• 한국생활환경학회지
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• 제24권4호
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• pp.533-540
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• 2017

This study analyzes the stretchability and clothing pressure of fabrics made from stretchy knit materials, and uses the baseline data to develop various functional clothing made from stretchy knit fabrics. To observe the changes in the stretchability and clothing pressure, we observed the compatibility of the two materials (tricot and power-net), presence of flat seam, fabric layering, and flat seam direction as key variables. A standard test method for stretch properties (ASTM D2594) was used for measuring the stretchability of the material. Clothing pressure measurements were analyzed in terms of the mean and standard deviation values, and the correlation of the stretchability. In the case of tricot, the presence of flat seam increased the stretchability of the fabric regardless of the fabric layering. However, when tricot and the less stretchable power-net were combined, the presence of flat seam did not increase the stretchability. Flat seam did not interfere with or limit the stretchability of the fabric, but they did increase the clothing pressure at the seam. The stretchability had a negative correlation with the clothing pressure except along the flat seam.

• Clinical and Experimental Reproductive Medicine
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• 제44권3호
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• pp.126-131
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• 2017

Objective: Oocyte degeneration often occurs after intracytoplasmic sperm injection (ICSI), and the risk factor is low-quality oocytes. The follicular fluid (FF) provides a crucial microenvironment for oocyte development. We investigated the relationships between the FF volume aspirated from individual follicles and oocyte retrieval, oocyte maturity, oolemma stretchability, fertilization, and development. Methods: This retrospective study included data obtained from 229 ICSI cycles. Ovarian stimulation was performed according to a gonadotropin-releasing hormone antagonist protocol. Each follicle was individually aspirated and divided into six groups according to FF volume ( < 1.0, 1.0 to < 2.0, 2.0 to < 3.0, 3.0 to < 4.0, 4.0 to < 5.0, and ${\geq}5.0mL$). Oolemma stretchability during ICSI was evaluated using a mechanical stimulus for oolemma penetration, that is, the stretchability was assessed by oolemma penetration with aspiration (high stretchability) or without aspiration (low stretchability). Results: Oocyte retrieval rates were significantly lower in the < 1.0 mL group than in the ${\geq}1.0mL$ groups (46.0% [86/187] vs. 67.5%-74.3% [172/255 to 124/167], respectively; p< 0.01). Low oolemma stretchability was significantly more common in the < 1.0 mL group than in the ${\geq}1.0mL$ groups during ICSI (22.0% [13/59] vs. 5.8%-9.4% [6/104 to 13/139], respectively; p= 0.018). There was a relationship between FF volume and oolemma stretchability. However, there were no significant differences in the rates of fertilization, cleavage, ${\geq}7$ cells at day 3, and blastocyst development among all groups. Conclusion: FF volume is potentially associated with the stretchability of metaphase II oolemma during ICSI. Regarding oolemma stretchability, ensuring a uniform follicular size during ovarian stimulation is crucial to obtain good-quality oocytes.

• 센서학회지
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• 제32권6호
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• pp.335-339
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• 2023

Skin-compatible electronics have evolved to achieve both conformality and stretchability for stable contact with deformable biological skin. While existing research has largely concentrated on alternative materials, the potential of Parylene-based thin-film electrodes for stretchable on-skin applications remains relatively untapped. This study proposes an engineering strategy to achieve stretchability using the Parylene thin-film electrode. Unlike the conventional Parylene thin-film electrode, we introduce morphological adaptability via controlled microscale slits in the Parylene electrode structure. The slits-containing device enables unprecedented stretchability while maintaining critical electrical insulation properties during mechanical deformation. Finally, the demonstration on human skin shows the mechanical adaptability of these Parylene-based bioelectrodes while their electrical characteristics remain stable during various stretching conditions. Owing to the ultra-thinness of the Parylene coating, the wearable bioelectrode not only achieves stretchability but also conforms to the skin. Our findings broaden the practical use of Parylene thin-film bioelectrodes.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2016년도 제50회 동계 정기학술대회 초록집
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• pp.351.1-351.1
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• 2016

While conventional electronic devices have been fabricated on the rigid and brittle Si based wafer as a semiconducting substrate, future devices are increasingly finding applications where flexibility and stretchability are further integrated to enable emerging and wearable devices. To achieve high flexibility and stretchability, various approaches are investigated such as polymer based conducting composite, thin metal films on the polymer substrate, and structural modifications for stretchable electronics. In spite of many efforts, it is still a challenge to identify a solution that offers both high stretchability and superior electrical properties. In this paper, we introduce a highly stretchable entangled-mesh graphene showing a potential to address such requirements as stretchability and good electrical performance. Entangle-mesh graphene was synthesized by CVD graphene on the Cu foil. To analyze the mechanical properties of entangled-mesh graphene, endurance and stretching tester have been used.

• 한국축산식품학회지
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• 제24권2호
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• pp.156-163
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• 2004

모짜렐라 치즈의 신전성에 영향을 미치는 요인들 중 스타터 종류, 지방함량, 식염함량, 신축 시 온도에 변화를 주어 이러한 조건들이 어떠한 영향을 미치는지를 알아보기 위하여 치즈를 직접 제조한 후 4$^{\circ}C$ 냉장고에 저장하면서 10주 동안 2주 간격으로 신전성, 융해성, 지방유출 및 수용성 질소 화합물의 변화에 관한 실험을 실시하였다. L. bulgaricus를 스타터로 사용한 치즈의 신전성이 우수하였고, 융해성은 수용성 질소화합물의 함량이 저장기간초기에 높거나 그 증가율이 높은 L. bulgaricus 와 L. bulgaricus : Str. thermophilus = 1:2로 스타터를 사용한 치즈가 좋은 경향을 나타냈으며 지방 유출은 L. bulgaricus : Str. thermophilus = 1:3을 스타터로 사용한 치즈가 가장 좋았다. 지방 함량에서는 원유의 지방 함량을 2.0%로 조절하여 제조한 치즈의 신전성이 우수하였으며 융해성과 지방 유출은 원유의 지방 함량이 2.5와 3.0%가 좋은 결과를 나타냈다. 식염 함량이 0.5%일 때 신전성, 융해성과 지방 유출이 약 5주 후부터 저하되어 급격한 품질저하의 결과로 나타났다. 수용성 질소 화합물 함량 변화에서는 식염이 수용성 질소 화합물 억제 효과가 있음을 알 수 있었다. 신전성은 신장 시 온도가 7$0^{\circ}C$인 치즈가 우수하게 나타났으며, 융해성은 신장 시 온도가 6$0^{\circ}C$인 치즈가 우수하게 나타났다. 지방유출은 시료치즈 원 넓이의 2배인 52$\textrm{cm}^2$가 적정 범위로 나타났다.

• 대한기계학회논문집
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• 제17권11호
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• pp.2676-2683
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• 1993

Plane strain punch stretching test(PSST) was performed for various automotive steel sheets. To clarify the effect of tensile properties on plane strain stretchability, the limiting punch height(LPH) values were obtained in plane strain punch stretching test and related to the tensile properties of the materials. The results show that the total elongation El and work hardening exponent n compared to other parameters obtained from tensile test well correlate with the LPH value. In comparision with the Erichsen test and LDH test the PSST can be statistically used as an alternative in assessing the stamping formability of automotive steel sheets with the advantages of good reproducibility and easy testing method.

• 한국의류학회지
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• 제41권6호
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• pp.1098-1108
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• 2017

This paper investigated stretchability with fabric mechanical properties of one-way and two-way stretch fabrics. For this purpose, 1-way and 2-way woven fabrics were prepared using 150d PET/spandex covered yarns with different thermal treatment according to 4 kinds of wet thermal machines subsequently, fabric mechanical properties were measured and compared with regular PET fabrics. In addition, the garment formability of stretch fabrics was predicted and compared to regular fabrics according to wet thermal treatment. The weft stretchability of 2-way stretch fabric was about 10% higher than the 1-way stretch fabric. The compressibility of the stretch fabrics was 1.5 times higher than regular fabrics. The compressibility of stretch fabrics treated with CPB and rope type wet thermal machine showed higher values than other types of wet thermal machines. The bending rigidity of 2-way stretch fabric was lower than 1-way stretch fabric. Shear rigidity of 2-way stretch fabric was higher than 1-way and regular fabrics. Garment formability of 2-way stretch fabric was higher than regular and one-way stretch fabrics. Garment formability of 2-way stretch fabrics treated with wet thermal conditions under low tension showed the highest values.

• 한국재료학회지
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• 제21권3호
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• pp.133-137
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• 2011

Gold have been used as an electrode materials having a good mechanical flexibility as well as electrical conductivity, however the stretchability of the gold on a flexible substrate is poor because of its small elastic modulus. To overcome this mechanical inferiority, the reinforcing gold is necessary for the stretchable electronics. Among the reinforcing materials having a large elastic modulus, carbon nanotube (CNT) is the best candidate due to its good electrical conductivity and nanoscale diameter. Therefore, similarly to ferroconcrete technology, here we demonstrated gold electrodes mechanically reinforced by inserting fabrics of CNTs into their bodies. Flexibility and stretchability of the electrodes were determined for various densities of CNT fabrics. The roles of CNTs in resisting electrical disconnection of gold electrodes from the mechanical stress were confirmed using field emission scanning electron microscope and optical microscope. The best mechanical stability was achieved at a density of CNT fabrics manufactured by 1.5 ml spraying. The concept of the mechanical reinforced metal electrode by CNT is the first trial for the high stretchable conductive materials, and can be applied as electrodes materials in various flexible and stretchable electronic devices such as transistor, diode, sensor and solar cell and so on.

• 반도체디스플레이기술학회지
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• 제14권3호
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• pp.51-55
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• 2015

We have fabricated silver nanowire (AgNW) films as a stretchable and transparent electrode on polydimethylsiloxane (PDMS) substrates using a spray coater. Inherently, they show poor surface roughness and stretchability. To tackle it, we have employed a conductive polymer, poly (3,4-ethylenedioxythiophene) : Poly(styrene sulfonate) (PEDOT : PSS). PEDTO : PSS solution is mixed with AgNWs or spin-coated on the AgNW film. Compared with AgNW film only, PEDOT : PSS film only, and polymer-mixed AgNW films, the AgNW/polymer bilayer films exhibit much better surface roughness and stretchability. It is found that spray-coating of AgNWs on uncured PDMS and spin-coating of PEDOT : PSS solution on the AgNW films enhance the surface roughness of electrodes. Such a bilayer structure also provides a stable resistance under tensile strain due to the fact that each layer acts as a detour route for carriers. With this structure, we have obtained the peak-to-peak roughness ($R_{pv}$) as low as 76.8nm and a moderate increase of sheet resistance (from $10{\Omega}/{\Box}$ under 0% strain to $30{\Omega}/{\Box}$ under 40% strain).

• 마이크로전자및패키징학회지
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• 제25권4호
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• pp.129-135
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• 2018

신축성 기판은 신축성 전자소자의 신축성, 공정성, 내구성을 결정하는 매우 중요한 소재로서 신축성 전자소자를 개발함에 있어서 우선적으로 고려해야 된다. 특히 현재 사용되는 신축성 기판은 히스테리시스가 존재하여 센서 및 기타 응용에 많은 어려움이 있다. 본 연구에서는 신축성 소재 기판으로 사용되는 PDMS와 Ecoflex를 혼합한 PDMS-Ecoflex 하이브리드 신축성 기판을 제작하여 신축성과 히스테리시스 특성을 향상하고자 하였다. 인장 시험을 통하여 신축성 하이브리드 기판의 기계적 거동을 관찰하였으며, 투과도 측정을 통하여 투과도를 평가하였다. Ecoflex의 함량이 증가할수록 하이브리드 신축성 기판은 더 유연해지며, 탄성계수는 감소한다. 또한 PDMS 기판은 270% 변형률에서 파단이 발생한 반면, PDMS-Ecoflex 하이브리드 기판은 500%의 변형률까지 파단되지 않으며 우수한 신축성을 갖는 것을 알 수 있었다. 반복 인장시험에서 PDMS와 Ecoflex의 혼합비를 2:1로 제작된 기판은 히스테리시스가 발생하였다. 반면 1:1의 혼합비로 제작된 기판의 경우 50%, 100%의 변형률에서는 히스테리시스가 발생하지 않았다. 결론적으로 500% 이상의 신축성을 갖으면서 히스테리시스가 없은 기판을 제작하였다. 기판의 혼합비에 따른 광투과도 측정 결과, Ecoflex 기판의 투과도는 68.6% 이였으나, PDMS-Ecoflex 함량이 2:1, 1:1인 하이브리드 기판의 경우, 각각 78.6%, 75.4%의 투과율을 보이며, 향후 투명 신축성 기판으로서 개발 가능성을 보여주었다.