• 한국진공학회:학술대회논문집
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• 한국진공학회 2013년도 제44회 동계 정기학술대회 초록집
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• pp.630-630
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• 2013

Recently, atomically smooth hexagonal boron nitride(h-BN) known as a white graphene has drawn great attention since the discovery of graphene. h-BN is a III-V compound and has a honeycomb structure very similar to graphene with smaller lattice mismatch. Because of strong covalent sp2bonds like graphene, h-BN provides a high thermal conductivity and mechanical strength as well as chemical stability of h-BN superior to graphene. While graphene has a high electrical conductivity, h-BN has a highly dielectric property as an insulator with optical band gap up to 6eV. Similar to the graphene, h-BN can be applied to a variety of field, such as gate dielectric layers/substrate, ultraviolet emitter, transparent membrane, and protective coatings. However, up until recently, obtaining and controlling good quality monolayer h-BN layers have been too difficult and challenging. In this work, we investigate the controlled synthesis of h-BN layers according to the growth condition, time, temperature, and gas partial pressure. h-BN is obtained by using chemical vapor deposition on Cu foil with ammonia borane (BH3NH3) as a source for h-BN. Scanning Transmission Electron Microscopy (STEM, JEOL-JEM-ARM200F) is used for imaging and structural analysis of h-BN layer. Sample's surface morphology is characterized by Field emission scanning electron microscopy (SEM, JEOL JSM-7100F). h-BN is analyzed by Raman spectroscopy (HORIBA, ARAMIS) and its topographic variations by Atomic force microscopy (AFM, Park Systems XE-100).

• International Journal of Stem Cells
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• 제16권3호
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• pp.326-341
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• 2023

Background and Objectives: Osteoarthritis (OA) is a degenerative disease that leads to the progressive destruction of articular cartilage. Current clinical therapeutic strategies are moderately effective at relieving OA-associated pain but cannot induce chondrocyte differentiation or achieve cartilage regeneration. We investigated the ability of wedelolactone, a biologically active natural product that occurs in Eclipta alba (false daisy), to promote chondrogenic differentiation. Methods and Results: Real-time reverse transcription-polymerase chain reaction, immunohistochemical staining, and immunofluorescence staining assays were used to evaluate the effects of wedelolactone on the chondrogenic differentiation of mesenchymal stem cells (MSCs). RNA sequencing, microRNA (miRNA) sequencing, and isobaric tags for relative and absolute quantitation analyses were performed to explore the mechanism by which wedelolactone promotes the chondrogenic differentiation of MSCs. We found that wedelolactone facilitates the chondrogenic differentiation of human induced pluripotent stem cell-derived MSCs and rat bone-marrow MSCs. Moreover, the forkhead box O (FOXO) signaling pathway was upregulated by wedelolactone during chondrogenic differentiation, and a FOXO1 inhibitor attenuated the effect of wedelolactone on chondrocyte differentiation. We determined that wedelolactone reduces enhancer of zeste homolog 2 (EZH2)-mediated histone H3 lysine 27 trimethylation of the promoter region of FOXO1 to upregulate its transcription. Additionally, we found that wedelolactone represses miR-1271-5p expression, and that miR-1271-5p post-transcriptionally suppresses the expression of FOXO1 that is dependent on the binding of miR-1271-5p to the FOXO1 3'-untranscribed region. Conclusions: These results indicate that wedelolactone suppresses the activity of EZH2 to facilitate the chondrogenic differentiation of MSCs by activating the FOXO1 signaling pathway. Wedelolactone may therefore improve cartilage regeneration in diseases characterized by inflammatory tissue destruction, such as OA.

• 한국지구과학회지
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• 제39권3호
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• pp.275-290
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• 2018

본 연구는 과학공학 융합 수업을 통해 학생들의 공학과 공학자에 대한 인식이 어떻게 변화되었는지 알아보기 위한 연구이다. 본 연구에서 사용한 과학공학 융합 수업은 제한된 예산과 시간동안 공학적 문제를 해결하는 24차시 수업으로 설계되었으며 20명의 초등 과학 영재 학생들에게 적용하였다. 본 연구의 주요데이터는 공학자 그림 그리기와 설명문항, 그리고 이에 대한 개별 인터뷰와 초점 집단 면접을 통해 수집되었으며, 공학자 그리기에 대한 설명과 인터뷰는 전사내용을 토대로 양적(빈도분석과 대응표본 t-검증), 질적 분석 방법을 모두 사용하여 분석하였다. 과학공학 융합 수업은 과학 영재 학생들의 공학 설계에 대한 이해에 긍정적인 영향을 미치는 것으로 나타났다. 또한 공학과 공학자, 그리고 공학과 사회의 관계에 대한 인식도 바람직한 방향으로 변화하였다. 공학은 여러 명이 협력하는 사회적인 활동이라는 인식, 그리고 공학자의 윤리의식, 공학의 사회적 가치 등 공학과 사회의 관계에 대한 인식도 바람직하게 변화하였다.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2001년도 춘계학술대회논문집D
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• pp.903-908
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• 2001

A web-based client/server program, MOVIDIK(Motor-Operated-Valve Integrated Database Information of KEPCO) has been developed to perform a design basis safety evaluation for a motor-operated-valve(MOV) in the nuclear power plant. The MOVIDIK consists of seven analysis modules and one administrative module. The analysis module calculates a differential pressure on the valve disk, thrust/torque acting at a valve stem, maximum allowable stress, thermal-overload-relay selection, voltage degradation, actuator output and margin. In addition, the administrative module manages user information, approval system and code information. MOVIDIK controls a huge amount of evaluation data and piles up the safety information of safety-related MOV. The MOVIDIK will improve the efficiency of safety evaluation work and standardize the analysis process for the MOV.

• Smart Structures and Systems
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• 제7권3호
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• pp.213-222
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• 2011

The native extracellular matrix (ECM) consists of an integrated fibrous protein network and proteoglycan-based ground (hydrogel) substance. We designed a novel electrospinning technique to engineer a three dimensional fiber-hydrogel composite that mimics the native ECM structure, is injectable, and has practical macroscale dimensions for clinically relevant tissue defects. In a model system of articular cartilage tissue engineering, the fiber-hydrogel composites enhanced the biological response of adult stem cells, with dynamic mechanical stimulation resulting in near native levels of extracellular matrix. This technology platform was expanded through structural and biochemical modification of the fibers including hydrophilic fibers containing chondroitin sulfate, a significant component of endogenous tissues, and hydrophobic fibers containing ECM microparticles.

• 산업공학
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• 제11권2호
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• pp.211-225
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• 1998

As mentioned in Part I all groupware products have been categorized into three areas which include cooperation/document management systems(CMS), collaborative writing systems(CWS), and decision-making/meeting system(DMS). This study deals with a comparative analysis of the last two areas, which is added to the first. It turns out that DMS has a higher market share than CWS. However. since effective collaboration requires the functions inherent to these two systems. they should be integrated somehow. The systems' functions that have been implemented in response to design issues have been described. Each group of the functions has been divided into three parts which consist of basic function, quasi-basic function. and others. Such a decision has been made according to the frequency rate of the functions provided in the products. While the basic functions in CWS include collaboraive writing beyond restriction of time and place, group awareness. version control. and others, in DMS realtime collaboration. brainstorming. presentation. various task support. policy formation. document management, multimedia, subgroup communication. topic commenter, categorizer, screen capture and various rile transfer. The basic functions are merged into the integrated functional model which was proposed in Part I. Since the model is so flexible that it can partially include the quasi-functions in addition to the hasic functions. a large number of products may stem from the modification of the functional model.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2015년도 제49회 하계 정기학술대회 초록집
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• pp.55-55
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• 2015

Today, engineers are facing new set of challenges that are quite different from the conventional ones. Information technologies are rapidly commoditizing while the paths beyond the current roadmaps became uncertain as various technologies have been pushed to their limits. Along with these changes in IT ecosystems, grand challenges such as global security, health, sustainability, and energy increasingly require trans-disciplinary solutions that go beyond the traditional arenas in STEM (Science, Technology, Engineering and Mathematics). Addressing these needs is shifting engineering education and research to a new paradigm where the emphasis is placed on the consilience for holistic and system level understanding and the convergence of technology with AHSD (arts, humanities, social science, and design). At the center of this evolutionary convergence, nanotechnologies are enabling novel functionalities such as bio-compatibility, flexibility, low power, and sustainability while on a mission to meet scalability and low cost for smart electronics, u-health, sensing networks, and self-sustainable energy systems. This talk introduces the efforts of convergence based on the emerging nano technology tool sets in the newly launched School of Integrated Technology and the Yonsei Institute of Convergence Technology at Yonsei International Campus. While the conventional devices have largely depended upon the inherent material properties, the newer devices are enabled by nanoscale dimensions and structures in increasingly standardized and scalable fabrication platform. Localized surface plasmon resonance in 0 dimensional nano particles and structures leads to subwavelength confinement and enhanced near-field interactions enabling novel field of metal photonics for sensing and integrated photonic applications [1,2]. Unique properties offered by 1 dimensional nanowires and 2 dimensional materials and structures can enable novel electronic, photonic, nano-bio, and biomimetic applications [3-5]. These novel functionalities offered by the emerging nanotechnologies are continuously finding pathways to be part of smart systems to improve the overall quality of life.

• 한국디지털정책학회:학술대회논문집
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• 한국디지털정책학회 2006년도 춘계학술대회
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• pp.379-390
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• 2006

For the domestic digital contents, it is particularly important that the planning and mediating functions should cover the whole industries so that in order for dividends and assistance to reach all the way back to the primary contents-creating level, where economic risks are especially high. A proactive cooperation system or framework between the government, the businesses and research institutions, which would allow for free flow of interaction among these players, can play that role. We can broadly define cooperation frameworks into two; one between the central and the local governments and one among private-sector groups, such as companies, associations and groups. These player sin the framework have differing, sometimes, conflicting views regarding the digital contents industry whether the digital contents should aim for skilled applicability or the abstract or whether the emphasis should rest on public interest or profitability. Immature competition and lack of trust among these players also give rise to such inefficiencies as overlap in investments, inexpertness and inefficient use of resources. We have proposed and realized the National Integrated Cooperation System to bridge these gaps among the major players in the industry. The National Integrated Cooperation System rests on the following major functions. The first major function of the NICS is to decipher any ambiguity that may be embedded in external inputs by stratified role and bias. The second function is to create cooperative groups that will deal with the ambiguities based on its consequent situation. The third is a feedback function that will draw out a new cooperative way by re-feeding the capacities and the conflicts that stem from the existing organizations and strategies into cooperation and adjustment process. Our NICS has compared and evaluated with England and Australia digital content industry models under AHP(Analytic Hierarchy Process) method. NICS has turned out to be well designed and have strong points based on OECD innovation and cooperation criteria.

• 대한의용생체공학회:의공학회지
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• 제40권1호
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• pp.1-6
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• 2019

Human mesenchymal stem cells (hMSC) are multipotent stromal cells that have great potential to differentiate into a variety of cell types such as osteocytes, chondrocytes, and myocytes. Although there have been many studies on their clinical availability, little is known about how intracellular signals can be modulated by topographic features of the extracellular matrix (ECM). In this study, we investigated whether and how microwavy-patterned extracellular matrix (ECM) could affect the signaling activity of focal adhesion kinase (FAK), a key cellular adhesion protein. The fluorescence resonance energy transfer (FRET)-based FAK biosensor-transfected cells are incubated on microwavy-patterned surfaces and then platelet derived growth factor (PDGF) are treated to trigger FAK signals, followed by monitoring through live-cell FRET imaging in real time. As a result, we report that PDGF-induced FAK was highly activated in cells cultured on microwavy-patterned surface with L or M type, while inhibited by H type-patterned surface. In further studies, PDGF-induced FAK signals are regulated by functional support of actin filaments, microtubules, myosin-related proteins, suggesting that PDGF-induced FAK signals in hMSC upon microwavy surfaces are dependent on cytoskeleton (CSK)-actomyosin networks. Thus, our findings not only provide new insight on molecular mechanisms on how FAK signals can be regulated by distinct topographical cues of the ECM, but also may offer advantages in potential applications for regenerative medicine and tissue engineering.

• 공업화학
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• 제31권1호
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• pp.7-12
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• 2020

충북의 북부지역에서 한약재 부산물로서 황기 줄기가 대량 생산되고 있으나, 이러한 부산물들은 특별한 수요처가 없이 밭에 폐기물로 버려지고 있다. 본 연구에서는 이 폐기물을 재활용하고자, 황기 줄기를 사용하여 바이오차를 제조하였다. 이 바이오차를 사용하여 물속에 용해된 카드뮴과 망간 이온의 제거특성을 고찰하였다. 50과 100 mg/L 카드뮴 이온을 처리하기 위하여 흡착 평형 실험이 이루어졌을 때, 카드뮴의 제거효율은 각각 100과 95%를 나타내었다. 또한, 50과 100 mg/L 망간 이온을 제거하기 위하여 5 h의 반응이 이루어졌을 때, 각각 36.1과 37.9 mg/g 최대 흡착량을 얻을 수 있었다. 위의 실험 결과, 카드뮴과 망간 이온의 제거공정에서 황기 줄기 바이오차는 활성탄보다 4배 이상의 흡착량을 나타내었다. 그리고 황기 줄기 바이오차와 활성탄 표면의 화학 구조를 관찰하기 위하여 X-ray photoelectron spectroscopy (XPS)를 분석한 결과, 황기 줄기 바이오차는 활성탄과 비교하여 산소 함량과 O/C의 비율이 각각 2.1과 2.4배 증가함을 알 수 있었다. 또한, 망간 이온의 제거능력을 향상시키기 위하여 온도 변화에 의한 운전이 이루어졌으며, 45 ℃로 4 h에서 흡착 평형에 도달하였으며 50과 100 mg/L 망간 이온은 각각 92, 53%의 제거효율을 나타내었다. 결과적으로 이러한 실험 결과들은 물속에 용해된 카드뮴과 망간 이온을 친환경적이며 경제적으로 처리하는 새로운 제거 기술에 유용하게 사용될 수 있을 것이다.