• Journal of the Korean Society for Precision Engineering
• /
• v.28 no.7
• /
• pp.777-782
• /
• 2011

Micro features on the surface are well-known to have significant effects on optical or mechanical properties such as the optical interference, reflectance at the surface, contact angle, interfacial friction, etc. These surface micro features are increasingly employed to enhance the functionality of the applications in various application areas such as optical components for LCD or solar panel. Diverse surface features have been proposed and some of them are showing excellent efficiency or functionality, especially in optical applications. Most applications employing the micro features need manufacturing process for mass production and the injection molding and roll-to-roll forming, which are typical processes for mass production adopting polymeric materials, may be also preferred for micro patterned plastic product. Since the functionality or efficiency of the surface structures generally depends on the shape and the size of the structure itself or the array of the structures on the surface, it would be very important to replicate the features very precisely as being designed during the molding the micro pattern applications. In this paper, a series of research activities is introduced for roll-to-roll forming of micro patterned film including filling of patterns with UV curable resin, demolding of surface structures from the roll tool, control of surface energy and cure shrinkage of resin and dispose time and intensity of the UV light for curing of UV curable resin.

• Parasites, Hosts and Diseases
• /
• v.22 no.2
• /
• pp.153-160
• /
• 1984

An experimental study was undertaken to observe the difference in susceptibility of mouse strains to Metagonimus yokogawai infection by estimating it from worm recovery rate and dimension of worms. It was also studied the effects of prednisolone injection on the chronological pattern of worm recovery in ICR mice. The metacercariae were obtained from sweetfish and 300 in each number were given to 5 strains (CBH, A, DBA, $C^{57}BL$ and KK) of mice, and after 7 days period, the worms were collected from their intestine. Prednisolone at the dose of 10 mg/kg was injected to ICR mice every other day from 7 days prior to infection until sacrificed at 6 hours to 35th post-infection day. ICR mice infected with M. yokogawai but untreated were used for controls. The success rate in infection of mice ranged 25.0-83. 3% by strains, the worm recovery rate 1. 2-18. 9%, and the average size of worms O. 554-0. 683 mm long and 0.214-0.244 mm wide. The higher rates and larger size of worms were observed in KK and $C^{57}BL$ strains than others and the difference was statistically significant. In ICR mice for control, the worm recovery rate until 1 day after infection was relatively high (38-66%) but it became much lower (less than 0.7%) during 1-35 days. However, prednisolone injection brought about persistently high recovery rates (16-80%) until 21 days. It was concluded that the susceptibility to M. yokogawai infection is different by strains of mice but it can be elevated by prednisolone injection probably due to suppression of Immune respon3e3 in ICR mice.

• Korean Journal of Biological Psychiatry
• /
• v.16 no.1
• /
• pp.5-14
• /
• 2009

Objectives : Most of the mechanisms reported for antidepressant drugs are the enhancement of neurite outgrowth and neuronal survival in the rat hippocampus. Neural cell adhesion molecule 140(NCAM140) has been implicated as having a role in cell-cell adhesion, neurite outgrowth, and synaptic plasticity. In this report, we have performed to elucidate a correlation among chronic antidepressant treatments, NCAM140 expression, and activation of phosphorylated cyclicAMP responsive element binding protein(pCREB) which is a downstream molecule of NCAM140-mediated intracellular signaling pathway in the rat hippocampus. Methods : Fluoxetine(10mg/kg) was injected acutely(daily injection for 5days) or chronically(daily injection for 14days) in adult rats. RNA and protein were extracted from the rat hippocampus, respectively. Real-time RT-PCR was performed to analyze the expression pattern of NCAM140 gene and western blot analyses for the activation of the phosphorylation ratio of CREB. Results : Chronic fluoxetine treatments increased NCAM140 expression 1.3 times higher than control in rat hippocampus. pCREB immunoreactivity in the rat hippocampus with chronic fluoxetine treatment was increased 4.0 times higher than that of control. Conclusion : Chronic fluoxetine treatment increased NCAM140 expression and pCREB activity in the rat hippocampus. Our data suggest that NCAM140 and pCREB may play a role in the clinical efficacy of antidepressants promoting the neurite outgrowth and neuronal survival.

• Journal of the Korean Institute of Gas
• /
• v.26 no.3
• /
• pp.45-53
• /
• 2022

In order to improve the emission of diesel engines, natural gas-diesel dual fuel combustion compression ignition engines are in the spotlight. In particular, a reactivity controlled compression ignition (RCCI) combustion strategy is investigated comprehensively due to its possibility to improve both efficiency and emissions. With advanced diesel direct injection timing earlier than TDC, it achieves spontaneous reaction with overall lean mixture from a homogeneous mixture in the entire cylinder area, reducing nitrogen oxides (NOx) and particulate matter (PM) and improving braking heat efficiency at the same time. However, there is a disadvantage in that the amount of incomplete combustion increases in a low load region with a relatively small amount of fuel-air. To solve this, sensitive control according to the diesel injection timing and fuel ratio is required. In this study, experiments were conducted to improve efficiency and exhaust emissions of the natural gas-diesel dual fuel engine at low load, and evaluate combustion stability according to the diesel injection timing at the operation point for power generation. A 6 L-class commercial diesel engine was used for the experiment which was conducted under a 50% load range (~50 kW) at 1,800 rpm. Two injectors with different spray patterns were applied to the experiment, and the fraction of natural gas and diesel injection timing were selected as main parameters. Based on the experimental results, it was confirmed that the brake thermal efficiency increased by up to 1.3%p in the modified injector with the narrow-angle injection added. In addition, the spray pattern of the modified injector was suitable for premixed combustion, increasing operable range in consideration of combustion instability, torque reduction, and emissions level under Tier-V level (0.4 g/kWh for NOx).

• Tuberculosis and Respiratory Diseases
• /
• v.38 no.2
• /
• pp.143-154
• /
• 1991

Pneumconiosis is a sort of pulmonary fibrosis consequent to the inhalation of the respirable dusts. Thus, the pathogenesis of silicosis have concentrated largely on the early response of alveolar macrophage and the later fibroblastic stimulation. But the role of the other cells and continuing cell injury in the pathogenesis has not been fully studied. And the chemical factors such as prostaglandin, fibroblast stimulating factor and inhibiting factor and chemotaxin are also participated in the mechanism of pulmonary fibrosis in silicosis. In order to clarify the role of alveolar cells and prostaglandin, we investigated the changes of the cellularities in bronchoalveolar lavage fluid and tissue pathology in the experimental silicosis with the time sequence. The experimental animals were divided into 3 groups; control group received only intratracheal injection of 0.5 ml saline, silica group received the intratracheal instillation of 40 mg silica with the same amount saline, and aspirin group received 450 mg/kg of aspirin after silica instillation. The results were as follows: 1) The total cells of bronchoalveolar lavage fluid in the silica group markedly increased in comparison with the control group, but there was no significant difference between the silica and aspirin groups. 2) The percentages of alveolar macrophages to the total number of cells in the silica group tended to be lower than those in the control group and also lower than those in the aspirin group at the 1st week after silica instillation. 3) The percentages of neutrophils to the total number of cells in the silica group were significantly higher than those in the control group during the entire period and also higher than those in the aspirin group at the 3rd day after silica instillation. 4) In the silica group, the percentages of lymphocytes to the total number of cells were increased 143 progressively with the time course and those were significantly higher than those in the control group from the 3rd week after silica administration. There were marked differences of lymphocyte percentages between the silica and aspirin groups at the 1st week after silica instillation. 5) The inflammatory change was observed in the rat lung at the 1st day after silica instillation. Also the silicotic nodule appeared in the silica group at the 1st week but we could not find out that nodule in the aspirin group at that time. The fibrotic changes in the rat lung tended to be increased progressively with the time course, therefore, the diffuse fibrotic pattern appeared in the whole field at the 20th week after silica instillation. 6) By the electron microscopy, there were gradual increases of phagosomes and vacuoles in the alveolar macrophage in the silica group as compared with the control group. These results suggest that the neutrophils and the lymphocytes have also participated in the pulmonary fibrosis even though the alveolar macrophage has a major role, and prostaglandin mediate the inflammation and pulmanary fibrosis in the experimental silicosis.

• The Korean Journal of Physiology and Pharmacology
• /
• v.2 no.3
• /
• pp.297-305
• /
• 1998

This study used in vivo intracellular recording in rat hippocampus to evaluate the effect of lidocaine and MK-801 on the membrane properties and the synaptic responses of individual neurons to electrical stimulation of the commissural pathway. Cells in control group typically fired in a tonic discharge mode with an average firing frequency of $2.4{\pm}0.9$ Hz. Neuron in MK-801 treated group (0.2 mg/kg, i.p.) had an average input resistance of $3.28{\pm}5.7\;M{\Omega}$ and a membrane time constant of $7.4{\pm}1.8$ ms. These neurons exhibited $2.4{\pm}0.2$ ms spike durations, which were similar to the average spike duration recorded in the neurons of the control group. Slightly less than half of these neurons were firing spontaneously with an average discharge rate of $2.4{\pm}1.1$ Hz. The average peak amplitude of the AHP following the spikes in these groups was $7.4{\pm}0.6$ mV with respect to the resting membrane potential. Cells in MK-801 and lidocaine treated group (5 mg/kg, i.c.v.) had an average input resistance of $3.45{\pm}6.0\;M{\Omega}$ and an average time constant of $8.0{\pm}1.4$ ms. The cells were firing spontaneously at an average discharge rate of $0.6{\pm}0.4$ Hz. Upon depolarization of the membrane by 0.8 nA for 400 ms, all of the tested cells exhibited accommodation of spike discharge. The most common synaptic response contained an EPSP followed by early-IPSP and late-IPSP. Analysis of the voltage dependence revealed that the early-IPSP and late-IPSP were putative $Cl^--and\;K^+-dependent$, respectively. Systemic injection of the NMDA receptor blocker, MK-801, did not block synaptic responses to the stimulation of the commissural pathway. No significant modifications of EPSP, early-IPSP, or late-IPSP components were detected in the MK-801 and/or lidocaine treated group. These results suggest that MK-801 and lidocaine manifest their CNS effects through firing pattern of hippocampal pyramidal cells and neural network pattern by changing the synaptic efficacy and cellular membrane properties.

• Korean Journal of Animal Reproduction
• /
• v.23 no.3
• /
• pp.191-203
• /
• 1999

The objectives of this study were to investigate 1) the effects of Selenium(Se), Vitamin E (Vit. E) or recombinant Bovine Somatotropin(rBST) administration on fresh and frozen/thawed semen characteristics and 2) the effect of taurine on frozen/thawed semen characteristics in Hanwoo sires Hanwoo sires were randomly assigned to five groups (1. control, 2. rBST, 0.09mg/kg body weight (BW), 3. Vito E 1,500IU/kg BW, 4. Se 0.l mg/kg BW, 5. Vit. E 1,500IU plus Se 0.1 mg/kg BW). The administration of Se, Vit. E and rBST for each experimental group were given 6 times at 15 days interval by intramuscular injection. The administration of Se, Vit. E or rBST in Hanwoo sires didn't affect semen volume and pH values, but sperm viability was significantly increased comparing to the control group. Also, frozen/thawed semen analysis showed that the sperm viability increased, but any other effects were not found in total sperm :lumber, motility and abnormality among treatments. The addition of taurine in semen freezing extender had a beneficial effects on frozen/thawecl semen characteristics in all groups. The administrations of rBST, Vit. E and Se did not affect the sperm capacitation and acrosome reaction, either the ratio of F pattern(uncapacitated and acrosome intact sperm) or AR pattern(capacitated and acrosome-reacted sperm), but the ratio of B patten(capacitated and acrosome intact sperm) of treatment groups was significantly higher than that of control group, These results indicated that the viability, motility and quality of semen in Hanwoo sires were slightly increased by the injection of rBST, Vit. E and Se, and the addition of taurine in semen freezing extender were also increased the semen characteristics after thawing.

• Fire Science and Engineering
• /
• v.28 no.5
• /
• pp.8-13
• /
• 2014

The purpose of this study is to analyze the damage pattern when overcurrent is applied to a thermal magnetic type molded case circuit breaker (MCCB) using a Primary Current Injection Test System (PCITS). When an overcurrent of 150 A was applied to the PCITS for 5 seconds with the trip bar of an MCCB being damaged, it was found that the surface of the temperature control device (bimetallic strip) positioned at the right was significantly carbonized. When an overcurrent of 300 A was applied to the PCITS for 5 s under the same conditions, the entire temperature control device was deteriorated, becoming flattened and in close contact with the MCCB. When an overcurrent of 450 A was applied to the PCITS for 5 s, the coil of the temperature control device was melted and disconnected. In addition, it was observed that the contacts, the enclosure and upper cover were deformed and there was a trace of carbonization on them. When approximately 3 s had elapsed after an overcurrent of 600 A was applied, white smoke occurred inside the MCCB and a flame was radiated out, after which the overcurrent supply stopped with "phutt" (whomp) sound. It was observed that when the same type of MCCB is damaged by a general flame, the surfaces of its handle, terminal, arc divider (extinguisher) and temperature control device were carbonized uniformly. In addition, it was found that the trip bar of the operating mechanism was melted down and the metal operation pin was moved while being tripped.

• Clean Technology
• /
• v.28 no.3
• /
• pp.227-231
• /
• 2022

The demand for high-voltage power devices is rising in various industries, but especially in the transportation industry due to autonomous driving and electric vehicles. IGBT module parts of 3.3 kV or more are used in the power propulsion control device of electric vehicles, and the procurement of these parts for new construction and maintenance is increasing every year. In addition, research to optimize high-voltage IGBT parts is urgently required to overcome their very high technology entry barrier. For the development of high-voltage IGBT devices over 3.3 kV, the resistivity range setting of the wafer and the optimal conditions for major unit processes are important variables. Among the manufacturing processes to secure the optimal junction depth, the optimization of the diffusion process, which is one step of the unit process, was examined. In the diffusion process, the type of gas injected, the injection time, and the injection temperature are the main variables. In this study, the range of wafer resistance (Ω cm) was set for the development of high voltage IGBT devices through unit process simulation. Additionally, the well drive in (WDR) condition optimization of the diffusion process according to temperature was studied. The junction depth was 7.4 to7.5 ㎛ for a ring pattern width of 23.5 to25.87 ㎛, which can be optimized for supporting 3.3 kV high voltage power devices.

• International Journal of Aeronautical and Space Sciences
• /
• v.15 no.4
• /
• pp.444-453
• /
• 2014

A throttleable rocket engine enables operational possibilities such as the docking of spacecraft, maneuvering in a certain orbit and landing on a planet's surface, altitude control, and entrance to atmosphere-less planets. Thus, throttling methods have long been researched. However, dual-manifold injectors, which represent one throttling method, have been investigated less than others. In this study, dual-manifold and single-manifold injectors were compared to determine the characteristics of dual-manifold injectors. Also, the effects of gas injection were investigated with various F/O ratios. To investigate the characteristics, mass flow rate, spray pattern, spray angle, and droplet size were measured. The spray angle and droplet size were captured by indirect photography. About 30 images were taken to assess the spray patterns and spray angle. Also, 700 images were analyzed to understand the droplet distribution and targeting area, moving to the right from the centerline with 1.11-cm intervals. The droplet size was obtained from an image processing procedure. From the results, the spray angle showed two transition regions, due to swirl momentum in the swirl chamber regardless of the F/O ratio. The droplet size showed similar trends in both dual-manifold and single-manifold injectors except in the low mass flow rate region. In the case of the dual- manifold injector, the spray cone was not fully developed in the low mass flow rate region due to low angular momentum in the swirl chamber.