• Polymer(Korea)
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• v.32 no.3
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• pp.230-238
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• 2008

The thermal and optical properties of cellobiose octa(cholestryloxycarbonyl)alkanoates CCCBn, $n=2{\sim}8$,10, the number of methylene units in the spacer) were investigated. All the samples formed monotropic cholesteric phases with left-handed helical structures. CCBn with n=2 or 10, in contrast with CCBn with $3{\leq}n{\leq}8$, did not display reflection colors over the full cholesteric range, suggesting that the helical twisting power of the cholesteryl group highly depends on the length of the spacer connecting the cholesteryl group to the cellobiose chain. The isotropic-cholestropic transition ($T_{ic}$) and glass transition temperatures decreased with increasing n and showed no odd-even effect. The transition entropy at $T_{ic}$ increased with increasing n from 2 up 6, but at n=7 it drops significantly and then increased again with increasing n from 8 to 10. The sharp change at n=7 may be attributed to a difference in arrangement of the side groups. The thermal stability and degree of order in the mesophase and the temperature dependence of the optical pitch observed for CCBn were significantly different from those reported for the cellulose tri(cholesteryloxycarbonyl)alkanoates and glucose penta(cholesteryloxycarbonyl)alkanoates. The results were discussed in terms of the differences in the degree of polymerization, the number of the mesogenic units per mole-glucose unit, and the conformation of the molecules.

• The Journal of Natural Sciences
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• v.6 no.1
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• pp.5-39
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• 1993

The Blue-green algae collected from whole coasts of Korea were investigated morphotaxonomically in order to list up Korean marine Cyanophyta and clarify their taxnomic position. As a result, 36 species, 20 genus, 6 families belonging to 3 orders were identified. Among these, 14 species were recorded for the first time in Korea. They are Chroococcus minutus (K$\"{u}$tzing) N$\"{a}$geli, Merismopedia punctata Meyen, Microcystis ichtyoblabe K$\"{u}$zing, Dermocarpa leibleiniae (Reinsch) Born. et Thur., Hydrocoleum confluens (Setchell et Gardner) Drouet, Lyngbya sordida (Zanard.) Gomont, Phormidium forveolarum (Mont.) Gomont, Phormidium hansgieri Schmidle, Skujaella hildebrandtii (Gomont.) de Toni, Sphaeronema lithophila (Ercegovic) Umezaki, Spirulina tenerrima K$\"{u}$tzing, Hormothamnion enteromorphoides Grunow, Michrochaete aeruginea Batters, Michrochaete grisea Thuret ex Born. et flah.. Using the phase contrast microscope and the Nomarski interference micrope, we made photomicrographs of minute blue green algae. The cellular inclusions especially PHB(poly-$\SS$-hydroxy-butyrate) granules of the blue-green algae identified were investigated. The species clearly characteriged to have PHB granule were Lyngbya confervoides, L. semiplena, Phormidium corium, Sirocoleum kurzii, Hormothamnion enteromorphoides and Calothrix crustacea. These result would be fundamental data for estabilishing phylogenetic system of blue-green algae based on physio-biochemical characteristics in future.

• Korean Journal of Microbiology
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• v.50 no.4
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• pp.360-367
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• 2014

Candida albicans is an opportunistic and the most prevalent fungal pathogen that can cause superficial and systemic infections in immunocompromised patients. C. albicans can promote the transition from budding yeast to filamentous form, generating biofilms. Infections associated with C. albicans biofilms are frequently resistant to conventional antifungal therapy. Therefore, the development of more effective antifungal drugs related with biofilm formation is required urgently. The roots of Rheum undulatum have been used for medicinal purposes in Korea and China traditionally. The aim of present study was to evaluate the effect of R. undulatum extract upon preformed biofilms of 12 clinical C. albicans isolates and the antifungal activities. Its effect on preformed biofilms was evaluated using XTT reduction assay, and metabolic activity of all tested strains was reduced significantly ($49.4{\pm}6.0%$) at 0.098 mg/ml R. undulatum. The R. undulatum extract blocked the adhesion of C. albicans biofilms to polystyrene surfaces, and damaged the cell membrane integrity of C. albicans which was analyzed by CFDA, AM, and propidium iodide double staining. It caused cell lysis which was observed by Confocal laser scanning and phase contrast microscope after propidium iodide and neutral red staining, respectively. Membrane permeability was changed as evidenced by crystal violet uptake. The data suggest that R. undulatum inhibits biofilm formation by C. albicans, which can be associated with the damage of the cell membrane integrity, the changes in the membrane permeability and the cell lysis of C. albicans.

• Physical Therapy Korea
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• v.4 no.3
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• pp.17-33
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• 1997

The objective of this study was to identify pulmonary functional variations in relation to postural changes, lapse after changing position, and the use of abdominal band in the cervical cord injured. The subjects of this study were 19 quadriplegic patients who had been admitted to the department of the Rehabilitation Hospital, College of Medicine, Yousei University, from April, 1997 through May 3, 1997. A spiroanalyzer was used to measure pulmonary function in supine, standing, time after changing position, and recording to the position, application method, and tightness of the abdominal band. The data were analyzed by the repeated measure one-way ANOVA, and Wilcoxon signed rank test. The findings were as follows: 1. All phase of the patients' pulmonary function improved significantly in supine posture in contrast to standing (vital capacity by $0.46{\ell}$ and expiratory reserve volume by $0.09{\ell}$). 2. The longer the time lapsed from supine posture to standing, the patient's expiratory reserve volume, maximum ventilation volume, vital capacity, and forced expiratory volume increased. 3. When the patient lay in supine position, the maximum ventilation volume, vital capacity, and the forced vital capacity increased then the center line of the abdominal band was placed along iliac crest; on the other hand, when the patient was standing, placing the bottom line of the abdominal band along iliac crest increased the maximum ventilation volume, vital capacity, and forced expiratory volume. 4. In placing the abdominal band in the patients, leaving space between the top and bottom lines of the band helped increased in maximum ventilation volume, vital capacity, and forced vital capacity for patient in supine as well as in standing. 5. When placing the abdominal band to patients in supine posture, reducing the length of the band by 2.5% along the patient's waist line increased the patients' vital capacity, while reducing the length by 10% to patients in standing increased the maximum ventilation volume. The abdominal band should be placed in such a way that the bottom part of the band should be more tightly fastened while leaving enough room for a hand to be placed in between the body and the band for the top part of the hand. It should also be noted that in a supine position, the bottom line of the band should be placed along the iliac crest, while in standing, the center line should be placed along the iliac crest. The length of the band should also be reduced by 2.5% of the waist line in supine position, and in standing, the length should be reduced by 10%. It should also be noted that the pulmonary function of the patients should be measured at least 10 minutes after one position change.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.18 no.9
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• pp.2109-2116
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• 2014

This paper presents the implementation and design of the advanced WI-FI systems with beam-forming antenna that radiate their power to the direction of user equipment to improve the overall throughput, contrast to the general WI-FI systems equipped with omni-antenna. The system consists of patch array antenna, DSP, FPGA, and Qualcomm's commercial chip. The beam-forming system on the FPGA utilizes the packet information from Qualcomm's commercial chip to control the phase shifters and attenuators of the patch array antenna. The PCI express interface has been used to maximize the communication speed between DSP and FPGA. The directions of arrival of users are managed using the database, and each user is distinguished by the MAC address given from the packet information. When the system wants to transmit a packet to one user, it forms beams to the direction of arrival of the corresponding user stored in the database to maximize the throughput. Directions of arrival of users are estimated using the received preamble in the packet to make its SINR as high as possible. The proposed beam-forming system was implemented using an FPGA and Qualcommm's commercial chip together. The implemented system showed considerable throughput improvement over the existing general AP system with omni-directional antenna in the multi-user communication environment.

• Restorative Dentistry and Endodontics
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• v.43 no.2
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• pp.25.1-25.10
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• 2018

Objectives: To evaluate the mechanical properties and metallurgical characteristics of the M3 Rotary and M3 Pro Gold files (United Dental). Materials and Methods: One hundred and sixty new M3 Rotary and M3 Pro Gold files (sizes 20/0.04 and 25/0.04) were used. Torque and angle of rotation at failure (n = 20) were measured according to ISO 3630-1. Cyclic fatigue resistance was tested by measuring the number of cycles to failure in an artificial stainless steel canal ($60^{\circ}$ angle of curvature and a 5-mm radius). The metallurgical characteristics were investigated by differential scanning calorimetry. Data were analyzed using analysis of variance and the Student-Newman-Keuls test. Results: Comparing the same size of the 2 different instruments, cyclic fatigue resistance was significantly higher in the M3 Pro Gold files than in the M3 Rotary files (p < 0.001). No significant difference was observed between the files in the maximum torque load, while a significantly higher angular rotation to fracture was observed for M3 Pro Gold (p < 0.05). In the DSC analysis, the M3 Pro Gold files showed one prominent peak on the heating curve and 2 prominent peaks on the cooling curve. In contrast, the M3 Rotary files showed 1 small peak on the heating curve and 1 small peak on the cooling curve. Conclusions: The M3 Pro Gold files showed greater flexibility and angular rotation than the M3 Rotary files, without decrement of their torque resistance. The superior flexibility of M3 Pro Gold files can be attributed to their martensite phase.

• Journal of Embryo Transfer
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• v.18 no.1
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• pp.51-59
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• 2003

This study was carried out to evaluate the effect of different freezing and thawing rates on the viability, motility and acrosomal changes of frozen canine spermatozoa. The ejaculated semen was extended with Tris-egg yolk buffer containing 8% glycerol and equilibrated for 60 min after cooled to 4$^{\circ}C$ for 58 min. The straws were cryopreserved gradually by slow-cooling at different distance(6, 10 and 17 cm, respectively) from the liquid nitrogen (L$N_2$) to achieve temperature rate of 3, 8.9 and 19$^{\circ}C$ /min. Thawing of the straws was performed in a water bath fur 2 min at 37$^{\circ}C$ and 55$^{\circ}C$ , respectively. The motility of frozen-thawed spermatozoa was assessed by phase-contrast microscopy. To assess their viability and acrosome content, spermatozoa were stained with a vital stain and Fluorescence conjugated lectin Pisum Savitum Agglutinin (FITC/PAS), respectively. Concentration of the ejaculated fresh semen was normal range of 3.44 $\times$ 10$^{8}$ /ml. Freezing temperature were reduced to -110, -70 and -35$^{\circ}C$, as higher distance from liquid nitrogen, 6, 10 and 17 cm, respectively. Freezing at 3$^{\circ}C$/min in distance of 17 cm from liquid nitrogen yielded better motility, viability and rate of intact acrosome than 8.9 or 19$^{\circ}C$/min and the optimal thawing was 37$^{\circ}C$ for 2 min.

• Journal of the Korean Society of Clothing and Textiles
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• v.32 no.6
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• pp.991-998
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• 2008

This study is to determine the effects of PCM concentration on the temperature changes of the air layers of a garment when the environmental temperature changes. The selected PCM was Nonadecane and coated on cotton fabrics with PCM concentrations 10%, 20%, and 30%. The temperature changes of the air layers between fabrics were measured by Human-Clothing-Environment Simulator which measure a dynamic heat transfer. After stabilizing at $34^{\circ}C$ for 1 hour, the multi layered garment system were exposed to $5^{\circ}C$ or $10^{\circ}C$ for 30 minutes and then, exposed to $34^{\circ}C$ for 30minutes. The results like following could be obtained. When the environmental temperature changed high to low, temperature of the air layer increased by heating effect of PCM. In the contrast, when the environmental temperature changed low to high, the temperature increase of the air layer was delayed because of cooling effect by PCM. Also, the more concentration of PCM, the bigger the heating effect. Cooling effect showed more clearly at PCM concentration 20%. The temperature differences of the air layers between with PCM fabrics and with non-PCM fabrics were bigger at $10^{\circ}C$ than at $5^{\circ}C$. Consequently, though PCM has influenced on the temperature of the air layer by heating and cooling effect, those effects haven't shown in all layers equally. It was shown that the effect of PCM varied according to the layer in the case of multi layered garment system and heat gain as well as heat loss in the outermost layer had to be taken into account.

• Reproductive and Developmental Biology
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• v.33 no.3
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• pp.163-169
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• 2009

Many biological systems are regulated by an intricate set of feedback loops that oscillate with a circadian rhythm of roughly 24 h. This circadian clock mediates an increase in body temperature, heart rate, blood pressure, and cortisol secretion early in the day. Recent studies have shown changes in the amplitude of the circadian clock in the hearts and livers of streptozotocin (STZ)-treated rats. It is therefore important to examine the relationships between circadian clock genes and growth factors and their effects on diabetic phenomena in animal models as well as in human patients. In this study, we sought to determine whether diurnal variation in organ development and the regulation of metabolism, including growth and development during the juvenile period in rats, exists as a mechanism for anticipating and responding to the environment. Also, we examined the relationship between changes in growth factor expression in the liver and clock-controlled protein synthesis and turnover, which are important in cellular growth. Specifically, we assessed the expression patterns of several clock genes, including Per1, Per2, Clock, Bmal1, Cry1 and Cry2 and growth factors such as insulin-like growth factor (IGF)-1 and -2 and transforming growth factor (TGF)-${\beta}1$ in rats with STZ-induced diabetes. Growth factor and clock gene expression in the liver at 1 week post-induction was clearly increased compared to the level in control rats. In contrast, the expression patterns of the genes were similar to those observed after 5 weeks in the STZ-treated rats. The increase in gene expression is likely a compensatory change in response to the obstruction of insulin function during the initial phase of induction. However, as the period of induction was extended, the expression of the compensatory genes decreased to the control level. This is likely the result of decreased insulin secretion due to the destruction of beta cells in the pancreas by STZ.

• The Korean Journal of Pesticide Science
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• v.11 no.3
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• pp.164-170
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• 2007

The concept of innate immunity in insects which refers to the first line of host defense constitutes the humoral and cellular components which are involved in recognition and actively participate in the elimination of the intruding foreign micro- or macro-organisms. Several recent studies suggest that juvenile hormone (JH) modulates the cellular immune reactions in response to pathogen. In this study, pyriproxyfen (a JH agonist as an insect growth regulator) was tested in its any inhibitory effect on the immune reactions of the beet armyworm, Spodoptera exigua. To this end, five different hemocyte morphotypes of final instar S. exigua were identified by phase contrast microscopy. Plasmatocytes and granular cells, which constitute about 90% of the total hemocyte count, were prominently distinguished based on their basophilic/acidophilic nature using Giemsa stain. The role of pyriproxyfen on the functional ability of hemocytes was analyzed using FITC-labeled Providencia vermicola for the phagocytic potential of the hemocytes. Both granular cells and plasmatocytes exhibited phagocytosis behavior. Pyriproxyfen significantly inhibited the phagocytosis of both cell types, proposing its novel action as an immunosuppressant.