• Journal of the Korean Society of Food Science and Nutrition
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• v.32 no.8
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• pp.1239-1244
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• 2003

Microcapsules were prepared by coacervation method using acetone/liquid paraffin system to control the ripening of kimchi. Eudragit E100, which was soluble at below pH 5.0 in aqueous solution, was used to make microcapsules to be sensitive to acidity of kimchi. The microcapsules with Eudragit E100 containing grapefruit seed extract (GFSE) showed the highest yield of 92.13%, the size of microcapsules was decreasing as increasing the amount of aluminium stearate, a dispersing agent. Morphology of the microcapsules determined by scanning electron microscopy showed spherical forms. GFSE, encapsulated antimicrobial agents, was quickly released at acidic buffer (pH 4,5,6) within 1 storage day. However, 70% of encapsulated GFSE in Eudragit E100 microcapsules was continuously released at pH 7 till 3 days, and it was sustained till 9 days. Characteristics of kimchi containing microcapsules of GFSE were analysed with ripening period. Decease of pH in kimchi was retarded with the added GFSE microcapsules till 2 days of fermentation, but GFSE did not affect pH in kimchi after 3 days. Total numbers of microorganisms and lactic acid microorganisms in kimchi were decreased with increasing the amount of the added GFSE microcapsules, however, the effect of controlled released GFSE from pH sensitive Eudragit E100 microcapsules was hard to detect. These results suggest the possibility of pH sensitive microcapsules for high qualify of kimchi.

• The Korean Journal of Zoology
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• v.31 no.3
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• pp.165-176
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• 1988

Stmcturai changes at the surfaces of oocytes of Pseudopotamilla occelata were examined by electron microscopy. The oocytes, which grow up to the flnai stage in the same coelomic fluid, once released from the ovary at 5 $\mu$ m stage, change in the structure of the vitelilne envelopes. Microvilli were found to change gready in structure, abundance and behaviour dudng oogenesis. Microvilli are short and bifurcated at the previtellogenic stages and grow in size, but the number increases only during previtellogenesis but decreases during vitellogenesis. Glycocaiyx structures begin to form at the tips of microvitli at the early previtellogenic stages and become more abundant as oocytes grow and remain at the final stage of oogenesis. The tips of microvilli are separated from the stems at the late vitellogenic stages to form vesicles simultaneously with retraction of the microvilli. Vitelline envelope consists of outer, intermediate and inner layers at the previtellogenic stages. However, the inner layer becomes thickened and differendated into two sublayers at 80 $\mu$m stage, - while the outer and intermediate layers remain constant in the thickness. These structural changes were presumably the results of functional differentiation of the vitelline envelope throughout oogenesis even in the same milleu.

• Journal of the korean academy of Pediatric Dentistry
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• v.28 no.4
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• pp.683-693
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• 2001

The purpose of this study was to evaluate the effects of Er:YAG laser on cutting efficacy and its histologic findings. Dentin specimens of human premolars and molars were used and irradiated by Er:YAG laser with noncontact handpiece type delivery system under different treatment condition of irradiation time. Cavity pattern and volume were evaluated to determine the cutting efficacy and following results were obtained. 1. Cutting volume of sound dentin was getting larger with time immersed in water increase 2. With the condition of irradiation (150mJ, 10Hz, 30sec), surface irregularity was more increased in sound dentin comparing to carious dentin. For the light microscopic examination, dentinal tubules were opened and ash flecks and cracks were noted with inconsistence of dentinal tubules. 3. In case of 30 sec. irradiation in carious dentin, dark zone was limited to small focus whereas 1 min. irradiation, more wider, and cracks were noted in the perpendicular to direction of dentinal tubules. For the 2 min. irradiation, cavity was the widest and more cracks were found.

• Journal of Radiation Protection and Research
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• v.36 no.3
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• pp.140-147
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• 2011

Our purpose is to specify behavior and environmental factors aimed at reducing the exposed dosage caused by PET-CT and to develop radiation safety management guidelines adequate for domestic circumstances. We have used a multistep-multimethod as the methodological approach to design and to carry out the research both in quality and quantity, including an analysis on previous studies, professional consultations and a survey. The survey includes responses from 139 practitioners in charged of 109 PET-CTs installed throughout Korea(reported by the Korean Society of Nuclear Medicine, 2010). The research use 156 questions using Cronbach's ${\alpha}$ (alpha) coefficients which were: 0.818 for "the necessity of setting and installing the radiation protective environment"; 0.916 for "the necessity of radiation protection", "setting and installing the radiation protective environment"; and 0.885 for "radiation protection". The check list, derived from the radiation safety management guidelines focused on behavior and environment, was composed of 20 items for the radiation protective environment: including 5 items for the patient; 4 items for the guardian; 3 items for the radiologist; and 8 items applied to everyone involved; for a total of 26 items for the radiation protective behavior including: 12 items for the patient; 1 item for the guardian, 7 items for the radiologist; and 6 items applied to everyone involved. The specific check list is shown in(Table 5-6). Since our country has no safety management guidelines of its own to reduce the exposed dosage caused by PET-CTs, we believe the guidelines developed through this study means great deal to the field as it is not only appropriate for domestic circumstances, but also contains specific check lists for each target who may be exposed to radiation in regards to behavior and environment.

• Polymer(Korea)
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• v.38 no.6
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• pp.760-766
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• 2014

Bead type super-absorbent resins to be used for release-control were prepared by modification of the inverse suspension polymerization, and their physical properties were characterized. Acrylic acid and acrylamide were used as monomers, and N,N-methylenebisacrylamide was used as crosslinker, controlling the viscosity of monomer solution by adding hydroxyethylcellulose (HEC). SEM studies of the synthesized beads verified that the bead surfaces had many pores with their diameters of several tens nm. The bead sizes were in the range of $500{\sim}3000{\mu}m$, depending on the viscosity of the monomer solution. Both absorbent amount and absorbent rate of the beads were inversely proportional to the bead size, and the maximum water absorbent amount of 1 g beads was determined to be ca. 170~200 g for 5 hrs. The absorbent rate was also dependent on pH change of the aqueous solution, exhibiting the maximum rate in pH ranging from 5 to 11. The absorbent rate decreased as the concentration of salt (NaCl and $MgCl_2$) or ethanol and ethylene glycol increased. Release time of the water absorbed into the bead resins was 700 hrs, confirming the usefulness of the resin for the good release-control materials.

• Journal of Adhesion and Interface
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• v.13 no.1
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• pp.17-23
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• 2012

A fragrant microcapsule was prepared for use by students to reduce the stress of taking examinations. Rosmarinic acid was used as a fragrant oil which had the effect of relaxing stress, polycaprolactone (PCL) was used as a capsule wall material, and poly(vinyl alcohol) (PVA) as a stabilizer. The solvent evaporation method was used to form the microcapsule. The microcapsules were prepared by changing the stirring rate, the concentration of the stabilizer, and the molecular weight of PCL. The shape of the microcapsule was characterized by scanning electron microscopy (SEM). The size of the microcapsule was reduced by increasing the stirring speed. The release rate of rosmarinic acid was decreased when the higher molecular weight PCL was used. When the prepared microcapsule was tested in an aromatherapy class, the microencapsulated fragrant oil had a longer release time than the original fragrant oil. The study data showed that this fragrant oil was effective for increasing concentration ability, reducing stress, increasing digestive power, and increasing memory for the students.

• Journal of radiological science and technology
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• v.29 no.1
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• pp.13-19
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• 2006

The PET scanner can detect the photon pair arriving from the source in phantom. The number of light photons released by the crystal(scintillator-BGO or LSO). In recent scintillation crystals in block structures were incorporated into full ring systems, and their resulted marked improvement in spatial resolution and increase in a sensitivity to annihilations. The uniformity of the crystal sensitivity is very important to makes correct information of abnormal states in organs. These factors influenced by the dection efficiency of the scintillators. We have study about the uniformity of crystals to the annihilation, And study about the standard deviation to average counts. The relative standard deviation in central detector groups more uniformed than circumferenced detector groups. It is caused detected quanta of gamma ray by the geometrical factors of PET detector. PET cameras are available with different geometric arrangement and several parallel rings oriented in the axial direction. The center groups from 7th to 40th groups are comparatively uniform and sensitive. But at the circumferenced detectors decreased the sensitivity and uniformity.

• Polymer(Korea)
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• v.33 no.1
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• pp.7-12
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• 2009

PLGA microspheres have been known as an injectable system for tissue engineering. The purpose of this study was to investigate the condition of emulsion formation and cell adhesion on the microsphere surface. BSA-loaded PLGA microsphere was fabricated by oil-in-water (O/W) and water-in-oil-in-water (W/O/W) solvent evaporation method. Sodium alginate was dissolved in water phase to control initial burst release and to improve lag time by PLGA bulk degradation. In addition, the morphology of cells attached on the micro spheres was studied using a scanning electron microscopy (SEM). Cellular proliferation behavior of human disc cells cultivated on PLGA micro spheres was analyzed using a MTT assay. MTT assay revealed that the cells can attach and proliferate on PLGA microspheres. According to these results, we concluded that BSA -loaded alginate/PLGA microspheres can be used as an injectable system for tissue engineering application.

• Journal of the Korean Society of Radiology
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• v.13 no.6
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• pp.841-846
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• 2019

Effect of misalignment on the performance was evaluated for the development of time-of-flight(TOF)-PET detector. A pair of TOF-PET detector consists of Lutetium-yttrium oxyorthosilicate(LYSO) scintillation crystal with a volume of 3 mm × 3 mm × 20 mm and Geiger-mode avalanche photodiodes(GAPD) photo-sensor with a active area of 3.07 mm × 3.07 mm. Analog output signals from TOF-PET detector were sent to the pre-amplifier and then fed into the gain adjust circuit for achievement of gain homogeneity for each detector. The amplified signals were recorded and digitized by data acquisition system based on oscilloscope. The effect of the detector misalignment between LYSO and GAPD was examined for four different alignment offsets of 0.0 mm, 0.5 mm, 1.0 mm and 1.5 mm for a pair of TOF-PET detector. The photopeak position decreased from ~400 mV to ~250 mV with increasing detector misalignment. the energy resolution and time resolution were degraded from 11.6% to 16.2%, and from 477 ps to 632 ps, respectively. This study demonstrated that PET detector performance was degraded considerably depending on the detector misalignment, which would be a critical issue for the development of TOF-PET detector.

• Journal of KIISE:Software and Applications
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• v.32 no.7
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• pp.612-624
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• 2005

In this paper, we propose a surface-based registration using a gaussian weighted distance map for PET-CT brain image fusion. Our method is composed of three main steps: the extraction of feature points, the generation of gaussian weighted distance map, and the measure of similarities based on weight. First, we segment head using the inverse region growing and remove noise segmented with head using region growing-based labeling in PET and CT images, respectively. And then, we extract the feature points of the head using sharpening filter. Second, a gaussian weighted distance map is generated from the feature points in CT images. Thus it leads feature points to robustly converge on the optimal location in a large geometrical displacement. Third, weight-based cross-correlation searches for the optimal location using a gaussian weighted distance map of CT images corresponding to the feature points extracted from PET images. In our experiment, we generate software phantom dataset for evaluating accuracy and robustness of our method, and use clinical dataset for computation time and visual inspection. The accuracy test is performed by evaluating root-mean-square-error using arbitrary transformed software phantom dataset. The robustness test is evaluated whether weight-based cross-correlation achieves maximum at optimal location in software phantom dataset with a large geometrical displacement and noise. Experimental results showed that our method gives more accuracy and robust convergence than the conventional surface-based registration.