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Rheological Characterization of Aqueous Poly(Ethylene Oxide) Solutions(III) - Determination of Discrete Relaxation Spectrum and Relaxation Modulus from Linear Viscoelastic Functions - (폴리에틸렌옥사이드 수용액의 유변학적 특성 평가(III);선형점탄성 함수로부터 이산완화 스펙트럼 및 완화탄성률 결점)

  • 송기원;노동현;장갑식
    • Textile Science and Engineering
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    • v.35 no.9
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    • pp.550-561
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    • 1998
  • Some methods have been evaluated to predict the stress relaxation behavior of concentrated polymer solutions from their linear viscoelastic functions. The linear viscoelastic properties and the linear relaxation modulus of concentrated aqueous poly(ethylene oxide) (PEO) solutions were measured with a Rheometrics Fluids Spectrometer (RFS II) and an Advanced Rheometric Expansion System (ARES-200 FRTN1). The discrete relaxation spectrum (DRS) was determined using three methods, namely, a linear regression, without and with regularization, and a nonlinear regression of the dynamic storage and loss moduli. The effects of several factors on the fitting procedure to determine the DRS and of the molecular weight and solution concentration on the relaxation behavior were discussed. Further, the experimentally measured retaxation modulus G(t) was compared with the results obtained from the two kinds of calculation methods. The first kind is to calculate C(t) from the DRS using the generalized Maxwell model, and the second one is a direct conversion of the dynamic moduli using the Fourier transform. Finally, the reliability of the DRS determination and G(t) calculation methods was examined by comparing the experimental storage and loss moduli with those back-calculated from the DRS and calculated from the measured G(t). Main results obtained from this study can be summarized as follows : (1) All three methods for the determination of DRS from dynamic data give similar values of the relaxation strength of modulus for a given value of each relaxation time, even though the number of relaxation times becomes different to avoid a mathematically ill-posed problem. (2) For highly concentrated polymer solutions, both linear and nonlinear regression methods have a restriction on the number of relaxation times. On the other hand, a linear regression method with regularization has a larger number of relaxation times, and consequently, shows a more distinct shape of the relaxation spectrum than the other regression methods. (3) The G(t) calculated from the DRS and by a direct conversion of the dynamic moduli is in good agreement with the experimentally measured G(t). Therefore, the C(t) calculated from the linear viscoelastic functions using the two kinds of methods provides a sufficient information to predict the actual stress relaxation behavior. (4) The storage and loss moduli back-calculated from the DRS and calculated from the measured G(t) coincide well with the experimentally measured data. It can, therefore, be concluded that the DRS determination as well as G(t) calculation methods adopted in this study have a considerably high reliability.

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Exploration of suitable rice cultivars for close mixed-planting with upland-adapted cereal crop

  • Shinohara, Nodoka;Shimamoto, Hitoshi;Kawato, Yoshimasa;Wanga, Maliata A.;Hirooka, Yoshihiro;Yamane, Koji;Iijima, Morio
    • Proceedings of the Korean Society of Crop Science Conference
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    • pp.304-304
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    • 2017
  • In semi-arid countries such as Namibia, the flooding unexpectedly happens in a rainy season, causing losses in the yield of upland-adapted cereal crop. In flooding conditions, rice roots sequentially form aerenchyma and a barrier to radial oxygen loss (ROL), and oxygen is released into the rhizosphere near the root tips. Iijima et al. (2016) and Awala et al. (2016) reported that close mixed-planting with rice can mitigate the flood stress of co-growing upland-adapted cereal crop by modifying their rhizosphere microenvironments via the oxygen released from the rice roots. Moreover, by using the model system of hydroponic culture, it was confirmed that oxygen from rice roots was transferred to co-growing upland-adapted cereal crop in close mixed planting system (Kawato et al., 2016). However, it is not sure whether the ability of oxygen release varies among rice cultivars, because Kawato et al. (2016) used only one japonica cultivar, Nipponbare (Oryza sativa). The objective of this study was to compare the ability of oxygen release in rhizosphere among rice cultivars. The experiment was conducted in a climate chamber in Kindai University. We used 10 rice cultivars from three different rice species (O. sativa (var. japonica (2), var. indica (3)), Oryza glaberrima Steud. (2) and their interspecific progenies (3)) to compare the ability of oxygen release from the roots. According to the method by Kawato et al. (2016), the dissolved oxygen concentration of phase I (with shoot) and phase II (without shoot) were measured by a fiber optic oxygen-sensing probe. The oxygen released from rice roots was calculated from the difference of the measurements between phase I and phase II. The result in this study indicated that all of the rice cultivars released oxygen from their roots, and the amount of released oxygen was significantly correlated with the above-ground biomass (r = 0.710). The ability of oxygen release (the amount of the oxygen release per fresh root weight) of indica cultivars (O. sativa) tended to be higher as compared with the other cultivars. On the other hand, that of African rice (O. glaberrima) and the interspecific progenies tended to be lower. These results suggested that the ability of oxygen release widely varies among rice cultivars, and some of indica cultivars (O. sativa) may be suitable for close mixed-planting to mitigate flood stress of upland-adapted cereal crop.

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Quality and Nutrition Labeling Study of Domestic Fruit (Plum) (국내산 청과물 (자두)의 품질 영양표시에 관한 연구)

  • Jung, Jun-Gyo;Yu, Yeon;Kim, Suk-Kyung;Lee, Hye-Ryun;Choi, Jong-Uck;Lee, Sang-Han;Ahn, Hong;Chung, Shin-Kyo
    • Korean Journal of Food Preservation
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    • v.13 no.6
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    • pp.669-674
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    • 2006
  • In order to develop a model on the quality and nutrition label of Korean fruit plum, we first examined the quality and nutritional characteristics of Korean Plum, ChooHee. The contents of moisture, crude protein, crude fat, crude fiber, crude ash and N-free extinct were 92% 0.74% 0.64% 1.65%, 0.32% 4.29% respectively. Thus the total calorie of the sample was 32 kcal/100 g. The content of sugar, acidity and Vitamin C were $33{\pm}0.85 Bx^{\circ}$, $1.08{\pm}0.12%$ and $7.037{\pm}0.317mg%$ respectively. The principle minerals were S, K, Ca, Na, and Mg. Major free sugars were fructose, glucose and sucrose and major organic acid were succinic acid, malic acid and citric acid. The difference of contents of total phenols between peel and flesh pare were considerable. The total phenolic contents of whole fruit were $75.55{\pm}0.73mg%$. On the above results, the quality and nutrition label of Korean plum were developed in the first time. We expect that this study on labeling could play an important role to the quality control and marketing of Korean agricultural products.

Geotechnical Engineering Progress with the Incheon Bridge Project

  • Cho, Sung-Min
    • Proceedings of the Korean Geotechical Society Conference
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    • pp.133-144
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    • 2009
  • Incheon Bridge, 18.4 km long sea-crossing bridge, will be opened to the traffic in October 2009 and this will be the new landmark of the gearing up north-east Asia as well as the largest & longest bridge of Korea. Incheon Bridge is the integrated set of several special featured bridges including a magnificent cable-stayed girder bridge which has a main span of 800 m width to cross the navigation channel in and out of the Port of Incheon. Incheon Bridge is making an epoch of long-span bridge designs thanks to the fully application of the AASHTO LRFD (load & resistance factor design) to both the superstructures and the substructures. A state-of-the-art of the geotechnologies which were applied to the Incheon Bridge construction project is introduced. The most Large-diameter drilled shafts were penetrated into the bedrock to support the colossal superstructures. The bearing capacity and deformational characteristics of the foundations were verified through the world's largest static pile load test. 8 full-scale pilot piles were tested in both offshore site and onshore area prior to the commencement of constructions. Compressible load beyond 30,000 tonf pressed a single 3 m diameter foundation pile by means of bi-directional loading method including the Osterberg cell techniques. Detailed site investigation to characterize the subsurface properties had been carried out. Geotextile tubes, tied sheet pile walls, and trestles were utilized to overcome the very large tidal difference between ebb and flow at the foreshore site. 44 circular-cell type dolphins surround the piers near the navigation channel to protect the bridge against the collision with aberrant vessels. Each dolphin structure consists of the flat sheet piled wall and infilled aggregates to absorb the collision impact. Geo-centrifugal tests were performed to evaluate the behavior of the dolphin in the seabed and to verify the numerical model for the design. Rip-rap embankments on the seabed are expected to prevent the scouring of the foundation. Prefabricated vertical drains, sand compaction piles, deep cement mixings, horizontal natural-fiber drains, and other subsidiary methods were used to improve the soft ground for the site of abutments, toll plazas, and access roads. Light-weight backfill using EPS blocks helps to reduce the earth pressure behind the abutment on the soft ground. Some kinds of reinforced earth like as MSE using geosynthetics were utilized for the ring wall of the abutment. Soil steel bridges made of corrugated steel plates and engineered backfills were constructed for the open-cut tunnel and the culvert. Diverse experiences of advanced designs and constructions from the Incheon Bridge project have been propagated by relevant engineers and it is strongly expected that significant achievements in geotechnical engineering through this project will contribute to the national development of the longspan bridge technologies remarkably.

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Experimental Assessment of Hemostatic Agents: Comparison with New Developed Chitosan-Based Material (신개발 키토산 제재의 지혈 효과에 대한 비교)

  • Cho, Young-Kyoo;Lee, Sang-Yun;Kim, Tae-Jung;Lim, Hyun-Ju;Oh, Eun-Jung;Lee, Soo-Bok;Choi, Kang-Young;Yang, Jung-Dug;Cho, Byung-Chae;Chung, Ho-Yun
    • Archives of Plastic Surgery
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    • v.38 no.4
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    • pp.369-375
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    • 2011
  • Purpose: Many hemostatic agents and dressings have been tested with variable degree of success. Chitosan has a positive charge, it attracts red blood cells, which have a negative charge. Our goal is to test the efficacy of new developed chitosan-based hemostatic materials in providing durable hemostasis in a high-flow arterial wound model. Methods: We compared each group with SD rats motality tests and in vitro blood compatibility test by blood clotting index (BCI). We devided the SD rats into 6 groups (N =15) by type of hemostatic agents. A: 100% nonwoven chitosan (degree of the deacetylation: 90%). B: 50% N-acetylation on nonwoven of chitosan gel (degree of the deacetylation: 50%). C: 60% N-acetylation on nonwoven of chitosan ge (degree of the deacetylation: 40%)l. D: Cutanplast$^{(R)}$. E: HemCon$^{(R)}$ F: Gauze. In vivo test, a proximal arterial injury was created in unilateral femoral arteries of 90 anesthetized SD rats. Each materials was made same size and thickness then applied to the injury site for 3 minutes. In vitro test, we compared each group with BCI in human blood. Results: In vivo test, group A showed lower motality rate of 46% than any other groups, Group B and C showed lower motality rate of 60% than group D and E's motality rate of 66%. In vitro test, BCI of group A ($30.6{\pm}1.2$) and B ($29.3{\pm}1.0$) were showed nearly about group D ($29.1{\pm}1.8$) and E ($27.4{\pm}1.6$). Group C ($37.1{\pm}2.0$) showed higher BCI than group A and B, it means group C decreased blood clotting. Conclusion: In conclusion, this study suggests a newly developed chitosan-based hemostatic materials induced durable hemostasis and increased blood clotting, and are considered as effective biologic hemostatic agents.

A Study on User Interface of the Broadband Access Network Operation Support System (광대역 가입자망 운용관리를 위한 그래픽 유저 인터페이스(GUI) 개발에 관한 연구)

  • 장은상;이종호;임현민;하동석
    • Archives of design research
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    • v.12 no.4
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    • pp.61-68
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    • 1999
  • Most of the time, developers spend their energy to analyze the main function of the system or make source codes. As a result, they can not consider user interface on their own system and this is true in most programmer's world. But we want to consider the design concept in developing mechanism. In this case we have to upgrade the legacy system which maintaining the transmission system using the copper cables, and add the transmission system using the optical fiber cables. Therefore we design the user interface make easy for end users who are using the maintaining system on copper cables not to confuse the new system which include optical fibers. Especially, we are consider the developing model of design policy and real user to make easy to use new system. In this paper we will describe the instance to adapt the design concept on Broadband Access Network Operation Support System.

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Induction of Muscle Atrophy by Dexamethasone and Hydrogen Peroxide in Differentiated C2C12 Myotubes (C2C12 근관세포에서 dexamethasone 및 hydrogen peroxide에 의한 근위축 유도)

  • Park, Cheol;Jeong, Jin-Woo;Choi, Yung Hyun
    • Journal of Life Science
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    • v.27 no.12
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    • pp.1479-1485
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    • 2017
  • Muscle atrophy due to aging, starvation, and various chronic diseases leads to a decrease in muscle fiber area and density due to reduced muscle protein synthesis and increased protein breakdown. This study investigated the effect of dexamethasone and hydrogen peroxide on the induction of muscle atrophy and expression of atrophy-related genes in differentiated C2C12 myotubes. C2C12 myoblasts were differentiated into myotubes in differentiation medium. During myoblast differentiation, muscle-specific transcription factors, such as myogenin, and MyoD expression increased. Differentiated C2C12 myotubes exposed to noncytotoxic levels of dexamethasone and hydrogen peroxide showed a decrease in myotube diameter, which was associated with up-regulation of muscle-specific ubiquitin ligases, such as muscle atrophy F-box (MAFbx)/atrogin-1 and muscle RING finger-1 (MuRF1), and down-regulation of myogenin and MyoD. These results demonstrated that dexamethasone and hydrogen peroxide induced atrophy through regulation of muscle-specific ubiquitin ligases and muscle-specific transcription factors in C2C12 myotubes. In this study, we confirmed the process of differentiation of C2C12 myoblasts into myotubes in in vitro experiments in the presence of atrophy. This muscle atrophy model of C2C12 cells induced by dexamethasone or hydrogen peroxide seems suited to studies of the mechanism of muscle atrophy suppression and to exploit the experiment for excavating new muscle atrophy.

The Effect of Ultrasound Treatment on Regeneration Nerve and Muscle on Injured Peripheral Nerve of Rats Model (말초신경 손상 백서모델에서 초음파 치료의 신경 및 근육 재생효과)

  • Cheong, Mee-Sun;Kim, Kyoung-Yoon
    • The Journal of Korean Physical Therapy
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    • v.17 no.4
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    • pp.589-600
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    • 2005
  • The purposes of this study is to discuss and analyze the effect on the recovery from cut in sciatic nerve. This study used 9 weeks male rats of Sprague-Dawley family. Rat in groups 4 were treated with pulsed therapeutic ultrasound for 3 minutes. 3 times weekly at 3MHz respectively (intensity; $0.2W/cm^2,\;0.5W/Cm^2,\;10W/cm^2$); rat in group 1 received placebo ultrasound. In addition, changes of serum aspartate amino-transferase(AST) and creatine phosphokinase(CPK) levels were also demonstrated with diameter of individual muscle fasciculate and number of muscle fiber in each of three types of muscles located in gastrocnemius, soles. The results of comparing the changes in groups are as follows; 1. We found out that hypertrophic epineurium was present in sciatic nerve injured ultrasound treatment of groups. 2. In the gastrocnemius morphological investigation of the group I (control group), severe muscle atrophy were observed at the 7th days of the sciatic nerve injury. however, muscle atrophy of the group IV ($1.0W/cm^2$) were slightly recovered at the 14th days after treatment ultrasound. At the 28th days, muscular fibers were formed in polygon and were significantly recovered. 3. C-fos immunoreactive of the group II ($0.2W/cm^2$), III ($0.5W/cm^2$) were remarkably increased at the 1th day after treatment of ultrasound. Group IV were markedly deceased. 4. Brain-Derived Neurotrophic Factor(BDNF) immunoreactive of the group II, III were increased after 7 days of the sciatic nerve injury. Group IV were markedly increased from 14th days to 28th days after treatment of ultrasound. 5. A significant increase of serum AST levels were demonstrated in control group. However, serum AST levels of massage groups were significantly decreased compared to that of control group in followed order ; ($0.2W/cm^2<0.5W/cm^2<1.0W/cm^2$). 6. A significant increase of serum CK levels were demonstrated in control of group. However, serum CK levels of massage groups were significantly decreased compared to that of control group in followed order ; ($0.2W/cm^2<0.5W/cm^2<1.0W/cm^2$). The above results suggest that ultrasound treatment after peripheral nerve injury might reduce noxious stimuli, facilitate nerve recovery and effective in the functional improvement delaying muscle atrophy or degeneration.

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The Experimental Study on the Absorbed Energy of Carbon/Epoxy Composite Laminated Panel Subjected to High-velocity Impact (고속 충격을 받는 Carbon/Epoxy 복합재 적층판의 흡수 에너지 예측에 대한 실험적 고찰)

  • Cho, Hyun-Jun;Kim, In-Gul;Lee, Seokje;Woo, Kyeongsik;Kim, Jong-Heon
    • Composites Research
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    • v.26 no.3
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    • pp.175-181
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    • 2013
  • The evaluation and prediction for the absorbed energy, residual velocity, and impact damage are the key things to characterize the impact behavior of composite laminated panel subjected to high-velocity impact. In this paper, the method to predict the residual velocity and the absorbed energy of Carbon/Epoxy laminated panel subjected to high velocity impact are proposed and examined by using quasi-static perforation test and high-velocity impact test. Total absorbed energy of specimen due to the high-velocity impact can be grouped with static energy and kinetic energy. The static energy are consisted of energy due to the failure of the fiber and matrix and static elastic energy, which are related to the quasi-static perforation energy. The kinetic energy are consisted of kinetic energy of moving part of specimen, which are modelled by three modified kinetic model. The high-velocity impact test were conducted by using air gun impact facility and compared with the predicted values. The damage area of specimen were examined by C-scan image. In the high initial impact velocity above the ballistic limit, both the static energy and the kinetic energy are known to be the major contribution of the total absorbed energy.

Physiological Characteristics and Yield of Onion Affected by Rapid Temperature Changes (급변온도 변이에 따른 양파의 생리적 특성 및 수량 변화)

  • Lee, Hyeong-Jin;Han, Hyo-Shim;Chon, Sang-Uk;Kim, Dong-Kwan;Kwon, Hyun Sook;Lee, Kyung Dong
    • Korean Journal of Environmental Agriculture
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    • v.33 no.4
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    • pp.364-371
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    • 2014
  • BACKGROUND: To evaluate the impact of rapid temperature change at spring and the early summer seasons in climate change, we have investigated the physiological response and yield of onion in a greenhouse with thermostat control system. METHODS AND RESULTS: Seedlings of onion(cv. Sunshine) were planted on October 30, 2012 and harvested on May 30, 2013. The used treatments(March-April-May) for a rapid temperature change were T0(control): $6.0-10.4-17.2^{\circ}C$, T1: $6.0-5.4(-5)-17.2^{\circ}C$, T2: $6.0-10.4-22.2(+5)^{\circ}C$ and T3: $6.0-5.4(-5)-22.2(+5)^{\circ}C$. Total yields of bulb within the temperature change as high temperature treatment T2 and control treatment T0 were increased significantly(p<0.05), as compared to the low temperature treatment T1. Low temperature conditions significantly (p<0.05) reduced plant height, SPAD reading, crude protein and fiber etc., as compared to the TO and T2. CONCLUSION: The rapid temperature changes were highly affected by low temperature than high temperature. These results suggest that rapid climate change of future could need systematic standard model for physiological characteristics and yields of onion.