• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 1999년도 추계학술대회논문집
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• pp.49-52
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• 1999

In the present study the tensile test was carried out for steel sheets to offer the database for the material characteristics at various temperature condition. The results are constructed with tensile strength total elongation Lankford vale and the flow curve and these can be employed usefully into the analyzing program as input data for the sheet metal forming processes at warm condition.

• 열처리공학회지
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• 제3권2호
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• pp.20-31
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• 1990

This investigation has been carried out to make clear the effect of deformation temperature, strain rate and grain size on the tensile properties of 304L stainless steel. Tensile properties of the metastable austenitic 304L steel remarkably influenced by deformation temperature. Tensile strength increased with decreasing deformation temperature and the elongation showed maximum value near $40^{\circ}C$. In order to obtain the high elongation, a large amount of deformation is available in austenite before martensitic transformation and the martensite has to be induced gradually. Tensile strength and elongation increased with decreasing grain size. The temperature representing the maximum elongation shifted to low temperature and the peak width of elongation became broaden with decreasing austenite grain size. The volume fraction of strain induced martensite decreased with decreasing austenite grain size. As the strain rate increase, the temperature representing the maximum elongation value shifted to high temperature and volume fraction of strain induced martensite decreased.

• 한국잠사곤충학회지
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• 제14권2호
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• pp.105-112
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• 1972

팽윤견사를 수중에서 인장시킬 경우, 인장속도 및 팽윤정도의 차이가 견사의 하중신장곡선에 미치는 영향을 조사하였다. 인장시험은 Tensilon을 사용하였고, 절단시 강도, 신도 및 인장저항도를 조사한바 다음과 같은 결과를 얻었다. 1. 팽윤견사의 절단강도는 인장속도의 증가와 더부러 높아지나 절단신도는 감소하였다. 2. 견사를 팽윤(90$^{\circ}$, 15분)시켜 저속(4mm/분)으로 인장하면 견사의 macrofibril의 분리절단상태가 chart 상에 기록되었다. 3. 9$0^{\circ}C$로 장시간 팽윤처리(60분)하면 절단강도는 현저히 감소하고, 절단신도는 증가의 경향을 보였다. 4. 초기인장저항도는 인장속도 및 팽윤정도의 차이에 의하여 영향된다. 즉 고속인장은 초기인장저항도를 높이지만 팽윤도의 증가는 감소시켰다.

• 한국재료학회지
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• 제24권1호
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• pp.1-5
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• 2014

This study is experimentally investigated whether or not a relationship exists between the mechanical properties and damping capacity of cold-rolled 316 L stainless steel. Deformation-induced martensite was formed with surface relief and directionality. With the increasing degree of deformation, the volume fraction of ${\varepsilon}$-martensite increased, and then decreased, while ${\alpha}^{\prime}$-martensite increased rapidly. With an increasing degree of deformation, tensile strength was increased, and elongation was decreased; however, damping capacity was increased, and then decreased. Tensile strength and elongation were affected in the ${\alpha}^{\prime}$-martensite; hence, damping capacity was influenced greatly by ${\varepsilon}$-martensite. Thus, there was no proportional relationship between strength, elongation, and damping capacity.

• 소성∙가공
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• 제10권2호
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• pp.101-110
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• 2001

The thermal problem of press work is classified into two cases. First, the temperature of forming die passively rises due to the heating effect of plastic deformation. The warm forming is the second case in which the external heating is applied to the die and blank holder. So, the purpose of this study is to provide database for the forming characteristics at various temperature conditions. In this study, the tensile test was carried out for the commercial steel sheets such as SCPI and SCP3C with the thickness of 0.7mm and 1.4mm respectively. The tensile strength, total elongation, Lankford value and the flow curve have been obtained at the temperature of $25^{\circ}C$, $50^{\circ}C$, $100^{\circ}C$, $150^{\circ}C$, $200^{\circ}C$, $250^{\circ}C$ and $300^{\circ}C$, respectively. From the results, we can see that both the tensile strength and total elongation decrease as the temperature increases. In the light of anisotropy, the effect of thickness is dominant than the material specs. For the temperature dependency of flow curves, there are only small differences for the work-hardening exponent, and the strength intensity decreases monotonically as temperature increases. The present results we useful as input data for the analysis of sheet metal forming processes with the various temperature conditions.

• 한국재료학회지
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• 제27권12호
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• pp.643-651
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• 2017

Four types of high Mn TWIP(Twinning Induced Plasticity) steels were fabricated by varying the Mn and Al content, and the tensile properties were measured at various strain rates and temperatures. An examination of the tensile properties at room temperature revealed an increase in strength with increasing strain rate because mobile dislocations interacted rapidly with the dislocations in localized regions, whereas elongation and the number of serrations decreased. The strength decreased with increasing temperature, whereas the elongation increased. A martensitic transformation occurred in the 18Mn, 22Mn and 18Mn1.6Al steels tested at $-196^{\circ}C$ due to a decrease in the stacking fault energies with decreasing temperature. An examination of the tensile properties at $-196^{\circ}C$ showed that the strength of the non-Al added high Mn TWIP steels was high, whereas the elongation was low because of the martensitic transformation and brittle fracture mode. Although a martensitic transformation did not occur in the 18Mn1.9Al steel, the strength increased with decreasing temperature because many twins formed in the early stages of the tensile test and interacted rapidly with the dislocations.

• 한국임상수의학회지
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• 제13권2호
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• pp.184-194
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• 1996

A comparative study of three absorbable suture materials of chromic catgut, Dexon II (a polyglycolic acid suture with a polycaprolate coating system) and Coated Vicryl (a polyglactin 910 suture with a glycolide-lactide-calcium stearate coating system) was undertaken in terms of tensile strength, breaking elongation, appearances of the suture materials in the subcutaneous layer of rats and of tissue reaction in the intramuscular layer of rats. The initial tensile strength of chromic catgut and the tensile strength after 21 days were about 1.55 kg and 0.19 kg, respectively. Those of Dexon II were about 2.01 kg and 0. 20 kg, respectively. Those of Coated Vicryl were about 2.39 kg and 0.48 kg, respectively. Coated Vicryl showed the highest tensile strength among the three materials during the whole period. On the other hand, Dexon II showed the highest breaking elongation among the three materials during the first week. But the breaking elongation of Dexon II rapidly continuously decreased during the whole period. The appearances of the suture materials in the subcutaneous layer of rats showed that chromic catgut was the fastest among the three materials, whereas it formed comparatively much connective tissue. The intramuscular absorption rate and tissue reaction of Dexon II were similar to those of Coated Vicryl. The intramuscular absorption rate of these was fairly late when compared with chromic catgut. And the tissue reaction appearance of these showed the formation of a granuloma with foreign body giant cells, macrothages and epitheloid cells by the 28th day in the experimental period.

• Archives of Plastic Surgery
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• 제35권6호
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• pp.659-662
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• 2008

Purpose: Silicone gel sheet(SGS) is used for preventing and treating keloid or hypertrophic scars. Because the product is weak in tear strength and adherence, it requires several replacements, which requires high cost. As a solution for this problem, we developed a new silicone gel sheet, named as Scar Clinic, and confirmed its physical properties. Methods: Tensile strength, elongation rate, adhesiveness, and water vapor transmission rate were experimentally compared between the most commonly used SGS product and the Scar Clinic. Results: The newly developed SGS showed better results compared to the existed SGS in regards to tensile strength, elongation rate, adhesiveness, and water vapor transmission rate. Conclusion: The Scar Clinic showed higher durability and flexibility. It will be a useful product for treating scars clinically.

• 한국수산과학회지
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• 제32권4호
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• pp.395-398
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• 1999

Chitosan을 이용하여 필름을 제조하여 chitosan의 탈아세틸화도와 분자량, chitosan의 농도, pH등에 따른 chitosan 필름의 인장강도, 인장율 및 수분 투과도 등을 조사한 결과는 다음과 같다. Chitosan 조제조건으로는 $47\%$ NaOH로 $130^{\circ}C$에서 3시간이상 처리시켰을 때 탈아세틸화도의 변화는 적은데 비해 분자량의 감소는 크게 나타나 상업적으로 이용시 3시간 이하로 처리하는 것이 바람직하였다. Chitosan의 탈아세틸화도, 분자량, pH, 농도에 따른 필름의 인장강도, 인장율 및 수분 투과도의 결과는 탈아세틸화도가 높아짐에 따라 인장강도, 인장율, 수분 투과도 등은 감소하였으며, 분자량이 적어짐에 따라 인장강도, 인장율, 수분 투과도등은 감소하는 것으로 조사되었다. pH가 높아짐에 따라 인장강도와 수분 투과도는 감소하였으나 인장율에 있어서는 증가하는 것으로 나타났다. 그리고 chitosan 농도가 높아짐에 따라 인장율과 수분 투과도는 감소하였으나 인장강도는 증가하는 것으로 조사되었다.

• 열처리공학회지
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• 제12권3호
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• pp.231-239
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• 1999

Volume fraction and morphology of retained austenite, tensile properties of TRIP type high strength steel sheet with Fe-C-Si-Mn-Cu chemical composition have been investigated. The retained austenite of granular, bar and film type existing in specimen was obtained after intercritical annealing and austempering. The granular type retained austenite increased with increase of intercritical annealing and austempering temperature. With increase of intercritical annealing temperature, retained austenite and carbon contents increased. Maximum contents of retained austenite was obtained by austempering at $400^{\circ}C$. The maximum tensile strength was obtained by austempering at $450^{\circ}C$ and maximum elongation was obtained at $400^{\circ}C$. T.S${\times}$E.L value increased with increase of retained austenite contents due to the elongation strongly controlled by contents of retained austenite, but tensile strength was affected with various factors such as bainitic structure etc.