• 접착 및 계면
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• 제5권3호
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• pp.10-17
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• 2004

본 연구에서는 레이온직물에 대하여 승온속도, 안정화온도, 분위기가스, 화학적 표면처리 등 여러가지 조건에서 안정화공정을 행한 후, 직물의 열수축과 열안정성, 그리고 미세구조에 미치는 공정 조건의 영향을 조사하였다. 레이온직물의 열수축과 중량변화에 인산처리 유무와 승온속도가 가장 중요한 영향을 미쳤다. 특히, 인산처리를 한 경우가 하지 않은 경우보다 레이온직물의 두께변화는 약 80%, 길이변화는 약 20%, 그리고 중량변화는 약 26%가 줄어드는 열수축 억제 효과를 보여주었다. 안정화 된 레이온직물의 열안정성에는 안정화온도와 인산처리 그리고 분위기가스와 승온속도 등 주어진 안정화공정 조건 모두가 영향을 주었다. 또한 안정화섬유의 표면 상태 및 섬유직경 변화도 공정 전에 행한 인산처리의 유무에 의존하였다.

• 소성∙가공
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• 제21권4호
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• pp.221-227
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• 2012

The automotive and electronic industries have seriously considered the use of magnesium alloys because of their excellent properties such as strength to weight ratio, EMI shielding capability, etc. However, it is difficult to form magnesium alloys at room temperature because of the mechanical deformation related to twinning. Hence, magnesium alloys are normally formed at elevated temperatures. In this study, a temperature dependent constitutive model, the C-H/V model, for the magnesium alloy AZ31B sheet is proposed. A hardening law based on nonlinear kinematic and H/V(Hollomon/Voce) hardening model is used to properly characterize the Bauschinger effect and the stabilization of the flow stress. Material parameters were determined from a series of uni-axial cyclic experiments(C-T-C) with the temperature ranging between 150 and $250^{\circ}C$. The developed models are fit to experimental data and a comparison is made.

• Carbon letters
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• 제12권4호
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• pp.229-235
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• 2011

Isotactic polyacrylonitrile (PAN) with triad isotacticity of 0.53, which was determined by $^{13}C$ NMR, using dialkylmagnesium as an initiator, was successfully synthesized. Isothermal treatment of iso-PAN was conducted in air at 200, 220, 250 and $280^{\circ}C$. Structural evolutions and chemical changes were studied with Fourier transformation infrared and wide-angle X-ray diffraction during stabilization. A new parameter $CNF={I_{2240cm}}^{-1}/ ({I_{1595cm}}^{-1}+f^*{I_{1595cm}}^{-1})$ was defined to evaluate residual nitrile groups. Crystallinity and crystal size were calculated with X-ray diffraction dates. The results indicated that the nitrile groups had partly converted into a ladder structure as stabilization proceeded. The rate of reaction increased with treatment temperature; crystallinity and crystal size decreased proportionally to pyrolysis temperature. The iso-conversional method coupled with the Kissinger and Flynn-Wall-Ozawa methods were used to determine kinetic parameters via differential scanning calorimetry analysis with different heating rates. The active energy of the reaction was 171.1 and 169.1 kJ/mol, calculated with the two methods respectively and implied the sensitivity of the reaction with temperature.

• Elastomers and Composites
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• 제22권2호
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• pp.109-120
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• 1987

In this study, as one of the developing ways of the functional elastomer, improvement of the functionality of CB-BR was attemped through stabilization. At first the stabilization effect of CB-BR and the concentration dependancy in CB-BR were determined. Then, triazine thiol derivative(BPTT) was synthesized by reacting p-aminodiphenylamine with cyanuric chloride. Further the functional mechanism and the effects of the antioxidants were investigated using BPTT together with other various antioxidants in liquid and solid states. The results obtained are as follows: 1) The aging of CB-BR depended on the concentration and temperature. Thus, at a low temperature of $50^{\circ}C$, the aging proceeded with gel formation; at high temperature above $100^{\circ}C$ and in above 4wt% concentration, the aging occured by the formation of gel. And in concentrations below that, the aging proceeds with a decomposition caused by oxygen attacked to elastomer molecules. 2) The effect of antioxidation of CB-BR in the liquid state was at it's best when the MBIZ and BPTT were used at $110^{\circ}C$, 4hrs after the oxidation. 3) The effect of antioxidation of CB-BR in the solid state was the best choice the simultaneous use of NDBC and BPTT at $50^{\circ}C$, 30days after the oxidation.

• 항공우주시스템공학회지
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• 제7권3호
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• pp.26-32
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• 2013

Passive attitude stabilization method has been widely usde for attitude determination and control of cube satellite due to its advantage of system simplicity. The permanent magnet installed on the cube satellite passively controls the attitude of the satellite such that the satellite is aligned with the earth magnetic field. In this paper, on-orbit thermal behavior of the cube satellite with the permanent magnet attitude stabilization method has been investigated through on-orbit thermal analysis. THe orbit profile obtained from the aforementioned attitude control method has been reflected in the analysis. The analysis results indicate that the thermal design proposed in this study is effective for satisfying the temperature requirements of the commericial mission equipments.

• 한국통신학회논문지
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• 제10권4호
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• pp.168-174
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• 1985

半導體 레이저의 出力 및 波長은 溫度에 대단히 敏感하다. 특히 헤테로다인光通信 씨스템이다. 光學用積密 度量衡器, 高分解能 스텍트로스코프 等測量 및 通信에서 發光源으로 使用하기 爲해서는 適當한 安定化 技術이 要求된다. 이 때 溫度의 安定은 絶對的이다 .따라서 本 硏究에서는 桓溫器의 溫度를 -27$-50^{\circ}$에서 +73$^{\circ}C$까지 임의 設定이 可能하게 하였으며 溫度 安定은 ${\pm}2m{\circ}K$보다 좋은 結果를 얻었다.

• 한국공작기계학회:학술대회논문집
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• 한국공작기계학회 2003년도 춘계학술대회 논문집
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• pp.265-271
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• 2003

This study is for the stable optical source in order to get the precision measurement, which contributes to help the laser frequency and the output to be settled. The laser optical frequency is changed by the length of resonance cavity. The length variation of the laser resonance amplitude is affected by the thermal expansion of that system. So, we try not only to adjust the temperature of the laser tube using the heater for fine length of resonance cavity, but also to maintain the fixed temperature of the resonance cavity for outputting the safe laser optical frequency. Therefore, we must take materials with the thermal expansion of the supporting system, which is closer to it of the laser resonance cavity. Using the materials, we can promote to stabilize the temperature of it. In advance, we also plan to get the settlement of the laser frequency and the output in the long km, optimizing and stabilizing the system.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2019년도 추계 학술논문 발표대회
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• pp.73-74
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• 2019

In order to examine the chemical stabilization through DCG curing of cement paste exposed to high temperature environment, we produced a sample of 40% W/C cement paste and heated it for 180 minutes under the heating temperature of $800^{\circ}C$. The DCG curing time was 6, Three time conditions were divided into 12 and 18 hours. As a result of XRD analysis, Calcite ($CaCO_3$) was found in Theta 29.4, 40, and 46.5o. As the curing time increased, the peak of Calcite also increased, which is due to the increased reaction time with DCG. Therefore, Calcite produced through DCG curing seems to have stabilized chemically by filling the pores generated by heating.

• 한국연소학회지
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• 제18권3호
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• pp.24-30
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• 2013

Flame stabilization characteristics of premixed flames in an annular coaxial 5-tubes burner (AC5TB) were investigated experimentally. The AC5TB was made of five quartz tubes, and the flame stabilization conditions in that burner were investigated with the variation of equivalence ratio and the flow velocities. Flame behaviors inside of narrow annular tubes could be observed directly. Overall flame stabilization conditions were similar to that of the previous study, while the flame behaviors and structures were different mainly due to the controlled uniform distribution of the velocities in channels. Flame flashback conditions were thought to be governed by the competition between heat release rate, heat loss and heat recirculation in each channel. Stationary flames at a fixed location were compared in its velocity distribution and burned gas temperature across the channel. This AC5TB can be a basic configuration for the development of flame stabilization model of porous media combustors, and it will help understand about the real behavior of flames in meso-scale combustion spaces.

• 한국동물학회:학술대회논문집
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• 한국동물학회 1994년도 한국생물과학협회 학술발표대회
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• pp.200.1-200
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• 1994

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