• Applied Biological Chemistry
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• v.30 no.4
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• pp.357-363
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• 1987

The transition temperature of respiratory activity of mitochondria isolated from panicles of rice plant was measured with 41 varieties bred in Korea, which had been agronomically classified into five groups based on their relative cold-tolerance; S (strong cold-tolerance), S-M (moderate to strong cold-tolerance), M (moderate cold-tolerance), M-W (moderate to weak cold-tolerance) and W (weak cold-tolerance). The temperature was found to be $11.5{\sim}13.5^{\circ}C$ for group S, $13.5{\sim}16^{\circ}C$ for group S-M, $16{\sim}17^{\circ}C$ for group M, $17{\sim}18^{\circ}C$ for group M-W, and ${\geq}18^{\circ}C$ for group W respectively with a few exceptions of minor deviation, demonstrating a close correlation between the transition temperature and the chilling susceptivity of a variety. This observation supports the suggestion that the transition temperature of respiratory activity of panicles be adopted as a reliable index for grading a rice variety as to its overall cold tolerance. Also studied is on the methodology for measurement of the transition temperature in the aspect of analytical biochemistry. In addition to the usual polarographic method, a spectrophotometric method which is based on the enzymatic assay of membrane-bound cytochrome C oxidase was examined. This enzyme was found previousely and confirmed again in the present work to be a key factor governing the respiratory trantion at least in plant mitochondria. The optical method was turned out to be very successful, although it was a little more complicate and time-consuming than the electrochemical method.

• Journal of the Korean Ceramic Society
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• v.36 no.3
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• pp.231-236
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• 1999

냉각속도가 재열처리가 AFD 방법에 의해 제작된 76SiO2-14B2O3-6Na2O-4Al2O3 유리박막의 광학적 특성에 미치는 영향을 조사하였다. 유리박막의 열팽창계수는 30$0^{\circ}C$부터 전이온도 사이에서 약 5$\times$10-6/$^{\circ}C$이었으며, 전이온도는 62$0^{\circ}C$였다. 유리박막을 전이온도 이하에서 열처리할 경우 열처리 시간이 증가함에 따라 굴절률은 증가하였으며, 열처리 온도가 증가함에 따라 굴절률의 증가속도는 더 컸다. 열처리온도에 따른 유리박막의 복굴절(TE-TM)감소는 굴절률이 가장 크게 증가하는 온도인 $600^{\circ}C$에서 가장 효과적이다. 한편, 냉각속도가 증가함에 따라 유리박막의 두께는 증가하였으며, 굴절류른 감소하였다.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 1994.04a
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• pp.5-8
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• 1994

고분자 물질은 저분자량의 유기 단량체들이 화학 공유 결합으로 연속적으로 연결된 거대 분자 구조를 갖는다. 고분자 사슬로 연결된 단량체들은 힘의 장 의 지배하에 열에너지에 따라 지속적으로 운동을 한다. 이와같은 단량체들의 운동은 국부적으로 제한되나 온도가 증가되어 유리 전이온도 이상이 되면 분자전체에 상당하는 운동으로 발전하게 된다. 이때 소음 및 진동 에너지는 효과적으로 흡수되어 열에너지로 발산된다. 본고에서는 유리 전이온도에서의 고분자 재료의 특성가 실제 소음 및 진도제어시 고려해야할 고분자 재료의 특성에 관해 알아본다.

• Applied Chemistry for Engineering
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• v.5 no.6
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• pp.1030-1035
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• 1994

Curing behavior and glass transition temperatures of epoxy resins into which reactive diluents were added to control processability were investigated. Heat of cure generated of the epoxy resin was reduced with butyl glycidyl ether(BGE) and phenyl glycidyl ether(PGE) contents. $T_g$ of the resin was decreased with the amount of reactive diluents and it was attributed to increased molecular weight between crosslink points. Cure kinetics of the resins was studied employing autocatalytic reaction model and found that reaction constants decreased as the contents of reactive diluent was increased.

• Journal of the Korean Ceramic Society
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• v.38 no.8
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• pp.693-697
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• 2001

고상반응법으로 이론 밀도의 약 92%의 소결 밀도를 갖는 입방정계의 새로운 이온전도체 L $a_{2-x}$S $r_{x}$M $o_{2-y}$C $r_{y}$ $O_{9-{\delta}}$(x=0, 0.05, y=0, 0.1)를 제조하였다. 교류 복소임피던스는 3$50^{\circ}C$~90$0^{\circ}C$의 온도범위에서 공기중에서 측정하여, EQUIVCRT 모델링 소프트웨어로 해석하였다. 상 전이온도인 58$0^{\circ}C$ 전.후로 임피던스 스펙트럼에 큰 차이가 있었으며, 전기전도도는 L $a_2$M $o_2$ $O_{9}$ 시편의 경우 7$50^{\circ}C$에서 3$\times$$10^{-2}$ S$cm^{-1}$ /로 우수하였으며, 활성화 에너지는 고온 상 영역에서는 0.89 eV, 저온 상 영역에서는 1.12 eV이었다. 순수한 L $a_2$M $o_2$ $O_{9}$과 비교하여 Cr 치환효과는 크지 않았으나, Sr 치환 시에는 상 전이온도의 감소와 전기전도도의 증가 현상을 보였으며, 전이온도 부근에서의 전기전도도 변화 폭은 작았다.다.

• Korean Journal of Materials Research
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• v.4 no.6
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• pp.710-714
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• 1994

We determine the Curie temperature of thin gadolinium films by the measurement of magnetization as a function of temperature. From these data, we observe the Curie temperature shift in films from the bulk value, and also see the systematic behavior of this shift with thicknesses of films, that is, the larger the shift is, the thinner the film is. In this paper, we analyze and explain these results in light of finite-size scaling theory.

• Journal of the Korean Magnetics Society
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• v.7 no.5
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• pp.225-231
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• 1997

Sulphur Spinel $Co_{0.95}Fe_{0.05}Cr_2S_4$ has been studied with Mossbauer Spectroscopy between 4.2 K and room temperature. The $Fe^{2+}$ ion in a tetrahedral site is the Jahn-Teller active and the dynamic Jahn-Teller distortion starts below the magnetic ordering temperature. The distortion cause a quadrupole shift to appear which increases with decreasing temperature. The magnetic hyperfine field has a maximum at 100 k and then decreases with decreasing temperature. The magnitude of the interaction ratio R between the electric quadrupole and magnetic dipole interaction increases from 0 near the magnetic ordering temperature to 5.4 at 4.2 K. The optimum values of 0, the polar angle of the magnetic hyperfine field with respect to the principle axis of the electric field gradient (EFG) remains zero and the asymmetry of the EFG n is about 0.25. The simulations of Mossbauer spectra coincidence with the experimental results.

• Journal of the Korean Chemical Society
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• v.40 no.6
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• pp.394-400
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• 1996

The conformational transitions of oligopeptide -(HPPHPPP)$_n$- (H: hydrophobic amino acid, P: polar amino acid) which becomes cross linked-dimer are detected at various temperatures, pHs, ionic strengths, and the concentrations of denaturant. In this study, the transitions of oligopeptide due to denaturant, and those due to temperature are theoretically studied. Oligopeptide 20R as chain-dimer and guanidum-HCl as denaturant are used(20R, which contains 10 interchain and /or 10 intrachain electrostatic repulsions). Alpha helix-coil transitions by denaturant are very steep. This shows that the denaturations have transition states of, presumably all helical forms and random coils. The transitions by temperature are smoother than those by the concentration of denaturant. At low temperature the oligopetides which contain long helices exist more than those which contain short helices. As temperature rises, the mole fractions of the partially denatured oligopeptides increase. So the partially denatured oligopeptides are widely distributed at the transition temperature.

• Korean Journal of Soil Science and Fertilizer
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• v.24 no.3
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• pp.200-205
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• 1991

To evaluate cold tolerance of rice cultivars on the basis of a relationship between cold tolerance in the field test and a biochemical character, transition-temperature of respiratory activity of mitochondria(TRM) which were isolated from different parts and at different growth stages and from etiolated rice seedling was investigated, and its relationship with degree of cold tolerance(DCT) in the field experiment was studied. The results obtained were summarized as follows. 1. The transition-temperature of respiratory activity of mitochodria (TRM) isolated from etiolated seedling ($25^{\circ}C$, two week-grown in the dark) of cold tolerant cultivars tended to be low, while that of cold susceptible cultivars to be high. 2. The correlation between TRM of etiolated seedling and the degree of cold tolerance(DCT) was $r=0.8935^{**}$ in 1988 and $r=0.8236^{**}$ in 1989. The correlation coefficient between TRM of 4-leaf seedling and DCT was $0.6239^{**}$ 3. TRM of young panicle was correlated with DCT except a few varieties. 4. TRM of seedling increased with growth as $12.5^{\circ}C$, $14.5^{\circ}C$, $15.5^{\circ}C$ and $16.5^{\circ}C$ at 1, 2, 3~4 and 5weeks respectively. 5. The transition temperature of mitochondrial respiratory activity was not significantly influenced by growth stages as $15.0{\sim}16.0^{\circ}C$ in Pungsanbyeo and $17.0{\sim}18.0^{\circ}C$ in Satbyelbyeo, while it was significantly different depending upon the degree of cold tolerance(tolerant, medium, susceptible).

• Electrical & Electronic Materials
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• v.6 no.1
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• pp.15-21
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• 1993

Silane과 Disilane를 사용하여 화학증착법으로 제작한 다결정 실리콘의 미세구조를 증착온도의 변화에 따라 조사하였다. Silane과 Disilane의 증착온도는 각각 550에서 640.deg.C와 485에서 620.deg.C로 변화시켰다. Disilane은 silane에 비해 반응성이 크고 비정질에서 결정으로 변하는 전이온도는 약 20.deg.C정도 높았다. 전이온도에서 증착한 시편은 실리콘 source에 관계 없이 (311)조직의 거친 표면으로 되어있었다. 900.deg.C에서 열처리하는 동안 비정질로 부터는 (111)쌍정립계를 갖는 수지상의 결정성장을 하였다. 반면에 다결정 상태로 증착한 시편은 열처리하는 동안 구조가 거의 변하지 않았고 매우 작은 결정립으로 이루어진 주상구조를 하였다.