Servo 구동 장력 조절 장치 최적화 설계에 관한 연구

이상화,정혜천,이혁진,이재원,전두환,Lee, Sang-Hwa,Jeong, Hye-Cheun,Lee, Huck-Jin,Lee, Jeh-Won,Chun, Du-Hwan 한국섬유공학회 2008 한국섬유공학회지 Vol.45 No.3

Tension control of fiber manufacturing process system is usually achieved by using loadcell and powder clutch, which require additional mounting space, reduce the reliability in harsh environments and increase the cost of the system. The physical properties of textile fabrics are very sensitive to several factors(temperature, humidity, radius change of warp beam etc.)which result in tension change. In this paper, the optimal tension control of servo motor driver system using PI control algorithm is presented. The proposed tension algorithm is robust to disturbance and tension variation. First the modeling and dynamic behaviors of the tension system is described. Then validity and usefulness of the proposed algorithm and mechanical system are thoroughly verified through numerical simulation and actual conditions.

단일 균열암반에서 핵종/콜로이드 복합이동에 대한 수치모델 개발

이상화,김정우,정종태,Lee, Sanghwa,Kim, Jung-Woo,Jeong, Jongtae 한국방사성폐기물학회 2012 방사성폐기물학회지 Vol.10 No.4

본 연구에서는 콜로이드와 핵종의 복합이동에 관한 수치모델을 개발하였다. 콜로이드와 핵종의 반응-이동 지배방정식을 풀기 위하여 Operator Splitting Method 중 Strang의 분리 SNI 방식을 수치해석 방법으로 채택하였고 이는 MATLAB을 이용하여 코드화 되었다. 개발된 수치모델은 용질의 이동 및 분산만을 고려한 해석해를 통한 검증과정에서 피어슨 상관계수의 제곱값($r^2$)이 0.99 이상으로 나타나 모델의 정확성이 입증되었다. In this study, numerical model for transport of radionuclide and colloid was developed. In order to solve reaction-migration governing equation for colloid and radionuclide, Strang-splitting Sequential Non-Iterative (SNI), which is one of Operator Splitting Method, was used for numerical method and this was coded by MATLAB. From the verification by comparing the simulation results with analytical solution considering only solute transport and rock diffusion, the Pearson's correlation coefficient was greater than 0.99 which demonstrates the accuracy of the model.

포화탄화수소의 탄수소고리화 반응에 관한 촉매특성 연구

이상화,이호인 ( Sang Hwa Lee,Ho In Lee ) 한국공업화학회 1993 공업화학 Vol.4 No.3

담지된 백금촉매에 주석의 첨가는 포화탄화수소의 탈수소고리화 반응에 대한 촉매의 활성 및 안정도의 현저한 증가를 가져왔다. n-octane의 탈수소고리화 반응에서 0.75wt%의 Pt에 대해 주석의 몰비가 약 4일 때 가장 높은 촉매적 활성을 나타냈다. 또한 K의 첨가도 n-hexane의 탈수소고리화 반응에 대해 주석과 비슷한 효과를 나타내었다. n-octane의 전환반응의 경우에는, K의 첨가 효과가 적게 나타났다. The addition of Sn to Pt/γ-Al_2O_3 catalyst greatly enhanced the activity and decreased the deactivation rate for the dehydrocyclization of paraffins. For the dehydrocyclization of n-octane, there appeared to be an optimal ratio of Pt:Sn= 1 :4 for 0.75 wt% Pt/γ-Al_2O_3 catalyst. The addition of K to Pt/γ-Al_2O_3 also produced a similar effect on the dehydrocyclization of n-hexane. In the case of n-octane, the addition of K led to a less selective catalyst.

A Study on the Catalytic Property of Pt/γ-Al₂O₃ on the Dehydrocyclization of Paraffins

이상화,이호인,Lee, Santg-Hwa,Lee, Ho-In The Korean Society of Industrial and Engineering C 1993 공업화학 Vol.4 No.3

The addition of Sn to Pt/${\gamma}$-$A1_2O_3$ catalyst greatly enhanced the activity and decreased the deactivation rate for the dehydrocyclization of paraffins. For the dehydrocyclization of n-octane, there appeared to be an optimal ratio of Pt:Sn=1:4 for 0.75 wt% Pt/${\gamma}$-$A1_2O_3$ catalyst. The addition of K to Pt/${\gamma}$-$A1_2O_3$ also produced a similar effect on the dehydrocyclization of n-hexane. In the case of n-octane, the addition of K led to a less selective catalyst. 담지된 백금촉매에 주석의 첨가는 포화탄화수소의 탈수소고리화 반응에 대한 촉매의 활성 및 안정도의 현저한 증가를 가져왔다. n-octane의 탈수소고리화 반응에서 0.75wt%의 Pt에 대해 주석의 몰비가 약 4일 때 가장 높은 촉매적 활성을 나타냈다. 또한 K의 첨가도 n-hexane의 탈수소고리화 반응에 대해 주석과 비슷한 효과를 나타내었다. n-octane의 전환반응의 경우에는, K의 첨가 효과가 적게 나타났다.

국제보험시장에서 화재보험의 주요당면문제

이상화,Lee, Sang-Hwa 한국화재보험협회 1976 防災와 保險 Vol.6 No.-

유비쿼터스 주거공간의 기능적 위계성 분석에 관한 연구

이상화,최동식,Lee, Sang-Hwa,Choi, Dong-Sik 한국주거학회 2007 한국주거학회 논문집 Vol.18 No.3

This study is aimed at interpreting into changes and characters of function applied into quantative analysis in ubiquitous house. Digital technology being introduced into architectural fields, It applied expansively from design and construction to user's convenience. The application of digital technology is presented to various change like effectiveness and exactness in design and function of space, which is overlayed digital space to physical space beyond the extent of receiving human needs in physical space. In ubiquitous house, digital technologies are supplied to function coordinated with life, appreciating into positional informations of human and materials, spatial informations. Ubiquitous house is comparably effective into funtional expansion, user's convenience, safty, which, for the future, is going to using on housing of high performance encouraging the application of advanced technology. Therefore this study is classified into human behaviors, functions, performances and characters of digital system in ubiquitous house, which being established into the relation of elements, is interpreted numerically into functional changes and charats being applied to ARM.

질화갈륨 나노 막대 형성을 위한 핵화층의 성장 온도에 따른 물성 연구

이상화,최혁민,김진교,Lee Sang-Hwa,Choe Hyeok-Min,Kim Chin-Kyo 한국진공학회 2006 Applied Science and Convergence Technology Vol.15 No.2

수소화물기상증착법을 이용하여 질화갈륨 핵화층을 성장시켰고, 성장 온도에 따라 상이한 구조적 특성을 갖는 핵화층이 질화갈륨 나노막대의 형성에 어떤 영향을 주는지 방사광 x-선 산란과 원자힘 현미경을 이용하여 연구하였다. 서로 다른 온도에서 성장시킨 질화갈륨 핵화층들의 (002) 브래그 봉우리에 대한 록킹 곡선(rocking curve)을 측정한 결과, 반폭치가 작은 주 봉우리와 반폭치가 넓은 작은 봉우리의 합으로 표현됨을 관측하였다. 이러한 현상은 핵화층의 표면 형상과 연관되어져서 설명될 수 있음을 정성적으로 보였고, AFM 결과와 비교해 볼 때 안정적인 나노막대 성장을 위해서는 핵화층이 저온에서 성장되어야 함을 확인하였다. GaN nucleation layers were grown by hydride vapor phase epitaxy (HVPE) and the effect of growth temperature on the structural properties of GaN nucleation layers for nanorods was investigated by synchrotron x-ray scattering and Atomic Force Microscopy (AFM). For the samples grown at different temperatures, two-component rocking profiles of (002) GaN Bragg peaks for the GaN nucleation layers were observed with one very sharp and the other broad. It was shown that the two-component rocking profile could be qualitatively explained by surface morphology, which was in good agreement with AFM result, from which we could conclude that relatively low temperature is favorable for GaN nanorods formation.

비정형과 정형 주거공간의 시지각적 특성에 관한 연구

이상화,Lee, Sang-Hwa 한국주거학회 2007 한국주거학회 논문집 Vol.18 No.3

This study is aimed at understanding objectively on the visual perception of atypical space and form in contemporary architecture. It is accomplished to compose the various form and the atypical space in contemporary architecture, which by means of applying digital technology to architecture is able to materialize complicated form and space. Therefore this the sis is needed to understand user's senses and affects in atypical space and form. Atypical space is able to interpret geometrically and analyze quantitatively into visual perception. This analysis is applied to Isovist used as quantitative analysis recently, and physical analysis of space used as quantitative analysis defined to vertical elements, which is analysed comparatively to visual perception in observer's point and characteristics in spatial elements. Examples are selected to four examples represented to typical and atypical space in contemporary houses. As examples are analysed to visual perception of spatial character, this study is intended to understand to spatial character in aspects of spatial composition and observer's visual perception. In results of perceptive analysis on four spatial examples, Atypical spaces are composed of changeable spatiality, which are composed changeably of the relational method with adjacent spaces. Also, typical spaces are composed monotonously of spatiality and relational method on control of the length in boundary plane and openness.

정보의 집중관리와 교환체제 확립이 경제적

이상화,Lee, Sang-Hwa 한국화재보험협회 1987 防災와 保險 Vol.35 No.-

Analysis of the Wettability of Partially Fluorinated Polymers Reveals the Surprisingly Strong Acid-Base Character of Poly(vinylidene Fluoride)

이상화,Joon-Seo Park,T. Randall Lee 대한화학회 2011 Bulletin of the Korean Chemical Society Vol.32 No.1

The wettabilities of the partially fluorinated polymers (ethylene-tetrafluoroethylene copolymer (ETFE), ethylenechlorotrifluoroethylene copolymer (ECTFE), and poly(vinylidene fluoride) (PVDF)) were investigated by contact angle measurements. Zisman plots for ETFE and ECTFE exhibited linear relationships, while the Zisman plot for PVDF showed a slight curvature, which was interpreted to indicate strong non-dispersive interactions between the surface and the contacting liquids. The Lifshitz-van der Waals forces of the fluoropolymers were estimated to increase in the order of ETFE < PVDF << ECTFE. An evaluation of the polar or "acid-base" interaction energies showed that PVDF, which possesses the most acidic hydrogens among the examined fluoropolymers, has the strongest acid-base interactions.