• Restorative Dentistry and Endodontics
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• v.9 no.1
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• pp.101-106
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• 1983

It was the purpose of this study to investigate the fracture mode of dental amalgam by observing the crack propagation, and to relate this to the microstructure of the amalgam. Caulk 20th Century Regular, Caulk Spherical, Dispersalloy, and Tytin amalgam alloys were used for this study. After each amalgam alloy and Hg measured exactly by the balance was triturated by the mechanical amalgamator (Capmaster, S.S. White), the triturated mass was inserted into the cylindrical metal mold which was 4 mm in diameter and 12 mm in height and was pressed by the Instron Universal Testing Machine at the speed of 1mm/min with 120Kg. The specimen removed from the mold was stored in the room temperature for a week. This specimen was polished with the emery papers from #100 to #200 and finally on the polishing cloth with 0.06${\mu}Al_2O_3$ powder suspended in water. The specimen was placed on the Instron testing machine in the method similar to the diametral tensile test and loaded at the crosshead speed of 0.05mm/min. The load was stopped short of fracture. The cracks on the polished surface of specimen was examined with scanning electron microscope (JSM-35) and analyzed by EPMA (Electron probe microanalyzer). The following results were obtained. 1. In low copper lathe-cut amalgam, the crack went through the voids and ${\gamma}_2$ phase, through the ${\gamma}_1$ phase around the ${\gamma}$ particles. 2. In low copper spherical amalgam, it was observed that the crack passed through the ${\gamma}_2$ and ${\gamma}_1$ phase, and through the boundary between the ${\gamma}_1$ and ${\gamma}$ phase. 3. In high copper dispersant (Dispersalloy) amalgam, the crack was found to propagate at the interface between the ${\gamma}_1$ matrix and reaction ring around the dispersant (Ag-Cu) particles, and to pass through the Ag-Sn particles. 4. In high copper single composition (Tytin) amalgam, the crack went through the ${\gamma}_1$ matrix between ${\eta}$ crystals, and through the unreacted alloy particle (core).

• KIEAE Journal
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• v.10 no.2
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• pp.39-48
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• 2010

PAJU Book City Plan was designed to integrate two concepts of "Publishing Productive City" and "Ecological City" with the goal of "bringing of human being and nature together". This research on the post occupancy evaluation on PAJU Book City has two aims; One is to define how people, mainly working there rather than living, recognize the city and the other is to identify the problems resulted from the first phase of planning process and to suggest feasible solutions at the same time. It would be desirable that the outcome of this research should be used as data sources to improve the second phase of the plan. The evaluation criteria were created by the pre-survey on the basis of previous researches and "Pa Ju publishing city architectural design guide book (1999)". With those criteria, on-site questionnaire was conducted among people who work in PAJU Book City and stratified sampling was used for the proper sampling. The result is as follows; the visual-aesthetic criteria had positive response, which also closely related to a city satisfaction. Considering this result, construction type, circumferential environment of the building and a place of building form were found appropriate. The evaluation on the physical-ecological criteria was relatively low. Respondents were unsatisfied with green space and required better ecological waterway and more roadside tree. As green space was given a lot of weight in satisfaction survey, more green urban areas should be planned in the next phase. The evaluation on the social-behavior criteria got the lowest score. Particularly, the accessibility and convenient facilities were remarkably low. Nonetheless, the self-conceit about PAJU Book City was highly evaluated and played a crucial role in a city satisfaction. In order to achieve the goal, physical beauty, characteristics as a publication city as well as an ecologically sustainable city should be main agenda in the second phase of Paju Book City Plan. Consequently, it is important to strike a balance between the external environment and image media in order that PAJU Book City should be re-born as a culture city.

• Journal of Advanced Marine Engineering and Technology
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• v.38 no.9
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• pp.1141-1145
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• 2014

When the stator windings of 3 phase induction motors are in wrong condition, the mutual inductive responses between windings can be utilized for the purpose of diagnosing motors in that fault windings affect even the responses by DC excitation. Three phase induction motors are supposed to generate consistent inductive voltages at the remaining windings when exciting DC current is given to one of 3 windings, while the inconsistence of their voltages indicates the existence of disorder at electric motors. This study describes how the exciting current to one of three windings cause the other windings to create induced voltages, analyzing responses by transfer functions, and discloses whether or not the balance relation at two windings is normal in the way of measuring the differential voltage of their outputs. For experiment, common analog multi-testers is used for applying exciting current and measuring the output signal to confirm whether the proposed method is useful enough to be able to discriminate wrong polarities of windings onboard vessels including also the case of exciting current by AC.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.9 no.4
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• pp.387-395
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• 1999

The strain, surface and interfacial energies of III-V ternary systems were calculated for three kinds of structure modes: the Frank-van der Merwe(FM) mode, the Stanski-Krastanov(SK) mode and the Volmer-Weber(VW) mode. The free energy for each mode was estimated as functions of thickness and composition or lattice misfit. Through comparison of the free energy of each mode, it was found that the thickness-composition phase diagrams of III-V ternary systems can be determined only by considering the balance of the free energy and three kinds of structure modes appear in the phase diagrams. The SK mode appears only when the lattice misfit is large and/or the lattice layer is thick. The most stable structure of the SK mode is a cluster with four lattice layers or minimum thickness on a wetting layer of increasing lattice layers. The VW mode appears when the lattice misfit is large and the lattice layer is thin and only in the INPSb/InP and GaPSb/GaP system which have the largest lattice misfit of III-V ternary systems. The stable region of the SK mode in the GaPSb/GaP and InPSb/InP phase diagrams is largest of all because the composition dependence of the strain energy of these systems is stronger than that of the other systems. The critical number of lattice layers below which two-dimensional(2D) layers precede the three-dimensional(3D) nucleation in the SK mode at x=1.0 depends on the lattice misfit.

• The Transactions of the Korean Institute of Power Electronics
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• v.8 no.6
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• pp.469-477
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• 2003

This paper proposes a Carrier-Rotation (CR) PWM technique that is a new solution for the voltage unbalancing problem of flying capacitors in the Flying Capacitor Multi-level Inverter (FCMI). The proposed technique equalizes the utilization of phase leg voltage redundancies corresponding to the charging and the discharging state of individual flying capacitors during each switching period of all the switches. Therefore, the charging and the discharging quantity of flying capacitors are equal, which makes the average variation of flying capacitor voltages become zero and keeps their voltage stable during minimum specified period. It also has the reduced harmonic contents of output voltage and the same switch utilization since all the carrier signals are in phase and the switching frequency of each switch is identical. The proposed technique is analyzed precisely in flying capacitor 3-level inverter and then it has expanded to the FCMI (N-level, N>3). Experimental results on the laboratory prototype flying capacitor 3-level inverter confirm the validity of the proposed technique.

• Proceedings of the Korea Society of Poultry Science Conference
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• 2003.11a
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• pp.73-74
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• 2003

Three experiment were designed to determine the effects of dietary(n-3) fatty acids on the growth-suppressive effects of the inflammatory response and anti-oxidant enzyme activity and balances of nitrogen and energy. Day-old chicks were fed diets containing 1.0 ％ soybean oil in experiment 1, or diets containing 1.0 ％ of fish oil in experiment 2, and then on 7-d of age chicks were fed diets containing 1.0 ％ of either soybean oil or fish oil. In experiment 3, day-old chicks were fed on diets containing 1.0 ％ of either soybean oil or fish oil. In chicks of half pens within each dietary treatments of each experiments, the acute phase response were induced by injecting with Salmonella typhymurium lipopolysaccaride(LPS) i.p. 3 times at 8, 10 and 12-d of age. During acute phase response, chicks fed dietary fish oil from 1-d of age enhanced energy balances and did not give negative effect on nitrogen balance and uric acid excretion, but elevated MnSOD and Cu/ZnSOD activity In liver and erythrocyte cytosols compared with those fed dietary soybean oil. The results indicated that enhanced daily gain and metabolizable energy value of diet in birds fed fish oil from one-d of age seems due to change on the antioxidants systems during acute phase response.

• The Korean Journal of Pain
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• v.36 no.1
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• pp.51-59
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• 2023

Background: This study investigated the effect of an excess and a deficit of spinal 5-hydroxytryptamine (5-HT) on the mechanical allodynia and neuroglia activation in a rodent pain model of carrageenan inflammation. Methods: Male Sprague-Dawley rats were implanted with an intrathecal (i.t.) catheter to administer the drug. To induce an excess or deficit of 5-HT in the spinal cord, animals were given either three i.t. 5-HT injections at 24-hour intervals or a single i.t. injection of 5,7-dihydroxytryptamine (5,7-DHT) before carrageenan inflammation. Mechanical allodynia was measured using the von Frey test for 0-4 hours (early phase) and 24-28 hours (late phase) after carrageenan injection. The changes in the activation of microglia and astrocyte were examined using immunofluorescence of the dorsal horn of the lumbar spinal cord. Results: Both an excess and a deficit of spinal 5-HT had no or a minimal effect on the intensity of mechanical allodynia during the early phase but prevented the attenuation of mechanical allodynia during the late phase, which was observed in animals not treated with i.t. 5-HT or 5,7-DHT. Animals with an excess or deficit of 5-HT showed stronger activation of microglia, but not astrocyte, during the early and late phases, than did normal animals. Conclusions: Imbalance in the descending 5-HT pathway in the spinal cord could aggravate the mechanical allodynia and enhance the activation of microglia, suggesting that the spinal 5-HT pathway plays an essential role in maintaining the nociceptive processing in balance between facilitation and inhibition in inflammatory pain caused by carrageenan inflammation.

• Restorative Dentistry and Endodontics
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• v.8 no.1
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• pp.89-96
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• 1982

The purpose of this study is to identify the phases of four different types, low-copper lathe cut (Type II, class 1) and spherical (Type II, class 2) amalgam alloys which are made by Caulk company and high copper Dispersalloy (Type II, class 3) made by Johnson & Johnson and Tytin (Type I, class 2) made by S.S. White and to determine the Vickers hardness number on the individual phase and four different types of dental amalgam. After each amalgam alloy and Hg measured exactly by the balance was triturated by the mechanical amalgamator (De Trey), the triturated mass was inserted into the cylindrical metal mold which was 4 mm in diameter and 12mm in height and was pressed by the Instron Universal Testing machine (Model 1125) at the speed of 1mm/minute with 143$kg/cm^2$ according to the A.D.A. Specification No. 1. The Specimen removed from the mold, mounted and stored in the room temperature for 7 days. The speciman was polished with the emery paper from #220 to #1200 and finally on the polishing cloth with 0.3 and 0.05 um $Al_2O_3$ powder suspended in water. And then each specimen was etched by Allan's method and washed with Sodium Bisulfinite for 30 seconds. Finally differentiation and metallography on each phase were obtained by using metallographical microscope (Versamet, Union) and microhardness was obtained by using microhardness tester (MVH-2, Torsee). The results were as follows: 1. In the low-copper amalgam, the ${\gamma}$, ${\gamma}_1$ and ${\gamma}_2$ phase were observed and in the high-copper amalgam, the ${\gamma}$, ${\gamma}_1$. ${\epsilon}$ and ${\eta}$ phases were observed but ${\gamma}_2$ phase was not observed. 2. Among the microhardness of each amalgam phase measured under pressing a vickers diamond indenter with 2.0gm load for 30 seconds, e phase has the highest V.H.N (314 ${\pm}$ 20), and in low-copper amalgam 12 phase has the lowest V.H.N. (29${\pm}$1) and ${\eta}$ phase which was observed in high-copper amalgam has 230${\pm}$13 V.H.N and this phase is considerd to contribute to strengthen the handness in amalgam. 3. The V.H.N. measured under pressing a Vickers diamond indenter with 300.0gm load for 30 seconds in low-copper amalgam was lower than that of high-copper amalgam.

• Bulletin of the Korean Chemical Society
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• v.31 no.5
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• pp.1192-1198
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• 2010

Pharmaceuticals and personal care products (PPCPs) are emerging contaminants in the aquatic environment. Many pharmaceuticals are not completely removed during wastewater treatment, leading to their presence in wastewater treatment effluents, rivers, lakes, and ground water. Here, we developed analytical methods for monitoring ten pharmaceuticals from surface water by LC/ESI-MS/MS. For sample clean-up and extraction, MCX (mixed cation exchange) and HLB (hydrophilic-lipophilic balance) solid-phase extraction (SPE) cartridges were used. The limits of detection (LOD) in distilled water and the blank surface water were in the range of 0.006 - 0.65 and 1.66 - 45.05 pg/mL, respectively. The limits of quantitation (LOQ) for the distilled water and the blank surface water were in the range of 0.02 - 2.17 and 5.52 - 150.15 pg/mL, respectively. The absolute recoveries for fortified water samples were between 62.1% and 125.4%. Intra-day precision and accuracy for the blank surface water were 2.9% - 24.1% (R.S.D.) and -16.3% - 16.3% (bias), respectively. In surface wastewater near rivers, chlortetracycline and acetylsalicylic acid were detected frequently in the range of 0.017 - 5.404 and 0.029 - 0.269 ng/mL, respectively. Surface water near rivers had higher levels than surface water of domestic treatment plants.

• Korean Journal of Applied Biomechanics
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• v.25 no.1
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• pp.123-130
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• 2015

Purpose : The purpose of this study was to investigate the reliability of 3D-inertia measurement unit (IMU) based shoes in gait analysis. This was done with respect to the results of the optical motion capturing system and to collect reference gait data of healthy subjects with this device. Methods : The Smart Balance$^{(R)}$ system of 3D-IMU based shoes and Osprey$^{(R)}$ motion capturing cameras were used to collect motion data simultaneously. Forty four healthy subjects consisting of individuals in 20s (N=20), 40s (N=13), and 60s (N=11) participated in this study voluntarily. They performed natural walking on a treadmill for one minute at 4 different target speeds (3, 4, 5, 6 km/h), respectively. Results : Cadence (ICC=.998), step length (ICC=.970), stance phase (ICC=.845), and double-support phase (ICC=.684) from 3D-IMU based shoes were in agreement with results of optical motion system. Gait data of healthy subjects according to different treadmill speeds and ages were matched to previous literature showing increased cadence and reduced step length for elderly subjects. Conclusion : Conclusively, 3D-IMU based shoes in gait analysis were a satisfactory alternative option in measuring linear gait parameters.