• 한국조명전기설비학회:학술대회논문집
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• 한국조명전기설비학회 1999년도 학술대회논문집-국제 전기방전 및 플라즈마 심포지엄 Proceedings of 1999 KIIEE Annual Conference-International Symposium of Electrical Discharge and Plasma
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• pp.40-45
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• 1999

The effect of the addition of helium, neon, argon and xenon on the production of negative hydrogen ions has been studied in a magnetically confined dc filament discharge. The addition of helium and neon produced effects similar to an equivalent increase in hydrogen pressure. However, the addition of argon and low fractions of xenon produced significant increases in the negative ion density for hydrogen at pressures around 1 mTorr. The addition of argon and xenon, by increasing electron density and decreasing electron temperature, achieved conditions closer to optimum for negative ion production. The largest enhancement of negative hydrogen ion density occurred with the addition of argon; it is suggested that this is due to a resonant energy exchange between excited argon atoms and hydrogen molecules.

• Advances in concrete construction
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• 제12권6호
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• pp.461-467
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• 2021

Polyethylene-terephthalate (PET) from bottle waste and linear low-density polyethylene (LLDPE) from barrels and tanks waste are widely available and need to be recycled. Recycling them in concrete and mortar is an alternative solution for their disposal. In this study various quantities of sand (5%, 10%, 15% and 20%) were substituted by powder from LLDPE waste. In addition, PET waste fibers (corrugated, straight) were added to the mortar with different percentages (0.5%, 1%, 1.5% and 2%) of cement mass. This paper evaluate the mechanical and physical properties of the composites in fresh (workability, air content and density) and hardened state (compressive and flexural strength, water absorption and total shrinkage). From the experimental results, it can be concluded that the strengthening in tensile of the mortar with plastic waste corrugated fibers is improved. Other important results are that the water absorption and the density rate are less than that of the ordinary mortar.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2002년도 가을 학술발표회 논문집
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• pp.561-568
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• 2002

PFA(Paper Fly Ash) are reclaimed mainly or used in cement industry field as mixture agent in terms of materials recycling. Recently, research for recycling PFA as embankment materials or soil stabilization agent are undergoing in geotechnical engineering field. In this study, physical characteristics of PFA stabilization agent-soil admixtures are examined in change of water content, void ratio, consistency, grain distribution, specific gravity and density. Futhermore, the physical characteristics are compared with unconfined strength as engineering characteristics. Test results showed that unconfined strength and density are increased with increasing of PFA stabilization agent mixed ratio. On the other hand, specific gravity, void ratio and water content are decreased with increasing of PFA stabilization agent mixed ratio. It would be concluded that natural high water content ratio weak soil could be highly improved engineering and physical characteristics with PFA stabilization agent

• 한국전문물리치료학회지
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• 제22권1호
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• pp.79-92
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• 2015

The effects of Proprioceptive Neuromuscular Facilitation (PNF) and elastic band exercise on the physical functions and blood lipids of obese elderly women were investigated. The experimental group ($n_1=16$) patients underwent PNF for 12 weeks, and the control group ($n_2=15$) patients performed elastic band exercises. SPSS 21.0 was used to compute the means and standard deviations. After the 12-week PNF, both the experimental and control groups showed statistically significant differences in the physical functions (cardiovascular endurance, strength of the lower extremity, muscular endurance, flexibility, balance, and agility) (p<.05), but the difference in the experimental group was more significant than that in the control group (p<.05). In terms of the changes in the blood lipid levels (total cholesterol, triglycerides, high-density lipoprotein, and low-density lipoprotein), the experimental group showed significant changes (p<.05). In conclusion, PNF was confirmed as more effective than elastic band exercise in improving the physical functions and blood lipid levels of obese elderly women.

• The Journal of Korean Physical Therapy
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• 제22권3호
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• pp.17-21
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• 2010

Purpose: This study was designed to investigate possibilities for quantitative analysis using the electromyography and sonography. For better understanding, we evaluated the correlation between the pressure pain threshold and sonography, spontaneous electrical activity in trigger points located in the upper trapezius muscle. Methods: Thirty three active subjects volunteered to participate in this study (n=33). They had a palpable taut band, exquisite spot tenderness of a nodule in a taut band, spontaneous pain, referred pain, jump sign, local twitch response, and a painful limit to full stretch range of motion. We measured Pressure pain threshold, density, white area index, root mean square, and reaction. Pearson’s correlation coefficient was calculated to estimate the relationship between the pressure pain threshold and other variables including density, white area index, root mean square, and reaction time. Results: There were significant correlations between pressure pain threshold and density (r=-0.75, p<0.01), and between pressure pain threshold and white area index (r=-0.74, p<0.01). A significant correlations between pressure pain threshold and root mean square (r=-0.59, p<0.01). The significant correlation was found between pressure pain threshold and reaction time (r=-0.64, p<0.01). Conclusion: These should indicate whether quantitative analysis can be done using the characteristics of electromyography and sonography.

• Carbon letters
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• 제14권1호
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• pp.40-44
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• 2013

The bipolar plate is the most important and most costly component of proton exchange membrane fuel cells. The development of a suitable low density bipolar plate is scientifically and technically challenging due to the need to maintain high electrical conductivity and mechanical properties. Here, bipolar plates were developed from different particle sizes of natural and expanded graphite with phenolic resin as a polymeric matrix. It was observed that the particle size of the reinforcement significantly influences the mechanical and electrical properties of a composite bipolar plate. The composite bipolar plate based on expanded graphite gives the desired mechanical and electrical properties as per the US Department of Energy target, with a bulk density of 1.55 $g.cm^{-3}$ as compared to that of ~1.87 $g.cm^{-3}$ for a composite plate based on natural graphite (NG). Although the bulk density of the expanded-graphite-based composite plate is ~20% less than that of the NG-based plate, the I-V performance of the expanded graphite plate is superior to that of the NG plate as a consequence of the higher conductivity. The expanded graphite plate can thus be used as an electromagnetic interference shielding material.

• 폴리머
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• 제31권1호
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• pp.25-30
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• 2007

재활용 고밀도 폴리에틸렌(HDPE)에 Perbutyl peroxide(PBP)를 첨가하여 반응 용융가공에 의한 가교 특성 및 물성 변화를 살펴보았다. 그 결과, 재활용 HDPE에 포함되어 있는 다양한 이물질의 성분을 EDS를 이용하여 분석하였으며 수지의 재활용 시 포함된 유, 무기물이 가교 반응에 영향을 미침을 확인하였다. 또한 물성 측정을 통해 재활용 가교 HDPE가 신재 HDPE와 비교하여 낮은 밀도, 용융엔탈피 그리고 높은 용융점도를 가짐으로 보아 상대적으로 신재 가교 HDPE에 비하여 가교가 더 잘 일어남을 알 수 있으며 이러한 재활용 HDPE의 가교 특성은 가교에 의한 재환용 HDPE의 기계적 물성 증가에 기여함을 확인하였다.

• Composites Research
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• 제18권6호
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• pp.34-39
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• 2005

본 연구에서는 방탄재료로 활용 가능할 것으로 예상되는 여러 구조용 세라믹스의 물리기계적 물성과 방탄물성과의 상호연관성을 분석하였다. 물리기계적 물성을 측정한 후 30mm 고체추진포에서 10.7의 L/D비를 갖는 텅스텐 긴 관통자를 비행시켜 운동에너지(KE)탄에 대한 방탄물성을 측정하였으며, K215 자탄을 기폭시켜 성형작약(HEAT)탄에 대한 방탄물성을 측정하였다. 영률/밀도비, 경도/밀도비 및 꺽임강도/밀도비가 증가할수록 방탄물성이 대체적으로 증가하는 경향을 보였으며, 특히 HEL(Hugoniot Elastic Limit)/밀도비가 증가함에 따라 KE탄에 대한 방탄물성이 선형적으로 증가하는 현상을 나타내었다.

• Journal of the Korean Wood Science and Technology
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• 제33권2호통권130호
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• pp.40-55
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• 2005

This study was carried out to discuss the feasibility of wood and plastic wastes as the raw materials for wood particle-plastic composites. For this purpose, composites were manufactured from coarse and fine wood particles and polypropylene fibers by nonwoven web process. And the effect of wood particle size on the performance of the composites were analyzed according to ASTM D 1037-93. In the physical properties of composites, water absorption decreased with the increase of target density and polypropylene fiber content. And the composites with fine wood particles appeared to have slightly lower water absorption than those with coarse wood particles. Thickness swelling did not vary significantly with the increase of target density but increased with the increase of wood particle content. And the composites with fine wood particles were significantly lower in thickness swelling than those with coarse wood particles. In the mechanical properties of composites, dry and wet MOR showed the increasing tendency with the increase of polypropylene fiber content and target density. Dry and wet MOE showed the increasing tendency with the increase of target density but only wet MOE exhibited the increasing tendency with the increase of polypropylene fiber content. Composites with fine wood particles appeared to be generally higher in wet MOR and MOE than those with coarse wood particles. In conclusion, composites with fine wood particles showed generally higher performance than those with coarse ones. Also, composites were significantly superior to control particleboards in the performance, especially in water absorption and thickness swelling.

• 한국전기전자재료학회논문지
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• 제31권1호
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• pp.40-43
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• 2018

Various Ni-doped carbon (C : Ni) thin films were fabricated using different Ni target power densities by unbalanced magnetron sputtering (UBM). The effects of target power density on the structural, physical, surface, and electrical properties of C : Ni films were investigated. The UBM C : Ni thin films exhibited uniformly smooth surfaces. The rms surface roughness and friction coefficient values of the C : Ni films decreased with the increase in target power density. The physical properties of the films such as hardness and elastic moduli increased while their electrical properties such as resistivity decreased with the increase in the target power density. These results show that an increase of the power density leads to an increase in the proportion of Ni and nanocrystallization of the amorphous carbon film; this contributes to the changes observed in the physical and electrical characteristics.