• 한국해양공학회지
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• 제13권1호통권31호
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• pp.62-69
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• 1999

67Ni-22Cr-10Al-1Y and $ZrO_2-8Y_2O_3$ were coated on the substrate surface of ST304 and Al2024 by the plasma spraying method. The adgesion of the films varies depending on the substrates and the laminating method. In the case of STS304, the cracks were observed at thermal shock temperature difference ${Delta}T$ of $900^{circ}C$ in the non functionally gradient material(NFGM) and at $1100^{circ}C$ in the functionally gradient material(FGM). The film adhesion of the FGM is better than that of the NFGM in ST304. The cumulative AE count of the FGM of STS304 increased continuously at the bending test. But the NFGM of STS304 showed discontinuity of the AE count. The total AE count for the FGM of STS304 decreased as the number of thermal shock increased, and this tendency was evident as the thermal shock temperature difference increased.

• 한국가금학회지
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• 제43권4호
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• pp.213-218
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• 2016

본 연구는 고온 스트레스 하에 타우린 첨가가 육계의 간에서 heat shock protein 70(hsp 70) 및 cell free system 상태에서 단백질 합성에 미치는 영향을 조사하였다. 공시동물은 1일령 육계 120수를 2주간 사육 후, 대조(CO, $24^{\circ}C$)와 고온스트레스 처리($34^{\circ}C$)에서 타우린을 공급하지 않은 처리구(HO)와 타우린 0.1%를 공급한 처리구(HT)로 나누어 3처리 4반복, 반복 당 10수씩 배치하였다. 고온 스트레스는 3, 6, 9, 12일간 진행하였다. 최종 체중과 간 무게는 HO와 HT가 CO보다 유의적으로 낮았다(P<0.05). 그러나 타우린을 첨가한 HT은 HO보다 유의적으로 높았다(P<0.05). 육계 간에서 hsp70 발현은 HO가 CO와 HT보다 유의적으로 높았으나(P<0.05), CO와 HT는 유의적인 차이가 없었다. In vitro 실험에서 고온 및 타우린은 21일령 육계 간의 총 단백질 합성률에 영향을 미치지 않았다. 따라서 타우린 섭취가 in vivo 육계의 성장에서 고온 스트레스를 완화시키지만, 생체 내의 단백질 합성에 직접적인 영향을 미치지 않는 것을 보이며, 이러한 결과는 타우린이 다양한 생리학적 기전을 통해 단백질 turnover 대사에 간접적으로 영향을 미칠 수 있다는 것으로 사료된다.

• 한국세라믹학회지
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• 제56권2호
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• pp.184-190
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• 2019

To improve resistance in thermal shock of zirconia setter which is frequently and repeatedly exposed to high temperature, high degree of porosity and control of thermal expansion are needed for which the fused CSZ (CaO stabilized zirconia) is used to produce the zirconia setter. In the present study, the effects of sintering temperature, cool down condition, addition of CaO stabilizer, and addition of other additives on phase transition and thermal expansion behavior of the fabrication process of zirconia setter, were examined. The zirconia setter, fabricated with fused CSZ at 1550℃, exhibited 20.4 MPa of flexural strength, 6.8% of absorbance, and 27.9% of apparent porosity. The rapid change in thermal expansion of zirconia setter is observed at temperature around 800℃, and it was reduced by low firing temperature, slowed cooled down, and addition of CaO.

• 터널과지하공간
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• 제5권1호
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• pp.22-40
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• 1995

Thermomechanical characteristics of rocks such as thermal shock, thermal expansion, thermal cracking were experimentally investigaed using Iksan granite, Cheonan tonalite and Chung-ju dolomite to obtain the basic data for proper design and Chung-ju dolomite to obtain the basic data for proper design and stability analysis of underground structures subjected to temperature changes. The effect of thermal shock did not appear when the heating speed was under 3$^{\circ}C$/min. and there existed little difference between multi-staged cyclic heating and single-cycled heating. Thermal expansion of rocks was affected by mineral composition, crack porosity and the degree of thermal craking. In quartz-beraring multimineralic rocks such as Iksan granite and Cheonan tonalite, the thermal expansion coefficient increaseed continuously with temperature rise, but that of Chung-ju dolomite which was a monomineralic rock showed a constant value for the temperature above 250$^{\circ}C$, Chung-ju dolomite yielded the lowest critical threshold temperature(Tc) of 100$^{\circ}C$ and unstable thermal cracking was initiated above the new threshold temperature(Tc')of 300$^{\circ}C$. Above Tc' thermal cracks grew but they were not interconnected. Iksan granite showed closing of microcracks to the temperature of 100$^{\circ}C$, then expanded linearly to Tc of 200$^{\circ}C$. Above Tc, thermal cracking was initiated and progressed rapidly and almost all the grain boundaries were cracked at 600$^{\circ}C$. Cheonan tonalite also showed similar behavior to iksan granite except that Tc was 350$^{\circ}C$ and that thermal cracks propagated more rapidly. Thermal expansions calculated by Turner's equation were found to be valid in predicting the thermal expansion and cracking behavior of rocks.

• 대한의용생체공학회:학술대회논문집
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• 대한의용생체공학회 1998년도 추계학술대회
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• pp.74-75
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• 1998

The present study employs weak shock theory and bio-heat transfer function to predict the temperature rise due to nonlinear propagation of high amplitude ultrasound. The theory shows that, for the focused ultrasound which is assumed to have an gaussian beam profile and has the focal intensity of $1000W/cm^2$, the temperature rise of liver tissue exposed for 1 second to the energy lost during nonlinear propagation goes up to about $30^{\circ}C$. This indicate that it is necessary to consider the nonlinear propagation induced heating enhancement when setting exposure condition of high intensity focused ultrasound used for cancer thermotherapy.

• 한국추진공학회지
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• 제3권1호
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• pp.65-71
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• 1999

마하수 2.5인 모델 스크램제트 연소기내에서 초음속 수소-공기 화염에 대한 충격파의 영향을 실험적으로 연구하였다. 본 실험은 충격파가 초음속 화염에 미치는 영향을 연구한 최초의 실험연구이다. 동일한 모양과 크기의 $10^{\cire}$ 쐐기를 연소기 팽창 벽면에 각각 부착시켜 평면경사충격파를 발생시켰고 충격파가 화염에 미치는 영향을 연구하였다. 쉬릴렌 가시화 사진과 벽면정압, 그리고 두개의 다른 공기온도에서의 연소효율을 측정하였으며, 충격파가 없는 경우와 비교하였다. 충격파에 의해서 화염 모양은 크게 변화하였다. 연소효율은 공기온도에 따라 상이한 결과를 보였는데 공기정체온도가 증가하고 연료유량이 증가한 경우에 충격파에 의한 연소효율은 더 좋은 결과를 보였다.

• Journal of Microbiology and Biotechnology
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• 제25권8호
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• pp.1234-1240
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• 2015

Heat shock RNA 1 (HSR1) is described as a "eukaryotic heat-sensing noncoding RNA" that regulates heat shock response in human and other eukaryotic cells. Highly conserved HSR1 sequences have been identified from humans, hamsters, Drosophila, Caenorhabditis elegans, and Arabidopsis. In a previous study, however, it was suggested that HSR1 had originated from a bacterial genome. HSR1 showed no detectible nucleotide sequence similarity to any eukaryotic sequences but harbored a protein coding region that showed amino-acid sequence similarity to bacterial voltage-gated chloride channel proteins. The bacterial origin of HSR1 was not convincible because the nucleotide sequence similarity was marginal. In this study, we have found that a genomic contig sequence of Comamonas testosteroni strain JL14 contained a sequence virtually identical to that of HSR1, decisively confirming the bacterial origin of HSR1. Thus, HSR1 is an exogenous RNA, which can ectopically trigger heat shock response in eukaryotes. Therefore, it is no longer appropriate to cite HSR1 as a "eukaryotic functional noncoding RNA."

• 한국항공우주학회지
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• 제37권6호
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• pp.571-579
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• 2009

에너지 물질과 같이 연소 반응을 하는 압축성 물질을 해석하기 위하여 Hydro-SCCM (Shock Compression of Condensed Matter)이라는 에너지 물질과 비반응 물질을 포함한다중 물질 해석툴을 개발하였다. 고에너지 물질은 강한 충격파와 고온과 고압을 가진 물질경계면에서 높은 변형률을 발생시킨다. 이러한 큰 구배를 가진 현상을 해석하기 위하여 새로운 오일러리안 기법을 사용하였다. 본 논문에서는 현상을 해석하기 위한 수학적 방법과 해석결과를 소개하였다.

• Nuclear Engineering and Technology
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• 제53권9호
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• pp.3112-3121
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• 2021

One of the major factors affecting the life span of a Reactor Pressure Vessel (RPV) is the Pressurised Thermal Shock (PTS). PTS is a thermo-mechanical load on the RPV wall due to steep temperature gradients and structural load created by internal pressure of the fluid within the RPV. Safe operating life of a nuclear power plant is ensured by carrying out fracture analysis of the RPV against thermal shock. Carrying out fracture tests on RPV/large scale components is not always feasible. Hence, studies on laboratory level specimens are necessary to validate and supplement the prototype results. This paper aims to study the fracture behaviour of standard Compact Tension [C(T)] specimens, made of RPV steel 20MnMoNi55, subjected to thermal shock through experimental and numerical investigations. Fracture tests have been carried out on the C(T) specimens subjected to thermal transient load and tensile load to quantify the effect of thermal shock. Crack resistance curves are obtained from the fracture tests as per ASTM E1820 and compared with those obtained numerically using XFEM and a good agreement was found. A quantitative study on the crack tip plastic zone, computed using cohesive segment approach, from the numerical analyses justified the experimental crack initiation toughness.

• 천문학회지
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• 제51권6호
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• pp.185-195
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• 2018

Galaxy clusters are known to host many active galaxies (AGNs) with radio jets, which could expand to form radio bubbles with relativistic electrons in the intracluster medium (ICM). It has been suggested that fossil relativistic electrons contained in remnant bubbles from extinct radio galaxies can be re-accelerated to radio-emitting energies by merger-driven shocks via diffusive shock acceleration (DSA), leading to the birth of radio relics detected in clusters. In this study we assume that such bubble consist primarily of thermal gas entrained from the surrounding medium and dynamically-insignificant amounts of relativistic electrons. We also consider several realistic models for magnetic fields in the cluster outskirts, including the ICM field that scales with the gas density as $B_{ICM}{\infty}n^{0.5}_{ICM}$. Then we perform time-dependent DSA simulations of a spherical shock that runs into a lower-density but higher-temperature bubble with the ratio $n_b/n_{ICM}{\approx}T_{ICM}/T_b{\approx}0.5$. We find that inside the bubble the shock speed increases by about 20 %, but the Mach number decreases by about 15% in the case under consideration. In this re-acceleration model, the observed properties of a radio relic such as radio flux, spectral index, and integrated spectrum would be governed mainly by the presence of seed relativistic electrons and the magnetic field profile as well as shock dynamics. Thus it is crucial to understand how fossil electrons are deposited by AGNs in the ICM and how the downstream magnetic field evolves behind the shock in detailed modeling of radio relics.