• 열처리공학회지
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• 제7권3호
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• pp.199-205
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• 1994

The fracture characteristics and tool life of ceramics and WC, CBN cutting tool when turning heat treated steel STD11($H_RC$ 60) were investigated experimentally to clarify the machinability and optimum tool materials in cutting of difficult-to-cut material with high hardness. Forthermore, the behaviors of the tool wear and failure were examined with regard to cutting force. The hardened steel wore the cutting tool edge rapidily and increased the cutting forces, especially radial force. The tool was worn by the abrasive action. Flank Weat of $Al_2O_3-TiC$ ceramic and WC tool become relatively large and CBN & $Al_2O_3$, ceramic tool had a long life among the tool materials tested. The tool fracture patterns were just like minor cutting wear, flank wear, crater wear, notch wear, chipping. Flank wear rate was accelerated by occurrence of chipping. During the proceeding of machining, it was possible to foresee the catastrophic fracture of tool by abrupt increase of radial force.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 1999년도 제3회 압연심포지엄 논문집 압연기술의 미래개척 (Exploitation of Future Rolling Technologies)
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• pp.356-365
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• 1999

The present study is aimed at developing the TRIP(transformation induced plasticity) aided high strength low carbon steel using reversion process. An excellent combination of elongation over 40% and tensile strength abut 100kgf/$\textrm{mm}^2$ achieved in processing of 0.15C-0.5 Si-6Mn steel by slow heating to intercritial temperature region and accelerated cooling into room temperature. This good combination is caused by TRIP phenomena of retained austenite in steels during deformation. The stability of retained austenite is very important for the good ductility and it depends on the diffusion of carbon and manganeses during heat treatment. The accelerated cooling after holding at annealing temperature retards the formation of pearlite and provides the carbon enrichment in retained austenite in steel, resulting in the increase in elongation of the cold-rolled TRIP steel. On the other hand, heat treating the steel at 600$^{\circ}C$ for 5 hour before cold rolling increases elongation but reduces the amount of retained austenite after reversion processing. It is accounted that the heat treating is effective for the increase in the stability of retained austenite.

• 한국식품저장유통학회지
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• 제13권5호
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• pp.531-537
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• 2006

본 연구는 가열 및 감마선조사 또는 가열-감마선 병용처리가 김치의 저장성 및 품질에 미치는 영향을 평가하였다. 김치의 가열처리를 위한 온도는 $60^{\circ}C$에서 30분이 최적 조건으로 확인되었다. 한편 $60^{\circ}C$에서 30분간 가열처리된 김치에 감마선을 병용처리 할 경우 미생물감소 효과가 증가되어 20kGy의 감마선-가열 병용처리군은 $35^{\circ}C$에서 14일간 가속저장 후에도 미생물이 검출한계 이하로 나타났으며, 관능적 품질 또한 다른 처리군에 비해 높은 평점을 나타내어 김치의 장기안전저장을 위한 최적조건으로 확인되었다. 그러나 가열 및 감마선 조사에 의한 변색 및 경도 감소 등의 품질저하가 발생되어 이를 방지하기 위한 연구가 요구되었다.

• Journal of the Korean Wood Science and Technology
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• 제44권5호
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• pp.776-784
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• 2016

본 연구에서는 pilot scale에서 과열증기를 이용하여 실대재 낙엽송 생재 각재를 열처리하고, 열처리된 낙엽송재의 다양한 물리 역학적 성능과 내후성능을 측정하였다. 또한, 이를 고온 열기 열처리한 낙엽송재의 물성과 비교하였다. 생재로부터 할렬 발생이 억제된 상태로 과열증기 열처리된 낙엽송재의 갈색부후균과 백색부후균에 대한 저항성과 종압축강도는 증가한 반면에 밀도와 평형함수율 및 수축률과 휨강도는 관행 열처리재보다 낮게 측정되었다. 과열증기 목재 열처리는 다량의 수분에 의해 열전달이 빠르고 열가수분해가 촉진되기 때문에 유사한 시간과 온도에서 열기를 이용하여 관행 열처리한 경우보다 열처리 효과가 높게 나타났다. 따라서 과열증기 열처리 방법은 생재를 할렬 없이 열처리할 수 있으며, 관행 열처리 방법보다 낮은 온도 또는 짧은 열처리 시간으로도 동일한 열처리 효과를 발현시킬 수 있다. 즉, 열처리에 소요되는 시간과 에너지를 줄일 수 있다.

• 펄프종이기술
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• 제45권5호
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• pp.49-55
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• 2013

To explore the paper materials for restoration of the Annals of the Joseon Dyansty, durability of the three type of the traditional Korean Papers were estimated in this study, through moist heat artificial aging test. Three types(D, F, and G) which showed the best preservation performance in dry heat and UV treatment in the previous study were selected and artificial accelerated aging treatment with moist-heat process was conducted; the viscosity change rate was D>G>F; folding endurance G>D>F; $L^*$ value F>D>G; $a^*$ and $b^*$ change rate D>G>F; brightness decrease rate D>G>F, suggesting paper F showed the least change rate in physical/optical properties. Also the CLSM image observation showed fair coherence among fibers and confirmed paper mulberry. And in FDI extraction from each sample, paper F showed the highest value. Overall, paper F (traditional glossy paper) showed the highest stability against thermal treatment. It confirms that paper F is suitable as restoration paper for tributary remains including the annals of the Joseon Dynasty for its steady strength/viscosity decrease rate and color change rate.

• 자연과학논문집
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• 제11권1호
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• pp.151-157
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• 1999

승화성이 우수한 분산염료를 사용하여 면포에 대한 열 전사 염색성의 최적조건을 알아보기 위하여 온도, 시간, 농도에 따른 전사 염색에 대하여 연구하였다. 이 최적조건에 따라 팽윤제를 첨가한 후의 열 전사 염색성과 전 처리된 면포의 열 전사 염색성 및 분자량에 따른 열 전사 염색성을 검토하였으며, 세탁견뢰도와 일광견뢰도를 측정하여 열 전사날염에 대한 염색견뢰도를 측정하였다. 분산염료를 사용하여 면포에 대한 열 전사날염의 최적조건은 염료용액의 농도는 5%로, 처리온도가 $200^{\circ}C$, 처리시간은 3분에서 열 전사 염색성이 우수하였다. 면포에 대한 전처리의 시간이 길어질수록 열 전사 염색성이 향상되었으며, 팽윤제로는 Glycerin이 우수하였고, 혼합처리보다는 전처리가 열 전사 염색성이 우수하였다. 분자량에 따른 열 전사 염색성은 혼합처리의 경우 분자량이 작을수록 열 전사 염색성이 향상되었으며, 분자량이 커짐에 따라 열 전사 염색성이 나빠짐을 나타내었다. 그러나 전처리의 경우는 분자량에 큰 영향을 받지 않음을 나타내었다. 열 전사 날염된 면포의 세탁견뢰도는 염료의 분자량이 작은 것이 우수하였고, 일광견뢰도는 염료의 분자량이 큰 것이 보다 우수한 견뢰성을 나타내었다.

• 열처리공학회지
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• 제6권4호
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• pp.204-212
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• 1993

The preparation of $TiO_2$ fine particles from $TiCl_4$ and oxygen by the vapor-phasereaction was investigated at $850^{\circ}C$ with an emphasis on the effect of its experimental conditions on the crystal type of the products. Anatase $TiO_2$ particles prepared by experiment were used to study anatase-rutile transition by calcination temperature, the additives and gas atmosphere. The results were as follows. The kinetics of anatase-rutile transition was well agreed with A vrami equation, and the activation energy of transition was 35kcal/mol. The addition of CuO in anatase $TiO_2$ particles accelerated the anatase-rutile transition, and its transition was retarded in vaccum.

• 한국건축시공학회지
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• 제21권2호
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• pp.97-104
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• 2021

본 연구에서는 산업부산물을 전량 활용하여 포틀랜드 시멘트를 대체할 수 있는 비소성 시멘트 개발을 목표로 하였다. 이를 위해 고로슬래그 미분말과 F급 플라이애시, C급 플라이애시를 사용하여 양생방법에 따른 비소성 시멘트 모르타르의 물리적 특성에 대해 파악하였다. 연구 결과, 증기양생 후 열처리 과정을 통해 강도성능과 흡수율이 향상되는 것으로 나타났다. 결정상 분석을 통해 열처리 후 수화물의 촉진을 확인하였으며, 결합재는 치밀한 내부구조를 형성하게 된다.

• 열처리공학회지
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• 제6권2호
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• pp.98-106
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• 1993

Ultra high carbon steel (Fe-1.4%C) was prepared by means of a high frequency induction furnace. The preferred nucleation site of martensite was observed. The changes of hardness and impact thoughness due to tempering temperatures, and the spheroidization of cementite by controlled -rolling were also studied for the steel. The preferred nucleation site of martensite in the ultra high carbon steel is prior austenite grain boundary. The hardness of the steel is slightly increased up to about $300^{\circ}C$, and then decreased with further tempering temperature. However, the impact energy keeps a almost constant value, independent of the tempering temperature. The spheroidization of cementite is accelerated as the reduction in thickness per rolling pass is increased and the number of the rolling passes becomes greater.

• 한국수산과학회지
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• 제28권6호
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• pp.728-735
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• 1995

The peptidyl prolyl cis-trans isomerase(PPlase, EC 5.2.2.8) from Bacillus stearothermophilus SIC1 was extracted from the cells treated with by lysozyme. PPlase was purified from the cell extracts by heat treatment, ammonium sulfate precipitation, ion exchange chromatography and finally gel filtration (FPLC). The purity of purified the enzyme after Superose 12 column chromatography was examined by sodium dodecyl sulfate polyacrylamide gel electrophoresis(SDS-PAGE). The molecular weight of the purified PPlase was estimated as 18,000 by SDS-PAGE. The 39 amino acid residues from the N-terminus were determined by the protein sequencer. The enzyme showed the optimum pH at 8.0 and was stable at the range of pH 7.0 to 8.0. The enzyme was considerably stable after heat treatment at $60^{\circ}C$ for 30 minutes, and the enzyme was quite stable up to $65^{\circ}C$. The presence of the PPlase in the refolding solution accelerated the isomerization rate of the assay peptide.