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휴먼형 로봇 손의 사물 조작 수행을 이용한 인간 행동 복제 강화학습 정책 최적화 방법 성능 평가
박나현 ( Na Hyeon Park ),오지헌 ( Ji Heon Oh ),류가현 ( Ga Hyun Ryu ),( Edwin Valarezo Añazco ),( Patricio Rivera Lopez ),원다슬 ( Da Seul Won ),정진균 ( Jin Gyun Jeong ),장윤정 ( Yun Jung Chang ),김태성 ( Tae-seong Kim ) 한국정보처리학회 2020 한국정보처리학회 학술대회논문집 Vol.27 No.2
로봇이 사람과 같이 다양하고 복잡한 사물 조작을 하기 위해서 휴먼형 로봇손의 사물 파지 작업이 필수적이다. 자유도 (Degree of Freedom, DoF)가 높은 휴먼형(anthropomorphic) 로봇손을 학습시키기 위하여 사람 데모(human demonstration)가 결합된 강화학습 최적화 방법이 제안되었다. 본 연구에서는 강화학습 최적화 방법에 사람 데모가 결합된 Demonstration Augmented Natural Policy Gradient (DA-NPG)와 NPG 의 성능 비교를 통하여 행동 복제의 효율성을 확인하고, DA-NPG, DA-Trust Region Policy Optimization (DA-TRPO), DA-Proximal Policy Optimization (DA-PPO)의 최적화 방법의 성능 평가를 위하여 6 종의 물체에 대한 휴먼형 로봇손의 사물 조작 작업을 수행한다. 그 결과, DA-NPG 와 NPG를 비교한 결과를 통해 휴먼형 로봇손의 사물 조작 강화학습에 행동 복제가 효율적임을 증명하였다. 또한, DA-NPG 는 DA-TRPO 와 유사한 성능을 보이면서 모든 물체에 대한 사물 파지에 성공하여 가장 안정적이었다. 반면, DA-TRPO 와 DA-PPO 는 사물 조작에 실패한 물체가 존재하여 불안정한 성능을 보였다. 본 연구에서 제안하는 방법은 향후 실제 휴먼형 로봇에 적용하여 휴먼형 로봇 손의 사물조작 지능 개발에 유용할 것으로 전망된다.
행동 복제 강화학습 및 딥러닝 사물 부분 검출 기술에 기반한 사람형 로봇손의 사물 조작
오지헌 ( Ji Heon Oh ),류가현 ( Ga Hyun Ryu ),박나현 ( Na Hyeon Park ),( Edwin Valarezo Añazco ),( Patricio Rivera Lopez ),원다슬 ( Da Seul Won ),정진균 ( Jin Gyun Jeong ),장윤정 ( Yun Jung Chang ),김태성 ( Tae-seong Kim ) 한국정보처리학회 2020 한국정보처리학회 학술대회논문집 Vol.27 No.2
최근 사람형(Anthropomorphic)로봇손의 사물조작 지능을 개발하기 위하여 행동복제(Behavior Cloning) Deep Reinforcement Learning(DRL) 연구가 진행중이다. 자유도(Degree of Freedom, DOF)가 높은 사람형 로봇손의 학습 문제점을 개선하기 위하여, 행동 복제를 통한 Human Demonstration Augmented(DA)강화 학습을 통하여 사람처럼 사물을 조작하는 지능을 학습시킬 수 있다. 그러나 사물 조작에 있어, 의미 있는 파지를 위해서는 사물의 특정 부위를 인식하고 파지하는 방법이 필수적이다. 본 연구에서는 딥러닝 YOLO 기술을 적용하여 사물의 특정 부위를 인식하고, DA-DRL 을 적용하여, 사물의 특정 부분을 파지하는 딥러닝 학습 기술을 제안하고, 2 종 사물(망치 및 칼)의 손잡이 부분을 인식하고 파지하여 검증한다. 본 연구에서 제안하는 학습방법은 사람과 상호작용하거나 도구를 용도에 맞게 사용해야하는 분야에서 유용할 것이다.
Kim, Da-Seul,Hwang, Nong-Moon IOP 2018 Journal of Physics. D, Applied Physics Vol.51 No.46
<P>Nonclassical crystallization is the process in which crystals grow by deposition of nanoparticles rather than by the layer-wise deposition of atoms/ions/molecules on a crystal surface. A spontaneous generation of charged nanoparticles (CNPs) in the gas phase has been experimentally confirmed during many chemical vapor deposition (CVD) processes. The fact that crystals grown by CNPs have smooth surfaces without any void indicates that CNPs have a liquid-like or superplastic property. Based on this understanding of nonclassical crystallization in CVD processes, the synthesis of nanoparticles, thin films and nanowires can be approached systematically. Since electrical field, drag effect, size and the number of charges per particle affect the behavior of CNPs, electric bias, gas velocity, the size of the nanoparticles and the amount of charge can be new processing parameters. The size distribution of CNPs depends on the process conditions.</P> <P>The nanoparticles can be attracted or repelled by applying an electric bias to a substrate. If the nanoparticles are made to land on the substrate in a suitable number density, they can be used as quantum dots. In addition, nanopowders, nanowires, and nanostructures can be synthesized by CNPs with or without metallic catalysts on substrates. Herein, we will review recent results of the synthesis of nanostructures such as nanoparticles, thin films, and nanowires in the CVD process. We will also discuss the role of charge in these syntheses.</P>
Da-Hyun Kim,Seul Lee,Hyeok Gu Kang,박현우,이한웅,Dongin Kim,Dong-Hoon Yoem,Jin-Hyung Ahn,Eunsin Ha,Weon-Kyoo You,Sang Hoon Lee,김석준,전경희 생화학분자생물학회 2020 BMB Reports Vol.53 No.10
Notch signaling has been identified as a critical pathway in gastric cancer (GC) progression and metastasis, and inhibition of Delta-like ligand 4 (DLL4), a Notch ligand, is suggested as a potent therapeutic approach for GC. Expression of both DLL4 and vascular endothelial growth factor receptor 2 (VEGFR2) was similar in the malignant tissues of GC patients. We focused on vascular endothelial growth factor (VEGF), a known angiogenesis regulator and activator of DLL4. Here, we used ABL001, a DLL4/VEGF bispecific therapeutic antibody, and investigated its therapeutic effect in GC. Treatment with human DLL4 therapeutic antibody (anti-hDLL4) or ABL001 slightly reduced GC cell growth in monolayer culture; however, they significantly inhibited cell growth in 3D-culture, suggesting a reduction in the cancer stem cell population. Treatment with anti-hDLL4 or ABL001 also decreased GC cell migration and invasion. Moreover, the combined treatment of irinotecan with anti-hDLL4 or ABL001 showed synergistic antitumor activity. Both combination treatments further reduced cell growth in 3D-culture as well as cell invasion. Interestingly, the combination treatment of ABL001 with irinotecan synergistically reduced the GC burden in both xenograft and orthotopic mouse models. Collectively, DLL4 inhibition significantly decreased cell motility and stem-like phenotype and the combination treatment of DLL4/VEGF bispecific therapeutic antibody with irinotecan synergistically reduced the GC burden in mouse models. Our data suggest that ABL001 potentially represents a potent agent in GC therapy. Further biochemical and pre-clinical studies are needed for its application in the clinic.
Kim Da Seul,Park Jong Eun,황승연,Jeong Daun,Lee Guntak,Kim Taerim,Lee Se Uk,Yoon Hee,Cha Won Chul,심민섭,Jo Ik Joon,Shin Tae Gun 대한응급의학회 2022 Clinical and Experimental Emergency Medicine Vol.9 No.3
Objective We evaluated the performance of diastolic shock index (DSI) and lactate in predicting vasopressor requirement among hypotensive patients with suspected infection in an emergency department. Methods This was a single-center, retrospective observational study for adult patients with suspected infection and hypotension in the emergency department from 2018 to 2019. The study population was split into derivation and validation cohorts (70/30). We derived a simple risk score to predict vasopressor requirement using DSI and lactate cutoff values determined by Youden index. We tested the score by the area under the receiver operating characteristic curve (AUC). We performed a multivariable regression analysis to evaluate the association between the timing of vasopressor treatment and 28-day mortality. Results A total of 1,917 patients were included. We developed a score, assigning 1 point each for the high DSI (≥2.0) and high lactate (≥2.5 mmol/L) criteria. The AUCs of the score were 0.741 (95% confidence interval [CI], 0.715–0.768) at hypotension and 0.736 (95% CI, 0.708–0.763) after initial fluid challenge in the derivation cohort and 0.676 (95% CI, 0.631–0.719) at hypotension and 0.688 (95% CI, 0.642–0.733) after initial fluid challenge in the validation cohort, respectively. In patients with scores of 2 points, early vasopressor therapy initiation was significantly associated with decreased 28-day mortality (adjusted odds ratio, 0.37; 95% CI, 0.14–0.94). Conclusion A prediction model with DSI and lactate levels might be useful to identify patients who are more likely to need vasopressor administration among hypotensive patients with suspected infection.