위상평면을 이용한 유압식 이족 휴머노이드 로봇의 보행제어

최동일(Dongil Choi),김정훈(Jung-Hoon Kim),김정엽(Jung-Yup Kim) 제어로봇시스템학회 2011 제어·로봇·시스템학회 논문지 Vol.17 No.3

This paper proposes a novel control method using phase plane for a hycraulic biped humanoid robot. In biped walking control, it is much more difficult to control the posture of a biped robot in the coronal plane because the supporting area formed by the both feet in the coronal plane is much narrower than that of the sagittal plane. When the biped robot walks stably, the phase portrait of the pelvis in the coronal plane makes an elliptical shape. From this point of view, we develop an ankle torque controller and a foot placement controller for tracking the desired phase portrait during walking. We design these controllers by using simulations of a simplified compass gait biped model to regulate the desired portrait of pelvis. The effectiveness of the proposed control method is proved through full-body dynamic walking simulations and real experiments of the SARCOS hydraulic biped humanoid.

간세포암의 고주파열치료의 최신 기술적 발전들

최동일 ( Dong Il Choi ),임현철 ( Hyun Chul Rhim ),이민우 ( Min Woo Lee ) 대한간암학회 2012 대한간암학회지 Vol.12 No.1

Lots of recent technical advances in radiofrequency ablation (RFA) of hepatocellular carcinoma (HCC) have introduced. First, contrast-enhanced ultrasound can help to detect the index tumors, residual tumor, and local recurrence. After contrast-enhanced ultrasound for subtle small tumors, we can perform RFA with high confidence. The use of artificial ascites in RFA is a simple and useful technique to minimize collateral thermal injury and to improve the sonic window. Fusion imaging between US and CT or MR during RFA is useful since US can provide real-time imaging and CT or MR provides high quality images with good contrast and spatial resolution. RFA can be performed with fluoroscopy guidance to lipiodol retention tumors.

동해 남부 해역 퇴적물과 저층 해수 세균 군집 조성의 계절적 변화 연구

최동한,김병모,최태섭,이정석,노재훈,박영규,강성길,Choi, Dong Han,Gim, Byeong-Mo,Choi, Tae Seob,Lee, Jung-Suk,Noh, Jae Hoon,Park, Young-Gyu,Kang, Seong-Gil 한국해양학회 2014 바다 Vol.19 No.2

해양 환경에서 세균은 다양한 생지화학적 순환에 있어서 중요한 역할을 수행하고 있으며, 그들의 다양성에 대한 정보는 생태계에서 세균의 생지화학적 기능을 이해하는데 중요하다. 본 연구는 $CO_2$ 해양지중저장의 후보지인 동해 남부해역의 표층 퇴적물과 퇴적물 위의 저층 해수에서 최신 연구 기법인 pyrosequencing을 통하여 세균의 계절적 다양성을 분석함으로써, 동해 퇴적물 세균상의 특성을 이해하고자 하였다. 퇴적물에서는 대부분의 시기에 Gammaproteobacteria가 우점한 반면, 저층 해수에서는 Alphaproteobacteria가 우점하여 두 서식처에서 세균의 다양성은 큰 차이를 보였다. 또한 속 수준의 다양성 분석에서도 저층 해수에서는 대부분의 시기에 SAR11 그룹에 속하는 Pelagibacter가 가장 우점한 반면, 퇴적물 시료에서는 Gammaproteobacteria에 속하는 미동정 속이 가장 우점하였다. 그러나 두 서식처 모두에서 5% 이상의 점유율을 보인 속의 수는 10 속 미만으로 소수였으며, 낮은 점유율을 갖는 많은 종류의 세균들이 군집 내에 공존하는 공통적인 특성이 나타났다. 본 연구의 세균 다양성 연구는 동해 저층 해수 및 퇴적물의 세균 다양성에 대한 특성의 이해와 더불어 $CO_2$ 해양지중저장 사업의 진행에 따른 세균의 다양성 및 기능 변화에 대한 사전 자료 및 해역이용영향평가 배경 자료로 활용될 수 있을 것이다. Bacteria play an important role in biogeochemical cycles in marine environments and their functional attributes in ecosystems depend primarily on species composition. In this study, seasonal variation of bacterial diversity was investigated by pyrosequencing of 16S rDNA in surface sediment and overlying seawater collected in the south East Sea, planned for the site of $CO_2$ sequestration by the carbon capture and storage (CCS) project. Gammaproteobacteria was dominant in the sediment in most seasons, whereas Alphaproteobacteria was a most dominant group in the overlying water. Thus, the bacterial diversity greatly differ between sediment and seawater samples. On the genus level, bacterial diversity between two habitats was also different. However, the number of genera found over 5% were less than 10 in both habitats and the bacterial community was composed of a number of diverse minor or rare genera. Elevation of $CO_2$ concentration during a $CO_2$ storage process, could result in change of bacterial diversity. Thus, this study will be very useful to access the effect of $CO_2$ on bacterial diversity and to predict functional change of the ecosystem during the process of CCS project.

신경섬유종증 환자에 발생한 거대 악성말초신경초종의 치험례

최동일,서동국,조우성,정철훈,조성진 대한성형외과학회 2006 Archives of Plastic Surgery Vol.33 No.6

Purpose: Malignant peripheral nerve sheath tumors most often arise from the anatomically discernible peripheral nerve or neurofibroma.Methods: A 55-year-old man had a rapidly growing pedunculated large mass on the sacrolumbar junction for 2 years. He has congenital neurofibromatosis type I. He had multiple caf-au-lait spots and multiple neurofibromas on the entire body. The mass developed from a subcutaneous nodule on the sacrolumbar junction and grew rapidly. The preoperative punch biopsy revealed a malignant peripheral nerve tumor. The mass was completely excised with 1cm free margin above the deep fascial plane. Results: There was no evidence of recurrence of tumor for 19 months of follow-up examination.Conclusion: Malignant peripheral nerve sheath tumor is very rare and has unique feature. We report a successful case of malignant peripheral nerve sheath tumor with the review of the literatures.

열대 홍수림 주변 해역 환경 전이대의 식물플랑크톤 및 박테리아의 분포

최동한,노재훈,안성민,이미진,김동선,김경태,권문상,박흥식 한국해양과학기술원 2013 Ocean and Polar Research Vol.35 No.4

In order to understand phytoplankton and bacterial distribution in tropical coral reef ecosystems in relation to the mangrove community, their biomass and activities were measured in the sea waters of the Chuuk and the Kosrae lagoons located in Micronesia. Chlorophyll a and bacterial abundance showed maximal values in the seawater near the mangrove forests, and then steeply decreased as the distance increased from the mangrove forests, indicating that environmental conditions for these microorganisms changed greatly in lagoon waters. Together with chlorophyll a, abundance of Synechococcus and phototrophic picoeukaryotes and a variety of indicator pigments for dinoflagellates, diatoms, green algae and cryptophytes also showed similar spatial distribution patterns, suggesting that phytoplankton assemblages respond to the environmental gradient by changing community compositions. In addition, primary production and bacterial production were also highest in the bay surrounded by mangrove forest and lowest outside of the lagoon. These results suggest that mangrove waters play an important role in energy production and nutrient cycling in tropical coasts, undoubtedly receiving large inputs of organic matter from shore vegetation such as mangroves. However, the steep decrease of biomass and production of phytoplankton and heterotrophic bacteria within a short distance from the bay to the level of oligotrophic waters indicates that the effect of mangrove waters does not extend far away.

섬피판들을 이용한 무릎 이하 부위 재건

최동일,정철훈,이종욱,김진왕 대한성형외과학회 2008 Archives of Plastic Surgery Vol.35 No.3

Purpose: The lower leg often has poor vascularity, proximity to bone, and insufficient soft tissue. The island flaps offer a feasible one stage reconstruction and has a remarkable vascularization and high quality results for soft tissue defect with or without bony problems to occur on regions below the knee. So we reported our experience of island flaps with review of the literatures.Methods: We reconstructed 29 cases of soft tissue and 2 cases of bony defect on regions below the knee by using various island flaps at our hospital from December, 1991 to January, 2006. We used 2 fibular osteocutaneous island flaps, 15 reverse sural island flaps, 6 extensor digitorum brevis muscular island flaps, 2 medial plantar island flaps, 5 saphenous island flaps, and a dorsalis pedis island flap.Results: Partial necrosis was developed in 4 out of 15 reverse sural island flaps and 1 out of 5 saphenous island flaps, but they were healed with secondary skin graft. There was partial loss of skin graft on the donor sites in 2 cases.Conclusion: Island flaps are very useful for reconstruction of regions below the knee because island flaps have good vascularity and less risk of infection. Generous flap size, easy operative technique, lower cost, shorter operative time, and minimal morbidity at the donor site are other advantages. We attained satisfactory results.

해양미생물의 세계 - '바다 + 어패류'와 콜레라

최동한,Choe, Dong-Han 한국과학기술단체총연합회 2002 과학과 기술 Vol.35 No.8

콜레라균은 0.3~3%의 염분에서 살 수 있으며 2% 정도의 염분에서 최적성장한다. 콜레라의 감염경로는 굴, 게, 및 생선 등 어패류를 날 것으로 섭취할 때 발생된다.

Adhesive Strength Between Metal Plated with Inorganic Particles and Polycarbonates

최동해,손현명,류민영 한국고분자학회 2022 Macromolecular Research Vol.30 No.12

Insert molding is used to manufacture products that combine metal and plastic. In this study, a special treatment was performed on the metal surface, and insert molding was performed to improve bonding strength between the metal and plastic. The metal surface treatment method involved nickel plating using inorganic particles. The type and size of particles and the height of plating were controlled. Artificial diamond and aluminum oxide were used as the particles, and the plating heights were 1/2, 1/3, and 1/4 of the particle size. Insert molding was performed with polycarbonate (PC) and PC containing glass fiber (GF), and a surface-treated metal sheet before plating. Then the adhesive strength of the metal and plastic specimens was measured. The adhesive strength varied according to the plating height and particle size, and the larger the particle size, the higher the bonding strength. The adhesive strength of the PC containing GF was 25% higher than the PC without GF. The metal surface treated by plating using aluminum oxide particles had better adhesive strength than the artificial diamond particles.

SAN으로 코팅된 PC/PTFE 복합체의 기계적 물성 및 난연특성

최동인(Dong In Choi),이영실(Young Sil Lee),윤관한(Kwan Han Yoon),김수완(Soo Wan Kim),하두한(Doo Han Ha) 한국고분자학회 2020 폴리머 Vol.44 No.6

본 연구에서는 스티렌(styrene)과 아크릴로니트릴(acrylonitrile)을 공중합하여 형성된 SAN을 폴리테트라플루오로에틸렌(PTFE) 입자의 표면에 코팅하여 core-shell 구조를 갖는 SAN-PTFE 나노 입자를 제조한 후 이를 폴리카보네이트(PC)에 분산시키기 위해 압출기를 이용하여 복합체를 제조하였다. SAN 중합용 개시제의 함량이 줄어들면 PTFE에 코팅된 SAN의 두께가 감소하였고 중합 시 PTFE의 함량을 늘려주면 역시 SAN 코팅 두께가 감소하였으며, 중합시간을 늘려주면 코팅 두께는 증가하였다. PTFE 8.3 phr을 함유하는 PC/SAN-PTFE 복합체의 경우 인장강도와 충격강도는 PC와 같은 57 MPa과 48 J/m이 얻어졌고 인장탄성률은 오히려 PC보다 7% 증가하였다. 그러나 PTFE를 포함하는 PC/PTFE 복합체의 경우는 충격강도를 제외하고 인장강도와 인장탄성률 모두 PC의 값보다 감소하였다. PTFE 8.3 phr을 함유하는 PC/SAN-PTFE 복합체의 한계산소지수(LOI)는 28.1%를 나타내었다. Core-shell structured SAN-PTFE composites were prepared by grafting styrene and acrylonitrile copolymer (SAN) onto the surface of polytetrafluoroethylene (PTFE) and compounded with polycarbonate (PC) using co-rotating twin extruder. Coating thickness of the shell decreased with decreasing of initiator and increasing of PTFE content, and increased with the polymerization time of SAN copolymer. The tensile and impact strength of PC/SAN-PTFE (8.3 phr) composite were 57 MPa and 48 J/m, respectively, which are similar values of PC. The tensile modulus of the composite was rather 7% higher than that of PC. However, the tensile strength and modulus of PC/PTFE composite were lower than those of PC while the impact strength of PC/PTFE was maintained as almost same value of PC. The limiting oxygen index (LOI) of PC/SAN-PTFE composite containing 8.3 phr of PTFE was determined to be 28.1%.

해양미생물의 세계 - 환경변화에 민감한 바닷속의 미생물들

최동한,Choe, Dong-Han 한국과학기술단체총연합회 2002 과학과 기술 Vol.35 No.12

해양에서 박테리아는 식물플랑크톤이 만들어낸 유기물질을 이용하여 성장하고 이 박테리아는 편모가 달린 원생동물에 잡아 먹힌다. 또 이 원생동물은 더 큰 섬모충류에게 먹히고 섬모충류는 플랑크톤의 먹이가 된다. 이러한 해양미생물체계에 환경변화가 있으면 생태학적 교란이 발생하여 바다의 오염 등 환경을 악화시킨다.