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목분 충진 고분자 용융체의 압출다이 내 유동 및 열전달에 관한 수치해석
고승환,박형규,송명호,김찬중,Ko, Seung-Hwan,Park, Hyung-Gyu,Song, Myung-Ho,Kim, Charn-Jung 대한기계학회 2003 大韓機械學會論文集B Vol.27 No.2
A three-dimensional numerical analysis of the flow and heat transfer characteristic of wood-flour-filled polypropylene melt in an extrusion die was carried out. Used for this analysis were Finite Concept Method based on FVM, unstructured grid and non-Newtonian fluid viscosity model. Temperature and flow fields are closely coupled through temperature dependent viscosity and viscous dissipation. With large Peclet, Nahme, Brinkman numbers, viscous heating caused high temperature belt near die housing. Changing taper plate thickness and examining some predefined parameters at die exit investigated the effect of taper plate on velocity and temperature uniformities. In the presence of taper plate, uniformity at die exit could be improved and there existed an optimum thickness to maximize it.
목분 충진 고분자 용융체의 압출다이 내 유동 및 열전달에 관한 수치해석
고승환(Seung Hwan Ko),박형규(Hyung Gyu Park),송명호(Myungho Song),김찬중(Cham-Jung Kim) 대한기계학회 2001 대한기계학회 춘추학술대회 Vol.2001 No.9
A three-dimensional numerical analysis of the flow and heat transfer characteristic of wood-flour-filled polypropylene melt in an extrusion die was carried out. Used for this analysis were Finite Concept Method based on FVM, unstructured grid and non-Newtonian fluid viscosity model. Temperature and flow fields are closely coupled through temperature dependent viscosity and viscous dissipation. With large Peclet, Nahme, Brinkman numbers, viscous heating caused high temperature belt near die housing. Changing taper plate thickness and examining some predefined parameters at die exit investigated the effect of taper plate on velocity and temperature uniformities. In the presence of taper plate, uniformity at die exit could be improved and there existed an optimum thickness to maximize it.
레이저 유도 국소 열수화학반응으로 성장된 ZnO 나노 와이어 UV 센서 배열의 저온에서 신속한 제작
고승환(Seung Hwan Ko),조현민(Hyunmin Cho),홍석준(Sukjoon Hong),여준엽(Junyob Yeo) 대한기계학회 2014 대한기계학회 춘추학술대회 Vol.2014 No.11
We demonstrate ZnO nanowire based UV sensor by laser-induced hydrothermal growth of ZnO nanowire. By inducing a localized temperature rise using focused laser, ZnO nanowire array at ∼15 μm size consists of individual nanowires with ∼8 μm length and 200∼400 nm diameter is readily synthesized on gold electrode within 30 min at the desired position. The laser-induced growth process is consecutively applied on two different points to bridge the micron gap between the electrodes. The resultant photoconductive ZnO NW interconnections display 2∼3 orders increase in the current upon the UV exposure at a fixed voltage bias. It is also confirmed that the amount of photocurrent can be easily adjusted by changing the number of ZnO NW array junctions. The device exhibits clear response to the repeated UV illumination, suggesting that this process can be usefully applied for the facile fabrication of low-cost UV sensor array.
고승환(Ko Seung-Hwan) 서강대학교 철학연구소 2018 철학논집 Vol.54 No.-
기존 연구에서 茶山 丁若鏞의 감정론은 조선 유학의 사단칠정론의 연장선상에서 해석되는 경향이 있다. 하지만 감정에 대한 다산의 접근은 기존의 선배 학자들과는 여러 면에서 다르다. 유형과 무형의 氣와 靈의 세계를 이원적으로 설정하고, 靈明의 대체를 하늘로부터 직접 받는다고 주장한다. 이로부터 영명한 대체에서 발하여 나오는 도심의 순수한 발현과 이에 대한 즉각적인 앎의 가능성이 주어진다. 이러한 특징에 주목하여 필자는 다음과 같은 몇 가지 명제를 주장한다. 첫째, 수양 론에 있어 핵심은 도심에 대한 자각과 보존에 있지, 기질의 욕구를 줄이거나 제거하는 데에 있지 않다. 둘째, 현실적인 어려움에도 불구하고, 윤리적 실천은 행위 주체 내에서 도심을 통해 스스로 가능하며, 이에 비해 감정은 부차적인 요소로 억제의 대상으로 제시된다. 셋째, 도심의 양태인 사단은 인간에게 불안으로 자극되며, 상제에 대한 두려움은 이 불안이라는 심적 상태를 강화하는 요소로 작용한다. 넷째, 다산은 도심을 강화하는 방법으로 제시된 계신과 공구를 구분하고 있으며, 계신은 도심이라는 내면의 양심으로 충분히 가능하다고 보지만, 공구는 上帝라는 초월자없이 상정될 수 없다고 본다. 다섯째, 다산의 윤리 이론에서 樂處, 즉 행복은 지향의 대상이나 미래에나 실현될 이상향(至善)으로 그려지며 현실에서 구현되기 어려운 측면이 있다. Tasan s theory of emotion in previous studies has tended to be interpreted as an extension of the Four-Seven debate of Joseon Confucianism. However, Tasan s approach to emotions(whether moral or not) differs in many respects from his predecessor Confucian. Tasan sets the dual world, Qi(氣, the material) and Ling(靈, the spiritual), and claims that the substance of Spirit is directly received from Heaven. This gives us the possibility of a pure manifestation of Tao mind emerging from the substance of Spirit and immediate awareness of it. With this feature in mind, I assert some propositions: First, the key to self-cultivation in Tasan philosophy is in awareness and preservation of the Tao mind, not in reducing or eliminating desires. Second, in spite of realistic difficulties, ethical practice is only possible through the Tao mind which works as the incentive of the moral disposition, and there is no antecedent feeling with regard to moral behavior. Third, Human mind is stimulated with anxiety from the four modification of the Tao mind, and the recognition of supreme god reinforces the mental state of this anxiety through the reverential fear. Fourth, Tasan distinguishes between Jieshen(戒愼, Humiliation) and Kongju(恐懼, Reverential Fear) presented in the way of strengthening the Tao mind. Tasan sees that Humiliation is possible through the inner conscience of Tao mind, but the reverential fear can not be assumed without existence of the supreme god. Fifth, in Tasan s theory of ethics, happiness(樂處) is provided as an object of intention or an ideal to be realized in the future, not in reality.
고성능 염료감응형 유연 태양전지 구현을 위한 기능성 나노구조체 저온 공정개발
고승환(Seung Hwan Ko) 대한기계학회 2010 대한기계학회 춘추학술대회 Vol.2010 No.11
Functional nanostructured materials are the key to the high efficiency energy generation devices such as solar cell by enhancing the surface area. Solar cells on a polymer substrate can reduce the process cost and broaden the application area to portable electronics and building integrated solar cell. We have developed several novel approaches to fabricate high efficiency dye sensitized solar cell with on a heat sensitive plastic substrate without using any vacuum deposition techniques. The functional nanostructure showed great improvement in solar cell efficiency.
나노물질의 선택적 레이저 소결을 이용한 유연전기소자의 구현
고승환(Seung Hwan Ko),여준엽(Jun Yeob Yeo),홍석준(Sukjun Hong),한승용(SeungYong Han),이진환(JinHwan Lee),노윤수(YoonSoo Rho),서영덕(Young Duk Seo),전진아(JinA Jeon),남구현(Koo Hyun Nam) 대한기계학회 2010 대한기계학회 춘추학술대회 Vol.2010 No.11
The development of electric circuit fabrication on heat and chemically sensitive polymer substrates has attracted significant interest as a pathway to low-cost or large-area electronics. Flexible electronics are the electronics on flexible substrates such as a plastic, fabric or paper, so that they can be folded or attached on any curved surfaces. They are currently recognized as one of the most innovating future technologies especially in the area of portable electronics. The conventional vacuum deposition and photolithographic patterning methods are well developed for inorganic microelectronics. However, flexible polymer substrates are generally chemically incompatible with resists, etchants and developers and high temperature processes used in conventional integrated circuit processing. Additionally, conventional processes are time consuming, very expensive and not environmentally friendly. Therefore, there are strong needs for new materials and a novel processing scheme to realize flexible electronics. This paper introduces current research trends for flexible electronics based on (a) nanoparticles, and (b) novel processing schemes: nanomaterial based direct laser patterning methods to remove any conventional vacuum deposition and photolithography processes. Among the several unique nanomaterial characteristics, dramatic melting temperature depression (Tm, 3㎚ particle~150℃) and strong light absorption can be exploited to reduce the processing temperature and to enhance the resolution. This opens a possibility of developing a cost effective, low temperature, high resolution and environmentally friendly approach in the high performance flexible electronics fabrication area.
나노물질의 선택적 레이저소결을 이용한 유연전기소자 구현 연구현황
고승환(Seung Hwan Ko) 대한기계학회 2011 大韓機械學會論文集B Vol.35 No.5
대부분의 유연전기소자는 플라스틱, 옷감, 종이와 같이 고온에 민감한 물질이기 때문에 열에 민감한 기판 위에 금속을 증착하고 패터닝할 수 있는 저온 공정의 개발이 필요하다. 최근 기존의 광식각과 진공증착 방법을 이용하지 않고 액상으로 금속 나노입자의 박막을 형성하고 선택적 레이저 소결을 이용하여 플라스틱에 열적손상을 최소화하고 고해상도의 금속 패터닝을 방법이 많은 연구가 활발히 진행되고 있다. 본 논문에서는 본 연구실에서 활발히 수행중인 나노물질의 선택적 레이저소결법을 이용하여 유연 디스플레이와 유연태양전지와 같은 유연전기소자의 개발 동향에 대해 알아보고 앞으로의 발전방향에 대해 논의한다. A plastic-compatible low-temperature metal deposition and patterning process is essential for the fabrication of flexible electronics because they are usually built on a heat-sensitive flexible substrate, for example plastic, fabric, paper, or metal foil. There is considerable interest in solution-processible metal nanoparticle ink deposition and patterning by selective laser sintering. It provides flexible electronics fabrication without the use of conventional photolithography or vacuum deposition techniques. We summarize our recent progress on the selective laser sintering of metals and metal oxide nanoparticles on a polymer substrate to realize flexible electronics such as flexible displays and flexible solar cells. Future research directions are also discussed.