• 한국생산제조학회지
• /
• 제19권2호
• /
• pp.235-240
• /
• 2010

The recent trend of vehicle design aims at crash safety and environmentally-friendly aspect. For the crash safety aspect, energy absorbing members should be absorbed with collision energy sufficiently. But vehicle structure must be light weight for the environmentally-friendly aspect, in order to improve fuel efficiency and to reduce tail gas emission. Therefore, the light weight of vehicle must be achieved in a status of securing safety of crash. An aluminum or CFRP (Carbon Fiber Reinforced Plastics) is representative one among the light-weight materials. In this study, impact collapse behavior of circular hybrid thin-walled member is evaluated. The hybrid members are manufactured by wrapping CFRP prepreg sheets outside the aluminum circular members in the autoclave. Because the CFRP is an anisotropic material whose mechanical properties change with its stacking condition, special attention is given to the effects of the stacking condition on the collapse behavior evaluation of the hybrid thin-walled member. Collapse mode and energy absorption capability of the hybrid thin-walled member are analyzed with change of the fiber orientation angle and interface number.

• Journal of Advanced Marine Engineering and Technology
• /
• 제30권5호
• /
• pp.636-644
• /
• 2006

Recently, there were some successful examples that the laser welding was introduced into production line. However, the spread of laser welding is not sufficient in many industries. There are several reasons why it is difficult to penetrate the laser welding into production lines. Because it is different from reflection, absorption and permeation of laser beam according to material and surface condition. Moreover, there are significant problems in processing such as absorption and scattering of beam by the induced plasma or plume. Therefore, understanding of mechanism on formation of weld defect in laser welding of the laminated core for motor is very important. In this paper, it was analyzed in terms of materials which was source of defect in laser welding and conventional arc welding. As a results of analysis, insulation coating film of the laminated core was judged to main factor of weld defect. it could be well aware as tracing carbon volume, and it was deduced that weld defect by insulation coating film was caused by difference of mechanism between the two heat sources.

• 한국의상디자인학회지
• /
• 제17권2호
• /
• pp.45-61
• /
• 2015

In order to analysis on color difference of natural dyes, I have dyed Hanji, cotton, silk fabric and exposed them to carbon arc light. The results of experiment have been analysed by wavelength of maximum absorption, amounts of dye uptake, color difference, Hunter's value and Munsell's value. Gardenia Jasminoides is monogenetic dye, but it gained darker color by pre-mordanting method used Al mordant agent and greenish yellow color by Fe mordant agent. whereas Curcuma, an Amur cork, and bud of pagoda tree are shown as greenish yellow color, and A barberry root, Betel nut, and Rhubarb are shown as reddish yellow color. these gained khaki colored dyed fabric by Fe mordanting. In addition, Sappan wood showed great result in pre-mordanting. Especially, it gained dark red color by Al pre-mordanting. The pink color was shown by post-mordanting. and Logwood showed great dyeing result in Hanji and cotton better than silk. Specially pre-mordanting was effective. Hanji and cotton showed greenish blue color by Al pre-mordanting, and silk showed brown color.

• 대한의용생체공학회:의공학회지
• /
• 제34권2호
• /
• pp.91-96
• /
• 2013

In this study, we developed an integrated optical coherence tomography - photoacoustic microscopy (OCT-PAM) system to simultaneously provide optical absorption and scattering information. Two different laser sources, such as a pulsed laser for PAM and a superluminescent diode for OCT, were employed to implement the integrated OCT-PAM system. The performance of the OCT-PAM system was measured by imaging carbon fibers. We then imaged black and white hairs to demonstrate the simultaneous OCT-PAM imaging capabilities. As a result, OCT can produce 3-D images of both black and white hairs, whereas PAM is only able to image the black hair due to strong optical absorption of black hair.

• 한국생산제조학회지
• /
• 제21권6호
• /
• pp.865-870
• /
• 2012

CFRP of the advanced composite materials as structure materials for vehicles has a widely application in lightweight structural materials of air planes, ships and automobiles because of high strength and stiffness compared with conventional materials. This study is to investigate the energy absorption characteristics and collapse mode of CFRP single and double hat shaped structural member under the axial static collapse test. The CFRP single and double hat shaped structural members stacked at different angles (${\pm}15^{\circ}$, ${\pm}45^{\circ}$, ${\pm}90^{\circ}$, $90^{\circ}/0^{\circ}$ and $0^{\circ}/90^{\circ}$ where the direction on $0^{\circ}$ coincides with the axis of the member). The axial static collapse tests were carried out for each member. Collapse mode and energy absorption characteristics of the each member were analyzed.

• 대한화학회지
• /
• 제32권6호
• /
• pp.513-519
• /
• 1988

헥사메틸벤젠과 1,3,5-트리니트로벤젠과의 사이에 전하이동착물의 안정도에 미치는 압력과 온도의 영향을 사염화탄소용액내에서 분광광도법으로 연구하였다. 압력은 1, 200, 500, 1000, 1400 bar. 온도는 25, 40, $50^{\circ}C$사이에서 측정하였다. 착물의 평형상수는 압력 및 온도 증가와 더불어 증가 또는 감소하고 흡수계수는 대체로 증가함을 알았다. 이들 각 평형상수로부터 착물형성에 따른 부피, 엔탈피, 자유에너지 및 엔트로피 변화량을 구하였다. 도한 압력 증가에 의한 red-shift, 온도 증가에 의한 blue-shift 현상 및 압력 변화에 의한 진동자세기의 관계를 열역학함수와 관계지어 설명하였다.

• Bulletin of the Korean Chemical Society
• /
• 제31권4호
• /
• pp.989-998
• /
• 2010

The titled dye of DBPI gives amplified spontaneous emission (ASE) with maximum at 580 nm upon pumping by nitrogen laser (${\lambda}_{ex}\;=\;337.1\;nm$). The ground state absorption cross section (${\sigma}_A$) and emission cross section (${\sigma}_E$) as well as effective emission cross section(${\sigma}^*_E$) have been determined. The electronic absorption spectra of DBPI were measured in ethanol and tetrahydrofuran at room and low temperature. DBPI displays molecular aggregation in water. The photochemical reactivity of DBPI was also studied in carbon tetrachloride upon irradiation with 525 nm light. The electrochemical investigation of DBPI dye has been carried out using cyclic voltammetry and convolution deconvolution voltammetry combined with digital simulation technique at a platinum electrode in 0.1 mol/L tetrabutyl ammonium perchlorate (TBAP) in two different solvents acetonitrile ($CH_3CN$) and dimethylformamide (DMF). The species were reduced via consumption of two sequential electrons to form radical anion and dianion (EE mechanism). In switching the potential to positive direction, the compound was oxidized by loss of two sequential electrons, which were followed by a fast dimerization and/or aggregation process i.e $EC_{dim1}EC_{dim2}$ mechanism. The electrode reaction pathway and the chemical and electrochemical parameters of the investigated compound were determined using cyclic and convolutive voltammetry. The extracted electrochemical parameters were verified and confirmed via digital simulation method.

• 대한화장품학회지
• /
• 제28권1호
• /
• pp.214-224
• /
• 2002

High concentrated $TiO_2$ nano colloids were synthesized by sol-gel method. Reactions were performed in $TiCl_4$/HCl/$H_2O$ aqueous solution and the conditions of particles such as shape, size and aggregation, etc. were controlled by polymerization and adsorption of acrylamide in surface of $TiO_2$ nano particles. And also, aminopropyltriethoxysilane was added instead of acrylamide and compared each other. The prepared colloids were well dispersed and showed the strong absorption peaks at 350nm-370nm which is blue shifted to 20-30nm, compared to macro particles. The obtained techniques from $TiO_2$ nato colloids synthesis were utilized in coating on boron nitride powders which are nonpolar and isoelectronic materials of carbon. Their surface morphology, structure, thermal stability and U. V absorption chracteristics were examined by SEM(Scanning Electron Microscopy), XRD(X-ray diffraction), TG/DTA(Thermogravimetric and Differential Thermal Analysis), UV-VIS(Ultraviolet-Visible Spectroscopy).

• Carbon letters
• /
• 제10권3호
• /
• pp.177-180
• /
• 2009

The importance of nanopore structures of carbons is shown in terms of interaction potential for various molecules including supercritical gases such as $H_2$ and $CH_4$. The key factors for adsorption of supercritical $H_2$ and $CH_4$ are shown for single wall carbon nanohorn, single wall carbon nanotube, and double wall carbon nanotube. The cluster formation of molecules is a key process for water adsorption on hydrophobic carbon nanopores. The X-ray absorption spectroscopic examination elucidates an explicit dehydration structure of ions confined in carbon nanopores.

• 한국산학기술학회논문지
• /
• 제21권10호
• /
• pp.361-371
• /
• 2020

2020년 일몰제가 시행되면서 장기미집행공원 개발에 대한 우려가 제기되고 있다. 본 연구의 목적은 장기미집행공원이 개발됨에 따라 소실되는 탄소량과 경제적 가치를 평가하여 장기미집행공원 개발에 따른 영향 최소화 방안 도출에 근거를 제공하고자 한다. 본 연구에서는 FSDAF 시공간 영상융합기법과 CASA-NPP 모형을 활용하여 서울시 내 장기미집행공원의 연평균 NPP를 산정하고, 이를 바탕으로 5개의 개발 시나리오에 따라 소실되는 탄소량과 경제적 손실을 평가하였다. 서울시 내 개발제한구역을 제외한 장기미집행공원의 총 NPP 값은 4,892.18 t C로 나타났으며, 개발 시나리오 1에서는 4,892.18 t C, 개발 시나리오 2에서는 2,548.55 t C, 개발 시나리오 3에서는 238.94 t C, 개발 시나리오 4에서는 848.38 t C, 개발되는 시나리오 5에서는 1,596.00 t C의 탄소가 소실될 것으로 나타났으며, 각각 5개의 개발 시나리오에 따른 탄소의 사회적 비용을 계산하면 약 11억 8천만원, 6억 1천만원, 5천 8백만원, 2억 5백만원, 3억 8천 5백만원이며 개발로 인해 해당금액의 경제적 손실이 발생할 것으로 나타났다. 본 연구의 결과는 5개의 개발 시나리오를 바탕으로 장기미집행공원의 탄소 손실량과 경제적 손실을 평가하였다는데 의의가 있으며, 일몰제 이후 개발가능성이 높은 장기미집행공원 내 산림생태기능에 대한 영향 최소화 방안 마련, 개발 대안의 기초자료로 활용되기를 기대한다.