• The Transactions of The Korean Institute of Electrical Engineers
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• v.62 no.10
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• pp.1436-1443
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• 2013

A variety of studies on imitating the skeletal structure and the gait of legged animals have been done in order to develop walking robots which have an ability to adapt to atypical environments. In this paper, we analyzed the gait of a Bearded dragon lizard using the motion capture system, proposed a calibration scheme of the motion data and generated the trotting gait of a lizard based on the calibrated data. Also, we constructed the dynamic model based on the biometric data of a Bearded dragon lizard and applied the trotting gait of the lizard to the dynamic model. We verified the validity of the gait with the commercial dynamic simulation software.

• Tribology and Lubricants
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• v.26 no.2
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• pp.129-135
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• 2010

Geckos have a unique ability to cling to ceilings and walls utilizing dry adhesion. Their foot pads are covered by a large number of small hairs (setae) that contain many branches per seta with a lower level of spatulae. Their fibrillar structure is the primary source of high adhesion. In this study, we construct the adhesion design database for biomimetic adhesive system. A simple idealized fibrillar structure consisting of single array of beams is modeled. The fibers are assumed as oriented cylindrical cantilever beams with spherical tip. We consider three necessary conditions; buckling, fracture and sticking of fiber structure, which constrain the allowed geometry. The adhesion analysis is performed for the attachment system in contact with rough surfaces with different s values for different main design variables-fiber radius, aspect ratio and material elastic modulus and so on. The developed adhesion design databases are useful for understanding biological systems and for guiding of fabrication of the biomimetic attachment system.

• Elastomers and Composites
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• v.44 no.2
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• pp.112-115
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• 2009

In nature, some creatures have the ability to walk vertically or upside down on various natural surfaces. One of them, Tokay Gecko has billions of nano-hair at the epidermis of its digital. These nano hairs makes atomistic attractive force to the surface, therefore, it could walk and run on the vertical or upside surfaces. Recently, many researchers tried to fabricate the dry adhesive structure mimicking the nano-hair structure. in this study, I tried to survey these studies to discuss the direction of future fabrication works of dry adhesive structures.

• Korean Journal of Environmental Biology
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• v.25 no.2
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• pp.124-138
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• 2007

In order to characterize the current status and distribution of reptiles currently inhabiting the Republic of Korea, the results of survey data were analyzed in this study. The results of this analysis showed that the reptiles were distributed into two orders, seven families, and 21 species, with the exception of six marine reptiles, including Dermochelys coriacea schlegelii, Chelonia mydas japonica, Caretta caretta, Hydrophis melanocephalus, Hydrophis cyanocinctus, and Pelamis platrrus. Also, the taxonomic revisions of several species were suggested, although this would be ill-advised before further studies can be conducted regarding the current status of marine reptiles in the region.

• Korean Journal of Environment and Ecology
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• v.34 no.2
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• pp.106-114
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• 2020

The development of transportation and the expansion of the pet market has become the main causes of the increase in the cross-border migration of non-native species. Moreover, recent sales over the Internet were a factor that has promoted pet trades. While the import of non-native species has been steadily increasing in the Republic of Korea, it is not clear how these imported species are traded and how large the trade is. Considering that most of the non-native species found in the wild are the results of release by humans understanding the present situation of pet trades can identify potential non-native species that can enter the wild. This study surveyed the number of species, frequency, and prices of non-native amphibians and reptiles sold in 25 online pet shops from January 22 to February 10, 2019. The results of the survey showed that a total of 677 species of non-native amphibians and reptiles were sold, and the Squamata group accounted for the largest part of them at 65.4% (443 species). The number of non-native amphibians and reptiles sold in online pet shops in 2019 was 2.1 times larger than the 325 species officially imported in 2015. The non-native amphibians and reptiles sold in most pet shops were Litoria caerulea (21 shops) and Correlophus ciliatus (24 shops). The lowest price for non-native amphibians and reptiles was 3,000 won, and the highest price was 100 million won for Rhacodactylus leachianus of Squamata. Among the non-native amphibians and reptiles sold in online pet shops, 11 species were found in the wild and were sold at relatively low prices. We confirmed that Mauremys reevesii, an endangered species class II and natural monument no. 453, and American bullfrogs (albino), an ecosystem disturbing species, were being sold in online pet shops. Moreover, 21.6% of the 677 non-native amphibians and reptiles sold in online pet shops were species designated as CITES. The results of this study can be the important reference data for understanding the status of non-native amphibians and reptiles that are imported and sold in Korea and evaluating and predicting the potential for them to enter the wild.

• Korean Journal of Environment and Ecology
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• v.11 no.1
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• pp.84-99
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• 1997

Amphibian and Reptilian specimens which were surveyed in Gyebangsan during both from Apr. 26, 1995 to Oct. 15, 1995 and from Apr. 13, 1996 to July 28, 1996 were observed 9 Species in 5 Families on 2 Orders and 10 Species in 3 Families, 5 Fimilies, 9 Species and Reptiles were 2 Suborders, 3 Families on 2 Suborders, respectively. Bombina orientalis was revealed dominant species and Bufo stejnegeri was distributed abundant on this investigation area than other survey studies. Relatively large number of larvae of Rana dybowskii were found among the stream and small ponds at the Suchung-gol valley. There were 5 species of Specific wildlife species in Korea as Hynobius leechii, Rana dybowskii, Onchodactylus fischeri, Bufo stejnegeri and Bufo bufo gargarizans. Meanwhile Bufo stejnegeri were endemic species in Korea. 6 Species among 10 Species which were observed Reptiles in this survey Scincella laterale laterale, Dinodon rufozonatus rufozonatus, Agkistrodon brevicaudus, Agkistrodon saxatilis, Amphiesma vibakari ruthveni and Enhydris rufodorsata were Specific wildlife in Korea. Scincella laterale laterale and Takydromus amuriensis were habitated very abundant in Suchung-gol region. Habitat density of Takydromus amureinsis at Suchung-gol region was 36 individuals/ha. Total number of pressed to death individuals caused by press on the road from May to July, 1995 were 404 specimens in 10 Species. The 1,2,3 and 4 Stations where were found the largest number of death individuals caused by press on the road should considered to construct Eco-corridor to reduced the death individuals with small pipes beneath the road as a migration route. Onchodactylus fischeri have around 500m as moving distance and home range for lifelong and it were the climax of broad-leaved tree and highly moisture area that abundantly region of Onchodactylus fischeri.

• Korean Journal of Environmental Biology
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• v.18 no.1
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• pp.113-120
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• 2000

Herpetofauna biodiversity was surveyed at the Chin-do. The results are as follows: During census periods presence of 2 orders, 4 families, 6 species of amphibians and 1 order, 2 suborders, 4 families, 8 species of reptiles were observed or found indirectly by auditorial recording from residents at the Chin-do. Among them 1 protected wildlife(Agkistrodon saxatilis) and several rare species such as Takydromus wolteri, Sciucella laterale laterale and Zamenis spinalis were indentified. Rana nigromaculata and Rana catesbeiana were found in all surveyed areas. Dominant amphibian species was Rana rugosa (D'= 25.8%) and reptile was Takydromus wolteri (D'= 21.8%). Among 4 areas survey area, Uisin-myon showed the highest level of species richness, diversity, and evenness indices (R'= 2.393, H'= 1.931, and E'= 0.7772, respectively). The species richness of Kunnae-myon was lower (R'= 0.932) than other surveyed regions. Based on the frequency of occurrence (85.71%), habitation density of Rana catesbeiana was very common in Chin-do, suggesting that spreading of this foreign species in the entire Korean peninsula. Scincella laterale laterale, Elaphe dione, Elaphe rufodorsata, Dinodon rufozonatus rufozonatus, Rhabdophis tigrinus tigrinus, Agkistrodon ussuriensis, and Zamenis spinalis showed low frequency of occurrence ( < 10%) and efforts to protect them are required. [Herpetofauna, Bio-diversity, Chin-Do].

• Transactions of the Korean Society of Mechanical Engineers A
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• v.40 no.7
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• pp.673-677
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• 2016

Recently, engineering applications have started to adopt solutions inspired by nature. The peculiar adhesive properties of gecko skin are an example, as they allow the animal to move freely on vertical walls and even on ceilings. The high adhesive forces between gecko feet and walls are due to the hierarchical microscopical structure of the skin. In this study, the effect of metal coatings on the adhesive strength of synthetic, hierarchically structured, dry adhesives was investigated. Synthetic dry adhesives were fabricated using PDMS micro-molds prepared by photolithography. Metal coatings on synthetic dry adhesives were formed by plasma sputtering. Adhesive strength was measured by pure shear tests. The highest adhesion strengths were found with coatings composed of 4 nm thick layers of Indium, 8 nm thick layers of Zinc and 6 nm thick layers of Gold, respectively.

• Proceedings of the Korean Vacuum Society Conference
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• 2016.02a
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• pp.141.2-141.2
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• 2016

디스플레이, 센서 등 전자소자는 소형화 단계를 지나 인체 부착형 소자로의 발전을 요구하고 있다. 인체 부착을 위해서는 민감한 피부에 장시간 부착시 무해성과 탈부착의 자유로움이 요구되기에 기존의 화학물질을 활용한 접착 방식에서 개코도마뱀 또는 딱정벌레 발바닥에서 영감을 얻은 자연모사형 건식 접착 방식에 대한 연구가 활발하게 진행되고 있다. 폴리머를 이용하여 자연모사형 마이크로/나노구조 형성은 기계적으로 가공된 금형 몰딩과 후처리를 통한 매우 복잡한 공정이 요구된다. 본 연구에서는 이러한 복잡한 공정을 단순화하기 위해서 폴리머 소재에 플라즈마를 활용한 나노구조를 형성하는 방법을 소개하고자 하며, 건식 접착용 폴리머 소재(PMMA, PDMS)에 따른 표면구조 변화와 표면에너지 변화에 대한 연구를 수행하였다. 플라즈마 표면처리를 위해서 본 연구실에서 자체 개발한 선형이온소스를 활용하였으며 입사에너지, 노출시간, 사용가스에 따른 표면형상 변화를 주사전자현미경을 활용하여 관찰하였다. 또한 처리조건에 따른 표면에너지 변화를 확인하기 위해 물접촉각 변화를 측정하였다. PMMA는 입사에너지, 노출시간이 증가함에 따라 쉽게 나노기둥구조가 형성되었으나, 과도한 입사에너지 또는 노출시간에서는 표면구조가 에칭되면서 무너지는 것이 관찰되었다. 또한 PDMS는 동일한 조건에서 주름구조 형태를 보였으며 노출시간이 증가할수록 주름구조의 간격이 늘어남을 확인하였다. 본 연구 결과를 통해 나노 구조를 쉽게 제어할 수 있는 PMMA가 피부 부착형 접착 패치에 응용이 가능할 것으로 기대된다.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.02a
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• pp.167-167
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• 2013

최근 발수 특성은 자동차 표면, 건축 구조물, 가전제품 및 모바일 기기 등 여러 분야에서 사용되고 점차 그 필요성이 대두되고 있다. 이러한 발수성의 표면은 연 잎이나 곤충의 날개, 도마뱀의 발바닥 등 자연계의 여러 곳에서 관찰 할 수 있다. 특히 연 잎의 표면에서 나타나는 초발수 특성이 마이크로와 나노 크기의 돌기 구조와 표피 왁스 성분에 기인한다는 것이 밝혀지면서 이를 응용한 다양한 연구가 진행되고 있다. 본 연구에서는 물리적인 표면처리로 마이크로와 나노 구조물을 형성하고 그 위에 표면에너지를 낮출 수 있는 물질을 증착하여, 발수 특성을 가지는 표면을 개발하였다. 알루미늄 표면에 마이크로 크기의 알루미나(Al2O3) 분말을 이용한 블라스트(blast) 공정으로 마이크로 구조를 형성하고, 선형 이온 소스(LIS)를 이용한 Ar 이온 빔 에칭으로 나노 구조를 형성하였다. FE-SEM 분석을 통해 수~수십 마이크로 구조 위에 나노 크기의 구조가 형성 된 것을 관찰하였다. 마이크로와 나노 구조가 형성된 알루미늄의 표면에너지를 낮추기 위해 trimethylsilane (TMS) 및 Ar을 이용한 플라즈마처리로 표면에 기능성 코팅막을 형성하였다. 그 결과 TMS처리 전에 비해 표면에너지가 99.75 mJ/m2에서 9.05 mJ/m2으로 급격히 낮아지고 접촉각이 $54^{\circ}$에서 $123^{\circ}$로 향상되었다.