• Journal of the Society of Cosmetic Scientists of Korea
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• v.30 no.1
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• pp.53-58
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• 2004

In this study, we describe the application of electron microscopes that incorporate freeze treatments or cryo systems to achieve the characterization of the microstuctures of emulsions. We confirmed that the preparations of freezing replica method and with cryo systems were useful to clarify the microstuctures of the emulsions. This methodology will be able to contribute to understanding the relation between microstuctures and rheology of emulsions.

• Applied Microscopy
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• v.28 no.1
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• pp.83-90
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• 1998

The pathway of intracellular transport of dehydrocholic acid was investigated in the hepatocytes of rats by transmission electron microscopy with conventional and freeze fracture methods. Both in normal and experimental groups, the cis Golgi cisterns were sacculated and faces toward the bile canaliculus. In the experimental group, however, the cis Golgi cisterns showed buds, which were probably separated to be vesicles. Some of the buds were connected to the cisterns with the narrow neck. The vesicles were increased in the vicinity of bile canaliculi. The fusion between vesicles and bile canaliculus were frequently observed in the experimental group. This was particularly well shown in the freeze fracture replica. In the thin section, the vesicles were devoid of visible contents as seen in the bile canaliculli. The evidence suggests that the vesicles are derived from the cis Gogi cistern in the way that buds pinch off, serve as vehicles to transport dehydrocholic acids and fuse to bile canaliculi for exocytosis.

• Proceedings of the KIEE Conference
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• 1992.07b
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• pp.803-805
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• 1992

The InP single crystals were grown by Modified Synthesis Solute Diffusion (SSD) method and its properties were investigated. The crystal growth rate and lattice constant $a_{\circ}$ of the grown crystals were 1.8mm/day, 5.867${\AA}$ respectively. Etch pits density along growth direction of crystal had nearly uniformity' about (2-6)x10 $cm^{-2}$ from first freeze part to last freeze part. The carrier concentration, mobility and resistivity varied from 6.25 x $10^{15}cm^{-3}$, 4218 $cm^{2}$/V sec and 1.38 x $10^{-1}{\Omega}^{-cm}$ at the first freeze part to 8.8x$10^{-3}cm^{-3}$, 4012 $cm^{2}$/V.sec and 1.43 X $10^{-1}{\Omega}^{-cm}$ at the last freeze part. In the photoluminescence at 10K, the radiation transitions were observed by the near band edge recombination, D-A pair recombination and its phonon replica in the undoped InP.

• Applied Microscopy
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• v.25 no.2
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• pp.53-64
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• 1995

This study was designed to investigate the morphological alterations of zonula occludens, macula adherences and gap junctions between the hepatocytes in the fasting conditions. Animals (Sprague Dawley, $250{\sim}280g$) were divided into two groups: normal and fasting. The latter were fasted for eight days prior to sampling. Liver tissues were sectioned and replicated after freeze fracturing for the transmission electron microscopy. In the normal rat liver, the interhepatocellular space at the area of some zonula occludens appeared to be widened in thin sections. On the freeze fracture replicas., the zonula occludens appeared as an anastomosing network of $2{\sim}4$ strands or grooves on P or E faces. Free ends and fragments of the strands were observed. In the rat fasted for eight days, the hepatocytes were diminished in size and the organelles were decreased in number and size. The intercellular space was wide at many areas of zonula occludens in thin section. On the freeze fracture replicas, the zonula occludens showed diminution or disappearence of anastomosing network of strands or grooves. Free ends and small fragments of the strands or grooves were frequently encountered. The macula adherens was markedly increased in number in thin sections, although they could not be found on the freeze fracture replicas. The gap junctions were increased in number in thin sections. Small aggregations of the intramembranous particles appeared with larger ones on the freeze fracture replica. The evidences may suggest the followings: (1) The disassembly of zonula occludens in the fasting states is led from the diminished mechanical stress on the luminal surface of bile canaliculus with the impaired secretion of bile components from the hepatocytes. (2) The increase of macula adherens is necessary to maintain the liver parenchyma integrity in the fasting state which leads the hepatocyte to be diminished and finally the intercellular space to be separated. (3) The rise in both number and size of gap junctions is owing to the need of increasing intercellular communication between the hepatocytes during the fasting. (4) The alteration of zonula occludens is easily led by the physiological condition of hepatocytes even in the normal ones.

• Journal of Powder Materials
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• v.21 no.5
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• pp.366-370
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• 2014

The present study demonstrates the effect of solidification condition on the pore structure in freeze drying process using the slurries of CuO/sublimable vehicles. Camphene and Camphor-45 wt% naphthalene based slurries with 14 vol% CuO powder were frozen into a mold at $-25^{\circ}C$, followed by sublimation at room temperature. The green bodies were hydrogen-reduced and sintered at $500^{\circ}C$ for 1 h. The porous Cu specimen, frozen the CuO/camphene slurry into the heated mold of the upper part, showed large pores with unidirectional pore channels and small pores in their internal wall. Also, it was observed that the size of large pores was decreasing near the bottom part of specimen. The change of pore structure depending on the freezing condition was explained by the nucleation behavior of camphene crystals and rearrangement of solid powders during solidification. In case of porous Cu prepared from CuO/Camphor-naphthalene system, the pore structure exhibited plate shape as a replica of the original structure of crystallized vehicles with hypereutectic composition.

• 제어로봇시스템학회:학술대회논문집
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• 1997.10a
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• pp.179-182
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• 1997

In a training simulator for power plant, operator's action in the MCR(Main Control Room) are given to plant process and computer system model as an inputs, and the same response as in real power plant is provided in real time. Inter-process communication and synchronization are especially important among various inputs. In the plant simulator, to simulate the digital control system such as FOXBORO SPEC-200 Micro control system, modification and adaptation of control card(CCC) and its continuous display station(CDS) is necessary. This paper describes the modeling and simulation of FOXBORO SPEC-200 Micro control system applied to Younggwang nuclear power plant unit #3 & 4, and its integration process to the full-scope replica type training simulator. In a simulator, display station like CDS of FOXBORO SPEC-200 Micro control system is classified as ITI(Intelligent Type Instrument), which has a micro processor inside to process information and the corresponding alphanumeric display, and the stimulation of ITI limits the important functions in a training simulator such as backtrack, replay, freeze and IC reset. Therefore, to achieve the better performance of the simulator, modification of CDS and special firmware is developed to simulate the FOXBORO SPEC-200 Micro control system. Each control function inside control card is modeled and simulated in generic approach to accept the plant data and control parameter conveniently, and debugging algorithms are applied for massive coding developed in short period.

• Electrical & Electronic Materials
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• v.8 no.3
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• pp.291-297
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• 1995

The InP crystals have been grown by modified synthesis solute diffusion (SSD) method and its properties have been investigated. The crystals have been grown by lowering the crucible quartz for growth in the furnace and crystal growth rate is 1.8mm/day. The lattice constant a. of the grown crystals is 5.867.angs.. Etch pits density along growth direction of crystal changes from 3.0*10.sup 3/cm$\^$-2/ of first freeze part to 6.7*10$\^$4/cm$\^$-2/ of last freeze part and the radial direction of wafer shows nearly uniform distribution. The resistivity and the carrier concentration of the grown crystals are 1.43*10$\^$-1/.ohm.-cm, 7.7*10$\^$15/cm$\^$-3/ at room temperature, respectively. In the photolurninescence at 10K, the radiation transitions are observed by the near band edge recombination, a pair recombination due to Si donor - Zn acceptor and its phonon replica in the InP. The activation energy by Zn diffusion in undoped n-InP crystals is 1.22eV.

• Applied Microscopy
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• v.16 no.2
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• pp.1-13
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• 1986

The purpose of this study was to investigate the morphology and intercellular junctions of the odontoblast of dental pulp in the rat incisor by means of the freeze fracture electron microscopy. Twenty male Sprague-Dawley rats weighing $150{\sim}200g$ were used. After being anesthetized by an intraperitoneal injection of 0.5 ml sodium pentobarbital per kg in body weight(60 mg/ml) the animals were perfused with 2.5% glutaraldehyde-2% paraformaldehyde fixative in 0.1 M cacodylate buffer, pH 7.2 through the ascending aorta for one hour. The incisors were carefully extracted from the jaws and demineralized by suspending them in 0.1 M EDTA in 3% glutaraldehyde (pH 7.2) for two weeks. After demineralization, the specimens were obtained from the portion divided into five equal parts. For freeze-fracture replication, demineralized tissues were infiltrated for several hours with 10%, 25% glycerol in 0.1M cacodylate buffer as a cryoprotectant and then frozen in liquid Freon 22 and stored in liquid nitrogen. Fracturing and replication were done in Balzers BAF 400D high-vacuum freeze-fracture apparatus at $-120^{\circ}C$ under routine $5X10^{-7}$ Torr vacuum. The tissue was immediately replicated with platinum unidirectionally at $45^{\circ}$ angle and reinforced with carbon at $90^{\circ}$ angle unidirectionally or by using a rotary stage. The replication process was monitored by a quartz-crystal device. The replicas were immersed in 100% methanol overnight. The tissue was then digested from the replica by clorox (laundry bleach), placed into 5% EDTA, and washed repeatedly with distilled water. The replicas were picked up on 0.3% formvar-coated 75 mesh grids and examined in the JEOL 100B electron microscope. The results were as follows; 1. Both in thin sections and freeze-fracture replicas, three types of intercellular junctions were recognizable in the plasma membrane of odontoblast: gap junction, tight junction and desmosome-like junction. 2. The nuclear pores were evenly distributed over the nuclear envelope. The pore complex formed a ring about 70 nm in diameter. 3. Gap junctions were found between odontoblasts as well as odontoblasts and neighbouring pulp cells (fibroblast, subodontoblastic cell process, nerve-like fibre). Gap junctions, which were round, ellipsoid and pear-shaped and 600 nm in diameter, were observed in the odontoblast. 4. Numerous round and ellipsoid gap junctions could be frequently seen on the plasma membranes in cell body and apical part of the odontoblasts. On the P face, the junctions were recognized as a cluster of closely packed particles, measuring about 9 nm in diameter, and on the E face, the junctions were recognized as a shallow grooves.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.40 no.10
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• pp.865-871
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• 2016

In recent years, traditional scaffold fabrication techniques such as gas foaming, salt leaching, sponge replica, and freeze casting in tissue engineering have significantly limited sufficient mechanical property and cell interaction effect due to only random pores. Fused deposition modeling is the most apposite technology for fabricating the 3D scaffolds using the polymeric materials in tissue engineering application. In this study, 3D slurry mould was fabricated with a blended biphasic calcium phosphate (BCP)/Silica/Alginic acid sodium salt slurry in PCL mould and heated for two hours at $100^{\circ}C$ to harden the blended slurry. 3D dual-pore BCP/Silica scaffold, composed of macro pores interconnected with micro pores, was successfully fabricated by sintering at furnace of $1100^{\circ}C$. Surface morphology and 3D shape of dual-pore BCP/Silica scaffold from scanning electron microscopy were observed. Also, the mechanical properties of 3D BCP/Silica scaffold, according to blending ratio of alginic acid sodium salt, were evaluated through compression test.