• Journal of Pharmaceutical Investigation
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• 제38권4호
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• pp.229-234
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• 2008

In the present study, chitosan-glycerophosphate sodium salt solution as a thermosensitive system (TSS) was used to formulate a temperature-sensitive drug delivery system (TSDDS) containing acetaminophen (AAP). The optimized TSS was prepared by measuring gelation temperature, gelation time and rheological properties of TSS. The optimized gelation temperature and time of TSS were $36^{\circ}C$ and 100 seconds, respectively. The viscosity of TSS was also suitable for maintaining gel structure at $37.2^{\circ}C$. The release profiles of TSDDS in PBS/pH 7.4 with various apparatuses and mass loss of TSDDS were investigated. The time required to release 50% of AAP from TSDDS ($t_{50%}$) was 120 min with the formation of pore on the surfaces, which was 2 times longer than that from AAP-chitosan gel. In addition, TSDDS was degraded approximately 80% within 4 hr and then degraded slowly for 20 hrs. In conclusion, AAP-TSS (TSDDS) formulated in this study might be suitable for some specific uses such as subcutaneous injection and rectal formulation.

• International Journal of Industrial Entomology and Biomaterials
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• 제27권1호
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• pp.180-184
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• 2013

Recently, silk sericin has attracted the attention of researchers owing to its useful properties as a biomaterial including 1) good wound healing and cell activities, 2) fast gelation character, and 3) high water retention property. In the present study, silk sericin was prepared using different extraction times in hot water and the effect of extraction time on the rheological properties of sericin solutions and gels was examined. It was found that the production yield of sericin increased with extraction time. The shear viscosity of sericin solutions and gels decreased with increasing extraction time due to a decrease in sericin molecular weight. When the sericin solution transformed to a gel, the viscosity increased and the shear thinning behavior was more evident. In addition, the shear stress measurements indicated that the slip between the sericin samples and the measuring plate of the rheometer was increased by the gelation of sericin. The compression strength of sericin gel could be increased remarkably (by more than 100 fold) by preparation using the freezing and thawing method.

• Bulletin of the Korean Chemical Society
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• 제24권10호
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• pp.1485-1489
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• 2003

The gelation for di-(2-ethylhexyl) phthalate (DEHP)-plasticized poly(vinyl chloride) was studied by measuring time-resolved small-angle X-ray scattering (SAXS) and a flow of the solutions in test tube. It was found that for the gelation there were three regimes. At Regime I, the solution rapidly changed to a gel, and the SAXS intensity showed a peak and the peak intensity increased, keeping the peak angle constant. Applying the SAXS intensity to the kinetic analysis of the liquid-liquid phase separation, it was revealed that the spinodal decomposition proceeded to develop a periodic length of 29.9 nanometer in size, a hydrogen-bonding-type association in polymer rich phase followed, and then it induced fast gelation rate. At Regime II, the gelation slowly occurred and the SAXS intensity was not observed, suggesting that a homogeneous gel network was formed by a hydrogen-bonding. At regime III, the solution was a homogeneous sol.

• 한국터널지하공간학회 논문집
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• 제22권4호
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• pp.367-381
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• 2020

본 연구는 강관다단 그라우팅 공법의 Seal재의 배합비 결과에 대한 연구이다. 현재 국내에는 Seal재의 적정 겔화시간 및 초결시간에 대한 명확한 기준이 없는 실정이며, 이를 확인할 수 없어 품질관리에도 어려움이 있다. 이에 Seal재의 배합비를 4가지로 구성하여 실내 실험을 진행하였으며, 이를 통해 겔화시간 및 블리딩양을 확인하였다. 또한 비카트침 관입 실험을 통해 초결시간을 확인하고 각 배합비의 비교를 진행하였다. 그리고 W/C 120%에 대한 추가적인 실험을 통해 교반 속도와 시간이 Seal재에 미치는 영향을 파악하였다. 실내실험을 기반으로 총 3가지의 배합비에 대한 현장 실험을 진행하였으며, 시료의 초결시간 확인 및 본주입을 통한 구근 형성 크기와 강도를 비교하였다. 비교 결과 W/C가 낮을수록 강도가 강하고 구근의 크기가 크며, 초결 시간이 빠르게 나타나는 결과를 확인하였다. 겔화시간과 초결시간 결과를 통해 실제 현장에 적용 시 W/C 120%의 배합비가 가장 적절할것으로 나타났다.

• 한국식품과학회지
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• 제27권4호
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• pp.483-486
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• 1995

가공적성이 우수한 알코올처리 각시가자미껍질 젤라틴을 식품산업소재로 이용하기 위한 기초자료를 얻을 목적으로 젤라틴농도, pH, 정치온도 및 시간과 같은 겔화조건에 대한 알코올처리 젤라틴의 물리적 특성 및 색조의 변화를 알코올 무처리 젤라틴과 비교하여 검토하였다. 알코올처리 및 무처리 젤라틴이 모두 농도가 증가할수록 겔강도, 졸화온도 및 겔화온도 및 점도 등과 같은 물리적 특성은 증가하였다. 젤라틴 졸의 pH가 에탄올처리한 젤라틴의 경우 6.0일 때, 무처리한 젤라틴의 경우 5.0일 때 겔강도, 졸화온도 및 겔화온도가 가장 높았으나, $pH\;5.0{\sim}8.0$의 범위에서는 거의 차이가 없었고, pH 5.0 이하 및 pH 9.0 이상에서는 급격히 감소하였다. 젤라틴 졸을 겔화시키기 위하여 정치시키는 경우 온도는 낮을수록, 시간은 길수록 겔강도 및 졸화온도는 높았다. 겔화조건을 동일하게 하였을 때 에탄올처리한 젤라틴이 무처리한 젤라틴보다 물리적 특성이 우수하였다.

• 한국식품과학회지
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• 제25권4호
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• pp.404-406
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• 1993

시판되고 있는 초고온 멸균유의 저장 중 겔 형성을 추적하기 위하여 제품을 실온에 저장하면서 2,4,6-trinit-robenzene sulfonic acid를 이용하여 유리 아미노그룹을 정량하고 pH와 알콜 안정성을 측정하였다. 유리아미노그룹은 저장초기에 $0.94{\sim}1.11{\mu}M$이었고 $5{\sim}6$개월째에는 $1.95{\sim}2.17{\mu}M$이었으며 12개월째에는 $4.95{\sim}6.36{\mu}M$ 로 증가하였다. 시료의 pH는 저장초기에는 6.72이었고 $5{\sim}6$개월째에는 $6.49{\sim}6.55$이었으며 12개월째에는 $6.14{\sim}6.16$으로 서서히 감소하였다. 알콜시험에서 시료는 저장 $5{\sim}6$개월째부터 양성반응을 보여 카제인의 불안정성과 겔 형성의 개시를 추정케 하였다. 이상의 결과로 시판되는 초고온 멸균유의 겔 형성은 제조 후 정기적으로 몇 가지 요소들을 측정함으로써 추적될 수 있고 이 방법들은 제품의 품질관리에 도움이 될 것으로 생각된다.

• The Journal of the Acoustical Society of Korea
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• 제21권3E호
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• pp.126-131
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• 2002

Ultrasonic measurements are made in egg white to study the properties of the solution of the natural protein. The high-Q ultrasonic resonator method is used to get the ultrasonic absorption spectra over the range 0.2-10 ㎒ at 20℃. It is proportional to the 1.25th power of the frequency. The gelation process caused by heat is studied from the change in the velocity and the absorption. at 3 ㎒ using the pulse echo overlap technique over the range of 10-80℃. The absorption decreases with increasing temperature up to 60℃ where it turns up sharply and rapidly increases thereafter. The strong absorption in the gel region is described by the interaction between the solution and the network structure made of protein. Very slow variation in time elapse is observed after the temperature is quickly raised. It would be a real-time observation of the network building process and the characteristic time for the process is shown to be 400 min. A hysteresis phenomenon with respect to the temperature is observed. This phenomenon is associated with the memorizing effect of the network structure of protein of the gel.

• 대한전기학회논문지:전기물성ㆍ응용부문C
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• 제54권12호
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• pp.573-577
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• 2005

[$TiO_2$] sol and $SiO_2$ sol were prepared using sol-gel method. As $H_{2}O$/Alkoxide ratios increased, sol had cluster structure and as $H_{2}O$/Alkoxide ratios decreased, sol had linear structure. Gelation time of $TiO_2$ sol was faster than that of $SiO_2$ sol according to the time. In comparison with initial viscosity between $TiO_2$ sol and $SiO_2$ sol, $TiO_2$ sol was highest at $H_{2}O/Ti(OC_{3}H_{7})_{4}=5$, $SiO_2$ sol was almost constant according to $H_{2}O/Si(OC_{2}H_{5})_{4}$ ratios.

• 한국복합재료학회:학술대회논문집
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• 한국복합재료학회 2001년도 춘계학술발표대회 논문집
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• pp.110-113
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• 2001

Dielectrometry has been used to monitor the cure of epoxy resin using composite matrix. In this investigation, physical properties of the mixture of epoxy resin(LY564), bisphenol A type, and cycloaliphatic hardener(HY 2954) were observed. Activation energy at maximum tan $\delta$ and gelation point was determined during isothermal scanning. From IonViscosity data, it was found that vitrification peak after gelation was appeared on slow heating rate. It was also measured that the duration time for full cure was necessary and it was about 24 hr at $145^{\circ}C$. Therefore, epoxy resin used in this research is required the extended time for full cure.

• 대한전기학회논문지:전기물성ㆍ응용부문C
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• 제53권11호
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• pp.561-565
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• 2004

SiO₂ thin films are fabricated using sol-gel method and dipping method. Gelation time is faster according to increasing the amount of H₂O except H₂O/Si(OC₂H/sub 5/)₄=4. Initial viscosity is highest at H₂O/Si(OC₂H/sub 5/)₄=6. Gelation time is faster according to increasing the amount of CH₃COOH. The relative dielectric constant of thin films decreases a little according to increasing the measuring frequency. The dielectric dissipation factor of thin films increases a little below 100kHz and it increases rapidly over 100kHz.