시 높았다. 또한 요소비료 농도와 수온은 높을수록 박리율도 높았으나 치패의 회복률은 낮았다. 결론적으로 본 연구를 통하여 농업용 요소비료를 전복의 박리에 사용할 수 있음을 확인하였으며, 다른 종류의 전복에서도 본 기술의 적용이 가능할 것으로 생각되며, 본 기술은 현재 사용되고 있는 모든 전복 박리방법이나 전복 마취제로 쓰이는 화학약품을 대체할 수 있는 방법으로 판단된다.

• 한국재료학회지
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• 제23권12호
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• pp.708-713
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• 2013

Graphene oxide has been synthesized by microwave-assisted exfoliation of graphite oxide prepared by modified Hummers method. Graphite was oxidized in a solution of $H_2O_2$ and $KMnO_4$ at $65{\sim}80^{\circ}C$, followed by 10 % $H_2O_2$ solution treatment at $80{\sim}90^{\circ}C$. The graphite oxide was exfoliated under microwave irradiation of 1 kW and was reduced to graphene effectively by hydrazine hydrate ($H_4N_2{\cdot}H_2O$) treatment. The exfoliation of graphene oxide was significantly affected by the microwave irradiation on (heating)/off (cooling) period. An on/off period of 10 s/20 s resulted in much more effective exfoliation than that of 5 s/10 s with the same total treatment time of 10 min. This can be explained by the higher exfoliation temperature of 10 s/20 s. Repetition of the graphite oxidation and exfoliation processes also enhanced the exfoliation of graphene oxide. The thickness of the final graphene products was estimated to be several layers. The D band peaks of the Raman spectra of the final graphene products were quite low, suggesting a high crystal quality.

• 대한소아치과학회지
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• 제4권1호
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• pp.19-23
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• 1977

178 naturally exfoliated maxillary deciduous central incisors, 149 deciduous lateral incisors of children at exfoliation stage were studied on the degree and the tendency of the root resorption, and the age of exfoliation of the deciduous central and lateral incisors. The results were as follows; 1. The root of maxillary deciduous central and lateral incisors tended to be resorbed disto-lingually. 2. The age of exfoliation of maxillary deciduous central incisor was 7.27 year in male, 7.01 year in female, and the age of exfoliation of maxillary deciduous lateral incisor was 8.22 year in male, 7.77 year in female. 3. The exfoliation age of maxillary deciduous central and lateral incisors was earlier in female than in male.

• 동력기계공학회지
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• 제18권6호
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• pp.7-12
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• 2014

The effect of various synthesis conditions in the fabrication of graphene using the exfoliation methods has been investigated. Graphite oxide and graphene fabricated by various synthesis conditions were identified by SEM and XRD. Graphite oxide was made from graphite by the chemical oxidation, and graphene was manufactured from graphite oxide by thermal exfoliation method. As a result, it is confirmed that graphite oxide was well formed from graphite, and the graphene could be obtained from graphite oxide. And it was found that the interlayer spacing between the graphene layers depended on the reaction time and particle size, regardless of the reaction temperature from $5^{\circ}C$ to $25^{\circ}C$.

• 공업화학
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• 제30권2호
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• pp.133-140
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• 2019

Two-dimensional (2D) ultrathin molybdenum dichalcogenides $MoS_2$ has gained a great deal of attention in energy conversion and storage applications because of its unique morphology and property. The 2D $MoS_2$ nanosheets provide a high specific surface area, 2D charge channel, sub-nanometer thickness, and high conductivity, which lead to high electrochemical performances for energy storage devices. In this paper, an overview of properties and synthetic methods of $MoS_2$ nanosheets for applications of supercapacitors and rechargeable batteries is introduced. Different phases triangle prismatic 2H and metallic octahedral 1T structured $MoS_2$ were characterized using various analytical techniques. Preparation methods were focused on top-down and bottom-up approaches, including mechanical exfoliation, chemical intercalation and exfoliation, liquid phase exfoliation by the direct sonication, electrochemical intercalation exfoliation, microwave-assisted exfoliation, mechanical ball-milling, and hydrothermal synthesis. In addition, recent applications of supercapacitors and rechargeable batteries using $MoS_2$ electrode materials are discussed.

• 한국어병학회지
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• 제25권2호
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• pp.123-126
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• 2012

전복 양식현장에서 수산용 항생제인 옥시테트라사이클린(Oxytetracycline, OTC)에 노출된 전복은 부착판에서 박리되는 현상이 관찰되었다. 본 연구에서는 수산용 OTC의 전복박리 성분을 규명하고자 하였다. 전복은 14,000 ppm의 OTC 농도(수산용 OTC 성분: OTC-HCl; 50%, 포도당; 49%, 청색색소; 1% 이하)에서 100% 박리되었으나 8,000 ppm 이하의 농도에서는 박리되지 않았다. 95%의 박리율은 7,000 ppm의 OTC-HCl(pH 2.8)에서 나타났으나, 7,000 ppm의 OTC-HCl (pH 5.0), 7,000 ppm의 포도당 및 140 ppm의 청색색소에서는 박리 효과가 나타나지 않았다. 더욱이 100%의 박리율은 HCl (pH 2.8)에서 나타나, 전복은 상업용 OTC에 함유되어 있는 HCl에 의해 부착판에서 박리되는 것으로 확인되었다. 전복은 HCl (pH 2.5-3.2)에서 2분 이내에 박리되었으나 pH가 낮거나 처리시간이 길어질수록 회복이 느린 것으로 확인되었다. 이상의 결과, 낮은 pH는 전복박리에 유용하게 사용될 수 있으나, 처리시간 및 pH의 농도에 대해 각별한 주의가 요구된다.

• Corrosion Science and Technology
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• 제15권4호
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• pp.159-165
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• 2016

An attempt has been made to understand the influence of retrogression and re-aging (RRA) on the exfoliation corrosion behaviour of AA 7085 alloy in comparison with the peak aged condition (PA). Immersion tests using ASTM G34 and studies involving electrochemical impedance spectroscopy showed that the RRA treated alloy provided higher resistance to exfoliation corrosion than the PA treated alloy. The improved resistance was attributed to the enhanced Cu content and the discontinuous nature of the grain boundary precipitate, which was revealed through transmission electron microscopy.

• 보존과학회지
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• 제22권
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• pp.121-134
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• 2008

석조문화재에서 나타나는 박리현상의 발생메커니즘과 염수용액에 의한 화학적 풍화와 관련된 그 원인을 연구하였다. 박리편에 대하여 화학적, 광물학적, 물리적 분석을 수행하여 함유하고 있는 대표적인 염이 석고임을 밝혔다. 염의 작용을 이해하기 위하여 석고와 더불어 용해도가 상이한 황산나트륨을 공극율이 다른 응회암과 화강암에 처리하였다. $Na_2SO_4$ 처리와 인공풍화를 거친 암석시료들의 모세관물흡수율은 약간 증가하였는데 이는 이 염에 의해 암석의 표면가까이에만 변화가 있었음을 의미한다. Na2SO4는 암석의 표면공극내에서 결정화가 일어나 수화압과 결정압을 발생하여 얇은 박리를 형성하는 것으로 보인다. $CaSO_4{\cdot}2H_2O$는 상대적으로 암석의 내부로 깊이까지 들어가서 집적되므로 집적되는 양이 $Na_2SO_4$ 보다 더 많고, 표면에 집적되는 양보다 내부에 집적되는 양이 많아 물흡수량이 증가하는 결과를 보이는 것이며, 이러한 성질로 인하여 암석에 두꺼운 박리가 야기될 것으로 판단된다. 암석종에 따른 변화에서는 응회암의 경우, 큰 공극율과 높은 모세관물흡수율로 인하여 암석 내부의 깊이까지 들어가서 염이 집적하게 되므로 화강암에 비해 염집적율이 더 크고, 이에 따른 물흡수율이 커서 화강암에 비해 두꺼운 박리현상이 나타날 것으로 보인다. 이에 비해 공극율과 모세관물흡수율이 낮은 화강암에서는 표면부위에서 집중적으로 염의 집적이 일어나서 얇은 박리가 발생하는 것으로 판단된다.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2016년도 제50회 동계 정기학술대회 초록집
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• pp.290.1-290.1
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• 2016

Grapehen, a single atomic layer of graphite, has been in the spotlight and researched in vaious fields, because its fine mechanical, electrical properties, flexibility and transparence. Synthesis methods for large-area graphene such as chemical vaper deposition (CVD) and mechanical, chemical exfoliation have been reported. In particular, chemical exfoliation method receive attention due to low cost process. Chemical exfoliation method require reduction of graphene oxide in the process of exfoliation such as chemical reduction by strong reductant, thermal reduction on high temperature, and optical reduction via ultraviolet light exposure. Among these reduction methods, optical reduction is free from damage by strong reductant and high temperature. However, optical reduction is economically infeasible because the high cost of short-wavelength ultraviolet light sorce. In this paper, we make graphene-oxide and lanthanoid ion mixture aqueous solution which has highly optical absorbency in selective wevelength region. Sequentially, we synthesize reduced graphene oxide (RGO) using the solution and visible laser beam. Concretely, graphene oxide is made by modified hummer's method and mix with 1 ml each ultraviolet ray absorbent Gd3+ ion, Green laser absorbent Tb3+ ion, Red laser absorbent Eu3+ ion. After that, we revivify graphene oxide by laser exposure of 300 ~ 800 nm layser 1mW/cm2 +. We demonstrate reproducibility and repeatability of RGO through FT-IR, UV-VIS, Low temperature PL, SEM, XPS and electrical measurement.

• Maxillofacial Plastic and Reconstructive Surgery
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• 제16권3호
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• pp.515-520
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• 1994

Herpes Zoster is an acute viral infection characterized by the appearance of vesicles that occur on the skin and mucous membrane along the pathway of an involved sensory nerve. Although Herpes zoster is usually as benign viral infection, complications may occur especially when cranial nerves are involved. There are few reports of bony and dental complications by Herpes Zoster infection, all of which were isolated in a single quadrant. These include devitalized teeth, abnormal development of permanent teeth, internal resoption and spontaneous exfoliation of teeth with osteonecrosis of the alveolar bone. No agreement has been reached concerning the pathogenesis of osteonecrosis and tooth exfoliation associated with herpes zoster infection. We recently experienced series of maxillary osteonecrosis and spontaneous teeth exfoliation in patients with Herpes Zoster infection and present two cases with review of literature.