• 폴리머
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• 제26권4호
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• pp.468-476
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• 2002

순수한 PAN 섬유의 예비산화와 가수분해의 과정을 통하여 제조된 oxy-PAN은 염기와 산용액에 담그었을 때 신장과 수축 거동을 보임이 알려져 있다. 본 연구에서는, 염기 (NaOH) 용매에서 약 30%의 신장과 산 (HCl) 용매에서 30∼50%의 수축 거동을 관찰하였다. 기계적 특성에 대한 실험에서, oxy-PAN 섬유가 수축되었을 때 향상된 기계적 특성을 나타내었다. 이러한 거동과 기계적 특성은 인체의 근육과 선형 구동체의 그것들과 유사하였다. NaOH와 HCl 용액에서 oxy-PAN 섬유의 길이가 변화하는 중요한 요인으로는 친수화 또는 소수화 구조의 전환에 의한 영향이다. 다른 요인으로는 oxy-PAN 섬유와 용액간의 이온과 물의 교환, 이온의 농도차에 의한 삼투압 등이 영향을 준다. Oxy-PAN 섬유의 신장 및 수축과 기계적 특성에 영향을 미치는 여러 가지 요인들을 규명하기 위한 보다 많은 연구가 필요하지만, 본 연구실에서 제조된 oxy-PAN 섬유가 인공 근육 및 선형 구동체로 적용될 수 있는 충분한 가능성이 있음을 제시한다.

• 한국의류학회지
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• 제21권4호
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• pp.710-717
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• 1997

An investigation made of fabric strength & elongation and the lock stitch seam strength & elongation by stitch density (N1.5; 26 stitches/3 cm, N2.0; 19 stitches/3 cm, N2.5; 14 stitches/3cm) depending on methods of. sample prepariation (angle variations of unseamed sample and overlapping way of seamed sample) It found maximum stitch density that results of the seam strength test was highist in each angle of bias. The results obstained were as follows: 1. As the results of fabric strength and elongation tests as a function of angle of bias, breaking strength were that warp and weft angles (0$^{\circ}$, 90$^{\circ}$) were much higher than bias angles (20$^{\circ}$, 30$^{\circ}$, 45$^{\circ}$, 60$^{\circ}$) . And otherwise breaking elongation were that 45$^{\circ}$ angle of bias were highest and were that the warp & weft way were lower. 2. As the results of the seam strength tests by the stitch density under samples of same angles, the maximum stitch density were those; under 0$^{\circ}$/0$^{\circ}$, 60$^{\circ}$/60$^{\circ}$:F1, F2-N2.0, F3-N1.5, under 20$^{\circ}$/20$^{\circ}$, 30$^{\circ}$/30$^{\circ}$, 45$^{\circ}$/45$^{\circ}$: F1-N2.5, F2-N2.0, F3-N1.5, under 90$^{\circ}$/90$^{\circ}$: F1, F2, F3-N1.5. 3. As the results of the seam strength tests by the stitch density under samples of symmetry angles, the maximum stitch density were those; under 20$^{\circ}$/-20$^{\circ}$, 30$^{\circ}$/-30$^{\circ}$, 60$^{\circ}$/-60$^{\circ}$: F1, F3-N1.5, F2-N2.0, under 45$^{\circ}$/-45$^{\circ}$: F1, F2-N2.0, F3-N1.5.

• 열처리공학회지
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• 제30권3호
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• pp.106-112
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• 2017

In this study dual-phase steels with different ferrite grain size and martensite fraction were fabricated by varying micro-alloying elements and intercritical anneling temperatures, and then the tensile properties were investigated in terms of yield and tensile strengths, elongation, and yield ratio. The addition of micro-alloying elements reduced ferrite grain size, and the increased intercritial transformation tempeature increased the martensite fracton. The tensile test results showed that yield and tensile strengths of all the steel specimens increased with increasing the martensite fraction. However, the elongation and yield ratio were differently changed according to variations in the morphology and carbon content of martensite, ferrite grain size, and precipitates resulting from the addition of micro-alloying elements and intercritical annealing.

• 한국재료학회지
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• 제17권11호
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• pp.601-605
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• 2007

The tribological properties of acrylonitrile-butadiene rubber (NBR) filled with two kinds of carbon black filler were examined. Different types of Semi-Reinforcing Furnace (SRF), and High Abrasion Furnace (HAF) blacks were used as filler material to test the influence of carbon black particle size on the friction and wear of NBR. Results from tribological tests using a ball on disk method showed that the smaller HAF particles were more effective for reducing the wear of NBR during frictional sliding. The hardness, elastic modulus at 100% elongation, and elongation at break were measured to examine the correlation between the effects of carbon black on the mechanical and tribological properties of the NBR specimens. The wear tracks of the NBR specimens were observed with scanning electron microscopy (SEM). The wear tracks for NBR with different ratios of SRF and HAF showed clearly different abrasion patterns. Mechanisms for the friction and wear behavior of NBR with different sizes of carbon black filler were proposed using evidence from wear track observation, as well as the mechanical and tribological test results.

• 열처리공학회지
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• 제23권5호
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• pp.263-268
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• 2010

This investigation was focused on the low temperature tensile properties, phase change, changes in nitrogen content and corrosion resistance in the 22Cr-5Ni-3Mo duplex stainless steel after high temperature gas nitriding and solution annealing (HTGN-SA). From the HTGN-SA treatment, the duplex (ferrite + austenite) phase changed into austenite single phase. The nitrogen content of austenite single-phase steel showed a value of ~0.54%. For the HTGN-SA treated austenitic steel, tensile strength increased with lowering test temperature, on the other hand elongation showed the maximum value of 28.2% at $-100^{\circ}C$. The strain-induced martensitic transformation gave rise to lead the maximum elongation. After HTGN-SA treatment, corrosion resistance of the austenite single-phase steel increased remarkably compared with HTGN- treated steel.

• 한국주조공학회지
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• 제22권1호
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• pp.17-25
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• 2002

Recently, many studies have been carried out to process on the purpose of lightness in a transport parts because of the saving energy, the environmental problem. The cast-forging process can be expected to lower costs without decreasing the mechanical properties. So, the finest microstructure is needed to get for applying the cast-forging process with Al-Si alloy because the microstructure affects to the cast-forging process. For refinement treatment of eutectic Si and Al solid-solution phase, Sr and TiB were added in Al-Si alloys. The finest microstructure could be observed when 0.075 wt.%Sr and 0.1 wt.%TiB were added respectively. In this case, tensile strength and elongation much more increased than as casting. After high temperature deformation simulation test with grain refinement specimens was carried out, about 70N per unit $area(mm^2)$ of specimen was confirmed. After hot forging, tensile strength and elongation were increased. It was considered because casting defect was removed by compressive working.

• 한국융합학회논문지
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• 제10권6호
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• pp.281-286
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• 2019

현대인에게 외모는 경쟁력의 수단이며 이러한 현대인의 욕구에 위해요소로 작용하는 요인 중 하나는 백모(白毛)이다. 백모를 커버하여 타인에게 아름다운 외모를 표출해야 하는 현대인을 위하여 백모 염모제 시술 후 모발분석을 실시하였다. 실험결과 1N-3N 화학염모제의 control 대조군과 1N부터 3N 실험군 간에 최대하중, 최대 인장 강도, 최대 신장률, 파단하중, 파단강도, 파단 신장률, 평가구간에 따른 최대 모듈러스 및 tangential modulus가 대체적으로 유의적인 차이를 보였다. 최대 하중과 최대 인장강도, 파단 하중과 파단 강도가 대조군에 비해 커다란 경향을 보인 반면 최대 신장률과 파단 신장률은 대조군이 가장 큰 값으로 실험군 처리에 따라 신장률이 감소하였다. 평가구간에 따른 최대 모듈러스와 tangential modulus는 대조군에 비해 1N-3N 실험군들이 0~0.15와 0.15~2.5 등 모든 strain 구간에서 대체적으로 높게 나타났다. 백모 커버용 산화염모제의 시술 전후 모발의 미용학적 변화에 대한 연구를 바탕으로 올바른 화학염모제 제품의 선택, 적당한 도포량 및 방치시간 등을 효과적으로 선택할 수 있는 기초자료로 활용되리라 사료된다.

• 한국생산제조학회지
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• 제26권4호
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• pp.430-435
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• 2017

The effect of the surface profile on CFRP and aluminum metal bonding was studied. A small number of steps were made on the aluminum surface, and the shear stress and elongation were measured using a shear test after bonding with an autoclave method. As the number of surface steps increased, the shear stress and elongation increased. The surface bonding strength increased because of the effect of the mechanical and chemical bonding. When the number of effective stages was exceeded, the shear strength decreased again due to the aspect ratio of the step and the reduction of the penetration effect of the resin into the groove.

• 한국응용과학기술학회지
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• 제17권3호
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• pp.198-202
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• 2000

PVA blend films were prepared by solution blending method for the purpose of useful antibiotic polymers. Characteristics properties of blending films such as elongation and tensile strength were determined. Tensile strength and elongation were rapidly reduced as increasing the blending ratio of natural polymer. Blend films were found that phase separation was occured as more than 25wt% increasing the blend ratio of chitosan. Also, The antibiotics of blend films were examined against gram(+) and gram(-) by disk susceptibility test. As a result, kind of blending films to show the highest antibiotics was chitosan 20wt% and the selectivity of mold strain was observed.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2010년도 춘계 학술발표회
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• pp.305-313
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• 2010

HDPE smooth and textured GMs were cut into dumbbell shape and notched where depth of the notch produced a ligament thickness of 90% to 10% of the nominal thickness of the specimen at 10% interval. Yield stress and elongation were measured of those samples and plotted on Graph. Yield stress and elongation at yield point decreases gradually as the notch depth is increased. Both installations damaged and notched GMs were used to understand stress crack behavior. Intact sample were notched in such a manner that the depth of notch produced a ligament thickness of 80% of the nominal thickness of the specimen. Installation damaged samples were not notched. Stress Crack Resistance behavior was observed using NCTL Test at $50{\pm}1^{\circ}C$ at different yield stresses immerging with pH 4 and pH 12 buffer solutions. Significant difference was observed in both cases.