• Journal of the korean academy of Pediatric Dentistry
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• v.31 no.3
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• pp.516-526
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• 2004

Polymerization shrinkage of photoinitiation type composite resin cause several clinical problems. The purpose of this study was to evaluate the shrinkage strain stress, linear polymerization shrinkage, compressive strength and microhardness of recently developed composite resins. The composite resins were divided into four groups according to the contents of matrix and filler type. Group I : $Denfil^{TM}$(Vericom, Korea) with conventional matrix, Group II : $Charmfil^{(R)}$(Dentkist, Korea) with microfiller and nanofller mixture, Group III : $Filtek^{TM}$ Z250(3M-ESPE, USA) TEGDMA replaced by UDMA and Bis-EMA(6) in the matrix, and Group IV : $Filtek^{TM}$ Supreme(3M-ESPE, USA) using pure nanofiller. Preparation of acrylic molds were followed by filling and curing with light gun. Strain gauges were attached to each sample and the leads were connected to a strainmeter. With strainmeter shrinkage strain stress and linear polymerization shrinkage was measured for 10 minutes. The data detected at 1 minute and 10 minutes were analysed statistically with ONE-way ANOVA test. To evaluate the mechanical properties of tested materials, compressive hardness test and microhardness test were also rendered. The results can be summarized as follows : 1. Filling materials in acrylic molds showed initial temporary expansion in the early phase of polymerization. This was followed by contraction with the rapid increase in strain stress during the first 1 minute and gradually decreased during post-gel shrinkage phase. After 1 minute, there's no statistical differences of strain stress between groups. The highest strain stress was found in group IV and followed by group III, I, II at 10 minutes-measurement(p>.05). In regression analysis of strain stress, group III showed minimal inclination and followed by group II, I, IV during 1 minute. 2. In linear polymerization shrinkage test, the composite resins in every group showed initial increase of shrinkage velocity during the first 1 minute, followed by gradually decrease of shrinkage velocity. After 1 minute, group IV and group III showed statistical difference(p<.05). After 10 minutes, there were statistical differences between group IV and group I, III(p<.05) and between group II and group III(p<.05). In regression analysis of linear polymerization shrinkage, group II showed minimal inclination and followed by group IV, III, I during 1 minute. 3. In compressive strength test, group III showed the highest strength and followed by group II, IV, I. There were statistical differences between group III and group IV, I(p<.05). 4. In microhardness test, upper surfaces showed higher value than lower surfaces in every group(p<.05).

• Journal of the Korean Chemical Society
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• v.29 no.2
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• pp.73-79
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• 1985

The crystal and molecular structure of acetone 4-benzylthiosemicarbazone, $C_{11}H_{15}N_3S$, has been determined by the single crystal X-ray diffraction methods. The crystals are monoclinic, space group $P2_1/c$ with unit cell dimensions, a = 10.249(7), b = 11.403(9), c = 10.149(7)TEX>${\AA}$, ${\beta}$ = 90.9$(1)^0$ and z = 4. The intensities were collected on an automatic four-circle diffractometer with graphite-monochromated Mo-$K_{\alpha}$ radiation. The structure was solved by direct methods and refined by full matrix least-squares methods. The final R was 0.045 for 1554 observed reflections. S-C(8)-N(2)-N(3)-C(9)-C(10) atoms make a zigzag planar chain. There are no unusual bond lengths and angles. There are two independent hydrogen bonds in the crystal structure. One is N-H${\cdots}$S intermolecular hydrogen bond with the length of 3.555${\AA}$ and makes dimer-like units. The other is N-H${\cdots}$N intramolecular hydrogen bond with the length of 2.568${\AA}$. The structure was compared with those of other thiosemicarbazone derivatives.

• Korean Journal of Applied Biomechanics
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• v.25 no.2
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• pp.157-165
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• 2015

Object : The goals of this research were to make Performance Enhanced Model(PE) taken the largest performance index (PI) through artificial variation of principle components calculated by principle component analysis for trial data, and to verify the effect through comparing kinematic factors between trial data (Raw) and PE. Method : Ten subjects (5 men, 5 women) were recruited and 80% of their maximal record was considered. The PI is a regression equation. In order to develop PE, we extracted Principle components from trial position data (by Principle Components Analysis (PCA)). Before PCA, we made 17 position data to 3 row matrix according to components. We calculated 3 eigen value (principle components) through PCA. And except Y (medial-lateral direction) component (because motion of Y component is small), principle components of X (anterior-posterior direction) and Z (vertical direction) components were changed as following. Changed principle components = principle components + principle components ${\times}$ k. After changing the each principle component, we reconstructed position data using the changed principle components and calculated performance index (PI). A Paired t-test was used to compare Raw data and Performance Enhanced Model data. The level of statistical significance was set at $p{\leq}0.05$. Result : The PI was significantly increased about 12.9kg at PE ($101.92{\pm}6.25$) when compared to the Raw data ($91.29{\pm}7.10$). It means that performance can be increased by optimizing 3D positions. The difference of kinematic factors as follows : the movement distance of the bar from start to lock out was significantly larger (about 1cm) for PE, the width of anterior-posterior bar position in full phase was significantly wider (about 1.3cm) for PE and the horizontal displacement toward the weightlifter after beginning of descent from maximal height was significantly greater (about 0.4cm) for PE. Additionally, the minimum knee angle in the 2-pull phase was significantly smaller (approximately 2.7cm) for the PE compared to that of the Raw. PE was decided at proximal position from the Raw (origin point (0,0)) of PC variation). Conclusion : PI was decided at proximal position from the Raw (origin point (0,0)) of PC variation). This means that Performance Enhanced Model was decided by similar motion to the Raw without a great change. Therefore, weightlifters could be accept Performance Enhanced Model easily, comfortably and without large stress. The Performance Enhance Model can provide training direction for athletes to improve their weightlifting records.

• Applied Microscopy
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• v.24 no.3
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• pp.23-33
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• 1994

It is well known that dichlorvos (DDVP), an organophosphate insecticide in common use, is so easily and rapidly hydrolyzed and excreted that it has usually little toxic effect on human body. In these days, however, it is widely used as an industrial and domestic insecticide and as an anthelmintic agent for animals, so that the accident of chemical poisoning occurs frequently. DDVP acts as a powerful inhibitor of carboxylic esterase, which can cause accumulation of acetylcholine at the synapses so paralysis of muscle and the transmission failure in cholinergic synapses dueing to desensitization of acetylcholin receptor may occure. Moreover accumulation of the acetylcholine brings about the elevation of the cyclic-AMP, which alters the cellular metabolisms of nucleic acid, carbohydrate, protein and lipid. Present study has undertaken to investigate the cardiotoxic effect of DDVP by electron microscopic study. A total of 30 Sprague-Dawley strain rats, weighing about 250gm were used as experimental animals. 2mg/kg/day of DDVP is intraperitonealy injected 3 times with intervals of every other day. On 1 day, 3 days, 5 days, 7 days and 14 days after drug administration, the animals were sacrified by cervical dislocation. Left ventricular cardiac muscles were resected and sliced into $1mm^3$. The specimens were embedded with Epon 812 and prepared by routine methods for electron microscopical observation. All preparations were stained with lead citrate and uranyl acetate and then observed with Hitachi-600 transmission electron microscope. The results were as follows: 1. In the cardiac muscle of DDVP treated rats, mitochondria with disorganized double membrane and mitochondrial crista, and vacuole formation in mitochondrial matrix were observed. But structures of mitochondria were recovered to normal in 14 days group. 2. In the cardiac muscle of DDVP treated rats, cisternae of sarcoplasmic reticulum were dilated and sacculated. But these changes were recovered to normal in 14 days group. 3. In the cardiac muscle of DDVP treated rats, glycogen particles around damaged myofibrils were decreased. But amount of glycogen particles were restored in 14 days group. 4. In the cardiac muscle of DDVP treated rats, disruption and discontinuation of myofilaments and disorganization of Z-disc were observed. But the structures of myofibrils were recovered to normal in 14 days group. It is consequently suggested that DDVP would induce the reversible degenerative changes on the ultrastructures in cardiac muscle of rat.

• Fisheries and Aquatic Sciences
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• v.22 no.12
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• pp.31.1-31.12
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• 2019

Background: The black-chinned tilapia, Sarotherodon melanotheron, is the most abundant fish species in the Nakwa (an open lagoon) and Brenu (a closed lagoon) in the Central Region of Ghana. Aspects of the life history characteristics and the ecology of the fish populations in both lagoons were studied to assess the bio-ecological status of this important resource. Methods: Fish samples were obtained from fishermen that fish on the Nakwa and Brenu lagoons using cast, drag and gill nets. The age of the fish was assessed from otoliths analysis and its growth modelled following the von Bertalanffy growth function. Morphometric characteristics of the fish populations were analysed using power regression and ANOVA for parameters comparisons, and Student's t test to determine whether species grew isometrically. The percentage occurrence method was used to analyse the stomach contents of the fish. Results: A total of 382 fish samples from both lagoons were measured, comprising 209 from Nakwa lagoon and 176 from Brenu lagoon. The size and weight of fish samples ranged between 3.9-11.5 cm total length and 1.0-27.3 g for Nakwa Lagoon and 5.6-12.8 cm total length and 3.2-29.8 g for the Brenu Lagoon. The estimated von Bertalanffy growth parameters were L∞ = 12.04 cm and K = 2.76/year for the Nakwa Lagoon samples and L∞ = 13.44 cm and K = 3.27/year for Brenu Lagoon samples. Daily otolith incremental rate ranged from 0.01-0.03 mm per day to 0.01-0.02 mm per day for Nakwa and Brenu lagoons, respectively. Stomach content analysis of the fish samples revealed that the species are planktivorous and the range of food varied between the lagoons. Green algae were the most prevalent food item in the stomachs of the fish samples from Nakwa with the frequency of 69% whilst diatoms (80.5%) were most prevalent phytoplanktonic food item for the fish in Brenu lagoon. Conclusions: The estimates of asymptotic length for the species in both lagoons are close to known values of the species length at first sexual maturity and points to intensive fishing pressure. As a consequence, a comprehensive sample-based survey is required in both lagoons to derive estimates of management reference points. The results of the stomach content analysis are beneficial to the construction of diet matrix for ecosystem models of the two systems.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.18 no.1
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• pp.110-122
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• 1993

When voice is transmitted through packet switching network, there needs a overload control, that is, a control for the congestion which lasts short periods and occurrs in local extents. In this thesis, we analyzed the performance of the statistical packet voice multiplexer using the overload control strategy by bit dropping. We assume that the voice is coded accordng to (4,2) embedded ADPCM and that the voice packet is generated and transmitted according to the procedures in the CCITT recomendation G. 764. For the performance analysis, we must model the superposed packet arrival process to the multiplexer as exactly as possible. It is well known that interarrival times of the packets are highly correlated and for this reason MMPP is more suited for the modelling in the viewpoint of accuracy. Hence the packet arrival process in modeled as MMPP and the matrix geometric method is used for the performance analysis. Performance analysis is similar to the MMPP IG II queueing system. But the overload control makes the service time distribution G dependent on system status or queue length in the multiplexer. Through the performance analysis we derived the probability generating function for the queue length and using this we derived the mean and standard deviation of the queue length and waiting time. The numerical results are verified through the simulation and the results show that the values embedded in the departure times and that in the arbitrary times are almost the same. Results also show bit dropping reduces the mean and the variation of the queue length and those of the waiting time.

• Development and Reproduction
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• v.7 no.2
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• pp.113-118
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• 2003

Follicular fluid(FF) of mammalian Graafian follicles contains various kinds of proteins and proteinases that are believed to play important roles during follicular growth oocyte maturation and ovulation of mature oocytes. Previous studies of human FF(hFF) demonstrated the presence of many serine/threonine proteinases and matrix metalloproteinases such as gelatinases, however, little is known about the caseinases. Present study was aimed to examine the presence and the property of caseinolytic enzyme in hFF. Using casein zymographic method, it was found that hFF, human adult serum and cord serum exhibited one intense 80 kDa and another weak 78 kDa bands having caseinolytic activity. When inhibitors were added to the zymographic substrate buffer, caseinolytic activity of both 80 kDa and 78 kDa proteins were inhibited by othylenediarnine tetraacetic acid(EDTA) or soybean trypsin inhibitor(SBTI), but not by E-64, phenylmethylsulfonyl fluoride(PMSF) or 1,10-phenanthroline. Thus both enzymes appear to belong to a family of trypsin-like enzyme. Addition of EDTA to the zymographic substrate buffer almost abolished the caseinolytic activity of both enzymes. However, further addition of a divalent metal ion such as CaC $l_2$, MgC $l_2$, MnC $l_2$ or ZnC $l_2$ to the same buffer fully restored the enzyme activity at 5 mM concentration despite the presence of EDTA. Based upon these observations, 80 kDa and 78 kDa caseinolytic enzymes are present in human follicular fluid and they appear to be trypsin-like enzymes of which caseinolytic activity needs the presence of $Ca^{++}$, aM $g^{++}$, M $n^{++}$ or Z $n^{++}$././././.

• Applied Microscopy
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• v.27 no.3
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• pp.333-346
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• 1997

The ischemia and reperfusion injury of the skeletal muscles is caused by generation of reactive oxygen during ischemia and reperfusion. It is well known that over 4 hours of ischemia injures the skeletal muscles irreversibly. The author has demonstrated the effects of SOD (superoxide dismutase), DMTU (dimethyl thiourea) and ischemic preconditioning on ultrastructural changes of the muscle fibers in the rectus femoris muscles after 4 hours of ischemia and 1 day and 3 days of reperfusion. A total of 72 healthy Sprague-Dawley rats weighing from 200 gm to 250 gm were used as experimental animals. Under urethane(1.15 g/kg, IP, 2 times) anesthesia, lower abdominal incision was done and the left common iliac artery was occluded by using vascular clamp for 4 hours. The left rectus femoris muscles were obtained at 1 and 3 days after the removal of vascular clamp. The SOD (15,000 unit/kg) or DMTU (500 mg/kg) were administered intraperitoneally at 1 hour before induction of ischemia. The ischemic preconditioned group underwent three episodes of 5 minutes occlusion and 5 minutes reperfusion followed by 4 hours of ischemia and 1 day and 3 days of reperfusion. The specimens were sliced into $1mm^3$ and prepared by routine methods for electron microscopic observation. All specimens were stained with uranyl acetate and lead citrate and then observed with Hitachi-600 transmission electron microscope. The results were as follows: 1. SOD or DMTU alone did not affect the ultrastructure of muscle fibers in the rectus femoris muscles. The electron density of mitochondrial matrix was decreased by ischemic preconditioning. 2. Dilated cisternae of sarcoplasmic reticulum, triad, mitochondria and the loss of myofilament in the sarcomere were observed in the 4 hours ischemia and 1 day reperfused rectus femoris muscles. Markedly changed sarcoplasmic reticulum, triad, disordered or loss of myofilament, indistinct A-band and I-band, and irregular electron lucent M -line and Z-line are seen in the 4 hours ischemia and 3 days reperfused rectus femoris muscles. 3. SOD reduced the changes of organelles in the muscle fibers of the 4 hours ischemia and 1 day reperfused rectus femoris muscles of the rats, but SOD did not affect the changes of muscle fibers in the 4 hours ischemia and 3 days reperfused muscles. On the other hand, DMTU markedly attenuated considerably the ultrastructural change of the 4 hours ischemia and 1 day or 3 days reperfused rectus femoris muscles. 4. By the ischemic preconditioning, the change was attenuated remarkably in the 4 hours ischemia and 1 day reperfused rectus femoris muscles. As the ischemic reperfused changes of muscle fibers were regenerated or recovered by ischemic preconditioning, the ultrastructures of them were similar to those of normal control in the 4 hours ischemia and 3 days reperfused rectus formoris muscles. Consequently, it is suggested that DMTU is stronger inhibitor to ischemic reperfused change than SOD. The ischemia and reperfusion-induced muscular damage is remarkably inhibited by ischemic preconditioning.

• Food Science of Animal Resources
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• v.26 no.3
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• pp.402-409
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• 2006

Although microorganisms are, in fact, the most diverse and abundant type of organism on Earth, the ecological functions of microbial populations remains poorly understood. A variety of bacteria including marine Vibrios encounter numerous ecological challenges, such as UV light, predation, competition, and seasonal variations in seawater including pH, salinity, nutrient levels, temperature and so forth. In order to survive and proliferate under variable conditions, they have to develop elaborate means of communication to meet the challenges to which they are exposed. In bacteria, a range of biological functions have recently been found to be regulated by a population density-dependent cell-cell signaling mechanism known as quorum-sensing (QS). In other words, bacterial cells sense population density by monitoring the presence of self-produced extracellular autoinducers (AI). N-acylhomoserine lactone (AHL)-dependent quorum-sensing was first discovered in two luminescent marine bacteria, Vibrio fischeri and Vibrio harveyi. The LuxI/R system of V. fischeriis the paradigm of Gram-negative quorum-sensing systems. At high population density, the accumulated signalstrigger the expression of target genes and thereby initiate a new set of biological activities. Several QS systems have been identified so far. Among them, an AHL-dependent QS system has been found to control biofilm formation in several bacterial species, including Pseudomonas aeruginosa, Aeromonas hydrophila, Burkholderia cepacia, and Serratia liquefaciens. Bacterial biofilm is a structured community of bacterial cells enclosed in a self-produced polymeric matrix that adheres to an inert or living surface. Extracellular signal molecules have been implicated in biofilm formation. Agrobacterium tumefaciens strain NT1(traR, tra::lacZ749) and Chromobacterium violaceum strain CV026 are used as biosensors to detect AHL signals. Quorum sensing in lactic acid bacteria involves peptides that are directly sensed by membrane-located histidine kinases, after which the signal is transmitted to an intracellular regulator. In the nisin autoregulation process in Lactococcus lactis, the NisK protein acts as the sensor for nisin, and NisR protein as the response regulator activatingthe transcription of target genes. For control over growth and survival in bacterial communities, various strategies need to be developed by which receptors of the signal molecules are interfered with or the synthesis and release of the molecules is controlled. However, much is still unknown about the metabolic processes involved in such signal transduction and whether or not various foods and food ingredients may affect communication between spoilage or pathogenic bacteria. In five to ten years, we will be able to discover new signal molecules, some of which may have applications in food preservation to inhibit the growth of pathogens on foods.

• Proceedings of the KSMRM Conference
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• 2002.11a
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• pp.133-133
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• 2002

Purpose： The purpose of paper is to implement software to visualize brain fiber tract using a 24-bit color coding scheme and to test its feasibility. Materials and Methods： MR imaging was performed on GE 1.5 T Signa scanner. For diffusion tensor image, we used a single shot spin-echo EPI sequence with 7 non-colinear pulsed-field gradient directions： (x, y, z)：(1,1,0),(-1,1,0),(1,0,1),(-1,0,1),(0,1,1),(0,1,-1) and without diffusion gradient. B-factor was 500 sec/$\textrm{mm}^2$. Acquisition parameters are as follows： TUTE=10000ms/99ms, FOV=240mm, matrix=128${\times}$128, slice thickness/gap=6mm/0mm, total slice number=30. Subjects consisted of 10 normal young volunteers (age：21∼26 yrs, 5 men, 5 women). All DTI images were smoothed with Gaussian kernel with the FWHM of 2 pixels. Color coding schemes for visualization of directional information was as follows. HSV(Hue, Saturation, Value) color system is appropriate for assigning RGB(Red, Green, and Blue) value for every different directions because of its volumetric directional expression. Each of HSV are assigned due to (r,$\theta$,${\Phi}$) in spherical coordinate. HSV calculated by this way can be transformed into RGB color system by general HSV to RGB conversion formula. Symmetry schemes： It is natural to code the antipodal direction to be same color(antipodal symmetry). So even with no symmetry scheme, the antipodal symmetry must be included. With no symmetry scheme, we can assign every different colors for every different orientation.(H =${\Phi}$, S=2$\theta$/$\pi$, V=λw, where λw is anisotropy). But that may assign very discontinuous color even between adjacent yokels. On the other hand, Full symmetry or absolute value scheme includes symmetry for 180$^{\circ}$ rotation about xy-plane of color coordinate (rotational symmetry) and for both hemisphere (mirror symmetry). In absolute value scheme, each of RGB value can be expressed as follows. R=λw｜Vx｜, G=λw｜Vy｜, B=λw｜Vz｜, where (Vx, Vy, Vz) is eigenvector corresponding to the largest eigenvalue of diffusion tensor. With applying full symmetry or absolute value scheme, we can get more continuous color coding at the expense of coding same color for symmetric direction. For better visualization of fiber tract directions, Gamma and brightness correction had done. All of these implementations were done on the IDL 5.4 platform.