• 열처리공학회지
• /
• 제7권4호
• /
• pp.298-306
• /
• 1994

This study was performed to investigation the effect of austempering temperature on the mecanical properties and fracture Characteristic of the ductile cast iron with contains Cu and Mo. The obtained results of this study were as follows; Microstructure of austemped ductile cast iron obtained by austempering were low bainite with some martensite at $250^{\circ}C$, mixture of low and upper bainite at $300^{\circ}C$ and upper bainite at $350^{\circ}C$. With increasing austempering temperature, yield strength, tensile strength and hardness decreased, while the elongation and impact absorption energy increased. With increasing austempering temperature, fracture toughness value increased and mainly controlled by bolume fraction of retained austenite. The volume fraction of retained austenite increased and the fracture surface obtained fibrous and dimple with increasing austempering temperature.

• 대한기계학회:학술대회논문집
• /
• 대한기계학회 2007년도 춘계학술대회A
• /
• pp.756-761
• /
• 2007

This papered is concerned with the crashworthiness characteristics analysis of the non-step bus when it is crashed or roll-over analysis. Computer simulations is implemented using LS-Dyna explicit code which can effectively analysis dynamic response with the lapse of time. We construct a FEM model of the non-step bus under development according to the safety rules used in Europe for composite non-step buses. The crash energy and absorption rate are evaluated to understand crashworthiness characteristic of the composite non-step bus. Body deformation is also examined whether the survival space is secured for passengers.

• 한국가스학회지
• /
• 제24권5호
• /
• pp.29-38
• /
• 2020

산업현장의 대형 연소시스템 내부의 온도 및 농도를 실시간으로 정밀하게 계측하는 일은 그 규모 및 환경 조건으로 인해 사실상 어렵다. 현재 주로 사용되고 있는 열전대를 이용한 온도 계측은 점 측정 방식으로 대형 연소시스템 내부 광역 범위의 온도 분석에 적용하기에는 정밀성과 신뢰성이 낮으며, 접근성에 한계가 있다. 농도 분석 측면에서 대부분의 계측 방법은 샘플링 방식으로 실시간 측정이 어렵고 대표성에 한계가 있다. 이러한 한계점을 극복하기 위한 방법으로, 레이저를 이용한 측정법이 지속적으로 개발되고 있다. 레이저 기반 측정법들은 선 평균 측정 방식으로 대표성과 정밀도가 뛰어나 대형 연소시스템 적용에 유리하다. 본 연구에서는 파장 가변형 레이저 흡수 분광법(Tunable Diode Laser Absorption Spectroscopy, TDLAS)을 통해 연소 시에 발생하는 수증기와 산소를 이용하여 실시간으로 온도 및 농도를 측정하였다. 측정 결과 연소시스템 내부 평균 온도는 1330℃, 평균 산소 농도는 3.3 %로 발전소 데이터와 비교하였을 때 유사한 경향성의 측정값을 얻었다.

• Macromolecular Research
• /
• 제12권3호
• /
• pp.322-324
• /
• 2004

Poly(1-dodecyl-2,5-pyrrylene vinylene) (PDPV) has an extended 1t-conjugated structure and exhibits characteristic spectroscopic features. The PDPV we prepared has an absorption maximum at 510nm and its long absorption tail at ca. 750nm in methylene chloride is due to the long 1t-conjugated system connected to vinyl group. The large red-shift of emission was 625nm upon excitation at 480nm, which suggests the existence of a low emissive state. The emission of PDPV in less-polar solvents decreased markedly relative to that in the more-polar solvents; this observation was ascribed possibly to quenching by a strong vibrational mode of the dodecyl groups of PDPV in less-polar solvents. Furthermore, the emission from the high-energy side had a single decay component (0.1㎱, 49.96%), while that from the low-energy side had two components (0.6㎱, 27.1 %; 2.7㎱, 22.87%). We characterized the redox properties of PDPV by cyclic voltammetry. Every redox peak showed irreversible behavior; the oxidation peaks appeared at 1.7,0.8, and 0.6V and the reduction peak at -0.5V.

• 한국재료학회지
• /
• 제18권10호
• /
• pp.515-520
• /
• 2008

We fabricated 10 nm-$TiO_2$ thin films for DSSC (dye sensitized solar cell) electrode application using ALD (atomic layer deposition) method at the low temperatures of $150^{\circ}\;and\;250^{\circ}$. We characterized the crosssectional microstructure, phase, chemical binding energy, and absorption of the $TiO_2$ using TEM, HRXRD, XPS, and UV-VIS-NIR, respectively. TEM analysis showed a 10 nm-thick flat and uniform $TiO_2$ thin film regardless of the deposition temperatures. Through XPS analysis, it was found that the stoichiometric $TiO_2$ phase was formed and confirmed by measuring main characteristic peaks of Ti $2p^1$, Ti $2p^3$, and O 1s indicating the binding energy status. Through UV-VIS-NIR analysis, ALD-$TiO_2$ thin films were found to have a band gap of 3.4 eV resulting in the absorption edges at 360 nm, while the conventional $TiO_2$ films had a band gap of 3.0 eV (rutile)${\sim}$3.2 eV (anatase) with the absorption edges at 380 nm and 410 nm. Our results implied that the newly proposed nano-thick $TiO_2$ film using an ALD process at $150^{\circ}$ had almost the same properties as thsose of film at $250^{\circ}$. Therefore, we confirmed that the ALD-processed $TiO_2$ thin film with nano-thickness formed at low temperatures might be suitable for the electrode process of flexible devices.

• 한국수소및신에너지학회논문집
• /
• 제7권1호
• /
• pp.63-69
• /
• 1996

Effect of nickel powder to added to the hydrogen absorbing alloy electrode of $MmNi_{4.5}-xCoxMn_{0.3}Al_{0.2}$ system alloy was investigated. The addition of nickel powder was effective for the improvement of discharging characteristic. It was found that the discharge capacity was 310mAhig when the alloy negative electrode was mixed $MmNi_{3.75}CO_{0.75}Mn_{0.3}Al_{0.2}$ and nickel powder with a mix of one to three. Still another, we have investigated thermodynamic stability of hydrogen in the alloy negative electrode. As a result, enthalpy of hydrogen and hydrogen equilibrium pressure in the alloy negative electrode were a suitable value to easy hydrogen absorption-desorption.

• Structural Engineering and Mechanics
• /
• 제60권5호
• /
• pp.829-849
• /
• 2016

In this paper, experimental as well as numerical analysis of Glass Fiber Reinforced Polymer (GFRP) laminated composite has been presented under ballistic impact with varying projectile nose shapes (conical, ogival and spherical) and incidence velocities. The experimental impact tests on GFRP composite plate reinforced with woven glass fiber ($0^{\circ}/90^{\circ}$)s are performed by using pneumatic gun. A three dimensional finite element model is developed in AUTODYN hydro code to validate the experimental results and to study the ballistic perforation characteristic of the target with different parametric variations. The influence of projectile nose shapes, plate thickness and incidence velocity on the variation of residual velocity, ballistic limit, contact force-time histories, energy absorption, damage pattern and damage area in the composite target have been studied. The material characterization of GFRP composite is carried out as required for the progressive damage analysis of composite. The numerical results from the present FE model in terms of residual velocity, absorbed energy, damage pattern and damage area are having close agreement with the results from the experimental impact tests.

• 한국산학기술학회:학술대회논문집
• /
• 한국산학기술학회 2011년도 춘계학술논문집 1부
• /
• pp.317-319
• /
• 2011

본 논문에서는 최근에 주목 받고 있는 물질인 이온성액체를 실험실 규모로 제조하여 회분식 기-액 흡수평형(VLE)장치를 이용하여 압력에 따른 이산화탄소 용해도 및 초기흡수속도를 상용 이온성액체인 $PF_6$와 비교분석 하였다. 반응온도 $40^{\circ}C$조건에서 운전하였으며, 이산화탄소 압력 0~40기압 범위에서 수행되었다. 실험결과 methyl기가 붙은 합성 이온성액체의 경우 초기흡수속도면에서 상용 이온성액체인 $PF_6$보다는 다소 낮은 수준이다.

• 항공우주시스템공학회지
• /
• 제4권3호
• /
• pp.1-5
• /
• 2010

Understanding the crushing behaviour of aluminum honeycombs under dynamic loading is useful for crash simulations of vehicles and for design of impacting energy absorbers. In the study of honeycomb crushing under quasi-static, dynamic loading, the most important parameter is crush strength. Crush strength is indicated to energy absorption characteristic of aluminum honeycomb. In this study, Using Finite Element Analysis carried out crush strength of hexagonal aluminum honeycomb then the results was compared with Quasi-static test. Consequently, Crush strength is different in quasi-static loading and dynamic loading about 16%.

• 한국감성과학회:학술대회논문집
• /
• 한국감성과학회 2000년도 춘계 학술대회 및 국제 감성공학 심포지움 논문집 Proceeding of the 2000 Spring Conference of KOSES and International Sensibility Ergonomics Symposium
• /
• pp.35-38
• /
• 2000

Conventional atom model must be criticized on the following four points.(1) natural motions between positive and negative entities are not circular motions but linear going and returning ones, for examples sexual motion, tidal motion, day and night etc.(2) Potential energy generation was neglected when electron changes its orbit from outer one to inner one. The hv is the kinetic energy of the photo-electron. The total energy difference between orbits comprises kinetic and potential energies. (3) The structure of the space must be taken into consideration because the properties of the electron do not changed during the transition from outer orbit to inner one even though it produces photon. (4) Total energy conservation law applies to the energy flow between mind and matter because we daily experiences a interconnection between mind and body.New atomic model 9the crystallizing $\pi$-bonding) was proposed in the journal of material processing technology since 1997 for the explanation of the mechanical behaviors in terms of physics. $\prod$-ray physics proved that the electrons can come out from in the nucleus and modern chemistry corresponds to the $\pi$-bonding by the nuclear electrons. The $\pi$-bonding structure of the protons outside the nucleus is that electrons move between protons of the different atoms. The perception step and the characteristic frequency in signal transduction is due to the accumulation of the $\pi$-rays outside of the proton before their absorption to the nucleus.